Survey of metal tolerance in moderately halophilic eubacteria.

PubMed

Nieto, J J; Fernández-Castillo, R; Márquez, M C; Ventosa, A; Quesada, E; Ruiz-Berraquero, F

1989-09-01

The tolerance patterns, expressed as MICs, for 250 moderately halophilic eubacteria to 10 heavy metals were surveyed by using an agar dilution method. The moderate halophiles tested included 12 culture collection strains and fresh isolates representative of Deleya halophila (37 strains), Acinetobacter sp. (24 strains), Flavobacterium sp. (28 strains), and 149 moderately halophilic gram-positive cocci included in the genera Marinococcus, Sporosarcina, Micrococcus, and Staphylococcus. On the basis of the MICs, the collection strains showed, overall, similar responses to silver, cobalt, mercury, nickel, lead, and zinc. All were sensitive to silver, mercury, and zinc and tolerant of lead. The response to arsenate, cadmium, chromium, and copper was very heterogeneous. The metal susceptibility levels of the 238 freshly isolated strains were, in general, very heterogeneous among the four taxonomic groups as well as within the strains included in each group. The highest toxicities were found with mercury, silver, and zinc, while arsenate showed the lowest activity. All these strains were tolerant of nickel, lead, and chromium and sensitive to silver and mercury. Acinetobacter sp. strains were the most heavy-metal tolerant, with the majority of them showing tolerance of eight different metal ions. In contrast, Flavobacterium sp. strains were the most metal sensitive. The influence of salinity and yeast extract concentrations of the culture medium on the toxicity of the heavy metals tested for some representative strains was also studied. Lowering the salinity, in general, led to enhanced sensitivity to cadmium and, in some cases, to cobalt and copper. However, increasing the salinity resulted in only a slight decrease in the cadmium, copper, and nickel toxicities.(ABSTRACT TRUNCATED AT 250 WORDS)

Genomic Characterization of Methanomicrobiales Reveals Three Classes of Methanogens

DOE Office of Scientific and Technical Information (OSTI.GOV)

Anderson, Iain; Ulrich, Luke; Lupa, Boguslaw

2009-01-01

Background Methanomicrobiales is the least studied order of methanogens. While these organisms appear to be more closely related to the Methanosarcinales in ribosomal-based phylogenetic analyses, they are metabolically more similar to Class I methanogens. Methodology/Principal Findings In order to improve our understanding of this lineage, we have completely sequenced the genomes of two members of this order, Methanocorpusculum labreanum Z and Methanoculleus marisnigri JR1, and compared them with the genome of a third, Methanospirillum hungatei JF-1. Similar to Class I methanogens, Methanomicrobiales use a partial reductive citric acid cycle for 2-oxoglutarate biosynthesis, and they have the Eha energy-converting hydrogenase. Inmore » common with Methanosarcinales, Methanomicrobiales possess the Ech hydrogenase and at least some of them may couple formylmethanofuran formation and heterodisulfide reduction to transmembrane ion gradients. Uniquely, M. labreanum and M. hungatei contain hydrogenases similar to the Pyrococcus furiosus Mbh hydrogenase, and all three Methanomicrobiales have anti-sigma factor and anti-anti-sigma factor regulatory proteins not found in other methanogens. Phylogenetic analysis based on seven core proteins of methanogenesis and cofactor biosynthesis places the Methanomicrobiales equidistant from Class I methanogens and Methanosarcinales. Conclusions/Significance Our results indicate that Methanomicrobiales, rather than being similar to Class I methanogens or Methanomicrobiales, share some features of both and have some unique properties. We find that there are three distinct classes of methanogens: the Class I methanogens, the Methanomicrobiales (Class II), and the Methanosarcinales (Class III).« less

Genomic Characterization of Methanomicrobiales Reveals Three Classes of Methanogens

DOE Office of Scientific and Technical Information (OSTI.GOV)

Anderson, Iain; Ulrich, Luke E.; Lupa, Boguslaw

2009-05-01

Methanomicrobiales is the least studied order of methanogens. While these organisms appear to be more closely related to the Methanosarcinales in ribosomal-based phylogenetic analyses, they are metabolically more similar to Class I methanogens. In order to improve our understanding of this lineage, we have completely sequenced the genomes of two members of this order, Methanocorpusculum labreanum Z and Methanoculleus marisnigri JR1, and compared them with the genome of a third, Methanospirillum hungatei JF-1. Similar to Class I methanogens, Methanomicrobiales use a partial reductive citric acid cycle for 2-oxoglutarate biosynthesis, and they have the Eha energy-converting hydrogenase. In common with Methanosarcinales,more » Methanomicrobiales possess the Ech hydrogenase and at least some of them may couple formylmethanofuran formation and heterodisulfide reduction to transmembrane ion gradients. Uniquely, M. labreanum and M. hungatei contain hydrogenases similar to the Pyrococcus furiosus Mbh hydrogenase, and all three Methanomicrobiales have anti-sigma factor and anti-anti-sigma factor regulatory proteins not found in other methanogens. Phylogenetic analysis based on seven core proteins of methanogenesis and cofactor biosynthesis places the Methanomicrobiales equidistant from Class I methanogens and Methanosarcinales. Our results indicate that Methanomicrobiales, rather than being similar to Class I methanogens or Methanomicrobiales, share some features of both and have some unique properties. We find that there are three distinct classes of methanogens: the Class I methanogens, the Methanomicrobiales (Class II), and the Methanosarcinales (Class III).« less

Impact of fulvic acids on bio-methanogenic treatment of municipal solid waste incineration leachate.

PubMed

Dang, Yan; Lei, Yuqing; Liu, Zhao; Xue, Yiting; Sun, Dezhi; Wang, Li-Ying; Holmes, Dawn E

2016-12-01

A considerable amount of leachate with high fulvic acid (FA) content is generated during the municipal solid waste (MSW) incineration process. This incineration leachate is usually processed by downstream bio-methanogenic treatment. However, few studies have examined the impact that these compounds have on methanogenesis and how they are degraded and transformed during the treatment process. In this study, a laboratory-scale expanded granular sludge bed (EGSB) reactor was operated with MSW incineration leachate containing various concentrations of FA (1500 mg/L to 8000 mg/L) provided as the influent. We found that FA degradation rates decreased from 86% to 72% when FA concentrations in the reactor were increased, and that molecular size, level of humification and aromatization of the residual FA macromolecules all increased after bio-methanogenic treatment. Increasing FA influent concentrations also inhibited growth of hydrogenotrophic methanogens from the genus Methanobacterium and syntrophic bacteria from the genus Syntrophomonas, which resulted in a decrease in methane production and a concomitant increase in CO 2 content in the biogas. Sequences most similar to species from the genus Anaerolinea went up as FA concentrations increased. Bacteria from this genus are capable of extracellular electron transfer and may be using FA as an electron acceptor for growth or as a shuttle for syntrophic exchange with other microorganisms in the reactor. In order to determine whether FA could serve as an electron shuttle to promote syntrophy in an anaerobic digester, co-cultures of Geobacter metallireducens and G. sulfurreducens were grown in the presence of FA from raw leachate or from residual bioreactor effluent. While raw FA stimulated electron transfer between these two bacteria, residual FA did not have any electron shuttling abilities, indicating that FA underwent a significant transformation during the bio-methanogenic treatment process. These results are

Hydrocarbon activation under sulfate-reducing and methanogenic conditions proceeds by different mechanisms.

NASA Astrophysics Data System (ADS)

Head, Ian; Gray, Neil; Aitken, Caroline; Sherry, Angela; Jones, Martin; Larter, Stephen

2010-05-01

Microbial degradation of alkanes typically involves their conversion to fatty acids which are then catabolised by beta-oxidation. The critical step in this process is activation of the hydrocarbon. Under oxic conditions this is catalyzed by monooxygenase enzymes with the formation of long chain alcohols. In the absence of oxygen alternative alkane activation mechanisms have been observed or proposed. Fumarate addition to alkanes to form alkyl succinates is considered a central process in anaerobic hydrocarbon degradation. Comparative studies of crude oil degradation under sulphate-reducing and methanogenic conditions revealed distinctive patterns of compound class removal and metabolite formation. Alkyl succinates derived from C7 to C26 n-alkanes and branched chain alkanes were found in abundance in sulfate-reducing systems but these were not detected during methanogenic crude oil degradation. Only one other mechanism of alkane activation has been elucidated to date. This involves addition of carbon derived from bicarbonate/CO2 to C-3 of an alkane chain to form a 2-ethylalkane with subsequent removal of the ethyl group leading to the formation of a fatty acid 1 carbon shorter than the original alkane. 2-ethylalkanes have never been detected as metabolites of anaerobic alkane degradation and were not detected in crude oil-degrading methanogenic systems. Due to the range of alkanes present in crude oil it was not possible to infer the generation of C-odd acids from C-even alkanes which is characteristic of the C-3 carboxylation mechanism. Furthermore genes homologous to alkysuccinate synthetases were not detected in the methanogenic hydrocarbon degrading community by pyrosequencing of total DNA extracted from methanogenic enrichments cultures. beta-oxidation genes were detected and intriguingly, alcohol and aldehyde dehydrogenase genes were present. This offers the possibility that alkane activation in the methanogenic system does not proceed via acid metabolites

Molecular Signatures of Methanogens in Cultures and Environmental Samples

NASA Astrophysics Data System (ADS)

Summons, R. E.; Embaye, T.; Jahnke, L. L.; Baumgartner, M.

2002-12-01

The core lipids of methanogens comprise C20 and C40 isoprenoid chains, linked through ether bonds to glycerol. Additional structural diversity is encoded into the polar head groups that are attached to the glycerol ether cores. These compounds are potentially very useful as taxonomic markers in microbial mats and other environmental samples while the nature of the hydrocarbon chains provide a means to identify methanogenic inputs to ancient sediments. The structural diversity of methanogen polar lipids is most valuable when it can be directly correlated to 16S rRNA phylogeny. On the other hand, this diversity can also leads to analytical challenges because there is no single approach that works for all structural types. While some intact methanogen lipids have been identified using mass spectrometry and NMR spectroscopy, the most common means of analysing the lipid cores involves cleavage of the ether bonds using HI and subsequent reduction of the alkyl iodides to hydrocarbons with LiAlH4. One class of methanogenic lipids, the 3?-hydroxyarchaeols, escaped detection for some years because strong acid treatments in the analysis protocols destroyed hydroxyl-containing isoprenoid chains. We have been systematically re-examining the lipids of methanogens, using milder procedures involving weak acid hydrolysis of polar head groups, derivatisation to form trimethylsilyl ethers and analysis by GC-MS. As well as archaeol, sn-2- and sn-3-hydroxyarchaeol, we have tentatively identified a dihydroxyarchaeol in several Methanococcus sp. For Methanococcus thermolithotrophicus an analysis of the total lipid extracts using BBr3 as an ether cleavage reagent followed by LiBEt3H, reduction revealed a very complex mixture consisting of phytane, phytenes, biphytane, biphytenes and a suite of related alcohols. The latter compounds were analysed by GC-MS as their trimethylsilyl ethers and found to comprise a mixture tentatively identified as phytan-N-ol and biphytan-N-ol where N= 3 or 7

Evidence of Archaeal Methanogens in Brain Abscess.

PubMed

Drancourt, Michel; Nkamga, Vanessa Demonfort; Lakhe, Ndèye Aïssatou; Régis, Jean-Marie; Dufour, Henry; Fournier, Pierre-Edouard; Bechah, Yassina; Scheld, W Michael; Raoult, Didier

2017-07-01

Methanogens are antibiotic-resistant anaerobic archaea that escape routine detection in clinical microbiology. We hypothesized that methanogens are part of the anaerobic community that cause brain abscess. Methanogens were investigated in 1 index sample using specific polymerase chain reaction (PCR) sequencing and culture. The pathogenesis of a methanogen isolate was assessed in a mouse model. Archaea-specific quantitative (q) PCR and metagenomics were used to detect specific archaeal sequences in brain abscess samples and controls. In 1 index sample, routine culture found Porphyromonas endodontalis and Streptococcus intermedius, and specific culture found Methanobrevibacter oralis susceptible to metronidazole and fusidic acid. Archaea-targeted PCR sequencing and metagenomics confirmed M. oralis along with 14 bacteria, including S. intermedius. Archaea-specific qPCR yielded archaea in 8/18 brain abscess specimens and 1/27 controls (P < .003), and metagenomics yielded archaea, mostly methanogens, in 28/32 brain abscess samples, and no archaea in 71 negative controls (P < 10-6). Infection of mice brains yielded no mortality in 14 controls and death in 17/22 M. oralis-inoculated mice (P < 10-6), 32/95 S. intermedius-inoculated mice (P < 10-6), and 75/104 mice inoculated with M. oralis mixed with S. intermedius (P < 10-6) 7 days post-inoculation. Methanogens belong to the anaerobic community responsible for brain abscess, and M. oralis may participate in the pathogenicity of this deadly infection. In mice, a synergy of M. oralis and S. intermedius was observed. Antibiotic treatment of brain abscess should contain anti-archaeal compounds such as imidazole derivatives in most cases. © The Author 2017. Published by Oxford University Press for the Infectious Diseases Society of America. All rights reserved. For permissions, e-mail: journals.permissions@oup.com.

Efficacy and tolerability of a topical gel containing 3% hydrogen peroxide, 1.5% salicylic acid and 4% D-panthenol in the treatment of mild-moderate acne.

PubMed

Fabbrocini, Gabriella; Panariello, Luigia

2016-06-01

The aim of this paper was to evaluate efficacy and tolerability of a topical gel (ACNAID TM gel medical device) containing 3% hydrogen peroxide (HPO), 1.5% salicylic acid (SA) and 4% D-panthenol (D-p) in the treatment of mild-moderate acne, comparing it with a previous formulation (ACNAID TM gel Cosmetic) containing 4% HPO, 0.5% SA, 4% D-p. Twenty patients of both sex with mild-moderate acne have been selected. The topical gel was applied twice a day for 60 days. Evaluations included: Global Acne Grading System (GAGS); lesions count; photographic assessment; a questionnaire to assess the tolerability. The results have been compared with those obtained in a previous study conducted with the formulation containing 4% HPO, 0.5% SA, 4% D-p. The GAGS score showed a reduction of 43% from T0 to T1 and of 61% from T0 to T2. Count of lesions: comedones reduction of 62% from T0 to T1 and of 95% from T0 to T2; papules reduction of 49% from T0 to T1 and of 68% from T0 to T2; pustules reduction of 75% from T0 to T1 and of 100% from T0 to T2. Digital images showed a significant reduction of acne lesions. At T2 the tolerability of the topical product was excellent according to 83% of patients and good according to 17% of patients. The topical gel has demonstrated to be effective and safe for treatment of mild to moderate acne. No patients reported side effects. These results are superior to those obtained in the previous study.

Climate Clever Clovers: New Paradigm to Reduce the Environmental Footprint of Ruminants by Breeding Low Methanogenic Forages Utilizing Haplotype Variation

PubMed Central

Kaur, Parwinder; Appels, Rudi; Bayer, Philipp E.; Keeble-Gagnere, Gabriel; Wang, Jiankang; Hirakawa, Hideki; Shirasawa, Kenta; Vercoe, Philip; Stefanova, Katia; Durmic, Zoey; Nichols, Phillip; Revell, Clinton; Isobe, Sachiko N.; Edwards, David; Erskine, William

2017-01-01

Mitigating methane production by ruminants is a significant challenge to global livestock production. This research offers a new paradigm to reduce methane emissions from ruminants by breeding climate-clever clovers. We demonstrate wide genetic diversity for the trait methanogenic potential in Australia’s key pasture legume, subterranean clover (Trifolium subterraneum L.). In a bi-parental population the broadsense heritability in methanogenic potential was moderate (H2 = 0.4) and allelic variation in a region of Chr 8 accounted for 7.8% of phenotypic variation. In a genome-wide association study we identified four loci controlling methanogenic potential assessed by an in vitro fermentation system. Significantly, the discovery of a single nucleotide polymorphism (SNP) on Chr 5 in a defined haplotype block with an upstream putative candidate gene from a plant peroxidase-like superfamily (TSub_g18548) and a downstream lectin receptor protein kinase (TSub_g18549) provides valuable candidates for an assay for this complex trait. In this way haplotype variation can be tracked to breed pastures with reduced methanogenic potential. Of the quantitative trait loci candidates, the DNA-damage-repair/toleration DRT100-like protein (TSub_g26967), linked to avoid the severity of DNA damage induced by secondary metabolites, is considered central to enteric methane production, as are disease resistance (TSub_g26971, TSub_g26972, and TSub_g18549) and ribonuclease proteins (TSub_g26974, TSub_g26975). These proteins are good pointers to elucidate the genetic basis of in vitro microbial fermentability and enteric methanogenic potential in subterranean clover. The genes identified allow the design of a suite of markers for marker-assisted selection to reduce rumen methane emission in selected pasture legumes. We demonstrate the feasibility of a plant breeding approach without compromising animal productivity to mitigate enteric methane emissions, which is one of the most significant

Methanogens at the top of the world: occurrence and potential activity of methanogens in newly deglaciated soils in high-altitude cold deserts in the Western Himalayas

PubMed Central

Aschenbach, Katrin; Conrad, Ralf; Řeháková, Klára; Doležal, Jiří; Janatková, Kateřina; Angel, Roey

2013-01-01

Methanogens typically occur in reduced anoxic environments. However, in recent studies it has been shown that many aerated upland soils, including desert soils also host active methanogens. Here we show that soil samples from high-altitude cold deserts in the western Himalayas (Ladakh, India) produce CH4 after incubation as slurry under anoxic conditions at rates comparable to those of hot desert soils. Samples of matured soil from three different vegetation belts (arid, steppe, and subnival) were compared with younger soils originating from frontal and lateral moraines of receding glaciers. While methanogenic rates were higher in the samples from matured soils, CH4 was also produced in the samples from the recently deglaciated moraines. In both young and matured soils, those covered by a biological soil crust (biocrust) were more active than their bare counterparts. Isotopic analysis showed that in both cases CH4 was initially produced from H2/CO2 but later mostly from acetate. Analysis of the archaeal community in the in situ soil samples revealed a clear dominance of sequences related to Thaumarchaeota, while the methanogenic community comprised only a minor fraction of the archaeal community. Similar to other aerated soils, the methanogenic community was comprised almost solely of the genera Methanosarcina and Methanocella, and possibly also Methanobacterium in some cases. Nevertheless, ~103 gdw−1 soil methanogens were already present in the young moraine soil together with cyanobacteria. Our results demonstrate that Methanosarcina and Methanocella not only tolerate atmospheric oxygen but are also able to survive in these harsh cold environments. Their occurrence in newly deglaciated soils shows that they are early colonizers of desert soils, similar to cyanobacteria, and may play a role in the development of desert biocrusts. PMID:24348469

Organic acid-tolerant microorganisms and uses thereof for producing organic acids

DOEpatents

Pfleger, Brian Frederick; Begemann, Matthew Brett

2014-05-06

Organic acid-tolerant microorganisms and methods of using same. The organic acid-tolerant microorganisms comprise modifications that reduce or ablate AcsA activity or AcsA homolog activity. The modifications increase tolerance of the microorganisms to such organic acids as 3-hydroxypropionic acid (3HP), acrylic acid, and propionic acid. Further modifications to the microorganisms such as increasing expression of malonyl-CoA reductase and/or acetyl-CoA carboxylase provide or increase the ability of the microorganisms to produce 3HP. Methods of generating an organic acid with the modified microorganisms are provided. Methods of using acsA or homologs thereof as counter-selectable markers include replacing acsA or homologs thereof in cells with genes of interest and selecting for the cells comprising the genes of interest with amounts of organic acids effective to inhibit growth of cells harboring acsA or the homologs.

Genetic dissection of acetic acid tolerance in Saccharomyces cerevisiae.

PubMed

Geng, Peng; Xiao, Yin; Hu, Yun; Sun, Haiye; Xue, Wei; Zhang, Liang; Shi, Gui-Yang

2016-09-01

Dissection of the hereditary architecture underlying Saccharomyces cerevisiae tolerance to acetic acid is essential for ethanol fermentation. In this work, a genomics approach was used to dissect hereditary variations in acetic acid tolerance between two phenotypically different strains. A total of 160 segregants derived from these two strains were obtained. Phenotypic analysis indicated that the acetic acid tolerance displayed a normal distribution in these segregants, and suggested that the acetic acid tolerant traits were controlled by multiple quantitative trait loci (QTLs). Thus, 220 SSR markers covering the whole genome were used to detect QTLs of acetic acid tolerant traits. As a result, three QTLs were located on chromosomes 9, 12, and 16, respectively, which explained 38.8-65.9 % of the range of phenotypic variation. Furthermore, twelve genes of the candidates fell into the three QTL regions by integrating the QTL analysis with candidates of acetic acid tolerant genes. These results provided a novel avenue to obtain more robust strains.

Effect of humic acid in leachate on specific methanogenic activity of anaerobic granular sludge.

PubMed

Guo, Mengfei; Xian, Ping; Yang, Longhui; Liu, Xi; Zhan, Longhui; Bu, Guanghui

2015-01-01

In order to find out the effects of humic acid (HA) in anaerobic-treated landfill leachate on granular sludge, the anaerobic biodegradability of HA as well as the influences of HA on the total cumulative methane production, the anaerobic methanization process and the specific methanogenic activity (SMA) of granular sludge are studied in this paper. Experimental results show that as a non-biodegradable organic pollutant, HA is also difficult to be decomposed by microbes in the anaerobic reaction process. Presence of HA and changes in the concentration have no significant influences on the total cumulative methane production and the anaerobic methanization process of granular sludge. Besides, the total cumulative methane production cannot reflect the inhibition of toxics on the methanogenic activity of granular sludge on the premise of sufficient reaction time. Results also show that HA plays a promoting role on SMA of granular sludge. Without buffering agent the SMA value increased by 19.2% on average due to the buffering and regulating ability of HA, while with buffering agent the SMA value increased by 5.4% on average due to the retaining effect of HA on the morphology of the sludge particles. However, in the presence of leachate the SMA value decreased by 27.6% on average, because the toxic effect of the toxics in the leachate on granular sludge is much larger than the promoting effect of HA.

Bioactive fractions from the pasture legume Biserrula pelecinus L. have an anti-methanogenic effect against key rumen methanogens.

PubMed

Banik, Bidhyut K; Durmic, Zoey; Erskine, William; Revell, Clinton K; Vadhanabhuti, Joy; McSweeney, Christopher S; Padmanabha, Jagadish; Flematti, Gavin R; Algreiby, Azizah A; Vercoe, Philip E

2016-06-01

Methanogenic archaea (methanogens) are common inhabitants of the mammalian intestinal tract. In ruminants, they are responsible for producing abundant amounts of methane during digestion of food, but selected bioactive plants and compounds may inhibit this activity. Recently, we have identified that, Biserrula pelecinus L. (biserrula) is one such plant and the current study investigated the specific anti-methanogenic activity of the plant. Bioassay-guided extraction and fractionation, coupled with in vitro fermentation batch culture were used to select the most bioactive fractions of biserrula. The four fractions were then tested against five species of methanogens grown in pure culture. Fraction bioactivity was assessed by measuring methane production and amplification of the methanogen mcrA gene. Treatments that showed bioactivity were subcultured in fresh broth without the bioactive fraction to distinguish between static and cidal effects. All four fractions were active against pure cultures, but the F2 fraction was the most consistent inhibitor of both methane production and cell growth, affecting four species of methanogens and also producing equivocal-cidal effects on the methanogens. Other fractions had selective activity affecting only some methanogens, or reducing either methane production or methanogenic cell growth. In conclusion, the anti-methanogenic activity of biserrula can be linked to compounds contained in selected bioactive fractions, with the F2 fraction strongly affecting key rumen methanogens. Further study is required to identify the specific plant compounds in biserrula that are responsible for the anti-methanogenic activity. These findings will help devise novel strategies to control methanogen populations and activity in the rumen, and consequently contribute in reducing greenhouse gas emissions from ruminants. Crown Copyright © 2016. Published by Elsevier Ltd. All rights reserved.

Quantitative analysis of rate and extent of tolerance of biomarkers: application to nicotinic acid-induced changes in non-esterified fatty acids in rats.

PubMed

Ahlström, Christine; Peletier, Lambertus A; Gabrielsson, Johan

2011-10-09

In this paper we quantitatively evaluate two feedback systems with a focus on rate and extent of tolerance and rebound development. In the two feedback systems, the regulation of turnover of response is governed by one or several moderators. In the basic system, one single moderator inhibits the formation of response. This system has been applied to cortisol secretion and serotonin reuptake inhibition. The basic system has been extended to adequately describe nicotinic acid (NiAc)-induced changes in non-esterified fatty acids (NEFA). In the extended system, the feedback is described by a cascade of moderators where the first inhibits formation of response and the last stimulates loss of response. The objectives of this paper were to analyze these systems from a mathematical/analytical and quantitative point of view and to present simulations with different parameter settings and dosing regimens in order to highlight the intrinsic behaviour of these systems and to present expressions and graphs that are applicable for quantification of rate and extent of tolerance and rebound. The dynamics of the moderators (k(tol)) compared to the dynamics of the response (k(out)), was shown to be important for the behaviour of both systems. For instance, slow dynamics of the moderator compared to the response (k(tol)tolerance was studied over time at a single constant drug concentration and at steady state for different drug concentrations and was found to be largest at drug concentrations close to IC(50). An upper limit for the response could be identified and included in the quantification of extent of rebound. Especially, for the extended system, the duration of exposure was an important factor affecting size of rebound. The rate of tolerance development was addressed by quantitatively estimating the time to steady state for the two systems, in which the value of k(tol) and the length of the cascade were

40 CFR 180.202 - p-Chlorophenoxyacetic acid; tolerances for residues.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 24 2014-07-01 2014-07-01 false p-Chlorophenoxyacetic acid; tolerances... Tolerances § 180.202 p-Chlorophenoxyacetic acid; tolerances for residues. (a) General. A tolerance is established for the combined residues of the plant regulator p-chlorophenoxyacetic acid and its metabolite p...

40 CFR 180.202 - p-Chlorophenoxyacetic acid; tolerances for residues.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 25 2013-07-01 2013-07-01 false p-Chlorophenoxyacetic acid; tolerances... Tolerances § 180.202 p-Chlorophenoxyacetic acid; tolerances for residues. (a) General. A tolerance is established for the combined residues of the plant regulator p-chlorophenoxyacetic acid and its metabolite p...

40 CFR 180.202 - p-Chlorophenoxyacetic acid; tolerances for residues.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 25 2012-07-01 2012-07-01 false p-Chlorophenoxyacetic acid; tolerances... Tolerances § 180.202 p-Chlorophenoxyacetic acid; tolerances for residues. (a) General. A tolerance is established for the combined residues of the plant regulator p-chlorophenoxyacetic acid and its metabolite p...

Dynamics of two methanogenic microbiomes incubated in polycyclic aromatic hydrocarbons, naphthenic acids, and oil field produced water.

PubMed

Oko, Bonahis J; Tao, Yu; Stuckey, David C

2017-01-01

Oil field produced water (OFPW) is widely produced in large volumes around the world. Transforming the organic matter in OFPW into bioenergy, such as biomethane, is one promising way to sustainability. However, OFPW is difficult to biologically degrade because it contains complex compounds such as naphthenic acids (NAs), or polycyclic aromatic hydrocarbons (PAHs). Although active microbial communities have been found in many oil reservoirs, little is known about how an exotic microbiome, e.g. the one which originates from municipal wastewater treatment plants, would evolve when incubated with OFPW. In this study, we harvested methanogenic biomass from two sources: a full-scale anaerobic digester (AD) treating oil and gas processing wastewater (named O&G sludge), and from a full-scale AD reactor treating multiple fractions of municipal solid wastes (named MS, short for mixed sludge). Both were incubated in replicate microcosms fed with PAHs, NAs, or OFPW. The results showed that the PAHs, NAs, and OFPW feeds could rapidly alter the methanogenic microbiomes, even after 14 days, while the O&G sludge adapted faster than the mixed sludge in all the incubations. Two rarely reported microorganisms, a hydrogenotrophic methanogen Candidatus methanoregula and a saccharolytic fermenter Kosmotoga , were found to be prevalent in the PAHs and OFPW microcosms, and are likely to play an important role in the syntrophic degradation of PAHs and OFPW, cooperating with methanogens such as Methanoregula, Methanosarcina, or Methanobacterium . The dominant phyla varied in certain patterns during the incubations, depending on the biomass source, feed type, and variation in nutrients. The sludge that originated from the oil and gas processing wastewater treatment (O&G) reactor adapted faster than the one from municipal solid waste reactors, almost certainly because the O&G biomass had been "pre-selected" by the environment. This study reveals the importance of biomass selection for other

Carbon and hydrogen isotope fractionation by moderately thermophilic methanogens

NASA Astrophysics Data System (ADS)

Valentine, David L.; Chidthaisong, Amnat; Rice, Andrew; Reeburgh, William S.; Tyler, Stanley C.

2004-04-01

A series of laboratory studies were conducted to increase understanding of stable carbon (13C/12C) and hydrogen (D/H) isotope fractionation arising from methanogenesis by moderately thermophilic acetate- and hydrogen-consuming methanogens. Studies of the aceticlastic reaction were conducted with two closely related strains of Methanosaeta thermophila. Results demonstrate a carbon isotope fractionation of only 7‰ (α = 1.007) between the methyl position of acetate and the resulting methane. Methane formed by this process is enriched in 13C when compared with other natural sources of methane; the magnitude of this isotope effect raises the possibility that methane produced at elevated temperature by the aceticlastic reaction could be mistaken for thermogenic methane based on carbon isotopic content. Studies of H2/CO2 methanogenesis were conducted with Methanothermobacter marburgensis. The fractionation of carbon isotopes between CO2 and CH4 was found to range from 22 to 58‰ (1.023 ≤ α ≤ 1.064). Greater fractionation was associated with low levels of molecular hydrogen and steady-state metabolism. The fractionation of hydrogen isotopes between source H2O and CH4 was found to range from 127 to 275‰ (1.16 ≤ α ≤ 1.43). Fractionation was dependent on growth phase with greater fractionation associated with later growth stages. The maximum observed fractionation factor was 1.43, independent of the δD-H2 supplied to the culture. Fractionation was positively correlated with temperature and/or metabolic rate. Results demonstrate significant variability in both hydrogen and carbon isotope fractionation during methanogenesis from H2/CO2. The relatively small fractionation associated with deuterium during H2/CO2 methanogenesis provides an explanation for the relatively enriched deuterium content of biogenic natural gas originating from a variety of thermal environments. Results from these experiments are used to develop a hypothesis that differential

Methanohalophilus zhilinae sp. nov., an alkaliphilic, halophilic, methylotrophic methanogen

NASA Technical Reports Server (NTRS)

Mathrani, I. M.; Boone, D. R.; Mah, R. A.; Fox, G. E.; Lau, P. P.

1988-01-01

Methanohalophilus zhilinae, a new alkaliphilic, halophilic, methylotrophic species of methanogenic bacteria, is described. Strain WeN5T (T = type strain) from Bosa Lake of the Wadi el Natrun in Egypt was designated the type strain and was further characterized. This strain was nonmotile, able to catabolize dimethylsulfide, and able to grow in medium with a methyl group-containing substrate (such as methanol or trimethylamine) as the sole organic compound added. Sulfide (21 mM) inhibited cultures growing on trimethylamine. The antibiotic susceptibility pattern of strain WeN5T was typical of the pattern for archaeobacteria, and the guanine-plus-cytosine content of the deoxyribonucleic acid was 38 mol%. Characterization of the 16S ribosomal ribonucleic acid sequence indicated that strain WeN5T is phylogenetically distinct from members of previously described genera other than Methanohalophilus and supported the partition of halophilic methanogens into their own genus.

[Effects of selective methanogenic inhibitors on methanogenesis and methanogenic communities in acetate degrading cultures].

PubMed

Ma, Tingting; Cheng, Lei; Liu, Laiyan; Dai, Lirong; Zhou, Zheng; Zhang, Hui

2015-05-04

We evaluated the role of syntrophic acetate oxidation coupled with hydrogenotrophic methanogens in three different methanogenic consortia. Three methanogenic hexadecane degrading consortia named Y15, M82 and SK were taken from the same oily sludge of Shengli oil-field and enriched. They were incubated at 15, 35 and 55 °C, respectively. The consortia amended with acetate and inhibitors of NH4Cl or CH3F were further transferred and incubated at corresponding temperatures. The cultures atlate logarithmic phase were collected for terminal restriction fragment length polymorphism (T-RFLP) combined with cloning and phylogenetic analysis of 16S rRNA gene fragments. Gas chromatograph analysis showed that all of the consortia could grow and produce methane, but the lag phase was delayed and the growth rate was retarded in the cultures amended with inhibitor. Combination analysis of T-RFLP and clone library revealed the predominance of obligate aceticlastic Methanosaeta in the acetate cultures of Y15, M82 and SK. Under the mesophilic and thermophilic conditions, after add inginhibitor the relative abundance of aceticlastic methanogen decreased but hydrogenotrophic methanogen increased. Syntrophic acetate oxidation during methanogenic degradation of petroleum hydrocarbons occurs under mesophilic and thermophilic conditions, although the situation at low temperature seems uncertain.

Microbial dark matter ecogenomics reveals complex synergistic networks in a methanogenic bioreactor.

PubMed

Nobu, Masaru K; Narihiro, Takashi; Rinke, Christian; Kamagata, Yoichi; Tringe, Susannah G; Woyke, Tanja; Liu, Wen-Tso

2015-08-01

Ecogenomic investigation of a methanogenic bioreactor degrading terephthalate (TA) allowed elucidation of complex synergistic networks of uncultivated microorganisms, including those from candidate phyla with no cultivated representatives. Our previous metagenomic investigation proposed that Pelotomaculum and methanogens may interact with uncultivated organisms to degrade TA; however, many members of the community remained unaddressed because of past technological limitations. In further pursuit, this study employed state-of-the-art omics tools to generate draft genomes and transcriptomes for uncultivated organisms spanning 15 phyla and reports the first genomic insight into candidate phyla Atribacteria, Hydrogenedentes and Marinimicrobia in methanogenic environments. Metabolic reconstruction revealed that these organisms perform fermentative, syntrophic and acetogenic catabolism facilitated by energy conservation revolving around H2 metabolism. Several of these organisms could degrade TA catabolism by-products (acetate, butyrate and H2) and syntrophically support Pelotomaculum. Other taxa could scavenge anabolic products (protein and lipids) presumably derived from detrital biomass produced by the TA-degrading community. The protein scavengers expressed complementary metabolic pathways indicating syntrophic and fermentative step-wise protein degradation through amino acids, branched-chain fatty acids and propionate. Thus, the uncultivated organisms may interact to form an intricate syntrophy-supported food web with Pelotomaculum and methanogens to metabolize catabolic by-products and detritus, whereby facilitating holistic TA mineralization to CO2 and CH4.

Vitamin and Amino Acid Auxotrophy in Anaerobic Consortia Operating under Methanogenic Conditions

PubMed Central

Hubalek, Valerie; Buck, Moritz; Tan, BoonFei; Foght, Julia; Wendeberg, Annelie; Berry, David; Bertilsson, Stefan

2017-01-01

ABSTRACT Syntrophy among Archaea and Bacteria facilitates the anaerobic degradation of organic compounds to CH4 and CO2. Particularly during aliphatic and aromatic hydrocarbon mineralization, as in the case of crude oil reservoirs and petroleum-contaminated sediments, metabolic interactions between obligate mutualistic microbial partners are of central importance. Using micromanipulation combined with shotgun metagenomic approaches, we describe the genomes of complex consortia within short-chain alkane-degrading cultures operating under methanogenic conditions. Metabolic reconstruction revealed that only a small fraction of genes in the metagenome-assembled genomes encode the capacity for fermentation of alkanes facilitated by energy conservation linked to H2 metabolism. Instead, the presence of inferred lifestyles based on scavenging anabolic products and intermediate fermentation products derived from detrital biomass was a common feature. Additionally, inferred auxotrophy for vitamins and amino acids suggests that the hydrocarbon-degrading microbial assemblages are structured and maintained by multiple interactions beyond the canonical H2-producing and syntrophic alkane degrader-methanogen partnership. Compared to previous work, our report points to a higher order of complexity in microbial consortia engaged in anaerobic hydrocarbon transformation. IMPORTANCE Microbial interactions between Archaea and Bacteria mediate many important chemical transformations in the biosphere from degrading abundant polymers to synthesis of toxic compounds. Two of the most pressing issues in microbial interactions are how consortia are established and how we can modulate these microbial communities to express desirable functions. Here, we propose that public goods (i.e., metabolites of high energy demand in biosynthesis) facilitate energy conservation for life under energy-limited conditions and determine the assembly and function of the consortia. Our report suggests that an

Fast pyrolysis product distribution of biopretreated corn stalk by methanogen.

PubMed

Wang, Tipeng; Ye, Xiaoning; Yin, Jun; Jin, Zaixing; Lu, Qiang; Zheng, Zongming; Dong, Changqing

2014-10-01

After pretreated by methanogen for 5, 15 and 25 days, corn stalk (CS) were pyrolyzed at 250, 300, 350, 400, 450 and 500 °C by Py-GC/MS and product distribution in bio-oil was analyzed. Results indicated that methanogen pretreatment changed considerably the product distribution: the contents of sugar and phenols increased; the contents of linear carbonyls and furans decreased; the contents of linear ketones and linear acids changed slightly. Methanogen pretreatment improved significantly the pyrolysis selectivity of CS to phenols especially 4-VP. At 250 °C, the phenols content increased from 42.25% for untreated CS to 79.32% for biopretreated CS for 5 days; the 4-VP content increased from 28.6% to 60.9%. Increasing temperature was contributed to convert more lignin into 4-VP, but decreased its content in bio-oil due to more other chemicals formed. The effects of biopretreatment time on the chemicals contents were insignificant. Copyright © 2014 Elsevier Ltd. All rights reserved.

Effects of cattle husbandry on abundance and activity of methanogenic archaea in upland soils.

PubMed

Radl, Viviane; Gattinger, Andreas; Chronáková, Alica; Nemcová, Anna; Cuhel, Jiri; Simek, Miloslav; Munch, Jean Charles; Schloter, Michael; Elhottová, Dana

2007-09-01

In the present study, we tested the hypothesis that animal treading associated with a high input of organic matter would favour methanogenesis in soils used as overwintering pasture. Hence, methane emissions and methanogen populations were examined at sections with different degree of cattle impact in a Farm in South Bohemia, Czech Republic. In spring, methane emission positively corresponded to the gradient of animal impact. Applying phospholipid etherlipid analysis, the highest archaeal biomass was found in section severe impact (SI), followed by moderate impact (MI) and no impact. The same trend was observed for the methanogens as showed by real-time quantitative PCR analyses of methyl coenzyme M reductase (mcrA) genes. The detection of monounsaturated isoprenoid side chain hydrocarbons (i20:1) indicated the presence of acetoclastic methanogens in the cattle-impacted sites. This result was corroborated by the phylogenetic analysis of mcrA gene sequences obtained from section SI, which showed that 33% of the analysed clones belonged to the genus Methanosarcina. The majority of the sequenced clones (41%) showed close affiliations with uncultured rumen archaeons. This leads to the assumption that a substantial part of the methanogenic community in plot SI derived from the grazing cattle itself. Compared to the spring sampling, in autumn, a significant reduction in archaeal biomass and number of copies of mcrA genes was observed mainly for section MI. It can be concluded that after 5 months without cattle impact, the severely impact section maintained its methane production potential, whereas the methane production potential under moderate impact returned to background values.

Conductive properties of methanogenic biofilms.

PubMed

Li, Cheng; Lesnik, Keaton Larson; Liu, Hong

2018-02-01

Extracellular electron transfer between syntrophic partners needs to be efficiently maintained in methanogenic environments. Direct extracellular electron transfer via electrical current is an alternative to indirect hydrogen transfer but requires construction of conductive extracellular structures. Conductive mechanisms and relationship between conductivity and the community composition in mixed-species methanogenic biofilms are not well understood. The present study investigated conductive behaviors of methanogenic biofilms and examined the correlation between biofilm conductivity and community composition between different anaerobic biofilms enriched from the same inoculum. Highest conductivity observed in methanogenic biofilms was 71.8±4.0μS/cm. Peak-manner response of conductivity upon changes over a range of electrochemical potentials suggests that electron transfer in methanogenic biofilms occurs through redox driven super-exchange. The strong correlation observed between biofilm conductivity and Geobacter spp. in the metabolically diverse anaerobic communities suggests that the efficiency of DEET may provide pressure for microbial communities to select for species that can produce electrical conduits. Copyright © 2017 Elsevier B.V. All rights reserved.

Omics analysis of acetic acid tolerance in Saccharomyces cerevisiae.

PubMed

Geng, Peng; Zhang, Liang; Shi, Gui Yang

2017-05-01

Acetic acid is an inhibitor in industrial processes such as wine making and bioethanol production from cellulosic hydrolysate. It causes energy depletion, inhibition of metabolic enzyme activity, growth arrest and ethanol productivity losses in Saccharomyces cerevisiae. Therefore, understanding the mechanisms of the yeast responses to acetic acid stress is essential for improving acetic acid tolerance and ethanol production. Although 329 genes associated with acetic acid tolerance have been identified in the Saccharomyces genome and included in the database ( http://www.yeastgenome.org/observable/resistance_to_acetic_acid/overview ), the cellular mechanistic responses to acetic acid remain unclear in this organism. Post-genomic approaches such as transcriptomics, proteomics, metabolomics and chemogenomics are being applied to yeast and are providing insight into the mechanisms and interactions of genes, proteins and other components that together determine complex quantitative phenotypic traits such as acetic acid tolerance. This review focuses on these omics approaches in the response to acetic acid in S. cerevisiae. Additionally, several novel strains with improved acetic acid tolerance have been engineered by modifying key genes, and the application of these strains and recently acquired knowledge to industrial processes is also discussed.

β-Aminobutyric acid increases abscisic acid accumulation and desiccation tolerance and decreases water use but fails to improve grain yield in two spring wheat cultivars under soil drying.

PubMed

Du, Yan-Lei; Wang, Zhen-Yu; Fan, Jing-Wei; Turner, Neil C; Wang, Tao; Li, Feng-Min

2012-08-01

A pot experiment was conducted to investigate the effect of the non-protein amino acid, β-aminobutyric acid (BABA), on the homeostasis between reactive oxygen species (ROS) and antioxidant defence during progressive soil drying, and its relationship with the accumulation of abscisic acid (ABA), water use, grain yield, and desiccation tolerance in two spring wheat (Triticum aestivum L.) cultivars released in different decades and with different yields under drought. Drenching the soil with 100 µM BABA increased drought-induced ABA production, leading to a decrease in the lethal leaf water potential (Ψ) used to measure desiccation tolerance, decreased water use, and increased water use efficiency for grain (WUEG) under moderate water stress. In addition, at severe water stress levels, drenching the soil with BABA reduced ROS production, increased antioxidant enzyme activity, and reduced the oxidative damage to lipid membranes. The data suggest that the addition of BABA triggers ABA accumulation that acts as a non-hydraulic root signal, thereby closing stomata, and reducing water use at moderate stress levels, and also reduces the production of ROS and increases the antioxidant defence enzymes at severe stress levels, thus increasing the desiccation tolerance. However, BABA treatment had no effect on grain yield of wheat when water availability was limited. The results suggest that there are ways of effectively priming the pre-existing defence pathways, in addition to genetic means, to improve the desiccation tolerance and WUEG of wheat.

Acid and bile tolerance of spore-forming lactic acid bacteria.

PubMed

Hyronimus, B; Le Marrec, C; Sassi, A H; Deschamps, A

2000-11-01

Criteria for screening probiotics such as bile tolerance and resistance to acids were studied with 13 spore-forming lactic acid producing bacteria. Different strains of Sporolactobacillus, Bacillus laevolacticus, Bacillus racemilacticus and Bacillus coagulans grown in MRS broth were subjected to low pH conditions (2, 2.5 and 3) and increasing bile concentrations. Among these microorganisms, Bacillus laevolacticus DSM 6475 and all Sporolactobacillus strains tested except Sporolactobacillus racemicus IAM 12395, were resistant to pH 3. Only Bacillus racemilacticus and Bacillus coagulans strains were tolerant to bile concentrations over 0.3% (w/v).

Carbon nanotubes accelerate methane production in pure cultures of methanogens and in a syntrophic coculture.

PubMed

Salvador, Andreia F; Martins, Gilberto; Melle-Franco, Manuel; Serpa, Ricardo; Stams, Alfons J M; Cavaleiro, Ana J; Pereira, M Alcina; Alves, M Madalena

2017-07-01

Carbon materials have been reported to facilitate direct interspecies electron transfer (DIET) between bacteria and methanogens improving methane production in anaerobic processes. In this work, the effect of increasing concentrations of carbon nanotubes (CNT) on the activity of pure cultures of methanogens and on typical fatty acid-degrading syntrophic methanogenic coculture was evaluated. CNT affected methane production by methanogenic cultures, although acceleration was higher for hydrogenotrophic methanogens than for acetoclastic methanogens or syntrophic coculture. Interestingly, the initial methane production rate (IMPR) by Methanobacterium formicicum cultures increased 17 times with 5 g·L -1 CNT. Butyrate conversion to methane by Syntrophomonas wolfei and Methanospirillum hungatei was enhanced (∼1.5 times) in the presence of CNT (5 g·L -1 ), but indications of DIET were not obtained. Increasing CNT concentrations resulted in more negative redox potentials in the anaerobic microcosms. Remarkably, without a reducing agent but in the presence of CNT, the IMPR was higher than in incubations with reducing agent. No growth was observed without reducing agent and without CNT. This finding is important to re-frame discussions and re-interpret data on the role of conductive materials as mediators of DIET in anaerobic communities. It also opens new challenges to improve methane production in engineered methanogenic processes. © 2017 The Authors. Environmental Microbiology published by Society for Applied Microbiology and John Wiley & Sons Ltd.

75 FR 37738 - 1-Naphthaleneacetic Acid; Time-Limited Tolerance, Technical Correction

Federal Register 2010, 2011, 2012, 2013, 2014

2010-06-30

...-Naphthaleneacetic Acid; Time-Limited Tolerance, Technical Correction AGENCY: Environmental Protection Agency (EPA..., ethylene oxide, fenvalerate, et al.; tolerance actions. Today's rule restores the time-limited tolerance...-3) establishing a time-limited tolerance for residues of 1-naphthaleneacetic acid ethyl ester in or...

Mercury Methylation by the Methanogen Methanospirillum hungatei

PubMed Central

Reinfelder, John R.; Hines, Mark E.

2013-01-01

Methylmercury (MeHg), a neurotoxic substance that accumulates in aquatic food chains and poses a risk to human health, is synthesized by anaerobic microorganisms in the environment. To date, mercury (Hg) methylation has been attributed to sulfate- and iron-reducing bacteria (SRB and IRB, respectively). Here we report that a methanogen, Methanospirillum hungatei JF-1, methylated Hg in a sulfide-free medium at comparable rates, but with higher yields, than those observed for some SRB and IRB. Phylogenetic analyses showed that the concatenated orthologs of the Hg methylation proteins HgcA and HgcB from M. hungatei are closely related to those from known SRB and IRB methylators and that they cluster together with proteins from eight other methanogens, suggesting that these methanogens may also methylate Hg. Because all nine methanogens with HgcA and HgcB orthologs belong to the class Methanomicrobia, constituting the late-evolving methanogenic lineage, methanogenic Hg methylation could not be considered an ancient metabolic trait. Our results identify methanogens as a new guild of Hg-methylating microbes with a potentially important role in mineral-poor (sulfate- and iron-limited) anoxic freshwater environments. PMID:23934484

Improvement of acetic acid tolerance of Saccharomyces cerevisiae using a zinc-finger-based artificial transcription factor and identification of novel genes involved in acetic acid tolerance.

PubMed

Ma, Cui; Wei, Xiaowen; Sun, Cuihuan; Zhang, Fei; Xu, Jianren; Zhao, Xinqing; Bai, Fengwu

2015-03-01

Acetic acid is present in cellulosic hydrolysate as a potent inhibitor, and the superior acetic acid tolerance of Saccharomyces cerevisiae ensures good cell viability and efficient ethanol production when cellulosic raw materials are used as substrates. In this study, a mutant strain of S. cerevisiae ATCC4126 (Sc4126-M01) with improved acetic acid tolerance was obtained through screening strains transformed with an artificial zinc finger protein transcription factor (ZFP-TF) library. Further analysis indicated that improved acetic acid tolerance was associated with improved catalase (CAT) activity. The ZFP coding sequence associated with the improved phenotype was identified, and real-time RT-PCR analysis revealed that three of the possible genes involved in the enhanced acetic acid tolerance regulated by this ZFP-TF, namely YFL040W, QDR3, and IKS1, showed decreased transcription levels in Sc4126-M01 in the presence of acetic acid, compared to those in the control strain. Sc4126-M01 mutants having QDR3 and IKS1 deletion (ΔQDR3 and ΔIKS1) exhibited higher acetic acid tolerance than the wild-type strain under acetic acid treatment. Glucose consumption rate and ethanol productivity in the presence of 5 g/L acetic acid were improved in the ΔQDR3 mutant compared to the wild-type strain. Our studies demonstrated that the synthetic ZFP-TF library can be used to improve acetic acid tolerance of S. cerevisiae and that the employment of an artificial transcription factor can facilitate the exploration of novel functional genes involved in stress tolerance of S. cerevisiae.

Hydrolysis, adsorption, and biodegradation of bensulfuron methyl under methanogenic conditions.

PubMed

Zhu, Fan-Ping; Duan, Jian-Lu; Yuan, Xian-Zheng; Shi, Xiao-Shuang; Han, Zhen-Lian; Wang, Shu-Guang

2018-05-01

Bensulfuron methyl (BSM), one of the most widely used herbicides in paddy soils, is frequently detected in natural and artificial aquatic systems. However, BSM transformation under methanogenic conditions has not been given sufficient attention. In this study, BSM elimination and transformation by anaerobic enrichment cultures were investigated. The results showed that BSM can be mineralized to methane through hydrolysis, adsorption, and biodegradation under a methanogenic environment. The adsorption led to protein static quenching in the extracellular polymeric substances (EPSs) of the enrichment cultures. Specifically, BSM mainly reacted with the amine, amide, amino acid, and amino sugar functional groups in proteins. BSM hydrolysis and biodegradation occurred through the breakage of the sulfonylurea bridge and sulfonyl amide linkage. The cleavage of the sulfonylurea bridge occurred in both hydrolysis and biodegradation, while the cleavage of the sulfonyl amide linkage only occurred in hydrolysis. These results elucidated the complex transformation of BSM under methanogenic conditions, which will advance the studies on sulfonylurea herbicide biotransformation and hazard assessment in the environment. Copyright © 2018 Elsevier Ltd. All rights reserved.

Effect of different ammonia sources on aceticlastic and hydrogenotrophic methanogens.

PubMed

Tian, Hailin; Fotidis, Ioannis A; Kissas, Konstantinos; Angelidaki, Irini

2018-02-01

Ammonium chloride (NH 4 Cl) was usually used as a model ammonia source to simulate ammonia inhibition during anaerobic digestion (AD) of nitrogen-rich feedstocks. However, ammonia in AD originates mainly from degradation of proteins, urea and nucleic acids, which is distinct from NH 4 Cl. Thus, in this study, the inhibitory effect of a "natural" ammonia source (urea) and NH 4 Cl, on four pure methanogenic strains (aceticlastic: Methanosarcina thermophila, Methanosarcina barkeri; hydrogenotrophic: Methanoculleus bourgensis, Methanoculleus thermophilus), was assessed under mesophilic (37 °C) and thermophilic (55 °C) conditions. The results showed that urea hydrolysis increased pH significantly to unsuitable levels for methanogenic growth, while NH 4 Cl had a negligible effect on pH. After adjusting initial pH to 7 and 8, urea was significantly stronger inhibitor with longer lag phases to methanogenesis compared to NH 4 Cl. Overall, urea seems to be more toxic on both aceticlastic and hydrogenotrophic methanogens compared to NH 4 Cl under the same total and free ammonia levels. Copyright © 2017 Elsevier Ltd. All rights reserved.

Performance of methanogenic reactors in temperature phased two-stage anaerobic digestion of swine wastewater.

PubMed

Kim, Woong; Shin, Seung Gu; Cho, Kyungjin; Lee, Changsoo; Hwang, Seokhwan

2012-12-01

The present study investigated the shifts in the chemical profiles of a two-phase anaerobic digestion system in methanogenic and acidogenic reactors for the treatment of swine wastewater. Acidogenic and methanogenic digesters were used with overall HRTs ranging from 27 to 6 d. In the optimized thermophilic/acidogenic phase throughout the entire experimental period, VS was reduced by 13.8% (1.6%); however, COD hardly decreased because of the thermophilic hydrolysis of organic materials, such as carbohydrates, proteins, and lipids, without any significant consumption of volatile fatty acids. In the methanogenic/mesophilic phase, COD was reduced by 65.8 (1.1)% compared to a 47.4 (2.9)% reduction in VS reduction efficiency with the gradual increase in methane production during a methanogenic HRT between 25 and 10 d. A high protein degradation rate was observed in the optimized acidogenic phase, which is assumed to be due to the low content of carbohydrates in raw swine wastewater as well as the readily thermophilic hydrolysis of proteins. Two-phase systems of anaerobic digestion consisting of optimized thermophilic and mesophilic methanogenic digesters showed a stable performance with respect to VS reduction efficiency with OLRs less than 3 g VS/L·d, in other words, more than 10 days of methanogenic HRT in this study. Copyright © 2012 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

Methanogenic diversity and activity in hypersaline sediments of the centre of the Napoli mud volcano, Eastern Mediterranean Sea.

PubMed

Lazar, Cassandre Sara; Parkes, R John; Cragg, Barry A; L'Haridon, Stéphane; Toffin, Laurent

2011-08-01

Submarine mud volcanoes are a significant source of methane to the atmosphere. The Napoli mud volcano, situated in the brine-impacted Olimpi Area of the Eastern Mediterranean Sea, emits mainly biogenic methane particularly at the centre of the mud volcano. Temperature gradients support the suggestion that Napoli is a cold mud volcano with moderate fluid flow rates. Biogeochemical and molecular genetic analyses were carried out to assess the methanogenic activity rates, pathways and diversity in the hypersaline sediments of the centre of the Napoli mud volcano. Methylotrophic methanogenesis was the only significant methanogenic pathway in the shallow sediments (0-40 cm) but was also measured throughout the sediment core, confirming that methylotrophic methanogens could be well adapted to hypersaline environments. Hydrogenotrophic methanogenesis was the dominant pathway below 50 cm; however, low rates of acetoclastic methanogenesis were also present, even in sediment layers with the highest salinity, showing that these methanogens can thrive in this extreme environment. PCR-DGGE and methyl coenzyme M reductase gene libraries detected sequences affiliated with anaerobic methanotrophs (mainly ANME-1) as well as Methanococcoides methanogens. Results show that the hypersaline conditions in the centre of the Napoli mud volcano influence active biogenic methane fluxes and methanogenic/methylotrophic diversity. © 2011 Society for Applied Microbiology and Blackwell Publishing Ltd.

Plane of nutrition affects the phylogenetic diversity and relative abundance of transcriptionally active methanogens in the bovine rumen.

PubMed

McGovern, Emily; McCabe, Matthew S; Cormican, Paul; Popova, Milka; Keogh, Kate; Kelly, Alan K; Kenny, David A; Waters, Sinead M

2017-10-12

Methane generated during enteric fermentation in ruminant livestock species is a major contributor to global anthropogenic greenhouse gas emissions. A period of moderate feed restriction followed by ad libitum access to feed is widely applied in cattle management to exploit the animal's compensatory growth potential and reduce feed costs. In the present study, we utilised microbial RNA from rumen digesta samples to assess the phylogenetic diversity of transcriptionally active methanogens from feed-restricted and non-restricted animals. To determine the contribution of different rumen methanogens to methanogenesis during dietary restriction of cattle, we conducted high-throughput mcrA cDNA amplicon sequencing on an Illumina MiSeq and analysed both the abundance and phylogenetic origin of different mcrA cDNA sequences. When compared to their unrestricted contemporaries, in feed-restricted animals, the methanogenic activity, based on mcrA transcript abundance, of Methanobrevibacter gottschalkii clade increased while the methanogenic activity of the Methanobrevibacter ruminantium clade and members of the Methanomassiliicoccaceae family decreased. This study shows that the quantity of feed consumed can evoke large effects on the composition of methanogenically active species in the rumen of cattle. These data potentially have major implications for targeted CH 4 mitigation approaches such as anti-methanogen vaccines and/or tailored dietary management.

Metacognitive self-reflectivity moderates the relationship between distress tolerance and empathy in schizophrenia.

PubMed

Bonfils, Kelsey A; Minor, Kyle S; Leonhardt, Bethany L; Lysaker, Paul H

2018-07-01

Deficits in empathy seen in schizophrenia are thought to play a major role in the social dysfunction seen in the disorder. However, little work has investigated potential determinants of empathic deficits. This study aimed to fill that gap by examining the effects of two variables on empathy - distress tolerance and metacognitive self-reflectivity. Fifty-four people with schizophrenia-spectrum disorders receiving services at an urban VA or community mental health center were assessed for empathy, metacognition, and distress tolerance. Bivariate correlations and moderation methods were used to ascertain associations amongst these variables and examine interactions. Results revealed that, against hypotheses, empathy was not related at the bivariate level to either distress tolerance or metacognitive self-reflectivity. However, consistent with hypotheses, moderation analyses revealed that participants with higher self-reflectivity showed no relationship between distress tolerance and empathy, while those with lower self-reflectivity showed a relationship such that reduced ability to tolerate distress predicted reduced empathy. Taken together, results of this study suggest that lack of distress tolerance can negatively affect empathy in people with schizophrenia with lesser capacity for metacognitive self-reflection; thus, fostering self-reflectivity may help overcome that negative impact. Future work is needed investigating the impact of metacognitively-tailored interventions on empathy in this population. Copyright © 2018. Published by Elsevier B.V.

Combination therapy with retinaldehyde (0.1%) glycolic acid (6%) and efectiose (0.1%) in mild to moderate acne vulgaris during the period of sun exposure--efficacy and skin tolerability.

PubMed

Masini, F; Ricci, F; Fossati, B; Frascione, P; Capizzi, R; De Waure, C; Guerriero, C

2014-08-01

Acne vulgaris is the most common disease of the adolescence age (70-94%). Main topical treatments for acne vulgaris are retinoids, benzoyl peroxide and antibiotics in mono or combination therapy. Topical retinoids, some antibiotics and antiseptics although effective on acne lesions, can due photosensitivity or make the skin more sensitive to the sun. Our study is aimed to evaluate the efficacy and tolerability of a combination therapy with Retinaldheyde (0.1%), Glycolic acid (6%) and Efectiose (0.1%) (RGE) cream in patients affected by acne vulgaris, during the lasting period of sun exposure. We retrospectively observed 30 patients of Central Italy with mild or moderate acne between April and September. All the patients selected underwent only therapy with RGE cream once a day in the evening for 8 weeks, while in the morning they just applied SPF 50 sunscreen. We evaluate the efficacy at 30 and 60 days with the "Global Evaluation Scale" (GES) and the tolerability with a 0-3 qualitative scale. The mean GES value showed a statistically significant reduction: 1.83 (SD 0.83) at baseline 1.57 (SD 0.77) and 0.90 (SD 0.76) respectively at 30 and 60 days (p < 0.01). Side effects were very uncommon. Topical treatments with retinoids, antibiotics and antiseptics can be associated with an increased occurrence of facial dryness and erythema restricting their use in sun exposure period. RGE cream has shown a good skin tolerability and efficacy, so it can be considerate an effective maintaining therapy to treat mild to moderate acne during the sun exposure period in which retinoids, antibiotics or antiseptic treatments are not recommended.

Methanogenic community development in anaerobic granular bioreactors treating trichloroethylene (TCE)-contaminated wastewater at 37 °C and 15 °C.

PubMed

Siggins, Alma; Enright, Anne-Marie; O'Flaherty, Vincent

2011-04-01

Four expanded granular sludge bed (EGSB) bioreactors were seeded with a mesophilically-grown granular sludge and operated in duplicate for mesophilic (37 °C; R1 & R2) and low- (15°; R3 & R4) temperature treatment of a synthetic volatile fatty acid (VFA) based wastewater (3 kg COD m(-3) d(-1)) with one of each pair (R1 & R3) supplemented with increasing concentrations of trichloroethylene (TCE; 10, 20, 40, 60 mg l(-1)) and one acting as a control. Bioreactor performance was evaluated by % COD removal efficiency and % biogas methane (CH(4)) content. Quantitative Polymerase Chain Reaction (qPCR) was used to investigate the methanogenic community composition and dynamics in the bioreactors during the trial, while specific methanogenic activity (SMA) and toxicity assays were utilized to investigate the activity and TCE/dichloroethylene (DCE) toxicity thresholds of key trophic groups, respectively. At both 37 °C and 15 °C, TCE levels of 60 mg l(-1) resulted in the decline of % COD removal efficiencies to 29% (Day 235) and 37% (Day 238), respectively, and in % biogas CH(4) to 54% (Day 235) and 5% (Day 238), respectively. Despite the inhibitory effect of TCE on the anaerobic digestion process, the main drivers influencing methanogenic community development, as determined by qPCR and Non-metric multidimensional scaling analysis, were (i) wastewater composition and (ii) operating temperature. At the apical TCE concentration both SMA and qPCR of methanogenic archaea suggested that acetoclastic methanogens were somewhat inhibited by the presence of TCE and/or its degradation derivatives, while competition by dechlorinating organisms may have limited the availability of H(2) for hydrogenotrophic methanogenesis. In addition, there appeared to be an inverse correlation between SMA levels and TCE tolerance, a finding that was supported by the analysis of the inhibitory effect of TCE on two additional biomass sources. The results indicate that low-temperature anaerobic

Potassium extrusion by the moderately halophilic and alkaliphilic methanogen methanolobus taylorii GS-16 and homeostasis of cytosolic pH.

PubMed Central

Ni, S; Boone, J E; Boone, D R

1994-01-01

Methanolobus taylorii GS-16, a moderately halophilic and alkaliphilic methanogen, grows over a wide pH range, from 6.8 to 9.0. Cells suspended in medium with a pH above 8.2 reversed their transmembrane pH gradient (delta pH), making their cytosol more acidic than the medium. The decreased energy in the proton motive force due to the reversed delta pH was partly compensated by an increased electric membrane potential (delta psi). The cytosolic acidification by M. taylorii at alkaline pH values was accompanied by K+ extrusion. The cytosolic K+ concentration was 110 mM in cells suspended at pH 8.7, but it was 320 mM in cells suspended at neutral pH values. High external K+ concentrations (210 mM or higher) inhibited the growth of M. taylorii at alkaline pH values, perhaps by preventing K+ extrusion. Cells suspended at pH 8.5 and 300 mM external K+ failed to acidify their cytosol. The key observation indicative of the involvement of K+ transport in cytosolic acidification was that valinomycin (0.8 microM), a K+ uniporter, inhibited the growth of M. taylorii only at alkaline pH values. Experiments with resting cells indicated that at alkaline pH values valinomycin uncoupled catabolic reactions from ATP synthesis. Thus, K+/H+ antiport activity was proposed to account for the K+ extrusion and the uncoupling effect of valinomycin at alkaline pH values. Such antiport activity was demonstrated by the sharp drop in pH of the bulk medium of the cell suspension upon the addition of 0.1 M KCl. The antiporter appeared to be active only at alkaline pH values, which was in accordance with a possible role in pH homeostasis by M. taylorii growing at alkaline pH values. PMID:7961499

40 CFR 180.325 - 2-(m-Chlorophenoxy) propionic acid; tolerances for residues.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 23 2010-07-01 2010-07-01 false 2-(m-Chlorophenoxy) propionic acid... Tolerances § 180.325 2-(m-Chlorophenoxy) propionic acid; tolerances for residues. (a) General. A tolerance is established for negligible residues of the plant regulator 2-(m-chlorophenoxy) propionic acid from application...

Safety and tolerance of ester-C compared with regular ascorbic acid.

PubMed

Gruenwald, Joerg; Graubaum, Hans-Joachim; Busch, Regina; Bentley, Christine

2006-01-01

The goal of this randomized, double-blind crossover clinical trial in 50 healthy volunteers sensitive to acidic foods was to evaluate whether Ester-C calcium ascorbate causes fewer epigastric adverse effects than are produced by regular ascorbic acid (AA). Volunteers were randomly separated into 2 groups of 25. The study comprised an observation period of 9 days (phase 1 medication for 3 consecutive days, washout phase for 3 consecutive days, phase 2 medication for 3 consecutive days). Participants took 1000 mg vitamin C as Ester-C during phase 1 of the study followed by 1000 mg of vitamin C as AA during phase 2, or vice versa. During the course of the study, 3 examinations for the evaluation of epigastric adverse effects were performed (on days 0, 3, and 9). Participants used a diary to record epigastric adverse effects on a daily basis. In total, 28 (56%) of 50 participants reported 88 epigastric adverse effects of mild to moderate intensity. Of these 88 adverse effects, 33 (37.5%) occurred after intake of Ester-C and 55 (62.5%) were noted after intake of AA. The tolerability of Ester-C was rated "very good" by 72% of participants, whereas AA was rated "very good" by only 54%. This difference is statistically significant (P<.05). Investigators concluded that Ester-C compared with AA caused significantly fewer epigastric adverse effects in participants sensitive to acidic foods and that Ester-C is much better tolerated.

Estimation of methanogen biomass via quantitation of coenzyme M

USGS Publications Warehouse

Elias, Dwayne A.; Krumholz, Lee R.; Tanner, Ralph S.; Suflita, Joseph M.

1999-01-01

Determination of the role of methanogenic bacteria in an anaerobic ecosystem often requires quantitation of the organisms. Because of the extreme oxygen sensitivity of these organisms and the inherent limitations of cultural techniques, an accurate biomass value is very difficult to obtain. We standardized a simple method for estimating methanogen biomass in a variety of environmental matrices. In this procedure we used the thiol biomarker coenzyme M (CoM) (2-mercaptoethanesulfonic acid), which is known to be present in all methanogenic bacteria. A high-performance liquid chromatography-based method for detecting thiols in pore water (A. Vairavamurthy and M. Mopper, Anal. Chim. Acta 78:363–370, 1990) was modified in order to quantify CoM in pure cultures, sediments, and sewage water samples. The identity of the CoM derivative was verified by using liquid chromatography-mass spectroscopy. The assay was linear for CoM amounts ranging from 2 to 2,000 pmol, and the detection limit was 2 pmol of CoM/ml of sample. CoM was not adsorbed to sediments. The methanogens tested contained an average of 19.5 nmol of CoM/mg of protein and 0.39 ± 0.07 fmol of CoM/cell. Environmental samples contained an average of 0.41 ± 0.17 fmol/cell based on most-probable-number estimates. CoM was extracted by using 1% tri-(N)-butylphosphine in isopropanol. More than 90% of the CoM was recovered from pure cultures and environmental samples. We observed no interference from sediments in the CoM recovery process, and the method could be completed aerobically within 3 h. Freezing sediment samples resulted in 46 to 83% decreases in the amounts of detectable CoM, whereas freezing had no effect on the amounts of CoM determined in pure cultures. The method described here provides a quick and relatively simple way to estimate methanogenic biomass.

Characterization of the methanogen community in a household anaerobic digester fed with swine manure in China.

PubMed

Qin, Huibin; Lang, Huihua; Yang, Hongjiang

2013-09-01

Household anaerobic digesters have been installed across rural China for biogas production, but information on methanogen community structure in these small biogas units is sparsely available. By creating clone libraries for 16S rRNA and methyl coenzyme M reductase alpha subunit (mcrA) genes, we investigated the methanogenic consortia in a household biogas digester treating swine manure. Operational taxonomic units (OTUs) were defined by comparative sequence analysis, seven OTUs were identified in the 16S rRNA gene library, and ten OTUs were identified in the mcrA gene library. Both libraries were dominated by clones highly related to the type strain Methanocorpusculum labreanum Z, 64.0 % for 16S rRNA gene clones and 64.3 % for mcrA gene clones. Additionally, gas chromatography assays showed that formic acid was 84.54 % of the total volatile fatty acids and methane was 57.20 % of the biogas composition. Our results may help further isolation and characterization of methanogenic starter strains for industrial biogas production.

Methanogenic activity in plankton samples and fish intestines A mechanism for in situ methanogenesis in oceanic surface waters

USGS Publications Warehouse

Oremland, Ronald S.

1979-01-01

When plankton samples were incubated anaerobically with a cysteine-sulfide reducing agent, pronounced methane evolution occurred. This activity was inhibited by air, CHCl3, C2H2, and 2-bromoethanesulfonic acid. Adding [14C]CO32− resulted in accumulation of [14C]CH4. Portions of the digestive tracts of three fishes were incubated in methanogenic media, and two of the samples showed the presence of methanogenic bacteria.

Ruminal fermentation of anti-methanogenic nitrate- and nitro-containing forages in vitro

USDA-ARS?s Scientific Manuscript database

Nitrate, 3-nitro-1-propionic acid (NPA), and 3-nitro-1-propanol (NPOH) can accumulate in forages and be poisonous to animals if fed at high enough amounts. These chemicals are also recognized as potent anti-methanogenic compounds, but plants naturally containing these chemicals have been studied li...

New approach to control the methanogenic reactor of a two-phase anaerobic digestion system.

PubMed

von Sachs, Jürgen; Meyer, Ulrich; Rys, Paul; Feitkenhauer, Heiko

2003-03-01

A new control strategy for the methanogenic reactor of a two-phase anaerobic digestion system has been developed and successfully tested on the laboratory scale. The control strategy serves the purpose to detect inhibitory effects and to achieve good conversion. The concept is based on the idea that volatile fatty acids (VFA) can be measured in the influent of the methanogenic reactor by means of titration. Thus, information on the output (methane production) and input of the methanogenic reactor is available, and a (carbon) mass balance can be obtained. The control algorithm comprises a proportional/integral structure with the ratio of (a) the methane production rate measured online and (b) a maximum methane production rate expected (derived from the stoichiometry) as a control variable. The manipulated variable is the volumetric feed rate. Results are shown for an experiment with VFA (feed) concentration ramps and for experiments with sodium chloride as inhibitor.

40 CFR 180.1090 - Lactic acid; exemption from the requirement of a tolerance.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 24 2011-07-01 2011-07-01 false Lactic acid; exemption from the requirement of a tolerance. 180.1090 Section 180.1090 Protection of Environment ENVIRONMENTAL PROTECTION... Exemptions From Tolerances § 180.1090 Lactic acid; exemption from the requirement of a tolerance. Lactic acid...

40 CFR 180.1090 - Lactic acid; exemption from the requirement of a tolerance.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 23 2010-07-01 2010-07-01 false Lactic acid; exemption from the requirement of a tolerance. 180.1090 Section 180.1090 Protection of Environment ENVIRONMENTAL PROTECTION... Exemptions From Tolerances § 180.1090 Lactic acid; exemption from the requirement of a tolerance. Lactic acid...

40 CFR 180.1090 - Lactic acid; exemption from the requirement of a tolerance.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 25 2012-07-01 2012-07-01 false Lactic acid; exemption from the requirement of a tolerance. 180.1090 Section 180.1090 Protection of Environment ENVIRONMENTAL PROTECTION... Exemptions From Tolerances § 180.1090 Lactic acid; exemption from the requirement of a tolerance. Lactic acid...

40 CFR 180.1090 - Lactic acid; exemption from the requirement of a tolerance.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 24 2014-07-01 2014-07-01 false Lactic acid; exemption from the requirement of a tolerance. 180.1090 Section 180.1090 Protection of Environment ENVIRONMENTAL PROTECTION... Exemptions From Tolerances § 180.1090 Lactic acid; exemption from the requirement of a tolerance. Lactic acid...

40 CFR 180.1090 - Lactic acid; exemption from the requirement of a tolerance.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 25 2013-07-01 2013-07-01 false Lactic acid; exemption from the requirement of a tolerance. 180.1090 Section 180.1090 Protection of Environment ENVIRONMENTAL PROTECTION... Exemptions From Tolerances § 180.1090 Lactic acid; exemption from the requirement of a tolerance. Lactic acid...

40 CFR 180.180 - Orthoarsenic acid; tolerance for residues.

Code of Federal Regulations, 2010 CFR

2010-07-01

...) PESTICIDE PROGRAMS TOLERANCES AND EXEMPTIONS FOR PESTICIDE CHEMICAL RESIDUES IN FOOD Specific Tolerances..., 1995, for combined As 2O 3 is established for residues of the defoliant orthoarsenic acid in or on the...

40 CFR 180.180 - Orthoarsenic acid; tolerance for residues.

Code of Federal Regulations, 2011 CFR

2011-07-01

...) PESTICIDE PROGRAMS TOLERANCES AND EXEMPTIONS FOR PESTICIDE CHEMICAL RESIDUES IN FOOD Specific Tolerances..., 1995, for combined As 2O 3 is established for residues of the defoliant orthoarsenic acid in or on the...

40 CFR 180.331 - 4-(2,4-Dichlorophenoxy) butyric acid; tolerances for residues.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 23 2010-07-01 2010-07-01 false 4-(2,4-Dichlorophenoxy) butyric acid... Tolerances § 180.331 4-(2,4-Dichlorophenoxy) butyric acid; tolerances for residues. (a) General. Tolerances are established for residues of the herbicide 4-(2,4-dichlorophenoxy) butyric acid (2,4-DB), both free...

40 CFR 180.331 - 4-(2,4-Dichlorophenoxy) butyric acid; tolerances for residues.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 25 2013-07-01 2013-07-01 false 4-(2,4-Dichlorophenoxy) butyric acid... Tolerances § 180.331 4-(2,4-Dichlorophenoxy) butyric acid; tolerances for residues. (a) General. Tolerances are established for residues of the herbicide 4-(2,4-dichlorophenoxy) butyric acid (2,4-DB), both free...

40 CFR 180.331 - 4-(2,4-Dichlorophenoxy) butyric acid; tolerances for residues.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 24 2011-07-01 2011-07-01 false 4-(2,4-Dichlorophenoxy) butyric acid... Tolerances § 180.331 4-(2,4-Dichlorophenoxy) butyric acid; tolerances for residues. (a) General. Tolerances are established for residues of the herbicide 4-(2,4-dichlorophenoxy) butyric acid (2,4-DB), both free...

40 CFR 180.331 - 4-(2,4-Dichlorophenoxy) butyric acid; tolerances for residues.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 24 2014-07-01 2014-07-01 false 4-(2,4-Dichlorophenoxy) butyric acid... Tolerances § 180.331 4-(2,4-Dichlorophenoxy) butyric acid; tolerances for residues. (a) General. Tolerances are established for residues of the herbicide 4-(2,4-dichlorophenoxy) butyric acid (2,4-DB), both free...

40 CFR 180.331 - 4-(2,4-Dichlorophenoxy) butyric acid; tolerances for residues.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 25 2012-07-01 2012-07-01 false 4-(2,4-Dichlorophenoxy) butyric acid... Tolerances § 180.331 4-(2,4-Dichlorophenoxy) butyric acid; tolerances for residues. (a) General. Tolerances are established for residues of the herbicide 4-(2,4-dichlorophenoxy) butyric acid (2,4-DB), both free...

Randomized study comparing the efficacy and tolerance of a lipohydroxy acid shampoo to a ciclopiroxolamine shampoo in the treatment of scalp seborrheic dermatitis.

PubMed

Seite, Sophie; Rougier, André; Talarico, Sergio

2009-12-01

The success of a dandruff treatment depends not only on the ability of a shampoo to control dandruff, but also on patient compliance, which is closely linked to the cosmetic attributes of the product. The aim of this study was to compare efficacy, tolerance, and cosmetic properties of a LHA Shampoo [containing 0.1% lipohydroxy acid (LHA) and 1.3% salicylic acid] to a CPO shampoo [containing 1.5% ciclopiroxolamine (CPO), 3% salicylic acid, and 0.5% menthol] in subjects with seborrheic dermatitis (SD) of the scalp. One hundred subjects with mild to moderate scalp SD were randomized to receive either the LHA shampoo or the CPO shampoo every 2 days for 4 weeks. Efficacy and tolerance were evaluated at days 0, 14, and 28. The LHA and the CPO shampoo both decreased symptoms of scale, erythema, itching, cutaneous discomfort, and dryness from baseline to day 28. A higher percentage of patients showed improvement in the group treated with the LHA formulation than in the group treated with the CPO formulation, but the difference did not reach statistical significance. At day 28, the tolerance and the global efficacy of the LHA shampoo were significantly better (P = 0.03 and P = 0.01, respectively) than those of the CPO shampoo. Furthermore, the cosmetic acceptability was better or significantly better for all the endpoints evaluated for the LHA shampoo (P = 0.02 for cleaning, P = 0.04 for lathering). In conclusion, these results demonstrated that the lipohydroxy acid shampoo evaluated in this study is a more convenient, efficient, safe, and well-tolerated cosmetic treatment for mild-to-moderate seborrheic dermatitis of the scalp than a ciclopiroxolamine shampoo.

Formation of methane and carbon dioxide from dimethylselenide in anoxic sediments and by a methanogenic bacterium

USGS Publications Warehouse

Oremland, Ronald S.; Zehr, Jon P.

1986-01-01

Anaerobic San Francisco Bay salt marsh sediments rapidly metabolized [14C]dimethylselenide (DMSe) to 14CH4 and 14CO2. Addition of selective inhibitors (2-bromoethanesulfonic acid or molybdate) to these sediments indicated that both methanogenic and sulfate-respiring bacteria could degrade DMSe to gaseous products. However, sediments taken from the selenium-contaminated Kesterson Wildlife Refuge produced only 14CO2 from [14C]DMSe, implying that methanogens were not important in the Kesterson samples. A pure culture of a dimethylsulfide (DMS)-grown methylotrophic methanogen converted [14C]DMSe to 14CH4 and14CO2. However, the organism could not grow on DMSe. Addition of DMS to either sediments or the pure culture retarded the metabolism of DMSe. This effect appeared to be caused by competitive inhibition, thereby indicating a common enzyme system for DMS and DMSe metabolism. DMSe appears to be degraded as part of the DMS pool present in anoxic environments. These results suggest that methylotrophic methanogens may demethylate methylated forms of other metals and metalloids found in nature.

Trace Elements Induce Predominance among Methanogenic Activity in Anaerobic Digestion

PubMed Central

Wintsche, Babett; Glaser, Karin; Sträuber, Heike; Centler, Florian; Liebetrau, Jan; Harms, Hauke; Kleinsteuber, Sabine

2016-01-01

Trace elements (TE) play an essential role in all organisms due to their functions in enzyme complexes. In anaerobic digesters, control, and supplementation of TEs lead to stable and more efficient methane production processes while TE deficits cause process imbalances. However, the underlying metabolic mechanisms and the adaptation of the affected microbial communities to such deficits are not yet fully understood. Here, we investigated the microbial community dynamics and resulting process changes induced by TE deprivation. Two identical lab-scale continuous stirred tank reactors fed with distiller’s grains and supplemented with TEs (cobalt, molybdenum, nickel, tungsten) and a commercial iron additive were operated in parallel. After 72 weeks of identical operation, the feeding regime of one reactor was changed by omitting TE supplements and reducing the amount of iron additive. Both reactors were operated for further 21 weeks. Various process parameters (biogas production and composition, total solids and volatile solids, TE concentration, volatile fatty acids, total ammonium nitrogen, total organic acids/alkalinity ratio, and pH) and the composition and activity of the microbial communities were monitored over the total experimental time. While the methane yield remained stable, the concentrations of hydrogen sulfide, total ammonia nitrogen, and acetate increased in the TE-depleted reactor compared to the well-supplied control reactor. Methanosarcina and Methanoculleus dominated the methanogenic communities in both reactors. However, the activity ratio of these two genera was shown to depend on TE supplementation explainable by different TE requirements of their energy conservation systems. Methanosarcina dominated the well-supplied anaerobic digester, pointing to acetoclastic methanogenesis as the dominant methanogenic pathway. Under TE deprivation, Methanoculleus and thus hydrogenotrophic methanogenesis was favored although Methanosarcina was not overgrown

Identification of Rhizobium phaseoli Strains That Are Tolerant or Sensitive to Soil Acidity

PubMed Central

Lowendorf, Henry S.; Alexander, Martin

1983-01-01

A study was conducted to determine whether the survival of Rhizobium phaseoli in acid soils could be predicted on the basis of the tolerance of the organism to acidity in culture. Of 16 strains tested, all grew in culture at pH 4.6, but only those that grew at pH 3.8 survived in soils having pH values of 4.1 to 4.6. Strains that tolerated the lowest pH values in culture were tolerant of the highest aluminum concentrations. In one acid soil, an acid-tolerant strain was unable to survive in numbers greater than 100/g, but the poor survival was not related to the level of extractable aluminum or manganese in the soil. Reproduction of an acid-tolerant strain of R. phaseoli was enhanced in the rhizosphere of Phaseolus vulgaris in both acid and limed soils, but stimulation of an acid-sensitive strain by the plant occurred only in the limed soil. These results indicate that cultural tests can be used to predict the ability of R. phaseoli to survive in acid soil. PMID:16346239

Application of Methanobrevibacter acididurans in anaerobic digestion.

PubMed

Savant, D V; Ranade, D R

2004-01-01

To operate anaerobic digesters successfully under acidic conditions, hydrogen utilizing methanogens which can grow efficiently at low pH and tolerate high volatile fatty acids (VFA) are desirable. An acid tolerant hydrogenotrophic methanogen viz. Methanobrevibacter acididurans isolated from slurry of an anaerobic digester running on alcohol distillery wastewater has been described earlier by this lab. This organism could grow optimally at pH 6.0. In the experiments reported herein, M. acididurans showed better methanogenesis under acidic conditions with high VFA, particularly acetate, than Methanobacterium bryantii, a common hydrogenotrophic inhabitant of anaerobic digesters. Addition of M. acididurans culture to digesting slurry of acidogenic as well as methanogenic digesters running on distillery wastewater showed increase in methane production and decrease in accumulation of volatile fatty acids. The results proved the feasibility of application of M. acididurans in anaerobic digesters.

Low Pressure Tolerance by Methanogens in an Aqueous Environment: Implications for Subsurface Life on Mars.

PubMed

Mickol, R L; Kral, T A

2017-12-01

The low pressure at the surface of Mars (average: 6 mbar) is one potentially biocidal factor that any extant life on the planet would need to endure. Near subsurface life, while shielded from ultraviolet radiation, would also be exposed to this low pressure environment, as the atmospheric gas-phase pressure increases very gradually with depth. Few studies have focused on low pressure as inhibitory to the growth or survival of organisms. However, recent work has uncovered a potential constraint to bacterial growth below 25 mbar. The study reported here tested the survivability of four methanogen species (Methanothermobacter wolfeii, Methanosarcina barkeri, Methanobacterium formicicum, Methanococcus maripaludis) under low pressure conditions approaching average martian surface pressure (6 mbar - 143 mbar) in an aqueous environment. Each of the four species survived exposure of varying length (3 days - 21 days) at pressures down to 6 mbar. This research is an important stepping-stone to determining if methanogens can actively metabolize/grow under these low pressures. Additionally, the recently discovered recurring slope lineae suggest that liquid water columns may connect the surface to deeper levels in the subsurface. If that is the case, any organism being transported in the water column would encounter the changing pressures during the transport.

Low Pressure Tolerance by Methanogens in an Aqueous Environment: Implications for Subsurface Life on Mars

NASA Astrophysics Data System (ADS)

Mickol, R. L.; Kral, T. A.

2017-12-01

The low pressure at the surface of Mars (average: 6 mbar) is one potentially biocidal factor that any extant life on the planet would need to endure. Near subsurface life, while shielded from ultraviolet radiation, would also be exposed to this low pressure environment, as the atmospheric gas-phase pressure increases very gradually with depth. Few studies have focused on low pressure as inhibitory to the growth or survival of organisms. However, recent work has uncovered a potential constraint to bacterial growth below 25 mbar. The study reported here tested the survivability of four methanogen species ( Methanothermobacter wolfeii, Methanosarcina barkeri, Methanobacterium formicicum, Methanococcus maripaludis) under low pressure conditions approaching average martian surface pressure (6 mbar - 143 mbar) in an aqueous environment. Each of the four species survived exposure of varying length (3 days - 21 days) at pressures down to 6 mbar. This research is an important stepping-stone to determining if methanogens can actively metabolize/grow under these low pressures. Additionally, the recently discovered recurring slope lineae suggest that liquid water columns may connect the surface to deeper levels in the subsurface. If that is the case, any organism being transported in the water column would encounter the changing pressures during the transport.

Study of methanogen communities associated with different rumen protozoal populations

PubMed Central

Belanche, Alejandro; de la Fuente, Gabriel; Newbold, Charles J

2014-01-01

Protozoa-associated methanogens (PAM) are considered one of the most active communities in the rumen methanogenesis. This experiment investigated whether methanogens are sequestrated within rumen protozoa, and structural differences between rumen free-living methanogens and PAM. Rumen protozoa were harvested from totally faunated sheep, and six protozoal fractions (plus free-living microorganisms) were generated by sequential filtration. Holotrich-monofaunated sheep were also used to investigate the holotrich-associated methanogens. Protozoal size determined the number of PAM as big protozoa had 1.7–3.3 times more methanogen DNA than smaller protozoa, but also more endosymbiotic bacteria (2.2- to 3.5-fold times). Thus, similar abundance of methanogens with respect to total bacteria were observed across all protozoal fractions and free-living microorganisms, suggesting that methanogens are not accumulated within rumen protozoa in a greater proportion to that observed in the rumen as a whole. All rumen methanogen communities had similar diversity (22.2 ± 3.4 TRFs). Free-living methanogens composed a conserved community (67% similarity within treatment) in the rumen with similar diversity but different structures than PAM (P < 0.05). On the contrary, PAM constituted a more variable community (48% similarity), which differed between holotrich and total protozoa (P < 0.001). Thus, PAM constitutes a community, which requires further investigation as part of methane mitigation strategies. PMID:25195951

Heavy-machinery traffic impacts methane emissions as well as methanogen abundance and community structure in oxic forest soils.

PubMed

Frey, Beat; Niklaus, Pascal A; Kremer, Johann; Lüscher, Peter; Zimmermann, Stephan

2011-09-01

Temperate forest soils are usually efficient sinks for the greenhouse gas methane, at least in the absence of significant amounts of methanogens. We demonstrate here that trafficking with heavy harvesting machines caused a large reduction in CH(4) consumption and even turned well-aerated forest soils into net methane sources. In addition to studying methane fluxes, we investigated the responses of methanogens after trafficking in two different forest sites. Trafficking generated wheel tracks with different impact (low, moderate, severe, and unaffected). We found that machine passes decreased the soils' macropore space and lowered hydraulic conductivities in wheel tracks. Severely compacted soils yielded high methanogenic abundance, as demonstrated by quantitative PCR analyses of methyl coenzyme M reductase (mcrA) genes, whereas these sequences were undetectable in unaffected soils. Even after a year after traffic compression, methanogen abundance in compacted soils did not decline, indicating a stability of methanogens here over time. Compacted wheel tracks exhibited a relatively constant community structure, since we found several persisting mcrA sequence types continuously present at all sampling times. Phylogenetic analysis revealed a rather large methanogen diversity in the compacted soil, and most mcrA gene sequences were mostly similar to known sequences from wetlands. The majority of mcrA gene sequences belonged either to the order Methanosarcinales or Methanomicrobiales, whereas both sites were dominated by members of the families Methanomicrobiaceae Fencluster, with similar sequences obtained from peatland environments. The results show that compacting wet forest soils by heavy machinery causes increases in methane production and release.

Generation and Characterization of Acid Tolerant Fibrobacter succinogenes S85

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wu, Chia-wei; Spike, Thomas; Klingeman, Dawn M.

Microorganisms are key components for plant biomass breakdown within rumen environments. Fibrobacter succinogenes have been identified as being active and dominant cellulolytic members of the rumen. In this study, F. succinogenes type strain S85 was adapted for steady state growth in continuous culture at pH 5.75 and confirmed to grow in the range of pH 5.60–5.65, which is lower than has been reported previously. Wild type and acid tolerant strains digested corn stover with equal efficiency in batch culture at low pH. RNA-seq analysis revealed 268 and 829 genes were differentially expressed at pH 6.10 and 5.65 compared to pHmore » 6.70, respectively. Resequencing analysis identified seven single nucleotide polymorphisms (SNPs) in the sufD, yidE, xylE, rlmM, mscL and dosC genes of acid tolerant strains. Due to the absence of a F. succinogenes genetic system, homologues in Escherichia coli were mutated and complemented and the resulting strains were assayed for acid survival. Complementation with wild-type or acid tolerant F. succinogenes sufD restored E. coli wild-type levels of acid tolerance, suggesting a possible role in acid homeostasis. Here, recent genetic engineering developments need to be adapted and applied in F. succinogenes to further our understanding of this bacterium.« less

Generation and Characterization of Acid Tolerant Fibrobacter succinogenes S85

DOE PAGES

Wu, Chia-wei; Spike, Thomas; Klingeman, Dawn M.; ...

2017-05-23

Microorganisms are key components for plant biomass breakdown within rumen environments. Fibrobacter succinogenes have been identified as being active and dominant cellulolytic members of the rumen. In this study, F. succinogenes type strain S85 was adapted for steady state growth in continuous culture at pH 5.75 and confirmed to grow in the range of pH 5.60–5.65, which is lower than has been reported previously. Wild type and acid tolerant strains digested corn stover with equal efficiency in batch culture at low pH. RNA-seq analysis revealed 268 and 829 genes were differentially expressed at pH 6.10 and 5.65 compared to pHmore » 6.70, respectively. Resequencing analysis identified seven single nucleotide polymorphisms (SNPs) in the sufD, yidE, xylE, rlmM, mscL and dosC genes of acid tolerant strains. Due to the absence of a F. succinogenes genetic system, homologues in Escherichia coli were mutated and complemented and the resulting strains were assayed for acid survival. Complementation with wild-type or acid tolerant F. succinogenes sufD restored E. coli wild-type levels of acid tolerance, suggesting a possible role in acid homeostasis. Here, recent genetic engineering developments need to be adapted and applied in F. succinogenes to further our understanding of this bacterium.« less

A moderate decrease in temperature induces COR15a expression through the CBF signaling cascade and enhances freezing tolerance.

PubMed

Wang, Yi; Hua, Jian

2009-10-01

Temperature has a profound effect on plant growth and development. However, the molecular mechanisms underlying this regulation are not well understood. In particular, how moderate temperature variations are perceived and transduced inside the plant cells remains obscure. In this study, we analyzed transcriptional responses to a moderate decrease in temperature (cooling) in Arabidopsis thaliana. The cooling response involves a weaker and more transient induction of cold-induced genes, such as COR15a, than cold response. This induction probably accounts for the increase in freezing tolerance by cooling acclimation. Cooling also induces some defense response genes, and their induction, but not that of COR15a, requires the salicylic acid signaling pathway. Analysis of the regulation of COR15a reveals that cooling induction is mediated through the same C repeat/dehydration-responsive (CRT/DRE) element as cold induction. Furthermore, we identified a role for CBF1 and CBF4 in transducing signals of moderate decreases in temperature. It appears that variants of the CBF signaling cascade are utilized in cold and cooling responses, and a moderate decrease in temperature may invoke an adaptive response to prepare plants to cope with a more drastic decrease in temperature.

Robust Mercury Methylation across Diverse Methanogenic Archaea

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gilmour, Cynthia C.; Bullock, Allyson L.; McBurney, Alyssa

ABSTRACT. Methylmercury (MeHg) production was compared among nine cultured methanogenic archaea that containhgcAB, a gene pair that codes for mercury (Hg) methylation. The methanogens tested produced MeHg at inherently different rates, even when normalized to growth rate and Hg availability. Eight of the nine tested were capable of MeHg production greater than that of spent- and uninoculated-medium controls during batch culture growth.Methanococcoides methylutens, anhgcAB +strain with a fused gene pair, was unable to produce more MeHg than controls. Maximal conversion of Hg to MeHg through a full batch culture growth cycle for each species (exceptM. methylutens) ranged from 2 to >50%more » of the added Hg(II) or between 0.2 and 17 pmol of MeHg/mg of protein. Three of the species produced >10% MeHg. The ability to produce MeHg was confirmed in severalhgcAB +methanogens that had not previously been tested (Methanocella paludicolaSANAE,Methanocorpusculum bavaricum,Methanofollis liminatansGKZPZ, andMethanosphaerula palustrisE1-9c). Maximal methylation was observed at low sulfide concentrations (<100 μM) and in the presence of 0.5 to 5 mM cysteine. ForM. hollandica, the addition of up to 5 mM cysteine enhanced MeHg production and cell growth in a concentration-dependent manner. As observed for bacterial Hg methylators, sulfide inhibited MeHg production. An initial evaluation of sulfide and thiol impacts on bioavailability showed methanogens responding to Hg complexation in the same way as doDeltaproteobacteria. The mercury methylation rates of several methanogens rival those of the better-studied Hg-methylating sulfate- and iron-reducing Deltaproteobacteria. IMPORTANCE. Archaea, specifically methanogenic organisms, play a role in mercury methylation in nature, but their global importance to MeHg production and the subsequent risk to ecosystems are not known. Methanogenesis has been linked to Hg methylation in several natural habitats where methylmercury

Robust Mercury Methylation across Diverse Methanogenic Archaea

DOE PAGES

Gilmour, Cynthia C.; Bullock, Allyson L.; McBurney, Alyssa; ...

2018-04-10

ABSTRACT. Methylmercury (MeHg) production was compared among nine cultured methanogenic archaea that containhgcAB, a gene pair that codes for mercury (Hg) methylation. The methanogens tested produced MeHg at inherently different rates, even when normalized to growth rate and Hg availability. Eight of the nine tested were capable of MeHg production greater than that of spent- and uninoculated-medium controls during batch culture growth.Methanococcoides methylutens, anhgcAB +strain with a fused gene pair, was unable to produce more MeHg than controls. Maximal conversion of Hg to MeHg through a full batch culture growth cycle for each species (exceptM. methylutens) ranged from 2 to >50%more » of the added Hg(II) or between 0.2 and 17 pmol of MeHg/mg of protein. Three of the species produced >10% MeHg. The ability to produce MeHg was confirmed in severalhgcAB +methanogens that had not previously been tested (Methanocella paludicolaSANAE,Methanocorpusculum bavaricum,Methanofollis liminatansGKZPZ, andMethanosphaerula palustrisE1-9c). Maximal methylation was observed at low sulfide concentrations (<100 μM) and in the presence of 0.5 to 5 mM cysteine. ForM. hollandica, the addition of up to 5 mM cysteine enhanced MeHg production and cell growth in a concentration-dependent manner. As observed for bacterial Hg methylators, sulfide inhibited MeHg production. An initial evaluation of sulfide and thiol impacts on bioavailability showed methanogens responding to Hg complexation in the same way as doDeltaproteobacteria. The mercury methylation rates of several methanogens rival those of the better-studied Hg-methylating sulfate- and iron-reducing Deltaproteobacteria. IMPORTANCE. Archaea, specifically methanogenic organisms, play a role in mercury methylation in nature, but their global importance to MeHg production and the subsequent risk to ecosystems are not known. Methanogenesis has been linked to Hg methylation in several natural habitats where methylmercury

40 CFR 180.1188 - Gamma aminobutyric acid; exemption from the requirement of a tolerance.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 23 2010-07-01 2010-07-01 false Gamma aminobutyric acid; exemption... FOOD Exemptions From Tolerances § 180.1188 Gamma aminobutyric acid; exemption from the requirement of a tolerance. Gamma aminobutyric acid is exempt from the requirement of a tolerance on all food commodities...

A multicentre, randomized, single-blind, parallel-group study comparing the efficacy and tolerability of benzoyl peroxide 3%/clindamycin 1% with azelaic acid 20% in the topical treatment of mild-to-moderate acne vulgaris.

PubMed

Schaller, M; Sebastian, M; Ress, C; Seidel, D; Hennig, M

2016-06-01

Mild-to-moderate acne vulgaris is treated with a range of mono- and combination therapies; however, clinical evidence is still required to optimize treatment recommendations. To compare the efficacy, tolerability and safety of a combination of benzoyl peroxide 3% and clindamycin 1% (BPO + CLN) with azelaic acid 20% (AzA) for the topical treatment of mild-to-moderate acne vulgaris. This was a randomized, assessor-blinded, parallel-group, multicentre study conducted in Germany. Patients with a confirmed diagnosis of acne vulgaris, aged 12-45 years, were randomized 1 : 1 to once-daily BPO + CLN gel or twice-daily AzA cream for up to 12 weeks. The primary endpoint was the percentage change in inflammatory lesions from baseline at Week 4. Secondary endpoints included total and inflammatory lesion counts and tolerability assessments. For selected secondary endpoints, inductive statistical analysis was performed post hoc. Patient safety was assessed by adverse event (AE) monitoring. Efficacy was assessed in the modified intent-to-treat (mITT) population [patients using ≥1 dose of study medication (ITT), plus baseline and ≥1 post-baseline lesion count (n = 215)]. There was a statistically significant difference in the primary endpoint, with a median decrease of -52.6% for BPO + CLN (n = 107) vs.-38.8% for AzA (n = 108; P = 0.0004). There was also a greater difference in secondary lesion endpoints at Week 12, with a median decrease in inflammatory lesions of -78.8% and -65.3% and total lesions of -69.0% and -53.9% with BPO + CLN and AzA, respectively (both P < 0.0001). Tolerability was acceptable for both treatments. Overall, 55.6% (BPO + CLN) and 69.7% (AzA) of patients reported treatment-emergent AEs, and 15.7% and 35.8% of patients experienced application site reactions with BPO + CLN (24 events; 17 patients) and AzA (60 events; 39 patients) treatment, respectively (ITT population). BPO + CLN demonstrated greater efficacy than AzA in the treatment of mild-to-moderate

Trehalose accumulation enhances tolerance of Saccharomyces cerevisiae to acetic acid.

PubMed

Yoshiyama, Yoko; Tanaka, Koichi; Yoshiyama, Kohei; Hibi, Makoto; Ogawa, Jun; Shima, Jun

2015-02-01

Trehalose confers protection against various environmental stresses on yeast cells. In this study, trehalase gene deletion mutants that accumulate trehalose at high levels showed significant stress tolerance to acetic acid. The enhancement of trehalose accumulation can thus be considered a target in the breeding of acetic acid-tolerant yeast strains. Copyright © 2014 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

Physiological, molecular, and cellular mechanisms of impaired seawater tolerance following exposure of Atlantic salmon, Salmo salar, smolts to acid and aluminum

USGS Publications Warehouse

Monette, M.Y.; Yada, T.; Matey, V.; McCormick, S.D.

2010-01-01

We examined the physiological, molecular, and cellular mechanisms of impaired ion regulation in Atlantic salmon, Salmo salar, smolts following acute acid and aluminum (Al) exposure. Smolts were exposed to: control (pH 6.5, 3.4??gl-1 Al), acid and low Al (LAl: pH 5.4, 11??gl-1 Al), acid and moderate Al (MAl: pH 5.3, 42??gl-1 Al), and acid and high Al (HAl: pH 5.4, 56??gl-1 Al) for two and six days. At each time-point, smolts were sampled directly from freshwater treatment tanks and after a 24h seawater challenge. Exposure to acid/MAl and acid/HAl led to accumulation of gill Al, substantial alterations in gill morphology, reduced gill Na+/K+-ATPase (NKA) activity, and impaired ion regulation in both freshwater and seawater. Exposure to acid/MAl for six days also led to a decrease in gill mRNA expression of the apical Cl- channel (cystic fibrosis transmembrane conductance regulator I), increased apoptosis upon seawater exposure, an increase in the surface expression of mitochondria-rich cells (MRCs) within the filament epithelium of the gill, but reduced abundance of gill NKA-positive MRCs. By contrast, smolts exposed to acid and the lowest Al concentration exhibited minor gill Al accumulation, slight morphological modifications in the gill, and impaired seawater tolerance in the absence of a detectable effect on freshwater ion regulation. These impacts were accompanied by decreased cell proliferation, a slight increase in the surface expression of MRCs within the filament epithelium, but no impact on gill apoptosis or total MRC abundance was observed. However, MRCs in the gills of smolts exposed to acid/LAl exhibited morphological alterations including decreased size, staining intensity, and shape factor. We demonstrate that the seawater tolerance of Atlantic salmon smolts is extremely sensitive to acute exposure to acid and low levels of Al, and that the mechanisms underlying this depend on the time-course and severity of Al exposure. We propose that when smolts are

TaALMT1 promoter sequence compositions, acid tolerance, and Al tolerance in wheat cultivars and landraces from Sichuan in China.

PubMed

Han, C; Dai, S F; Liu, D C; Pu, Z J; Wei, Y M; Zheng, Y L; Wen, D J; Zhao, L; Yan, Z H

2013-11-18

Previous genetic studies on wheat from various sources have indicated that aluminum (Al) tolerance may have originated independently in USA, Brazil, and China. Here, TaALMT1 promoter sequences of 92 landraces and cultivars from Sichuan, China, were sequenced. Five promoter types (I', II, III, IV, and V) were observed in 39 cultivars, and only three promoter types (I, II, and III) were observed in 53 landraces. Among the wheat collections worldwide, only the Chinese Spring (CS) landrace native to Sichuan, China, carried the TaALMT1 promoter type III. Besides CS, two other Sichuan-bred landraces and six cultivars with TaALMT1 promoter type III were identified in this study. In the phylogenetic tree constructed based on the TaALMT1 promoter sequences, type III formed a separate branch, which was supported by a high bootstrap value. It is likely that TaALMT1 promoter type III originated from Sichuan-bred wheat landraces of China. In addition, the landraces with promoter type I showed the lowest Al tolerance among all landraces and cultivars. Furthermore, the cultivars with promoter type IV showed better Al tolerance than landraces with promoter type II. A comparison of acid tolerance and Al tolerance between cultivars and landraces showed that the landraces had better acid tolerance than the cultivars, whereas the cultivars showed better Al tolerance than the landraces. Moreover, significant difference in Al tolerance was also observed between the cultivars raised by the National Ministry of Agriculture and by Sichuan Province. Among the landraces from different regions, those from the East showed better acid tolerance and Al tolerance than those from the South and West of Sichuan. Additional Al-tolerant and acid-tolerant wheat lines were also identified.

40 CFR 180.1187 - L-glutamic acid; exemption from the requirement of a tolerance.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 23 2010-07-01 2010-07-01 false L-glutamic acid; exemption from the... Exemptions From Tolerances § 180.1187 L-glutamic acid; exemption from the requirement of a tolerance. L-glutamic acid is exempt from the requirement of a tolerance on all food commodities when used in accordance...

Exercise Self-Efficacy Moderates the Relation between Anxiety Sensitivity and Body Mass Index and Exercise Tolerance in Treatment-Seeking Smokers

PubMed Central

Farris, Samantha G.; Davis, Michelle L.; Rosenfield, David; Kauffman, Brooke Y.; Baird, Scarlett O.; Powers, Mark B.; Otto, Michael W.; Marcus, Bess H.; Church, Timothy S.; Smits, Jasper A. J.; Zvolensky, Michael J.

2016-01-01

There is little known about factors that contribute to the comorbidity of cigarette smoking and obesity. The current study sought to test whether exercise self-efficacy moderated the relation between anxiety sensitivity (fear of internal sensations) and BMI and exercise tolerance among cigarette smokers. Smokers (n = 72; 50% female; Mcpd = 19.3, SD = 10.65) were recruited to participate in a smoking cessation treatment trial. During medical screen, we measured weight, height, and exercise tolerance (functional capacity) employing a standardized maximal exercise testing protocol. After adjusting for participant sex and cigarettes per day, exercise self-efficacy moderated the association between anxiety sensitivity and BMI, such that the positive association between anxiety sensitivity and BMI was significantly stronger when exercise self-efficacy was low. The same pattern of results emerged for exercise tolerance. Exercise self-efficacy moderated the association between anxiety sensitivity and exercise tolerance, such that the negative association between anxiety sensitivity and exercise tolerance was significantly stronger when exercise self-efficacy was low. Among smokers, anxiety sensitivity may be a risk variable that, directly and indirectly in the context of low self-efficacy for exercise, causes or maintains higher body weight and lower exercise tolerance. PMID:27725844

Exercise Self-Efficacy Moderates the Relation between Anxiety Sensitivity and Body Mass Index and Exercise Tolerance in Treatment-Seeking Smokers.

PubMed

Farris, Samantha G; Davis, Michelle L; Rosenfield, David; Kauffman, Brooke Y; Baird, Scarlett O; Powers, Mark B; Otto, Michael W; Marcus, Bess H; Church, Timothy S; Smits, Jasper A J; Zvolensky, Michael J

2016-03-01

There is little known about factors that contribute to the comorbidity of cigarette smoking and obesity. The current study sought to test whether exercise self-efficacy moderated the relation between anxiety sensitivity (fear of internal sensations) and BMI and exercise tolerance among cigarette smokers. Smokers ( n = 72; 50% female; M cpd = 19.3, SD = 10.65) were recruited to participate in a smoking cessation treatment trial. During medical screen, we measured weight, height, and exercise tolerance (functional capacity) employing a standardized maximal exercise testing protocol. After adjusting for participant sex and cigarettes per day, exercise self-efficacy moderated the association between anxiety sensitivity and BMI, such that the positive association between anxiety sensitivity and BMI was significantly stronger when exercise self-efficacy was low. The same pattern of results emerged for exercise tolerance. Exercise self-efficacy moderated the association between anxiety sensitivity and exercise tolerance, such that the negative association between anxiety sensitivity and exercise tolerance was significantly stronger when exercise self-efficacy was low. Among smokers, anxiety sensitivity may be a risk variable that, directly and indirectly in the context of low self-efficacy for exercise, causes or maintains higher body weight and lower exercise tolerance.

Tolerance to acetic acid is improved by mutations of the TATA-binding protein gene.

PubMed

An, Jieun; Kwon, Hyeji; Kim, Eunjung; Lee, Young Mi; Ko, Hyeok Jin; Park, Hongjae; Choi, In-Geol; Kim, Sooah; Kim, Kyoung Heon; Kim, Wankee; Choi, Wonja

2015-03-01

Screening a library of overexpressing mutant alleles of the TATA-binding gene SPT15 yielded two Saccharomyces cerevisiae strains (MRRC 3252 and 3253) with enhanced tolerance to acetic acid. They were also tolerant to propionic acid and hydrogen peroxide. Transcriptome profile analysis identified 58 upregulated genes and 106 downregulated genes in MRRC 3252. Stress- and protein synthesis-related transcription factors were predominantly enriched in the upregulated and downregulated genes respectively. Eight deletion mutants for some of the highly downregulated genes were acetic acid-tolerant. The level of intracellular reactive oxygen species was considerably lessened in MRRC 3252 and 3253 upon exposure to acetic acid. Metabolome profile analysis revealed that intracellular concentrations of 5 and 102 metabolites were increased and decreased, respectively, in MRRC 3252, featuring a large increase of urea and a significant decrease of amino acids. The dur1/2Δmutant, in which the urea degradation gene DUR1/2 is deleted, displayed enhanced tolerance to acetic acid. Enhanced tolerance to acetic acid was also observed on the medium containing a low concentration of amino acids. Taken together, this study identified two SPT15 alleles, nine gene deletions and low concentration of amino acids in the medium that confer enhanced tolerance to acetic acid. © 2014 Society for Applied Microbiology and John Wiley & Sons Ltd.

Methanogenic degradation of acetone by an enrichment culture.

PubMed

Platen, H; Schink, B

1987-01-01

An anaerobic enrichment culture degraded 1 mol of acetone to 2 mol of methane and 1 mol of carbon dioxide. Two microorganisms were involved in this process, a filament-forming rod similar to Methanothrix sp. and an unknown rod with round to slightly pointed ends. Both organisms formed aggregates up to 300 micron in diameter. No fluorescing bacteria were observed indicating that hydrogen or formate-utilizing methanogens are not involved in this process. Acetate was utilized in this culture by the Methanothrix sp. Inhibition of methanogenesis by bromoethanesulfonic acid or acetylene decreased the acetone degradation rate drastically and led to the formation of 2 mol acetate per mol of acetone. Streptomycin completely inhibited acetone degradation, and neither acetate nor methane was formed. 14CO2 was incorporated exclusively into the C-1 atom of acetate indicating that acetone is degraded via carboxylation to an acetoacetate residue. It is concluded that acetone is degraded by a coculture of an eubacterium and an acetate-utilizing methanogen and that acetate is the only intermediate transferred between both. The energetical problems of the eubacterium converting acetone to acetate are discussed.

Nucleic acid molecules conferring enhanced ethanol tolerance and microorganisms having enhanced tolerance to ethanol

DOEpatents

Brown, Steven; Guss, Adam; Yang, Shihui; Karpinets, Tatiana; Lynd, Lee; Shao, Xiongjun

2014-01-14

The present invention provides isolated nucleic acid molecules which encode a mutant acetaldehyde-CoA/alcohol dehydrogenase or mutant alcohol dehydrogenase and confer enhanced tolerance to ethanol. The invention also provides related expression vectors, genetically engineered microorganisms having enhanced tolerance to ethanol, as well as methods of making and using such genetically modified microorganisms for production of biofuels based on fermentation of biomass materials.

Genome‐wide identification of tolerance mechanisms toward p‐coumaric acid in Pseudomonas putida

PubMed Central

Calero, Patricia; Jensen, Sheila I.; Bojanovič, Klara; Lennen, Rebecca M.; Koza, Anna

2017-01-01

Abstract The soil bacterium Pseudomonas putida KT2440 has gained increasing biotechnological interest due to its ability to tolerate different types of stress. Here, the tolerance of P. putida KT2440 toward eleven toxic chemical compounds was investigated. P. putida was found to be significantly more tolerant toward three of the eleven compounds when compared to Escherichia coli. Increased tolerance was for example found toward p‐coumaric acid, an interesting precursor for polymerization with a significant industrial relevance. The tolerance mechanism was therefore investigated using the genome‐wide approach, Tn‐seq. Libraries containing a large number of miniTn5‐Km transposon insertion mutants were grown in the presence and absence of p‐coumaric acid, and the enrichment or depletion of mutants was quantified by high‐throughput sequencing. Several genes, including the ABC transporter Ttg2ABC and the cytochrome c maturation system (ccm), were identified to play an important role in the tolerance toward p‐coumaric acid of this bacterium. Most of the identified genes were involved in membrane stability, suggesting that tolerance toward p‐coumaric acid is related to transport and membrane integrity. PMID:29131301

Methanogen community composition and rates of methane consumption in Canadian High Arctic permafrost soils.

PubMed

Allan, J; Ronholm, J; Mykytczuk, N C S; Greer, C W; Onstott, T C; Whyte, L G

2014-04-01

Increasing permafrost thaw, driven by climate change, has the potential to result in organic carbon stores being mineralized into carbon dioxide (CO2) and methane (CH4) through microbial activity. This study examines the effect of increasing temperature on community structure and metabolic activity of methanogens from the Canadian High Arctic, in an attempt to predict how warming will affect microbially controlled CH4 soil flux. In situ CO2 and CH4 flux, measured in 2010 and 2011 from ice-wedge polygons, indicate that these soil formations are a net source of CO2 emissions, but a CH4 sink. Permafrost and active layer soil samples were collected at the same sites and incubated under anaerobic conditions at warmer temperatures, with and without substrate amendment. Gas flux was measured regularly and indicated an increase in CH4 flux after extended incubation. Pyrosequencing was used to examine the effects of an extended thaw cycle on methanogen diversity and the results indicate that in situ methanogen diversity, based on the relative abundance of the 16S ribosomal ribonucleic acid (rRNA) gene associated with known methanogens, is higher in the permafrost than in the active layer. Methanogen diversity was also shown to increase in both the active layer and permafrost soil after an extended thaw. This study provides evidence that although High Arctic ice-wedge polygons are currently a sink for CH4, higher arctic temperatures and anaerobic conditions, a possible result of climate change, could result in this soil becoming a source for CH4 gas flux. © 2013 Society for Applied Microbiology and John Wiley & Sons Ltd.

Correlation between oxalic acid production and copper tolerance in Wolfiporia cocos

Treesearch

C. A. Clausen; Frederick Green; B. M. Woodward; J. W. Evans; R. C. DeGroot

2000-01-01

The increased interest in copper-based wood preservatives has hastened the need for understanding why some fungi are able to attack copper-treated wood. Due in part to accumulation of oxalic acid by brown-rot fungi and visualization of copper oxalate crystals in wood decayed by known copper-tolerant decay fungi, oxalic acid has been implicated in copper tolerance by...

Isolation and characterization of new strains of methanogens from cold terrestrial habitats.

PubMed

Simankova, Maria V; Kotsyurbenko, Oleg R; Lueders, Tillmann; Nozhevnikova, Alla N; Wagner, Bianca; Conrad, Ralf; Friedrich, Michael W

2003-06-01

Five strains of methanogenic archaea (MT, MS, MM, MSP, ZB) were isolated from permanently and periodically cold terrestrial habitats. Physiological and morphological studies, as well as phylogenetic analyses of the new isolates were performed. Based on sequences of the 16S rRNA and methyl-coenzyme M reductase a-subunit (mcrA) genes all new isolates are closely related to known mesophilic and psychrotolerant methanogens. Both, phylogenetic analyses and phenotypic properties allow to classify strains MT, MS, and MM as members of the genus Methanosarcina. Strain MT is a new ecotype of Methanosarcina mazei, whereas strains MM and MS are very similar to each other and can be assigned to the recently described psychrotolerant species Methanosarcina lacustris. The hydrogenotrophic strain MSP is a new ecotype of the genus Methanocorpusculum. The obligately methylotrophic strain ZB is closely related to Methanomethylovorans hollandica and can be classified as new ecotype of this species. All new isolates, including the strains from permanently cold environments, are not true psychrophiles according to their growth temperature characteristics. In spite of the ability of all isolates to grow at temperatures as low as 1-5 degrees C, all of them have their growth optima in the range of moderate temperatures (25-35 degrees C). Thus, they can be regarded as psychrotolerant organisms. Psychrotolerant methanogens are thought to play an important role in methane production in both, habitats under seasonal temperature variations or from permanently cold areas.

[Lipid synthesis by an acidic acid tolerant Rhodotorula glutinis].

PubMed

Lin, Zhangnan; Liu, Hongjuan; Zhang, Jian'an; Wang, Gehua

2016-03-01

Acetic acid, as a main by-product generated in the pretreatment process of lignocellulose hydrolysis, significantly affects cell growth and lipid synthesis of oleaginous microorganisms. Therefore, we studied the tolerance of Rhodotorula glutinis to acetic acid and its lipid synthesis from substrate containing acetic acid. In the mixed sugar medium containing 6 g/L glucose and 44 g/L xylose, and supplemented with acetic acid, the cell growth was not:inhibited when the acetic acid concentration was below 10 g/L. Compared with the control, the biomass, lipid concentration and lipid content of R. glutinis increased 21.5%, 171% and 122% respectively when acetic acid concentration was 10 g/L. Furthermore, R. glutinis could accumulate lipid with acetate as the sole carbon source. Lipid concentration and lipid yield reached 3.20 g/L and 13% respectively with the initial acetic acid concentration of 25 g/L. The lipid composition was analyzed by gas chromatograph. The main composition of lipid produced with acetic acid was palmitic acid, stearic acid, oleic acid, linoleic acid and linolenic acid, including 40.9% saturated fatty acids and 59.1% unsaturated fatty acids. The lipid composition was similar to that of plant oil, indicating that lipid from oleaginous yeast R. glutinis had potential as the feedstock of biodiesel production. These results demonstrated that a certain concentration of acetic acid need not to be removed in the detoxification process when using lignocelluloses hydrolysate to produce microbial lipid by R. glutinis.

Open-label evaluation of a novel skin brightening system containing 0.01% decapeptide-12 in combination with 20% buffered glycolic acid for the treatment of mild to moderate facial melasma.

PubMed

Ramírez, Sandra P; Carvajal, Alfonso C; Salazar, Juan C; Arroyave, Gladys; Flórez, Ana M; Echeverry, Hector F

2013-06-01

Melasma is a cutaneous disorder that primarily affects females of Hispanic and Asian descent. Previous studies have shown that use of a brightening system comprised of 0.01% decapeptide-12 cream, an antioxidant cleanser, a 20% buffered glycolic acid lotion, and a broad spectrum SPF 30 sunscreen yields good clearance of mild-to-moderate melasma in Caucasian and Asian volunteers. The present open-label, prospective, and multicenter study sought to determine the tolerability and efficacy of the above-mentioned brightening system on mild-to-moderate melasma in 33 Hispanic females over 16 weeks. Clinical measures included self-assessment of tolerability, clinical grading, determination of Melasma Area and Severity Index (MASI) scores, and standardized clinical photography. Results showed that the system was well tolerated with no adverse events reported. Mean decreases of 36%, 46%, 54%, and 60% in MASI scores were observed at weeks 4, 8, 12, and 16, respectively, which were further corroborated by standardized photography showing visible reduction in the appearance of melasma. Results suggest that the brightening system consisting of 0.01% decapeptide-12 cream, an antioxidant cleanser, 20% buffered glycolic acid lotion, and broad spectrum SPF 30 sunscreen is safe and efficacious for the treatment of mild-to-moderate melasma in Hispanic females.

Identification of Methanogenic archaea in the Hyporheic Sediment of Sitka Stream

PubMed Central

Buriánková, Iva; Brablcová, Lenka; Mach, Václav; Dvořák, Petr; Chaudhary, Prem Prashant; Rulík, Martin

2013-01-01

Methanogenic archaea produce methane as a metabolic product under anoxic conditions and they play a crucial role in the global methane cycle. In this study molecular diversity of methanogenic archaea in the hyporheic sediment of the lowland stream Sitka (Olomouc, Czech Republic) was analyzed by PCR amplification, cloning and sequencing analysis of the methyl coenzyme M reductase alpha subunit (mcrA) gene. Sequencing analysis of 60 clones revealed 24 different mcrA phylotypes from hyporheic sedimentary layers to a depth of 50 cm. Phylotypes were affiliated with Methanomicrobiales, Methanosarcinales and Methanobacteriales orders. Only one phylotype remains unclassified. The majority of the phylotypes showed higher affiliation with uncultured methanogens than with known methanogenic species. The presence of relatively rich assemblage of methanogenic archaea confirmed that methanogens may be an important component of hyporheic microbial communities and may affect CH4 cycling in rivers. PMID:24278322

Diversity of methanogenic archaea in freshwater sediments of lacustrine ecosystems.

PubMed

Laskar, Folguni; Das Purkayastha, Sumi; Sen, Aniruddha; Bhattacharya, Mrinal K; Misra, Biswapriya B

2018-02-01

About half of the global methane (CH 4 ) emission is contributed by the methanogenic archaeal communities leading to a significant increase in global warming. This unprecedented situation has increased the ever growing necessity of evaluating the control measures for limiting CH 4 emission to the atmosphere. Unfortunately, research endeavors on the diversity and functional interactions of methanogens are not extensive till date. We anticipate that the study of the diversity of methanogenic community is paramount for understanding the metabolic processes in freshwater lake ecosystems. Although there are several disadvantages of conventional culture-based methods for determining the diversity of methanogenic archaeal communities, in order to understand their ecological roles in natural environments it is required to culture the microbes. Recently different molecular techniques have been developed for determining the structure of methanogenic archaeal communities thriving in freshwater lake ecosystem. The two gene based cloning techniques required for this purpose are 16S rRNA and methyl coenzyme M reductase (mcrA) in addition to the recently developed metagenomics approaches and high throughput next generation sequencing efforts. This review discusses the various methods of culture-dependent and -independent measures of determining the diversity of methanogen communities in lake sediments in lieu of the different molecular approaches and inter-relationships of diversity of methanogenic archaea. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Microbial diversity and methanogenic activity of Antrim Shale formation waters from recently fractured wells

PubMed Central

Wuchter, Cornelia; Banning, Erin; Mincer, Tracy J.; Drenzek, Nicholas J.; Coolen, Marco J. L.

2013-01-01

The Antrim Shale in the Michigan Basin is one of the most productive shale gas formations in the U.S., but optimal resource recovery strategies must rely on a thorough understanding of the complex biogeochemical, microbial, and physical interdependencies in this and similar systems. We used Illumina MiSeq 16S rDNA sequencing to analyze the diversity and relative abundance of prokaryotic communities present in Antrim shale formation water of three closely spaced recently fractured gas-producing wells. In addition, the well waters were incubated with a suite of fermentative and methanogenic substrates in an effort to stimulate microbial methane generation. The three wells exhibited substantial differences in their community structure that may arise from their different drilling and fracturing histories. Bacterial sequences greatly outnumbered those of archaea and shared highest similarity to previously described cultures of mesophiles and moderate halophiles within the Firmicutes, Bacteroidetes, and δ- and ε-Proteobacteria. The majority of archaeal sequences shared highest sequence similarity to uncultured euryarchaeotal environmental clones. Some sequences closely related to cultured methylotrophic and hydrogenotrophic methanogens were also present in the initial well water. Incubation with methanol and trimethylamine stimulated methylotrophic methanogens and resulted in the largest increase in methane production in the formation waters, while fermentation triggered by the addition of yeast extract and formate indirectly stimulated hydrogenotrophic methanogens. The addition of sterile powdered shale as a complex natural substrate stimulated the rate of methane production without affecting total methane yields. Depletion of methane indicative of anaerobic methane oxidation (AMO) was observed over the course of incubation with some substrates. This process could constitute a substantial loss of methane in the shale formation. PMID:24367357

Improving the cyanide toxicity tolerance of anaerobic reactor: Microbial interactions and toxin reduction.

PubMed

Gupta, Pragya; Ahammad, S Z; Sreekrishnan, T R

2016-09-05

Anaerobic biological treatment of high organics containing wastewater is amongst the preferred treatment options but poor tolerance to toxins makes its use prohibitive. In this study, efforts have been made to understand the key parameters for developing anaerobic reactor, resilient to cyanide toxicity. A laboratory scale anaerobic batch reactor was set up to treat cyanide containing wastewater. The reactor was inoculated with anaerobic sludge obtained from a wastewater treatment plant and fresh cow dung in the ratio of 3:1. The focus was on acclimatization and development of cyanide-degrading biomass and to understand the toxic effects of cyanide on the dynamic equilibrium between various microbial groups. The sludge exposed to cyanide was found to have higher bacterial diversity than the control. It was observed that certain hydrogenotrophic methanogens and bacterial groups were able to grow and produce methane in the presence of cyanide. Also, it was found that hydrogen utilizing methanogens were more cyanide tolerant than acetate utilizing methanogens. So, effluents from various industries like electroplating, coke oven plant, petroleum refining, explosive manufacturing, and pesticides industries which are having high concentrations of cyanide can be treated by favoring the growth of the tolerant microbes in the reactors. It will provide much better treatment efficiency by overcoming the inhibitory effects of cyanide to certain extent. Copyright © 2016 Elsevier B.V. All rights reserved.

The moderating and mediating roles of self-acceptance and tolerance to others in the relationship between mindfulness and subjective well-being.

PubMed

Xu, Wei; Oei, Tian Ps; Liu, Xinghua; Wang, Xiaoming; Ding, Chen

2016-07-01

This study explored the moderating and mediating influences of self-acceptance and tolerance to others in the relationship between mindfulness and subjective well-being. In total, 301 (130 males) university students completed the Five-Facet Mindfulness Questionnaire, Index of Well-being, Self-acceptance Questionnaire, and Tolerance Scale. The results showed that the positive link between mindfulness and subjective well-being was significantly mediated by self-acceptance only. Tolerance played a moderating role. The implications of the results for relevant research and mindfulness training were discussed. © The Author(s) 2014.

Low-pH production of D-lactic acid using newly isolated acid tolerant yeast Pichia kudriavzevii NG7.

PubMed

Park, Hyun Joo; Bae, Jung-Hoon; Ko, Hyeok-Jin; Lee, Sun-Hee; Sung, Bong Hyun; Han, Jong-In; Sohn, Jung-Hoon

2018-06-13

Lactic acid is a platform chemical for the sustainable production of various materials. To develop a robust yeast platform for low-pH production of D-lactic acid, an acid-tolerant yeast strain was isolated from grape skins and named Pichia kudriavzevii NG7 by ribosomal RNA sequencing. This strain was able to grow at pH 2.0 and 50°C. For the commercial application of P. kudriavzevii NG7 as a lactic acid producer, the ethanol fermentation pathway was redirected to lactic acid by replacing pyruvate decarboxylase 1 gene (PDC1) with D-lactate dehydrogenase gene (D-LDH) derived from Lactobacillus plantarum. To enhance lactic acid tolerance, this engineered strain was adapted to high lactic acid concentrations, and a new transcriptional regulator, PAR1, responsible for acid tolerance, was identified by whole-genome resequencing. The final engineered strain produced 135 g/L and 154 g/L of D-lactic acid with productivity over 3.66 g/L/h at pH 3.6 and 4.16 g/L/h at pH 4.7, respectively. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Effect of acid adaptation on the environmental stress tolerance of three strains of Vibrio parahaemolyticus.

PubMed

Chiang, Ming-Lun; Chen, Hsi-Chia; Wu, Chieh; Chen, Ming-Ju

2014-04-01

Three strains of Vibrio parahaemolyticus (690, BCRC 13023, and BCRC 13025), involved in foodborne outbreaks in Taiwan, were subjected to acid adaptation at pH 5.5 for 90 min. The effects of acid adaptation on the tolerance of V. parahaemolyticus to various environmental stresses, including heat (47°C), cold (4°C and -20°C), ethanol (8%), high salt (20% NaCl), and hydrogen peroxide (20 ppm) were examined. Results showed that acid adaptation increased the thermal tolerance of the three test strains of V. parahaemolyticus, while it did not affect their cold tolerance. Acid adaptation also increased the ethanol tolerance in V. parahaemolyticus 690 and BCRC 13025, but not in BCRC 13023. Differences in the tolerance to high salts were noted among the three strains after prior acid adaptation. However, these acid-adapted V. parahaemolyticus strains were more susceptible to hydrogen peroxide than their nonadapted controls. These findings demonstrated that acid adaption responses of V. parahaemolyticus varied among strains and types of stress challenge.

Screening of Non- Saccharomyces cerevisiae Strains for Tolerance to Formic Acid in Bioethanol Fermentation.

PubMed

Oshoma, Cyprian E; Greetham, Darren; Louis, Edward J; Smart, Katherine A; Phister, Trevor G; Powell, Chris; Du, Chenyu

2015-01-01

Formic acid is one of the major inhibitory compounds present in hydrolysates derived from lignocellulosic materials, the presence of which can significantly hamper the efficiency of converting available sugars into bioethanol. This study investigated the potential for screening formic acid tolerance in non-Saccharomyces cerevisiae yeast strains, which could be used for the development of advanced generation bioethanol processes. Spot plate and phenotypic microarray methods were used to screen the formic acid tolerance of 7 non-Saccharomyces cerevisiae yeasts. S. kudriavzeii IFO1802 and S. arboricolus 2.3319 displayed a higher formic acid tolerance when compared to other strains in the study. Strain S. arboricolus 2.3319 was selected for further investigation due to its genetic variability among the Saccharomyces species as related to Saccharomyces cerevisiae and availability of two sibling strains: S. arboricolus 2.3317 and 2.3318 in the lab. The tolerance of S. arboricolus strains (2.3317, 2.3318 and 2.3319) to formic acid was further investigated by lab-scale fermentation analysis, and compared with S. cerevisiae NCYC2592. S. arboricolus 2.3319 demonstrated improved formic acid tolerance and a similar bioethanol synthesis capacity to S. cerevisiae NCYC2592, while S. arboricolus 2.3317 and 2.3318 exhibited an overall inferior performance. Metabolite analysis indicated that S. arboricolus strain 2.3319 accumulated comparatively high concentrations of glycerol and glycogen, which may have contributed to its ability to tolerate high levels of formic acid.

Screening of Non- Saccharomyces cerevisiae Strains for Tolerance to Formic Acid in Bioethanol Fermentation

PubMed Central

Oshoma, Cyprian E.; Greetham, Darren; Louis, Edward J.; Smart, Katherine A.; Phister, Trevor G.; Powell, Chris; Du, Chenyu

2015-01-01

Formic acid is one of the major inhibitory compounds present in hydrolysates derived from lignocellulosic materials, the presence of which can significantly hamper the efficiency of converting available sugars into bioethanol. This study investigated the potential for screening formic acid tolerance in non-Saccharomyces cerevisiae yeast strains, which could be used for the development of advanced generation bioethanol processes. Spot plate and phenotypic microarray methods were used to screen the formic acid tolerance of 7 non-Saccharomyces cerevisiae yeasts. S. kudriavzeii IFO1802 and S. arboricolus 2.3319 displayed a higher formic acid tolerance when compared to other strains in the study. Strain S. arboricolus 2.3319 was selected for further investigation due to its genetic variability among the Saccharomyces species as related to Saccharomyces cerevisiae and availability of two sibling strains: S. arboricolus 2.3317 and 2.3318 in the lab. The tolerance of S. arboricolus strains (2.3317, 2.3318 and 2.3319) to formic acid was further investigated by lab-scale fermentation analysis, and compared with S. cerevisiae NCYC2592. S. arboricolus 2.3319 demonstrated improved formic acid tolerance and a similar bioethanol synthesis capacity to S. cerevisiae NCYC2592, while S. arboricolus 2.3317 and 2.3318 exhibited an overall inferior performance. Metabolite analysis indicated that S. arboricolus strain 2.3319 accumulated comparatively high concentrations of glycerol and glycogen, which may have contributed to its ability to tolerate high levels of formic acid. PMID:26284784

Tolerance of negative emotion moderates the amplification of mental contamination following an evoking task: A randomized experimental study.

PubMed

Fergus, Thomas A

2018-06-01

Contamination is a near universal feeling, with mental contamination representing a contamination feeling in the absence of direct physical contact with a source. Extant research indicates that tolerance of negative emotion is important for understanding emotional reactions to images, thoughts, and memories, all of which are common sources of mental contamination. Extending research linking distress tolerance to mental contamination, this study examined if individual differences in the tolerance of negative emotion moderates the amplification of mental contamination following an evoking task. Unselected participants completed a self-report measure of tolerance of negative emotion during an online session. They later attended an in-person session and were randomized to an experimental scenario group: betrayal (n = 49) or control (n = 49). Participants imagined themselves in a scenario, with the betrayal scenario designed to evoke mental contamination. Mental contamination was assessed by self-report before and after the scenario. The betrayal, but not control, scenario caused an increase in mental contamination. Tolerance for negative emotion moderated the effect of group on mental contamination. Group differences in mental contamination evidenced at low, but not high, distress tolerance. A novel experimental manipulation and an unselected sample were used. Future research could assess tolerance of negative emotion using a behavioral task. These results indicate that tolerance of negative emotion may be important for understanding when individuals experience mental contamination. Copyright © 2017 Elsevier Ltd. All rights reserved.

TOLERANCE TO AMINO ACID MIXTURES AND CASEIN DIGESTS GIVEN INTRAVENOUSLY

PubMed Central

Madden, S. C.; Woods, R. R.; Shull, F. W.; Remington, J. H.; Whipple, G. H.

1945-01-01

Several synthetic mixtures of natural and racemic crystalline amino acids suitable for the daily nitrogen requirement are tested in dogs for their tolerance upon intravenous injection. Certain mixtures of the ten essential amino acids plus non-essential amino acids exclusive of glutamic acid are accepted without any obvious sign of disturbance even at rates above 10 mg. nitrogen per kilo per minute for quantities greater than 300 mg. per kilo. One such mixture consists in parts per 100 of dl-threonine 7, dl-valine 15, l(-)-leucine 10.9, dl-isoleucine 9.9, l(+)-lysine· HCl·H2O 10.9, dl-tryptophane 3, dl-phenylalanine 9.9, dl-methionine 6, l(+)-histidine·HCl·H2O 5, l(+)-arginine-HCl 5, glycine 9.9, dl-α-alanine 4, dl-serine 2, l(-)-cystine 0.5, and l(-)-tyrosine 1. In addition other well tolerated mixtures included the prolines. When glutamic acid, natural or racemic, is included in similar mixtures vomiting reactions frequently occur at nitrogen rates above 4 mg. per kilo per minute. Vomiting almost always occurs on the first daily injection containing glutamic acid and usually on any subsequent injection containing more than 100 mg. glutamic acid per kilo unless given very slowly. Upon the addition of glycine certain mixtures of the ten essential amino acids show an improved tolerance. Two casein digests tested usually produced vomiting at injection rates above 2 mg. nitrogen per kilo per minute, probably because of their glutamic acid content. No serious reaction has ever occurrred to any mixture of amino acids or casein digest tested. Elimination of minor reactions such as vomiting appears possible and desirable for greater usefulness of these solutions in parenteral feeding. PMID:19871468

Spatial Variations of the Methanogenic Communities in the Sediments of Tropical Mangroves

PubMed Central

Jing, Hongmei; Cheung, Shunyan; Zhou, Zhi; Wu, Chen; Nagarajan, Sanjay; Liu, Hongbin

2016-01-01

Methane production by methanogens in mangrove sediments is known to contribute significantly to global warming, but studies on the shift of methanogenic community in response to anthropogenic contaminations were still limited. In this study, the effect of anthropogenic activities in the mangrove sediments along the north and south coastlines of Singapore were investigated by pyrosequencing of the mcrA gene. Our results showed that hydrogenotrophic, acetoclastic and methylotrophic methanogens coexist in the sediments. The predominance of the methylotrophic Methanosarcinales reflects the potential for high methane production as well as the possible availability of low acetate and high methylated C-1 compounds as substrates. A decline in the number of acetoclastic/methylotrophic methanogens in favor of hydrogenotrophic methanogens was observed along a vertical profile in Sungei Changi, which was contaminated by heavy metals. The diversity of methanogens in the various contaminated stations was significantly different from that in a pristine St. John’s Island. The spatial variation in the methanogenic communities among the different stations was more distinct than those along the vertical profiles at each station. We suggest that the overall heterogeneity of the methanogenic communities residing in the tropical mangrove sediments might be due to the accumulated effects of temperature and concentrations of nitrate, cobalt, and nickel. PMID:27684479

Methane Production and Methanogenic Archaea in the Digestive Tracts of Millipedes (Diplopoda)

PubMed Central

Šustr, Vladimír; Chroňáková, Alica; Semanová, Stanislava; Tajovský, Karel; Šimek, Miloslav

2014-01-01

Methane production by intestinal methanogenic Archaea and their community structure were compared among phylogenetic lineages of millipedes. Tropical and temperate millipedes of 35 species and 17 families were investigated. Species that emitted methane were mostly in the juliform orders Julida, Spirobolida, and Spirostreptida. The irregular phylogenetic distribution of methane production correlated with the presence of the methanogen-specific mcrA gene. The study brings the first detailed survey of methanogens’ diversity in the digestive tract of millipedes. Sequences related to Methanosarcinales, Methanobacteriales, Methanomicrobiales and some unclassified Archaea were detected using molecular profiling (DGGE). The differences in substrate preferences of the main lineages of methanogenic Archaea found in different millipede orders indicate that the composition of methanogen communities may reflect the differences in available substrates for methanogenesis or the presence of symbiotic protozoa in the digestive tract. We conclude that differences in methane production in the millipede gut reflect differences in the activity and proliferation of intestinal methanogens rather than an absolute inability of some millipede taxa to host methanogens. This inference was supported by the general presence of methanogenic activity in millipede faecal pellets and the presence of the 16S rRNA gene of methanogens in all tested taxa in the two main groups of millipedes, the Helminthophora and the Pentazonia. PMID:25028969

Methanogens in the Solar System

NASA Astrophysics Data System (ADS)

Taubner, Ruth-Sophie; Schleper, Christa; Firneis, Maria G.; Rittmann, Simon

2015-04-01

The last decade of space science revealed that potential habitats in the Solar System may not be limited to the classical habitable zone supporting life as we know it. These microorganisms were shown to thrive under extremophilic growth conditions. Here, we outline the main eco-physiological characteristics of methanogens like their response on temperature, pressure, or pH changes or their resistance against radiation or desiccation. They can withstand extreme environmental conditions which makes them intriguing organisms for astrobiological studies. On Earth, they are found for example in wetlands, in arctic and antarctic subglacial environments, in ruminants, and even in the environment surrounding the Mars Desert Research Station in Utah. These obligate anaerobic chemolithoautotrophs or chemolithoheterotrophs are able to use e.g. hydrogen and C1 compounds like CO2, formate, or methanol as energy source and carbon source, respectively. We point out their capability to be able to habitat potential extraterrestrial biospheres all over the planetary system. We will give an overview about these possible environments on Mars, icy moons like Europa or Enceladus, and minor planets. We present an overview about studies of methanogens with an astrobiological relevance and we show our conclusions about the role of methanogens for the search for extraterrestrial life in the Solar System. We will present first results of our study about the possibility to cultivate methanogens under Enceladus-like conditions. For that, based on the observations obtained by the Cassini spacecraft concerning the plume compounds, we produce a medium with a composition similar to the ocean composition of this icy moon which is far more Enceladus-like than in any (published) experiment before. Eventually, we give an outlook on the feasibility and the necessity of future astrobiological studies with these microbes. We point out the importance of future in-situ or even sample and return missions to

Effects of transgenic Bt rice on the active rhizospheric methanogenic archaeal community as revealed by DNA-based stable isotope probing.

PubMed

Han, Cheng; Liu, Biao; Zhong, Wenhui

2018-05-30

This study aimed to investigate the influence of planting Cry1Ab/Cry1Ac gene expressing rice (Bt rice) on rhizospheric active methanogenic archaeal communities. The non-transgenic parental line was used as the control (Ck rice). DNA-based stable isotope probing (DNA-SIP) technology traced the rhizospheric active methanogens at the tillering stage. The results revealed significantly lower CH 4 emission flux from Bt soil than that from Ck soil during the whole growth period. The active methanogenic community composition remained stable. The RC-I lineage (77.9-79.8%) and Methanosaetaceae (13.9-15.1%) were the predominant active methanogens in Bt and Ck rice rhizospheres. However, the abundance of functionally active methanogens in the Bt rice rhizosphere was significantly reduced. Lower levels of root exudates (that included carbohydrate and organic acids) from Bt rice were also detected at the tillering stage. This study found that the genetic modification of rice reduced the potential methanogenic substrates came from plant-derived root exudates, which represented an important factor in reducing CH 4 generation and active methanogenic archaeal abundance in Bt rhizosphere soil. The effect of genetically modified (GM) insect-resistant crops on soil microorganisms has become an issue of public concern, especially the indirect effect of plant metabolisms caused by the insertion of foreign genes. Methanogenesis, which is regarded as a critical ecological process in paddy soil, is influenced by plant root exudates; these are mainly derived from photosynthesis. The variations in root exudates across the Bt and Ck rice suggested the indirect influence of foreign gene insertion. DNA-SIP successfully traced the active methanogenic archaeal populations assimilating 13 C-labeled photosynthetic carbon and found a strong influence of planting Bt rice on active methanogens. As a consequence, we proposed that analysis of functionally active microorganisms is more suitable for

Field Evidence for Magnetite Formation by a Methanogenic Microbial Community

NASA Astrophysics Data System (ADS)

Rossbach, S.; Beaver, C. L.; Williams, A.; Atekwana, E. A.; Slater, L. D.; Ntarlagiannis, D.; Lund, A.

2015-12-01

The aged, subsurface petroleum spill in Bemidji, Minnesota, has been surveyed with magnetic susceptibility (MS) measurements. High MS values were found in the free-product phase around the fluctuating water table. Although we had hypothesized that high MS values are related to the occurrence of the mineral magnetite resulting from the activity of iron-reducing bacteria, our microbial analysis pointed to the presence of a methanogenic microbial community at the locations and depths of the highest MS values. Here, we report on a more detailed microbial analysis based on high-throughput sequencing of the 16S rRNA gene of sediment samples from four consecutive years. In addition, we provide geochemical data (FeII/FeIII concentrations) to refine our conceptual model of methanogenic hydrocarbon degradation at aged petroleum spills and demonstrate that the microbial induced changes of sediment properties can be monitored with MS. The methanogenic microbial community at the Bemidji site consisted mainly of the syntrophic, hydrocarbon-degrading Smithella and the hydrogenotrophic, methane-generating Methanoregula. There is growing evidence in the literature that not only Bacteria, but also some methanogenic Archaea are able to reduce iron. In fact, a recent study reported that the methanogen Methanosarcina thermophila produced magnetite during the reduction of ferrihydrite in a laboratory experiment when hydrogen was present. Therefore, our finding of high MS values and the presence of magnetite in the methanogenic zone of an aged, subsurface petroleum spill could very well be the first field evidence for magnetite formation during methanogenic hydrocarbon degradation.

Methane production from coal by a single methanogen

NASA Astrophysics Data System (ADS)

Sakata, S.; Mayumi, D.; Mochimaru, H.; Tamaki, H.; Yamamoto, K.; Yoshioka, H.; Suzuki, Y.; Kamagata, Y.

2017-12-01

Previous geochemical studies indicate that biogenic methane greatly contributes to the formation of coalbed methane (CBM). It is unclear, however, what part of coal is used for the methane production and what types of microbes mediate the process. Here we hypothesized that methylotrophic methanogens use methoxylated aromatic compounds (MACs) derived from lignin. We incubated 11 species of methanogens belonging to order Methanosarcinales with 7 types of MACs. Two strains of methanogens, i.e., Methermicoccus shengliensis AmaM and ZC-1, produced methane from the MACs. In fact, these methanogens used over 30 types of commercially available MACs in addition to methanol and methylamines. To date, it is widely believed that methanogens use very limited number of small compounds such as hydrogen plus carbon dioxide, acetate, and methanol, and only three methanogenic pathways are recognized accordingly. Here, in contrast, two Methermicoccus strains used many types of MACs. We therefore propose this "methoxydotrophic" process as the fourth methanogenic pathway. Incubation of AmaM with 2-methoxybenzoate resulted in methanogenesis associated with the stoichiometric production of 2-hydroxybenzoate. Incubation with 2-methoxy-[7-13C] benzoate and with [13C] bicarbonate indicated that two thirds of methane carbon derived from the methoxy group and one third from CO2. Furthermore, incubation with [2-13C] acetate resulted in significant increases of 13C in both methane and CO2. These results suggest the occurrence of O-demethylation, CO2 reduction and acetyl-CoA metabolism in the methoxydotrophic methanogenesis. Furthermore, incubation of AmaM with lignite, subbituminous or bituminous coals in the bicarbonate-buffered media revealed that AmaM produced methane directly from coals via the methoxydotrophic pathway. Although 4 types of MACs were detected in the coal media in addition to methanol and methylamines, their total concentrations were too low to account for the methane

Amino acids implicated in plant defense are higher in Candidatus Liberibacter asiaticus-tolerant citrus varieties

PubMed Central

Killiny, Nabil; Hijaz, Faraj

2016-01-01

ABSTRACT Citrus Huanglongbing (HLB), also known as citrus greening, has been threatening the citrus industry since the early 1900's and up to this date there are no effective cures for this disease. Field observations and greenhouse controlled studies demonstrated that some citrus genotypes are more tolerant to Candidatus Liberibacter asiaticus (CLas) pathogen than others. However, the mechanisms underpinning tolerance has not been determined yet. The phloem sap composition of CLas-tolerant and sensitive citrus varieties was studied to identify metabolites that could be responsible for their tolerance to CLas. The citrus phloem sap was collected by centrifugation and was analyzed with gas chromatography-mass spectrometry after methyl chloroformate derivatization. Thirty-three metabolites were detected in the phloem sap of the studied varieties: twenty 20 amino acids, eight 8 organic acids, and five 5 fatty acids. Interestingly, the levels of most amino acids, especially those implicated in plantdefense to pathogens such as phenylalanine, tyrosine, tryptophan, lysine, and asparagine were higher in tolerant varieties. Although the level of organic acids varied between cultivars, this variation was not correlated with citrus resistance to CLas and could be cultivar specific. The fatty acids were found in trace amounts and in most cases their levels were not significantly different among varieties. Better understanding of the mechanisms underpinning citrus tolerance to CLas will help in developing economically tolerant varieties. PMID:27057814

Amino acids implicated in plant defense are higher in Candidatus Liberibacter asiaticus-tolerant citrus varieties.

PubMed

Killiny, Nabil; Hijaz, Faraj

2016-01-01

Citrus Huanglongbing (HLB), also known as citrus greening, has been threatening the citrus industry since the early 1900's and up to this date there are no effective cures for this disease. Field observations and greenhouse controlled studies demonstrated that some citrus genotypes are more tolerant to Candidatus Liberibacter asiaticus (CLas) pathogen than others. However, the mechanisms underpinning tolerance has not been determined yet. The phloem sap composition of CLas-tolerant and sensitive citrus varieties was studied to identify metabolites that could be responsible for their tolerance to CLas. The citrus phloem sap was collected by centrifugation and was analyzed with gas chromatography-mass spectrometry after methyl chloroformate derivatization. Thirty-three metabolites were detected in the phloem sap of the studied varieties: twenty 20 amino acids, eight 8 organic acids, and five 5 fatty acids. Interestingly, the levels of most amino acids, especially those implicated in plantdefense to pathogens such as phenylalanine, tyrosine, tryptophan, lysine, and asparagine were higher in tolerant varieties. Although the level of organic acids varied between cultivars, this variation was not correlated with citrus resistance to CLas and could be cultivar specific. The fatty acids were found in trace amounts and in most cases their levels were not significantly different among varieties. Better understanding of the mechanisms underpinning citrus tolerance to CLas will help in developing economically tolerant varieties.

40 CFR 180.1210 - Phosphorous acid; exemption from the requirement of a tolerance.

Code of Federal Regulations, 2011 CFR

2011-07-01

... AGENCY (CONTINUED) PESTICIDE PROGRAMS TOLERANCES AND EXEMPTIONS FOR PESTICIDE CHEMICAL RESIDUES IN FOOD... exemption from the requirement of a tolerance is established for residues of phosphorous acid and its... and in or on potatoes when applied as a post-harvest treatment at 35,600 ppm or less phosphorous acid...

40 CFR 180.1210 - Phosphorous acid; exemption from the requirement of a tolerance.

Code of Federal Regulations, 2010 CFR

2010-07-01

... AGENCY (CONTINUED) PESTICIDE PROGRAMS TOLERANCES AND EXEMPTIONS FOR PESTICIDE CHEMICAL RESIDUES IN FOOD... exemption from the requirement of a tolerance is established for residues of phosphorous acid and its... and in or on potatoes when applied as a post-harvest treatment at 35,600 ppm or less phosphorous acid...

40 CFR 180.1225 - Decanoic acid; exemption from the requirement of a tolerance.

Code of Federal Regulations, 2011 CFR

2011-07-01

... AGENCY (CONTINUED) PESTICIDE PROGRAMS TOLERANCES AND EXEMPTIONS FOR PESTICIDE CHEMICAL RESIDUES IN FOOD... exemption from the requirement of a tolerance is established for residues of decanoic acid in or on all raw... acid (up to 170 ppm per application) on food contact surfaces such as equipment, pipelines, tanks, vats...

Studying gene regulation in methanogenic archaea.

PubMed

Rother, Michael; Sattler, Christian; Stock, Tilmann

2011-01-01

Methanogenic archaea are a unique group of strictly anaerobic microorganisms characterized by their ability, and dependence, to convert simple C1 and C2 compounds to methane for growth. The major models for studying the biology of methanogens are members of the Methanococcus and Methanosarcina species. Recent development of sophisticated tools for molecular analysis and for genetic manipulation allows investigating not only their metabolism but also their cell cycle, and their interaction with the environment in great detail. One aspect of such analyses is assessment and dissection of methanoarchaeal gene regulation, for which, at present, only a handful of cases have been investigated thoroughly, partly due to the great methodological effort required. However, it becomes more and more evident that many new regulatory paradigms can be unraveled in this unique archaeal group. Here, we report both molecular and physiological/genetic methods to assess gene regulation in Methanococcus maripaludis and Methanosarcina acetivorans, which should, however, be applicable for other methanogens as well. Copyright © 2011 Elsevier Inc. All rights reserved.

Anaerobic Degradation of Phthalate Isomers by Methanogenic Consortia

PubMed Central

Kleerebezem, Robbert; Pol, Look W. Hulshoff; Lettinga, Gatze

1999-01-01

Three methanogenic enrichment cultures, grown on ortho-phthalate, iso-phthalate, or terephthalate were obtained from digested sewage sludge or methanogenic granular sludge. Cultures grown on one of the phthalate isomers were not capable of degrading the other phthalate isomers. All three cultures had the ability to degrade benzoate. Maximum specific growth rates (μSmax) and biomass yields (YXtotS) of the mixed cultures were determined by using both the phthalate isomers and benzoate as substrates. Comparable values for these parameters were found for all three cultures. Values for μSmax and YXtotS were higher for growth on benzoate compared to the phthalate isomers. Based on measured and estimated values for the microbial yield of the methanogens in the mixed culture, specific yields for the phthalate and benzoate fermenting organisms were calculated. A kinetic model, involving three microbial species, was developed to predict intermediate acetate and hydrogen accumulation and the final production of methane. Values for the ratio of the concentrations of methanogenic organisms, versus the phthalate isomer and benzoate fermenting organisms, and apparent half-saturation constants (KS) for the methanogens were calculated. By using this combination of measured and estimated parameter values, a reasonable description of intermediate accumulation and methane formation was obtained, with the initial concentration of phthalate fermenting organisms being the only variable. The energetic efficiency for growth of the fermenting organisms on the phthalate isomers was calculated to be significantly smaller than for growth on benzoate. PMID:10049876

77 FR 21676 - Silicic Acid, Sodium Salt etc.; Tolerance Exemption

Federal Register 2010, 2011, 2012, 2013, 2014

2012-04-11

... Silicic acid, sodium salt, reaction products with chlorotrimethylsilane and iso-propyl alcohol, reaction..., reaction products with chlorotrimethylsilane and iso-propyl alcohol, reaction with poly(oxypropylene)-poly... from the requirement of a tolerance for residues of Silicic acid, sodium salt, reaction products with...

Archaea and Bacteria Acclimate to High Total Ammonia in a Methanogenic Reactor Treating Swine Waste

PubMed Central

Parameswaran, Prathap; Rittmann, Bruce E.

2016-01-01

Inhibition by ammonium at concentrations above 1000 mgN/L is known to harm the methanogenesis phase of anaerobic digestion. We anaerobically digested swine waste and achieved steady state COD-removal efficiency of around 52% with no fatty-acid or H2 accumulation. As the anaerobic microbial community adapted to the gradual increase of total ammonia-N (NH3-N) from 890 ± 295 to 2040 ± 30 mg/L, the Bacterial and Archaeal communities became less diverse. Phylotypes most closely related to hydrogenotrophic Methanoculleus (36.4%) and Methanobrevibacter (11.6%), along with acetoclastic Methanosaeta (29.3%), became the most abundant Archaeal sequences during acclimation. This was accompanied by a sharp increase in the relative abundances of phylotypes most closely related to acetogens and fatty-acid producers (Clostridium, Coprococcus, and Sphaerochaeta) and syntrophic fatty-acid Bacteria (Syntrophomonas, Clostridium, Clostridiaceae species, and Cloacamonaceae species) that have metabolic capabilities for butyrate and propionate fermentation, as well as for reverse acetogenesis. Our results provide evidence countering a prevailing theory that acetoclastic methanogens are selectively inhibited when the total ammonia-N concentration is greater than ~1000 mgN/L. Instead, acetoclastic and hydrogenotrophic methanogens coexisted in the presence of total ammonia-N of ~2000 mgN/L by establishing syntrophic relationships with fatty-acid fermenters, as well as homoacetogens able to carry out forward and reverse acetogenesis. PMID:27725793

Archaea and Bacteria Acclimate to High Total Ammonia in a Methanogenic Reactor Treating Swine Waste.

PubMed

Esquivel-Elizondo, Sofia; Parameswaran, Prathap; Delgado, Anca G; Maldonado, Juan; Rittmann, Bruce E; Krajmalnik-Brown, Rosa

2016-01-01

Inhibition by ammonium at concentrations above 1000 mgN/L is known to harm the methanogenesis phase of anaerobic digestion. We anaerobically digested swine waste and achieved steady state COD-removal efficiency of around 52% with no fatty-acid or H 2 accumulation. As the anaerobic microbial community adapted to the gradual increase of total ammonia-N (NH 3 -N) from 890 ± 295 to 2040 ± 30 mg/L, the Bacterial and Archaeal communities became less diverse. Phylotypes most closely related to hydrogenotrophic Methanoculleus (36.4%) and Methanobrevibacter (11.6%), along with acetoclastic Methanosaeta (29.3%), became the most abundant Archaeal sequences during acclimation. This was accompanied by a sharp increase in the relative abundances of phylotypes most closely related to acetogens and fatty-acid producers ( Clostridium , Coprococcus , and Sphaerochaeta ) and syntrophic fatty-acid Bacteria ( Syntrophomonas , Clostridium , Clostridiaceae species, and Cloacamonaceae species) that have metabolic capabilities for butyrate and propionate fermentation, as well as for reverse acetogenesis. Our results provide evidence countering a prevailing theory that acetoclastic methanogens are selectively inhibited when the total ammonia-N concentration is greater than ~1000 mgN/L. Instead, acetoclastic and hydrogenotrophic methanogens coexisted in the presence of total ammonia-N of ~2000 mgN/L by establishing syntrophic relationships with fatty-acid fermenters, as well as homoacetogens able to carry out forward and reverse acetogenesis.

Global Biogeographic Analysis of Methanogenic Archaea Identifies Community-Shaping Environmental Factors of Natural Environments

PubMed Central

Wen, Xi; Yang, Sizhong; Horn, Fabian; Winkel, Matthias; Wagner, Dirk; Liebner, Susanne

2017-01-01

Methanogenic archaea are important for the global greenhouse gas budget since they produce methane under anoxic conditions in numerous natural environments such as oceans, estuaries, soils, and lakes. Whether and how environmental change will propagate into methanogenic assemblages of natural environments remains largely unknown owing to a poor understanding of global distribution patterns and environmental drivers of this specific group of microorganisms. In this study, we performed a meta-analysis targeting the biogeographic patterns and environmental controls of methanogenic communities using 94 public mcrA gene datasets. We show a global pattern of methanogenic archaea that is more associated with habitat filtering than with geographical dispersal. We identify salinity as the control on methanogenic community composition at global scale whereas pH and temperature are the major controls in non-saline soils and lakes. The importance of salinity for structuring methanogenic community composition is also reflected in the biogeography of methanogenic lineages and the physiological properties of methanogenic isolates. Linking methanogenic alpha-diversity with reported values of methane emission identifies estuaries as the most diverse methanogenic habitats with, however, minor contribution to the global methane budget. With salinity, temperature and pH our study identifies environmental drivers of methanogenic community composition facing drastic changes in many natural environments at the moment. However, consequences of this for the production of methane remain elusive owing to a lack of studies that combine methane production rate with community analysis. PMID:28769904

A hydrogen-based subsurface microbial community dominated by methanogens

USGS Publications Warehouse

Chapelle, F.H.; O'Neil, Kyle; Bradley, P.M.; Methe, B.A.; Ciufo, S.A.; Knobel, L.L.; Lovley, D.R.

2002-01-01

The search for extraterrestrial life may be facilitated if ecosystems can be found on Earth that exist under conditions analogous to those present on other planets or moons. It has been proposed, on the basis of geochemical and thermodynamic considerations, that geologically derived hydrogen might support subsurface microbial communities on Mars and Europa in which methanogens form the base of the ecosystem1-5. Here we describe a unique subsurface microbial community in which hydrogen-consuming, methane-producing Archaea far outnumber the Bacteria. More than 90% of the 16s ribosomal DNA sequences recovered from hydrothermal waters circulating through deeply buried igneous rocks in Idaho are related to hydrogen-using methanogenic microorganisms. Geochemical characterization indicates that geothermal hydrogen, not organic carbon, is the primary energy source for this methanogen-dominated microbial community. These results demonstrate that hydrogen-based methanogenic communities do occur in Earth's subsurface, providing an analogue for possible subsurface microbial ecosystems on other planets.

Evaluation of the efficacy, tolerability, and safety of an over-the-counter acne regimen containing benzoyl peroxide and salicylic acid in subjects with acne.

PubMed

Kircik, Leon H; Gwazdauskas, Jennifer; Butners, Victoria; Eastern, Joseph; Green, Lawrence J

2013-03-01

Benzoyl peroxide (BPO) is a widely used over-the-counter (OTC) topical acne treatment often used in combination with salicylic acid (SA) to achieve better comedone control than that achieved with BPO alone. MaxClarity™ is an OTC acne treatment system comprising BPO and SA in an aqueous foam delivery vehicle, VersaFoam AF™. This paper describes 2 open-label, single-arm studies conducted to assess the efficacy, safety, tolerability, and patient preference of MaxClarity in the treatment of mild, moderate, and severe acne. Subjects applied MaxClarity twice daily for 8 weeks in study 402 and for 12 weeks in study 405. Reductions in all lesion types were seen throughout both studies. At week 8 (study 402), there was a mean reduction from baseline of -56.9 ± 32.7% in total lesions in subjects with mild, moderate, or severe acne. At week 12 (study 405), there was a reduction from baseline of -61.6 ± 22.0% in total lesions in subjects with moderate or severe acne. Overall, both studies demonstrated that MaxClarity is a generally well tolerated and effective treatment for mild, moderate, and severe acne.

75 FR 31713 - 2-Propenoic acid polymer, with 1,3-butadiene and ethenylbenzene; Tolerance Exemption

Federal Register 2010, 2011, 2012, 2013, 2014

2010-06-04

... acid polymer, with 1,3-butadiene and ethenylbenzene; Tolerance Exemption AGENCY: Environmental... requirement of a tolerance for residues of 2-propenoic acid polymer, with 1,3- butadiene and ethenylbenzene... residues of 2-propenoic acid polymer, with 1,3-butadiene and ethenylbenzene on food or feed commodities...

Genome-wide identification of Saccharomyces cerevisiae genes required for tolerance to acetic acid.

PubMed

Mira, Nuno P; Palma, Margarida; Guerreiro, Joana F; Sá-Correia, Isabel

2010-10-25

Acetic acid is a byproduct of Saccharomyces cerevisiae alcoholic fermentation. Together with high concentrations of ethanol and other toxic metabolites, acetic acid may contribute to fermentation arrest and reduced ethanol productivity. This weak acid is also a present in lignocellulosic hydrolysates, a highly interesting non-feedstock substrate in industrial biotechnology. Therefore, the better understanding of the molecular mechanisms underlying S. cerevisiae tolerance to acetic acid is essential for the rational selection of optimal fermentation conditions and the engineering of more robust industrial strains to be used in processes in which yeast is explored as cell factory. The yeast genes conferring protection against acetic acid were identified in this study at a genome-wide scale, based on the screening of the EUROSCARF haploid mutant collection for susceptibility phenotypes to this weak acid (concentrations in the range 70-110 mM, at pH 4.5). Approximately 650 determinants of tolerance to acetic acid were identified. Clustering of these acetic acid-resistance genes based on their biological function indicated an enrichment of genes involved in transcription, internal pH homeostasis, carbohydrate metabolism, cell wall assembly, biogenesis of mitochondria, ribosome and vacuole, and in the sensing, signalling and uptake of various nutrients in particular iron, potassium, glucose and amino acids. A correlation between increased resistance to acetic acid and the level of potassium in the growth medium was found. The activation of the Snf1p signalling pathway, involved in yeast response to glucose starvation, is demonstrated to occur in response to acetic acid stress but no evidence was obtained supporting the acetic acid-induced inhibition of glucose uptake. Approximately 490 of the 650 determinants of tolerance to acetic acid identified in this work are implicated, for the first time, in tolerance to this weak acid. These are novel candidate genes for genetic

Comparison of salicylic acid 30% peel and pneumatic broadband light in the treatment of mild to moderately severe facial acne vulgaris.

PubMed

Thuangtong, Rattapon; Tangjaturonrusamee, Chinmanat; Rattanaumpawan, Pinyo; Ditre, Chérie M

2017-07-01

Acne patients experience not only a medical disease but also an aesthetic condition, and this latter complication greatly motivates patients to seek out the best treatment regimen to hasten improvement in their appearance. The available clinical procedures for acne treatment include salicylic acid 30% peel and pneumatic broadband light (PBBL). The objective of this study was to compare the efficacy of salicylic acid 30% peel and PBBL treatments in patients with mild to moderately severe facial acne vulgaris. Twelve patients were recruited for a 12-week prospective, single-blind, randomized, split-face study. Patients were treated with a salicylic acid 30% peel on one side of the face and PBBL treatment was administered on the opposite side of the face for 6 consecutive weeks without other acne treatments. At every visit, treatment evaluations were performed using a modified Global Acne Grading Score (mGAGS), acne quality of life (QOL) questionnaire, Wong-Baker FACES Pain Rating Scale (WBPRS) assessments, and clinical photography. Improvement in acne symptoms was observed for both treatment procedures without significant differences and with minimal side effects. Salicylic acid 30% peel and PBBL were well tolerated in our study, and both clinical procedures were efficacious and well-tolerated by the patients.

A new methanogen "Methanobrevibacter massiliense" isolated in a case of severe periodontitis.

PubMed

Huynh, Hong T T; Pignoly, Marion; Drancourt, Michel; Aboudharam, Gérard

2017-12-01

A few methanogens have been previously recovered from periodontitis lesions, yet their repertoire may not be completed. We recovered a previously unreported methanogen species in this situation. A 64-year-old Caucasian woman was diagnosed with chronic, severe generalized periodontitis. In the presence of negative controls, an 18-month culture of periodontal pockets in anaerobe Hungate tube yielded "Methanobrevibacter massiliense" and Pyramidobacter piscolens. This case report provides evidence of the symbiotic strategy deployed by the methanogens and the anaerobes, and reports the first culture of a new methanogen, "M. massiliense".

Isolation, identification and fibrolytic characteristics of rumen fungi grown with indigenous methanogen from yaks (Bos grunniens) grazing on the Qinghai-Tibetan Plateau.

PubMed

Wei, Y-Q; Yang, H-J; Luan, Y; Long, R-J; Wu, Y-J; Wang, Z-Y

2016-03-01

To obtain co-cultures of anaerobic fungi and their indigenously associated methanogens from the rumen of yaks grazing on the Qinghai-Tibetan Plateau and investigate their morphology features and ability to degrade lignocellulose. Twenty fungus-methanogen co-cultures were obtained by Hungate roll-tube technique. The fungi were identified as Orpinomyces, Neocallimastix and Piromyces genera based on the morphological characteristics and internal transcribed spacer 1 sequences analysis. All methanogens were identified as Methanobrevibacter sp. by 16S rRNA gene sequencing. There were four types of co-cultures: Neocallimastix with Methanobrevibacter ruminantium, Orpinomyces with M. ruminantium, Orpinomyces with Methanobrevibacter millerae and Piromyces with M. ruminantium among 20 co-cultures. In vitro studies with wheat straw as substrate showed that the Neocallimastix with M. ruminantium co-cultures and Piromyces with M. ruminantium co-cultures exhibited higher xylanase, filter paper cellulase (FPase), ferulic acid esterase, acetyl esterase activities, in vitro dry matter digestibility, gas, CH4 , acetate production, ferulic acid and p-coumaric acid releases. The Neocallimastix frontalis Yak16 with M. ruminantium co-culture presented the strongest lignocellulose degradation ability among 20 co-cultures. Twenty fungus-methanogen co-cultures were obtained from the rumen of grazing yaks. The N. frontalis with M. ruminantium co-cultures were highly effective combination for developing a fermentative system that bioconverts lignocellulose to high activity fibre-degrading enzyme, CH4 and acetate. The N. frontalis with M. ruminantium co-cultures from yaks grazing on the Qinghai-Tibetan Plateau present great potential in lignocellulose biodegradation industry. © 2015 The Society for Applied Microbiology.

The conditional indirect effect model of women's union participation: the moderating effect of perceived union tolerance for sexual harassment.

PubMed

Mellor, Steven; Golay, Leslie M

2014-01-01

We tested a theoretically trimmed model of union participation presented by Tetrick, Shore, McClurg, and Vandenberg (2007), in which perceived union instrumentality is expected to influence participation through perceived union support. This testing was accomplished as a precursor to testing a conditional indirect effect model of women's participation--in which perceived union tolerance for sexual harassment was expected to moderate the influence of perceived support on willingness to participate in union activities. In a sample of 326 women from multiple unions, we found support for the conditional model; the influence of perceived instrumentality on willingness to participate through perceived support was moderated by perceived tolerance for harassment; specifically, the influence through perceived support was weak when perceived tolerance was high. The implications of our results are discussed in reference to need support and women's participation.

Glutathione Is Involved in Environmental Stress Responses in Rhizobium tropici, Including Acid Tolerance

PubMed Central

Riccillo, Pablo M.; Muglia, Cecilia I.; de Bruijn, Frans J.; Roe, Andrew J.; Booth, Ian R.; Aguilar, O. Mario

2000-01-01

The isolation of rhizobial strains which exhibit an intrinsic tolerance to acidic conditions has been reported and has facilitated studies on the basic mechanisms underlying acid tolerance. Rhizobium tropici strain CIAT899 displays a high intrinsic tolerance to acidity and therefore was used in this work to study the molecular basis of bacterial responses to acid conditions and other environmental stresses. We generated a collection of R. tropici CIAT899 mutants affected in acid tolerance using Tn5-luxAB mutagenesis, and one mutant strain (CIAT899-13T2), which fails to grow under acid conditions, was characterized in detail. Strain CIAT899-13T2 was found to contain a single Tn5-luxAB insertion in a gene showing a high degree of similarity with the Escherichia coli gshB gene, encoding the enzyme glutathione synthetase. Intracellular potassium pools and intracellular pH levels were found to be lower in the mutant than in the parent. The glutathione-deficient mutant was shown to be sensitive to weak organic acids, osmotic and oxidative stresses, and the presence of methylglyoxal. Glutathione restores responses to these stresses almost to wild-type levels. Our data show that in R. tropici the production of glutathione is essential for growth in extreme environmental conditions. The mutant strain CIAT899-13T2 induced effective nodules; however, it was found to be outcompeted by the wild-type strain in coinoculation experiments. PMID:10692382

Higher-level classification of the Archaea: evolution of methanogenesis and methanogens

PubMed Central

Bapteste, Éric; Brochier, Céline; Boucher, Yan

2005-01-01

We used a phylogenetic approach to analyze the evolution of methanogenesis and methanogens. We show that 23 vertically transmitted ribosomal proteins do not support the monophyly of methanogens, and propose instead that there are two distantly related groups of extant archaea that produce methane, which we have named Class I and Class II. Based on this finding, we subsequently investigated the uniqueness of the origin of methanogenesis by studying both the enzymes of methanogenesis and the proteins that synthesize its specific coenzymes. We conclude that hydrogenotrophic methanogenesis appeared only once during evolution. Genes involved in the seven central steps of the methanogenic reduction of carbon dioxide (CO2) are ubiquitous in methanogens and share a common history. This suggests that, although extant methanogens produce methane from various substrates (CO2, formate, acetate, methylated C-1 compounds), these archaea have a core of conserved enzymes that have undergone little evolutionary change. Furthermore, this core of methanogenesis enzymes seems to originate (as a whole) from the last ancestor of all methanogens and does not appear to have been horizontally transmitted to other organisms or between members of Class I and Class II. The observation of a unique and ancestral form of methanogenesis suggests that it was preserved in two independent lineages, with some instances of specialization or added metabolic flexibility. It was likely lost in the Halobacteriales, Thermoplasmatales and Archaeoglobales. Given that fossil evidence for methanogenesis dates back 2.8 billion years, a unique origin of this process makes the methanogenic archaea a very ancient taxon. PMID:15876569

Multiple Syntrophic Interactions in a Terephthalate-Degrading Methanogenic Consortium

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lykidis, Athanasios; Chen, Chia-Lung; Tringe, Susannah G.

2010-08-05

Terephthalate (TA) is one of the top 50 chemicals produced worldwide. Its production results in a TA-containing wastewater that is treated by anaerobic processes through a poorly understood methanogenic syntrophy. Using metagenomics, we characterized the methanogenic consortium tinside a hyper-mesophilic (i.e., between mesophilic and thermophilic), TA-degrading bioreactor. We identified genes belonging to dominant Pelotomaculum species presumably involved in TA degradation through decarboxylation, dearomatization, and modified ?-oxidation to H{sub 2}/CO{sub 2} and acetate. These intermediates are converted to CH{sub 4}/CO{sub 2} by three novel hyper-mesophilic methanogens. Additional secondary syntrophic interactions were predicted in Thermotogae, Syntrophus and candidate phyla OP5 and WWE1more » populations. The OP5 encodes genes capable of anaerobic autotrophic butyrate production and Thermotogae, Syntrophus and WWE1 have the genetic potential to oxidize butyrate to COsub 2}/H{sub 2} and acetate. These observations suggest that the TA-degrading consortium consists of additional syntrophic interactions beyond the standard H{sub 2}-producing syntroph ? methanogen partnership that may serve to improve community stability.« less

[Isolation and identification of cellulolytic anaerobic fungi and their associated methanogens from holstein cow].

PubMed

Sun, Meizhou; Jin, Wei; Li, Yuanfei; Mao, Shengyong; Cheng, Yanfen; Zhu, Weiyun

2014-05-04

We studied the microbial interaction between anaerobic fungi and methanogens in the rumen of Holstein Cow. Co-cultures of anaerobic fungi with indigenously associated methanogen were isolated by Hungate roll-tube technique. The anaerobic fungi were identified by morphology and 4', 6 diamidino-2-phylindole nucleus staining and the methanogens were identified by 16S rRNA gene sequencing. A total of 28 co-cultures of anaerobic fungus with indigenously associated methanogen were obtained. The anaerobic fungi in the co-cultures were identified as monocentric genera Piromyces, Neocallimastix and Caeomyces. The indigenously associated methanogens were Methanobrevibacter olleyae like and Methanobrevibacter thaueri like strains. Four different phylotypes of fungus-methanogen co-cultures were obtained, which were Piromyces/Methanobrevibacter olleyae like strains, Neocallimastix/ Methanobrevibacter olleyae like strains, Neocallimastix/Methanobrevibacter thaueri like strains and Caecomyces/ Methanobrevibacter olleyae like strains. Our study isolated and identified 28 co-cultures of anaerobic fungus and associated methanogens, which provided new materials for further study the mechanism of methane emission in the rumen.

Growth of methanogens on a Mars soil simulant.

PubMed

Kral, Timothy A; Bekkum, Curtis R; McKay, Christopher P

2004-12-01

Currently, the surface of Mars is probably too cold, too dry, and too oxidizing for life, as we know it, to exist. But the subsurface is another matter. Life forms that might exist below the surface could not obtain their energy from photosynthesis, but rather they would have to utilize chemical energy. Methanogens are one type of microorganism that might be able to survive below the surface of Mars. A potential habitat for existence of methanogens on Mars might be a geothermal source of hydrogen, possibly due to volcanic or hydrothermal activity, or the reaction of basalt and anaerobic water, carbon dioxide, which is abundant in the martian atmosphere, and of course, subsurface liquid water. We report here that certain methanogens can grow on a Mars soil simulant when supplied with carbon dioxide, molecular hydrogen, and varying amounts of water.

Analysis of methanogenic activity in a thermophilic-dry anaerobic reactor: use of fluorescent in situ hybridization.

PubMed

Montero, B; García-Morales, J L; Sales, D; Solera, R

2009-03-01

Methanogenic activity in a thermophilic-dry anaerobic reactor was determined by comparing the amount of methane generated for each of the organic loading rates with the size of the total and specific methanogenic population, as determined by fluorescent in situ hybridization. A high correlation was evident between the total methanogenic activity and retention time [-0.6988Ln(x)+2.667] (R(2) 0.8866). The total methanogenic activity increased from 0.04x10(-8) mLCH(4) cell(-1)day(-1) to 0.38x10(-8) mLCH(4) cell(-1)day(-1) while the retention time decreased, augmenting the organic loading rates. The specific methanogenic activities of H(2)-utilizing methanogens and acetate-utilizing methanogens increased until they stabilised at 0.64x10(-8) mLCH(4) cell(-1)day(-1) and 0.33x10(-8) mLCH(4) cell(-1)day(-1), respectively. The methanogenic activity of H(2)-utilizing methanogens was higher than acetate-utilizing methanogens, indicating that maintaining a low partial pressure of hydrogen does not inhibit the acetoclastic methanogenesis or the anaerobic process.

Metabolism of reduced methylated sulfur compounds in anaerobic sediments and by a pure culture of an estuarine methanogen

USGS Publications Warehouse

Kiene, R.P.; Oremland, Ronald S.; Catena, Anthony; Miller, Laurence G.; Capone, D.G.

1986-01-01

Addition of dimethylsulfide (DMS), dimethyldisulfide (DMDS), or methane thiol (MSH) to a diversity of anoxic aquatic sediments (e.g., fresh water, estuarine, alkaline/hypersaline) stimulated methane production. The yield of methane recovered from DMS was often 52 to 63%, although high concentrations of DMS (as well as MSH and DMDS) inhibited methanogenesis in some types of sediments. Production of methane from these reduced methylated sulfur compounds was blocked by 2-bromoethanesulfonic acid. Sulfate did not influence the metabolism of millimolar levels of DMS, DMDS, or MSH added to sediments. However, when DMS was added at ∼2-μM levels as [14C]DMS, metabolism by sediments resulted in a 14CH4/14CO2 ratio of only 0.06. Addition of molybdate increased the ratio to 1.8, while 2-bromoethanesulfonic acid decreased it to 0, but did not block 14CO2 production. These results indicate the methanogens and sulfate reducers compete for DMS when it is present at low concentrations; however, at high concentrations, DMS is a “noncompetitive” substrate for methanogens. Metabolism of DMS by sediments resulted in the appearance of MSH as a transient intermediate. A pure culture of an obligately methylotrophic estuarine methanogen was isolated which was capable of growth on DMS. Metabolism of DMS by the culture also resulted in the transient appearance of MSH, but the organism could grow on neither MSH nor DMDS. The culture metabolized [14C]-DMS to yield a 14CH4/14CO2 ratio of ∼2.8. Reduced methylated sulfur compounds represent a new class of substrates for methanogens and may be potential precursors of methane in a variety of aquatic habitats.

Effects of Oxygen Availability on Acetic Acid Tolerance and Intracellular pH in Dekkera bruxellensis.

PubMed

Capusoni, Claudia; Arioli, Stefania; Zambelli, Paolo; Moktaduzzaman, M; Mora, Diego; Compagno, Concetta

2016-08-01

The yeast Dekkera bruxellensis, associated with wine and beer production, has recently received attention, because its high ethanol and acid tolerance enables it to compete with Saccharomyces cerevisiae in distilleries that produce fuel ethanol. We investigated how different cultivation conditions affect the acetic acid tolerance of D. bruxellensis We analyzed the ability of two strains (CBS 98 and CBS 4482) exhibiting different degrees of tolerance to grow in the presence of acetic acid under aerobic and oxygen-limited conditions. We found that the concomitant presence of acetic acid and oxygen had a negative effect on D. bruxellensis growth. In contrast, incubation under oxygen-limited conditions resulted in reproducible growth kinetics that exhibited a shorter adaptive phase and higher growth rates than those with cultivation under aerobic conditions. This positive effect was more pronounced in CBS 98, the more-sensitive strain. Cultivation of CBS 98 cells under oxygen-limited conditions improved their ability to restore their intracellular pH upon acetic acid exposure and to reduce the oxidative damage to intracellular macromolecules caused by the presence of acetic acid. This study reveals an important role of oxidative stress in acetic acid tolerance in D. bruxellensis, indicating that reduced oxygen availability can protect against the damage caused by the presence of acetic acid. This aspect is important for optimizing industrial processes performed in the presence of acetic acid. This study reveals an important role of oxidative stress in acetic acid tolerance in D. bruxellensis, indicating that reduced oxygen availability can have a protective role against the damage caused by the presence of acetic acid. This aspect is important for the optimization of industrial processes performed in the presence of acetic acid. Copyright © 2016, American Society for Microbiology. All Rights Reserved.

Effects of Oxygen Availability on Acetic Acid Tolerance and Intracellular pH in Dekkera bruxellensis

PubMed Central

Capusoni, Claudia; Arioli, Stefania; Zambelli, Paolo; Moktaduzzaman, M.; Mora, Diego

2016-01-01

ABSTRACT The yeast Dekkera bruxellensis, associated with wine and beer production, has recently received attention, because its high ethanol and acid tolerance enables it to compete with Saccharomyces cerevisiae in distilleries that produce fuel ethanol. We investigated how different cultivation conditions affect the acetic acid tolerance of D. bruxellensis. We analyzed the ability of two strains (CBS 98 and CBS 4482) exhibiting different degrees of tolerance to grow in the presence of acetic acid under aerobic and oxygen-limited conditions. We found that the concomitant presence of acetic acid and oxygen had a negative effect on D. bruxellensis growth. In contrast, incubation under oxygen-limited conditions resulted in reproducible growth kinetics that exhibited a shorter adaptive phase and higher growth rates than those with cultivation under aerobic conditions. This positive effect was more pronounced in CBS 98, the more-sensitive strain. Cultivation of CBS 98 cells under oxygen-limited conditions improved their ability to restore their intracellular pH upon acetic acid exposure and to reduce the oxidative damage to intracellular macromolecules caused by the presence of acetic acid. This study reveals an important role of oxidative stress in acetic acid tolerance in D. bruxellensis, indicating that reduced oxygen availability can protect against the damage caused by the presence of acetic acid. This aspect is important for optimizing industrial processes performed in the presence of acetic acid. IMPORTANCE This study reveals an important role of oxidative stress in acetic acid tolerance in D. bruxellensis, indicating that reduced oxygen availability can have a protective role against the damage caused by the presence of acetic acid. This aspect is important for the optimization of industrial processes performed in the presence of acetic acid. PMID:27235432

Methanogenic pathways in Alaskan peatlands at different trophic levels with evidence from stable isotope ratios and metagenomics

NASA Astrophysics Data System (ADS)

Zhang, L.; Liu, X.; Langford, L.; Chanton, J.; Roth, S.; Schaefer, J.; Barkay, T.; Hines, M. E.

2017-12-01

To better constrain the large uncertainties in emission fluxes, it is necessary to improve the understanding of methanogenic pathways in northern peatlands with heterogeneous surface vegetation and pH. Surface vegetation is an excellent indicator of porewater pH, which heavily influences the microbial communities in peatlands. Stable C isotope ratios (d13C) have been used as a robust tool to distinguish methanogenic pathways, especially in conjunction with metagenomic analysis of the microbial communities. To link surface vegetation species compositions, pH, microbial communities, and methanogenic pathways, 15 peatland sites were studied in Fairbanks and Anchorage, Alaska in the summer of 2014. These sites were ordinated using multiple factor analysis into 3 clusters based on pH, temp, CH4 and volatile fatty acid production rates, d13C values, and surface vegetation composition. In the ombrotrophic group (pH 3.3), various Sphagna species dominanted, but included shrubs Ledum decumbens and Eriophorum vaginatum. Primary fermentation rates were slow with no CH4 detected. The fen cluster (pH 5.3) was dominated by various Carex species, and CH4 production rates were lower than those in the intermediate cluster but more enriched in 13C (-49‰). Methanosaeta and Methanosarcina were the dominant methanogens. In the intermediate trophic level (pH 4.7), Sphagnum squarrosum and Carex aquatilis were abundant. The same methanogens as in fen cluster also dominated this group, but with higher abundances, which, in part, lead to the higher CH4 production rates in this cluster. The syntrophs Syntrophobacter and Pelobacter were also more abundant than the fen sites, which may explain the d13CH4 values that were the lighetest among the three clusters (-54‰). The high methanogenic potential in the intermediate trophic sites warrant further study since they are not only present in large areas currently, but also represent the transient stage during the evolution from bog to fen in

Methane as a product of chloroethene biodegradation under methanogenic conditions

USGS Publications Warehouse

Bradley, P.M.; Chapelle, F.H.

1999-01-01

Radiometric detection headspace analyses of microcosms containing bed sediments from two geographically distinct sites indicated that 10-39% of the radiolabeled carbon transformed during anaerobic biodegradation of [1,2- 14C]trichloroethene (TCE) or [1,2-14C]vinyl chloride (VC) under methanogenic conditions was ultimately incorporated into 14CH4. The results demonstrate that, in addition to ethene, ethane, and CO2, CH4 can be a significant product of chloroethene biodegradation in some methanogenic sediments.Radiometric detection headspace analyses of microcosms containing bed sediments from two geographically distinct sites indicated that 10-39% of the radiolabeled carbon transformed during anaerobic biodegradation of [1,2-14C]trichloroethene (TCE) or [1,2-14C]vinyl chloride (VC) under methanogenic conditions was ultimately incorporated into 14CH4. The results demonstrate that, in addition to ethene, ethane, and CO2, CH4 can be a significant product of chloroethene biodegradation in some methanogenic sediments.

40 CFR 180.155 - 1-Naphthaleneacetic acid; tolerances for residues.

Code of Federal Regulations, 2011 CFR

2011-07-01

... (CONTINUED) PESTICIDE PROGRAMS TOLERANCES AND EXEMPTIONS FOR PESTICIDE CHEMICAL RESIDUES IN FOOD Specific... established for the combined residues of the plant growth regulator 1-naphthaleneacetic acid and its...

40 CFR 180.155 - 1-Naphthaleneacetic acid; tolerances for residues.

Code of Federal Regulations, 2010 CFR

2010-07-01

... (CONTINUED) PESTICIDE PROGRAMS TOLERANCES AND EXEMPTIONS FOR PESTICIDE CHEMICAL RESIDUES IN FOOD Specific... established for the combined residues of the plant growth regulator 1-naphthaleneacetic acid and its...

Long-term adaptive evolution of Leuconostoc mesenteroides for enhancement of lactic acid tolerance and production.

PubMed

Ju, Si Yeon; Kim, Jin Ho; Lee, Pyung Cheon

2016-01-01

Lactic acid has been approved by the United States Food and Drug Administration as Generally Regarded As Safe (GRAS) and is commonly used in the cosmetics, pharmaceutical, and food industries. Applications of lactic acid have also emerged in the plastics industry. Lactic acid bacteria (LAB), such as Leuconostoc and Lactobacillus , are widely used as lactic acid producers for food-related and biotechnological applications. Nonetheless, industrial mass production of lactic acid in LAB is a challenge mainly because of growth inhibition caused by the end product, lactic acid. Thus, it is important to improve acid tolerance of LAB to achieve balanced cell growth and a high titer of lactic acid. Recently, adaptive evolution has been employed as one of the strategies to improve the fitness and to induce adaptive changes in bacteria under specific growth conditions, such as acid stress. Wild-type Leuconostoc mesenteroides was challenged long term with exogenously supplied lactic acid, whose concentration was increased stepwise (for enhancement of lactic acid tolerance) during 1 year. In the course of the adaptive evolution at 70 g/L lactic acid, three mutants (LMS50, LMS60, and LMS70) showing high specific growth rates and lactic acid production were isolated and characterized. Mutant LMS70, isolated at 70 g/L lactic acid, increased d-lactic acid production up to 76.8 g/L, which was twice that in the wild type (37.8 g/L). Proteomic, genomic, and physiological analyses revealed that several possible factors affected acid tolerance, among which a mutation of ATPase ε subunit (involved in the regulation of intracellular pH) and upregulation of intracellular ammonia, as a buffering system, were confirmed to contribute to the observed enhancement of tolerance and production of d-lactic acid. During adaptive evolution under lethal stress conditions, the fitness of L. mesenteroides gradually increased to accumulate beneficial mutations according to the stress level. The

40 CFR 180.202 - p-Chlorophenoxyacetic acid; tolerances for residues.

Code of Federal Regulations, 2010 CFR

2010-07-01

... (CONTINUED) PESTICIDE PROGRAMS TOLERANCES AND EXEMPTIONS FOR PESTICIDE CHEMICAL RESIDUES IN FOOD Specific... established for the combined residues of the plant regulator p-chlorophenoxyacetic acid and its metabolite p...

40 CFR 180.202 - p-Chlorophenoxyacetic acid; tolerances for residues.

Code of Federal Regulations, 2011 CFR

2011-07-01

... (CONTINUED) PESTICIDE PROGRAMS TOLERANCES AND EXEMPTIONS FOR PESTICIDE CHEMICAL RESIDUES IN FOOD Specific... established for the combined residues of the plant regulator p-chlorophenoxyacetic acid and its metabolite p...

Microbiological characterization and specific methanogenic activity of anaerobe sludges used in urban solid waste treatment.

PubMed

Lozano, Claudia Johanna Sandoval; Mendoza, Marisol Vergara; de Arango, Mariela Carreño; Monroy, Edgar Fernando Castillo

2009-02-01

This study presents the microbiological characterization of the anaerobic sludge used in a two-stage anaerobic reactor for the treatment of organic fraction of urban solid waste (OFUSW). This treatment is one alternative for reducing solid waste in landfills at the same time producing a biogas (CH(4) and CO(2)) and an effluent that can be used as biofertilizer. The system was inoculated with sludge from a wastewater treatment plant (WWTP) (Río Frío Plant in Bucaramanga-Colombia) and a methanogenic anaerobic digester for the treatment of pig manure (Mesa de los Santos in Santander). Bacterial populations were evaluated by counting groups related to oxygen sensitivity, while metabolic groups were determined by most probable number (MPN) technique. Specific methanogenic activity (SMA) for acetate, formate, methanol and ethanol substrates was also determined. In the acidogenic reactor (R1), volatile fatty acids (VFA) reached values of 25,000 mg L(-1) and a concentration of CO(2) of 90%. In this reactor, the fermentative population was predominant (10(5)-10(6)MPN mL(-1)). The acetogenic population was (10(5)MPN mL(-1)) and the sulphate-reducing population was (10(4)-10(5)MPN mL(-1)). In the methanogenic reactor (R2), levels of CH(4) (70%) were higher than CO(2) (25%), whereas the VFA values were lower than 4000 mg L(-1). Substrate competition between sulphate-reducing (10(4)-10(5)MPN mL(-1)) and methanogenic bacteria (10(5)MPN mL(-1)) was not detected. From the SMA results obtained, acetoclastic (2.39 g COD-CH(4)g(-1)VSS(-1)day(-1)) and hydrogenophilic (0.94 g COD-CH(4)g(-1)VSS(-1)day(-1)) transformations as possible metabolic pathways used by methanogenic bacteria is suggested from the SMA results obtained. Methanotrix sp., Methanosarcina sp., Methanoccocus sp. and Methanobacterium sp. were identified.

Cinnamic Acid Analogs as Intervention Catalysts for Overcoming Antifungal Tolerance.

PubMed

Kim, Jong H; Chan, Kathleen L; Cheng, Luisa W

2017-10-21

Disruption of fungal cell wall should be an effective intervention strategy. However, the cell wall-disrupting echinocandin drugs, such as caspofungin (CAS), cannot exterminate filamentous fungal pathogens during treatment. For potency improvement of cell wall-disrupting agents (CAS, octyl gallate (OG)), antifungal efficacy of thirty-three cinnamic acid derivatives was investigated against Saccharomyces cerevisiae slt2 Δ, bck1 Δ, mutants of the mitogen-activated protein kinase (MAPK), and MAPK kinase kinase, respectively, in cell wall integrity system, and glr1 Δ, mutant of CAS-responsive glutathione reductase. Cell wall mutants were highly susceptible to four cinnamic acids (4-chloro-α-methyl-, 4-methoxy-, 4-methyl-, 3-methylcinnamic acids), where 4-chloro-α-methyl- and 4-methylcinnamic acids possessed the highest activity. Structure-activity relationship revealed that 4-methylcinnamic acid, the deoxygenated structure of 4-methoxycinnamic acid, overcame tolerance of glr1 Δ to 4-methoxycinnamic acid, indicating the significance of para substitution of methyl moiety for effective fungal control. The potential of compounds as chemosensitizers (intervention catalysts) to cell wall disruptants (viz., 4-chloro-α-methyl- or 4-methylcinnamic acids + CAS or OG) was assessed according to Clinical Laboratory Standards Institute M38-A. Synergistic chemosensitization greatly lowers minimum inhibitory concentrations of the co-administered drug/agents. 4-Chloro-α-methylcinnamic acid further overcame fludioxonil tolerance of Aspergillus fumigatus antioxidant MAPK mutants ( sakA Δ, mpkC Δ). Collectively, 4-chloro-α-methyl- and 4-methylcinnamic acids possess chemosensitizing capability to augment antifungal efficacy of conventional drug/agents, thus could be developed as target-based (i.e., cell wall disruption) intervention catalysts.

Cysteine-Accelerated Methanogenic Propionate Degradation in Paddy Soil Enrichment.

PubMed

Zhuang, Li; Ma, Jinlian; Tang, Jia; Tang, Ziyang; Zhou, Shungui

2017-05-01

Propionate degradation is a critical step during the conversion of complex organic matter under methanogenic conditions, and it requires a syntrophic cooperation between propionate-oxidizing bacteria and methanogenic archaea. Increasing evidences suggest that interspecies electron transfer for syntrophic metabolism is not limited to the reducing equivalents of hydrogen and formate. This study tested the ability of an electron shuttle to mediate interspecies electron transfer in syntrophic methanogenesis. We found that cysteine supplementation (100, 400, and 800 μM) accelerated CH 4 production from propionate in paddy soil enrichments. Of the concentrations tested, 100 μM cysteine was the most effective at enhancing propionate degradation to CH 4 , and the rates of CH 4 production and propionate degradation were increased by 109 and 79%, respectively, compared with the cysteine-free control incubations. We eliminated the possibility that the stimulatory effect of cysteine on methanogenesis was attributable to the function of cysteine as a methanogenic substrate in the presence of propionate. The potential catalytic effect involved cysteine serving as an electron carrier to mediate interspecies electron transfer in syntrophic propionate oxidization. The redox potential of cystine/cysteine, which is dependent on the concentration, might be more suitable to facilitate interspecies electron transfer between syntrophic partners at a concentration of 100 μM. Pelotomaculum, obligately syntrophic, propionate-oxidizing bacteria, and hydrogenotrophic methanogens of the family Methanobacteriaceae are predominant in cysteine-mediated methanogenic propionate degradation. The stimulatory effect of cysteine on syntrophic methanogenesis offers remarkable potential for improving the performance of anaerobic digestion and conceptually broaden strategies for interspecies electron transfer in syntrophic metabolism.

Membrane lipid physiology and toxin catabolism underlie ethanol and acetic acid tolerance in Drosophila melanogaster.

PubMed

Montooth, Kristi L; Siebenthall, Kyle T; Clark, Andrew G

2006-10-01

Drosophila melanogaster has evolved the ability to tolerate and utilize high levels of ethanol and acetic acid encountered in its rotting-fruit niche. Investigation of this phenomenon has focused on ethanol catabolism, particularly by the enzyme alcohol dehydrogenase. Here we report that survival under ethanol and acetic acid stress in D. melanogaster from high- and low-latitude populations is an integrated consequence of toxin catabolism and alteration of physical properties of cellular membranes by ethanol. Metabolic detoxification contributed to differences in ethanol tolerance between populations and acclimation temperatures via changes in both alcohol dehydrogenase and acetyl-CoA synthetase mRNA expression and enzyme activity. Independent of changes in ethanol catabolism, rapid thermal shifts that change membrane fluidity had dramatic effects on ethanol tolerance. Cold temperature treatments upregulated phospholipid metabolism genes and enhanced acetic acid tolerance, consistent with the predicted effects of restoring membrane fluidity. Phospholipase D was expressed at high levels in all treatments that conferred enhanced ethanol tolerance, suggesting that this lipid-mediated signaling enzyme may enhance tolerance by sequestering ethanol in membranes as phophatidylethanol. These results reveal new candidate genes underlying toxin tolerance and membrane adaptation to temperature in Drosophila and provide insight into how interactions between these phenotypes may underlie the maintenance of latitudinal clines in ethanol tolerance.

Genomic analysis of methanogenic archaea reveals a shift towards energy conservation

DOE PAGES

Gilmore, Sean P.; Henske, John K.; Sexton, Jessica A.; ...

2017-08-21

The metabolism of archaeal methanogens drives methane release into the environment and is critical to understanding global carbon cycling. Methanogenesis operates at a very low reducing potential compared to other forms of respiration and is therefore critical to many anaerobic environments. Harnessing or altering methanogen metabolism has the potential to mitigate global warming and even be utilized for energy applications. Here, we report draft genome sequences for the isolated methanogens Methanobacterium bryantii, Methanosarcina spelaei, Methanosphaera cuniculi, and Methanocorpusculum parvum. These anaerobic, methane-producing archaea represent a diverse set of isolates, capable of methylotrophic, acetoclastic, and hydrogenotrophic methanogenesis. Assembly and analysis ofmore » the genomes allowed for simple and rapid reconstruction of metabolism in the four methanogens. Comparison of the distribution of Clusters of Orthologous Groups (COG) proteins to a sample of genomes from the RefSeq database revealed a trend towards energy conservation in genome composition of all methanogens sequenced. Further analysis of the predicted membrane proteins and transporters distinguished differing energy conservation methods utilized during methanogenesis, such as chemiosmotic coupling in Msar. spelaei and electron bifurcation linked to chemiosmotic coupling in Mbac. bryantii and Msph. cuniculi. Methanogens occupy a unique ecological niche, acting as the terminal electron acceptors in anaerobic environments, and their genomes display a significant shift towards energy conservation. The genome-enabled reconstructed metabolisms reported here have significance to diverse anaerobic communities and have led to proposed substrate utilization not previously reported in isolation, such as formate and methanol metabolism in Mbac. bryantii and CO 2 metabolism in Msph. cuniculi. The newly proposed substrates establish an important foundation with which to decipher how methanogens

Genomic analysis of methanogenic archaea reveals a shift towards energy conservation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gilmore, Sean P.; Henske, John K.; Sexton, Jessica A.

The metabolism of archaeal methanogens drives methane release into the environment and is critical to understanding global carbon cycling. Methanogenesis operates at a very low reducing potential compared to other forms of respiration and is therefore critical to many anaerobic environments. Harnessing or altering methanogen metabolism has the potential to mitigate global warming and even be utilized for energy applications. Here, we report draft genome sequences for the isolated methanogens Methanobacterium bryantii, Methanosarcina spelaei, Methanosphaera cuniculi, and Methanocorpusculum parvum. These anaerobic, methane-producing archaea represent a diverse set of isolates, capable of methylotrophic, acetoclastic, and hydrogenotrophic methanogenesis. Assembly and analysis ofmore » the genomes allowed for simple and rapid reconstruction of metabolism in the four methanogens. Comparison of the distribution of Clusters of Orthologous Groups (COG) proteins to a sample of genomes from the RefSeq database revealed a trend towards energy conservation in genome composition of all methanogens sequenced. Further analysis of the predicted membrane proteins and transporters distinguished differing energy conservation methods utilized during methanogenesis, such as chemiosmotic coupling in Msar. spelaei and electron bifurcation linked to chemiosmotic coupling in Mbac. bryantii and Msph. cuniculi. Methanogens occupy a unique ecological niche, acting as the terminal electron acceptors in anaerobic environments, and their genomes display a significant shift towards energy conservation. The genome-enabled reconstructed metabolisms reported here have significance to diverse anaerobic communities and have led to proposed substrate utilization not previously reported in isolation, such as formate and methanol metabolism in Mbac. bryantii and CO 2 metabolism in Msph. cuniculi. The newly proposed substrates establish an important foundation with which to decipher how methanogens

The efficacy and tolerability of 5-aminolevulinic acid 5% thermosetting gel photodynamic therapy (PDT) in the treatment of mild-to-moderate acne vulgaris. A two-center, prospective assessor-blinded, proof-of-concept study.

PubMed

Serini, Stefano Maria; Cannizzaro, Maria Vittoria; Dattola, Annunziata; Garofalo, Virginia; Del Duca, Esther; Ventura, Alessandra; Milani, Massimo; Campione, Elena; Bianchi, Luca

2018-05-22

Acne vulgaris is a chronic inflammatory skin disease, commonly treated with topical or systemic drugs, according to the severity of the condition. Retinoids and antibiotic compounds are considered cornerstone approaches in this condition. However, low adherence to the therapy and the issue of bacterial resistance undermine the efficacy in the long term. Photodynamic therapy (PDT) with 20% aminolevulinic acid (ALA) has shown to be effective in the treatment of inflammatory acne. Skin tolerability, however, could be a limiting factor for a widespread use of this approach. A new formulation of 5% ALA in thermosetting gel has been recently available. This formulation allows a more convenient application procedure without occlusion and better and more efficient release of the active compound in comparison with traditional ALA formulations like creams or ointments. To evaluate in a two-center, assessor-blinded, prospective, proof-of-concept study, the efficacy, and tolerability of red-light (630 nm) PDT with a new 5-ALA "low-dose" topical gel formulation (5%) in the treatment of inflammatory mild-to-moderate acne vulgaris (AV). A total of 35 subjects with moderate AV of the face (mean age: 24 ± 8 years, 13 men and 22 women) were enrolled, after their written informed consent. The primary outcome was the evolution of GAG (Global Acne Grade System) score at baseline and after an average of three, 630-nm, 15-minute, PDT sessions, performed every 2 weeks. GAG score was also calculated in a follow-up visit 6 months after the last PDT session. Skin tolerability was assessed during PDT sessions with a patient-reported discomfort level evaluation score from 0 (no discomfort at all) to 3 (severe discomfort). At baseline, the GAG score was 21 ± 6. After the last PDT session, the GAG score evaluated in a blinded fashion (digital photographs) was significantly reduced to 6.5 ± 5.7, representing a 70% reduction (P = .0001, Wilcoxon test; mean difference 14.9; 95% CI of

Distribution of Sulfate-Reducing and Methanogenic Bacteria in Anaerobic Aggregates Determined by Microsensor and Molecular Analyses

PubMed Central

Santegoeds, Cecilia M.; Damgaard, Lars Riis; Hesselink, Gijs; Zopfi, Jakob; Lens, Piet; Muyzer, Gerard; de Beer, Dirk

1999-01-01

Using molecular techniques and microsensors for H2S and CH4, we studied the population structure of and the activity distribution in anaerobic aggregates. The aggregates originated from three different types of reactors: a methanogenic reactor, a methanogenic-sulfidogenic reactor, and a sulfidogenic reactor. Microsensor measurements in methanogenic-sulfidogenic aggregates revealed that the activity of sulfate-reducing bacteria (2 to 3 mmol of S2− m−3 s−1 or 2 × 10−9 mmol s−1 per aggregate) was located in a surface layer of 50 to 100 μm thick. The sulfidogenic aggregates contained a wider sulfate-reducing zone (the first 200 to 300 μm from the aggregate surface) with a higher activity (1 to 6 mmol of S2− m−3 s−1 or 7 × 10−9 mol s−1 per aggregate). The methanogenic aggregates did not show significant sulfate-reducing activity. Methanogenic activity in the methanogenic-sulfidogenic aggregates (1 to 2 mmol of CH4 m−3 s−1 or 10−9 mmol s−1 per aggregate) and the methanogenic aggregates (2 to 4 mmol of CH4 m−3 s−1 or 5 × 10−9 mmol s−1 per aggregate) was located more inward, starting at ca. 100 μm from the aggregate surface. The methanogenic activity was not affected by 10 mM sulfate during a 1-day incubation. The sulfidogenic and methanogenic activities were independent of the type of electron donor (acetate, propionate, ethanol, or H2), but the substrates were metabolized in different zones. The localization of the populations corresponded to the microsensor data. A distinct layered structure was found in the methanogenic-sulfidogenic aggregates, with sulfate-reducing bacteria in the outer 50 to 100 μm, methanogens in the inner part, and Eubacteria spp. (partly syntrophic bacteria) filling the gap between sulfate-reducing and methanogenic bacteria. In methanogenic aggregates, few sulfate-reducing bacteria were detected, while methanogens were found in the core. In the sulfidogenic aggregates, sulfate-reducing bacteria were

Metagenomic identification of active methanogens and methanotrophs in serpentinite springs of the Voltri Massif, Italy.

PubMed

Brazelton, William J; Thornton, Christopher N; Hyer, Alex; Twing, Katrina I; Longino, August A; Lang, Susan Q; Lilley, Marvin D; Früh-Green, Gretchen L; Schrenk, Matthew O

2017-01-01

The production of hydrogen and methane by geochemical reactions associated with the serpentinization of ultramafic rocks can potentially support subsurface microbial ecosystems independent of the photosynthetic biosphere. Methanogenic and methanotrophic microorganisms are abundant in marine hydrothermal systems heavily influenced by serpentinization, but evidence for methane-cycling archaea and bacteria in continental serpentinite springs has been limited. This report provides metagenomic and experimental evidence for active methanogenesis and methanotrophy by microbial communities in serpentinite springs of the Voltri Massif, Italy. Methanogens belonging to family Methanobacteriaceae and methanotrophic bacteria belonging to family Methylococcaceae were heavily enriched in three ultrabasic springs (pH 12). Metagenomic data also suggest the potential for hydrogen oxidation, hydrogen production, carbon fixation, fermentation, and organic acid metabolism in the ultrabasic springs. The predicted metabolic capabilities are consistent with an active subsurface ecosystem supported by energy and carbon liberated by geochemical reactions within the serpentinite rocks of the Voltri Massif.

Volatile hydrocarbons inhibit methanogenic crude oil degradation

PubMed Central

Sherry, Angela; Grant, Russell J.; Aitken, Carolyn M.; Jones, D. Martin; Head, Ian M.; Gray, Neil D.

2014-01-01

Methanogenic degradation of crude oil in subsurface sediments occurs slowly, but without the need for exogenous electron acceptors, is sustained for long periods and has enormous economic and environmental consequences. Here we show that volatile hydrocarbons are inhibitory to methanogenic oil biodegradation by comparing degradation of an artificially weathered crude oil with volatile hydrocarbons removed, with the same oil that was not weathered. Volatile hydrocarbons (nC5–nC10, methylcyclohexane, benzene, toluene, and xylenes) were quantified in the headspace of microcosms. Aliphatic (n-alkanes nC12–nC34) and aromatic hydrocarbons (4-methylbiphenyl, 3-methylbiphenyl, 2-methylnaphthalene, 1-methylnaphthalene) were quantified in the total hydrocarbon fraction extracted from the microcosms. 16S rRNA genes from key microorganisms known to play an important role in methanogenic alkane degradation (Smithella and Methanomicrobiales) were quantified by quantitative PCR. Methane production from degradation of weathered oil in microcosms was rapid (1.1 ± 0.1 μmol CH4/g sediment/day) with stoichiometric yields consistent with degradation of heavier n-alkanes (nC12–nC34). For non-weathered oil, degradation rates in microcosms were significantly lower (0.4 ± 0.3 μmol CH4/g sediment/day). This indicated that volatile hydrocarbons present in the non-weathered oil inhibit, but do not completely halt, methanogenic alkane biodegradation. These findings are significant with respect to rates of biodegradation of crude oils with abundant volatile hydrocarbons in anoxic, sulphate-depleted subsurface environments, such as contaminated marine sediments which have been entrained below the sulfate-reduction zone, as well as crude oil biodegradation in petroleum reservoirs and contaminated aquifers. PMID:24765087

Methanogenic community composition in an organic waste mixture in an anaerobic bioreactor

NASA Astrophysics Data System (ADS)

Gryta, Agata; Oszust, Karolina; Brzezińska, Małgorzata; Ziemiński, Krzysztof; Bilińska-Wielgus, Nina; Frąc, Magdalena

2017-07-01

The aim of the study was to elucidate the substantial relationship between the compositions of methanogen community that assembles in the anaerobic digester mass and link it to methane production activity. The results of the metagenomic studies were used to evaluate how the methanogen structure changes during an anaerobic digestion process under various waste retention times (21, 23, 25, 29, 33, 39, 47 and 61 days). Phylogenetically coherent populations of methanogens were assessed by 16S rRNA gene next-generation sequencing and terminal restriction fragment length polymorphism fingerprinting of a specific molecular marker, the mcrA gene. The results indicated multiple phylogenetically diverse methanogen populations associated with the various steps of anaerobic digestion. The stages of the anaerobic digestion process and waste retention times determine the microbial composition. The most dominant and acclimated microbial communities in all samples belonged to the genera Methanosaeta and Methanobacterium. The methane yield was consistent with the results of the microbial community structure, which indicated that acetotrophic Methanosaeta was the most active and most important during the methanogenic stage.

Oligonucleotide primers, probes and molecular methods for the environmental monitoring of methanogenic archaea

PubMed Central

Narihiro, Takashi; Sekiguchi, Yuji

2011-01-01

Summary For the identification and quantification of methanogenic archaea (methanogens) in environmental samples, various oligonucleotide probes/primers targeting phylogenetic markers of methanogens, such as 16S rRNA, 16S rRNA gene and the gene for the α‐subunit of methyl coenzyme M reductase (mcrA), have been extensively developed and characterized experimentally. These oligonucleotides were designed to resolve different groups of methanogens at different taxonomic levels, and have been widely used as hybridization probes or polymerase chain reaction primers for membrane hybridization, fluorescence in situ hybridization, rRNA cleavage method, gene cloning, DNA microarray and quantitative polymerase chain reaction for studies in environmental and determinative microbiology. In this review, we present a comprehensive list of such oligonucleotide probes/primers, which enable us to determine methanogen populations in an environment quantitatively and hierarchically, with examples of the practical applications of the probes and primers. PMID:21375721

Improved acid tolerance of Lactobacillus pentosus by error-prone whole genome amplification.

PubMed

Ye, Lidan; Zhao, Hua; Li, Zhi; Wu, Jin Chuan

2013-05-01

Acid tolerance of Lactobacillus pentosus ATCC 8041 was improved by error-prone amplification of its genomic DNA using random primers and Taq DNA polymerase. The resulting amplification products were transferred into wild-type L. pentosus by electroporation and the transformants were screened for growth on low-pH agar plates. After only one round of mutation, one mutant (MT3) was identified that was able to completely consume 20 g/L of glucose to produce lactic acid at a yield of 95% in 1L MRS medium at pH 3.8 within 36 h, whereas no growth or lactic acid production was observed for the wild-type strain under the same conditions. The acid tolerance of mutant MT3 remained genetically stable for at least 25 subcultures. Therefore, the error-prone whole genome amplification technique is a very powerful tool for improving phenotypes of this lactic acid bacterium and may also be applicable for other microorganisms. Copyright © 2012 Elsevier Ltd. All rights reserved.

Enrichment of lignocellulose-degrading microbial communities from natural and engineered methanogenic environments.

PubMed

Ozbayram, Emine Gozde; Kleinsteuber, Sabine; Nikolausz, Marcell; Ince, Bahar; Ince, Orhan

2018-01-01

The aim of this study was to develop an effective bioaugmentation concept for anaerobic digesters treating lignocellulosic biomass such as straw. For that purpose, lignocellulose-degrading methanogenic communities were enriched on wheat straw from cow and goat rumen fluid as well as from a biogas reactor acclimated to lignocellulosic biomass (sorghum as mono-substrate). The bacterial communities of the enriched cultures and the different inocula were examined by 454 amplicon sequencing of 16S rRNA genes while the methanogenic archaeal communities were analyzed by terminal restriction fragment length polymorphism (T-RFLP) fingerprinting of the mcrA gene. Bacteroidetes was the most abundant phylum in all samples. Within the Bacteroidetes phylum, Bacteroidaceae was the most abundant family in the rumen-derived enrichment cultures, whereas Porphyromonadaceae was the predominant one in the reactor-derived culture. Additionally, the enrichment procedure increased the relative abundance of Ruminococcaceae (phylum: Firmicutes) in all cultures. T-RFLP profiles of the mcrA gene amplicons highlighted that the ruminal methanogenic communities were composed of hydrogenotrophic methanogens dominated by the order Methanobacteriales regardless of the host species. The methanogenic communities changed significantly during the enrichment procedure, but still the strict hydrogenotrophic Methanobacteriales and Methanomicrobiales were the predominant orders in the enrichment cultures. The bioaugmentation potential of the enriched methanogenic cultures will be evaluated in further studies.

Growth and analysis of anaerobic wastewater methanogens using microfluidics

NASA Astrophysics Data System (ADS)

Steinhaus, Ben

2005-11-01

A micro-bioreactor (μBR) with a total system volume of 5 μl was developed using microfluidics and used to study the anaerobic waste-water methanogen methanosaeta concilli. The μBR was contained inside of an anaerobic chamber designed to be placed directly under an inverted light microscope while maintaining the reactor under a N2/CO2 gas mixture. Methanogens were cultured for periods of up to 3 months inside channels of varying width. The varying channel widths created varying fluid velocities and hence varying shear-rates inside the μBR. This allowed for direct study of the behavior and response of the anaerobe to varying shear-rates. After completion of the study, fluorescent in situ hybridization (FISH) was performed directly inside the microchannels to allow for further analysis and identification of the methanogens.

A lignocellulosic hydrolysate-tolerant Aurantiochytrium sp. mutant strain for docosahexaenoic acid production.

PubMed

Qi, Feng; Zhang, Mingliang; Chen, Youwei; Jiang, Xianzhang; Lin, Jinxin; Cao, Xiao; Huang, Jianzhong

2017-03-01

To utilize lignocellulosic hydrolysate for docosahexaenoic acid (DHA) production, a novel mutant Aurantiochytrium sp. FN21 with strong tolerance against inhibitory lignocellulosic hydrolysate was obtained through continuous domestication processes from the parent strain Aurantiochytrium sp. FJU-512. Aurantiochytrium sp. FN21 can accumulate 21.3% and 30.7% more DHA compared to its parent strain cultured in fermentation medium and a medium with 50% (v/v) sugarcane bagasse hydrolysate (SBH), respectively. After optimization with different nitrogen sources, the highest lipid (11.84g/L) and DHA (3.15g/L) production were achieved in SBH. The results demonstrated that Aurantiochytrium sp. FN21 has the commercial applications for DHA production using lignocellulosic hydrolysate. In order to elucidate the tolerance mechanism, transcriptomic profiling of the two strains was studied. The highly up-regulated genes and corresponding cellular pathways (TCA cycle, amino acid biosynthesis, fatty acid metabolism and degradation of aromatic compounds) are considered to be associated with the hydrolysate-tolerance of Aurantiochytrium sp. FN21. Copyright © 2016 Elsevier Ltd. All rights reserved.

Point mutation of H3/H4 histones affects acetic acid tolerance in Saccharomyces cerevisiae.

PubMed

Liu, Xiangyong; Zhang, Xiaohua; Zhang, Zhaojie

2014-10-10

The molecular mechanism of acetic acid tolerance in yeast remains unclear despite of its importance for efficient cellulosic ethanol production. In this study, we examined the effects of histone H3/H4 point mutations on yeast acetic acid tolerance by comprehensively screening a histone H3/H4 mutant library. A total of 24 histone H3/H4 mutants (six acetic acid resistant and 18 sensitive) were identified. Compared to the wild-type strain, the histone acetic acid-resistant mutants exhibited improved ethanol fermentation performance under acetic acid stress. Genome-wide transcriptome analysis revealed that changes in the gene expression in the acetic acid-resistant mutants H3 K37A and H4 K16Q were mainly related to energy production, antioxidative stress. Our results provide novel insights into yeast acetic acid tolerance on the basis of histone, and suggest a novel approach to improve ethanol production by altering the histone H3/H4 sequences. Copyright © 2014 Elsevier B.V. All rights reserved.

Growth of methylaminotrophic, acetotrophic and hydrogenotrophic methanogenic bacteria on artificial supports.

PubMed

Urrutia, H; Vidal, R; Baeza, M; Reyes, J E; Aspe, E

1997-06-01

The efficiency of organic matter degradation in attached biomass reactors depends on the suitable selection of artificial support for the retention of bacterial communities. We have studied the growth on glass and clay beads of methylaminotrophic, acetotrophic and hydrogenotrophic methanogenic bacterial communities isolated from anaerobic reactors. Bacterial counts were performed by the standard MPN technique. Experiments were performed in 50 ml vials for 12 days at 35 degrees C. Increase in the counts of methylaminotrophic and hydrogenotrophic methanogens occurred on both glass and clay beads. The latter support material also stimulated the growth rate of methylaminotrophic methanogens.

Global transcriptional profiling of a cold-tolerant rice variety under moderate cold stress reveals different cold stress response mechanisms.

PubMed

Zhao, Junliang; Zhang, Shaohong; Yang, Tifeng; Zeng, Zichong; Huang, Zhanghui; Liu, Qing; Wang, Xiaofei; Leach, Jan; Leung, Hei; Liu, Bin

2015-07-01

Gene expression profiling under severe cold stress (4°C) has been conducted in plants including rice. However, rice seedlings are frequently exposed to milder cold stresses under natural environments. To understand the responses of rice to milder cold stress, a moderately low temperature (8°C) was used for cold treatment prior to genome-wide profiling of gene expression in a cold-tolerant japonica variety, Lijiangxintuanheigu (LTH). A total of 5557 differentially expressed genes (DEGs) were found at four time points during moderate cold stress. Both the DEGs and differentially expressed transcription factor genes were clustered into two groups based on their expression, suggesting a two-phase response to cold stress and a determinative role of transcription factors in the regulation of stress response. The induction of OsDREB2A under cold stress is reported for the first time in this study. Among the anti-oxidant enzyme genes, glutathione peroxidase (GPX) and glutathione S-transferase (GST) were upregulated, suggesting that the glutathione system may serve as the main reactive oxygen species (ROS) scavenger in LTH. Changes in expression of genes in signal transduction pathways for auxin, abscisic acid (ABA) and salicylic acid (SA) imply their involvement in cold stress responses. The induction of ABA response genes and detection of enriched cis-elements in DEGs suggest that ABA signaling pathway plays a dominant role in the cold stress response. Our results suggest that rice responses to cold stress vary with the specific temperature imposed and the rice genotype. © 2014 Scandinavian Plant Physiology Society.

YfdW and YfdU Are Required for Oxalate-Induced Acid Tolerance in Escherichia coli K-12

PubMed Central

Fontenot, Elise M.; Ezelle, Karen E.; Gabreski, Lauren N.; Giglio, Eleanor R.; McAfee, John M.; Mills, Alexandria C.; Qureshi, Maryam N.; Salmon, Kristin M.

2013-01-01

Escherichia coli has several mechanisms for surviving low-pH stress. We report that oxalic acid, a small-chain organic acid (SCOA), induces a moderate acid tolerance response (ATR) in two ways. Adaptation of E. coli K-12 at pH 5.5 with 50 mM oxalate and inclusion of 25 mM oxalate in pH 3.0 minimal challenge medium separately conferred protection, with 67% ± 7% and 87% ± 17% survival after 2 h, respectively. The combination of oxalate adaptation and oxalate supplementation in the challenge medium resulted in increased survival over adaptation or oxalate in the challenge medium alone. The enzymes YfdW, a formyl coenzyme A (CoA) transferase, and YfdU, an oxalyl-CoA decarboxylase, are required for the adaptation effect but not during challenge. Unlike other SCOAs, this oxalate ATR is not a part of the RpoS regulon but appears to be linked to the signal protein GadE. We theorize that this oxalate ATR could enhance the pathogenesis of virulent E. coli consumed with oxalate-containing foods like spinach. PMID:23335415

Sensitivity and adaptability of methanogens to perchlorates: Implications for life on Mars

NASA Astrophysics Data System (ADS)

Kral, Timothy A.; Goodhart, Timothy H.; Harpool, Joshua D.; Hearnsberger, Christopher E.; McCracken, Graham L.; McSpadden, Stanley W.

2016-01-01

In 2008, the Mars Phoenix Lander discovered perchlorate at its landing site, and in 2012, the Curiosity rover confirmed the presence of perchlorate on Mars. The research reported here was designed to determine if certain methanogens could grow in the presence of three different perchlorate salt solutions. The methanogens tested were Methanothermobacter wolfeii, Methanosarcina barkeri, Methanobacterium formicicum and Methanococcus maripaludis. Media were prepared containing 0%, 0.5%, 1.0%, 2%, 5% and 10% wt/vol magnesium perchlorate, sodium perchlorate, or calcium perchlorate. Organisms were inoculated into their respective media followed by incubation at each organism's growth temperature. Methane production, commonly used to measure methanogen growth, was measured by gas chromatography of headspace gas samples. Methane concentrations varied with species and perchlorate salt tested. However, all four methanogens produced substantial levels of methane in the presence of up to 1.0% perchlorate, but not higher. The standard procedure for growing methanogens typically includes sodium sulfide, a reducing agent, to reduce residual molecular oxygen. However, the sodium sulfide may have been reducing the perchlorate, thus allowing for growth of the methanogens. To investigate this possibility, experiments were conducted where stainless steel nails were used instead of sodium sulfide as the reducing agent. Prior to the addition of perchlorate and inoculation, the nails were removed from the liquid medium. Just as in the prior experiments, the methanogens produced methane at comparable levels to those seen with sodium sulfide as the reductant, indicating that sodium sulfide did not reduce the perchlorate to any significant extent. Additionally, cells metabolizing in 1% perchlorate were transferred to 2%, cells metabolizing in 2% were transferred to 5%, and finally cells metabolizing in 5% were transferred to 10%. All four species produced methane at 2% and 5%, but not 10

Anaerobic biodegradability and methanogenic toxicity of key constituents in copper chemical mechanical planarization effluents of the semiconductor industry.

PubMed

Hollingsworth, Jeremy; Sierra-Alvarez, Reyes; Zhou, Michael; Ogden, Kimberly L; Field, Jim A

2005-06-01

Copper chemical mechanical planarization (CMP) effluents can account for 30-40% of the water discharge in semiconductor manufacturing. CMP effluents contain high concentrations of soluble copper and a complex mixture of organic constituents. The aim of this study is to perform a preliminary assessment of the treatability of CMP effluents in anaerobic sulfidogenic bioreactors inoculated with anaerobic granular sludge by testing individual compounds expected in the CMP effluents. Of all the compounds tested (copper (II), benzotriazoles, polyethylene glycol (M(n) 300), polyethylene glycol (M(n) 860) monooleate, perfluoro-1-octane sulfonate, citric acid, oxalic acid and isopropanol) only copper was found to be inhibitory to methanogenic activity at the concentrations tested. Most of the organic compounds tested were biodegradable with the exception of perfluoro-1-octane sulfonate and benzotriazoles under sulfate reducing conditions and with the exception of the same compounds as well as Triton X-100 under methanogenic conditions. The susceptibility of key components in CMP effluents to anaerobic biodegradation combined with their low microbial inhibition suggest that CMP effluents should be amenable to biological treatment in sulfate reducing bioreactors.

Copper tolerance of brown-rot fungi : time course of oxalic acid production

Treesearch

Frederick Green; Carol A. Clausen

2003-01-01

The increase in the use of non-arsenical copper-based wood preservatives in response to environmental concerns has been accompanied by interest in copper-tolerant decay fungi. Oxalic acid production by brown-rot fungi has been proposed as one mechanism of copper tolerance. Fifteen brown-rot fungi representing the genera Postia, Wolfiporia, Meruliporia, Gloeophyllum,...

Deletion of JJJ1 improves acetic acid tolerance and bioethanol fermentation performance of Saccharomyces cerevisiae strains.

PubMed

Wu, Xuechang; Zhang, Lijie; Jin, Xinna; Fang, Yahong; Zhang, Ke; Qi, Lei; Zheng, Daoqiong

2016-07-01

To improve tolerance to acetic acid that is present in lignocellulosic hydrolysates and affects bioethanol production by Saccharomyces cerevisiae. Saccharomyces cerevisiae strains with improved tolerance to acetic acid were obtained through deletion of the JJJ1 gene. The lag phase of the JJJ1 deletion mutant BYΔJJJ1 was ~16 h shorter than that of the parent strain, BY4741, when the fermentation medium contained 4.5 g acetic acid/l. Additionally, the specific ethanol production rate of BYΔJJJ1 was increased (0.057 g/g h) compared to that of the parent strain (0.051 g/g h). Comparative transcription and physiological analyses revealed higher long chain fatty acid, trehalose, and catalase contents might be critical factors responsible for the acetic acid resistance of JJJ1 knockout strains. JJJ1 deletion improves acetic acid tolerance and ethanol fermentation performance of S. cerevisiae.

Metagenomic identification of active methanogens and methanotrophs in serpentinite springs of the Voltri Massif, Italy

PubMed Central

Thornton, Christopher N.; Hyer, Alex; Twing, Katrina I.; Longino, August A.; Lang, Susan Q.; Lilley, Marvin D.; Früh-Green, Gretchen L.; Schrenk, Matthew O.

2017-01-01

The production of hydrogen and methane by geochemical reactions associated with the serpentinization of ultramafic rocks can potentially support subsurface microbial ecosystems independent of the photosynthetic biosphere. Methanogenic and methanotrophic microorganisms are abundant in marine hydrothermal systems heavily influenced by serpentinization, but evidence for methane-cycling archaea and bacteria in continental serpentinite springs has been limited. This report provides metagenomic and experimental evidence for active methanogenesis and methanotrophy by microbial communities in serpentinite springs of the Voltri Massif, Italy. Methanogens belonging to family Methanobacteriaceae and methanotrophic bacteria belonging to family Methylococcaceae were heavily enriched in three ultrabasic springs (pH 12). Metagenomic data also suggest the potential for hydrogen oxidation, hydrogen production, carbon fixation, fermentation, and organic acid metabolism in the ultrabasic springs. The predicted metabolic capabilities are consistent with an active subsurface ecosystem supported by energy and carbon liberated by geochemical reactions within the serpentinite rocks of the Voltri Massif. PMID:28149702

Improving the acetic acid tolerance and fermentation of Acetobacter pasteurianus by nucleotide excision repair protein UvrA.

PubMed

Zheng, Yu; Wang, Jing; Bai, Xiaolei; Chang, Yangang; Mou, Jun; Song, Jia; Wang, Min

2018-05-21

Acetic acid bacteria (AAB) are widely used in acetic acid fermentation due to their remarkable ability to oxidize ethanol and high tolerance against acetic acid. In Acetobacter pasteurianus, nucleotide excision repair protein UvrA was up-regulated 2.1 times by acetic acid when compared with that without acetic acid. To study the effects of UvrA on A. pasteurianus acetic acid tolerance, uvrA knockout strain AC2005-ΔuvrA, uvrA overexpression strain AC2005 (pMV24-uvrA), and the control strain AC2005 (pMV24), were constructed. One percent initial acetic acid was almost lethal to AC2005-ΔuvrA. However, the biomass of the UvrA overexpression strain was higher than that of the control under acetic acid concentrations. After 6% acetic acid shock for 20 and 40 min, the survival ratios of AC2005 (pMV24-uvrA) were 2 and 0.12%, respectively; however, they were 1.5 and 0.06% for the control strain AC2005 (pMV24). UvrA overexpression enhanced the acetification rate by 21.7% when compared with the control. The enzymes involved in ethanol oxidation and acetic acid tolerance were up-regulated during acetic acid fermentation due to the overexpression of UvrA. Therefore, in A. pasteurianus, UvrA could be induced by acetic acid and is related with the acetic acid tolerance by protecting the genome against acetic acid to ensure the protein expression and metabolism.

Relationship between methanogenic archaea and subgingival microbial complexes in human periodontitis.

PubMed

Horz, H P; Robertz, N; Vianna, M E; Henne, K; Conrads, G

2015-10-01

We compared the amounts of methanogenic archaea with ten of the most important periodontal pathogens in 125 clinical samples. Correlation analysis suggests that the support of the periodontitis-associated bacterial consortium by methanogenic archaea may be driven through direct or indirect interactions with Prevotella intermedia. Copyright © 2015 Elsevier Ltd. All rights reserved.

A comment on methanogenic bacteria and the primitive ecology

NASA Technical Reports Server (NTRS)

Woese, C. R.

1977-01-01

As the phenotype of methanogenic bacteria is suggested to have been one of the major factors creating a dynamic balance between CO2 and CH4 in the primitive atmosphere, these organisms are thought to be very ancient. Their antiquity may be further postulated by comparative characterization of their ribosomal RNA. Accepting this antiquity, it is concluded that a carbon-dioxide-methane cycle, driven by photosynthesis, was the major carbon cycle in primitive ecology, and that photosynthesis and methanogens were thus contemporaneous.

Identification and analysis of proton-translocating pyrophosphatases in the methanogenic archaeon Methansarcina mazei.

PubMed

Bäumer, Sebastian; Lentes, Sabine; Gottschalk, Gerhard; Deppenmeier, Uwe

2002-03-01

Analysis of genome sequence data from the methanogenic archaeon Methanosarcina mazei Gö1 revealed the existence of two open reading frames encoding proton-translocating pyrophosphatases (PPases). These open reading frames are linked by a 750-bp intergenic region containing TC-rich stretches and are transcribed in opposite directions. The corresponding polypeptides are referred to as Mvp1 and Mvp2 and consist of 671 and 676 amino acids, respectively. Both enzymes represent extremely hydrophobic, integral membrane proteins with 15 predicted transmembrane segments and an overall amino acid sequence similarity of 50.1%. Multiple sequence alignments revealed that Mvp1 is closely related to eukaryotic PPases, whereas Mvp2 shows highest homologies to bacterial PPases. Northern blot experiments with RNA from methanol-grown cells harvested in the mid-log growth phase indicated that only Mvp2 was produced under these conditions. Analysis of washed membranes showed that Mvp2 had a specific activity of 0.34 U mg (protein)(-1). Proton translocation experiments with inverted membrane vesicles prepared from methanol-grown cells showed that hydrolysis of 1 mol of pyrophosphate was coupled to the translocation of about 1 mol of protons across the cytoplasmic membrane. Appropriate conditions for mvp1 expression could not be determined yet. The pyrophosphatases of M. mazei Gö1 represent the first examples of this enzyme class in methanogenic archaea and may be part of their energy-conserving system.

Efficacy of topical azelaic acid gel in the treatment of mild-moderate acne vulgaris.

PubMed

Iraji, Fariba; Sadeghinia, Ali; Shahmoradi, Zabiholahi; Siadat, Amir Hossein; Jooya, Abolfazl

2007-01-01

Twenty percent azelaic acid gel is recommended as a topical treatment for acne due to its favorable profile. Our objective in this study was to evaluate the efficacy of 20% azelaic acid gel in the treatment of mild to moderate acne vulgaris. This was a double blind, randomized clinical trial. Sixty patients with mild to moderate acne vulgaris were selected randomly to receive either azelaic acid gel or the vehicle gel alone. Patients were followed up every 15 days for a period of 45 days. The number of lesions and the acne severity index (ASI) were recorded and compared using Student's t-test. Total lesion count was reduced by 60.6% and 19.9% by azelaic acid gel and the placebo respectively (P = 0.002). ASI was reduced by 65.2% and 21.3% by azelaic acid gel and the placebo respectively (P = 0.001), i.e, azelaic acid gel was 3.06 times more effective than the placebo in reducing ASI. Azelaic acid gel can be used as an effective treatment in mild to moderate acne vulgaris.

Metabolomics analysis of rice responses to salinity stress revealed elevation of serotonin, and gentisic acid levels in leaves of tolerant varieties.

PubMed

Gupta, Poulami; De, Bratati

2017-07-03

A GC-MS based analytical approach was undertaken to understand the metabolomic responses of seedlings of 2 salt sensitive (Sujala and MTU 7029) and 2 tolerant varieties (Bhutnath, and Nonabokra) of indica rice (Oryza sativa L.) to NaCl induced stress. The 4 varieties responded differently to NaCl treatment with respect to the conserved primary metabolites (sugars, polyols, amino acids, organic acids and certain purine derivatives) of the leaf of rice seedlings. However, there were significant differences in salt induced production of chorismic acid derivatives. Serotonin level was increased in both the salt tolerant varieties in response to NaCl induced stress. In both the salt tolerant varieties, increased production of the signaling molecule gentisic acid in response to NaCl treatment was noticed. Salt tolerant varieties also produced increased level of ferulic acid and vanillic acid. In the salt sensitive varieties, cinnamic acid derivatives, 4-hydroxycinnamic acid (in Sujala) and 4-hydroxybenzoic acid (in MTU 7029), were elevated in the leaves. So increased production of the 2 signaling molecules serotonin and gentisic acid may be considered as 2 important biomarker compounds produced in tolerant varieties contributing toward NaCl tolerance.

Methanogens and Martian natural resources: Investigations regarding the possibility of biogenic methane on Mars

NASA Astrophysics Data System (ADS)

Chastain, Brendon Kelly

Archaeal methanogens were suggested as terrestrial models of possible subsurface martian microbial life prior to the actual detection of methane in Mars' atmosphere. This idea gained even more interest after the methane on Mars was observed. However, the amount of methane detected was very small, and release of methane was localized and episodic. This led some scientists to doubt that an active or ancient biosphere could be the source of the methane. Moreover, even extremophilic methanogens have not been shown to metabolize in conditions exactly analogous to those known to be available on Mars. The following chapters present a realistic and viable mechanism that allows a large or ancient biosphere to be the original source of the observed methane, and they detail experimental work that was done in order to systematically investigate nutritional and conditional variables related to those that might be available in the martian subsurface. The results of the experimental work indicate that some components of Mars' regolith can support methanogenic metabolism without being detrimental to the organisms, and that certain known components of Mars' regolith can promote periods of methanogenic dormancy without being lethal to the methanogens. The results of the experimental studies also show that material known to exist at and near Mars' surface has the potential to supply electrons for biological methanogenesis and that methanogenic metabolism can occur even when artificial media, buffers, and reductants are omitted in order to create more Mars-relevant conditions. These findings may have implications regarding the viability of methanogenic organisms as a source of the observed methane and should assist future efforts to study methanogenic metabolism in conditions exactly analogous to those available in niches on Mars.

Metabolic pathways regulated by abscisic acid, salicylic acid and γ-aminobutyric acid in association with improved drought tolerance in creeping bentgrass (Agrostis stolonifera).

PubMed

Li, Zhou; Yu, Jingjin; Peng, Yan; Huang, Bingru

2017-01-01

Abscisic acid (ABA), salicylic acid (SA) and γ-aminobutyric acid (GABA) are known to play roles in regulating plant stress responses. This study was conducted to determine metabolites and associated pathways regulated by ABA, SA and GABA that could contribute to drought tolerance in creeping bentgrass (Agrostis stolonifera). Plants were foliar sprayed with ABA (5 μM), GABA (0.5 mM) and SA (10 μM) or water (untreated control) prior to 25 days drought stress in controlled growth chambers. Application of ABA, GABA or SA had similar positive effects on alleviating drought damages, as manifested by the maintenance of lower electrolyte leakage and greater relative water content in leaves of treated plants relative to the untreated control. Metabolic profiling showed that ABA, GABA and SA induced differential metabolic changes under drought stress. ABA mainly promoted the accumulation of organic acids associated with tricarboxylic acid cycle (aconitic acid, succinic acid, lactic acid and malic acid). SA strongly stimulated the accumulation of amino acids (proline, serine, threonine and alanine) and carbohydrates (glucose, mannose, fructose and cellobiose). GABA enhanced the accumulation of amino acids (GABA, glycine, valine, proline, 5-oxoproline, serine, threonine, aspartic acid and glutamic acid) and organic acids (malic acid, lactic acid, gluconic acid, malonic acid and ribonic acid). The enhanced drought tolerance could be mainly due to the enhanced respiration metabolism by ABA, amino acids and carbohydrates involved in osmotic adjustment (OA) and energy metabolism by SA, and amino acid metabolism related to OA and stress-defense secondary metabolism by GABA. © 2016 Scandinavian Plant Physiology Society.

Roles of Organic Acid Anion Secretion in Aluminium Tolerance of Higher Plants

PubMed Central

Yang, Lin-Tong; Qi, Yi-Ping; Jiang, Huan-Xin; Chen, Li-Song

2013-01-01

Approximately 30% of the world's total land area and over 50% of the world's potential arable lands are acidic. Furthermore, the acidity of the soils is gradually increasing as a result of the environmental problems including some farming practices and acid rain. At mildly acidic or neutral soils, aluminium(Al) occurs primarily as insoluble deposits and is essentially biologically inactive. However, in many acidic soils throughout the tropics and subtropics, Al toxicity is a major factor limiting crop productivity. The Al-induced secretion of organic acid (OA) anions, mainly citrate, oxalate, and malate, from roots is the best documented mechanism of Al tolerance in higher plants. Increasing evidence shows that the Al-induced secretion of OA anions may be related to the following several factors, including (a) anion channels or transporters, (b) internal concentrations of OA anions in plant tissues, (d) temperature, (e) root plasma membrane (PM) H+-ATPase, (f) magnesium (Mg), and (e) phosphorus (P). Genetically modified plants and cells with higher Al tolerance by overexpressing genes for the secretion and the biosynthesis of OA anions have been obtained. In addition, some aspects needed to be further studied are also discussed. PMID:23509687

Safety, tolerability, and cerebrospinal fluid penetration of ursodeoxycholic Acid in patients with amyotrophic lateral sclerosis.

PubMed

Parry, Gareth J; Rodrigues, Cecilia M P; Aranha, Marcia M; Hilbert, Sarah J; Davey, Cynthia; Kelkar, Praful; Low, Walter C; Steer, Clifford J

2010-01-01

Amyotrophic lateral sclerosis is a progressive degenerative disease, which typically leads to death in 3 to 5 years. Neuronal cell death offers a potential target for therapeutic intervention. Ursodeoxycholic acid is a cytoprotective, endogenous bile acid that has been shown to be neuroprotective in experimental Huntington and Alzheimer diseases, retinal degeneration, and ischemic and hemorrhagic stroke. The objective of this research was to study the safety and the tolerability of ursodeoxycholic acid in amyotrophic lateral sclerosis and document effective and dose-dependent cerebrospinal fluid penetration. Eighteen patients were randomly assigned to receive ursodeoxycholic acid at doses of 15, 30, and 50 mg/kg of body weight per day. Serum and cerebrospinal fluid were obtained for analysis after 4 weeks of treatment. Treatment-emergent clinical and laboratory events were monitored weekly. Our data indicated that ursodeoxycholic acid is well tolerated by all subjects at all doses. We also showed that ursodeoxycholic acid is well absorbed after oral administration and crosses the blood-brain barrier in a dose-dependent manner. These results show excellent safety and tolerability of ursodeoxycholic acid. The drug penetrates the cerebrospinal fluid in a dose-dependent manner. A large, placebo-controlled clinical trial is needed to assess the efficacy of ursodeoxycholic acid in treating amyotrophic lateral sclerosis.

Whey protein isolate improves acid and bile tolerances of Streptococcus thermophilus ST-M5 and Lactobacillus delbrueckii ssp. bulgaricus LB-12.

PubMed

Vargas, Luis A; Olson, Douglas W; Aryana, Kayanush J

2015-04-01

Acid tolerance and bile tolerance are important probiotic characteristics. Whey proteins contain branched-chain amino acids, which play a role in muscle building and are popular among athletes. Increasing emphasis is being placed on diets containing less carbohydrate, less fat, and more protein. The effect of incremental additions of whey protein isolate (WPI) on probiotic characteristics of pure cultures is not known. The objective of this study was to determine the influence of added WPI on acid tolerance and bile tolerance of pure cultures of Streptococcus thermophilus ST-M5 and Lactobacillus bulgaricus LB-12. The WPI was used at 0 (control), 1, 2 and 3% (wt/vol). Assessment of acid tolerance was conducted on pure cultures at 30-min intervals for 2h of acid exposure and bile tolerance at 1-h intervals for 5h of bile exposure. Use of 1, 2, and 3% WPI improved acid tolerance of Strep. thermophilus ST-M5 and Lb. bulgaricus LB-12. The highest counts for acid tolerance of Strep. thermophilus ST-M5 and Lb. bulgaricus LB-12 were obtained when 3% WPI was used. Use of 2 and 3% WPI improved bile tolerance of Strep. thermophilus ST-M5 and Lb. bulgaricus LB-12 over 5h of bile exposure. The use of WPI is recommended to improve acid and bile tolerance of the yogurt culture bacteria Strep. thermophilus ST-M5 and Lb. bulgaricus LB-12. Copyright © 2015 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Engineering Clostridium beijerinckii with the Cbei_4693 gene knockout for enhanced ferulic acid tolerance.

PubMed

Liu, Jun; Guo, Ting; Shen, Xiaoning; Xu, Jiahui; Wang, Junzhi; Wang, Yanyan; Liu, Dong; Niu, Huanqing; Liang, Lei; Ying, Hanjie

2016-07-10

A mutant strain of Clostridium beijerinckii NCIMB 8052, C. beijerinckii M11, which exhibited ferulic acid tolerance up to 0.9g/L, was generated using atmospheric pressure glow discharge and high-throughput screening. Comparative genomic analysis revealed that this strain harbored a mutation of the Cbei_4693 gene, which encodes a hypothetical protein suspected to be an NADPH-dependent FMN reductase. After disrupting the Cbei_4693 gene in C. beijerinckii NCIMB 8052 using the ClosTron group II intron-based gene inactivation system, we obtained the Cbei_4693 gene inactivated mutant strain, C. beijerinckii 4693::int. Compared with C. beijerinckii NCIMB 8052, 6.23g/L of butanol was produced in P2 medium containing 0.5g/L of ferulic acid by 4693::int, and the ferulic acid tolerance was also significantly increased up to 0.8g/L. These data showed, for the first time, that the Cbei_4693 gene plays an important role in regulating ferulic acid tolerance in ABE fermentation by C. beijerinckii. Copyright © 2016 Elsevier B.V. All rights reserved.

Low Temperature-Induced Decrease in trans-Delta-Hexadecenoic Acid Content Is Correlated with Freezing Tolerance in Cereals.

PubMed

Huner, N P; Williams, J P; Maissan, E E; Myscich, E G; Krol, M; Laroche, A; Singh, J

1989-01-01

The effect of growth at 5 degrees C on the trans-Delta(3)-hexadecenoic acid content of phosphatidyl(d)glycerol was examined in a total of eight cultivars of rye (Secale cereale L.) and what (Triticum aestivum L.) of varying freezing tolerance. In these monocots, low temperature growth caused decreases in the trans-Delta(3)-hexadecenoic acid content of between 0 and 74% with concomitant increases in the palmitic acid content of phosphatidyl(d)glycerol. These trends were observed for whole leaf extracts as well as isolated thylakoids. The low growth temperature-induced decrease in the trans-Delta(3)-hexadecenoic acid content was shown to be a linear function (r(2) = 0.954) of freezing tolerance in these cultivars. Of the six cold tolerant dicotyledonous species examined, only Brassica and Arabidopsis thaliana L. cv Columbia exhibited a 42% and 65% decrease, respectively, in trans-Delta(3)-hexadecenoic acid content. Thus, the relationship between the change in trans-Delta(3)-hexadecenoic acid content of phosphatidyl(d)glycerol and freezing tolerance cannot be considered a general one for all cold tolerant plant species. However, species which exhibited a low growth temperature-induced decrease in trans-Delta(3)-hexadecenoic acid also exhibited a concomitant shift in the in vitro organization of the light harvesting complex II from a predominantly oligomeric form to the monomeric form. We conclude that the proposed role of phosphatidyl(d)glycerol in modulating the organization of light harvesting complex II as a function of growth temperature manifests itself to varying degrees in different plant species. A possible physiological role for this phenomenon with respect to low temperature acclimation and freezing tolerance in cereals is discussed.

Influence of ethanol adaptation on Salmonella enterica serovar Enteritidis survival in acidic environments and expression of acid tolerance-related genes.

PubMed

He, Shoukui; Cui, Yan; Qin, Xiaojie; Zhang, Fen; Shi, Chunlei; Paoli, George C; Shi, Xianming

2018-06-01

Cross-protection to environmental stresses by ethanol adaptation in Salmonella poses a great threat to food safety because it can undermine food processing interventions. The ability of Salmonella enterica serovar Enteritidis (S. Enteritidis) to develop acid resistance following ethanol adaptation (5% ethanol for 1 h) was evaluated in this study. Ethanol-adapted S. Enteritidis mounted cross-tolerance to malic acid (a two-fold increase in minimum bactericidal concentration), but not to acetic, ascorbic, lactic, citric and hydrochloric acids. The population of S. Enteritidis in orange juice (pH 3.77) over a 48-h period was not significantly (p > 0.05) influenced by ethanol adaptation. However, an increased survival by 0.09-1.02 log CFU/ml was noted with ethanol-adapted cells of S. Enteritidis compared to non-adapted cells in apple juice (pH 3.57) stored at 25 °C (p < 0.05), but not at 4 °C. RT-qPCR revealed upregulation of two acid tolerance-related genes, rpoS (encoding σ S ) and SEN1564A (encoding an acid shock protein), following ethanol adaptation. The relative expression level of the acid resistance gene hdeB did not change. The resistance phenotypes and transcriptional profiles of S. Enteritidis suggest some involvement of rpoS and SEN1564A in the ethanol-induced acid tolerance mechanism. Copyright © 2017. Published by Elsevier Ltd.

Methanogenic archaea and sulfate reducing bacteria co-cultured on acetate: teamwork or coexistence?

PubMed

Ozuolmez, Derya; Na, Hyunsoo; Lever, Mark A; Kjeldsen, Kasper U; Jørgensen, Bo B; Plugge, Caroline M

2015-01-01

Acetate is a major product of fermentation processes and an important substrate for sulfate reducing bacteria and methanogenic archaea. Most studies on acetate catabolism by sulfate reducers and methanogens have used pure cultures. Less is known about acetate conversion by mixed pure cultures and the interactions between both groups. We tested interspecies hydrogen transfer and coexistence between marine methanogens and sulfate reducers using mixed pure cultures of two types of microorganisms. First, Desulfovibrio vulgaris subsp. vulgaris (DSM 1744), a hydrogenotrophic sulfate reducer, was cocultured together with the obligate aceticlastic methanogen Methanosaeta concilii using acetate as carbon and energy source. Next, Methanococcus maripaludis S2, an obligate H2- and formate-utilizing methanogen, was used as a partner organism to M. concilii in the presence of acetate. Finally, we performed a coexistence experiment between M. concilii and an acetotrophic sulfate reducer Desulfobacter latus AcSR2. Our results showed that D. vulgaris was able to reduce sulfate and grow from hydrogen leaked by M. concilii. In the other coculture, M. maripaludis was sustained by hydrogen leaked by M. concilii as revealed by qPCR. The growth of the two aceticlastic microbes indicated co-existence rather than competition. Altogether, our results indicate that H2 leaking from M. concilii could be used by efficient H2-scavengers. This metabolic trait, revealed from coculture studies, brings new insight to the metabolic flexibility of methanogens and sulfate reducers residing in marine environments in response to changing environmental conditions and community compositions. Using dedicated physiological studies we were able to unravel the occurrence of less obvious interactions between marine methanogens and sulfate-reducing bacteria.

Methanogenic archaea and sulfate reducing bacteria co-cultured on acetate: teamwork or coexistence?

PubMed Central

Ozuolmez, Derya; Na, Hyunsoo; Lever, Mark A.; Kjeldsen, Kasper U.; Jørgensen, Bo B.; Plugge, Caroline M.

2015-01-01

Acetate is a major product of fermentation processes and an important substrate for sulfate reducing bacteria and methanogenic archaea. Most studies on acetate catabolism by sulfate reducers and methanogens have used pure cultures. Less is known about acetate conversion by mixed pure cultures and the interactions between both groups. We tested interspecies hydrogen transfer and coexistence between marine methanogens and sulfate reducers using mixed pure cultures of two types of microorganisms. First, Desulfovibrio vulgaris subsp. vulgaris (DSM 1744), a hydrogenotrophic sulfate reducer, was cocultured together with the obligate aceticlastic methanogen Methanosaeta concilii using acetate as carbon and energy source. Next, Methanococcus maripaludis S2, an obligate H2- and formate-utilizing methanogen, was used as a partner organism to M. concilii in the presence of acetate. Finally, we performed a coexistence experiment between M. concilii and an acetotrophic sulfate reducer Desulfobacter latus AcSR2. Our results showed that D. vulgaris was able to reduce sulfate and grow from hydrogen leaked by M. concilii. In the other coculture, M. maripaludis was sustained by hydrogen leaked by M. concilii as revealed by qPCR. The growth of the two aceticlastic microbes indicated co-existence rather than competition. Altogether, our results indicate that H2 leaking from M. concilii could be used by efficient H2-scavengers. This metabolic trait, revealed from coculture studies, brings new insight to the metabolic flexibility of methanogens and sulfate reducers residing in marine environments in response to changing environmental conditions and community compositions. Using dedicated physiological studies we were able to unravel the occurrence of less obvious interactions between marine methanogens and sulfate-reducing bacteria. PMID:26074892

Avocado and soybean extracts as active principles in the treatment of mild-to-moderate vulvar lichen sclerosus: results of efficacy and tolerability.

PubMed

Borghi, A; Corazza, M; Minghetti, S; Toni, G; Virgili, A

2015-06-01

Limited evidence is available on the effectiveness of treatments alternative to corticosteroids for vulvar lichen sclerosus (VLS). The present study aimed to assess the efficacy and tolerability of avocado and soybean extracts (ASE) as active principles of both a topical product and a nutritional supplement in the treatment of active mild-to-moderate VLS. Twenty-three patients were enrolled. Treatment consisted of a topical product containing ASE and other lenitive and anti-oxidant principles administered twice daily for 24 weeks, in association with a dietary supplement containing ASE, vitamin E and para-aminobenzoic acid for the first 12 weeks. The primary efficacy endpoint was the rate of patients achieving an improvement from baseline in global subjective score (GSS) and global objective score (GOS) of ≥ 75%. Secondary efficacy endpoint was the rate of patients achieving GSS50 and GOS50. Tertiary efficacy endpoint was the mean reduction in subjective and objective scores throughout the treatment. By the end of the 24-week treatment, 12 (70.5% of symptomatic patients) and 13 patients (72.2%) achieved an improvement of at least 75% in subjective and objective global scores, respectively; 100% and 88.9% reached GSS50 and GOS50, respectively. Mean symptom and sign scores decreased significantly after treatment. The treatment was well tolerated. Our results provide evidence that the topical and dietary supplements used in the study, which contain active principles exerting anti-inflammatory, anti-fibrotic, emollient and lenitive actions, are effective alternatives in the treatment of symptoms and signs of mild-to-moderate VLS. © 2014 European Academy of Dermatology and Venereology.

Community structure of rare methanogenic archaea: insight from a single functional group

PubMed Central

Winkel, Matthias; Wagner, Dirk

2017-01-01

Abstract The rare biosphere, the low abundant microbial populations, is suggested to be a conserved way of microbial life. Here we conducted a molecular survey of rare methanogenic archaea in the environment targeting the mcrA gene in order to test if general concepts associated with the structure of the rare bacterial biosphere also apply to single functional groups. Similar to what is known about rare bacterial communities, the contribution of rare methanogens to the alpha diversity is much larger than to Bray-Curtis measures. Moreover, a similar core group of methanogens harbored by the abundant and rare communities suggests similar sources and environmental controls of both groups. Among the communities of different levels of rarity, the conditionally rare methanogenic taxa largely account for the overall community dynamics of the rare biosphere and likely enter the dominant community under favorable environmental conditions. In addition, we observed a positive correlation between the alpha diversity and the production of methane when the rare taxa were taken into account. This supports the concept that increasing microbial biodiversity enhances ecological function. The composition and environmental associations of the rare methanogenic biosphere allow us to conclude that rarity is a conserved way also for single functional groups. PMID:29029047

Butanol production by a Clostridium beijerinckii mutant with high ferulic acid tolerance.

PubMed

Liu, Jun; Guo, Ting; Wang, Dong; Xu, Jiahui; Ying, Hanjie

2016-09-01

A mutant strain of Clostridium beijerinckii, with high tolerance to ferulic acid, was generated using atmospheric pressure glow discharge and high-throughput screening of C. beijerinckii NCIMB 8052. The mutant strain M11 produced 7.24 g/L of butanol when grown in P2 medium containing 30 g/L of glucose and 0.5 g/L of ferulic acid, which is comparable to the production from non-ferulic acid cultures (8.11 g/L of butanol). When 0.8 g/L of ferulic acid was introduced into the P2 medium, C. beijerinckii M11 grew well and produced 4.91 g/L of butanol. Both cell growth and butanol production of C. beijerinckii M11 were seriously inhibited when 0.9 g/L of ferulic acid was added into the P2 medium. Furthermore, C. beijerinckii M11 could produce 6.13 g/L of butanol using non-detoxified hemicellulosic hydrolysate from diluted sulfuric acid-treated corn fiber (SAHHC) as the carbon source. These results demonstrate that C. beijerinckii M11 has a high ferulic acid tolerance and is able to use non-detoxified SAHHC for butanol production. © 2015 International Union of Biochemistry and Molecular Biology, Inc.

An ancient divergence among the bacteria. [methanogenic phylogeny

NASA Technical Reports Server (NTRS)

Balch, W. E.; Magrum, L. J.; Fox, G. E.; Wolfe, R. S.; Woese, C. R.

1977-01-01

The 16S ribosomal RNZs from two species of met methanogenic bacteria, the mesophile Methanobacterium ruminantium and the thermophile Methanobacterium thermoautotrophicum, have been characterized in terms of the oligonucleotides produced by digestion with T1 ribonuclease. These two organisms are found to be sufficiently related that they can be considered members of the same genus or family. However, they bear only slight resemblance to 'typical' Procaryotic genera; such as Escherichia, Bacillus and Anacystis. The divergence of the methanogenic bacteria from other bacteria may be the most ancient phylogenetic event yet detected - antedating considerably the divergence of the blue green algal line for example, from the main bacterial line.

Physico-chemical characteristics and methanogen communities in swine and dairy manure storage tanks: spatio-temporal variations and impact on methanogenic activity.

PubMed

Barret, Maialen; Gagnon, Nathalie; Topp, Edward; Masse, Lucie; Massé, Daniel I; Talbot, Guylaine

2013-02-01

Greenhouse gas emissions represent a major environmental problem associated with the management of manure from the livestock industry. Methane is the primary GHG emitted during manure outdoor storage. In this paper, the variability of two swine and two dairy manure storage tanks was surveyed, in terms of physico-chemical and microbiological parameters. The impact of the inter-tank and spatio-temporal variations of these parameters on the methanogenic activity of manure was ascertained. A Partial Least Square regression was carried out, which demonstrated that physico-chemical as well as microbiological parameters had a major influence on the methanogenic activity. Among the 19 parameters included in the regression, the concentrations of VFAs had the strongest negative influence on the methane emission rate of manure, resulting from their well-known inhibitory effect. The relative abundance of two amplicons in archaeal fingerprints was found to positively influence the methanogenic activity, suggesting that Methanoculleus spp. and possibly Methanosarcina spp. are major contributors to methanogenesis in storage tanks. This work gave insights into the mechanisms, which drive methanogenesis in swine and dairy manure storage tanks. Crown Copyright © 2012. Published by Elsevier Ltd. All rights reserved.

Salicylic acid peel incorporating triethyl citrate and ethyl linoleate in the treatment of moderate acne: a new therapeutic approach.

PubMed

Raone, Beatrice; Veraldi, Stefano; Raboni, Roberta; Ardigò, Marco; Patrizi, Annalisa; Micali, Giuseppe

2013-08-01

Acne affects many adolescents. Conventional therapy often results in side effects and poor adherence, and the treatment does not consider the psychological effect of acne on patients, which is comparable with that of disabling diseases. To evaluate the efficacy and tolerability of a peel (30% salicylic acid, triethyl citrate and ethyl linoleate) combined with a home therapy with three topical agents (triethyl citrate, ethyl linoleate and salicylic acid 0.5% cream, lotion) in moderate acne of the face. Prospective, observational, multicenter, open-label, postmarketing, phase IV study. Patients were assessed by comparing Global Acne Grading System (GAGS) score and total lesion count from 15 days before the first peel (T-15 ), after four salicylic peels (every 10 ± 2 days (T0 , T10 , T20 , T30 ), and 20 days after of the end of the study (T50 ). This treatment was associated to a home therapy. Fifty-three patients completed the study. The average GAGS score fell 49% between T-15 and T50 (p < .001). No patient withdrew for adverse events. This therapy was effective and well-tolerated in all cases. Chemo-exfoliation sessions ensured the continuous monitoring of clinical results and improved patient quality of life. © 2013 by the American Society for Dermatologic Surgery, Inc. Published by Wiley Periodicals, Inc.

Comparative Evaluation of Efficacy and Tolerability of Glycolic Acid, Salicylic Mandelic Acid, and Phytic Acid Combination Peels in Melasma.

PubMed

Sarkar, Rashmi; Garg, Vijay; Bansal, Shivani; Sethi, Sumit; Gupta, Chitra

2016-03-01

Melasma is acquired symmetric hypermelanosis characterized by light-to-deep brown pigmentation over cheeks, forehead, upper lip, and nose. Treatment of this condition is difficult and associated with high recurrence rates. Chemical peels have become a popular modality in the treatment of melasma. To compare the therapeutic efficacy and tolerability of glycolic acid (35%) versus salicylic-mandelic (SM) acid (20% salicylic/10% mandelic acid) versus phytic combination peels in Indian patients with melasma. Ninety patients diagnosed with melasma were randomly assigned into 3 groups of 30 patients each. Group A received glycolic acid (GA-35%) peel, Group B received SM acid, and Group C received phytic combination peels. Each group was primed with 4% hydroquinone and 0.05% tretinoin cream for 4 weeks before treatment. Chemical peeling was done after every 14 days in all groups until 12 weeks. Clinical evaluation using melasma area and severity index (MASI) score and photography was recorded at every visit and follow-up was done until 20 weeks. There was a decrease in MASI score in all 3 groups but it was statistically significantly lower in Group A than Group C (p = .00), and it was also statistically significantly lower in Group B than Group C (p = .00) but there was no statistically significant difference between Groups A and B (p = .876). Objective response to treatment evaluated by reduction in MASI scoring after 12 weeks was 62.36% reduction in GA group, 60.98% reduction in SM group, and 44.71% in phytic acid group. It is concluded that GA (35%) and SM acid peels are both equally efficacious and a safe treatment modality for melasma in Indian skin, and are more effective than phytic acid peels. Salicylic-mandelic peels are better tolerated and more suitable for Indian skin.

Clinical tolerance and efficacy of capryloyl salicylic acid peel compared to a glycolic acid peel in subjects with fine lines/wrinkles and hyperpigmented skin.

PubMed

Oresajo, Christian; Yatskayer, Margarita; Hansenne, Isabelle

2008-12-01

Several chemical agents are currently used to perform superficial peels of the face to reduce facial hyperpigmentation and fine lines/wrinkles. Some of the most commonly used agents are alpha hydroxyl acids, such as glycolic acid (GA), or beta hydroxy acid, such as salicylic acid. This study aims to compare the efficacy of GA to that of a novel derivative of salicylic acid, capryloyl salicylic acid (LHA). In a split-face study, 50 female volunteers between the ages of 35 and 60 years with mild to moderate facial hyperpigmentation and fine lines/wrinkles were randomized and LHA or GA peel was applied to one side of the face. Increasing peel concentrations were applied (5-10% LHA or 20-50% GA) based on the tolerance level of the subjects and clinical observations of an expert dermatologist for 12 weeks at biweekly intervals. Of the 44 volunteers who completed the study, at 12 weeks 41% of LHA-treated and 30% of GA-treated subjects demonstrated significant reduction of fine lines/wrinkles compared to baseline. Forty-six percent of LHA-treated subjects and 34% of GA-treated subjects showed significant reduction of hyperpigmentation compared to baseline. LHA treatment was better than GA peels, although there were no statistically significant differences between the two groups. Five percent to 10% of LHA peel is generally safe and as effective as 20-50% GA peel in reducing facial hyperpigmentation and fine lines/wrinkles.

Photoenhanced anaerobic digestion of organic acids

DOEpatents

Weaver, Paul F.

1990-01-01

A process is described for rapid conversion of organic acids and alcohols anaerobic digesters into hydrogen and carbon dioxide, the optimal precursor substrates for production of methane. The process includes addition of photosynthetic bacteria to the digester and exposure of the bacteria to radiant energy (e.g., solar energy). The process also increases the pH stability of the digester to prevent failure of the digester. Preferred substrates for photosynthetic bacteria are the organic acid and alcohol waste products of fermentative bacteria. In mixed culture with methanogenic bacteria or in defined co-culture with non-aceticlastic methanogenic bacteria, photosynthetic bacteria are capable of facilitating the conversion or organic acids and alcohols into methane with low levels of light energy input.

Drug resistance marker-aided genome shuffling to improve acetic acid tolerance in Saccharomyces cerevisiae.

PubMed

Zheng, Dao-Qiong; Wu, Xue-Chang; Wang, Pin-Mei; Chi, Xiao-Qin; Tao, Xiang-Lin; Li, Ping; Jiang, Xin-Hang; Zhao, Yu-Hua

2011-03-01

Acetic acid existing in a culture medium is one of the most limiting constraints in yeast growth and viability during ethanol fermentation. To improve acetic acid tolerance in Saccharomyces cerevisiae strains, a drug resistance marker-aided genome shuffling approach with higher screen efficiency of shuffled mutants was developed in this work. Through two rounds of genome shuffling of ultraviolet mutants derived from the original strain 308, we obtained a shuffled strain YZ2, which shows significantly faster growth and higher cell viability under acetic acid stress. Ethanol production of YZ2 (within 60 h) was 21.6% higher than that of 308 when 0.5% (v/v) acetic acid was added to fermentation medium. Membrane integrity, higher in vivo activity of the H+-ATPase, and lower oxidative damage after acetic acid treatment are the possible reasons for the acetic acid-tolerance phenotype of YZ2. These results indicated that this novel genome shuffling approach is powerful to rapidly improve the complex traits of industrial yeast strains.

High-Performance Biogas Upgrading Using a Biotrickling Filter and Hydrogenotrophic Methanogens.

PubMed

Dupnock, Trisha L; Deshusses, Marc A

2017-10-01

This research reports the development of a biotrickling filter (BTF) to upgrade biogas, which is achieved by adding H 2 to reduce CO 2 . H 2 and CO 2 (80:20% vol.) were fed to a bench-scale BTF packed with polyurethane foam (PUF) and inoculated with hydrogenotrophic methanogens. Maximum CH 4 production rates recorded were as high as 38 m 3 CH4  m -3 reactor  day -1 , which is 5-30 times faster than earlier reports with other kinds of bioreactors. The high rates were attributed to the efficient mass transfer and high density of methanogens in the BTF. The removal efficiencies for H 2 and CO 2 were 83 and 96%, respectively. 5-Cyano-2,3-ditolyl tetrazolium chloride/DAPI staining revealed that 67% of cells were alive near the gas entrance port, while only 8.3% were alive at the exit. Furthermore, DNA sequencing showed that only 27% of the biomass was composed of Euryarchaeota, the phylum which includes methanogens. These two observations suggest that optimizing the methanogen density and activity could possibly reach even higher biogas upgrading rates.

Rumen microbial diversity in Svalbard reindeer, with particular emphasis on methanogenic archaea.

PubMed

Sundset, Monica A; Edwards, Joan E; Cheng, Yan Fen; Senosiain, Roberto S; Fraile, Maria N; Northwood, Korinne S; Praesteng, Kirsti E; Glad, Trine; Mathiesen, Svein D; Wright, André-Denis G

2009-12-01

Ruminal methanogens, bacteria and ciliate protozoa of Svalbard reindeer grazing natural pastures in October (late fall) and April (late winter) were investigated using molecular-based approaches. The appetite of the Svalbard reindeer peaks in August (summer) and is at its lowest in March (winter). Microbial numbers, quantified by real-time PCR, did not change significantly between October and April, when food intakes are at similar levels, although the numbers of methanogens tended to be higher in October (P=0.074), and ciliate numbers tended to be higher in April (P=0.055). Similarly, no change was detected in the bacterial and protozoal population composition by rRNA gene-based denaturing gradient gel electrophoresis analysis. Dominant methanogens were identified using a 16S rRNA gene library (97 clones) prepared from pooled PCR products from reindeer on October pasture (n=5). Eleven of the 22 distinct operational taxonomic units (OTUs) generated exhibited a high degree of sequence similarity to methanogens affiliated with Methanobacteriales (eight OTUs), Methanomicrobiales (one OTU) and Methanosarcinales (two OTUs). The remaining 11 OTUs (53% of the clones) were associated with a cluster of uncultivated ruminal archaea. This study has provided important insights into the rumen microbiome of a high-arctic herbivorous animal living under harsh nutritional conditions, and evidence suggesting that host type affects the population size of ruminal methanogens.

Assessing the Ecophysiology of Methanogens in the Context of Recent Astrobiological and Planetological Studies

PubMed Central

Taubner, Ruth-Sophie; Schleper, Christa; Firneis, Maria G.; Rittmann, Simon K.-M. R.

2015-01-01

Among all known microbes capable of thriving under extreme and, therefore, potentially extraterrestrial environmental conditions, methanogens from the domain Archaea are intriguing organisms. This is due to their broad metabolic versatility, enormous diversity, and ability to grow under extreme environmental conditions. Several studies revealed that growth conditions of methanogens are compatible with environmental conditions on extraterrestrial bodies throughout the Solar System. Hence, life in the Solar System might not be limited to the classical habitable zone. In this contribution we assess the main ecophysiological characteristics of methanogens and compare these to the environmental conditions of putative habitats in the Solar System, in particular Mars and icy moons. Eventually, we give an outlook on the feasibility and the necessity of future astrobiological studies concerning methanogens. PMID:26703739

Methanogenic food web in the gut contents of methane-emitting earthworm Eudrilus eugeniae from Brazil

PubMed Central

Schulz, Kristin; Hunger, Sindy; Brown, George G; Tsai, Siu M; Cerri, Carlos C; Conrad, Ralf; Drake, Harold L

2015-01-01

The anoxic saccharide-rich conditions of the earthworm gut provide an ideal transient habitat for ingested microbes capable of anaerobiosis. It was recently discovered that the earthworm Eudrilus eugeniae from Brazil can emit methane (CH4) and that ingested methanogens might be associated with this emission. The objective of this study was to resolve trophic interactions of bacteria and methanogens in the methanogenic food web in the gut contents of E. eugeniae. RNA-based stable isotope probing of bacterial 16S rRNA as well as mcrA and mrtA (the alpha subunit of methyl-CoM reductase and its isoenzyme, respectively) of methanogens was performed with [13C]-glucose as a model saccharide in the gut contents. Concomitant fermentations were augmented by the rapid consumption of glucose, yielding numerous products, including molecular hydrogen (H2), carbon dioxide (CO2), formate, acetate, ethanol, lactate, succinate and propionate. Aeromonadaceae-affiliated facultative aerobes, and obligate anaerobes affiliated to Lachnospiraceae, Veillonellaceae and Ruminococcaceae were associated with the diverse fermentations. Methanogenesis was ongoing during incubations, and 13C-labeling of CH4 verified that supplemental [13C]-glucose derived carbon was dissimilated to CH4. Hydrogenotrophic methanogens affiliated with Methanobacteriaceae and Methanoregulaceae were linked to methanogenesis, and acetogens related to Peptostreptoccocaceae were likewise found to be participants in the methanogenic food web. H2 rather than acetate stimulated methanogenesis in the methanogenic gut content enrichments, and acetogens appeared to dissimilate supplemental H2 to acetate in methanogenic enrichments. These findings provide insight on the processes and associated taxa potentially linked to methanogenesis and the turnover of organic carbon in the alimentary canal of methane-emitting E. eugeniae. PMID:25615437

Habituation of enterotoxigenic Staphylococcus aureus to Origanum vulgare L. essential oil does not induce direct-tolerance and cross-tolerance to salts and organic acids

PubMed Central

Tavares, Adassa Gama; do Monte, Daniel Farias Marinho; Albuquerque, Allan dos Reis; Sampaio, Fábio Correia; Magnani, Marciane; de Siqueira, José Pinto; de Souza, Evandro Leite

2015-01-01

Enterotoxigenic Staphylococcus aureus strains that were isolated from foods were investigated for their ability to develop direct-tolerance and cross-tolerance to sodium chloride (NaCl), potassium chloride (KCl), lactic acid (LA) and acetic acid (AA) after habituation in sublethal amounts (1/2 of the minimum inhibitory concentration - 1/2 MIC and 1/4 of the minimum inhibitory concentration - 1/4 MIC) of Origanum vulgare L. essential oil (OVEO). The habituation of S. aureus to 1/2 MIC and 1/4 MIC of OVEO did not induce direct-tolerance or cross-tolerance in the tested strains, as assessed by modulation of MIC values. Otherwise, exposing the strains to OVEO at sublethal concentrations maintained or increased the sensitivity of the cells to the tested stressing agents because the MIC values of OVEO, NaCl, KCl, LA and AA against the cells that were previously habituated to OVEO remained the same or decreased when compared with non-habituated cells. These data indicate that OVEO does not have an inductive effect on the acquisition of direct-tolerance or cross-tolerance in the tested enterotoxigenic strains of S. aureus to antimicrobial agents that are typically used in food preservation. PMID:26413067

Toxicity and tolerance of aluminum in plants: tailoring plants to suit to acid soils.

PubMed

Sade, Hemalatha; Meriga, Balaji; Surapu, Varalakshmi; Gadi, Jogeswar; Sunita, M S L; Suravajhala, Prashanth; Kavi Kishor, P B

2016-04-01

Aluminum (Al) stress is one of the serious limiting factors in plant productivity in acidic soils, which constitute about 50 % of the world's potentially arable lands and causes anywhere between 25 and 80 % of yield losses depending upon the species. The mechanism of Al toxicity and tolerance has been examined in plants, which is vital for crop improvement and enhanced food production in the future. Two mechanisms that facilitate Al tolerance in plants are Al exclusion from the roots and the ability to tolerate Al in the symplast or both. Although efforts have been made to unravel Al-resistant factors, many aspects remain unclear. Certain gene families such as MATE, ALMT, ASR, and ABC transporters have been implicated in some plants for resistance to Al which would enhance the opportunities for creating crop plants suitable to grow in acidic soils. Though QTLs have been identified related to Al-tolerance, no crop plant that is tolerant to Al has been evolved so far using breeding or molecular approaches. The remarkable changes that plants experience at the physiological, biochemical and molecular level under Al stress, the vast array of genes involved in Al toxicity-tolerance, the underlying signaling events and the holistic image of the molecular regulation, and the possibility of creating transgenics for Al tolerance are discussed in this review.

Survival of methanogens during desiccation: implications for life on Mars.

PubMed

Kendrick, Michael G; Kral, Timothy A

2006-08-01

The relatively recent discoveries that liquid water likely existed on the surface of past Mars and that methane currently exists in the martian atmosphere have fueled the possibility of extant or extinct life on Mars. One possible explanation for the existence of the methane would be the presence of methanogens in the subsurface. Methanogens are microorganisms in the domain Archaea that can metabolize molecular hydrogen as an energy source and carbon dioxide as a carbon source and produce methane. One factor of importance is the arid nature of Mars, at least at the surface. If one is to assume that life exists below the surface, then based on the only example of life that we know, liquid water must be present. Realistically, however, that liquid water may be seasonal just as it is at some locations on our home planet. Here we report on research designed to determine how long certain species of methanogens can survive desiccation on a Mars soil simulant, JSC Mars-1. Methanogenic cells were grown on JSC Mars-1, transferred to a desiccator within a Coy anaerobic environmental chamber, and maintained there for varying time periods. Following removal from the desiccator and rehydration, gas chromatographic measurements of methane indicated survival for varying time periods. Methanosarcina barkeri survived desiccation for 10 days, while Methanobacterium formicicum and Methanothermobacter wolfeii were able to survive for 25 days.

Identification and analysis of proton-translocating pyrophosphatases in the methanogenic archaeon Methanosarcina mazei

PubMed Central

Bäumer, Sebastian; Lentes, Sabine; Gottschalk, Gerhard; Deppenmeier, Uwe

2002-01-01

Analysis of genome sequence data from the methanogenic archaeon Methanosarcina mazei Gö1 revealed the existence of two open reading frames encoding proton-translocating pyrophosphatases (PPases). These open reading frames are linked by a 750-bp intergenic region containing TC-rich stretches and are transcribed in opposite directions. The corresponding polypeptides are referred to as Mvp1 and Mvp2 and consist of 671 and 676 amino acids, respectively. Both enzymes represent extremely hydrophobic, integral membrane proteins with 15 predicted transmembrane segments and an overall amino acid sequence similarity of 50.1%. Multiple sequence alignments revealed that Mvp1 is closely related to eukaryotic PPases, whereas Mvp2 shows highest homologies to bacterial PPases. Northern blot experiments with RNA from methanol-grown cells harvested in the mid-log growth phase indicated that only Mvp2 was produced under these conditions. Analysis of washed membranes showed that Mvp2 had a specific activity of 0.34 U mg (protein)–1. Proton translocation experiments with inverted membrane vesicles prepared from methanol-grown cells showed that hydrolysis of 1 mol of pyrophosphate was coupled to the translocation of about 1 mol of protons across the cytoplasmic membrane. Appropriate conditions for mvp1 expression could not be determined yet. The pyrophosphatases of M. mazei Gö1 represent the first examples of this enzyme class in methanogenic archaea and may be part of their energy-conserving system. Abbreviations: DCCD, N,N′-dicyclohexylcarbodiimide; PPase, inorganic pyrophosphatase; PPi, inorganic pyrophosphate; Δp, proton motive force. PMID:15803653

A sulfate-reducing bacterium with unusual growing capacity in moderately acidic conditions.

PubMed

Rampinelli, L R; Azevedo, R D; Teixeira, M C; Guerra-Sá, R; Leão, V A

2008-09-01

The use of sulfate-reducing bacteria (SRB) is a cost-effective route to treat sulfate- contaminated waters and precipitate metals. The isolation and characterization of a SRB strain from an AMD in a Brazilian tropical region site was carried out. With a moderately acidic pH (5.5), the C.1 strain began its growth and with continued growth, modified the pH accordingly. The strain under these conditions reduced sulfate at the same rate as an experiment performed using an initial pH of 7.0. The dsrB gene-based molecular approach was used for the characterization of this strain and its phylogenetic affiliation was similar to genus Desulfovibrio sp. The results show an SRB isolate with unexpected sulfate reducing capacity in moderately acidic conditions, bringing new possibilities for the treatment of AMD, as acid water would be neutralized to a mildly acidic condition.

Total fatty acid content of the plasma membrane of Saccharomyces cerevisiae is more responsible for ethanol tolerance than the degree of unsaturation.

PubMed

Kim, Hyun-Soo; Kim, Na-Rae; Choi, Wonja

2011-03-01

The effect of change in unsaturated fatty acid composition on ethanol tolerance in Saccharomyces cerevisiae overexpressing ScOLE1 (∆9 fatty acid desaturase gene of S. cerevisiae), CaFAD2 (∆12 fatty acid desaturase gene of Candida albicans), or CaFAD3 (ω3 fatty acid desaturase gene of C. albicans) was examined. ScOLE1 over-expression increased the total unsaturated fatty acid content and enhanced ethanol tolerance, compared with a control strain. In contrast, overexpression of CaFAD2 and CaFAD3, which led to production of linoleic acid (18:2) and α-linolenic acid (18:3), respectively, neither changed total unsaturated fatty acids nor enhanced ethanol tolerance. The total unsaturated fatty acid content rather than the degree of unsaturation is thus an important factor for ethanol tolerance.

Reactor performance of a 750 m(3) anaerobic digestion plant: varied substrate input conditions impacting methanogenic community.

PubMed

Wagner, Andreas Otto; Malin, Cornelia; Lins, Philipp; Gstraunthaler, Gudrun; Illmer, Paul

2014-10-01

A 750 m(3) anaerobic digester was studied over a half year period including a shift from good reactor performance to a reduced one. Various abiotic parameters like volatile fatty acids (VFA) (formic-, acetic-, propionic-, (iso-)butyric-, (iso-)valeric-, lactic acid), total C, total N, NH4 -N, and total proteins, as well as the organic matter content and dry mass were determined. In addition several process parameters such as temperature, pH, retention time and input of substrate and the concentrations of CH4, H2, CO2 and H2S within the reactor were monitored continuously. The present study aimed at the investigation of the abundance of acetogens and total cell numbers and the microbial methanogenic community as derived from PCR-dHPLC analysis in order to put it into context with the determined abiotic parameters. An influence of substrate quantity on the efficiency of the anaerobic digestion process was found as well as a shift from a hydrogenotrophic in times of good reactor performance towards an acetoclastic dominated methanogenic community in times of reduced reactor performance. After the change in substrate conditions it took the methano-archaeal community about 5-6 weeks to be affected but then changes occurred quickly. Copyright © 2014 Elsevier Ltd. All rights reserved.

The Effects of Perchlorates on the Permafrost Methanogens: Implication for Autotrophic Life on Mars.

PubMed

Shcherbakova, Viktoria; Oshurkova, Viktoria; Yoshimura, Yoshitaka

2015-09-09

The terrestrial permafrost represents a range of possible cryogenic extraterrestrial ecosystems on Earth-like planets without obvious surface ice, such as Mars. The autotrophic and chemolithotrophic psychrotolerant methanogens are more likely than aerobes to function as a model for life forms that may exist in frozen subsurface environments on Mars, which has no free oxygen, inaccessible organic matter, and extremely low amounts of unfrozen water. Our research on the genesis of methane, its content and distribution in permafrost horizons of different ages and origin demonstrated the presence of methane in permanently frozen fine-grained sediments. Earlier, we isolated and described four strains of methanogenic archaea of Methanobacterium and Methanosarcina genera from samples of Pliocene and Holocene permafrost from Eastern Siberia. In this paper we study the effect of sodium and magnesium perchlorates on growth of permafrost and nonpermafrost methanogens, and present evidence that permafrost hydogenotrophic methanogens are more resistant to the chaotropic agent found in Martian soil. In this paper we study the effect of sodium and magnesium perchlorates on the growth of permafrost and nonpermafrost methanogens, and present evidence that permafrost hydogenotrophic methanogens are more resistant to the chaotropic agent found in Martian soil. Furthermore, as shown in the studies strain M2(T) M. arcticum, probably can use perchlorate anion as an electron acceptor in anaerobic methane oxidation. Earth's subzero subsurface environments are the best approximation of environments on Mars, which is most likely to harbor methanogens; thus, a biochemical understanding of these pathways is expected to provide a basis for designing experiments to detect autotrophic methane-producing life forms on Mars.

The Effects of Perchlorates on the Permafrost Methanogens: Implication for Autotrophic Life on Mars

PubMed Central

Shcherbakova, Viktoria; Oshurkova, Viktoria; Yoshimura, Yoshitaka

2015-01-01

The terrestrial permafrost represents a range of possible cryogenic extraterrestrial ecosystems on Earth-like planets without obvious surface ice, such as Mars. The autotrophic and chemolithotrophic psychrotolerant methanogens are more likely than aerobes to function as a model for life forms that may exist in frozen subsurface environments on Mars, which has no free oxygen, inaccessible organic matter, and extremely low amounts of unfrozen water. Our research on the genesis of methane, its content and distribution in permafrost horizons of different ages and origin demonstrated the presence of methane in permanently frozen fine-grained sediments. Earlier, we isolated and described four strains of methanogenic archaea of Methanobacterium and Methanosarcina genera from samples of Pliocene and Holocene permafrost from Eastern Siberia. In this paper we study the effect of sodium and magnesium perchlorates on growth of permafrost and nonpermafrost methanogens, and present evidence that permafrost hydogenotrophic methanogens are more resistant to the chaotropic agent found in Martian soil. In this paper we study the effect of sodium and magnesium perchlorates on the growth of permafrost and nonpermafrost methanogens, and present evidence that permafrost hydogenotrophic methanogens are more resistant to the chaotropic agent found in Martian soil. Furthermore, as shown in the studies strain M2T M. arcticum, probably can use perchlorate anion as an electron acceptor in anaerobic methane oxidation. Earth’s subzero subsurface environments are the best approximation of environments on Mars, which is most likely to harbor methanogens; thus, a biochemical understanding of these pathways is expected to provide a basis for designing experiments to detect autotrophic methane-producing life forms on Mars. PMID:27682103

Altered macrophage arachidonic acid metabolism induced by endotoxin tolerance: characterization and mechanisms

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rogers, T.S.

Altered macrophage arachidonic acid (AA) metabolism may play a role in endotoxic shock and the phenomenon of endotoxin tolerance induced by repeated injections of endotoxin. Studies were initiated to characterize both lipoxygenase and cyclooxygenase metabolite formation by endotoxin tolerant and non-tolerant macrophages in response to 4 different stimuli, i.e., endotoxin, glucan, zymosan, and the calcium ionophore A23187. In contrast to previous reports of decreased prostaglandin synthesis by tolerant macrophages, A23187-stimulated immunoreactive (i) leukotriene (LT) C/sub 4/D/sub 4/ and prostaglandin (PG) E/sub 2/ production by tolerant cells was greater than that by non-tolerant controls (p <0.001). However, A23187-stimulated i6-keto PGF/sub 1a/more » levels were lower in tolerant macrophages compared to controls (P < 0.05). iL TC/sub 4/D/sub 4/ production was not significantly stimulated by endotoxin or glucan, but was stimulated by zymosan in non-tolerant cells. Synthesis of iLTB/sub 4/ by control macrophages was stimulated by endotoxin (p <0.01). The effect of tolerance on factors that affect AA release was investigated by measuring /sup 14/C-AA incorporation and release and phospholipase A/sub 2/ activity« less

Mutants of the pentose-fermenting yeast Pachysolen tannophilus tolerant to hardwood spent sulfite liquor and acetic acid.

PubMed

Harner, Nicole K; Bajwa, Paramjit K; Habash, Marc B; Trevors, Jack T; Austin, Glen D; Lee, Hung

2014-01-01

A strain development program was initiated to improve the tolerance of the pentose-fermenting yeast Pachysolen tannophilus to inhibitors in lignocellulosic hydrolysates. Several rounds of UV mutagenesis followed by screening were used to select for mutants of P. tannophilus NRRL Y2460 with improved tolerance to hardwood spent sulfite liquor (HW SSL) and acetic acid in separate selection lines. The wild type (WT) strain grew in 50 % (v/v) HW SSL while third round HW SSL mutants (designated UHW301, UHW302 and UHW303) grew in 60 % (v/v) HW SSL, with two of these isolates (UHW302 and UHW303) being viable and growing, respectively, in 70 % (v/v) HW SSL. In defined liquid media containing acetic acid, the WT strain grew in 0.70 % (w/v) acetic acid, while third round acetic acid mutants (designated UAA301, UAA302 and UAA303) grew in 0.80 % (w/v) acetic acid, with one isolate (UAA302) growing in 0.90 % (w/v) acetic acid. Cross-tolerance of HW SSL-tolerant mutants to acetic acid and vice versa was observed with UHW303 able to grow in 0.90 % (w/v) acetic acid and UAA302 growing in 60 % (v/v) HW SSL. The UV-induced mutants retained the ability to ferment glucose and xylose to ethanol in defined media. These mutants of P. tannophilus are of considerable interest for bioconversion of the sugars in lignocellulosic hydrolysates to ethanol.

Core Sulphate-Reducing Microorganisms in Metal-Removing Semi-Passive Biochemical Reactors and the Co-Occurrence of Methanogens

PubMed Central

Rezadehbashi, Maryam; Baldwin, Susan A.

2018-01-01

Biochemical reactors (BCRs) based on the stimulation of sulphate-reducing microorganisms (SRM) are emerging semi-passive remediation technologies for treatment of mine-influenced water. Their successful removal of metals and sulphate has been proven at the pilot-scale, but little is known about the types of SRM that grow in these systems and whether they are diverse or restricted to particular phylogenetic or taxonomic groups. A phylogenetic study of four established pilot-scale BCRs on three different mine sites compared the diversity of SRM growing in them. The mine sites were geographically distant from each other, nevertheless the BCRs selected for similar SRM types. Clostridia SRM related to Desulfosporosinus spp. known to be tolerant to high concentrations of copper were members of the core microbial community. Members of the SRM family Desulfobacteraceae were dominant, particularly those related to Desulfatirhabdium butyrativorans. Methanogens were dominant archaea and possibly were present at higher relative abundances than SRM in some BCRs. Both hydrogenotrophic and acetoclastic types were present. There were no strong negative or positive co-occurrence correlations of methanogen and SRM taxa. Knowing which SRM inhabit successfully operating BCRs allows practitioners to target these phylogenetic groups when selecting inoculum for future operations. PMID:29473875

Syntrophic acetate oxidation in two-phase (acid-methane) anaerobic digesters.

PubMed

Shimada, T; Morgenroth, E; Tandukar, M; Pavlostathis, S G; Smith, A; Raskin, L; Kilian, R E

2011-01-01

The microbial processes involved in two-phase anaerobic digestion were investigated by operating a laboratory-scale acid-phase (AP) reactor and analyzing two full-scale, two-phase anaerobic digesters operated under mesophilic (35 °C) conditions. The digesters received a blend of primary sludge and waste activated sludge (WAS). Methane levels of 20% in the laboratory-scale reactor indicated the presence of methanogenic activity in the AP. A phylogenetic analysis of an archaeal 16S rRNA gene clone library of one of the full-scale AP digesters showed that 82% and 5% of the clones were affiliated with the orders Methanobacteriales and Methanosarcinales, respectively. These results indicate that substantial levels of aceticlastic methanogens (order Methanosarcinales) were not maintained at the low solids retention times and acidic conditions (pH 5.2-5.5) of the AP, and that methanogenesis was carried out by hydrogen-utilizing methanogens of the order Methanobacteriales. Approximately 43, 31, and 9% of the archaeal clones from the methanogenic phase (MP) digester were affiliated with the orders Methanosarcinales, Methanomicrobiales, and Methanobacteriales, respectively. A phylogenetic analysis of a bacterial 16S rRNA gene clone library suggested the presence of acetate-oxidizing bacteria (close relatives of Thermacetogenium phaeum, 'Syntrophaceticus schinkii,' and Clostridium ultunense). The high abundance of hydrogen consuming methanogens and the presence of known acetate-oxidizing bacteria suggest that acetate utilization by acetate oxidizing bacteria in syntrophic interaction with hydrogen-utilizing methanogens was an important pathway in the second-stage of the two-phase digestion, which was operated at high ammonium-N concentrations (1.0 and 1.4 g/L). A modified version of the IWA Anaerobic Digestion Model No. 1 (ADM1) with extensions for syntrophic acetate oxidation and weak-acid inhibition adequately described the dynamic profiles of volatile acid production

Acid tolerance and acid shock response of Escherichia coli O157:H7 and non-O157:H7 isolates provide cross protection to sodium lactate and sodium chloride.

PubMed

Garren, D M; Harrison, M A; Russell, S M

1998-02-01

The survival of Escherichia coli O157:H7 and non-O157:H7 due to an enhanced acid tolerance response (ATR), and enhanced acid shock response (ASR), or the stationary phase protective system when exposed to lactic acid and the resulting cross protection against increased concentration of sodium chloride and sodium lactate was studied. Escherichia coli O157:H7 isolates (1932 and 009) and a non-O157:H7 strain (ATCC 23716) were grown to stationary phase at 32 degrees C and O157:H7 to one of two treatments in an attempt to either acid shock or acid adapt the survivors. Acid shocked cells were exposed to lactic acid at pH 4.0. Acid-adapted cells were first exposed to a pH of 5.5 and then an acid challenge of pH 4.0. Sodium lactate (10%, 20%, or 30%) or sodium chloride (5%, 10%, or 15%) were added to a minimal glucose medium after the acidification treatment. When acid shocked and acid adapted isolate 932 and strain ATCC 23716 tolerated the elevated levels of sodium lactate, and the strain ATCC 23716 tolerated the elevated levels of sodium chloride. Acid adaption allowed isolate 932 to tolerate higher levels of sodium chloride; however, the acid shocking did not provide the same protection. Neither of the acid treatment provided increased tolerance to sodium chloride for isolate E009. Evidence of cross protection against acid and sodium chloride or acid and sodium lactate in E. coli O157:H7 could point to a need for further evaluation of whether these combinations of preservation means are sufficient to control this pathogen.

Inactivation of the transcription factor mig1 (YGL035C) in Saccharomyces cerevisiae improves tolerance towards monocarboxylic weak acids: acetic, formic and levulinic acid.

PubMed

Balderas-Hernández, Victor E; Correia, Kevin; Mahadevan, Radhakrishnan

2018-06-06

Toxic concentrations of monocarboxylic weak acids present in lignocellulosic hydrolyzates affect cell integrity and fermentative performance of Saccharomyces cerevisiae. In this work, we report the deletion of the general catabolite repressor Mig1p as a strategy to improve the tolerance of S. cerevisiae towards inhibitory concentrations of acetic, formic or levulinic acid. In contrast with the wt yeast, where the growth and ethanol production were ceased in presence of acetic acid 5 g/L or formic acid 1.75 g/L (initial pH not adjusted), the m9 strain (Δmig1::kan) produced 4.06 ± 0.14 and 3.87 ± 0.06 g/L of ethanol, respectively. Also, m9 strain tolerated a higher concentration of 12.5 g/L acetic acid (initial pH adjusted to 4.5) without affecting its fermentative performance. Moreover, m9 strain produced 33% less acetic acid and 50-70% less glycerol in presence of weak acids, and consumed acetate and formate as carbon sources under aerobic conditions. Our results show that the deletion of Mig1p provides a single gene deletion target for improving the acid tolerance of yeast strains significantly.

Effect of didecyl dimethyl ammonium chloride on nitrate reduction in a mixed methanogenic culture.

PubMed

Tezel, U; Pierson, J A; Pavlostathis, S G

2008-01-01

The effect of the quaternary ammonium compound, didecyl dimethyl ammonium chloride (DDAC), on nitrate reduction was investigated at concentrations up to 100 mg/L in a batch assay using a mixed, mesophilic (35 degrees C) methanogenic culture. Glucose was used as the carbon and energy source and the initial nitrate concentration was 70 mg N/L. Dissimilatory nitrate reduction to ammonia (DNRA) and to dinitrogen (denitrification) were observed at DDAC concentrations up to 25 mg/L. At and above 50 mg DDAC/L, DNRA was inhibited and denitrification was incomplete resulting in accumulation of nitrous oxide. At DDAC concentrations above 10 mg/L, production of nitrous oxide, even transiently, resulted in complete, long-term inhibition of methanogenesis and accumulation of volatile fatty acids. Fermentation was inhibited at and above 75 mg DDAC/L. DDAC suppressed microbial growth and caused cell lysis at a concentration 50 mg/L or higher. Most of the added DDAC was adsorbed on the biomass. Over 96% of the added DDAC was recovered from all cultures at the end of the 100-days incubation period, indicating that DDAC did not degrade in the mixed methanogenic culture under the conditions of this study.

Enhanced butyric acid tolerance and bioproduction by Clostridium tyrobutyricum immobilized in a fibrous bed bioreactor.

PubMed

Jiang, Ling; Wang, Jufang; Liang, Shizhong; Cai, Jin; Xu, Zhinan; Cen, Peilin; Yang, Shangtian; Li, Shuang

2011-01-01

Repeated fed-batch fermentation of glucose by Clostridium tyrobutyricum immobilized in a fibrous bed bioreactor (FBB) was successfully employed to produce butyric acid at a high final concentration as well as to adapt a butyric-acid-tolerant strain. At the end of the eighth fed-batch fermentation, the butyric acid concentration reached 86.9 ± 2.17 g/L, which to our knowledge is the highest butyric acid concentration ever produced in the traditional fermentation process. To understand the mechanism and factors contributing to the improved butyric acid production and enhanced acid tolerance, adapted strains were harvested from the FBB and characterized for their physiological properties, including specific growth rate, acid-forming enzymes, intracellular pH, membrane-bound ATPase and cell morphology. Compared with the original culture used to seed the bioreactor, the adapted culture showed significantly reduced inhibition effects of butyric acid on specific growth rate, cellular activities of butyric-acid-forming enzyme phosphotransbutyrylase (PTB) and ATPase, together with elevated intracellular pH, and elongated rod morphology. © 2010 Wiley Periodicals, Inc.

Stereochemical studies of acyclic isoprenoids-XII. Lipids of methanogenic bacteria and possible contributions to sediments

USGS Publications Warehouse

Risatti, J.B.; Rowland, S.J.; Yon, D.A.; Maxwell, J.R.

1984-01-01

Abundant volatile lipids of Methanobacterium thermoautotrophicum and Methanosarcina barkeri include isoprenoid hydrocarbons (??? C30), and C15, C20 and C25 isoprenoid alcohols. M. barkeri contains 2,6,10,15,19-pentamethyleicosane, whose relative stereochemistry is the same as found in marine sediments, indicating that it is a marker of methanogenic activity. The C20, C30 and C25 alkenes in M. thermoautotrophicum also have a preferred sterochemistry; the latter have the 2,6,10,14,18-pentamethyleicosanyl skeleton, suggesting that the alkane in marine sediments may derive from methanogens. The stereochemistry of squalane in a marine sediment is also compatible with an origin in methanogens; in contrast, the stereochemistry of pristane in M. thermoautotrophicum indicates a fossil fuel contaminant origin, suggesting that this and certain other alkanes reported in archaebacteria might also be of contaminant origin. There is, therefore, little evidence at present that the pristane in immature marine sediments originates in methanogens. The C15 and C20 saturated alcohols in M. thermoautotrophicum have mainly the all-R configuration. If this is generally true for methanogens, the C20 alcohol in the Messel shale may originate mainly from methanogens, whereas that in the Green River shale may originate mainly from photosynthetic organisms. ?? 1984.

Methanogenic archaea are globally ubiquitous in aerated soils and become active under wet anoxic conditions

PubMed Central

Angel, Roey; Claus, Peter; Conrad, Ralf

2012-01-01

The prototypical representatives of the Euryarchaeota—the methanogens—are oxygen sensitive and are thought to occur only in highly reduced, anoxic environments. However, we found methanogens of the genera Methanosarcina and Methanocella to be present in many types of upland soils (including dryland soils) sampled globally. These methanogens could be readily activated by incubating the soils as slurry under anoxic conditions, as seen by rapid methane production within a few weeks, without any additional carbon source. Analysis of the archaeal 16S ribosomal RNA gene community profile in the incubated samples through terminal restriction fragment length polymorphism and quantification through quantitative PCR indicated dominance of Methanosarcina, whose gene copy numbers also correlated with methane production rates. Analysis of the δ13C of the methane further supported this, as the dominant methanogenic pathway was in most cases aceticlastic, which Methanocella cannot perform. Sequences of the key methanogenic enzyme methyl coenzyme M reductase retrieved from the soil samples before incubation confirmed that Methanosarcina and Methanocella are the dominant methanogens, though some sequences of Methanobrevibacter and Methanobacterium were also detected. The global occurrence of only two active methanogenic archaea supports the hypothesis that these are autochthonous members of the upland soil biome and are well adapted to their environment. PMID:22071343

Enhancing tolerance of rice (Oryza sativa) to simulated acid rain by exogenous abscisic acid.

PubMed

Wu, Xi; Liang, Chanjuan

2017-02-01

Abscisic acid (ABA) regulates much important plant physiological and biochemical processes and induces tolerance to different stresses. Here, we studied the regulation of exogenous ABA on adaptation of rice seedlings to simulated acid rain (SAR) stress by measuring biomass dry weight, stomatal conductance, net photosynthesis rate, nutrient elements, and endogenous hormones. The application of 10 μM ABA alleviated the SAR-induced inhibition on growth, stomatal conductance, net photosynthesis rate, and decreases in contents of nutrient (K, Mg, N, and P) and hormone (auxin, gibberellins, and zeatin). Moreover, 10 μM ABA could stimulate the Ca content as signaling molecules under SAR stress. Contrarily, the application of 100 μM ABA aggravated the SAR-induced inhibition on growth, stomatal conductance, net photosynthesis rate, and contents of nutrient and hormone. The results got after a 5-day recovery (without SAR) show that exogenous 10 μM ABA can promote self-restoration process in rice whereas 100 μM ABA hindered the restoration by increasing deficiency of nutrients and disturbing the balance of hormones. These results confirmed that exogenous ABA at proper concentration could enhance the tolerance of rice to SAR stress.

Metabolic pathways regulated by γ-aminobutyric acid (GABA) contributing to heat tolerance in creeping bentgrass (Agrostis stolonifera)

PubMed Central

Li, Zhou; Yu, Jingjin; Peng, Yan; Huang, Bingru

2016-01-01

γ-Aminobutyric acid is a non-protein amino acid involved in various metabolic processes. The objectives of this study were to examine whether increased GABA could improve heat tolerance in cool-season creeping bentgrass through physiological analysis, and to determine major metabolic pathways regulated by GABA through metabolic profiling. Plants were pretreated with 0.5 mM GABA or water before exposed to non-stressed condition (21/19 °C) or heat stress (35/30 °C) in controlled growth chambers for 35 d. The growth and physiological analysis demonstrated that exogenous GABA application significantly improved heat tolerance of creeping bentgrass. Metabolic profiling found that exogenous application of GABA led to increases in accumulations of amino acids (glutamic acid, aspartic acid, alanine, threonine, serine, and valine), organic acids (aconitic acid, malic acid, succinic acid, oxalic acid, and threonic acid), sugars (sucrose, fructose, glucose, galactose, and maltose), and sugar alcohols (mannitol and myo-inositol). These findings suggest that GABA-induced heat tolerance in creeping bentgrass could involve the enhancement of photosynthesis and ascorbate-glutathione cycle, the maintenance of osmotic adjustment, and the increase in GABA shunt. The increased GABA shunt could be the supply of intermediates to feed the tricarboxylic acid cycle of respiration metabolism during a long-term heat stress, thereby maintaining metabolic homeostasis. PMID:27455877

[Detection and diversity analysis of rumen methanogens in the co-cultures with anaerobic fungi].

PubMed

Cheng, Yan-fen; Mao, Sheng-yong; Pei, Cai-xia; Liu, Jian-xin; Zhu, Wei-yun

2006-12-01

Rumen methanogen diversity in the co-cultures with anaerobic fungi from goat rumen was analyzed. Mix-cultures of anaerobic fungi and methanogens were obtained from goat rumen using anaerobic fungal medium and the addition of penicillin and streptomycin and then subcultured 62 times by transferring cultures every 3 - 4d. Total DNA from the original rumen fluid and subcultured fungal cultures was used for PCR/DGGE and RFLP analysis. 16S rDNA of clones corresponding to representative OTUs were sequenced. Results showed that the diversity index (Shannon index) of the methanogens generated from DGGE profiles reduced from 1.32 to 0.99 from rumen fluid to fungal culture after 45 subculturing, with the lowest similarity of DGGE profiles at 34.7%. The Shannon index increased from 0.99 to 1.15 from the fungal culture after 45 subculturing to that after 62 subculturing, with the lowest similarity at 89.2% . A total of 5 OTUs were obtained from 69. clones using RFLP analysis and six clones representing the 5 OTUs respectively were sequenced. Of the 5 OTUs, three had their cloned 16S rDNA sequences most closely related to uncultured archaeal symbiont PA202 with the same similarity of 95 %, but had not closely related to any identified culturable methanogen. The rest two OTUs had their cloned 16S rDNA sequences sharing the same closest relative, uncultured rumen methanogen 956, with the same similarity of 97% .Their 16S rDNA sequences of these two OTUs also showed 97% similar to the closest identified culturable methanogen Methanobrevibacter sp. NT7. In conclusion, diverse yet unidentified rumen methanogen species exist in the co-cultures with anaerobic fungi isolated from the goat rumen.

The quantitative significance of Syntrophaceae and syntrophic partnerships in methanogenic degradation of crude oil alkanes

PubMed Central

Gray, N D; Sherry, A; Grant, R J; Rowan, A K; Hubert, C R J; Callbeck, C M; Aitken, C M; Jones, D M; Adams, J J; Larter, S R; Head, I M

2011-01-01

Libraries of 16S rRNA genes cloned from methanogenic oil degrading microcosms amended with North Sea crude oil and inoculated with estuarine sediment indicated that bacteria from the genera Smithella (Deltaproteobacteria, Syntrophaceace) and Marinobacter sp. (Gammaproteobacteria) were enriched during degradation. Growth yields and doubling times (36 days for both Smithella and Marinobacter) were determined using qPCR and quantitative data on alkanes, which were the predominant hydrocarbons degraded. The growth yield of the Smithella sp. [0.020 g(cell-C)/g(alkane-C)], assuming it utilized all alkanes removed was consistent with yields of bacteria that degrade hydrocarbons and other organic compounds in methanogenic consortia. Over 450 days of incubation predominance and exponential growth of Smithella was coincident with alkane removal and exponential accumulation of methane. This growth is consistent with Smithella's occurrence in near surface anoxic hydrocarbon degrading systems and their complete oxidation of crude oil alkanes to acetate and/or hydrogen in syntrophic partnership with methanogens in such systems. The calculated growth yield of the Marinobacter sp., assuming it grew on alkanes, was [0.0005 g(cell-C)/g(alkane-C)] suggesting that it played a minor role in alkane degradation. The dominant methanogens were hydrogenotrophs (Methanocalculus spp. from the Methanomicrobiales). Enrichment of hydrogen-oxidizing methanogens relative to acetoclastic methanogens was consistent with syntrophic acetate oxidation measured in methanogenic crude oil degrading enrichment cultures. qPCR of the Methanomicrobiales indicated growth characteristics consistent with measured rates of methane production and growth in partnership with Smithella. PMID:21914097

The quantitative significance of Syntrophaceae and syntrophic partnerships in methanogenic degradation of crude oil alkanes.

PubMed

Gray, N D; Sherry, A; Grant, R J; Rowan, A K; Hubert, C R J; Callbeck, C M; Aitken, C M; Jones, D M; Adams, J J; Larter, S R; Head, I M

2011-11-01

Libraries of 16S rRNA genes cloned from methanogenic oil degrading microcosms amended with North Sea crude oil and inoculated with estuarine sediment indicated that bacteria from the genera Smithella (Deltaproteobacteria, Syntrophaceace) and Marinobacter sp. (Gammaproteobacteria) were enriched during degradation. Growth yields and doubling times (36 days for both Smithella and Marinobacter) were determined using qPCR and quantitative data on alkanes, which were the predominant hydrocarbons degraded. The growth yield of the Smithella sp. [0.020 g(cell-C)/g(alkane-C)], assuming it utilized all alkanes removed was consistent with yields of bacteria that degrade hydrocarbons and other organic compounds in methanogenic consortia. Over 450 days of incubation predominance and exponential growth of Smithella was coincident with alkane removal and exponential accumulation of methane. This growth is consistent with Smithella's occurrence in near surface anoxic hydrocarbon degrading systems and their complete oxidation of crude oil alkanes to acetate and/or hydrogen in syntrophic partnership with methanogens in such systems. The calculated growth yield of the Marinobacter sp., assuming it grew on alkanes, was [0.0005 g(cell-C)/g(alkane-C)] suggesting that it played a minor role in alkane degradation. The dominant methanogens were hydrogenotrophs (Methanocalculus spp. from the Methanomicrobiales). Enrichment of hydrogen-oxidizing methanogens relative to acetoclastic methanogens was consistent with syntrophic acetate oxidation measured in methanogenic crude oil degrading enrichment cultures. qPCR of the Methanomicrobiales indicated growth characteristics consistent with measured rates of methane production and growth in partnership with Smithella. © 2011 Society for Applied Microbiology and Blackwell Publishing Ltd.

40 CFR 180.1068 - C12-C18 fatty acid potassium salts; exemption from the requirement of a tolerance.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 23 2010-07-01 2010-07-01 false C12-C18 fatty acid potassium salts... RESIDUES IN FOOD Exemptions From Tolerances § 180.1068 C12-C18 fatty acid potassium salts; exemption from the requirement of a tolerance. C12-C18 fatty acids (saturated and unsaturated) potassium salts are...

40 CFR 180.1068 - C12-C18 fatty acid potassium salts; exemption from the requirement of a tolerance.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 25 2013-07-01 2013-07-01 false C12-C18 fatty acid potassium salts... RESIDUES IN FOOD Exemptions From Tolerances § 180.1068 C12-C18 fatty acid potassium salts; exemption from the requirement of a tolerance. C12-C18 fatty acids (saturated and unsaturated) potassium salts are...

40 CFR 180.1068 - C12-C18 fatty acid potassium salts; exemption from the requirement of a tolerance.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 25 2012-07-01 2012-07-01 false C12-C18 fatty acid potassium salts... RESIDUES IN FOOD Exemptions From Tolerances § 180.1068 C12-C18 fatty acid potassium salts; exemption from the requirement of a tolerance. C12-C18 fatty acids (saturated and unsaturated) potassium salts are...

40 CFR 180.1068 - C12-C18 fatty acid potassium salts; exemption from the requirement of a tolerance.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 24 2011-07-01 2011-07-01 false C12-C18 fatty acid potassium salts... RESIDUES IN FOOD Exemptions From Tolerances § 180.1068 C12-C18 fatty acid potassium salts; exemption from the requirement of a tolerance. C12-C18 fatty acids (saturated and unsaturated) potassium salts are...

40 CFR 180.1068 - C12-C18 fatty acid potassium salts; exemption from the requirement of a tolerance.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 24 2014-07-01 2014-07-01 false C12-C18 fatty acid potassium salts... RESIDUES IN FOOD Exemptions From Tolerances § 180.1068 C12-C18 fatty acid potassium salts; exemption from the requirement of a tolerance. C12-C18 fatty acids (saturated and unsaturated) potassium salts are...

Molecular Characterization of Methanogenic Communities in Core Sediments of the Dajiuhu Peatland, Central China

NASA Astrophysics Data System (ADS)

Wang, R.; Wang, H.

2017-12-01

Methane (CH4) is an important greenhouse gas with a global warming potential 22 times greater than carbon dioxide. Large amounts of CH4 can be produced and released by methanogenesis in peatland ecosystems, which make peatland ecosystems play an important role in mediating global climate change. Here we report the abundance and distribution of methanogenic communities and their correlation with physicochemical parameters along two sediment cores in the Dajiuhu Peatland via quantitative PCR, clone library construction of functional genes and statistical analysis. Uncultured Group and Fen Cluster were found to be the dominant methanogens at the upper part of the cores, and Rice and Related Rice Cluster became dominant in the bottom of the cores. Quantitative PCR showed that abundances of methanogenic communities ranged from 104 to 106 copies/ng DNA throughout the cores. Canonical Correlation Analysis (CCA) indicated that dissolved oxygen (DO) (P=0.046, F=1.4) was the main factor significantly controlling methanogenic communities. Our results enhance the understanding of the compositions and variations of methanogenic communities vertically and greatly help us to further investigate process of microbial methanogenesis in Dajiuhu Peatland.

Use of Fatty Acid Methyl Ester Profiles to Compare Copper-Tolerant and Copper-Sensitive Strains of Pantoea ananatis.

PubMed

Nischwitz, C; Gitaitis, R; Sanders, H; Langston, D; Mullinix, B; Torrance, R; Boyhan, G; Zolobowska, L

2007-10-01

ABSTRACT A survey was conducted to evaluate differences in fatty acid methyl ester (FAME) profiles among strains of Pantoea ananatis, causal agent of center rot of onion (Allium cepa), isolated from 15 different onion cultivars in three different sites in Georgia. Differences in FAME composition were determined by plotting principal components (PCs) in two-dimensional plots. Euclidean distance squared (ED(2)) values indicated a high degree of similarity among strains. Plotting of PCs calculated from P. ananatis strains capable of growing on media amended with copper sulfate pentahydrate (200 mug/ml) indicated that copper-tolerant strains grouped into tight clusters separate from clusters formed by wild-type strains. However, unlike copper-sensitive strains, the copper-tolerant strains tended to cluster by location. A total of 80, 60, and 73% of the strains from Tift1, Tift2, and Tattnall, respectively, exhibited either confluent growth or partial growth on copper-amended medium. However, all strains were sensitive to a mixture of copper sulfate pentahydrate (200 mug/ml) and maneb (40 mug/ml). When copper-tolerant clones were analyzed and compared with their wild-type parents, in all cases the plotting of PCs developed from copper-tolerant clones formed tight clusters separate from clusters formed by the parents. Eigenvalues generated from these tests indicated that two components provided a good summary of the data, accounting for 98, 98, and 96% of the standardized variance for strains Pna 1-15B, Pna 1-12B, and Pna 2-5A, respectively. Furthermore, feature 4 (cis-9-hexadecenoic acid/2-hydroxy-13-methyltetradecanoic acid) and feature 7 (cis-9/trans-12/cis-7-octadecenoic acid) were the highest or second highest absolute values for PC1 in all three strains of the parents versus copper-tolerant clones, and hexadecanoic acid was the highest absolute value for PC2 in all three strains. Along with those fatty acids, dodecanoic acid and feature 3 (3-hydroxytetradecanoic

Relationship between Trophic Status and Methanogenic Pathways in Alaskan Peatlands

NASA Astrophysics Data System (ADS)

Zhang, L.; Liu, X.; Sidelinger, W.; Wang, Y.; Hines, M. E.; Langford, L.; Chanton, J.

2015-12-01

To improve predictions of naturally emitted CH4 from northern wetlands, it is necessary to further examine the methanogenic pathways in these wetlands. Stable isotope C ratios (δ13C) have been used as a robust tool to distinguish different pathways, but different sources of parent compounds (acetate and CO2) with unique δ13C may add complexity to previously established criteria. Large portions of peatlands accommodate a mixture of different sphagna and sedges. Plant species may look very similar and belong to the same genus but are different morphologically and physiologically. To better understand the relationships between surface vegetation patterns and methanogenic pathways, 26 peatland sites were studied in Fairbanks and Anchorage, Alaska in summers of 2014 and 2015. These sites were ordinated using multiple factor analysis into 3 clusters based on pH, temp, CH4 and volatile fatty acids production rates, δ13C values, and surface vegetation species/pattern. In the low-pH trophic cluster (pH~3.5), non-vascular/vascular plant ratios (NV/V) were ~ 0.87 and dominated by diverse Sphagnum species and specific sedges (Eriophorum vaginatum), and fermentation was the dominant end-point in decomposition with no CH4 detected. Although NV/V is about the same in the intermediate cluster (0.74) (pH~4.5), and Sphagnum squarrosum was largely present, both hydrogenotrophic (HM) and acetoclastic methanogenesis (AM) were very active. Syntrophy was present at certain sites, which may provide CO2 with unique δ13C for CH4 production. At the highest pH trophic cluster examined in this study (pH~5), non-vascular plants were almost not existent and Carex aquatilis dominated. CH4 production rates (mainly HM) were slower than those in the intermediate cluster and the apparent fractionation factor a was lower than in the sites with syntrophy, which warrants further investigation of the position and compound specific δ13C analysis of volatile fatty acids.

Long-term competition between sulfate reducing and methanogenic bacteria in UASB reactors treating volatile fatty acids.

PubMed

Omil, F; Lens, P; Visser, A; Hulshoff Pol, L W; Lettinga, G

1998-03-20

The competition between acetate utilizing methane-producing bacteria (MB) and sulfate-reducing bacteria (SRB) was studied in mesophilic (30 degrees C) upflow anaerobic sludge bed (UASB) reactors (upward velocity 1 m h-1; pH 8) treating volatile fatty acids and sulfate. The UASB reactors treated a VFA mixture (with an acetate:propionate:butyrate ratio of 5:3:2 on COD basis) or acetate as the sole substrate at different COD:sulfate ratios. The outcome of the competition was evaluated in terms of conversion rates and specific methanogenic and sulfidogenic activities. The COD:sulfate ratio was a key factor in the partitioning of acetate utilization between MB and SRB. In excess of sulfate (COD:sulfate ratio lower than 0.67), SRB became predominant over MB after prolonged reactor operation: 250 and 400 days were required to increase the amount of acetate used by SRB from 50 to 90% in the reactor treating, respectively, the VFA mixture or acetate as the sole substrate. The competition for acetate was further studied by dynamic simulations using a mathematical model based on the Monod kinetic parameters of acetate utilizing SRB and MB. The simulations confirmed the long term nature of the competition between these acetotrophs. A high reactor pH (+/-8), a short solid retention time (<150 days), and the presence of a substantial SRB population in the inoculum may considerably reduce the time required for acetate-utilising SRB to outcompete MB. Copyright 1998 John Wiley & Sons, Inc.

Complete genome sequence of Methanolinea tarda NOBI-1 T, a hydrogenotrophic methanogen isolated from methanogenic digester sludge

DOE PAGES

Yamamoto, Kyosuke; Tamaki, Hideyuki; Cadillo-Quiroz, Hinsby; ...

2014-09-04

In this study, we report a 2.0-Mb complete genome sequence of Methanolinea tarda NOBI-1 T, a methanogenic archaeon isolated from an anaerobic digested sludge. This is the first genome report of the genus Methanolinea isolate belonging to the family Methanoregulaceae, a recently proposed novel family within the order Methanomicrobiales.

Adaptive laboratory evolution of ethanologenic Zymomonas mobilis strain tolerant to furfural and acetic acid inhibitors.

PubMed

Shui, Zong-Xia; Qin, Han; Wu, Bo; Ruan, Zhi-yong; Wang, Lu-shang; Tan, Fu-Rong; Wang, Jing-Li; Tang, Xiao-Yu; Dai, Li-Chun; Hu, Guo-Quan; He, Ming-Xiong

2015-07-01

Furfural and acetic acid from lignocellulosic hydrolysates are the prevalent inhibitors to Zymomonas mobilis during cellulosic ethanol production. Developing a strain tolerant to furfural or acetic acid inhibitors is difficul by using rational engineering strategies due to poor understanding of their underlying molecular mechanisms. In this study, strategy of adaptive laboratory evolution (ALE) was used for development of a furfural and acetic acid-tolerant strain. After three round evolution, four evolved mutants (ZMA7-2, ZMA7-3, ZMF3-2, and ZMF3-3) that showed higher growth capacity were successfully obtained via ALE method. Based on the results of profiling of cell growth, glucose utilization, ethanol yield, and activity of key enzymes, two desired strains, ZMA7-2 and ZMF3-3, were achieved, which showed higher tolerance under 7 g/l acetic acid and 3 g/l furfural stress condition. Especially, it is the first report of Z. mobilis strain that could tolerate higher furfural. The best strain, Z. mobilis ZMF3-3, has showed 94.84% theoretical ethanol yield under 3-g/l furfural stress condition, and the theoretical ethanol yield of ZM4 is only 9.89%. Our study also demonstrated that ALE method might also be used as a powerful metabolic engineering tool for metabolic engineering in Z. mobilis. Furthermore, the two best strains could be used as novel host for further metabolic engineering in cellulosic ethanol or future biorefinery. Importantly, the two strains may also be used as novel-tolerant model organisms for the genetic mechanism on the "omics" level, which will provide some useful information for inverse metabolic engineering.

Koch–Haaf reaction of adamantanols in an acid-tolerant hastelloy-made microreactor

PubMed Central

Mukai, Yu

2011-01-01

Summary The Koch–Haaf reaction of adamantanols was successfully carried out in a microflow system at room temperature. By combining an acid-tolerant hastelloy-made micromixer, a PTFE tube, and a hastelloy-made microextraction unit, a packaged reaction-to-workup system was developed. By means of the present system, the multigram scale synthesis of 1-adamantanecarboxylic acid was achieved in ca. one hour operation. PMID:21977213

The Branched-Chain Amino Acid Aminotransferase Encoded by ilvE Is Involved in Acid Tolerance in Streptococcus mutans

PubMed Central

Santiago, Brendaliz; MacGilvray, Matthew; Faustoferri, Roberta C.

2012-01-01

The ability of Streptococcus mutans to produce and tolerate organic acids from carbohydrate metabolism represents a major virulence factor responsible for the formation of carious lesions. Pyruvate is a key metabolic intermediate that, when rerouted to other metabolic pathways such as amino acid biosynthesis, results in the alleviation of acid stress by reducing acid end products and aiding in maintenance of intracellular pH. Amino acid biosynthetic genes such as ilvC and ilvE were identified as being upregulated in a proteome analysis of Streptococcus mutans under acid stress conditions (A. C. Len, D. W. Harty, and N. A. Jacques, Microbiology 150:1353–1366, 2004). In Lactococcus lactis and Staphylococcus carnosus, the ilvE gene product is involved with biosynthesis and degradation of branched-chain amino acids, as well as in the production of branched-chain fatty acids (B. Ganesan and B. C. Weimer, Appl. Environ. Microbiol. 70:638–641, 2004; S. M. Madsen et al., Appl. Environ. Microbiol. 68:4007–4014, 2002; and M. Yvon, S. Thirouin, L. Rijnen, D. Fromentier, and J. C. Gripon, Appl. Environ. Microbiol. 63:414–419, 1997). Here we constructed and characterized an ilvE deletion mutant of S. mutans UA159. Growth experiments revealed that the ilvE mutant strain has a lag in growth when nutritionally limited for branched-chain amino acids. We further demonstrated that the loss of ilvE causes a decrease in acid tolerance. The ilvE strain exhibits a defect in F1-Fo ATPase activity and has reduced catabolic activity for isoleucine and valine. Results from transcriptional studies showed that the ilvE promoter is upregulated during growth at low pH. Collectively, the results of this investigation show that amino acid metabolism is a component of the acid-adaptive repertoire of S. mutans. PMID:22328677

Free acetic acid as the key factor for the inhibition of hydrogenotrophic methanogenesis in mesophilic mixed culture fermentation.

PubMed

Zhang, Wei; Dai, Kun; Xia, Xiu-Yang; Wang, Hua-Jie; Chen, Yun; Lu, Yong-Ze; Zhang, Fang; Zeng, Raymond Jianxiong

2018-05-18

The inhibition of acetate under acidic pH is an ideal way to reduce methanogenesis in mesophilic mixed culture fermentation (MCF). However, the effects of acetate concentration and acidic pH on methanogenesis remain unclear. Besides, although hydrogenotrophic methanogens can be suitable targets in MCF, they are generally ignored. Therefore, we intentionally enriched hydrogenotrophic methanogens and found that free acetic acid (FAA, x) concentration and specific methanogenic activity (SMA, y) were correlated according to the equation: y = 0.86 × 0.31/(0.31 + x) (R 2  = 0.909). The SMA was decreased by 50% and 90% at the FAA concentrations of 0.31 and 2.36 g/L, respectively. The coenzyme M concentration and relative electron transport activity agreed well with the FAA concentration. Moreover, the methanogenic activity could not be recovered when the FAA concentration exceeded 0.81 g/L. These findings indicated that neither acetate nor acidic pH, but FAA was the key factor to inhibit methanogenesis in MCF. Copyright © 2018 Elsevier Ltd. All rights reserved.

Effect of Nickel Levels on Hydrogen Partial Pressure and Methane Production in Methanogens

PubMed Central

2016-01-01

Hydrogen (H2) consumption and methane (CH4) production in pure cultures of three different methanogens were investigated during cultivation with 0, 0.2 and 4.21 μM added nickel (Ni). The results showed that the level of dissolved Ni in the anaerobic growth medium did not notably affect CH4 production in the cytochrome-free methanogenic species Methanobacterium bryantii and Methanoculleus bourgensis MAB1, but affected CH4 formation rate in the cytochrome-containing Methanosarcina barkeri grown on H2 and CO2. Methanosarcina barkeri also had the highest amounts of Ni in its cells, indicating that more Ni is needed by cytochrome-containing than by cytochrome-free methanogenic species. The concentration of Ni affected threshold values of H2 partial pressure (pH2) for all three methanogen species studied, with M. bourgensis MAB1 reaching pH2 values as low as 0.1 Pa when Ni was available in amounts used in normal anaerobic growth medium. To our knowledge, this is the lowest pH2 threshold recorded to date in pure methanogen culture, which suggests that M.bourgensis MAB1 have a competitive advantage over other species through its ability to grow at low H2 concentrations. Our study has implications for research on the H2-driven deep subsurface biosphere and biogas reactor performance. PMID:27992585

Effect of Nickel Levels on Hydrogen Partial Pressure and Methane Production in Methanogens.

PubMed

Neubeck, Anna; Sjöberg, Susanne; Price, Alex; Callac, Nolwenn; Schnürer, Anna

2016-01-01

Hydrogen (H2) consumption and methane (CH4) production in pure cultures of three different methanogens were investigated during cultivation with 0, 0.2 and 4.21 μM added nickel (Ni). The results showed that the level of dissolved Ni in the anaerobic growth medium did not notably affect CH4 production in the cytochrome-free methanogenic species Methanobacterium bryantii and Methanoculleus bourgensis MAB1, but affected CH4 formation rate in the cytochrome-containing Methanosarcina barkeri grown on H2 and CO2. Methanosarcina barkeri also had the highest amounts of Ni in its cells, indicating that more Ni is needed by cytochrome-containing than by cytochrome-free methanogenic species. The concentration of Ni affected threshold values of H2 partial pressure (pH2) for all three methanogen species studied, with M. bourgensis MAB1 reaching pH2 values as low as 0.1 Pa when Ni was available in amounts used in normal anaerobic growth medium. To our knowledge, this is the lowest pH2 threshold recorded to date in pure methanogen culture, which suggests that M.bourgensis MAB1 have a competitive advantage over other species through its ability to grow at low H2 concentrations. Our study has implications for research on the H2-driven deep subsurface biosphere and biogas reactor performance.

Low Temperature-Induced Decrease in trans-Δ3-Hexadecenoic Acid Content Is Correlated with Freezing Tolerance in Cereals 1

PubMed Central

Huner, Norman P. A.; Williams, John P.; Maissan, Ellen E.; Myscich, Elizabeth G.; Krol, Marianna; Laroche, Andre; Singh, Jasbir

1989-01-01

The effect of growth at 5°C on the trans-Δ3-hexadecenoic acid content of phosphatidyl(d)glycerol was examined in a total of eight cultivars of rye (Secale cereale L.) and what (Triticum aestivum L.) of varying freezing tolerance. In these monocots, low temperature growth caused decreases in the trans-Δ3-hexadecenoic acid content of between 0 and 74% with concomitant increases in the palmitic acid content of phosphatidyl(d)glycerol. These trends were observed for whole leaf extracts as well as isolated thylakoids. The low growth temperature-induced decrease in the trans-Δ3-hexadecenoic acid content was shown to be a linear function (r2 = 0.954) of freezing tolerance in these cultivars. Of the six cold tolerant dicotyledonous species examined, only Brassica and Arabidopsis thaliana L. cv Columbia exhibited a 42% and 65% decrease, respectively, in trans-Δ3-hexadecenoic acid content. Thus, the relationship between the change in trans-Δ3-hexadecenoic acid content of phosphatidyl(d)glycerol and freezing tolerance cannot be considered a general one for all cold tolerant plant species. However, species which exhibited a low growth temperature-induced decrease in trans-Δ3-hexadecenoic acid also exhibited a concomitant shift in the in vitro organization of the light harvesting complex II from a predominantly oligomeric form to the monomeric form. We conclude that the proposed role of phosphatidyl(d)glycerol in modulating the organization of light harvesting complex II as a function of growth temperature manifests itself to varying degrees in different plant species. A possible physiological role for this phenomenon with respect to low temperature acclimation and freezing tolerance in cereals is discussed. PMID:16666505

Methanogenic degradation of petroleum hydrocarbons in subsurface environments remediation, heavy oil formation, and energy recovery.

PubMed

Gray, N D; Sherry, A; Hubert, C; Dolfing, J; Head, I M

2010-01-01

Hydrocarbons are common constituents of surface, shallow, and deep-subsurface environments. Under anaerobic conditions, hydrocarbons can be degraded to methane by methanogenic microbial consortia. This degradation process is widespread in the geosphere. In comparison with other anaerobic processes, methanogenic hydrocarbon degradation is more sustainable over geological time scales because replenishment of an exogenous electron acceptor is not required. As a consequence, this process has been responsible for the formation of the world's vast deposits of heavy oil, which far exceed conventional oil assets such as those found in the Middle East. Methanogenic degradation is also a potentially important component of attenuation in hydrocarbon contamination plumes. Studies of the organisms, syntrophic partnerships, mechanisms, and geochemical signatures associated with methanogenic hydrocarbon degradation have identified common themes and diagnostic markers for this process in the subsurface. These studies have also identified the potential to engineer methanogenic processes to enhance the recovery of energy assets as biogenic methane from residual oils stranded in petroleum systems. Copyright 2010 Elsevier Inc. All rights reserved.

Guiding principle for crystalline Si photovoltaic modules with high tolerance to acetic acid

NASA Astrophysics Data System (ADS)

Masuda, Atsushi; Hara, Yukiko

2018-04-01

A guiding principle for highly reliable crystalline Si photovoltaic modules, especially those with high tolerance to acetic acid generated by hydrolysis reaction between water vapor and an ethylene-vinyl acetate (EVA) encapsulant, is proposed. Degradation behavior evaluated by the damp heat test strongly depends on Ag finger electrodes and also EVA encapsulants. The acetic acid concentration in EVA on the glass side directly determines the degradation behavior. The most important factor for high tolerance is the type of Ag finger electrode materials when using an EVA encapsulant. Photovoltaic modules using newly developed crystalline Si cells with improved Ag finger electrode materials keep their maximum power of 80% of the initial value even after the damp heat test at 85 °C and 85% relative humidity for 10000 h. The pattern of dark regions in electroluminescence images is also discussed on the basis of the dynamics of acetic acid in the modules.

Changes in methanogenic substrate utilization and communities with depth in a salt-marsh, creek sediment in southern England

NASA Astrophysics Data System (ADS)

John Parkes, R.; Brock, Fiona; Banning, Natasha; Hornibrook, Edward R. C.; Roussel, Erwan G.; Weightman, Andrew J.; Fry, John C.

2012-01-01

A combined biogeochemical and molecular genetic study of creek sediments (down to 65 cm depth) from Arne Peninsula salt-marsh (Dorset, UK) determined the substrates used for methanogenesis and the distribution of the common methanogens, Methanosarcinales and Methanomicrobiales capable of metabolising these substrates. Methane concentrations increased by 11 cm, despite pore water sulphate not being removed until 45 cm. Neither upward methane diffusion or anaerobic oxidation of methane seemed to be important in this zone. In the near-surface sulphate-reduction zone (5-25 cm) turnover time to methane for the non-competitive methanogenic substrate trimethylamine was most rapid (80 days), and were much longer for acetate (7900 days), methanol (40,500 days) and bicarbonate (361,600 days). Methylamine-utilizing Methanosarcinales were the dominant (60-95%) methanogens in this zone. In deeper sediments rates of methanogenesis from competitive substrates increased substantially, with acetate methanogenic rates becoming ˜100 times greater than H 2/CO 2 methanogenesis below 50 cm. In addition, there was a dramatic change in methanogen diversity with obligate acetate-utilizing, Methanosaeta related sequences being dominant. At a similar depth methanol turnover to methane increased to its most rapid (1700 days). This activity pattern is consistent with deeper methanogen populations (55 cm) being dominated by acetate-utilizing Methanosaeta with H 2/CO 2 and alcohol-utilizing Methanomicrobiales also present. Hence, there is close relationship between the depth distribution of methanogenic substrate utilization and specific methanogens that can utilize these compounds. It is unusual for acetate to be the dominant methanogenic substrate in coastal sediments and δ13C-CH 4 values (-74 to -71‰) were atypical for acetate methanogenesis, suggesting that common stable isotope proxy models may not apply well in this type of dynamic anoxic sediment, with multiple methanogenic substrates.

Roles of H2 uptake hydrogenases in Shigella flexneri acid tolerance

PubMed Central

McNorton, Mykeshia M.

2012-01-01

Hydrogenases play many roles in bacterial physiology, and use of H2 by the uptake-type enzymes of animal pathogens is of particular interest. Hydrogenases have never been studied in the pathogen Shigella, so targeted mutant strains were individually generated in the two Shigella flexneri H2-uptake enzymes (Hya and Hyb) and in the H2-evolving enzyme (Hyc) to address their roles. Under anaerobic fermentative conditions, a Hya mutant strain (hya) was unable to oxidize H2, while a Hyb mutant strain oxidized H2 like the wild-type. A hyc strain oxidized more exogenously added hydrogen than the parent. Fluorescence ratio imaging with dye JC-1 (5,5′,6,6′-tetrachloro-1,1′,3,3′-tetraethylbenzimidazolylcarbocyanine iodide) showed that the parent strain generated a membrane potential 15 times greater than hya. The hya mutant was also by far the most acid-sensitive strain, being even more acid-sensitive than a mutant strain in the known acid-combating glutamate-dependent acid-resistance pathway (GDAR pathway). In severe acid-challenge experiments, the addition of glutamate to hya restored survivability, and this ability was attributed in part to the GDAR system (removes intracellular protons) by mutant strain (e.g. hya/gadBC double mutant) analyses. However, mutant strain phenotypes indicated that a larger portion of the glutamate-rescued acid tolerance was independent of GadBC. The acid tolerance of the hya strains was aided by adding chloride ions to the growth medium. The whole-cell Hya enzyme became more active upon acid exposure (20 min), based on assays of hyc. Indeed, the very high rates of Shigella H2 oxidation by Hya in acid can supply each cell with 2.4×108 protons min−1. Electrons generated from Hya-mediated H2 oxidation at the inner membrane likely counteract cytoplasmic positive charge stress, while abundant proton pools deposited periplasmically likely repel proton influx during severe acid stress. PMID:22628482

Ruminal Fermentation of Anti-Methanogenic Nitrate- and Nitro-Containing Forages In Vitro

PubMed Central

Anderson, Robin C.; Ripley, Laura H.; Bowman, Jan G. P.; Callaway, Todd R.; Genovese, Kenneth J.; Beier, Ross C.; Harvey, Roger B.; Nisbet, David J.

2016-01-01

Nitrate, 3-nitro-1-propionic acid (NPA) and 3-nitro-1-propanol (NPOH) can accumulate in forages and be poisonous to animals if consumed in high enough amounts. These chemicals are also recognized as potent anti-methanogenic compounds, but plants naturally containing these chemicals have been studied little in this regard. Presently, we found that nitrate-, NPA-, or NPOH-containing forages effectively decreased methane production, by 35–87%, during in vitro fermentation by mixed cultures of ruminal microbes compared to fermentation by cultures incubated similarly with alfalfa. Methane production was further decreased during the incubation of mixed cultures also inoculated with Denitrobacterium detoxificans, a ruminal bacterium known to metabolize nitrate, NPA, and NPOH. Inhibition of methanogens within the mixed cultures was greatest with the NPA- and NPOH-containing forages. Hydrogen accumulated in all the mixed cultures incubated with forages containing nitrate, NPA or NPOH and was dramatically higher, exceeding 40 μmol hydrogen/mL, in mixed cultures incubated with NPA-containing forage but not inoculated with D. detoxificans. This possibly reflects the inhibition of hydrogenase-catalyzed uptake of hydrogen produced via conversion of 50 μmol added formate per milliliter to hydrogen. Accumulations of volatile fatty acids revealed compensatory changes in fermentation in mixed cultures incubated with the nitrate-, NPA-, and NPOH-containing forages as evidenced by lower accumulations of acetate, and in some cases, higher accumulations of butyrate and lower accumulations of ammonia, iso-buytrate, and iso-valerate compared to cultures incubated with alfalfa. Results reveal that nitrate, NPA, and NPOH that accumulate naturally in forages can be made available within ruminal incubations to inhibit methanogenesis. Further research is warranted to determine if diets can be formulated with nitrate-, NPA-, and NPOH-containing forages to achieve efficacious mitigation

Establishment of a Methanogenic Benzene-Degrading Culture and its Implication in Bioremediation

NASA Astrophysics Data System (ADS)

Qiao, W.; Luo, F.; Bawa, N.; Guo, S.; Ye, S.; Edwards, E.

2017-12-01

Benzene is a known human carcinogen and it is a common pollutant in groundwater, mainly resulting from petrochemical industry. Anaerobic degradation of benzene has significant advantages over aerobic processes for in situ bioremediation. In this study, new methanogenic and sulfate-reducing benzene degrading cultures have been enriched. Microbial community composition was characterized with two other previously established benzene-degrading cultures, and their potential use in bioaugmentation is investigated. In this study, a lab microcosm study was conducted anaerobically with contaminated soil and groundwater from a former chemical plant. Benzene degradation was observed in the presence of co-contaminants and electron donor. Through repetitive amendment of benzene, two enrichment cultures have been developed under sulfate and methanogenic conditions. Results from DNA amplicon sequencing and qPCR analysis revealed that an organism similar to previously described benzene-degrading Deltaproteobacterium has been enriched. The microbial community of this culture was compared with other two methanogenic benzene-degrading enrichment cultures that were derived from an oil refinery and a decommissioned gasoline station, and have been maintained for decades. Deltaproteobacterium ORM2-like microbes were dominate in all enrichment cultures, which brought to light benzene-degrading microbes, ORM2 were enriched under different geological conditions distributed around the world. The relative abundance of methanogens was much lower compared to previously established cultures, although substantial amount of methane was produced. The peripheral organisms also vary. To investigate effectiveness of using ORM2-dominant enrichment cultures in bioremediation, microcosm studies were set up using contaminated materials, and a ORM2-dominating methanogenic benzene-degrading culture was used for bioaugmentation. Results revealed that benzene degradation was speeded up under methanogenic or

Reduction of structural Fe(III) in nontronite by methanogen Methanosarcina barkeri

USGS Publications Warehouse

Liu, D.; Dong, Hailiang H.; Bishop, M.E.; Wang, Hongfang; Agrawal, A.; Tritschler, S.; Eberl, D.D.; Xie, S.

2011-01-01

Clay minerals and methanogens are ubiquitous and co-exist in anoxic environments, yet it is unclear whether methanogens are able to reduce structural Fe(III) in clay minerals. In this study, the ability of methanogen Methanosarcina barkeri to reduce structural Fe(III) in iron-rich smectite (nontronite NAu-2) and the relationship between iron reduction and methanogenesis were investigated. Bioreduction experiments were conducted in growth medium using three types of substrate: H2/CO2, methanol, and acetate. Time course methane production and hydrogen consumption were measured by gas chromatography. M. barkeri was able to reduce structural Fe(III) in NAu-2 with H2/CO2 and methanol as substrate, but not with acetate. The extent of bioreduction, as measured by the 1,10-phenanthroline method, was 7-13% with H2/CO2 as substrate, depending on nontronite concentration (5-10g/L). The extent was higher when methanol was used as a substrate, reaching 25-33%. Methanogenesis was inhibited by Fe(III) reduction in the H2/CO2 culture, but enhanced when methanol was used. High charge smectite and biogenic silica formed as a result of bioreduction. Our results suggest that methanogens may play an important role in biogeochemical cycling of iron in clay minerals and may have important implications for the global methane budget. ?? 2010 Elsevier Ltd.

Withania somnifera attenuates acid production, acid tolerance and extra-cellular polysaccharide formation of Streptococcus mutans biofilms.

PubMed

Pandit, Santosh; Song, Kwang-Yeob; Jeon, Jae-Gyu

2014-01-01

Withania somnifera (Ashwagandha) is a plant of the Solanaceae family. It has been widely used as a remedy for a variety of ailments in India and Nepal. The plant has also been used as a controlling agent for dental diseases. The aim of the present study was to evaluate the activity of the methanol extract of W. somnifera against the physiological ability of cariogenic biofilms and to identify the components of the extract. To determine the activity of the extract, assays for sucrose-dependent bacterial adherence, glycolytic acid production, acid tolerance, and extracellular polysaccharide formation were performed using Streptococcus mutans biofilms. The viability change of S. mutans biofilms cells was also determined. A phytochemical analysis of the extract was performed using TLC and LC/MS/MS. The extract showed inhibitory effects on sucrose-dependent bacterial adherence (≥ 100 μg/ml), glycolytic acid production (≥ 300 μg/ml), acid tolerance (≥ 300 μg/ml), and extracellular polysaccharide formation (≥ 300 μg/ml) of S. mutans biofilms. However, the extract did not alter the viability of S. mutans biofilms cells in all concentrations tested. Based on the phytochemical analysis, the activity of the extract may be related to the presence of alkaloids, anthrones, coumarines, anthraquinones, terpenoids, flavonoids, and steroid lactones (withanolide A, withaferin A, withanolide B, withanoside IV, and 12-deoxy withastramonolide). These data indicate that W. somnifera may be a potential agent for restraining the physiological ability of cariogenic biofilms.

Polyphasic Analyses of Methanogenic Archaeal Communities in Agricultural Biogas Plants▿

PubMed Central

Nettmann, E.; Bergmann, I.; Pramschüfer, S.; Mundt, K.; Plogsties, V.; Herrmann, C.; Klocke, M.

2010-01-01

Knowledge of the microbial consortia participating in the generation of biogas, especially in methane formation, is still limited. To overcome this limitation, the methanogenic archaeal communities in six full-scale biogas plants supplied with different liquid manures and renewable raw materials as substrates were analyzed by a polyphasic approach. Fluorescence in situ hybridization (FISH) was carried out to quantify the methanogenic Archaea in the reactor samples. In addition, quantitative real-time PCR (Q-PCR) was used to support and complete the FISH analysis. Five of the six biogas reactors were dominated by hydrogenotrophic Methanomicrobiales. The average values were between 60 to 63% of archaeal cell counts (FISH) and 61 to 99% of archaeal 16S rRNA gene copies (Q-PCR). Within this order, Methanoculleus was found to be the predominant genus as determined by amplified rRNA gene restriction analysis. The aceticlastic family Methanosaetaceae was determined to be the dominant methanogenic group in only one biogas reactor, with average values for Q-PCR and FISH between 64% and 72%. Additionally, in three biogas reactors hitherto uncharacterized but potentially methanogenic species were detected. They showed closest accordance with nucleotide sequences of the hitherto unclassified CA-11 (85%) and ARC-I (98%) clusters. These results point to hydrogenotrophic methanogenesis as a predominant pathway for methane synthesis in five of the six analyzed biogas plants. In addition, a correlation between the absence of Methanosaetaceae in the biogas reactors and high concentrations of total ammonia (sum of NH3 and NH4+) was observed. PMID:20154117

Differences in the methanogen population exist in sika deer (Cervus nippon) fed different diets in China.

PubMed

Li, Zhi Peng; Liu, Han Lu; Jin, Chun Ai; Cui, Xue Zhe; Jing, Yi; Yang, Fu He; Li, Guang Yu; Wright, André-Denis G

2013-11-01

Understanding the methanogen structure from sika deer (Cervus nippon) in China may be beneficial to methane mitigation. In the present preliminary study, we investigated the methanogen community in the rumen of domesticated sika deer fed either tannin-rich plants (oak leaf, OL group) or corn stalk (CS group) using 16S rRNA gene clone libraries. Overall, we obtained 197 clone sequences, revealing 146 unique phylotypes, which were assigned to 36 operational taxonomic units at the species level (98 % identity). Methanogens related to the genus Methanobrevibacter were the predominant phylotypes representing 83.9 % (OL library) and 85.9 % (CS library) of the clones. Methanobrevibacter millerae was the most abundant species in both libraries, but the proportion of M. millerae-related clones in the CS library was higher than in the OL library (69.5 and 51.4 %, respectively). Moreover, Methanobrevibacter wolinii-related clones (32.5 %) were predominant in the OL library. Methanobrevibacter smithii-related clones and Methanobrevibacter ruminantium-related clones accounted for 6.5 and 6.6 % in the CS library, respectively. However, these clones were absent from the OL library. The concentrations of butyrate and total short-chain fatty acids (SCFAs) were significantly higher in the OL group, but the concentrations of acetate, propionate, and valerate and the acetate to propionate ratio in the OL group were not significantly different between the two groups. Tannin-rich plants may have affected the distribution of genus Methanobrevibacter phylotypes at the species level and the concentration and composition of SCFAs.

Enhanced butyric acid tolerance and production by Class I heat shock protein-overproducing Clostridium tyrobutyricum ATCC 25755.

PubMed

Suo, Yukai; Luo, Sheng; Zhang, Yanan; Liao, Zhengping; Wang, Jufang

2017-08-01

The response of Clostridium tyrobutyricum to butyric acid stress involves various stress-related genes, and therefore overexpression of stress-related genes can improve butyric acid tolerance and yield. Class I heat shock proteins (HSPs) play an important role in the process of protecting bacteria from sudden changes of extracellular stress by assisting protein folding correctly. The results of quantitative real-time PCR indicated that the Class I HSGs grpE, dnaK, dnaJ, groEL, groES, and htpG were significantly upregulated under butyric acid stress, especially the dnaK and groE operons. Overexpression of groESL and htpG could significantly improve the tolerance of C. tyrobutyricum to butyric acid, while overexpression of dnaK and dnaJ showed negative effects on butyric acid tolerance. Acid production was also significantly promoted by increased GroESL expression levels; the final butyric acid and acetic acid concentrations were 28.2 and 38% higher for C. tyrobutyricum ATCC 25755/groESL than for the wild-type strain. In addition, when fed-batch fermentation was carried out using cell immobilization in a fibrous-bed bioreactor, the butyric acid yield produced by C. tyrobutyricum ATCC 25755/groESL reached 52.2 g/L, much higher than that for the control. The improved butyric acid yield is probably attributable to the high GroES and GroEL levels, which can stabilize the biosynthetic machinery of C. tyrobutyricum under extracellular butyric acid stress.

Methanogenic archaea in marcellus shale: a possible mechanism for enhanced gas recovery in unconventional shale resources.

PubMed

Tucker, Yael Tarlovsky; Kotcon, James; Mroz, Thomas

2015-06-02

Marcellus Shale occurs at depths of 1.5-2.5 km (5000 to 8000 feet) where most geologists generally assume that thermogenic processes are the only source of natural gas. However, methanogens in produced fluids and isotopic signatures of biogenic methane in this deep shale have recently been discovered. This study explores whether those methanogens are indigenous to the shale or are introduced during drilling and hydraulic fracturing. DNA was extracted from Marcellus Shale core samples, preinjected fluids, and produced fluids and was analyzed using Miseq sequencing of 16s rRNA genes. Methanogens present in shale cores were similar to methanogens in produced fluids. No methanogens were detected in injected fluids, suggesting that this is an unlikely source and that they may be native to the shale itself. Bench-top methane production tests of shale core and produced fluids suggest that these organisms are alive and active under simulated reservoir conditions. Growth conditions designed to simulate the hydrofracture processes indicated somewhat increased methane production; however, fluids alone produced relatively little methane. Together, these results suggest that some biogenic methane may be produced in these wells and that hydrofracture fluids currently used to stimulate gas recovery could stimulate methanogens and their rate of producing methane.

Aluminium tolerance of root hairs underlies genotypic differences in rhizosheath size of wheat (Triticum aestivum) grown on acid soil.

PubMed

Delhaize, Emmanuel; James, Richard A; Ryan, Peter R

2012-08-01

We found significant genetic variation in the ability of wheat (Triticum aestivum) to form rhizosheaths on acid soil and assessed whether differences in aluminium (Al(3+) ) tolerance of root hairs between genotypes was the physiological basis for this genetic variation. A method was developed to rapidly screen rhizosheath size in a range of wheat genotypes. Backcrossed populations were generated from cv Fronteira (large rhizosheath) using cv EGA-Burke (small rhizosheath) as the recurrent parent. A positive correlation existed between rhizosheath size on acid soil and root hair length. In hydroponic experiments, root hairs of the backcrossed lines with large rhizosheaths were more tolerant of Al(3+) toxicity than the backcrossed lines with small rhizosheaths. We conclude that greater Al(3+) tolerance of root hairs underlies the larger rhizosheath of wheat grown on acid soil. Tolerance of the root hairs to Al(3+) was largely independent of the TaALMT1 gene which suggests that different genes encode the Al(3+) tolerance of root hairs. The maintenance of longer root hairs in acid soils is important for the efficient uptake of water and nutrients. © 2012 The Authors. New Phytologist © 2012 New Phytologist Trust.

Kinetics of DCE and VC mineralization under methanogenic and Fe(III)- reducing conditions

USGS Publications Warehouse

Bradley, P.M.; Chapelle, F.H.

1997-01-01

The kinetics of anaerobic mineralization of DCE and VC under mathanogenic and Fe(III)-reducing conditions as a function of dissolved contaminant concentration were evaluated. Microorganisms indigenous to creek bed sediments, where groundwater contaminated with chlorinated ethenes continuously discharges, demonstrated significant mineralization of DCE and VC under methanogenic and Fe(III)- reducing conditions. Over 37 days, the recovery of [1,214C]VC radioactivity as 14CO2 ranged from 5% to 44% and from 8% to 100% under methanogenic and Fe(III)-reducing conditions, respectively. The recovery of [1,2-14C]DCE radioactivity as 14CO2 ranged from 4% to 14% and did not vary significantly between methanogenic and Fe(III)reducing conditions. VC mineralization was described by Michaelis- Menten kinetics. Under methanogenic conditions, V(max) was 0.19 ?? 0.01 ??mol L-1 d-1 and the half-saturation constant, k(m), was 7.6 ?? 1.7 ??M. Under Fe(III)-reducing conditions, V(max) was 0.76 ?? 0.07 ??mol L-1 d-1 and k(m) was 1.3 ?? 0.5 ??M. In contrast, DCE mineralization could be described by first-order kinetics. The first-order degradation rate constant for DCE mineralization was 0.6 ?? 0.2% d-1 under methanogenic and Fe(III)-reducing conditions. The results indicate that the kinetics of chlorinated ethane mineralization can vary significantly with the specific contaminant and the predominant redox conditions under which mineralization occurs.

Insights into the molecular mechanism of tolerance to carboxylic acid amide (CAA) fungicides in Pythium aphanidermatum.

PubMed

Blum, Mathias; Gisi, Ulrich

2012-08-01

Tolerance to the oomycete-specific carboxylic acid amide (CAA) fungicides is a poorly understood mechanism in Pythium species. The root-rot and damping-off causative agent Pythium aphanidermatum and the CAA fungicide mandipropamid (MPD) were used to investigate the molecular basis of CAA tolerance. Five genes putatively involved in carbohydrate synthesis were identified and characterised: one chitin synthase gene, PaChs, and four cellulose synthase genes PaCesA1 to PaCesA4, of which PaCesA3 encodes the MPD target enzyme. These genes were differentially expressed throughout the life cycle of P. aphanidermatum. Mycelium treated with MPD concentrations slightly affecting mycelial growth did not cause a change in PaCesA3 expression nor a strong upregulation of PaCesA homologues. The high tolerance level of P. aphanidermatum and the lack of PaCesA upregulation imply that MPD tolerance is the result of a specific amino acid configuration in the cellulose synthase 3 (CesA3) target enzyme. Indeed, P. aphanidermatum displays the amino acid L1109 which is also associated with MPD resistance in artificial mutants of Phytophthora species. It is concluded that MPD tolerance in P. aphanidermatum is not caused by compensatory mechanisms but most likely by an inherent target-site configuration in PaCesA3 that hinders MPD binding to the enzyme pocket. Copyright © 2012 Society of Chemical Industry.

Oxalic acid overproduction by copper-tolerant brown-rot basidiomycetes on southern yellow pine treated with copper-based preservatives

Treesearch

Carol A. Clausen; Frederick Green

2003-01-01

Accumulation of oxalic acid (OA) by brown-rot fungi and precipitation of copper oxalate crystals in wood decayed by copper-tolerant decay fungi has implicated OA in the mechanism of copper tolerance. Understanding the role of OA in copper tolerance is important due to an increasing reliance on copper-based wood preservatives. In this study, four copper-tolerant brown-...

Methanogenic Hydrocarbon Degradation: Evidence from Field and Laboratory Studies.

PubMed

Jiménez, Núria; Richnow, Hans H; Vogt, Carsten; Treude, Tina; Krüger, Martin

2016-01-01

Microbial transformation of hydrocarbons to methane is an environmentally relevant process taking place in a wide variety of electron acceptor-depleted habitats, from oil reservoirs and coal deposits to contaminated groundwater and deep sediments. Methanogenic hydrocarbon degradation is considered to be a major process in reservoir degradation and one of the main processes responsible for the formation of heavy oil deposits and oil sands. In the absence of external electron acceptors such as oxygen, nitrate, sulfate or Fe(III), fermentation and methanogenesis become the dominant microbial metabolisms. The major end product under these conditions is methane, and the only electron acceptor necessary to sustain the intermediate steps in this process is CO2, which is itself a net product of the overall reaction. We are summarizing the state of the art and recent advances in methanogenic hydrocarbon degradation research. Both the key microbial groups involved as well as metabolic pathways are described, and we discuss the novel insights into methanogenic hydrocarbon-degrading populations studied in laboratory as well as environmental systems enabled by novel cultivation-based and molecular approaches. Their possible implications on energy resources, bioremediation of contaminated sites, deep-biosphere research, and consequences for atmospheric composition and ultimately climate change are also addressed. © 2016 S. Karger AG, Basel.

Molecular diversity and tools for deciphering the methanogen community structure and diversity in freshwater sediments.

PubMed

Chaudhary, Prem Prashant; Brablcová, Lenka; Buriánková, Iva; Rulík, Martin

2013-09-01

Methanogenic archaeal communities existing in freshwater sediments are responsible for approximately 50 % of the total global emission of methane. This process contributes significantly to global warming and, hence, necessitates interventional control measures to limit its emission. Unfortunately, the diversity and functional interactions of methanogenic populations occurring in these habitats are yet to be fully characterized. Considering several disadvantages of conventional culture-based methodologies, in recent years, impetus is given to molecular biology approaches to determine the community structure of freshwater sedimentary methanogenic archaea. 16S rRNA and methyl coenzyme M reductase (mcrA) gene-based cloning techniques are the first choice for this purpose. In addition, electrophoresis-based (denaturing gradient gel electrophoresis, temperature gradient gel electrophoresis, and terminal restriction fragment length polymorphism) and quantitative real-time polymerase chain reaction techniques have also found extensive applications. These techniques are highly sensitive, rapid, and reliable as compared to traditional culture-dependent approaches. Molecular diversity studies revealed the dominance of the orders Methanomicrobiales and Methanosarcinales of methanogens in freshwater sediments. The present review discusses in detail the status of the diversity of methanogens and the molecular approaches applied in this area of research.

Shifts in methanogen community structure and function across a coastal marsh transect: effects of exotic Spartina alterniflora invasion

PubMed Central

Yuan, Junji; Ding, Weixin; Liu, Deyan; Kang, Hojeong; Xiang, Jian; Lin, Yongxin

2016-01-01

Invasion of Spartina alterniflora in coastal areas of China increased methane (CH4) emissions. To elucidate the underlying mechanisms, we measured CH4 production potential, methanogen community structure and biogeochemical factors along a coastal wetland transect comprised of five habitat regions: open water, bare tidal flat, invasive S. alterniflora marsh and native Suaeda salsa and Phragmites australis marshes. CH4 production potential in S. alterniflora marsh was 10 times higher than that in other regions, and it was significantly correlated with soil organic carbon, dissolved organic carbon and trimethylamine concentrations, but was not correlated with acetate or formate concentrations. Although the diversity of methanogens was lowest in S. alterniflora marsh, invasion increased methanogen abundance by 3.48-fold, compared with native S. salsa and P. australis marshes due to increase of facultative Methanosarcinaceae rather than acetotrophic and hydrogenotrophic methanogens. Ordination analyses suggested that trimethylamine was the primary factor regulating shift in methanogen community structure. Addition of trimethylamine increased CH4 production rates by 1255-fold but only by 5.61- and 11.4-fold for acetate and H2/CO2, respectively. S. alterniflora invasion elevated concentration of non-competitive trimethylamine, and shifted methanogen community from acetotrophic to facultative methanogens, which together facilitated increased CH4 production potential. PMID:26728134

Safety and tolerability of the γ-secretase inhibitor avagacestat in a phase 2 study of mild to moderate Alzheimer disease.

PubMed

Coric, Vladimir; van Dyck, Christopher H; Salloway, Stephen; Andreasen, Niels; Brody, Mark; Richter, Ralph W; Soininen, Hilkka; Thein, Stephen; Shiovitz, Thomas; Pilcher, Gary; Colby, Susan; Rollin, Linda; Dockens, Randy; Pachai, Chahin; Portelius, Erik; Andreasson, Ulf; Blennow, Kaj; Soares, Holly; Albright, Charles; Feldman, Howard H; Berman, Robert M

2012-11-01

To assess the safety, tolerability, and pharmacokinetic and pharmacodynamic effects of the -secretase inhibitor avagacestat in patients with mild to moderate Alzheimer disease (AD). Randomized, double-blind, placebo-controlled,24-week phase 2 study. Global, multicenter trial. A total of 209 outpatients with mild to moderate AD were randomized into the double-blind treatment phase. The median age of the patients was 75 years,58.9% were APOE ε4 carriers, and baseline measures of disease severity were similar among groups. Avagacestat, 25, 50, 100, or 125 mg daily,or placebo administered orally daily. Safety and tolerability of avagacestat. Discontinuation rates for the 25-mg and 50-mg doses of avagacestat were comparable with placebo but were higher in the 100-mg and 125-mg dose groups.Trends for worsening cognition, as measured by change from baseline Alzheimer Disease Assessment Scale cognitive subscale score, were observed in the 100-mg and125-mg dose groups. Treatment-emergent serious adverse events were similar across placebo and treatment groups. The most common reason for discontinuation was adverse events, predominantly gastrointestinal anddermatologic. Other adverse events occurring more frequentlyin patients undergoing treatment included reversibleglycosuria (without associated serum glucose changes), nonmelanoma skin cancer, and asymptomaticmagnetic resonance imaging findings. Exploratory cerebrospinal fluid amyloid isoforms and tau biomarker analysis demonstrated dose-dependent but not statistically significant reductions in a small subset of patients. Avagacestat dosed at 25 and 50 mg daily was relatively well tolerated and had low discontinuation rates. The 100-mg and 125-mg dose arms were poorly tolerated with trends for cognitive worsening. Exploratory cerebrospinal fluid biomarker substudies provide preliminary support for -secretase target engagement,but additional studies are warranted to better characterize pharmacodynamic effects at the 25- and

Acid-tolerant microaerophilic Fe(II)-oxidizing bacteria promote Fe(III)-accumulation in a fen.

PubMed

Lüdecke, Claudia; Reiche, Marco; Eusterhues, Karin; Nietzsche, Sandor; Küsel, Kirsten

2010-10-01

The ecological importance of Fe(II)-oxidizing bacteria (FeOB) at circumneutral pH is often masked in the presence of O(2) where rapid chemical oxidation of Fe(II) predominates. This study addresses the abundance, diversity and activity of microaerophilic FeOB in an acidic fen (pH ∼ 5) located in northern Bavaria, Germany. Mean O(2) penetration depth reached 16 cm where the highest dissolved Fe(II) concentrations (up to 140 µM) were present in soil water. Acid-tolerant FeOB cultivated in gradient tubes were most abundant (10(6) cells g(-1) peat) at the 10-20 cm depth interval. A stable enrichment culture was active at up to 29% O(2) saturation and Fe(III) accumulated 1.6 times faster than in abiotic controls. An acid-tolerant, microaerophilic isolate (strain CL21) was obtained which was closely related to the neutrophilic, lithoautotrophic FeOB Sideroxydans lithotrophicus strain LD-1. CL21 oxidized Fe(II) between pH 4 and 6.0, and produced nanoscale-goethites with a clearly lower mean coherence length (7 nm) perpendicular to the (110) plane than those formed abiotically (10 nm). Our results suggest that an acid-tolerant population of FeOB is thriving at redox interfaces formed by diffusion-limited O(2) transport in acidic peatlands. Furthermore, this well-adapted population is successfully competing with chemical oxidation and thereby playing an important role in the microbial iron cycle. © 2010 Society for Applied Microbiology and Blackwell Publishing Ltd.

Biofilm-forming bacteria with varying tolerance to peracetic acid from a paper machine.

PubMed

Rasimus, Stiina; Kolari, Marko; Rita, Hannu; Hoornstra, Douwe; Salkinoja-Salonen, Mirja

2011-09-01

Biofilms cause runnability problems in paper machines and are therefore controlled with biocides. Peracetic acid is usually effective in preventing bulky biofilms. This study investigated the microbiological status of a paper machine where low concentrations (≤ 15 ppm active ingredient) of peracetic acid had been used for several years. The paper machine contained a low amount of biofilms. Biofilm-forming bacteria from this environment were isolated and characterized by 16S rRNA gene sequencing, whole-cell fatty acid analysis, biochemical tests, and DNA fingerprinting. Seventy-five percent of the isolates were identified as members of the subclades Sphingomonas trueperi and S. aquatilis, and the others as species of the genera Burkholderia (B. cepacia complex), Methylobacterium, and Rhizobium. Although the isolation media were suitable for the common paper machine biofoulers Deinococcus, Meiothermus, and Pseudoxanthomonas, none of these were found, indicating that peracetic acid had prevented their growth. Spontaneous, irreversible loss of the ability to form biofilm was observed during subculturing of certain isolates of the subclade S. trueperi. The Sphingomonas isolates formed monoculture biofilms that tolerated peracetic acid at concentrations (10 ppm active ingredient) used for antifouling in paper machines. High pH and low conductivity of the process waters favored the peracetic acid tolerance of Sphingomonas sp. biofilms. This appears to be the first report on sphingomonads as biofilm formers in warm water using industries.

Community Composition and Density of Methanogens in the Foregut of the Tammar Wallaby (Macropus eugenii)▿

PubMed Central

Evans, Paul N.; Hinds, Lyn A.; Sly, Lindsay I.; McSweeney, Christopher S.; Morrison, Mark; Wright, André-Denis G.

2009-01-01

The composition of the methanogenic archaeal community in the foregut contents of Tammar wallabies (Macropus eugenii) was studied using 16S rRNA and methyl coenzyme reductase subunit A (mcrA) gene clone libraries. Methanogens belonging to the Methanobacteriales and a well-supported cluster of uncultivated archaeon sequences previously observed in the ovine and bovine rumens were found. Methanogen densities ranged from 7.0 × 105 and 3.9 × 106 cells per gram of wet weight. PMID:19218421

Effect of dietary fiber on the methanogen community in the hindgut of Lantang gilts.

PubMed

Cao, Z; Liang, J B; Liao, X D; Wright, A D G; Wu, Y B; Yu, B

2016-10-01

The primary objective of this study was to investigate the effect of dietary fiber on methanogenic diversity and community composition in the hindgut of indigenous Chinese Lantang gilts to explain the unexpected findings reported earlier that Lantang gilts fed low-fiber diet (LFD) produced more methane than those fed high-fiber diet (HFD). In total, 12 Lantang gilts (58.7±0.37 kg) were randomly divided into two dietary groups (six replicates (pigs) per group) and fed either LFD (NDF=201.46 g/kg) or HFD (NDF=329.70 g/kg). Wheat bran was the main source of fiber for the LFD, whereas ground rice hull (mixture of rice hull and rice bran) was used for the HFD. Results showed that the methanogens in the hindgut of Lantang gilts belonged to four known species (Methanobrevibacter ruminantium, Methanobrevibacter wolinii, Methanosphaera stadtmanae and Methanobrevibacter smithii), with about 89% of the methanogens belonging to the genus Methanobrevibacter. The 16S ribosomal RNA (rRNA) gene copies of Methanobrevibacter were more than three times higher (P0.05) was observed in 16S rRNA gene copies of Fibrobacter succinogenes between the two dietary groups, and 18S rRNA gene copies of anaerobic fungi in gilts fed LFD were lower than (P<0.05) those fed HFD. To better explain the effect of different fiber source on the methanogen community, a follow-up in vitro fermentation using a factorial design comprised of two inocula (prepared from hindgut content of gilts fed two diets differing in their dietary fiber)×four substrates (LFD, HFD, wheat bran, ground rice hull) was conducted. Results of the in vitro fermentation confirmed that the predominant methanogens belonged to the genus of Methanobrevibacter, and about 23% methanogens was found to be distantly related (90%) to Thermogymnomonas acidicola. In vitro fermentation also seems to suggest that fiber source did change the methanogens community. Although the density of Methanobrevibacter species was positively correlated with CH

The acid tolerance response and pH adaptation of Enterococcus faecalis in extract of lime Citrus aurantiifolia from Aceh Indonesia.

PubMed

Mubarak, Zaki; Soraya, Cut

2018-01-01

Background:  The objective of the present study was to evaluate the acid tolerance response and pH adaptation when Enterococcus faecalis interacted with extract of lime ( Citrus aurant iifolia ). Methods : We used E. faecalis ATCC 29212 and lime extract from Aceh, Indonesia. The microbe was analyzed for its pH adaptation, acid tolerance response, and adhesion assay using a light microscope with a magnification of x1000. Further, statistical tests were performed to analyze both correlation and significance of the acid tolerance and pH adaptation as well as the interaction activity. Results : E. faecalis was able to adapt to a very acidic environment (pH 2.9), which was characterized by an increase in its pH (reaching 4.2) at all concentrations of the lime extract (p < 0.05). E. faecalis was also able to provide acid tolerance response to lime extract based on spectrophotometric data (595 nm) (p < 0.05). Also, the interaction activity of E. faecalis in different concentrations of lime extract was relatively stable within 6 up to 12 hours (p < 0.05), but it became unstable within 24-72 hours (p > 0.05) based on the mass profiles of its interaction activity. Conclusions : E. faecalis can adapt to acidic environments (pH 2.9-4.2); it is also able to tolerate acid generated by Citrus auranti ifolia extract, revealing a stable interaction in the first 6-12 hours.

An acid-tolerant ammonia-oxidizing γ-proteobacterium from soil

PubMed Central

Hayatsu, Masahito; Tago, Kanako; Uchiyama, Ikuo; Toyoda, Atsushi; Wang, Yong; Shimomura, Yumi; Okubo, Takashi; Kurisu, Futoshi; Hirono, Yuhei; Nonaka, Kunihiko; Akiyama, Hiroko; Itoh, Takehiko; Takami, Hideto

2017-01-01

Nitrification, the microbial oxidation of ammonia to nitrate via nitrite, occurs in a wide range of acidic soils. However, the ammonia-oxidizing bacteria (AOB) that have been isolated from soil to date are acid-sensitive. Here we report the isolation and characterization of an acid-adapted AOB from an acidic agricultural soil. The isolated AOB, strain TAO100, is classified within the Gammaproteobacteria based on phylogenetic characteristics. TAO100 can grow in the pH range of 5–7.5 and survive in highly acidic conditions until pH 2 by forming cell aggregates. Whereas all known gammaproteobacterial AOB (γ-AOB) species, which have been isolated from marine and saline aquatic environments, are halophiles, TAO100 is not phenotypically halophilic. Thus, TAO100 represents the first soil-originated and non-halophilic γ-AOB. The TAO100 genome is considerably smaller than those of other γ-AOB and lacks several genes associated with salt tolerance which are unnecessary for survival in soil. The ammonia monooxygenase subunit A gene of TAO100 and its transcript are higher in abundance than those of ammonia-oxidizing archaea and betaproteobacterial AOB in the strongly acidic soil. These results indicate that TAO100 plays an important role in the nitrification of acidic soils. Based on these results, we propose TAO100 as a novel species of a new genus, Candidatus Nitrosoglobus terrae. PMID:28072419

An acid-tolerant ammonia-oxidizing γ-proteobacterium from soil.

PubMed

Hayatsu, Masahito; Tago, Kanako; Uchiyama, Ikuo; Toyoda, Atsushi; Wang, Yong; Shimomura, Yumi; Okubo, Takashi; Kurisu, Futoshi; Hirono, Yuhei; Nonaka, Kunihiko; Akiyama, Hiroko; Itoh, Takehiko; Takami, Hideto

2017-05-01

Nitrification, the microbial oxidation of ammonia to nitrate via nitrite, occurs in a wide range of acidic soils. However, the ammonia-oxidizing bacteria (AOB) that have been isolated from soil to date are acid-sensitive. Here we report the isolation and characterization of an acid-adapted AOB from an acidic agricultural soil. The isolated AOB, strain TAO100, is classified within the Gammaproteobacteria based on phylogenetic characteristics. TAO100 can grow in the pH range of 5-7.5 and survive in highly acidic conditions until pH 2 by forming cell aggregates. Whereas all known gammaproteobacterial AOB (γ-AOB) species, which have been isolated from marine and saline aquatic environments, are halophiles, TAO100 is not phenotypically halophilic. Thus, TAO100 represents the first soil-originated and non-halophilic γ-AOB. The TAO100 genome is considerably smaller than those of other γ-AOB and lacks several genes associated with salt tolerance which are unnecessary for survival in soil. The ammonia monooxygenase subunit A gene of TAO100 and its transcript are higher in abundance than those of ammonia-oxidizing archaea and betaproteobacterial AOB in the strongly acidic soil. These results indicate that TAO100 plays an important role in the nitrification of acidic soils. Based on these results, we propose TAO100 as a novel species of a new genus, Candidatus Nitrosoglobus terrae.

[The effect of reamberin and alpha-lipoic acid on the tolerance to acute cerebral ischemia in experimental diabetes mellitus].

PubMed

Volchegorskii, I A; Miroshnichenko, I Yu; Rassokhina, L M; Faizullin, R M

To study an effect of reamberin and α-lipoic acid (α-LA) on the tolerance of mice with experimental diabetes mellitus (DM) to acute cerebrovascular accident (ACVA) in mice experiments. The authors studied mice with alloxan diabetes and subtotal and total brain ischemia. In additional experimental series, an effect of reamberin and α-lipoic acid on the tolerance to acute hypoxic hypoxia and intensity of hyperglycemia in experimental DM was studied. The increased vulnerability of animals to ACVA due to hyperglycemia and increased sensitivity to acute hypoxic hypoxia was established. Reamberin and α-lipoic acid administered for 14 days in doses, which are equivalent to therapeutic range in humans, enhance the tolerance to ACVA and acute hypoxic hypoxia in mice with alloxan diabetes. These medications also decrease the intensity of hyperglycemia during concurrent insulin replacement therapy. The increased tolerance to ACVA in mice with alloxan diabetes caused by reamberin and alpha-lipoic acid is associated with an antihypoxic effect of these medications and does not depend on their effect on the intensity of hyperglycemia. Reamberin outperformed α-lipoic acid in the antihypoxic activity, protection against ACVA and the rate of onset of glucose reducing effect in experimental diabetes mellitus.

Quantitative sensory testing and pain tolerance in patients with mild to moderate Alzheimer disease compared to healthy control subjects.

PubMed

Jensen-Dahm, Christina; Werner, Mads U; Dahl, Jørgen B; Jensen, Troels Staehelin; Ballegaard, Martin; Hejl, Anne-Mette; Waldemar, Gunhild

2014-08-01

Patients with Alzheimer disease (AD) report pain less frequently than their cognitively intact peers. It has been hypothesized that pain processing is altered in AD. The aim of this study was to investigate agreement and reliability of 3 pain sensitivity tests and to examine pain threshold and tolerance in patients with AD. We examined 29 patients with mild to moderate AD and 29 age- and gender-matched healthy control subjects with quantitative sensory testing, ie, assessments of detection threshold (warmth detection threshold [WDT]) and pain threshold (heat pain threshold [HPT], pressure algometry, cold pressor test), and assessments of tolerance (pressure algometry, cold pressor test). All procedures were done twice on day 1, 1 hour apart, and repeated on day 2. We found no difference between groups for WDT (patient vs control subjects: mean [95% confidence interval]: 35.5°C [33.4°C to 37.6°C] vs 35.4°C [34.3°C to 36.5°C], P=.8) or HPT (41.2°C [40.0°C to 42.4°C] vs 42.3°C [41.1°C to 43.5°C], P=.24). We observed comparable thresholds for pressure algometry (median [25% to 75% interquartile range]: 120 kPa [100 to 142 kPa] vs 131 kPa [113 to 192 kPa], P=.10), but significantly lower tolerance in AD patients (213 kPa [188 to 306 kPa] vs 289 kPa [262 to 360 kPa], P=.008). No differences were found for the cold pressor test. The study demonstrated good replicability of the sensory testing data with comparable data variability, for both groups, which supports the use of these methods in studies of patients with mild to moderate AD. Contrary to previous studies, we observed a reduced pain tolerance in patients with mild to moderate AD, which suggests that the reduced report of pain cannot be explained by reduced processing of painful stimuli. Copyright © 2014 International Association for the Study of Pain. Published by Elsevier B.V. All rights reserved.

Community structure of methanogenic archaea and methane production associated with compost-treated tropical rice-field soil.

PubMed

Singh, Alpana; Singh, Ram S; Upadhyay, Siddh N; Joshi, Chaitanya G; Tripathi, Ajay K; Dubey, Suresh K

2012-10-01

The diversity and density of methanogenic archaea and methane production were investigated ex situ at different growth stages of rice plant cultivated in compost-treated tropical rice fields. The qPCR analysis revealed variation in methanogens population from 3.40 × 10(6) to 1.11 × 10(7)  copies g(-1)  dws, in the year 2009 and 4.37 × 10(6) to 1.36 × 10(7)  copies g(-1)  dws in the year 2010. Apart from methanogens, a large number of bacterial (9.60 × 10(9) -1.44 × 10(10)  copies g(-1)  dws) and archaeal (7.13 × 10(7) -3.02 × 10(8)  copies g(-1)  dws) communities were also associated with methanogenesis. Methanogen population size varied in the order: flowering > ripening > tillering > postharvest > preplantation stage. The RFLP-based 16S rRNA gene-targeted phylogenetic analysis showed that clones were closely related to diverse group of methanogens comprising members of Methanomicrobiaceae, Methanosarcinaceae, Methanosaetaceae and RC I. Laboratory incubation studies revealed higher amount of cumulative CH(4) at the flowering stage. The integration of methanogenic community structure and CH(4) production potential of soil resulted in a better understanding of the dynamics of CH(4) production in organically treated rice-field soil. The hypothesis that the stages of plant development influence the methanogenic community structure leading to temporal variation in the CH(4) production has been successfully tested. © 2012 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.

Computational Modeling of Fluctuations in Energy and Metabolic Pathways of Methanogenic Archaea

DOE Office of Scientific and Technical Information (OSTI.GOV)

Luthey-Schulten, Zaida

The methanogenic archaea, anaerobic microbes that convert CO2 and H2 and/or other small organic fermentation products into methane, play an unusually large role in the global carbon cycle. As they perform the final step in the anaerobic breakdown of biomass, methanogens are a biogenic source of an estimated one billion tons methane each year. Depending on the location, produced methane can be considered as either a greenhouse gas (agricultural byproduct), sequestered carbon storage (methane hydrate deposits), or a potential energy source (organic wastewater treatment). These microbes therefore represent an important target for biotechnology applications. Computational models of methanogens with predictivemore » power are useful aids in the adaptation of methanogenic systems, but need to connect processes of wide-ranging time and length scales. In this project, we developed several computational methodologies for modeling the dynamic behavior of entire cells that connects stochastic reaction-diffusion dynamics of individual biochemical pathways with genome-scale modeling of metabolic networks. While each of these techniques were in the realm of well-defined computational methods, here we integrated them to develop several entirely new approaches to systems biology. The first scientific aim of the project was to model how noise in a biochemical pathway propagates into cellular phenotypes. Genetic circuits have been optimized by evolution to regulate molecular processes despite stochastic noise, but the effect of such noise on a cellular biochemical networks is currently unknown. An integrated stochastic/systems model of Escherichia coli species was created to analyze how noise in protein expression gives—and therefore noise in metabolic fluxes—gives rise to multiple cellular phenotype in isogenic population. After the initial work developing and validating methods that allow characterization of the heterogeneity in the model organism E. coli, the project

Evaluation of methanogenic treatment of TMAH (tetra-methyl ammonium hydroxide) in a full-scale TFT-LCD wastewater treatment process.

PubMed

Hu, T H; Whang, L M; Lei, C N; Chen, C F; Chiang, T Y; Lin, L B; Chen, H W; Liu, P W G; Cheng, S S

2010-01-01

This study evaluated TMAH biodegradation under methanogenic conditions. Under methanogenic conditions, a sludge from a full-scale UASB treating TFT-LCD wastewater was able to degrade 2,000 mg/L of TMAH within 10 h and attained a specific degradation rate of 19.2 mgTMAH/gVSS-h. Furthermore, several chemicals including some surfactants, DMSO, and sulfate were examined for their potential inhibitory effects on TMAH biodegradation under methanogenic conditions. The results indicated that surfactant S1 (up to 2%) and DMSO (up to 1,000 mg/L) presented negligible inhibitory effects on TMAH degradation, while surfactant S2 (0.2-1%) might inhibit methanogenic reaction without any TMAH degradation for 3-5 h. At sulfate concentrations higher than 300 mg/L, a complete inhibition of methanogenic reaction and TMAH biodegradation was observed. Results from cloning and sequencing of archaeal 16S rRNA gene fragments showed that Methanosarcina barkeri and Methanosarcina mazei were the dominant methanogens in the UASB treating TMAH-containing TFT-LCD wastewater.

Effects of the acid-tolerant engineered bacterial strain Megasphaera elsdenii H6F32 on ruminal pH and the lactic acid concentration of simulated rumen acidosis in vitro.

PubMed

Long, M; Feng, W J; Li, P; Zhang, Y; He, R X; Yu, L H; He, J B; Jing, W Y; Li, Y M; Wang, Z; Liu, G W

2014-02-01

The aim of this study was to examine the effects of the acid-tolerant engineered bacterial strain Megasphaera elsdenii H6F32 (M. elsdenii H6F32) on ruminal pH and the lactic acid concentrations in simulated rumen acidosis conditions in vitro. A mixed culture of ruminal bacteria, buffer, and primarily degradable substrates was inoculated with equal numbers of M. elsdenii H6 or M. elsdenii H6F32. The pH and lactic acid concentrations in the mixed culture were determined at 0, 2, 4, 6, 8, 10, 12, 14, 16, and 18 h of incubation. Acid-tolerant M. elsdenii H6F32 reduced the accumulation of lactic acid and increased the pH value. These results indicate that acid-tolerant M. elsdenii H6F32 could be a potential candidate for preventing rumen acidosis. Copyright © 2013 Elsevier Ltd. All rights reserved.

Expression of Mitochondrial Cytochrome C Oxidase Chaperone Gene (COX20) Improves Tolerance to Weak Acid and Oxidative Stress during Yeast Fermentation

PubMed Central

Kumar, Vinod; Hart, Andrew J.; Keerthiraju, Ethiraju R.; Waldron, Paul R.; Tucker, Gregory A.; Greetham, Darren

2015-01-01

Introduction Saccharomyces cerevisiae is the micro-organism of choice for the conversion of fermentable sugars released by the pre-treatment of lignocellulosic material into bioethanol. Pre-treatment of lignocellulosic material releases acetic acid and previous work identified a cytochrome oxidase chaperone gene (COX20) which was significantly up-regulated in yeast cells in the presence of acetic acid. Results A Δcox20 strain was sensitive to the presence of acetic acid compared with the background strain. Overexpressing COX20 using a tetracycline-regulatable expression vector system in a Δcox20 strain, resulted in tolerance to the presence of acetic acid and tolerance could be ablated with addition of tetracycline. Assays also revealed that overexpression improved tolerance to the presence of hydrogen peroxide-induced oxidative stress. Conclusion This is a study which has utilised tetracycline-regulated protein expression in a fermentation system, which was characterised by improved (or enhanced) tolerance to acetic acid and oxidative stress. PMID:26427054

40 CFR 180.1178 - Formic acid; exemption from the requirement of a tolerance.

Code of Federal Regulations, 2013 CFR

2013-07-01

... pesticide formic acid is exempted from the requirement of a tolerance in or on honey and honeycomb when used to control tracheal mites and suppress varroa mites in bee colonies, and applied in accordance with...

40 CFR 180.1178 - Formic acid; exemption from the requirement of a tolerance.

Code of Federal Regulations, 2012 CFR

2012-07-01

... pesticide formic acid is exempted from the requirement of a tolerance in or on honey and honeycomb when used to control tracheal mites and suppress varroa mites in bee colonies, and applied in accordance with...

40 CFR 180.1178 - Formic acid; exemption from the requirement of a tolerance.

Code of Federal Regulations, 2011 CFR

2011-07-01

... pesticide formic acid is exempted from the requirement of a tolerance in or on honey and honeycomb when used to control tracheal mites and suppress varroa mites in bee colonies, and applied in accordance with...

40 CFR 180.1178 - Formic acid; exemption from the requirement of a tolerance.

Code of Federal Regulations, 2010 CFR

2010-07-01

... pesticide formic acid is exempted from the requirement of a tolerance in or on honey and honeycomb when used to control tracheal mites and suppress varroa mites in bee colonies, and applied in accordance with...

40 CFR 180.1178 - Formic acid; exemption from the requirement of a tolerance.

Code of Federal Regulations, 2014 CFR

2014-07-01

... pesticide formic acid is exempted from the requirement of a tolerance in or on honey and honeycomb when used to control tracheal mites and suppress varroa mites in bee colonies, and applied in accordance with...

GID1 modulates stomatal response and submergence tolerance involving abscisic acid and gibberellic acid signaling in rice.

PubMed

Du, Hao; Chang, Yu; Huang, Fei; Xiong, Lizhong

2015-11-01

Plant responses to abiotic stresses are coordinated by arrays of growth and developmental programs. Gibberellic acid (GA) and abscisic acid (ABA) play critical roles in the developmental programs and environmental responses, respectively, through complex signaling and metabolism networks. However, crosstalk between the two phytohormones in stress responses remains largely unknown. In this study, we report that GIBBERELLIN-INSENSITIVE DWARF 1 (GID1), a soluble receptor for GA, regulates stomatal development and patterning in rice (Oryza sativa L.). The gid1 mutant showed impaired biosynthesis of endogenous ABA under drought stress conditions, but it exhibited enhanced sensitivity to exogenous ABA. Scanning electron microscope and infrared thermal image analysis indicated an increase in the stomatal conductance in the gid1 mutant under drought conditions. Interestingly, the gid1 mutant had increased levels of chlorophyll and carbohydrates under submergence conditions, and showed enhanced reactive oxygen species (ROS)-scavenging ability and submergence tolerance compared with the wild-type. Further analyses suggested that the function of GID1 in submergence responses is partially dependent on ABA, and GA signaling by GID1 is involved in submergence tolerance by modulating carbohydrate consumption. Taken together, these findings suggest GID1 plays distinct roles in stomatal response and submergence tolerance through both the ABA and GA signaling pathways in rice. © 2014 Institute of Botany, Chinese Academy of Sciences.

Use of a Hierarchical Oligonucleotide Primer Extension Approach for Multiplexed Relative Abundance Analysis of Methanogens in Anaerobic Digestion Systems

PubMed Central

Chuang, Hui-Ping; Hsu, Mao-Hsuan; Chen, Wei-Yu

2013-01-01

In this study, we established a rapid multiplex method to detect the relative abundances of amplified 16S rRNA genes from known cultivatable methanogens at hierarchical specificities in anaerobic digestion systems treating industrial wastewater and sewage sludge. The method was based on the hierarchical oligonucleotide primer extension (HOPE) technique and combined with a set of 27 primers designed to target the total archaeal populations and methanogens from 22 genera within 4 taxonomic orders. After optimization for their specificities and detection sensitivity under the conditions of multiple single-nucleotide primer extension reactions, the HOPE approach was applied to analyze the methanogens in 19 consortium samples from 7 anaerobic treatment systems (i.e., 513 reactions). Among the samples, the methanogen populations detected with order-level primers accounted for >77.2% of the PCR-amplified 16S rRNA genes detected using an Archaea-specific primer. The archaeal communities typically consisted of 2 to 7 known methanogen genera within the Methanobacteriales, Methanomicrobiales, and Methanosarcinales and displayed population dynamic and spatial distributions in anaerobic reactor operations. Principal component analysis of the HOPE data further showed that the methanogen communities could be clustered into 3 distinctive groups, in accordance with the distribution of the Methanosaeta, Methanolinea, and Methanomethylovorans, respectively. This finding suggested that in addition to acetotrophic and hydrogenotrophic methanogens, the methylotrophic methanogens might play a key role in the anaerobic treatment of industrial wastewater. Overall, the results demonstrated that the HOPE approach is a specific, rapid, and multiplexing platform to determine the relative abundances of targeted methanogens in PCR-amplified 16S rRNA gene products. PMID:24077716

Molecular Analysis of Methanogen Richness in Landfill and Marshland Targeting 16S rDNA Sequences

PubMed Central

Yadav, Shailendra; Kundu, Sharbadeb; Ghosh, Sankar K.; Maitra, S. S.

2015-01-01

Methanogens, a key contributor in global carbon cycling, methane emission, and alternative energy production, generate methane gas via anaerobic digestion of organic matter. The methane emission potential depends upon methanogenic diversity and activity. Since they are anaerobes and difficult to isolate and culture, their diversity present in the landfill sites of Delhi and marshlands of Southern Assam, India, was analyzed using molecular techniques like 16S rDNA sequencing, DGGE, and qPCR. The sequencing results indicated the presence of methanogens belonging to the seventh order and also the order Methanomicrobiales in the Ghazipur and Bhalsawa landfill sites of Delhi. Sequences, related to the phyla Crenarchaeota (thermophilic) and Thaumarchaeota (mesophilic), were detected from marshland sites of Southern Assam, India. Jaccard analysis of DGGE gel using Gel2K showed three main clusters depending on the number and similarity of band patterns. The copy number analysis of hydrogenotrophic methanogens using qPCR indicates higher abundance in landfill sites of Delhi as compared to the marshlands of Southern Assam. The knowledge about “methanogenic archaea composition” and “abundance” in the contrasting ecosystems like “landfill” and “marshland” may reorient our understanding of the Archaea inhabitants. This study could shed light on the relationship between methane-dynamics and the global warming process. PMID:26568700

Methanogenic degradation of lignin-derived monoaromatic compounds by microbial enrichments from rice paddy field soil.

PubMed

Kato, Souichiro; Chino, Kanako; Kamimura, Naofumi; Masai, Eiji; Yumoto, Isao; Kamagata, Yoichi

2015-09-24

Anaerobic degradation of lignin-derived aromatics is an important metabolism for carbon and nutrient cycles in soil environments. Although there are some studies on degradation of lignin-derived aromatics by nitrate- and sulfate-reducing bacteria, knowledge on their degradation under methanogenic conditions are quite limited. In this study, methanogenic microbial communities were enriched from rice paddy field soil with lignin-derived methoxylated monoaromatics (vanillate and syringate) and their degradation intermediates (protocatechuate, catechol, and gallate) as the sole carbon and energy sources. Archaeal community analysis disclosed that both aceticlastic (Methanosarcina sp.) and hydrogenotrophic (Methanoculleus sp. and Methanocella sp.) methanogens dominated in all of the enrichments. Bacterial community analysis revealed the dominance of acetogenic bacteria (Sporomusa spp.) only in the enrichments on the methoxylated aromatics, suggesting that Sporomusa spp. initially convert vanillate and syringate into protocatechuate and gallate, respectively, with acetogenesis via O-demethylation. As the putative ring-cleavage microbes, bacteria within the phylum Firmicutes were dominantly detected from all of the enrichments, while the dominant phylotypes were not identical between enrichments on vanillate/protocatechuate/catechol (family Peptococcaceae bacteria) and on syringate/gallate (family Ruminococcaceae bacteria). This study demonstrates the importance of cooperation among acetogens, ring-cleaving fermenters/syntrophs and aceticlastic/hydrogenotrophic methanogens for degradation of lignin-derived aromatics under methanogenic conditions.

Methanogenic degradation of lignin-derived monoaromatic compounds by microbial enrichments from rice paddy field soil

PubMed Central

Kato, Souichiro; Chino, Kanako; Kamimura, Naofumi; Masai, Eiji; Yumoto, Isao; Kamagata, Yoichi

2015-01-01

Anaerobic degradation of lignin-derived aromatics is an important metabolism for carbon and nutrient cycles in soil environments. Although there are some studies on degradation of lignin-derived aromatics by nitrate- and sulfate-reducing bacteria, knowledge on their degradation under methanogenic conditions are quite limited. In this study, methanogenic microbial communities were enriched from rice paddy field soil with lignin-derived methoxylated monoaromatics (vanillate and syringate) and their degradation intermediates (protocatechuate, catechol, and gallate) as the sole carbon and energy sources. Archaeal community analysis disclosed that both aceticlastic (Methanosarcina sp.) and hydrogenotrophic (Methanoculleus sp. and Methanocella sp.) methanogens dominated in all of the enrichments. Bacterial community analysis revealed the dominance of acetogenic bacteria (Sporomusa spp.) only in the enrichments on the methoxylated aromatics, suggesting that Sporomusa spp. initially convert vanillate and syringate into protocatechuate and gallate, respectively, with acetogenesis via O-demethylation. As the putative ring-cleavage microbes, bacteria within the phylum Firmicutes were dominantly detected from all of the enrichments, while the dominant phylotypes were not identical between enrichments on vanillate/protocatechuate/catechol (family Peptococcaceae bacteria) and on syringate/gallate (family Ruminococcaceae bacteria). This study demonstrates the importance of cooperation among acetogens, ring-cleaving fermenters/syntrophs and aceticlastic/hydrogenotrophic methanogens for degradation of lignin-derived aromatics under methanogenic conditions. PMID:26399549

Is aceticlastic methanogen composition in full-scale anaerobic processes related to acetate utilization capacity?

PubMed

Yilmaz, Vedat; Ince-Yilmaz, Ebru; Yilmazel, Yasemin Dilsad; Duran, Metin

2014-06-01

In this study, biomass samples were obtained from six municipal and nine industrial full-scale anaerobic processes to investigate whether the aceticlastic methanogen population composition is related to acetate utilization capacity and the nature of the wastewater treated, i.e. municipal sludge or industrial wastewater. Batch serum bottle tests were used to determine the specific acetate utilization rate (AUR), and a quantitative real-time polymerase chain reaction protocol was used to enumerate the acetate-utilizing Methanosaeta and Methanosarcina populations in the biomass samples. Methanosaeta was the dominant aceticlastic methanogen in all samples, except for one industrial wastewater-treating anaerobic process. However, Methanosarcina density in industrial biomass samples was higher than the Methanosarcina density in the municipal samples. The average AUR values of municipal and industrial wastewater treatment plant biomass samples were 10.49 and 10.65 mg CH3COO(-)/log(aceticlastic methanogen gene copy).d, respectively. One-way ANOVA test and principle component analysis showed that the acetate utilization capacities and aceticlastic methanogen community composition did not show statistically significant correlation among the municipal digesters and industrial wastewater-treating processes investigated.

Methanonatronarchaeum thermophilum gen. nov., sp. nov. and 'Candidatus Methanohalarchaeum thermophilum', extremely halo(natrono)philic methyl-reducing methanogens from hypersaline lakes comprising a new euryarchaeal class Methanonatronarchaeia classis nov.

PubMed

Sorokin, Dimitry Y; Merkel, Alexander Y; Abbas, Ben; Makarova, Kira S; Rijpstra, W Irene C; Koenen, M; Sinninghe Damsté, Jaap S; Galinski, Erwin A; Koonin, Eugene V; van Loosdrecht, Mark C M

2018-05-21

Methanogenic enrichments from hypersaline lakes at moderate thermophilic conditions have resulted in the cultivation of an unknown deep lineage of euryarchaeota related to the class Halobacteria. Eleven soda lake isolates and three salt lake enrichment cultures were methyl-reducing methanogens that utilize C1 methylated compounds as electron acceptors and H2 or formate as electron donors, but they were unable to grow on either substrates alone or to form methane from acetate. They are extreme halophiles, growing optimally at 4 M total Na + and the first representatives of methanogens employing the 'salt-in' osmoprotective mechanism. The salt lake subgroup is neutrophilic, whereas the soda lake isolates are obligate alkaliphiles, with an optimum around pH 9.5. Both grow optimally at 50 °C. The genetic diversity inside the two subgroups is very low, indicating that the soda and salt lake clusters consist of a single genetic species each. The phylogenetic distance between the two subgroups is in the range of distant genera, whereas the distance to other euryarchaea is below 83 % identity of the 16S rRNA gene. These isolates and enriched methanogens, together with closely related environmental clones from hypersaline habitats (the SA1 group), form a novel class-level clade in the phylum Euryarchaeota. On the basis of distinct phenotypic and genetic properties, the soda lake isolates are classified into a new genus and species, Methanonatronarchaeum thermophilum, with the type strain AMET1 T (DSM 26684 T =NBRC 110805 T =UNIQEM U982 T ), and the salt lake methanogens into a candidate genus and species 'Candidatus Methanohalarchaeum thermophilum'. These organisms are proposed to form novel family, order and class Methanonatronarchaeaceae fam. nov., Methanonatronarchaeales ord. nov. and Methanonatronarchaeia classis nov., within the phylum Euryarchaeota.

Development of Multiwell-Plate Methods Using Pure Cultures of Methanogens To Identify New Inhibitors for Suppressing Ruminant Methane Emissions.

PubMed

Weimar, M R; Cheung, J; Dey, D; McSweeney, C; Morrison, M; Kobayashi, Y; Whitman, W B; Carbone, V; Schofield, L R; Ronimus, R S; Cook, G M

2017-08-01

Hydrogenotrophic methanogens typically require strictly anaerobic culturing conditions in glass tubes with overpressures of H 2 and CO 2 that are both time-consuming and costly. To increase the throughput for screening chemical compound libraries, 96-well microtiter plate methods for the growth of a marine (environmental) methanogen Methanococcus maripaludis strain S2 and the rumen methanogen Methanobrevibacter species AbM4 were developed. A number of key parameters (inoculum size, reducing agents for medium preparation, assay duration, inhibitor solvents, and culture volume) were optimized to achieve robust and reproducible growth in a high-throughput microtiter plate format. The method was validated using published methanogen inhibitors and statistically assessed for sensitivity and reproducibility. The Sigma-Aldrich LOPAC library containing 1,280 pharmacologically active compounds and an in-house natural product library (120 compounds) were screened against M. maripaludis as a proof of utility. This screen identified a number of bioactive compounds, and MIC values were confirmed for some of them against M. maripaludis and M. AbM4. The developed method provides a significant increase in throughput for screening compound libraries and can now be used to screen larger compound libraries to discover novel methanogen-specific inhibitors for the mitigation of ruminant methane emissions. IMPORTANCE Methane emissions from ruminants are a significant contributor to global greenhouse gas emissions, and new technologies are required to control emissions in the agriculture technology (agritech) sector. The discovery of small-molecule inhibitors of methanogens using high-throughput phenotypic (growth) screening against compound libraries (synthetic and natural products) is an attractive avenue. However, phenotypic inhibitor screening is currently hindered by our inability to grow methanogens in a high-throughput format. We have developed, optimized, and validated a high

Aluminium tolerance and high phosphorus efficiency helps Stylosanthes better adapt to low-P acid soils.

PubMed

Du, Yu-Mei; Tian, Jiang; Liao, Hong; Bai, Chang-Jun; Yan, Xiao-Long; Liu, Guo-Dao

2009-06-01

Stylosanthes spp. (stylo) is one of the most important pasture legumes used in a wide range of agricultural systems on acid soils, where aluminium (Al) toxicity and phosphorus (P) deficiency are two major limiting factors for plant growth. However, physiological mechanisms of stylo adaptation to acid soils are not understood. Twelve stylo genotypes were surveyed under field conditions, followed by sand and nutrient solution culture experiments to investigate possible physiological mechanisms of stylo adaptation to low-P acid soils. Stylo genotypes varied substantially in growth and P uptake in low P conditions in the field. Three genotypes contrasting in P efficiency were selected for experiments in nutrient solution and sand culture to examine their Al tolerance and ability to utilize different P sources, including Ca-P, K-P, Al-P, Fe-P and phytate-P. Among the three tested genotypes, the P-efficient genotype 'TPRC2001-1' had higher Al tolerance than the P-inefficient genotype 'Fine-stem' as indicated by relative tap root length and haematoxylin staining. The three genotypes differed in their ability to utilize different P sources. The P-efficient genotype, 'TPRC2001-1', had superior ability to utilize phytate-P. The findings suggest that possible physiological mechanisms of stylo adaptation to low-P acid soils might involve superior ability of plant roots to tolerate Al toxicity and to utilize organic P and Al-P.

Improved Monitoring of Semi-Continuous Anaerobic Digestion of Sugarcane Waste: Effects of Increasing Organic Loading Rate on Methanogenic Community Dynamics

PubMed Central

Leite, Athaydes Francisco; Janke, Leandro; Lv, Zuopeng; Harms, Hauke; Richnow, Hans-Hermann; Nikolausz, Marcell

2015-01-01

The anaerobic digestion of filter cake and its co-digestion with bagasse, and the effect of gradual increase of the organic loading rate (OLR) from start-up to overload were investigated. Understanding the influence of environmental and technical parameters on the development of particular methanogenic pathway in the biogas process was an important aim for the prediction and prevention of process failure. The rapid accumulation of volatile organic acids at high OLR of 3.0 to 4.0 gvs·L−1·day−1 indicated strong process inhibition. Methanogenic community dynamics of the reactors was monitored by stable isotope composition of biogas and molecular biological analysis. A potential shift toward the aceticlastic methanogenesis was observed along with the OLR increase under stable reactor operating conditions. Reactor overloading and process failure were indicated by the tendency to return to a predominance of hydrogenotrophic methanogenesis with rising abundances of the orders Methanobacteriales and Methanomicrobiales and drop of the genus Methanosarcina abundance. PMID:26404240

Survey of Extreme Solvent Tolerance in Gram-Positive Cocci: Membrane Fatty Acid Changes in Staphylococcus haemolyticus Grown in Toluene

PubMed Central

Nielsen, Lindsey E.; Kadavy, Dana R.; Rajagopal, Soumitra; Drijber, Rhae; Nickerson, Kenneth W.

2005-01-01

We exploited the unique ecological niche of oil fly larval guts to isolate a strain of Staphylococcus haemolyticus which may be the most solvent-tolerant gram-positive bacterium yet described. This organism is able to tolerate 100% toluene, benzene, and p-xylene on plate overlays and saturating levels of these solvents in monophasic liquid cultures. A comparison of membrane fatty acids by gas chromatography after growth in liquid media with and without toluene showed that in cells continuously exposed to solvent the proportion of anteiso fatty acids increased from 25.8 to 33.7% while the proportion of 20:0 straight-chain fatty acids decreased from 19.3 to 10.1%. No changes in the membrane phospholipid composition were noted. Thus, S. haemolyticus alters its membrane fluidity via fatty acid composition to become more fluid when it is exposed to solvent. This response is opposite that commonly found in gram-negative bacteria, which change their fatty acids so that the cytoplasmic membrane is less fluid. Extreme solvent tolerance in S. haemolyticus is not accompanied by abnormal resistance to anionic or cationic detergents. Finally, six strains of Staphylococcus aureus and five strains of Staphylococcus epidermidis, which were not obtained by solvent selection, also exhibited exceptional solvent tolerance. PMID:16151101

Survey of extreme solvent tolerance in gram-positive cocci: membrane fatty acid changes in Staphylococcus haemolyticus grown in toluene.

PubMed

Nielsen, Lindsey E; Kadavy, Dana R; Rajagopal, Soumitra; Drijber, Rhae; Nickerson, Kenneth W

2005-09-01

We exploited the unique ecological niche of oil fly larval guts to isolate a strain of Staphylococcus haemolyticus which may be the most solvent-tolerant gram-positive bacterium yet described. This organism is able to tolerate 100% toluene, benzene, and p-xylene on plate overlays and saturating levels of these solvents in monophasic liquid cultures. A comparison of membrane fatty acids by gas chromatography after growth in liquid media with and without toluene showed that in cells continuously exposed to solvent the proportion of anteiso fatty acids increased from 25.8 to 33.7% while the proportion of 20:0 straight-chain fatty acids decreased from 19.3 to 10.1%. No changes in the membrane phospholipid composition were noted. Thus, S. haemolyticus alters its membrane fluidity via fatty acid composition to become more fluid when it is exposed to solvent. This response is opposite that commonly found in gram-negative bacteria, which change their fatty acids so that the cytoplasmic membrane is less fluid. Extreme solvent tolerance in S. haemolyticus is not accompanied by abnormal resistance to anionic or cationic detergents. Finally, six strains of Staphylococcus aureus and five strains of Staphylococcus epidermidis, which were not obtained by solvent selection, also exhibited exceptional solvent tolerance.

Impact of desiccation and heat exposure stress on Salmonella tolerance to acidic conditions.

PubMed

Richardson, Kurt E; Cox, Nelson A; Cosby, Douglas E; Berrang, Mark E

2018-02-01

In a recent study, the pH of commonly used Salmonella pre-enrichment media became acidic (pH 4.0 to 5.0) when feed or feed ingredients were incubated for 24 h. Acidic conditions have been reported to injure or kill Salmonella. In this study, cultures of four known feed isolates (S. montevideo, S. senftenberg, S. tennessee, and S. schwarzengrund) and four important processing plant isolates (S. typhimurium, S. enteritidis, S. infantis, and S. heidelberg) were grown on meat and bone meal and later subjected to desiccation and heat exposure to stress the microorganism. The impact of stress on the isolates ability to survive in acidic conditions ranging from pH 4.0 to 7.0 was compared to the non-stressed isolate. Cell injury was determined on xylose lysine tergitol 4 (XLT4) and cell death determined on nutrient agar (NA). When measured by cell death in non-stressed Salmonella, S. typhimurium was the most acid tolerant and S. heidelberg was the most acid sensitive whereas in stressed Salmonella, S. senftenberg was the most acid tolerant and S. tennessee was the most acid sensitive. The pH required to cause cell injury varied among isolates. With some isolates, the pH required for 50% cell death and 50% cell injury was similar. In other isolates, cell injury occurred at a more neutral pH. These findings suggest that the pH of pre-enrichment media may influence the recovery and bias the serotype of Salmonella recovered from feed during pre-enrichment.

The nif Gene Operon of the Methanogenic Archaeon Methanococcus maripaludis

PubMed Central

Kessler, Peter S.; Blank, Carrine; Leigh, John A.

1998-01-01

Nitrogen fixation occurs in two domains, Archaea and Bacteria. We have characterized a nif (nitrogen fixation) gene cluster in the methanogenic archaeon Methanococcus maripaludis. Sequence analysis revealed eight genes, six with sequence similarity to known nif genes and two with sequence similarity to glnB. The gene order, nifH, ORF105 (similar to glnB), ORF121 (similar to glnB), nifD, nifK, nifE, nifN, and nifX, was the same as that found in part in other diazotrophic methanogens and except for the presence of the glnB-like genes, also resembled the order found in many members of the Bacteria. Using transposon insertion mutagenesis, we determined that an 8-kb region required for nitrogen fixation corresponded to the nif gene cluster. Northern analysis revealed the presence of either a single 7.6-kb nif mRNA transcript or 10 smaller mRNA species containing portions of the large transcript. Polar effects of transposon insertions demonstrated that all of these mRNAs arose from a single promoter region, where transcription initiated 80 bp 5′ to nifH. Distinctive features of the nif gene cluster include the presence of the six primary nif genes in a single operon, the placement of the two glnB-like genes within the cluster, the apparent physical separation of the cluster from any other nif genes that might be in the genome, the fragmentation pattern of the mRNA, and the regulation of expression by a repression mechanism described previously. Our study and others with methanogenic archaea reporting multiple mRNAs arising from gene clusters with only a single putative promoter sequence suggest that mRNA processing following transcription may be a common occurrence in methanogens. PMID:9515920

Aciduricity and acid tolerance mechanisms of Streptococcus anginosus.

PubMed

Sasaki, Minoru; Kodama, Yoshitoyo; Shimoyama, Yu; Ishikawa, Taichi; Kimura, Shigenobu

2018-04-17

Although Streptococcus anginosus constitutes a proportion of the normal flora of the gastrointestinal and genital tracts, and the oral cavity, it has been reported that S. anginosus infection could be closely associated with abscesses at various body sites, infective endocarditis, and upper gastrointestinal cancers. The colonization in an acidic environment due to the aciduricity of S. anginosus could be the etiology of the systemic infection of the bacteria. To elucidate the aciduricity and acid tolerance mechanisms of the microbe, we examined the viability and growth of S. anginosus under acidic conditions. The viabilities of S. anginosus NCTC 10713 and Streptococcus mutans ATCC 25175 at pH 4.0 showed as being markedly higher than those of Streptococcus sanguinis ATCC 10556, Streptococcus gordonii ATCC 10558, and Streptococcus mitis ATCC 49456; however, the viability was partially inhibited by dicyclohexylcarbodiimide, an H + -ATPase inhibitor, suggesting that H + -ATPase could play a role in the viability of S. anginosus under acidic conditions. In addition, S. anginosus NCTC 10713 could grow at pH 5.0 and showed a marked arginine deiminase (ADI) activity, unlike its ΔarcA mutant, deficient in the gene encoding ADI, and other streptococcal species, which indicated that ADI could also be associated with aciduricity. These results suggest that S. anginosus has significant aciduric properties, which can be attributed to these enzyme activities.

Long-term effects of operating temperature and sulphate addition on the methanogenic community structure of anaerobic hybrid reactors.

PubMed

Pender, Seán; Toomey, Margaret; Carton, Micheál; Eardly, Dónal; Patching, John W; Colleran, Emer; O'Flaherty, Vincent

2004-02-01

The diversity, population dynamics, and activity profiles of methanogens in anaerobic granular sludges from two anaerobic hybrid reactors treating a molasses wastewater both mesophilically (37 degrees C) and thermophilically (55 degrees C) during a 1081 day trial were determined. The influent to one of the reactors was supplemented with sulphate, after an acclimation period of 112 days, to determine the effect of competition with sulphate-reducing bacteria on the methanogenic community structure. Sludge samples were removed from the reactors at intervals throughout the operational period and examined by amplified ribosomal DNA (rDNA) restriction analysis (ARDRA) and partial sequencing of 16S rRNA genes. In total, 18 operational taxonomic units (OTUs) were identified, 12 of which were sequenced. The methanogenic communities in both reactors changed during the operational period. The seed sludge and the reactor biomass sampled during mesophilic operation, both in the presence and absence of sulphate, was characterised by a predominance of Methanosaeta spp. Following temperature elevation, the dominant methanogenic sequences detected in the non-sulphate supplemented reactor were closely related to Methanocorpusculum parvum. By contrast, the dominant OTUs detected in the sulphate-supplemented reactor upon temperature increase were related to the hydrogen-utilising methanogen, Methanobacterium thermoautotrophicum. The observed methanogenic community structure in the reactors correlated with the operational performance of the reactors during the trial and with physiological measurements of the reactor biomass. Both reactors achieved chemical oxygen demand (COD) removal efficiencies of over 90% during mesophilic operation, with or without sulphate supplementation. During thermophilic operation, the presence of sulphate resulted in decreased reactor performance (effluent acetate concentrations of >3000 mg/l and biogas methane content of <25%). It was demonstrated that

Molecular analysis of methanogenic archaea in the forestomach of the alpaca (Vicugna pacos)

PubMed Central

2012-01-01

Background Methanogens that populate the gastrointestinal tract of livestock ruminants contribute significantly to methane emissions from the agriculture industry. There is a great need to analyze archaeal microbiomes from a broad range of host species in order to establish causal relationships between the structure of methanogen communities and their potential for methane emission. In this report, we present an investigation of methanogenic archaeal populations in the foregut of alpacas. Results We constructed individual 16S rRNA gene clone libraries from five sampled animals and recovered a total of 947 sequences which were assigned to 51 species-level OTUs. Individuals were found to each have between 21 and 27 OTUs, of which two to six OTUs were unique. As reported in other host species, Methanobrevibacter was the dominant genus in the alpaca, representing 88.3% of clones. However, the alpaca archaeal microbiome was different from other reported host species, as clones showing species-level identity to Methanobrevibacter millerae were the most abundant. Conclusion From our analysis, we propose a model to describe the population structure of Methanobrevibacter-related methanogens in the alpaca and in previously reported host species, which may contribute in unraveling the complexity of symbiotic archaeal communities in herbivores. PMID:22221383

A portable anaerobic microbioreactor reveals optimum growth conditions for the methanogen Methanosaeta concilii.

PubMed

Steinhaus, Benjamin; Garcia, Marcelo L; Shen, Amy Q; Angenent, Largus T

2007-03-01

Conventional studies of the optimum growth conditions for methanogens (methane-producing, obligate anaerobic archaea) are typically conducted with serum bottles or bioreactors. The use of microfluidics to culture methanogens allows direct microscopic observations of the time-integrated response of growth. Here, we developed a microbioreactor (microBR) with approximately 1-microl microchannels to study some optimum growth conditions for the methanogen Methanosaeta concilii. The microBR is contained in an anaerobic chamber specifically designed to place it directly onto an inverted light microscope stage while maintaining a N2-CO2 environment. The methanogen was cultured for months inside microchannels of different widths. Channel width was manipulated to create various fluid velocities, allowing the direct study of the behavior and responses of M. concilii to various shear stresses and revealing an optimum shear level of approximately 20 to 35 microPa. Gradients in a single microchannel were then used to find an optimum pH level of 7.6 and an optimum total NH4-N concentration of less than 1,100 mg/liter (<47 mg/liter as free NH3-N) for M. concilii under conditions of the previously determined ideal shear stress and pH and at a temperature of 35 degrees C.

Tolerance and safety of superficial chemical peeling with salicylic acid in various facial dermatoses.

PubMed

Bari, Arfan Ul; Iqbal, Zafar; Rahman, Simeen Ber

2005-01-01

Chemical peeling is a skin-wounding procedure that may have some potentially undesirable side-effects. The present study is directed towards safety concerns associated with superficial chemical peeling with salicylic acid in various facial dermatoses. The study was a non-comparative and a prospective one. Two hundred and sixty-eight patients of either sex, aged between 10 to 60 years, undergoing superficial chemical peeling for various facial dermatoses (melasma, acne vulgaris, freckles, post-inflammatory scars/pigmentation, actinic keratoses, plane facial warts, etc.) were included in the study. Eight weekly peeling sessions were carried out in each patient. Tolerance to the procedure and any undesirable effects noted during these sessions were recorded. Almost all the patients tolerated the procedure well. Mild discomfort, burning, irritation and erythema were quite common but the incidence of major side-effects was very low and these too, were easily manageable. There was no significant difference in the incidence of side-effects between facial dermatoses (melasma, acne and other pigmentary disorders). Chemical peeling with salicylic acid is a well tolerated and safe treatment modality in many superficial facial dermatoses.

Comparative proteomic analysis of differentially expressed proteins in β-aminobutyric acid enhanced Arabidopsis thaliana tolerance to simulated acid rain.

PubMed

Liu, Tingwu; Jiang, Xinwu; Shi, Wuliang; Chen, Juan; Pei, Zhenming; Zheng, Hailei

2011-05-01

Acid rain is a worldwide environmental issue that has seriously destroyed forest ecosystems. As a highly effective and broad-spectrum plant resistance-inducing agent, β-aminobutyric acid could elevate the tolerance of Arabidopsis when subjected to simulated acid rain. Using comparative proteomic strategies, we analyzed 203 significantly varied proteins of which 175 proteins were identified responding to β-aminobutyric acid in the absence and presence of simulated acid rain. They could be divided into ten groups according to their biological functions. Among them, the majority was cell rescue, development and defense-related proteins, followed by transcription, protein synthesis, folding, modification and destination-associated proteins. Our conclusion is β-aminobutyric acid can lead to a large-scale primary metabolism change and simultaneously activate antioxidant system and salicylic acid, jasmonic acid, abscisic acid signaling pathways. In addition, β-aminobutyric acid can reinforce physical barriers to defend simulated acid rain stress. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

The Effects of Perchlorate on Methane Production of Methanogens

NASA Astrophysics Data System (ADS)

Goodhart, T.; Kral, T. A.

2010-04-01

In May 2008, the Phoenix space craft analyzed the martian soil, detecting perchlorate, which is a highly oxidizing compound and potentially harmful to organic matter. This presentation discusses the effects that perchlorate has on methanogen growth.

Choline and N,N-dimethylethanolamine as direct substrates for methanogens.

PubMed

Watkins, Andrew J; Roussel, Erwan G; Webster, Gordon; Parkes, R John; Sass, Henrik

2012-12-01

Choline (N,N,N-trimethylethanolamine), which is widely distributed in membrane lipids and is a component of sediment biota, has been shown to be utilized anaerobically by mixed prokaryote cultures to produce methane but not by pure cultures of methanogens. Here, we show that five recently isolated Methanococcoides strains from a range of sediments (Aarhus Bay, Denmark; Severn Estuary mudflats at Portishead, United Kingdom; Darwin Mud Volcano, Gulf of Cadiz; Napoli mud volcano, eastern Mediterranean) can directly utilize choline for methanogenesis producing ethanolamine, which is not further metabolized. Di- and monomethylethanolamine are metabolic intermediates that temporarily accumulate. Consistent with this, dimethylethanolamine was shown to be another new growth substrate, but monomethylethanolamine was not. The specific methanogen inhibitor 2-bromoethanesulfonate (BES) inhibited methane production from choline. When choline and trimethylamine are provided together, diauxic growth occurs, with trimethylamine being utilized first, and then after a lag (∼7 days) choline is metabolized. Three type strains of Methanococcoides (M. methylutens, M. burtonii, and M. alaskense), in contrast, did not utilize choline. However, two of them (M. methylutens and M. burtonii) did metabolize dimethylethanolamine. These results extend the known substrates that can be directly utilized by some methanogens, giving them the advantage that they would not be reliant on bacterial syntrophs for their substrate supply.

Choline and N,N-Dimethylethanolamine as Direct Substrates for Methanogens

PubMed Central

Watkins, Andrew J.; Roussel, Erwan G.; Webster, Gordon; Parkes, R. John

2012-01-01

Choline (N,N,N-trimethylethanolamine), which is widely distributed in membrane lipids and is a component of sediment biota, has been shown to be utilized anaerobically by mixed prokaryote cultures to produce methane but not by pure cultures of methanogens. Here, we show that five recently isolated Methanococcoides strains from a range of sediments (Aarhus Bay, Denmark; Severn Estuary mudflats at Portishead, United Kingdom; Darwin Mud Volcano, Gulf of Cadiz; Napoli mud volcano, eastern Mediterranean) can directly utilize choline for methanogenesis producing ethanolamine, which is not further metabolized. Di- and monomethylethanolamine are metabolic intermediates that temporarily accumulate. Consistent with this, dimethylethanolamine was shown to be another new growth substrate, but monomethylethanolamine was not. The specific methanogen inhibitor 2-bromoethanesulfonate (BES) inhibited methane production from choline. When choline and trimethylamine are provided together, diauxic growth occurs, with trimethylamine being utilized first, and then after a lag (∼7 days) choline is metabolized. Three type strains of Methanococcoides (M. methylutens, M. burtonii, and M. alaskense), in contrast, did not utilize choline. However, two of them (M. methylutens and M. burtonii) did metabolize dimethylethanolamine. These results extend the known substrates that can be directly utilized by some methanogens, giving them the advantage that they would not be reliant on bacterial syntrophs for their substrate supply. PMID:23001649

Windrow composting mitigated CH4 emissions: characterization of methanogenic and methanotrophic communities in manure management.

PubMed

Chen, Ruirui; Wang, Yiming; Wei, Shiping; Wang, Wei; Lin, Xiangui

2014-12-01

With increasing livestock breeding, methane (CH4 ) emissions from manure management will increasingly contribute more to atmospheric CH4 concentration. The dynamics of methanogens and methanotrophs have not yet been studied in the manure environment. The current study combines surface CH4 emissions with methanogenic and methanotrophic community analyses from two management practices, windrow composting (WCOM) and solid storage (SSTO). Our results showed that there was an c. 50% reduction of CH4 emissions with WCOM compared with SSTO over a 50-day period. A sharp decrease in the quantities of both methanogens and methanotrophs in WCOM suggested that CH4 mitigation was mainly due to decreased CH4 production rather than increased CH4 oxidation. Pyrosequencing analysis demonstrated that aeration caused a clear shift of dominant methanogens in the manure, with specifically a significant decrease in Methanosarcina and increase in Methanobrevibacter. The composition of methanogenic community was influenced by manure management and regulated CH4 production. A sharp increase in the quantity of methanotrophs in SSTO suggested that microbial CH4 oxidation is an important sink for the CH4 produced. The increased abundance of Methylococcaceae in SSTO suggested that Type I methanotrophs have an advantage in CH4 oxidation in occupying niches under low CH4 and high O2 conditions. © 2014 Federation of European Microbiological Societies. Published by John Wiley & Sons Ltd. All rights reserved.

Methanogenic activity and diversity in the centre of the Amsterdam Mud Volcano, Eastern Mediterranean Sea.

PubMed

Lazar, Cassandre Sara; John Parkes, R; Cragg, Barry A; L'Haridon, Stephane; Toffin, Laurent

2012-07-01

Marine mud volcanoes are geological structures emitting large amounts of methane from their active centres. The Amsterdam mud volcano (AMV), located in the Anaximander Mountains south of Turkey, is characterized by intense active methane seepage produced in part by methanogens. To date, information about the diversity or the metabolic pathways used by the methanogens in active centres of marine mud volcanoes is limited. (14)C-radiotracer measurements showed that methylamines/methanol, H(2)/CO(2) and acetate were used for methanogenesis in the AMV. Methylotrophic methanogenesis was measured all along the sediment core, Methanosarcinales affiliated sequences were detected using archaeal 16S PCR-DGGE and mcrA gene libraries, and enrichments of methanogens showed the presence of Methanococcoides in the shallow sediment layers. Overall acetoclastic methanogenesis was higher than hydrogenotrophic methanogenesis, which is unusual for cold seep sediments. Interestingly, acetate porewater concentrations were extremely high in the AMV sediments. This might be the result of organic matter cracking in deeper hotter sediment layers. Methane was also produced from hexadecanes. For the most part, the methanogenic community diversity was in accordance with the depth distribution of the H(2)/CO(2) and acetate methanogenesis. These results demonstrate the importance of methanogenic communities in the centres of marine mud volcanoes. © 2012 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.

77 FR 53144 - Nitric Acid; Exemption From the Requirement of a Tolerance

Federal Register 2010, 2011, 2012, 2013, 2014

2012-08-31

... Cosmetic Act (FFDCA), requesting establishment of an exemption from the requirement of a tolerance. This... ingredients. IV. Aggregate Risk Assessment and Determination of Safety Section 408(c)(2)(A)(i) of FFDCA allows... to assess the hazards of and to make a determination on aggregate exposure for nitric acid including...

The Genome Sequence of the Rumen Methanogen Methanobrevibacter ruminantium Reveals New Possibilities for Controlling Ruminant Methane Emissions

PubMed Central

Leahy, Sinead C.; Kelly, William J.; Altermann, Eric; Ronimus, Ron S.; Yeoman, Carl J.; Pacheco, Diana M.; Li, Dong; Kong, Zhanhao; McTavish, Sharla; Sang, Carrie; Lambie, Suzanne C.; Janssen, Peter H.; Dey, Debjit; Attwood, Graeme T.

2010-01-01

Background Methane (CH4) is a potent greenhouse gas (GHG), having a global warming potential 21 times that of carbon dioxide (CO2). Methane emissions from agriculture represent around 40% of the emissions produced by human-related activities, the single largest source being enteric fermentation, mainly in ruminant livestock. Technologies to reduce these emissions are lacking. Ruminant methane is formed by the action of methanogenic archaea typified by Methanobrevibacter ruminantium, which is present in ruminants fed a wide variety of diets worldwide. To gain more insight into the lifestyle of a rumen methanogen, and to identify genes and proteins that can be targeted to reduce methane production, we have sequenced the 2.93 Mb genome of M. ruminantium M1, the first rumen methanogen genome to be completed. Methodology/Principal Findings The M1 genome was sequenced, annotated and subjected to comparative genomic and metabolic pathway analyses. Conserved and methanogen-specific gene sets suitable as targets for vaccine development or chemogenomic-based inhibition of rumen methanogens were identified. The feasibility of using a synthetic peptide-directed vaccinology approach to target epitopes of methanogen surface proteins was demonstrated. A prophage genome was described and its lytic enzyme, endoisopeptidase PeiR, was shown to lyse M1 cells in pure culture. A predicted stimulation of M1 growth by alcohols was demonstrated and microarray analyses indicated up-regulation of methanogenesis genes during co-culture with a hydrogen (H2) producing rumen bacterium. We also report the discovery of non-ribosomal peptide synthetases in M. ruminantium M1, the first reported in archaeal species. Conclusions/Significance The M1 genome sequence provides new insights into the lifestyle and cellular processes of this important rumen methanogen. It also defines vaccine and chemogenomic targets for broad inhibition of rumen methanogens and represents a significant contribution to

40 CFR 180.1196 - Peroxyacetic acid; exemption from the requirement of a tolerance.

Code of Federal Regulations, 2011 CFR

2011-07-01

... AGENCY (CONTINUED) PESTICIDE PROGRAMS TOLERANCES AND EXEMPTIONS FOR PESTICIDE CHEMICAL RESIDUES IN FOOD... antimicrobial treatment in solutions containing a diluted end use concentration of peroxyacetic acid up to 100... food commodities when used in sanitizing solutions containing a diluted end-use concentration of...

Methanolobus taylorii sp nov, a new methylotropic, estuarine methanogen

USGS Publications Warehouse

Oremland, Ronald S.; Boone, David R.

1994-01-01

Strain GS-16T (T = type strain) is a methylotrophic methanogen that was isolated from estuarine sediments from San Francisco Bay (4) and has been deposited in the Oregon Collection of Methanogens (Oregon Graduate Institute, Portland) as strain OCM 5ST. This strain was isolated by using dimethyl sulfide as the catabolic substrate (4), but it can also grow on methylamines (13) and methanethiol (8, 9) and grew when it was inoculated into MSHA medium (6) supplemented with 20 mM methanol as the sole catabolic substrate. Strain GS-16T cells form methane from methylmercury (12) and dimethylselenide (16), although they cannot grow on these substrates, and form traces of ethane from diethyl sulfide (15). Methanogenesis from trimethylamine is inhibited by methyl fluoride (11) and methyl bromide (14), but not by dimethyl ether (1 1).

Production of itaconic acid from acetate by engineering acid-tolerant Escherichia coli W.

PubMed

Noh, Myung Hyun; Lim, Hyun Gyu; Woo, Sung Hwa; Song, Jinyi; Jung, Gyoo Yeol

2018-03-01

Utilization of abundant and cheap carbon sources can effectively reduce the production cost and enhance the economic feasibility. Acetate is a promising carbon source to achieve cost-effective microbial processes. In this study, we engineered an Escherichia coli strain to produce itaconic acid from acetate. As acetate is known to inhibit cell growth, we initially screened for a strain with a high tolerance to 10 g/L of acetate in the medium, and the W strain was selected as the host. Subsequently, the WC strain was obtained by overexpression of cad (encoding cis-aconitate decarboxylase) using a synthetic promoter and 5' UTR. However, the WC strain produced only 0.13 g/L itaconic acid because of low acetate uptake. To improve the production, the acetate assimilating pathway and glyoxylate shunt pathway were amplified by overexpression of pathway genes as well as its deregulation. The resulting strain, WCIAG4 produced 3.57 g/L itaconic acid (16.1% of theoretical maximum yield) after 88 hr of fermentation with rapid acetate assimilation. These efforts support that acetate can be a potential feedstock for biochemical production with engineered E. coli. © 2017 Wiley Periodicals, Inc.

Single-center, open-label study of a proprietary topical 0.5% salicylic acid-based treatment regimen containing sandalwood oil in adolescents and adults with mild to moderate acne.

PubMed

Moy, Ronald L; Levenson, Corey; So, Jeffrey J; Rock, James A

2012-12-01

A proprietary topical blend of salicylic acid and highly purified sandalwood oil from Australia was used in this open-label study in adolescents and adults with mild to moderate facial acne. The investigational regimen consisted of a foaming cleanser, an acne serum, a spot treatment, and a mask. Patients applied the treatment regimen as directed for 8 weeks. The primary efficacy measure was the percentage of patients assessed as improved, much improved, or very much improved according to the Global Aesthetic Improvement Scale (GAIS) ratings at week 8. Severity was rated using the Evaluator's Global Severity Scores (EGSS) at baseline and weeks 2, 4, and 8. Tolerability was assessed at baseline and weeks 2, 4, and 8 by asking patients to rate the severity of itching, scaling, erythema, burning, dryness, and stinging. Patients were also asked to complete an acne questionnaire. 89.4% (42/47) met the primary end point determined by the GAIS of improved (66%), much improved (19%), or very much improved (4%). Notable reductions in lesion counts were observed in patients with more severe or inflamed lesions. Tolerability was queried at all visits. No itching, scaling, or erythema was reported after initial application. Symptoms of intolerability peaked at week 2; however, most events were mild to moderate and were typically reported with use of the mask component. Intolerance decreased by week 4 and by week 8. The treatment regimen was well tolerated by patients. Results from this study support the use of a proprietary investigational regimen in patients with mild to moderate acne and warrant further investigation to determine whether longer-term therapy (ie, beyond 8 weeks) results in enhanced efficacy with minimal side effects, leading to continued patient compliance and skin improvement.

[Impact of liquid volume of recycled methanogenic effluent on anaerobic hydrolysis].

PubMed

Hao, Li-ping; Lü, Fan; He, Pin-jing; Shao, Li-ming

2008-09-01

Methanogenic effluent was recycled to regulate hydrolysis during two-phase anaerobic digestion of organic solid wastes. In order to study the impact of recycled effluent's volume on hydrolysis, four hydrolysis reactors filled with vegetable and flower wastes were constructed, with different liquid volumes of recycled methanogenic effluent, i.e., 0.1, 0.5, 1.0, 2.0 m3/(m3 x d), respectively. The parameters related to hydrolytic environment (pH, alkalinity, ORP, concentrations of ammonia and reducing sugar), microbial biomass and hydrolysis efficiency (accumulated SCOD, accumulated reducing sugar, and hydrolysis rate constants) were monitored. This research shows that recycling methanogenic effluent into the hydrolysis reactor can enhance its buffer capability and operation stability; higher recycled volume is favorable for microbial anabolism and further promotes hydrolysis. After 9 days of reaction, the accumulated SCOD in the hydrolytic effluent reach 334, 407, 413, 581 mg/g at recycled volumes of 0.1, 0.5, 1.0, 2.0 m3/(m3 x d) and their first-order hydrolysis rate kinetic constants are 0.065, 0.083, 0.089, 0.105 d(-1), respectively.

Methanogenic community shifts during the transition from sewage mono-digestion to co-digestion of grass biomass.

PubMed

Hardegen, Justus; Latorre-Pérez, Adriel; Vilanova, Cristina; Günther, Thomas; Porcar, Manuel; Luschnig, Olaf; Simeonov, Claudia; Abendroth, Christian

2018-06-06

In this work, liquid and solid fractions of grass biomass were used as co-substrates for anaerobic co-digestion of sewage sludge. The input of grass biomass was increased gradually, and the underlying methanogenic microbiome was assessed by means of microscopy-based cell counting and full-length 16S rRNA gene high-throughput sequencing, proving for the first time the suitability of nanopore-based portable sequencers as a monitoring tool for anaerobic digestion systems. In both cases co-fermentation resulted in an increased number of bacteria and methanogenic archaea. Interestingly, the microbial communities were highly different between solid and liquid-fed batches. Liquid-fed batches developed a more stable microbiome, enriched in Methanosarcina spp., and resulted in higher methanogenic yield. In contrast, solid-fed batches were highly unstable at higher substrate concentrations, and kept Methanosaeta spp. - typically associated to sewage sludge - as the majoritary methanogenic archaea. Copyright © 2018 Elsevier Ltd. All rights reserved.

Heat tolerance of automotive lead-acid batteries

NASA Astrophysics Data System (ADS)

Albers, Joern

Starter batteries have to withstand a quite large temperature range. In Europe, the battery temperature can be -30 °C in winter and may even exceed +60 °C in summer. In most modern cars, there is not much space left in the engine compartment to install the battery. So the mean battery temperature may be higher than it was some decades ago. In some car models, the battery is located in the passenger or luggage compartment, where ambient temperatures are more moderate. Temperature effects are discussed in detail. The consequences of high heat impact into the lead-acid battery may vary for different battery technologies: While grid corrosion is often a dominant factor for flooded lead-acid batteries, water loss may be an additional influence factor for valve-regulated lead-acid batteries. A model was set up that considers external and internal parameters to estimate the water loss of AGM batteries. Even under hot climate conditions, AGM batteries were found to be highly durable and superior to flooded batteries in many cases. Considering the real battery temperature for adjustment of charging voltage, negative effects can be reduced. Especially in micro-hybrid applications, AGM batteries cope with additional requirements much better than flooded batteries, and show less sensitivity to high temperatures than suspected sometimes.

Activation of CO2-reducing methanogens in oil reservoir after addition of nutrient.

PubMed

Yang, Guang-Chao; Zhou, Lei; Mbadinga, Serge Maurice; You, Jing; Yang, Hua-Zhen; Liu, Jin-Feng; Yang, Shi-Zhong; Gu, Ji-Dong; Mu, Bo-Zhong

2016-12-01

Nutrient addition as part of microbial enhanced oil recovery (MEOR) operations have important implications for more energy recovery from oil reservoirs, but very little is known about the in situ response of microorganisms after intervention. An analysis of two genes as biomarkers, mcrA encoding the key enzyme in methanogenesis and fthfs encoding the key enzyme in acetogenesis, was conducted during nutrient addition in oil reservoir. Clone library data showed that dominant mcrA sequences changed from acetoclastic (Methanosaetaceae) to CO 2 -reducing methanogens (Methanomicrobiales and Methanobacteriales), and the authentic acetogens affiliated to Firmicutes decreased after the intervention. Principal coordinates analysis (PCoA) and Jackknife environment clusters revealed evidence on the shift of the microbial community structure among the samples. Quantitative analysis of methanogens via qPCR showed that Methanobacteriales and Methanomicrobiales increased after nutrient addition, while acetoclastic methanogens (Methanosaetaceae) changed slightly. Nutrient treatment activated native CO 2 -reducing methanogens in oil reservoir. The high frequency of Methanobacteriales and Methanomicrobiales (CO 2 -reducers) after nutrient addition in this petroleum system suggested that CO 2 -reducing methanogenesis was involved in methane production. The nutrient addition could promote the methane production. The results will likely improve strategies of utilizing microorganisms in subsurface environments. Copyright © 2016 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

Safety and tolerability of low-dose naltrexone therapy in children with moderate to severe Crohn's disease: a pilot study.

PubMed

Smith, Jill P; Field, Douglas; Bingaman, Sandra I; Evans, Robert; Mauger, David T

2013-04-01

There is an unmet need for safe and effective medicines to treat children with Crohn's disease. Recently, investigations have shown an association between endogenous opioid peptides and inflammatory cells. The aims of this study were to evaluate the safety and tolerability of an opioid antagonist, naltrexone, in children with moderate to severe Crohn's disease. A pilot clinical trial was conducted in children with moderate to severe Crohn's disease. Fourteen subjects with a mean age of 12.3 years (range, 8 to 17 y) were enrolled. Children were randomized to placebo or naltrexone (0.1 mg/kg) orally for 8 weeks followed by open-labeled treatment with 8 additional weeks of naltrexone. Safety and toxicity were monitored by physical examinations and blood chemistries. Clinical activity was assessed by the Pediatric Crohn's Disease Activity Index (PCDAI) and Quality of life was monitored by the Impact III survey. Oral naltrexone was well tolerated without any serious adverse events in children with moderate to severe Crohn's disease. PCDAI scores significantly decreased from pretreatment values (34.2±3.3) with an 8-week course of naltrexone therapy (21.7±3.9) (P=0.005). Twenty-five percent of those treated with naltrexone were considered in remission (score ≤10) and 67% had improved with mild disease activity (decrease in PCDAI score by at least 10 points) at the end of the study. Systemic and social quality of life improved with naltrexone treatment (P=0.035). Naltrexone therapy seems safe with limited toxicity when given to children with Crohn's disease and may reduce disease activity.

Differences in acid tolerance between Bifidobacterium breve BB8 and its acid-resistant derivative B. breve BB8dpH, revealed by RNA-sequencing and physiological analysis.

PubMed

Yang, Xu; Hang, Xiaomin; Tan, Jing; Yang, Hong

2015-06-01

Bifidobacteria are common inhabitants of the human gastrointestinal tract, and their application has increased dramatically in recent years due to their health-promoting effects. The ability of bifidobacteria to tolerate acidic environments is particularly important for their function as probiotics because they encounter such environments in food products and during passage through the gastrointestinal tract. In this study, we generated a derivative, Bifidobacterium breve BB8dpH, which displayed a stable, acid-resistant phenotype. To investigate the possible reasons for the higher acid tolerance of B. breve BB8dpH, as compared with its parental strain B. breve BB8, a combined transcriptome and physiological approach was used to characterize differences between the two strains. An analysis of the transcriptome by RNA-sequencing indicated that the expression of 121 genes was increased by more than 2-fold, while the expression of 146 genes was reduced more than 2-fold, in B. breve BB8dpH. Validation of the RNA-sequencing data using real-time quantitative PCR analysis demonstrated that the RNA-sequencing results were highly reliable. The comparison analysis, based on differentially expressed genes, suggested that the acid tolerance of B. breve BB8dpH was enhanced by regulating the expression of genes involved in carbohydrate transport and metabolism, energy production, synthesis of cell envelope components (peptidoglycan and exopolysaccharide), synthesis and transport of glutamate and glutamine, and histidine synthesis. Furthermore, an analysis of physiological data showed that B. breve BB8dpH displayed higher production of exopolysaccharide and lower H(+)-ATPase activity than B. breve BB8. The results presented here will improve our understanding of acid tolerance in bifidobacteria, and they will lead to the development of new strategies to enhance the acid tolerance of bifidobacterial strains. Copyright © 2015 Elsevier Ltd. All rights reserved.

Hydrogen sulfide acts as a downstream signal molecule in salicylic acid-induced heat tolerance in maize (Zea mays L.) seedlings.

PubMed

Li, Zhong-Guang; Xie, Lin-Run; Li, Xiao-Juan

2015-04-01

Salicylic acid (SA), 2-hydroxy benzoic acid, is a small phenolic compound with multifunction that is involved in plant growth, development, and the acquisition of stress tolerance. In recent years, hydrogen sulfide (H2S) has been found to have similar functions, but cross talk between SA and H2S in the acquisition of heat tolerance is not clear. In this study, pretreatment of maize seedlings with SA improved the survival percentage of seedlings under heat stress, indicating that SA pretreatment could improve the heat tolerance of maize seedlings. In addition, treatment with SA enhanced the activity of L-cysteine desulfhydrase (L-DES), a key enzyme in H2S biosynthesis, which in turn induced accumulation of endogenous H2S. Interestingly, SA-induced heat tolerance was enhanced by addition of NaHS, a H2S donor, but weakened by specific inhibitors of H2S biosynthesis DL-propargylglycine (PAG) and its scavenger hydroxylamine (HT). Furthermore, pretreatment with paclobutrazol (PAC) and 2-aminoindan-2-phosphonic acid (AIP), inhibitors of SA biosynthesis, had no significant effect on NaHS-induced heat tolerance of maize seedlings. Similarly, significant change in the activities of phenylalanine ammonia lyase (PAL) and benzoic-acid-2-hydroxylase (BA2H), the key enzymes in SA biosynthesis, and the content of endogenous SA, was not observed in maize seedlings by NaHS treatment. All of the above-mentioned results suggest that SA pretreatment could improve the heat tolerance of maize seedlings, and H2S might be a novel downstream signal molecule in SA-induced heat tolerance. Copyright © 2015 Elsevier GmbH. All rights reserved.

Toxicity assessment of inorganic nanoparticles to acetoclastic and hydrogenotrophic methanogenic activity in anaerobic granular sludge.

PubMed

Gonzalez-Estrella, Jorge; Sierra-Alvarez, Reyes; Field, James A

2013-09-15

Release of engineered nanoparticles (NPs) to municipal wastewater from industrial and residential sources could impact biological systems in wastewater treatment plants. Methanogenic inhibition can cause failure of anaerobic waste(water) treatment. This study investigated the inhibitory effect of a wide array of inorganic NPs (Ag(0), Al₂O₃, CeO₂, Cu(0), CuO, Fe(0), Fe₂O₃, Mn₂O₃, SiO₂, TiO₂, and ZnO supplied up to 1500 mgL(-1)) to acetoclastic and hydrogenotrophic methanogenic activity of anaerobic granular sludge. Of all the NPs tested, only Cu(0) and ZnO caused severe methanogenic inhibition. The 50% inhibiting concentrations determined towards acetoclastic and hydrogenotrophic methanogens were 62 and 68 mgL(-1) for Cu(0) NP; and 87 and 250 mgL(-1) for ZnO NP, respectively. CuO NPs also caused inhibition of acetoclastic methanogens. Cu(2+) and Zn(2+) salts caused similar levels of inhibition as Cu(0) and ZnO NPs based on equilibrium soluble metal concentrations measured during the assays, suggesting that the toxicity was due to the release of metal ions by NP-corrosion. A commercial dispersant, Dispex, intended to increase NP stability did not affect the inhibitory impact of the NPs. The results taken as a whole suggest that Zn- and Cu-containing NPs can release metal ions that are inhibitory for methanogenesis. Copyright © 2013 Elsevier B.V. All rights reserved.

Enhance nisin yield via improving acid-tolerant capability of Lactococcus lactis F44.

PubMed

Zhang, Jian; Caiyin, Qinggele; Feng, Wenjing; Zhao, Xiuli; Qiao, Bin; Zhao, Guangrong; Qiao, Jianjun

2016-06-16

Traditionally, nisin was produced industrially by using Lactococcus lactis in the neutral fermentation process. However, nisin showed higher activity in the acidic environment. How to balance the pH value for bacterial normal growth and nisin activity might be the key problem. In this study, 17 acid-tolerant genes and 6 lactic acid synthetic genes were introduced in L. lactis F44, respectively. Comparing to the 2810 IU/mL nisin yield of the original strain F44, the nisin titer of the engineered strains over-expressing hdeAB, ldh and murG, increased to 3850, 3979 and 4377 IU/mL, respectively. These engineered strains showed more stable intracellular pH value during the fermentation process. Improvement of lactate production could partly provide the extra energy for the expression of acid tolerance genes during growth. Co-overexpression of hdeAB, murG, and ldh(Z) in strain F44 resulted in the nisin titer of 4913 IU/mL. The engineered strain (ABGL) could grow on plates with pH 4.2, comparing to the surviving pH 4.6 of strain F44. The fed-batch fermentation showed nisin titer of the co-expression L. lactis strain could reach 5563 IU/mL with lower pH condition and longer cultivation time. This work provides a novel strategy of constructing robust strains for use in industry process.

Bile salt tolerance of Lactococcus lactis is enhanced by expression of bile salt hydrolase thereby producing less bile acid in the cells.

PubMed

Bi, Jie; Liu, Song; Du, Guocheng; Chen, Jian

2016-04-01

Changes of bile salt tolerance, morphology and amount of bile acid within cells were studied to evaluate the exact effects of bile salt hydrolase (BSH) on bile salt tolerance of microorganism. The effect of BSHs on the bile salt tolerance of Lactococcus lactis was examined by expressing two BSHs (BSH1 and BSH2). Growth of L. lactis expressing BSH1 or BSH2 was better under bile salt stress compared to wild-type L. lactis. As indicated by transmission electron microscopy, bile acids released by the action of BSH induced the formation of micelles around the membrane surface of cells subject to conjugated bile salt stress. A similar micelle containing bile acid was observed in the cytoplasm by liquid chromatography-mass spectrometry. BSH1 produced fewer bile acid micelles in the cytoplasm and achieved better cell growth of L. lactis compared to BSH2. Expression of BSH improved bile salt tolerance of L. lactis but excessive production by BSH of bile acid micelles in the cytoplasm inhibited cell growth.

Molecular Biology and Physiology of Methanogenic Archaebacteria

DTIC Science & Technology

1989-06-27

anaerobic food chains, the methanogens contribute to the mineralization of large amounts of organic matter. The end product of their metabolism...of radiolabelled substrate to product [8; Worrell and Nagle, in preparation]. Strain RT103, a formate auxotroph was isolated from the kanamycin...methylmercaptopurine riboside 0. 16 Bacteriocidald 8-aza-2, 6-diaminopurine 0.0011 6-thioguanine 0.0004 8-azaguanine 0.0004 6- mercaptopurine 0 8

40 CFR 180.1023 - Propanoic acid; exemptions from the requirement of a tolerance.

Code of Federal Regulations, 2010 CFR

2010-07-01

...) Propanoic acid is exempt from the requirement of a tolerance for residues in or on cattle, meat; cattle, meat byproducts; goat, meat; goat, meat byproducts; hog, meat; hog meat byproducts; horse, meat; horse, meat byproducts; sheep, meat; sheep meat byproducts; and, poultry, fat; poultry meat; poultry meat...

Large-scale proteome analysis of abscisic acid and ABSCISIC ACID INSENSITIVE3-dependent proteins related to desiccation tolerance in Physcomitrella patens

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yotsui, Izumi, E-mail: izumi.yotsui@riken.jp; Serada, Satoshi, E-mail: serada@nibiohn.go.jp; Naka, Tetsuji, E-mail: tnaka@nibiohn.go.jp

2016-03-18

Desiccation tolerance is an ancestral feature of land plants and is still retained in non-vascular plants such as bryophytes and some vascular plants. However, except for seeds and spores, this trait is absent in vegetative tissues of vascular plants. Although many studies have focused on understanding the molecular basis underlying desiccation tolerance using transcriptome and proteome approaches, the critical molecular differences between desiccation tolerant plants and non-desiccation plants are still not clear. The moss Physcomitrella patens cannot survive rapid desiccation under laboratory conditions, but if cells of the protonemata are treated by the phytohormone abscisic acid (ABA) prior to desiccation,more » it can survive 24 h exposure to desiccation and regrow after rehydration. The desiccation tolerance induced by ABA (AiDT) is specific to this hormone, but also depends on a plant transcription factor ABSCISIC ACID INSENSITIVE3 (ABI3). Here we report the comparative proteomic analysis of AiDT between wild type and ABI3 deleted mutant (Δabi3) of P. patens using iTRAQ (Isobaric Tags for Relative and Absolute Quantification). From a total of 1980 unique proteins that we identified, only 16 proteins are significantly altered in Δabi3 compared to wild type after desiccation following ABA treatment. Among this group, three of the four proteins that were severely affected in Δabi3 tissue were Arabidopsis orthologous genes, which were expressed in maturing seeds under the regulation of ABI3. These included a Group 1 late embryogenesis abundant (LEA) protein, a short-chain dehydrogenase, and a desiccation-related protein. Our results suggest that at least three of these proteins expressed in desiccation tolerant cells of both Arabidopsis and the moss are very likely to play important roles in acquisition of desiccation tolerance in land plants. Furthermore, our results suggest that the regulatory machinery of ABA- and ABI3-mediated gene expression for

Large-scale proteome analysis of abscisic acid and ABSCISIC ACID INSENSITIVE3-dependent proteins related to desiccation tolerance in Physcomitrella patens.

PubMed

Yotsui, Izumi; Serada, Satoshi; Naka, Tetsuji; Saruhashi, Masashi; Taji, Teruaki; Hayashi, Takahisa; Quatrano, Ralph S; Sakata, Yoichi

2016-03-18

Desiccation tolerance is an ancestral feature of land plants and is still retained in non-vascular plants such as bryophytes and some vascular plants. However, except for seeds and spores, this trait is absent in vegetative tissues of vascular plants. Although many studies have focused on understanding the molecular basis underlying desiccation tolerance using transcriptome and proteome approaches, the critical molecular differences between desiccation tolerant plants and non-desiccation plants are still not clear. The moss Physcomitrella patens cannot survive rapid desiccation under laboratory conditions, but if cells of the protonemata are treated by the phytohormone abscisic acid (ABA) prior to desiccation, it can survive 24 h exposure to desiccation and regrow after rehydration. The desiccation tolerance induced by ABA (AiDT) is specific to this hormone, but also depends on a plant transcription factor ABSCISIC ACID INSENSITIVE3 (ABI3). Here we report the comparative proteomic analysis of AiDT between wild type and ABI3 deleted mutant (Δabi3) of P. patens using iTRAQ (Isobaric Tags for Relative and Absolute Quantification). From a total of 1980 unique proteins that we identified, only 16 proteins are significantly altered in Δabi3 compared to wild type after desiccation following ABA treatment. Among this group, three of the four proteins that were severely affected in Δabi3 tissue were Arabidopsis orthologous genes, which were expressed in maturing seeds under the regulation of ABI3. These included a Group 1 late embryogenesis abundant (LEA) protein, a short-chain dehydrogenase, and a desiccation-related protein. Our results suggest that at least three of these proteins expressed in desiccation tolerant cells of both Arabidopsis and the moss are very likely to play important roles in acquisition of desiccation tolerance in land plants. Furthermore, our results suggest that the regulatory machinery of ABA- and ABI3-mediated gene expression for desiccation

Cinnamic acid exerts anti-diabetic activity by improving glucose tolerance in vivo and by stimulating insulin secretion in vitro.

PubMed

Hafizur, Rahman M; Hameed, Abdul; Shukrana, Mishkat; Raza, Sayed Ali; Chishti, Sidra; Kabir, Nurul; Siddiqui, Rehan A

2015-02-15

Although the anti-diabetic activity of cinnamic acid, a pure compound from cinnamon, has been reported but its mechanism(s) is not yet clear. The present study was designed to explore the possible mechanism(s) of anti-diabetic activity of cinnamic acid in in vitro and in vivo non-obese type 2 diabetic rats. Non-obese type 2 diabetes was developed by injecting 90 mg/kg streptozotocin in 2-day-old Wistar pups. Cinnamic acid and cinnamaldehyde were administered orally to diabetic rats for assessing acute blood glucose lowering effect and improvement of glucose tolerance. Additionally, insulin secretory activity of cinnamic acid and cinnamaldehyde was evaluated in isolated mice islets. Cinnamic acid, but not cinnamaldehyde, decreased blood glucose levels in diabetic rats in a time- and dose-dependent manner. Oral administration of cinnamic acid with 5 and 10 mg/kg doses to diabetic rats improved glucose tolerance in a dose-dependent manner. The improvement by 10 mg/kg cinnamic acid was comparable to that of standard drug glibenclamide (5 mg/kg). Further in vitro studies showed that cinnamaldehyde has little or no effect on glucose-stimulated insulin secretion; however, cinnamic acid significantly enhanced glucose-stimulated insulin secretion in isolated islets. In conclusion, it can be said that cinnamic acid exerts anti-diabetic activity by improving glucose tolerance in vivo and stimulating insulin secretion in vitro. Copyright © 2015 Elsevier GmbH. All rights reserved.

Role of abscisic acid in strigolactone-induced salt stress tolerance in arbuscular mycorrhizal Sesbania cannabina seedlings.

PubMed

Ren, Cheng-Gang; Kong, Cun-Cui; Xie, Zhi-Hong

2018-05-03

Strigolactones (SLs) are considered to be a novel class of phytohormone involved in plant defense responses. Currently, their relationships with other plant hormones, such as abscisic acid (ABA), during responses to salinity stress are largely unknown. In this study, the relationship between SL and ABA during the induction of H 2 O 2 - mediated tolerance to salt stress were studied in arbuscular mycorrhizal (AM) Sesbania cannabina seedlings. The SL levels increased after ABA treatments and decreased when ABA biosynthesis was inhibited in AM plants. Additionally, the expression levels of SL-biosynthesis genes in AM plants increased following treatments with exogenous ABA and H 2 O 2 . Furthermore, ABA-induced SL production was blocked by a pre-treatment with dimethylthiourea, which scavenges H 2 O 2 . In contrast, ABA production was unaffected by dimethylthiourea. Abscisic acid induced only partial and transient increases in the salt tolerance of TIS108 (a SL synthesis inhibitor) treated AM plants, whereas SL induced considerable and prolonged increases in salt tolerance after a pre-treatment with tungstate. These results strongly suggest that ABA is regulating the induction of salt tolerance by SL in AM S. cannabina seedlings.

40 CFR 180.1019 - Sulfuric acid; exemption from the requirement of a tolerance.

Code of Federal Regulations, 2011 CFR

2011-07-01

... AGENCY (CONTINUED) PESTICIDE PROGRAMS TOLERANCES AND EXEMPTIONS FOR PESTICIDE CHEMICAL RESIDUES IN FOOD... good agricultural practice when used as a herbicide in the production of garlic and onions, and as a... from the use of sulfuric acid as an inert ingredient in a pesticide product used in irrigation...

40 CFR 180.1225 - Decanoic acid; exemption from the requirement of a tolerance.

Code of Federal Regulations, 2010 CFR

2010-07-01

..., breweries, wineries, beverage and food processing plants. [68 FR 7939, Feb. 19, 2003; 68 FR 17308, Apr. 9... AGENCY (CONTINUED) PESTICIDE PROGRAMS TOLERANCES AND EXEMPTIONS FOR PESTICIDE CHEMICAL RESIDUES IN FOOD... acid (up to 170 ppm per application) on food contact surfaces such as equipment, pipelines, tanks, vats...

Considerations in the use of fluorescence in situ hybridization (FISH) and confocal laser scanning microscopy to characterize rumen methanogens and define their spatial distributions.

PubMed

Valle, Edith R; Henderson, Gemma; Janssen, Peter H; Cox, Faith; Alexander, Trevor W; McAllister, Tim A

2015-06-01

In this study, methanogen-specific coenzyme F420 autofluorescence and confocal laser scanning microscopy were used to identify rumen methanogens and define their spatial distribution in free-living, biofilm-, and protozoa-associated microenvironments. Fluorescence in situ hybridization (FISH) with temperature-controlled hybridization was used in an attempt to describe methanogen diversity. A heat pretreatment (65 °C, 1 h) was found to be a noninvasive method to increase probe access to methanogen RNA targets. Despite efforts to optimize FISH, 16S rRNA methanogen-specific probes, including Arch915, bound to some cells that lacked F420, possibly identifying uncharacterized Methanomassiliicoccales or reflecting nonspecific binding to other members of the rumen bacterial community. A probe targeting RNA from the methanogenesis-specific methyl coenzyme M reductase (mcr) gene was shown to detect cultured Methanosarcina cells with signal intensities comparable to those of 16S rRNA probes. However, the probe failed to hybridize with the majority of F420-emitting rumen methanogens, possibly because of differences in cell wall permeability among methanogen species. Methanogens were shown to integrate into microbial biofilms and to exist as ecto- and endosymbionts with rumen protozoa. Characterizing rumen methanogens and defining their spatial distribution may provide insight into mitigation strategies for ruminal methanogenesis.

Recovery of palladium(II) by methanogenic granular sludge.

PubMed

Pat-Espadas, Aurora M; Field, James A; Otero-Gonzalez, Lila; Razo-Flores, Elías; Cervantes, Francisco J; Sierra-Alvarez, Reyes

2016-02-01

This is the first report that demonstrates the ability of anaerobic methanogenic granular sludge to reduce Pd(II) to Pd(0). Different electron donors were evaluated for their effectiveness in promoting Pd reduction. Formate and H2 fostered both chemically and biologically mediated Pd reduction. Ethanol only promoted the reduction of Pd(II) under biotic conditions and the reduction was likely mediated by H2 released from ethanol fermentation. No reduction was observed in biotic or abiotic assays with all other substrates tested (acetate, lactate and pyruvate) although a large fraction of the total Pd was removed from the liquid medium likely due to biosorption. Pd(II) displayed severe inhibition towards acetoclastic and hydrogenotrophic methanogens, as indicated by 50% inhibiting concentrations as low as 0.96 and 2.7 mg/L, respectively. The results obtained indicate the potential of utilizing anaerobic granular sludge bioreactor technology as a practical and promising option for Pd(II) reduction and recovery offering advantages over pure cultures. Copyright © 2015 Elsevier Ltd. All rights reserved.

Screening and characterization of ethanol-tolerant and thermotolerant acetic acid bacteria from Chinese vinegar Pei.

PubMed

Chen, Yang; Bai, Ye; Li, Dongsheng; Wang, Chao; Xu, Ning; Hu, Yong

2016-01-01

Acetic acid bacteria (AAB) are important microorganisms in the vinegar industry. However, AAB have to tolerate the presence of ethanol and high temperatures, especially in submerged fermentation (SF), which inhibits AAB growth and acid yield. In this study, seven AAB that are tolerant to temperatures above 40 °C and ethanol concentrations above 10% (v/v) were isolated from Chinese vinegar Pei. All the isolated AAB belong to Acetobacter pasteurianus according to 16S rDNA analysis. Among all AAB, AAB4 produced the highest acid yield under high temperature and ethanol test conditions. At 4% ethanol and 30-40 °C temperatures, AAB4 maintained an alcohol-acid transform ratio of more than 90.5 %. High alcohol-acid transform ratio was still maintained even at higher temperatures, namely, 87.2, 77.1, 14.5 and 2.9% at 41, 42, 43 and 44 °C, respectively. At 30 °C and different initial ethanol concentrations (4-10%), the acid yield by AAB4 increased gradually, although the alcohol-acid transform ratio decreased to some extent. However, 46.5, 8.7 and 0.9% ratios were retained at ethanol concentrations of 11, 12 and 13%, respectively. When compared with AS1.41 (an AAB widely used in China) using a 10 L fermentor, AAB4 produced 42.0 g/L acetic acid at 37 °C with 10% ethanol, whereas AS1.41 almost stopped producing acetic acid. In conclusion, these traits suggest that AAB4 is a valuable strain for vinegar production in SF.

Quantitative determination of H2-utilizing acetogenic and sulfate-reducing bacteria and methanogenic archaea from digestive tract of different mammals.

PubMed

Morvan, B; Bonnemoy, F; Fonty, G; Gouet, P

1996-03-01

Total number of bacteria, cellulolytic bacteria, and H2-utilizing microbial populations (methanogenic archaea, acetogenic and sulfate-reducing bacteria) were enumerated in fresh rumen samples from sheep, cattle, buffaloes, deer, llamas, and caecal samples from horses. Methanogens and sulfate reducers were found in all samples, whereas acetogenes were not detected in some samples of each animal. Archaea methanogens were the largest H2-utilizing populations in all animals, and a correlation was observed between the numbers of methanogens and those of cellulolytic microorganisms. Higher counts of acetogens were found in horses and llamas (1 x 10(4) and 4 x 10(4) cells ml-1 respectively).

Methanogenic H2 syntrophy among thermophiles: a model of metabolism, adaptation and survival in the subsurface

NASA Astrophysics Data System (ADS)

Topcuoglu, B. D.; Stewart, L. C.; Butterfield, D. A.; Huber, J. A.; Holden, J. F.

2016-12-01

Approximately 1 giga ton (Gt, 1015 g) of CH4 is formed globally per year from H2, CO2 and acetate through methanogenesis, largely by methanogens growing in syntrophic association with anaerobic microbes that hydrolyze and ferment biopolymers. However, our understanding of methanogenesis in hydrothermal regions of the subseafloor and potential syntrophic methanogenesis at thermophilic temperatures (i.e., >50°C) is nascent. In this study, the growth of natural assemblages of thermophilic methanogens from Axial Seamount was primarily limited by H2 availability. Heterotrophs supported thermophilic methanogenesis by H2 syntrophy in microcosm incubations of hydrothermal fluids at 55°C and 80°C supplemented with tryptone only. Based on 16S rRNA gene sequencing, only heterotrophic archaea that produce H2, H2-consuming methanogens, and sulfate reducing archaea were found in 80°C tryptone microcosms from Marker 113 vent. No bacteria were found. In 55°C tryptone microcosms, sequences were found from H2-producing bacteria and H2-consuming methanogens and sulfate-reducing bacteria. In order to model the impact of H2 syntrophy at hyperthemophilic temperatures, a co-culture was established consisting of the H2-producing hyperthermophilic heterotroph Thermococcus paralvinellae and a H2-consuming hyperthermophilic methanogen Methanocaldococcus bathoardescens. When grown alone in a chemostat, the growth rates and steady-state cell concentrations of T. paralvinellae decreased significantly when a high H2 (70 µM) background was present. H2 inhibition was ameliorated by the production of formate, but in silico modeling suggests less energetic yield for the cells. H2 syntrophy relieved H2 inhibition for both the heterotroph and the methanogenic partners. The results demonstrate that thermophilic H2 syntrophy can support methanogenesis within natural microbial assemblages and may be an important alternative energy source for thermophilic autotrophs in marine geothermal environments.

Roles of thermophilic thiosulfate-reducing bacteria and methanogenic archaea in the biocorrosion of oil pipelines

PubMed Central

Liang, Renxing; Grizzle, Robert S.; Duncan, Kathleen E.; McInerney, Michael J.; Suflita, Joseph M.

2014-01-01

Thermophilic sulfide-producing microorganisms from an oil pipeline network were enumerated with different sulfur oxyanions as electron acceptors at 55°C. Most-probable number (MPN) analysis showed that thiosulfate-reducing bacteria were the most numerous sulfidogenic microorganisms in pipeline inspection gauge (PIG) scrapings. Thiosulfate-reducing and methanogenic enrichments were obtained from the MPN cultures that were able to use yeast extract as the electron donor. Molecular analysis revealed that both enrichments harbored the same dominant bacterium, which belonged to the genus Anaerobaculum. The dominant archaeon in the methanogenic enrichment was affiliated with the genus Methanothermobacter. With yeast extract as the electron donor, the general corrosion rate by the thiosulfate-reducing enrichment (8.43 ± 1.40 milli-inch per year, abbreviated as mpy) was about 5.5 times greater than the abiotic control (1.49 ± 0.15 mpy), while the comparable measures for the methanogenic culture were 2.03 ± 0.49 mpy and 0.62 ± 0.07 mpy, respectively. Total iron analysis in the cultures largely accounted for the mass loss of iron measured in the weight loss determinations. Profilometry analysis of polished steel coupons incubated in the presence of the thiosulfate-reducing enrichment revealed 59 pits over an area of 71.16 mm2, while only 6 pits were evident in the corresponding methanogenic incubations. The results show the importance of thiosulfate-utilizing, sulfide-producing fermentative bacteria such as Anaerobaculum sp. in the corrosion of carbon steel, but also suggest that Anaerobaculum sp. are of far less concern when growing syntrophically with methanogens. PMID:24639674

Roles of thermophilic thiosulfate-reducing bacteria and methanogenic archaea in the biocorrosion of oil pipelines.

PubMed

Liang, Renxing; Grizzle, Robert S; Duncan, Kathleen E; McInerney, Michael J; Suflita, Joseph M

2014-01-01

Thermophilic sulfide-producing microorganisms from an oil pipeline network were enumerated with different sulfur oxyanions as electron acceptors at 55°C. Most-probable number (MPN) analysis showed that thiosulfate-reducing bacteria were the most numerous sulfidogenic microorganisms in pipeline inspection gauge (PIG) scrapings. Thiosulfate-reducing and methanogenic enrichments were obtained from the MPN cultures that were able to use yeast extract as the electron donor. Molecular analysis revealed that both enrichments harbored the same dominant bacterium, which belonged to the genus Anaerobaculum. The dominant archaeon in the methanogenic enrichment was affiliated with the genus Methanothermobacter. With yeast extract as the electron donor, the general corrosion rate by the thiosulfate-reducing enrichment (8.43 ± 1.40 milli-inch per year, abbreviated as mpy) was about 5.5 times greater than the abiotic control (1.49 ± 0.15 mpy), while the comparable measures for the methanogenic culture were 2.03 ± 0.49 mpy and 0.62 ± 0.07 mpy, respectively. Total iron analysis in the cultures largely accounted for the mass loss of iron measured in the weight loss determinations. Profilometry analysis of polished steel coupons incubated in the presence of the thiosulfate-reducing enrichment revealed 59 pits over an area of 71.16 mm(2), while only 6 pits were evident in the corresponding methanogenic incubations. The results show the importance of thiosulfate-utilizing, sulfide-producing fermentative bacteria such as Anaerobaculum sp. in the corrosion of carbon steel, but also suggest that Anaerobaculum sp. are of far less concern when growing syntrophically with methanogens.

Comparative analysis of metagenomes from three methanogenic hydrocarbon-degrading enrichment cultures with 41 environmental samples.

PubMed

Tan, Boonfei; Fowler, S Jane; Abu Laban, Nidal; Dong, Xiaoli; Sensen, Christoph W; Foght, Julia; Gieg, Lisa M

2015-09-01

Methanogenic hydrocarbon metabolism is a key process in subsurface oil reservoirs and hydrocarbon-contaminated environments and thus warrants greater understanding to improve current technologies for fossil fuel extraction and bioremediation. In this study, three hydrocarbon-degrading methanogenic cultures established from two geographically distinct environments and incubated with different hydrocarbon substrates (added as single hydrocarbons or as mixtures) were subjected to metagenomic and 16S rRNA gene pyrosequencing to test whether these differences affect the genetic potential and composition of the communities. Enrichment of different putative hydrocarbon-degrading bacteria in each culture appeared to be substrate dependent, though all cultures contained both acetate- and H2-utilizing methanogens. Despite differing hydrocarbon substrates and inoculum sources, all three cultures harbored genes for hydrocarbon activation by fumarate addition (bssA, assA, nmsA) and carboxylation (abcA, ancA), along with those for associated downstream pathways (bbs, bcr, bam), though the cultures incubated with hydrocarbon mixtures contained a broader diversity of fumarate addition genes. A comparative metagenomic analysis of the three cultures showed that they were functionally redundant despite their enrichment backgrounds, sharing multiple features associated with syntrophic hydrocarbon conversion to methane. In addition, a comparative analysis of the culture metagenomes with those of 41 environmental samples (containing varying proportions of methanogens) showed that the three cultures were functionally most similar to each other but distinct from other environments, including hydrocarbon-impacted environments (for example, oil sands tailings ponds and oil-affected marine sediments). This study provides a basis for understanding key functions and environmental selection in methanogenic hydrocarbon-associated communities.

Phylogenetic identification of methanogens assimilating acetate-derived carbon in dairy and swine manures.

PubMed

Barret, Maialen; Gagnon, Nathalie; Morissette, Bruno; Kalmokoff, Martin L; Topp, Edward; Brooks, Stephen P J; Matias, Fernando; Neufeld, Josh D; Talbot, Guylaine

2015-02-01

In order to develop approaches for reducing the carbon footprint of the swine and dairy industries, it is important first to identify the methanogenic communities that drive methane emissions from stored manure. In this study, the metabolically active methanogens in substrate-starved manure samples taken from two dairy and one swine manure storage tanks were identified using [(13)C]-acetate and DNA stable-isotope probing (DNA-SIP). Molecular analysis of recovered genomic [(13)C]-DNA revealed that two distinct clusters of unclassified methanogen populations affiliated with the Methanoculleus genus, and the populations affiliated with Methanoculleus chikugoensis assimilated acetate-derived carbon (acetate-C) in swine and dairy starved manure samples, respectively. Furthermore, carbon flow calculations indicated that these populations were the primary contributors to methane emissions during these anoxic SIP incubations. Comparative analysis of mcrA gene abundance (coding for a key enzyme of methanogenesis) for Methanoculleus spp. in fresh feces and a wider range of stored dairy or swine manure samples, by real-time quantitative PCR using newly designed specific primers, demonstrated that the abundance of this genus significantly increased during storage. The findings supported the involvement of these particular methanogen populations as methane emitters from swine and dairy manure storage tanks. The study revealed that the ability to assimilate acetate-C for growth in manure differed within the Methanoculleus genus. Crown Copyright © 2014. Published by Elsevier GmbH. All rights reserved.

Simultaneous induction of jasmonic acid and disease-responsive genes signifies tolerance of American elm to Dutch elm disease

PubMed Central

Sherif , S. M.; Shukla, M. R.; Murch, S. J.; Bernier, L.; Saxena, P. K.

2016-01-01

Dutch elm disease (DED), caused by three fungal species in the genus Ophiostoma, is the most devastating disease of both native European and North American elm trees. Although many tolerant cultivars have been identified and released, the tolerance mechanisms are not well understood and true resistance has not yet been achieved. Here we show that the expression of disease-responsive genes in reactions leading to tolerance or susceptibility is significantly differentiated within the first 144 hours post-inoculation (hpi). Analysis of the levels of endogenous plant defense molecules such as jasmonic acid (JA) and salicylic acid (SA) in tolerant and susceptible American elm saplings suggested SA and methyl-jasmonate as potential defense response elicitors, which was further confirmed by field observations. However, the tolerant phenotype can be best characterized by a concurrent induction of JA and disease-responsive genes at 96 hpi. Molecular investigations indicated that the expression of fungal genes (i.e. cerato ulmin) was also modulated by endogenous SA and JA and this response was unique among aggressive and non-aggressive fungal strains. The present study not only provides better understanding of tolerance mechanisms to DED, but also represents a first, verified template for examining simultaneous transcriptomic changes during American elm-fungus interactions. PMID:26902398

Factors influencing the degradation of garbage in methanogenic bioreactors and impacts on biogas formation.

PubMed

Morita, Masahiko; Sasaki, Kengo

2012-05-01

Anaerobic digestion of garbage is attracting much attention because of its application in waste volume reduction and the recovery of biogas for use as an energy source. In this review, various factors influencing the degradation of garbage and the production of biogas are discussed. The surface hydrophobicity and porosity of supporting materials are important factors in retaining microorganisms such as aceticlastic methanogens and in attaining a higher degradation of garbage and a higher production of biogas. Ammonia concentration, changes in environmental parameters such as temperature and pH, and adaptation of microbial community to ammonia have been related to ammonia inhibition. The effects of drawing electrons from the methanogenic community and donating electrons into the methanogenic community on methane production have been shown in microbial fuel cells and bioelectrochemical reactors. The influences of trace elements, phase separation, and co-digestion are also summarized in this review.

Fermentation Enhancement of Methanogenic Archaea Consortia from an Illinois Basin Coalbed via DOL Emulsion Nutrition

PubMed Central

Xiao, Dong; Peng, Su-Ping; Wang, En-Yuan

2015-01-01

Microbially enhanced coalbed methane technology must be used to increase the methane content in mining and generate secondary biogenic gas. In this technology, the metabolic processes of methanogenic consortia are the basis for the production of biomethane from some of the organic compounds in coal. Thus, culture nutrition plays an important role in remediating the nutritional deficiency of a coal seam. To enhance the methane production rates for microorganism consortia, different types of nutrition solutions were examined in this study. Emulsion nutrition solutions containing a novel nutritional supplement, called dystrophy optional modification latex, increased the methane yield for methanogenic consortia. This new nutritional supplement can help methanogenic consortia form an enhanced anaerobic environment, optimize the microbial balance in the consortia, and improve the methane biosynthesis rate. PMID:25884952

Salicylic acid-induced abiotic stress tolerance and underlying mechanisms in plants

PubMed Central

Khan, M. Iqbal R.; Fatma, Mehar; Per, Tasir S.; Anjum, Naser A.; Khan, Nafees A.

2015-01-01

Abiotic stresses (such as metals/metalloids, salinity, ozone, UV-B radiation, extreme temperatures, and drought) are among the most challenging threats to agricultural system and economic yield of crop plants. These stresses (in isolation and/or combination) induce numerous adverse effects in plants, impair biochemical/physiological and molecular processes, and eventually cause severe reductions in plant growth, development and overall productivity. Phytohormones have been recognized as a strong tool for sustainably alleviating adverse effects of abiotic stresses in crop plants. In particular, the significance of salicylic acid (SA) has been increasingly recognized in improved plant abiotic stress-tolerance via SA-mediated control of major plant-metabolic processes. However, the basic biochemical/physiological and molecular mechanisms that potentially underpin SA-induced plant-tolerance to major abiotic stresses remain least discussed. Based on recent reports, this paper: (a) overviews historical background and biosynthesis of SA under both optimal and stressful environments in plants; (b) critically appraises the role of SA in plants exposed to major abiotic stresses; (c) cross-talks potential mechanisms potentially governing SA-induced plant abiotic stress-tolerance; and finally (d) briefly highlights major aspects so far unexplored in the current context. PMID:26175738

Cultivation of methanogenic community from subseafloor sediments using a continuous-flow bioreactor

PubMed Central

Imachi, Hiroyuki; Aoi, Ken; Tasumi, Eiji; Saito, Yumi; Yamanaka, Yuko; Saito, Yayoi; Yamaguchi, Takashi; Tomaru, Hitoshi; Takeuchi, Rika; Morono, Yuki; Inagaki, Fumio; Takai, Ken

2011-01-01

Microbial methanogenesis in subseafloor sediments is a key process in the carbon cycle on the Earth. However, the cultivation-dependent evidences have been poorly demonstrated. Here we report the cultivation of a methanogenic microbial consortium from subseafloor sediments using a continuous-flow-type bioreactor with polyurethane sponges as microbial habitats, called down-flow hanging sponge (DHS) reactor. We anaerobically incubated methane-rich core sediments collected from off Shimokita Peninsula, Japan, for 826 days in the reactor at 10 °C. Synthetic seawater supplemented with glucose, yeast extract, acetate and propionate as potential energy sources was provided into the reactor. After 289 days of operation, microbiological methane production became evident. Fluorescence in situ hybridization analysis revealed the presence of metabolically active microbial cells with various morphologies in the reactor. DNA- and RNA-based phylogenetic analyses targeting 16S rRNA indicated the successful growth of phylogenetically diverse microbial components during cultivation in the reactor. Most of the phylotypes in the reactor, once it made methane, were more closely related to culture sequences than to the subsurface environmental sequence. Potentially methanogenic phylotypes related to the genera Methanobacterium, Methanococcoides and Methanosarcina were predominantly detected concomitantly with methane production, while uncultured archaeal phylotypes were also detected. Using the methanogenic community enrichment as subsequent inocula, traditional batch-type cultivations led to the successful isolation of several anaerobic microbes including those methanogens. Our results substantiate that the DHS bioreactor is a useful system for the enrichment of numerous fastidious microbes from subseafloor sediments and will enable the physiological and ecological characterization of pure cultures of previously uncultivated subseafloor microbial life. PMID:21654849

Cultivation of methanogenic community from subseafloor sediments using a continuous-flow bioreactor.

PubMed

Imachi, Hiroyuki; Aoi, Ken; Tasumi, Eiji; Saito, Yumi; Yamanaka, Yuko; Saito, Yayoi; Yamaguchi, Takashi; Tomaru, Hitoshi; Takeuchi, Rika; Morono, Yuki; Inagaki, Fumio; Takai, Ken

2011-12-01

Microbial methanogenesis in subseafloor sediments is a key process in the carbon cycle on the Earth. However, the cultivation-dependent evidences have been poorly demonstrated. Here we report the cultivation of a methanogenic microbial consortium from subseafloor sediments using a continuous-flow-type bioreactor with polyurethane sponges as microbial habitats, called down-flow hanging sponge (DHS) reactor. We anaerobically incubated methane-rich core sediments collected from off Shimokita Peninsula, Japan, for 826 days in the reactor at 10 °C. Synthetic seawater supplemented with glucose, yeast extract, acetate and propionate as potential energy sources was provided into the reactor. After 289 days of operation, microbiological methane production became evident. Fluorescence in situ hybridization analysis revealed the presence of metabolically active microbial cells with various morphologies in the reactor. DNA- and RNA-based phylogenetic analyses targeting 16S rRNA indicated the successful growth of phylogenetically diverse microbial components during cultivation in the reactor. Most of the phylotypes in the reactor, once it made methane, were more closely related to culture sequences than to the subsurface environmental sequence. Potentially methanogenic phylotypes related to the genera Methanobacterium, Methanococcoides and Methanosarcina were predominantly detected concomitantly with methane production, while uncultured archaeal phylotypes were also detected. Using the methanogenic community enrichment as subsequent inocula, traditional batch-type cultivations led to the successful isolation of several anaerobic microbes including those methanogens. Our results substantiate that the DHS bioreactor is a useful system for the enrichment of numerous fastidious microbes from subseafloor sediments and will enable the physiological and ecological characterization of pure cultures of previously uncultivated subseafloor microbial life.

Confocal Raman microspectroscopy reveals a convergence of the chemical composition in methanogenic archaea from a Siberian permafrost-affected soil.

PubMed

Serrano, Paloma; Hermelink, Antje; Lasch, Peter; de Vera, Jean-Pierre; König, Nicole; Burckhardt, Oliver; Wagner, Dirk

2015-12-01

Methanogenic archaea are widespread anaerobic microorganisms responsible for the production of biogenic methane. Several new species of psychrotolerant methanogenic archaea were recently isolated from a permafrost-affected soil in the Lena Delta (Siberia, Russia), showing an exceptional resistance against desiccation, osmotic stress, low temperatures, starvation, UV and ionizing radiation when compared to methanogens from non-permafrost environments. To gain a deeper insight into the differences observed in their resistance, we described the chemical composition of methanogenic strains from permafrost and non-permafrost environments using confocal Raman microspectroscopy (CRM). CRM is a powerful tool for microbial identification and provides fingerprint-like information about the chemical composition of the cells. Our results show that the chemical composition of methanogens from permafrost-affected soils presents a high homology and is remarkably different from strains inhabiting non-permafrost environments. In addition, we performed a phylogenetic reconstruction of the studied strains based on the functional gene mcrA to prove the different evolutionary relationship of the permafrost strains. We conclude that the permafrost methanogenic strains show a convergent chemical composition regardless of their genotype. This fact is likely to be the consequence of a complex adaptive process to the Siberian permafrost environment and might be the reason underlying their resistant nature. © FEMS 2015. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Nitrate decreases ruminal methane production with slight changes to ruminal methanogen composition of nitrate-adapted steers.

PubMed

Zhao, Liping; Meng, Qingxiang; Li, Yan; Wu, Hao; Huo, Yunlong; Zhang, Xinzhuang; Zhou, Zhenming

2018-03-20

This study was conducted to examine effects of nitrate on ruminal methane production, methanogen abundance, and composition. Six rumen-fistulated Limousin×Jinnan steers were fed diets supplemented with either 0% (0NR), 1% (1NR), or 2% (2NR) nitrate (dry matter basis) regimens in succession. Rumen fluid was taken after two-week adaptation for evaluation of in vitro methane production, methanogen abundance, and composition measurements. Results showed that nitrate significantly decreased in vitro ruminal methane production at 6 h, 12 h, and 24 h (P < 0.01; P < 0.01; P = 0.01). The 1NR and 2NR regimens numerically reduced the methanogen population by 4.47% and 25.82% respectively. However, there was no significant difference observed between treatments. The alpha and beta diversity of the methanogen community was not significantly changed by nitrate either. However, the relative abundance of the methanogen genera was greatly changed. Methanosphaera (P L  = 0.0033) and Methanimicrococcus (P L  = 0.0113) abundance increased linearly commensurate with increasing nitration levels, while Methanoplanus abundance was significantly decreased (P L  = 0.0013). The population of Methanoculleus, the least frequently identified genus in this study, exhibited quadratic growth from 0% to 2% when nitrate was added (P Q  = 0.0140). Correlation analysis found that methane reduction was significantly related to Methanobrevibacter and Methanoplanus abundance, and negatively correlated with Methanosphaera and Methanimicrococcus abundance.

Stress management skills in the subsurface: H2 stress on thermophilic heterotrophs and methanogens

NASA Astrophysics Data System (ADS)

Topcuoglu, B. D.; Holden, J. F.

2017-12-01

Marine hyperthermophilic heterotrophs and methanogens belonging to the Thermococcales and Methanococcales are often found in subsurface environments such as coal and shale beds, marine sediments, and oil reservoirs where they encounter H2 stress conditions. It is important to study the H2 stress survival strategies of these organisms and their cooperation with one another for survival to better understand their biogeochemical impact in hot subsurface environments. In this study, we have shown that H2 inhibition changed the growth kinetics and the transcriptome of Thermococcus paralvinellae. We observed a significant decrease in batch phase growth rates and cell concentrations with high H2 background. Produced metabolite production measurements, RNA-seq analyses of differentially expressed genes and in silico experiments we performed with the T. paralvinellae metabolic model showed that T. paralvinellae produces formate by a formate hydrogenlyase to survive H2 inhibition. We have also shown that H2 limitation caused a significant decrease in batch phase growth rates and methane production rates of the methanogen, Methanocaldococcus jannaschii. H2 stress of both organisms can be ameliorated by syntrophic growth. H2 syntrophy was demonstrated in microcosm incubations for a natural assemblage of Thermococcus and hyperthermophilic methanogens present in hydrothermal fluid samples. This project aims to describe how a hyperthermophilic heterotroph and a hyperthermophilic methanogen eliminate H2 stress and explore cooperation among thermophiles in the hot subsurface.

The improvement of the energy resolution in epi-thermal neutron region of Bonner sphere using boric acid water solution moderator.

PubMed

Ueda, H; Tanaka, H; Sakurai, Y

2015-10-01

Bonner sphere is useful to evaluate the neutron spectrum in detail. We are improving the energy resolution in epi-thermal neutron region of Bonner sphere, using boric acid water solution as a moderator. Its response function peak is narrower than that for polyethylene moderator and the improvement of the resolution is expected. The resolutions between polyethylene moderator and boric acid water solution moderator were compared by simulation calculation. Also the influence in the uncertainty of Bonner sphere configuration to spectrum estimation was simulated. Copyright © 2015 Elsevier Ltd. All rights reserved.

Immobilization patterns and dynamics of acetate-utilizing methanogens immobilized in sterile granular sludge in upflow anaerobic sludge blanket reactors.

PubMed

Schmidt, J E; Ahring, B K

1999-03-01

Sterile granular sludge was inoculated with either Methanosarcina mazeii S-6, Methanosaeta concilii GP-6, or both species in acetate-fed upflow anaerobic sludge blanket (UASB) reactors to investigate the immobilization patterns and dynamics of aceticlastic methanogens in granular sludge. After several months of reactor operation, the methanogens were immobilized, either separately or together. The fastest immobilization was observed in the reactor containing M. mazeii S-6. The highest effluent concentration of acetate was observed in the reactor with only M. mazeii S-6 immobilized, while the lowest effluent concentration of acetate was observed in the reactor where both types of methanogens were immobilized together. No changes were observed in the kinetic parameters (Ks and mumax) of immobilized M. concilii GP-6 or M. mazeii S-6 compared with suspended cultures, indicating that immobilization does not affect the growth kinetics of these methanogens. An enzyme-linked immunosorbent assay using polyclonal antibodies against either M. concilii GP-6 or M. mazeii S-6 showed significant variations in the two methanogenic populations in the different reactors. Polyclonal antibodies were further used to study the spatial distribution of the two methanogens. M. concilii GP-6 was immobilized only on existing support material without any specific pattern. M. mazeii S-6, however, showed a different immobilization pattern: large clumps were formed when the concentration of acetate was high, but where the acetate concentration was low this strain was immobilized on support material as single cells or small clumps. The data clearly show that the two aceticlastic methanogens immobilize differently in UASB systems, depending on the conditions found throughout the UASB reactor.

Immobilization Patterns and Dynamics of Acetate-Utilizing Methanogens Immobilized in Sterile Granular Sludge in Upflow Anaerobic Sludge Blanket Reactors

PubMed Central

Schmidt, Jens Ejbye; Ahring, Birgitte Kjær

1999-01-01

Sterile granular sludge was inoculated with either Methanosarcina mazeii S-6, Methanosaeta concilii GP-6, or both species in acetate-fed upflow anaerobic sludge blanket (UASB) reactors to investigate the immobilization patterns and dynamics of aceticlastic methanogens in granular sludge. After several months of reactor operation, the methanogens were immobilized, either separately or together. The fastest immobilization was observed in the reactor containing M. mazeii S-6. The highest effluent concentration of acetate was observed in the reactor with only M. mazeii S-6 immobilized, while the lowest effluent concentration of acetate was observed in the reactor where both types of methanogens were immobilized together. No changes were observed in the kinetic parameters (Ks and μmax) of immobilized M. concilii GP-6 or M. mazeii S-6 compared with suspended cultures, indicating that immobilization does not affect the growth kinetics of these methanogens. An enzyme-linked immunosorbent assay using polyclonal antibodies against either M. concilii GP-6 or M. mazeii S-6 showed significant variations in the two methanogenic populations in the different reactors. Polyclonal antibodies were further used to study the spatial distribution of the two methanogens. M. concilii GP-6 was immobilized only on existing support material without any specific pattern. M. mazeii S-6, however, showed a different immobilization pattern: large clumps were formed when the concentration of acetate was high, but where the acetate concentration was low this strain was immobilized on support material as single cells or small clumps. The data clearly show that the two aceticlastic methanogens immobilize differently in UASB systems, depending on the conditions found throughout the UASB reactor. PMID:10049862

Thermophilic anaerobic degradation of butyrate by a butyrate-utilizing bacterium in coculture and triculture with methanogenic bacteria.

PubMed

Ahring, B K; Westermann, P

1987-02-01

We studied syntrophic butyrate degradation in thermophilic mixed cultures containing a butyrate-degrading bacterium isolated in coculture with Methanobacterium thermoautotrophicum or in triculture with M. thermoautotrophicum and the TAM organism, a thermophilic acetate-utilizing methanogenic bacterium. Butyrate was beta-oxidized to acetate with protons as the electron acceptors. Acetate was used concurrently with its production in the triculture. We found a higher butyrate degradation rate in the triculture, in which both hydrogen and acetate were utilized, than in the coculture, in which acetate accumulated. Yeast extract, rumen fluid, and clarified digestor fluid stimulated butyrate degradation, while the effect of Trypticase was less pronounced. Penicillin G, d-cycloserine, and vancomycin caused complete inhibition of butyrate utilization by the cultures. No growth or degradation of butyrate occurred when 2-bromoethanesulfonic acid or chloroform, specific inhibitors of methanogenic bacteria, was added to the cultures and common electron acceptors such as sulfate, nitrate, and fumarate were not used with butyrate as the electron donor. Addition of hydrogen or oxygen to the gas phase immediately stopped growth and butyrate degradation by the cultures. Butyrate was, however, metabolized at approximately the same rate when hydrogen was removed from the cultures and was metabolized at a reduced rate in the cultures previously exposed to hydrogen.

Degradation of hydrocarbons under methanogenic conditions in different geosystems

NASA Astrophysics Data System (ADS)

Straaten, Nontje; Jiménez García, Núria; Richnow, Hans-Hermann; Krueger, Martin

2014-05-01

With increasing energy demand the search for new resources is becoming increasingly important for the future energy supply. Therefore the knowledge about fossil fuels like oil or natural gas and their extraction should be expanded. Biodegraded oil is found in many reservoirs worldwide. Consequently, it is very important to get insight in the microbial communities and metabolic processes involved in hydrocarbon degradation. Due to the lack of alternative electron acceptors in hydrocarbon-rich geosystems, degradation often takes place under methanogenic conditions. The aim of the present study is to identify the microorganisms and mechanisms involved in the degradation of complex hydrocarbons, like BTEX and polycyclic aromatic hydrocarbons, using culture dependent and independent techniques. For this purpose enrichment cultures from marine sediments, shales, coal and oil reservoirs are monitored for their capability to degrade alkanes and aromatic compounds. Moreover the environmental samples of these different geosystems analysed for evidence for the in situ occurrence of methanogenic oil degradation. The gas geochemical data provided in several cases hints for a recent biological origin of the methane present. First results of the microbial community analysis showed in environmental samples and enrichment cultures the existence of Bacteria known to degrade hydrocarbons. Also a diverse community of methanogenic Archaea could be found in the clone libraries. Additionally, in oil and coal reservoir samples the degradation of model hydrocarbons, e.g. methylnaphthalene, hexadecane and BTEX, to CH4 was confirmed by 13C-labeling. To explore the mechanisms involved in biodegradation, the enrichments as well as the original environmental samples are further analysed for the presence of respective functional genes.

Wide Tolerance to Amino Acids Substitutions In The OCTN1 Ergothioneine Transporter

PubMed Central

Frigeni, Marta; Iacobazzi, Francesco; Yin, Xue; Longo, Nicola

2016-01-01

Background Organic cation transporters transfer solutes with a positive charge across the plasma membrane. The novel organic cation transporter 1 (OCTN1) and 2 (OCTN2) transport ergothioneine and carnitine, respectively. Mutations in the SLC22A5 gene encoding OCTN2 cause primary carnitine deficiency, a recessive disorders resulting in low carnitine levels and defective fatty acid oxidation. Variations in the SLC22A4 gene encoding OCTN1 are associated with rheumatoid arthritis and Crohn disease. Methods Here we evaluate the functional properties of the OCTN1 transporter using chimeric transporters constructed by fusing different portion of the OCTN1 and OCTN2 cDNAs. Their relative abundance and subcellular distribution was evaluated through western blot analysis and confocal microscopy. Results Substitutions of the C-terminal portion of OCTN1 with the correspondent residues of OCTN2 generated chimeric OCTN transporters more active than wild-type OCTN1 in transporting ergothioneine. Additional single amino acid substitutions introduced in chimeric OCTN transporters further increased ergothioneine transport activity. Kinetic analysis indicated that increased transport activity was due to an increased Vmax, with modest changes in Km toward ergothioneine. Conclusions Our results indicate that the OCTN1 transporter is tolerant to extensive amino acid substitutions. This is in sharp contrast to the OCTN2 carnitine transporter that has been selected for high functional activity through evolution, with almost all substitutions reducing carnitine transport activity. General significance The widespread tolerance of OCTN1 to amino acid substitutions suggests that the corresponding SLC22A4 gene may have derived from a recent duplication of the SLC22A5 gene and might not yet have a defined physiological role. PMID:26994919

Changes in methane emission, rumen fermentation, and methanogenic community in response to silage and dry cornstalk diets.

PubMed

Chong, Liu; Zhuping, Zhu; Tongjun, Guo; Yongming, Luo; Hongmin, Dong

2014-06-01

This study aimed to investigate the effect of silage or dry cornstalk diets on methane emission, rumen fermentation, and methanogenic community, and reveal whether the change of methanogenic compositions was related to the methane production. A total of 39 sheep were divided into four groups, fed diets of different concentrate level based on silage or dry cornstalk roughage for 40 days. It was found that, at 20% concentrate level, the sheep fed silage could suppress methanogenesis significantly in contrast with the silage diet (p < 0.05). The ruminal acetate:propionate ratio was 3.17 in the silage-fed sheep significantly lower than 3.78 in the dry cornstalk-fed sheep (p < 0.05), reflecting the effect of fermentation on methane output was related to roughage types. Furthermore, the methanogens was found to be significantly lower abundance (p < 0.05), and showed a different pattern using multivariate statistical analysis in silage-fed sheep. Compared with dry cornstalk diet, silage diet of 20% concentrate reduced methane production, decreased methanogenic abundance, and induced change of Methanobrevibacter composition at strain levels. This study showed variation of methanogenic compositions at strain level and its probable relationship with methane production, and provided microbial information to explain the low methane output when the animals were fed silage. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Improved Tolerance to a New Amino Acid-Based Formula by Infants With Cow's Milk Protein Allergy.

PubMed

Jirapinyo, Pipop; Densupsoontorn, Narumon; Kangwanpornsiri, Channagan; Wongarn, Renu; Tirapongporn, Hathaichanok; Chotipanang, Kwanjai; Phuangphan, Phakkanan

2016-12-01

Prevalence and severity of cow's milk protein allergy (CMA) in infants are increasing. A proportion of infants with CMA still elicit signs and symptoms of CMA while ingesting commercial amino acid-based formulas (AAFs). We propose that protein in glucose polymers (GPs) derived from corn starch in the AAFs might be the cause of intolerance to AAF in some infants. We thus have produced small molecules of GPs from rice starch, eliminating the protein fraction from them, and subsequently used them as the sole source of carbohydrate in a new amino acid-based formula (NAAF). The efficacy of the NAAF was compared with that of an AAF in a double-blind, placebo-controlled food challenge (DBPCFC) in young infants with CMA aged <4 months. Infants consumed each formula for 14 days before switching to the other one. If no respiratory, dermatologic, and gastrointestinal symptom occurred, it was considered tolerance. After the challenge, infants consumed the tolerated formula for 4 weeks to prove real tolerance to that formula. Of 46 infants, 23 were intolerant to the AAF, of whom 7 (30.4%) were also intolerant to the NAAF. Sixteen of the 23 infants who were intolerant to the AAF could tolerate the NAAF ( P < .05). The minimal important difference of decreasing percentage of intolerance to the NAAF was 34.8% compared with the infants who were intolerant to the AAF. The NAAF is better tolerated than a commercially available AAF for the management of infants with CMA.

Adaptive Response and Tolerance to Acetic Acid in Saccharomyces cerevisiae and Zygosaccharomyces bailii: A Physiological Genomics Perspective.

PubMed

Palma, Margarida; Guerreiro, Joana F; Sá-Correia, Isabel

2018-01-01

Acetic acid is an important microbial growth inhibitor in the food industry; it is used as a preservative in foods and beverages and is produced during normal yeast metabolism in biotechnological processes. Acetic acid is also a major inhibitory compound present in lignocellulosic hydrolysates affecting the use of this promising carbon source for sustainable bioprocesses. Although the molecular mechanisms underlying Saccharomyces cerevisiae response and adaptation to acetic acid have been studied for years, only recently they have been examined in more detail in Zygosaccharomyces bailii . However, due to its remarkable tolerance to acetic acid and other weak acids this yeast species is a major threat in the spoilage of acidic foods and beverages and considered as an interesting alternative cell factory in Biotechnology. This review paper emphasizes genome-wide strategies that are providing global insights into the molecular targets, signaling pathways and mechanisms behind S. cerevisiae and Z. bailii tolerance to acetic acid, and extends this information to other weak acids whenever relevant. Such comprehensive perspective and the knowledge gathered in these two yeast species allowed the identification of candidate molecular targets, either for the design of effective strategies to overcome yeast spoilage in acidic foods and beverages, or for the rational genome engineering to construct more robust industrial strains. Examples of successful applications are provided.

Adaptive Response and Tolerance to Acetic Acid in Saccharomyces cerevisiae and Zygosaccharomyces bailii: A Physiological Genomics Perspective

PubMed Central

Palma, Margarida; Guerreiro, Joana F.; Sá-Correia, Isabel

2018-01-01

Acetic acid is an important microbial growth inhibitor in the food industry; it is used as a preservative in foods and beverages and is produced during normal yeast metabolism in biotechnological processes. Acetic acid is also a major inhibitory compound present in lignocellulosic hydrolysates affecting the use of this promising carbon source for sustainable bioprocesses. Although the molecular mechanisms underlying Saccharomyces cerevisiae response and adaptation to acetic acid have been studied for years, only recently they have been examined in more detail in Zygosaccharomyces bailii. However, due to its remarkable tolerance to acetic acid and other weak acids this yeast species is a major threat in the spoilage of acidic foods and beverages and considered as an interesting alternative cell factory in Biotechnology. This review paper emphasizes genome-wide strategies that are providing global insights into the molecular targets, signaling pathways and mechanisms behind S. cerevisiae and Z. bailii tolerance to acetic acid, and extends this information to other weak acids whenever relevant. Such comprehensive perspective and the knowledge gathered in these two yeast species allowed the identification of candidate molecular targets, either for the design of effective strategies to overcome yeast spoilage in acidic foods and beverages, or for the rational genome engineering to construct more robust industrial strains. Examples of successful applications are provided. PMID:29515554

The Cytosolic pH of Individual Saccharomyces cerevisiae Cells Is a Key Factor in Acetic Acid Tolerance

PubMed Central

Fernández-Niño, Miguel; Marquina, Maribel; Swinnen, Steve; Rodríguez-Porrata, Boris

2015-01-01

It was shown recently that individual cells of an isogenic Saccharomyces cerevisiae population show variability in acetic acid tolerance, and this variability affects the quantitative manifestation of the trait at the population level. In the current study, we investigated whether cell-to-cell variability in acetic acid tolerance could be explained by the observed differences in the cytosolic pHs of individual cells immediately before exposure to the acid. Results obtained with cells of the strain CEN.PK113-7D in synthetic medium containing 96 mM acetic acid (pH 4.5) showed a direct correlation between the initial cytosolic pH and the cytosolic pH drop after exposure to the acid. Moreover, only cells with a low initial cytosolic pH, which experienced a less severe drop in cytosolic pH, were able to proliferate. A similar correlation between initial cytosolic pH and cytosolic pH drop was also observed in the more acid-tolerant strain MUCL 11987-9. Interestingly, a fraction of cells in the MUCL 11987-9 population showed initial cytosolic pH values below the minimal cytosolic pH detected in cells of the strain CEN.PK113-7D; consequently, these cells experienced less severe drops in cytosolic pH. Although this might explain in part the difference between the two strains with regard to the number of cells that resumed proliferation, it was observed that all cells from strain MUCL 11987-9 were able to proliferate, independently of their initial cytosolic pH. Therefore, other factors must also be involved in the greater ability of MUCL 11987-9 cells to endure strong drops in cytosolic pH. PMID:26341199

Neutral molecular markers support common origin of aluminium tolerance in three congeneric grass species growing in acidic soils.

PubMed

Contreras, Roberto; Figueiras, Ana M; Gallego, F Javier; Benavente, Elena; Manzaneda, Antonio J; Benito, César

2017-11-01

Aluminium (Al) toxicity is the main abiotic stress limiting plant productivity in acidic soils that are widely distributed among arable lands. Plant species differ in the level of Al resistance showing intraspecific and interspecific variation in many crop species. However, the origin of Al-tolerance is not well known. Three annual species, difficult to distinguish phenotypically and that were until recently misinterpreted as a single complex species under Brachypodium distachyon , have been recently separated into three distinct species: the diploids B. distachyon (2 n = 10) and B. stacei (2 n = 20), and B. hybridum (2 n = 30), the allotetraploid derived from the two diploid species. The aims of this work were to know the origin of Al-tolerance in acidic soil conditions within these three Brachypodium species and to develop new DNA markers for species discrimination. Two multiplex SSR-PCRs allowed to genotype a group of 94 accessions for 17 pentanucleotide microsatellite (SSRs) loci. The variability for 139 inter-microsatellite (ISSRs) markers was also examined. The genetic relationships obtained using those neutral molecular markers (SSRs and ISSRs) support that all Al-tolerant allotetraploid accessions of B. hybridum have a common origin that is related with both geographic location and acidic soils. The possibility that the adaptation to acidic soils caused the isolation of the tolerant B. hybridum populations from the others is discussed. We finally describe a new, easy, DNA barcoding method based in the upstream-intron 1 region of the ALMT1 gene, a tool that is 100 % effective to distinguish among these three Brachypodium species.

Neutral molecular markers support common origin of aluminium tolerance in three congeneric grass species growing in acidic soils

PubMed Central

Contreras, Roberto; Figueiras, Ana M; Gallego, F Javier; Benavente, Elena; Manzaneda, Antonio J

2017-01-01

Abstract Aluminium (Al) toxicity is the main abiotic stress limiting plant productivity in acidic soils that are widely distributed among arable lands. Plant species differ in the level of Al resistance showing intraspecific and interspecific variation in many crop species. However, the origin of Al-tolerance is not well known. Three annual species, difficult to distinguish phenotypically and that were until recently misinterpreted as a single complex species under Brachypodium distachyon, have been recently separated into three distinct species: the diploids B. distachyon (2n = 10) and B. stacei (2n = 20), and B. hybridum (2n = 30), the allotetraploid derived from the two diploid species. The aims of this work were to know the origin of Al-tolerance in acidic soil conditions within these three Brachypodium species and to develop new DNA markers for species discrimination. Two multiplex SSR-PCRs allowed to genotype a group of 94 accessions for 17 pentanucleotide microsatellite (SSRs) loci. The variability for 139 inter-microsatellite (ISSRs) markers was also examined. The genetic relationships obtained using those neutral molecular markers (SSRs and ISSRs) support that all Al-tolerant allotetraploid accessions of B. hybridum have a common origin that is related with both geographic location and acidic soils. The possibility that the adaptation to acidic soils caused the isolation of the tolerant B. hybridum populations from the others is discussed. We finally describe a new, easy, DNA barcoding method based in the upstream-intron 1 region of the ALMT1 gene, a tool that is 100 % effective to distinguish among these three Brachypodium species. PMID:29302302

Metabolic pathway engineering based on metabolomics confers acetic and formic acid tolerance to a recombinant xylose-fermenting strain of Saccharomyces cerevisiae

PubMed Central

2011-01-01

Background The development of novel yeast strains with increased tolerance toward inhibitors in lignocellulosic hydrolysates is highly desirable for the production of bio-ethanol. Weak organic acids such as acetic and formic acids are necessarily released during the pretreatment (i.e. solubilization and hydrolysis) of lignocelluloses, which negatively affect microbial growth and ethanol production. However, since the mode of toxicity is complicated, genetic engineering strategies addressing yeast tolerance to weak organic acids have been rare. Thus, enhanced basic research is expected to identify target genes for improved weak acid tolerance. Results In this study, the effect of acetic acid on xylose fermentation was analyzed by examining metabolite profiles in a recombinant xylose-fermenting strain of Saccharomyces cerevisiae. Metabolome analysis revealed that metabolites involved in the non-oxidative pentose phosphate pathway (PPP) [e.g. sedoheptulose-7-phosphate, ribulose-5-phosphate, ribose-5-phosphate and erythrose-4-phosphate] were significantly accumulated by the addition of acetate, indicating the possibility that acetic acid slows down the flux of the pathway. Accordingly, a gene encoding a PPP-related enzyme, transaldolase or transketolase, was overexpressed in the xylose-fermenting yeast, which successfully conferred increased ethanol productivity in the presence of acetic and formic acid. Conclusions Our metabolomic approach revealed one of the molecular events underlying the response to acetic acid and focuses attention on the non-oxidative PPP as a target for metabolic engineering. An important challenge for metabolic engineering is identification of gene targets that have material importance. This study has demonstrated that metabolomics is a powerful tool to develop rational strategies to confer tolerance to stress through genetic engineering. PMID:21219616

Methanogenic biodegradation of creosote contaminants in natural and simulated ground-water ecosystems

USGS Publications Warehouse

Godsy, E. Michael; Goerlitz, Donald; Grbic-Galic, Dunja

1992-01-01

Wastes from a wood preserving plant in Pensacola, Florida have contaminated the near-surface sand-and-gravel aquifer with creosote-derived compounds and pentachlorophenol. Contamination resulted from the discharge of plant waste waters to and subsequent seepage from unlined surface impoundments that were in direct hydraulic contact with the ground water. Two distinct phases resulted when the creosote and water mixed: a denser than water hydrocarbon phase that moved vertically downward, and an organic-rich aqueous phase that moved laterally with the ground-water flow. The aqueous phase is enriched in organic acids, phenolic compounds, single- and double-ring nitrogen, sulfur, and oxygen containing compounds, and single- and double-ring aromatic hydrocarbons. The ground water is devoid of dissolved O2, is 60-70% saturated with CH4 and contains H2S. Field analyses document a greater decrease in concentration of organic fatty acids, benzoic acid, phenol, 2-, 3-, 4-methylphenol, quinoline, isoquinoline, 1(2H)-quinolinone, and 2(1H)-isoquinolinone during downgradient movement in the aquifer than could be explained by dilution and/or dispersion. Laboratory microcosm studies have shown that within the study region, this effect can be attributed to microbial degradation to CH4 and CO2. A small but active methanogenic population was found on sediment materials taken from highly contaminated parts of the aquifer.

Zero-valent iron enhanced methanogenic activity in anaerobic digestion of waste activated sludge after heat and alkali pretreatment.

PubMed

Zhang, Yaobin; Feng, Yinghong; Quan, Xie

2015-04-01

Heat or alkali pretreatment is the effective method to improve hydrolysis of waste sludge and then enhance anaerobic sludge digestion. However the pretreatment may inactivate the methanogens in the sludge. In the present work, zero-valent iron (ZVI) was used to enhance the methanogenic activity in anaerobic sludge digester under two methanogens-suppressing conditions, i.e. heat-pretreatment and alkali condition respectively. With the addition of ZVI, the lag time of methane production was shortened, and the methane yield increased by 91.5% compared to the control group. The consumption of VFA was accelerated by ZVI, especially for acetate, indicating that the acetoclastic methanogenesis was enhanced. In the alkali-condition experiment, the hydrogen produced decreased from 27.6 to 18.8 mL when increasing the ZVI dosage from 0 to 10 g/L. Correspondingly, the methane yield increased from 1.9 to 32.2 mL, which meant that the H2-utilizing methanogenes was enriched. These results suggested that the addition of ZVI into anaerobic digestion of sludge after pretreated by the heat or alkali process could efficiently recover the methanogenic activity and increase the methane production and sludge reduction. Copyright © 2015 Elsevier Ltd. All rights reserved.

Conductive iron oxide minerals accelerate syntrophic cooperation in methanogenic benzoate degradation.

PubMed

Zhuang, Li; Tang, Jia; Wang, Yueqiang; Hu, Min; Zhou, Shungui

2015-08-15

Recent studies have suggested that conductive iron oxide minerals can facilitate syntrophic metabolism of the methanogenic degradation of organic matter, such as ethanol, propionate and butyrate, in natural and engineered microbial ecosystems. This enhanced syntrophy involves direct interspecies electron transfer (DIET) powered by microorganisms exchanging metabolic electrons through electrically conductive minerals. Here, we evaluated the possibility that conductive iron oxides (hematite and magnetite) can stimulate the methanogenic degradation of benzoate, which is a common intermediate in the anaerobic metabolism of aromatic compounds. The results showed that 89-94% of the electrons released from benzoate oxidation were recovered in CH4 production, and acetate was identified as the only carbon-bearing intermediate during benzoate degradation. Compared with the iron-free controls, the rates of methanogenic benzoate degradation were enhanced by 25% and 53% in the presence of hematite and magnetite, respectively. This stimulatory effect probably resulted from DIET-mediated methanogenesis in which electrons transfer between syntrophic partners via conductive iron minerals. Phylogenetic analyses revealed that Bacillaceae, Peptococcaceae, and Methanobacterium are potentially involved in the functioning of syntrophic DIET. Considering the ubiquitous presence of iron minerals within soils and sediments, the findings of this study will increase the current understanding of the natural biological attenuation of aromatic hydrocarbons in anaerobic environments. Copyright © 2015 Elsevier B.V. All rights reserved.

Application of stable isotope measurements and microbiological analysis for detecting methanogenic activity in a temperate forest wetland

NASA Astrophysics Data System (ADS)

Itoh, M.; Katsuyama, C.; Kondo, N.; Ohte, N.; Kato, K.

2009-12-01

Generally, forest soils act as a sink for methane (CH4). However, wetlands in riparian zones are recently reported to be “hot spots” of CH4 emissions, especially in forests under a humid climate. To understand how environmental conditions (i.e. hydrological and/or geomorphic condition) control on CH4 production, we investigated both methanogenic pathways (CO2/H2 reduction and acetate fermentation) and metahanogenic microbial communities in a wetland in a temperate forest catchment, central Japan. We used stable carbon isotopic analysis for detecting change in methanogenic pathways, and applied microbiological analysis for understanding the structure of methanogenic community. CH4 emission rates in wetland were strongly dependent on soil temperatures, and were highest in summer and lowest in winter. δ13CO2 increased with CH4 production in every summer, suggesting preferential use of 12CO2 as substrate for CO2/H2 reduction methanogenesis during high CH4 production period. δ13CH4 also increased in summer with δ13CO2. δ13CH4 changed more wildly than δ13CO2 did in summer with normal precipitation when CH4 production was strongly activated under high temperature and high groundwater table condition. This indicates increase in acetoclastic methanogenesis under hot and wet condition, considering that acetclastic methnogens produce heavier CH4 than that from CO2/H2 reducing pathway. Methanogen community composition estimated by cloning and sequence analyses implied that both acetoclastic and CO2/H2 reducing methanogens prevailed in wetland soil sampled in summer. This was consistent with the results of isotope measuremaents. Our results contribute to understand fully how the CH4 production changes with environmental conditions, with considering the activities of both main methanogenic pathway (from CO2 and acetate).

Efficient production of L-lactic acid by newly isolated thermophilic Bacillus coagulans WCP10-4 with high glucose tolerance.

PubMed

Zhou, Xingding; Ye, Lidan; Wu, Jin Chuan

2013-05-01

A thermophilic Bacillus coagulans WCP10-4 with tolerance to high concentration of glucose was isolated from soil and used to produce optically pure L-lactic acid from glucose and starch. In batch fermentation at pH 6.0, 240 g/L of glucose was completely consumed giving 210 g/L of L-lactic acid with a yield of 95 % and a productivity of 3.5 g/L/h. In simultaneous saccharification and fermentation at 50 °C without sterilizing the medium, 200 g/L of corn starch was completely consumed producing 202.0 g/L of L-lactic acid. To the best of our knowledge, this strain shows the highest osmotic tolerance to glucose among the strains ever reported for lactic acid production. This is the first report of simultaneous saccharification and fermentation of starch for lactic acid production under a non-sterilized condition.

Methanogenic population dynamics during startup of a full-scale anaerobic sequencing batch reactor treating swine waste.

PubMed

Angenent, Largus T; Sung, Shihwu; Raskin, Lutgarde

2002-11-01

Changes in methanogenic population levels were followed during startup of a full-scale, farm-based anaerobic sequencing batch reactor (ASBR) and these changes were linked to operational and performance data. The ASBR was inoculated with anaerobic digester sludge from a municipal wastewater treatment facility. During an acclimation period of approximately 3 months, the ASBR content was diluted to maintain a total ammonia-N level of approximately 2000mg l(-1). After this acclimation period, the volatile solids loading rate was increased to its design value of 1.7g l(-1) day(-1) with a 15-day hydraulic retention time, which increased the total ammonia-N level in the ASBR to approximately 3,600 mg l(-1). The 16S ribosomal RNA (rRNA) levels of the acetate-utilizing methanogens of the genus Methanosarcina decreased from 3.8% to 1.2% (expressed as a percentage of the total 16S rRNA levels) during this period, while the 16S rRNA levels of Methanosaeta concilii remained low (below 2.2%). Methane production and reactor performance were not affected as the 16S rRNA levels of the hydrogen-utilizing methanogens of the order Methanomicrobiales increased from 2.3% to 7.0%. Hence, it is likely that during operation with high ammonia levels, the major route of methane production is through a syntrophic relationship between acetate-oxidizing bacteria and hydrogen-utilizing methanogens. Anaerobic digestion at total ammonia-N levels exceeding 3500mg l(-1) was sustainable apparently due to the acclimation of hydrogen-utilizing methanogens to high ammonia levels.

Effects of short-term acid and aluminum exposure on the parr-smolt transformation in Atlantic salmon (Salmo salar): Disruption of seawater tolerance and endocrine status

USGS Publications Warehouse

Monette, M.Y.; Bjornsson, Bjorn Thrandur; McCormick, S.D.

2008-01-01

Episodic acidification resulting in increased acidity and inorganic aluminum (Ali) is known to interfere with the parr-smolt transformation of Atlantic salmon (Salmo salar), and has been implicated as a possible cause of population decline. To determine the extent and mechanism(s) by which short-term acid/Al exposure compromises smolt development, Atlantic salmon smolts were exposed to either control (pH 6.7-6.9) or acid/Al (pH 5.4-6.3, 28-64 ??g l-1 Ali) conditions for 2 and 5 days, and impacts on freshwater (FW) ion regulation, seawater (SW) tolerance, plasma hormone levels and stress response were examined. Gill Al concentrations were elevated in all smolts exposed to acid/Al relative to controls confirming exposure to increased Ali. There was no effect of acid/Al on plasma ion concentrations in FW however, smolts exposed to acid/Al followed by a 24 h SW challenge exhibited greater plasma Cl- levels than controls, indicating reduced SW tolerance. Loss of SW tolerance was accompanied by reductions in gill Na+,K+-ATPase (NKA) activity and Na+,K+,2Cl- (NKCC) cotransporter protein abundance. Acid/Al exposure resulted in decreased plasma insulin-like growth factor (IGF-I) and 3,3???,5???-triiodo-l-thyronine (T3) levels, whereas no effect of treatment was seen on plasma cortisol, growth hormone (GH), or thyroxine (T4) levels. Acid/Al exposure resulted in increased hematocrit and plasma glucose levels in FW, but both returned to control levels after 24 h in SW. The results indicate that smolt development and SW tolerance are compromised by short-term exposure to acid/Al in the absence of detectable impacts on FW ion regulation. Loss of SW tolerance during short-term acid/Al exposure likely results from reductions in gill NKA and NKCC, possibly mediated by decreases in plasma IGF-I and T3. ?? 2008 Elsevier Inc.

Integrated phospholipidomics and transcriptomics analysis of Saccharomyces cerevisiae with enhanced tolerance to a mixture of acetic acid, furfural, and phenol

USDA-ARS?s Scientific Manuscript database

A mixture of acetic acid, furfural and phenol (AFP), three representative lignocellulose derived inhibitors, significantly inhibited the growth and bioethanol production of Saccharomyces cerevisiae. In order to uncover mechanisms behind the enhanced tolerance of an inhibitor-tolerant S.cerevisiae s...

The efficacy and tolerability of enalapril--hydrochlorothiazide combination as a first line therapy in black patients with mild to moderate arterial hypertension: a clinical study in Kenya.

PubMed

Lore, W; Muita, A K; Ogola, E S

1992-01-01

The study aimed at evaluating tolerability and efficacy of the combination enalapril 20 mg with hydrochlorothiazide 12.5 mg (co-renitec) as first line therapy in black patients with mild to moderate primary hypertension. Fifty patients completed a twelve weeks of open clinical study preceded by two weeks of washout period. They were evaluated every four weeks and haematological, biochemical urine microscopy and electrocardiographic tests were undertaken before the start and after the completion of study. Pre-treatment values of mean systolic blood pressure (SBP) and diastolic blood pressure (DBP) were 172.16 mm hg (+/- 20.41) and 104.38 mm hg (+/- 7.339) respectively. The usual daily dosage was one tablet which was increased to two after eight weeks in case the DBP was not normalized, i.e. less than or equal to 95 mm hg. In 44 (88%) patients, the DBP was normalised at the end of the study period; three patients (6%) were resistant to treatment and another three (6%) exhibited labile response to the treatment. Clinical tolerance was considered to be very good with only five episodes of headache, backache and anxiety, probably not related to the test drug. Biological tolerance was excellent: there was no change in the haematologic parameters; there was a decrease of 5% in mean blood urea, of 9% in the mean serum creatinine and of 4% in the mean serum uric acid and a 5% increase in plasma potassium from 3.99 to 4.28 mmol/l.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of saturated fatty acid-rich dietary vegetable oils on lipid profile, antioxidant enzymes and glucose tolerance in diabetic rats

PubMed Central

Kochikuzhyil, Benson Mathai; Devi, Kshama; Fattepur, Santosh Raghunandan

2010-01-01

Objective: To study the effect of saturated fatty acid (SFA)-rich dietary vegetable oils on the lipid profile, endogenous antioxidant enzymes and glucose tolerance in type 2 diabetic rats. Materials and Methods: Type 2 diabetes was induced by administering streptozotocin (90 mg/kg, i.p.) in neonatal rats. Twenty-eight-day-old normal (N) and diabetic (D) male Wistar rats were fed for 45 days with a fat-enriched special diet (10%) prepared with coconut oil (CO) – lauric acid-rich SFA, palm oil (PO) – palmitic acid-rich SFA and groundnut oil (GNO) – control (N and D). Lipid profile, endogenous antioxidant enzymes and oral glucose tolerance tests were monitored. Results: D rats fed with CO (D + CO) exhibited a significant decrease in the total cholesterol and non-high-density lipoprotein cholesterol. Besides, they also showed a trend toward improving antioxidant enzymes and glucose tolerance as compared to the D + GNO group, whereas D + PO treatment aggravated the dyslipidemic condition while causing a significant decrease in the superoxide dismutase levels when compared to N rats fed with GNO (N + GNO). D + PO treatment also impaired the glucose tolerance when compared to N + GNO and D + GNO. Conclusion: The type of FA in the dietary oil determines its deleterious or beneficial effects. Lauric acid present in CO may protect against diabetes-induced dyslipidemia. PMID:20871763

Methanogenic activity tests by Infrared Tunable Diode Laser Absorption Spectroscopy.

PubMed

Martinez-Cruz, Karla; Sepulveda-Jauregui, Armando; Escobar-Orozco, Nayeli; Thalasso, Frederic

2012-10-01

Methanogenic activity (MA) tests are commonly carried out to estimate the capability of anaerobic biomass to treat effluents, to evaluate anaerobic activity in bioreactors or natural ecosystems, or to quantify inhibitory effects on methanogenic activity. These activity tests are usually based on the measurement of the volume of biogas produced by volumetric, pressure increase or gas chromatography (GC) methods. In this study, we present an alternative method for non-invasive measurement of methane produced during activity tests in closed vials, based on Infrared Tunable Diode Laser Absorption Spectroscopy (MA-TDLAS). This new method was tested during model acetoclastic and hydrogenotrophic methanogenic activity tests and was compared to a more traditional method based on gas chromatography. From the results obtained, the CH(4) detection limit of the method was estimated to 60 ppm and the minimum measurable methane production rate was estimated to 1.09(.)10(-3) mg l(-1) h(-1), which is below CH(4) production rate usually reported in both anaerobic reactors and natural ecosystems. Additionally to sensitivity, the method has several potential interests compared to more traditional methods among which short measurements time allowing the measurement of a large number of MA test vials, non-invasive measurements avoiding leakage or external interferences and similar cost to GC based methods. It is concluded that MA-TDLAS is a promising method that could be of interest not only in the field of anaerobic digestion but also, in the field of environmental ecology where CH(4) production rates are usually very low. Copyright © 2012 Elsevier B.V. All rights reserved.

The CgHaa1-Regulon Mediates Response and Tolerance to Acetic Acid Stress in the Human Pathogen Candida glabrata

PubMed Central

Bernardo, Ruben T.; Cunha, Diana V.; Wang, Can; Pereira, Leonel; Silva, Sónia; Salazar, Sara B.; Schröder, Markus S.; Okamoto, Michiyo; Takahashi-Nakaguchi, Azusa; Chibana, Hiroji; Aoyama, Toshihiro; Sá-Correia, Isabel; Azeredo, Joana; Butler, Geraldine; Mira, Nuno Pereira

2016-01-01

To thrive in the acidic vaginal tract, Candida glabrata has to cope with high concentrations of acetic acid. The mechanisms underlying C. glabrata tolerance to acetic acid at low pH remain largely uncharacterized. In this work, the essential role of the CgHaa1 transcription factor (encoded by ORF CAGL0L09339g) in the response and tolerance of C. glabrata to acetic acid is demonstrated. Transcriptomic analysis showed that CgHaa1 regulates, directly or indirectly, the expression of about 75% of the genes activated under acetic acid stress. CgHaa1-activated targets are involved in multiple physiological functions including membrane transport, metabolism of carbohydrates and amino acids, regulation of the activity of the plasma membrane H+-ATPase, and adhesion. Under acetic acid stress, CgHaa1 increased the activity and the expression of the CgPma1 proton pump and contributed to increased colonization of vaginal epithelial cells by C. glabrata. CgHAA1, and two identified CgHaa1-activated targets, CgTPO3 and CgHSP30, are herein demonstrated to be determinants of C. glabrata tolerance to acetic acid. The protective effect of CgTpo3 and of CgHaa1 was linked to a role of these proteins in reducing the accumulation of acetic acid inside C. glabrata cells. In response to acetic acid stress, marked differences were found in the regulons controlled by CgHaa1 and by its S. cerevisiae ScHaa1 ortholog, demonstrating a clear divergent evolution of the two regulatory networks. The results gathered in this study significantly advance the understanding of the molecular mechanisms underlying the success of C. glabrata as a vaginal colonizer. PMID:27815348

Non-destructive Determination of Shikimic Acid Concentration in Transgenic Maize Exhibiting Glyphosate Tolerance Using Chlorophyll Fluorescence and Hyperspectral Imaging

PubMed Central

Feng, Xuping; Yu, Chenliang; Chen, Yue; Peng, Jiyun; Ye, Lanhan; Shen, Tingting; Wen, Haiyong; He, Yong

2018-01-01

The development of transgenic glyphosate-tolerant crops has revolutionized weed control in crops in many regions of the world. The early, non-destructive identification of superior plant phenotypes is an important stage in plant breeding programs. Here, glyphosate-tolerant transgenic maize and its parental wild-type control were studied at 2, 4, 6, and 8 days after glyphosate treatment. Visible and near-infrared hyperspectral imaging and chlorophyll fluorescence imaging techniques were applied to monitor the performance of plants. In our research, transgenic maize, which was highly tolerant to glyphosate, was phenotyped using these high-throughput non-destructive methods to validate low levels of shikimic acid accumulation and high photochemical efficiency of photosystem II as reflected by maximum quantum yield and non-photochemical quenching in response to glyphosate. For hyperspectral imaging analysis, the combination of spectroscopy and chemometric methods was used to predict shikimic acid concentration. Our results indicated that a partial least-squares regression model, built on optimal wavelengths, effectively predicted shikimic acid concentrations, with a coefficient of determination value of 0.79 for the calibration set, and 0.82 for the prediction set. Moreover, shikimic acid concentration estimates from hyperspectral images were visualized on the prediction maps by spectral features, which could help in developing a simple multispectral imaging instrument for non-destructive phenotyping. Specific physiological effects of glyphosate affected the photochemical processes of maize, which induced substantial changes in chlorophyll fluorescence characteristics. A new data-driven method, combining mean fluorescence parameters and featuring a screening approach, provided a satisfactory relationship between fluorescence parameters and shikimic acid content. The glyphosate-tolerant transgenic plants can be identified with the developed discrimination model

Non-destructive Determination of Shikimic Acid Concentration in Transgenic Maize Exhibiting Glyphosate Tolerance Using Chlorophyll Fluorescence and Hyperspectral Imaging.

PubMed

Feng, Xuping; Yu, Chenliang; Chen, Yue; Peng, Jiyun; Ye, Lanhan; Shen, Tingting; Wen, Haiyong; He, Yong

2018-01-01

The development of transgenic glyphosate-tolerant crops has revolutionized weed control in crops in many regions of the world. The early, non-destructive identification of superior plant phenotypes is an important stage in plant breeding programs. Here, glyphosate-tolerant transgenic maize and its parental wild-type control were studied at 2, 4, 6, and 8 days after glyphosate treatment. Visible and near-infrared hyperspectral imaging and chlorophyll fluorescence imaging techniques were applied to monitor the performance of plants. In our research, transgenic maize, which was highly tolerant to glyphosate, was phenotyped using these high-throughput non-destructive methods to validate low levels of shikimic acid accumulation and high photochemical efficiency of photosystem II as reflected by maximum quantum yield and non-photochemical quenching in response to glyphosate. For hyperspectral imaging analysis, the combination of spectroscopy and chemometric methods was used to predict shikimic acid concentration. Our results indicated that a partial least-squares regression model, built on optimal wavelengths, effectively predicted shikimic acid concentrations, with a coefficient of determination value of 0.79 for the calibration set, and 0.82 for the prediction set. Moreover, shikimic acid concentration estimates from hyperspectral images were visualized on the prediction maps by spectral features, which could help in developing a simple multispectral imaging instrument for non-destructive phenotyping. Specific physiological effects of glyphosate affected the photochemical processes of maize, which induced substantial changes in chlorophyll fluorescence characteristics. A new data-driven method, combining mean fluorescence parameters and featuring a screening approach, provided a satisfactory relationship between fluorescence parameters and shikimic acid content. The glyphosate-tolerant transgenic plants can be identified with the developed discrimination model

Methanogen Diversity in Indigenous and Introduced Ruminant Species on the Tibetan Plateau

PubMed Central

Huang, Xiao Dan; Martinez-Fernandez, Gonzalo; Padmanabha, Jagadish; Long, Ruijun; Denman, Stuart E.; McSweeney, Christopher S.

2016-01-01

Host factors are regarded as important in shaping the archaeal community in the rumen but few controlled studies have been performed to demonstrate this across host species under the same environmental conditions. A study was designed to investigate the structure of the methanogen community in the rumen of two indigenous (yak and Tibetan sheep) and two introduced domestic ruminant (cattle and crossbred sheep) species raised and fed under similar conditions on the high altitude Tibetan Plateau. The methylotrophic Methanomassiliicoccaceae was the predominant archaeal group in all animals even though Methanobrevibacter are usually present in greater abundance in ruminants globally. Furthermore, within the Methanomassiliicoccaceae family members from Mmc. group 10 and Mmc. group 4 were dominant in Tibetan Plateau ruminants compared to Mmc. group 12 found to be highest in other ruminants studied. Small ruminants presented the highest number of sequences that belonged to Methanomassiliicoccaceae compared to the larger ruminants. Although the methanogen community structure was different among the ruminant species, there were striking similarities between the animals in this environment. This indicates that factors such as the extreme environmental conditions and diet on the Tibetan Plateau might have a greater impact on rumen methanogen community compared to host differences. PMID:27274707

Toward the identification of methanogenic archaeal groups as targets of methane mitigation in livestock animalsr

PubMed Central

St-Pierre, Benoit; Cersosimo, Laura M.; Ishaq, Suzanne L.; Wright, André-Denis G.

2015-01-01

In herbivores, enteric methane is a by-product from the digestion of plant biomass by mutualistic gastrointestinal tract (GIT) microbial communities. Methane is a potent greenhouse gas that is not assimilated by the host and is released into the environment where it contributes to climate change. Since enteric methane is exclusively produced by methanogenic archaea, the investigation of mutualistic methanogen communities in the GIT of herbivores has been the subject of ongoing research by a number of research groups. In an effort to uncover trends that would facilitate the development of efficient methane mitigation strategies for livestock species, we have in this review summarized and compared currently available results from published studies on this subject. We also offer our perspectives on the importance of pursuing current research efforts on the sequencing of gut methanogen genomes, as well as investigating their cellular physiology and interactions with other GIT microorganisms. PMID:26284054

Alpha-lipoic acid treatment of acetaminophen-induced rat liver damage.

PubMed

Mahmoud, Y I; Mahmoud, A A; Nassar, G

2015-01-01

Acetaminophen (paracetamol) is a well-tolerated analgesic and antipyretic drug when used at therapeutic doses. Overdoses, however, cause oxidative stress, which leads to acute liver failure. Alpha lipoic acid is an antioxidant that has proven effective for ameliorating many pathological conditions caused by oxidative stress. We evaluated the effect of alpha lipoic acid on the histological and histochemical alterations of liver caused by an acute overdose of acetaminophen in rats. Livers of acetaminophen-intoxicated rats were congested and showed centrilobular necrosis, vacuolar degeneration and inflammatory cell infiltration. Necrotic hepatocytes lost most of their carbohydrates, lipids and structural proteins. Liver sections from rats pre-treated with lipoic acid showed fewer pathological changes; the hepatocytes appeared moderately vacuolated with moderate staining of carbohydrates and proteins. Nevertheless, alpha lipoic acid at the dose we used did not protect the liver fully from acetaminophen-induced acute toxicity.

Trace Elements Affect Methanogenic Activity and Diversity in Enrichments from Subsurface Coal Bed Produced Water

PubMed Central

Ünal, Burcu; Perry, Verlin Ryan; Sheth, Mili; Gomez-Alvarez, Vicente; Chin, Kuk-Jeong; Nüsslein, Klaus

2012-01-01

Microbial methane from coal beds accounts for a significant and growing percentage of natural gas worldwide. Our knowledge of physical and geochemical factors regulating methanogenesis is still in its infancy. We hypothesized that in these closed systems, trace elements (as micronutrients) are a limiting factor for methanogenic growth and activity. Trace elements are essential components of enzymes or cofactors of metabolic pathways associated with methanogenesis. This study examined the effects of eight trace elements (iron, nickel, cobalt, molybdenum, zinc, manganese, boron, and copper) on methane production, on mcrA transcript levels, and on methanogenic community structure in enrichment cultures obtained from coal bed methane (CBM) well produced water samples from the Powder River Basin, Wyoming. Methane production was shown to be limited both by a lack of additional trace elements as well as by the addition of an overly concentrated trace element mixture. Addition of trace elements at concentrations optimized for standard media enhanced methane production by 37%. After 7 days of incubation, the levels of mcrA transcripts in enrichment cultures with trace element amendment were much higher than in cultures without amendment. Transcript levels of mcrA correlated positively with elevated rates of methane production in supplemented enrichments (R2 = 0.95). Metabolically active methanogens, identified by clone sequences of mcrA mRNA retrieved from enrichment cultures, were closely related to Methanobacterium subterraneum and Methanobacterium formicicum. Enrichment cultures were dominated by M. subterraneum and had slightly higher predicted methanogenic richness, but less diversity than enrichment cultures without amendments. These results suggest that varying concentrations of trace elements in produced water from different subsurface coal wells may cause changing levels of CBM production and alter the composition of the active methanogenic community. PMID

SAFETY AND TOLERABILITY OF LOW DOSE NALTREXONE THERAPY IN CHILDREN WITH MODERATE TO SEVERE CROHN’S DISEASE: A PILOT STUDY

PubMed Central

Smith, Jill P.; Field, Douglas; Bingaman, Sandra; Evans, Robert; Mauger, David

2012-01-01

Background There is an unmet need for safe and effective medicines to treat children with Crohn’s disease. Recently, investigations have shown an association between endogenous opioid peptides and inflammatory cells. Aims The aims of this study were to evaluate the safety and tolerability of an opioid antagonist, naltrexone, in children with moderate to severe Crohn’s disease. Methods A pilot clinical trial was conducted in children with moderate to severe Crohn’s disease. Fourteen subjects with a mean age of 12.3 years (8–17, range) were enrolled. Children were randomized to placebo or naltrexone 0.1 mg/kg orally for 8 weeks followed by open-labeled treatment with 8 additional weeks of naltrexone. Safety and toxicity were monitored by physical examinations and blood chemistries. Clinical activity was assessed by the PCDAI (Pediatric Crohn’s Disease Activity Index) and Quality of life was monitored by the Impact III survey. Results Oral naltrexone was well tolerated without any serious adverse events in children with moderate to severe Crohn’s disease. PCDAI scores significantly decreased from pretreatment values (34.2±3.3) with an eight-week course of naltrexone therapy (21.7±3.9) (p=0.005). Twenty-five percent of those treated with naltrexone were considered in remission (score < 10) and 67% had improved with mild disease activity (decrease PCDAI score by at least 10 points) at the end of the study. Systemic and social quality of life improved with naltrexone treatment (p=0.035). Conclusions Naltrexone therapy appears safe with limited toxicity when given to children with Crohn’s disease and may reduce disease activity. PMID:23188075

Response of a rice paddy soil methanogen to syntrophic growth as revealed by transcriptional analyses.

PubMed

Liu, Pengfei; Yang, Yanxiang; Lü, Zhe; Lu, Yahai

2014-08-01

Members of Methanocellales are widespread in paddy field soils and play the key role in methane production. These methanogens feature largely in these organisms’ adaptation to low H2 and syntrophic growth with anaerobic fatty acid oxidizers. The adaptive mechanisms, however, remain unknown. In the present study, we determined the transcripts of 21 genes involved in the key steps of methanogenesis and acetate assimilation of Methanocella conradii HZ254, a strain recently isolated from paddy field soil. M. conradii was grown in monoculture and syntrophically with Pelotomaculum thermopropionicum (a propionate syntroph) or Syntrophothermus lipocalidus (a butyrate syntroph). Comparison of the relative transcript abundances showed that three hydrogenase-encoding genes and all methanogenesis-related genes tested were upregulated in cocultures relative to monoculture. The genes encoding formylmethanofuran dehydrogenase (Fwd), heterodisulfide reductase (Hdr), and the membrane-bound energy-converting hydrogenase (Ech) were the most upregulated among the evaluated genes. The expression of the formate dehydrogenase (Fdh)-encoding gene also was significantly upregulated. In contrast, an acetate assimilation gene was downregulated in cocultures. The genes coding for Fwd, Hdr, and the D subunit of F420-nonreducing hydrogenase (Mvh) form a large predicted transcription unit; therefore, the Mvh/Hdr/Fwd complex, capable of mediating the electron bifurcation and connecting the first and last steps of methanogenesis, was predicted to be formed in M. conradii. We propose that Methanocella methanogens cope with low H2 and syntrophic growth by (i) stabilizing the Mvh/Hdr/Fwd complex and (ii) activating formatedependent methanogenesis.

Methanobacterium aarhusense sp. nov., a novel methanogen isolated from a marine sediment (Aarhus Bay, Denmark).

PubMed

Shlimon, Adris Georgis; Friedrich, Michael W; Niemann, Helge; Ramsing, Niels Birger; Finster, Kai

2004-05-01

Strain H2-LR(T), a 5-18 micro m long and 0.7 micro m wide filamentous, mesophilic, moderately halophilic, non-motile hydrogenotrophic methanogen, was isolated from marine sediment of Aarhus Bay, Denmark, 1.7 m below the sediment surface. On the basis of 16S rRNA gene comparison with sequences of known methanogens, strain H2-LR(T) could be affiliated to the genus Methanobacterium. The strain forms a distinct line of descent within this genus, with Methanobacterium oryzae (95.9 % sequence identity) and Methanobacterium bryantii (95.7 % sequence identity) as its closest relatives. The 16S rRNA-based affiliation was supported by comparison of the mcrA gene, which encodes the alpha-subunit of methyl-coenzyme M reductase. Strain H2-LR(T) grew only on H(2)/CO(2). The DNA G+C content is 34.9 mol%. Optimum growth temperature was 45 degrees C. The strain grew equally well at pH 7.5 and 8. No growth or methane production was observed below pH 5 or above pH 9. Strain H2-LR(T) grew well within an NaCl concentration range of 100 and 900 mM. No growth or methane production was observed at 1 M NaCl. At 50 mM NaCl, growth and methane production were reduced. Based on 16S rRNA gene sequence analysis, the isolate is proposed to represent a novel taxon within the genus Methanobacterium, namely Methanobacterium aarhusense sp. nov. The type strain is H2-LR(T) (=DSM 15219(T)=ATCC BAA-828(T)).

Phospholipid Evidence for Methanogenic Archaea and Sulfate-reducing Bacteria in Coalbed Methane Wells in the Powder River Basin, Wyoming

NASA Astrophysics Data System (ADS)

Glossner, A.; Flores, R. M.; Mandernack, K.

2008-12-01

The Powder River Basin (PRB) comprises roughly 22,000 mi2 in northeastern Wyoming and southeastern Montana; it is a major source of coal and natural gas in the Rocky Mountain and Great Plains regions. The coalbed methane (CBM) produced from Paleocene Fort Union Formation coals in the PRB is thought primarily to be of bacterial origin due to its low δ13C values of -51 to -82 permil. Determination of the timing of methanogenesis, however, requires a methodology suitable for distinguishing viable methanogenic microorganisms. Here we provide evidence of living methanogenic Archaea and sulfate- reducing bacteria collected from co-produced water from CBM wells using phospholipid fatty acid (PLFA) and phospholipid ether lipid (PLEL) analyses. Twelve producing wells were sampled in May, 2007, using a high- pressure filtering apparatus. PLFAs were analyzed as fatty acid methyl esters and PLELs analyzed by their liberated core components using gas chromatography/mass spectrometry. Phospholipid analyses revealed an ecosystem dominated by Archaea, as the Archaeal isoprenoid, phytane, was the dominant phospholipid observed in nine of the wells sampled. Total microbial biomass estimates ranged from 1.1 ×106 cells/L to 8.3 ×107 cells/L, with the proportion of Archaeal cells ranging from 77.5 to 99.7 percent. In addition, the biomarkers 10me16:0, and cy17:0, considered to be biomarkers for genera of sulfate-reducing bacteria, were observed in several wells. The dominance of lipids from living Archaea in co- produced waters from CBM wells provides evidence supporting a recent origin of gas in the PRB coals.

The Cytosolic pH of Individual Saccharomyces cerevisiae Cells Is a Key Factor in Acetic Acid Tolerance.

PubMed

Fernández-Niño, Miguel; Marquina, Maribel; Swinnen, Steve; Rodríguez-Porrata, Boris; Nevoigt, Elke; Ariño, Joaquín

2015-11-01

It was shown recently that individual cells of an isogenic Saccharomyces cerevisiae population show variability in acetic acid tolerance, and this variability affects the quantitative manifestation of the trait at the population level. In the current study, we investigated whether cell-to-cell variability in acetic acid tolerance could be explained by the observed differences in the cytosolic pHs of individual cells immediately before exposure to the acid. Results obtained with cells of the strain CEN.PK113-7D in synthetic medium containing 96 mM acetic acid (pH 4.5) showed a direct correlation between the initial cytosolic pH and the cytosolic pH drop after exposure to the acid. Moreover, only cells with a low initial cytosolic pH, which experienced a less severe drop in cytosolic pH, were able to proliferate. A similar correlation between initial cytosolic pH and cytosolic pH drop was also observed in the more acid-tolerant strain MUCL 11987-9. Interestingly, a fraction of cells in the MUCL 11987-9 population showed initial cytosolic pH values below the minimal cytosolic pH detected in cells of the strain CEN.PK113-7D; consequently, these cells experienced less severe drops in cytosolic pH. Although this might explain in part the difference between the two strains with regard to the number of cells that resumed proliferation, it was observed that all cells from strain MUCL 11987-9 were able to proliferate, independently of their initial cytosolic pH. Therefore, other factors must also be involved in the greater ability of MUCL 11987-9 cells to endure strong drops in cytosolic pH. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

Comparison of the pattern, efficacy, and tolerability of self-medicated drugs in primary dysmenorrhea: a questionnaire based survey.

PubMed

Sugumar, Ramya; Krishnaiah, Vasundara; Channaveera, Gokul Shetty; Mruthyunjaya, Shilpa

2013-01-01

To compare the pattern, efficacy, and tolerability of self-medicated drugs and to assess the adequacy of their dose in primary dysmenorrhea (PD). A survey using a self-developed, validated, objective, and structured questionnaire as a tool was conducted among subjects with PD. Statistical analysis was carried out using Chi-square test and ANOVA with post-hoc Tuckey's test. Out of 641 respondents, 42% were self-medicated. The pattern of drugs used was: Dicyclomine, an unknown drug, mefenamic acid, mefenamic acid + dicyclomine, and metamizole by 35%, 29%, 26%, 9%, and 1% of respondents, respectively. Mefenamic acid + dicyclomine, the combination was the most efficacious in comparison to other drugs in moderate to severe dysmenorrhea. There was better tolerability with mefenamic acid + dicyclomine group compared to other drugs. Sub-therapeutic doses were used by 86% of self-medicating respondents. The prevailing self-medication practices were inappropriate in a substantial proportion of women with inadequate knowledge regarding appropriate drug choice, therapeutic doses, and their associated side effects.

A Prospective Examination of the Relations between Emotional Abuse and Anxiety: Moderation by Distress Tolerance

PubMed Central

Banducci, Anne N.; Lejuez, C.W.; Dougherty, Lea R.; MacPherson, Laura

2016-01-01

Objective Anxiety, the most common and impairing psychological problem experienced by youth, is associated with numerous individual and environmental factors. Two such factors include childhood emotional abuse (CEA) and low distress tolerance (DT). The current study aimed to understand how CEA and low DT impacted anxiety symptoms measured annually across five years among a community sample of youth. We hypothesized DT would moderate the relationship between CEA and anxiety, such that youth with higher levels of CEA and lower levels of DT would have elevated anxiety over time. Method Community youth (N = 244) were annually assessed across five years using the Revised Child Anxiety and Depression Scale, Childhood Trauma Questionnaire, and Behavioral Indicator of Resiliency to Distress. Results Higher CEA at baseline was associated with higher anxiety at baseline, higher anxiety at each annual assessment, and with greater overall decreases in anxiety over time. Lower DT was associated with higher anxiety at baseline, but did not predict changes in anxiety over time. Baseline DT significantly moderated the relationship between baseline CEA and anxiety, such that youth with both higher CEA and lower DT had the highest anxiety at each annual assessment. Conclusions Youth with lower DT and higher CEA scores had the highest level of anxiety symptoms across time. PMID:27501698

A Prospective Examination of the Relations Between Emotional Abuse and Anxiety: Moderation by Distress Tolerance.

PubMed

Banducci, Anne N; Lejuez, C W; Dougherty, Lea R; MacPherson, Laura

2017-01-01

Anxiety, the most common and impairing psychological problem experienced by youth, is associated with numerous individual and environmental factors. Two such factors include childhood emotional abuse (CEA) and low distress tolerance (DT). The current study aimed to understand how CEA and low DT impacted anxiety symptoms measured annually across 5 years among a community sample of youth. We hypothesized DT would moderate the relationship between CEA and anxiety, such that youth with higher levels of CEA and lower levels of DT would have elevated anxiety over time. Community youth (N = 244) were annually assessed across 5 years using the Revised Child Anxiety and Depression Scale, Childhood Trauma Questionnaire, and Behavioral Indicator of Resiliency to Distress. Higher CEA at baseline was associated with higher anxiety at baseline, higher anxiety at each annual assessment, and with greater overall decreases in anxiety over time. Lower DT was associated with higher anxiety at baseline, but did not predict changes in anxiety over time. Baseline DT significantly moderated the relationship between baseline CEA and anxiety, such that youth with both higher CEA and lower DT had the highest anxiety at each annual assessment. Youth with lower DT and higher CEA scores had the highest level of anxiety symptoms across time.

Production of polyunsaturated fatty acids in yeast Saccharomyces cerevisiae and its relation to alkaline pH tolerance.

PubMed

Yazawa, Hisashi; Iwahashi, Hitoshi; Kamisaka, Yasushi; Kimura, Kazuyoshi; Uemura, Hiroshi

2009-03-01

Saccharomyces cerevisiae produces saturated and monounsaturated fatty acids of 16- and 18-carbon atoms and no polyunsaturated fatty acids (PUFAs) with more than two double bonds. To study the biological significance of PUFAs in yeast, we introduced Kluyveromyces lactis Delta12 fatty acid desaturase (KlFAD2) and omega3 fatty acid desaturase (KlFAD3) genes into S. cerevisiae to produce linoleic and alpha-linolenic acids in S. cerevisiae. The strain producing linoleic and alpha-linolenic acids showed an alkaline pH-tolerant phenotype. DNA microarray analyses showed that the transcription of a set of genes whose expressions are under the repression of Rim101p were downregulated in this strain, suggesting that Rim101p, a transcriptional repressor which governs the ion tolerance, was activated. In line with this activation, the strain also showed elevated resistance to Li(+) and Na(+) ions and to zymolyase, a yeast lytic enzyme preparation containing mainly beta-1,3-glucanase, indicating that the cell wall integrity was also strengthened in this strain. Our findings demonstrate a novel influence of PUFA production on transcriptional control that is likely to play an important role in the early stage of alkaline stress response. The Accession No. for microarray data in the Center for Information Biology Gene Expression database is CBX68.

Gut Colonization by Methanogenic Archaea Is Associated with Organic Dairy Consumption in Children

PubMed Central

van de Pol, Jeroen A. A.; van Best, Niels; Mbakwa, Catherine A.; Thijs, Carel; Savelkoul, Paul H.; Arts, Ilja C. W.; Hornef, Mathias W.; Mommers, Monique; Penders, John

2017-01-01

The gut microbiota represents a complex and diverse ecosystem with a profound impact on human health, promoting immune maturation, and host metabolism as well as colonization resistance. Important members that have often been disregarded are the methanogenic archaea. Methanogenic archaea reduce hydrogen levels via the production of methane, thereby stimulating food fermentation by saccharolytic bacteria. On the other hand, colonization by archaea has been suggested to promote a number of gastrointestinal and metabolic diseases such as colorectal cancer, inflammatory bowel disease, and obesity. Archaea have been shown to be absent during infancy while omnipresent in school-aged children, suggesting that colonization may result from environmental exposure during childhood. The factors that determine the acquisition of methanogenic archaea, however, have remained undefined. Therefore, we aimed to explore determinants associated with the acquisition of the two main gastrointestinal archaeal species, Methanobrevibacter smithii and Methanosphaera stadtmanae, in children. Within the context of the KOALA Birth Cohort Study, fecal samples from 472 children aged 6–10 years were analyzed for the abundance of M. smithii and M. stadtmanae using qPCR. Environmental factors such as diet, lifestyle, hygiene, child rearing, and medication were recorded by repeated questionnaires. The relationship between these determinants and the presence and abundance of archaea was analyzed by logistic and linear regression respectively. Three hundred and sixty-nine out of the 472 children (78.2%) were colonized by M. smithii, and 39 out of the 472 children (8.3%) by M. stadtmanae. The consumption of organic yogurt (odds ratio: 4.25, CI95: 1.51; 11.95) and the consumption of organic milk (odds ratio: 5.58, CI95: 1.83; 17.01) were positively associated with the presence of M. smithii. We subsequently screened raw milk, processed milk, and yogurt samples for methanogens. We identified milk

Methanogenic pathway and community structure in a thermophilic anaerobic digestion process of organic solid waste.

PubMed

Sasaki, Daisuke; Hori, Tomoyuki; Haruta, Shin; Ueno, Yoshiyuki; Ishii, Masaharu; Igarashi, Yasuo

2011-01-01

The methanogenic pathway and microbial community in a thermophilic anaerobic digestion process of organic solid waste were investigated in a continuous-flow stirred-tank reactor using artificial garbage slurry as a feedstock. The decomposition pathway of acetate, a significant precursor of CH(4) and a key intermediate metabolite in the anaerobic digestion process, was analyzed by using stable isotopes. A tracer experiment using (13)C-labeled acetate revealed that approximately 80% of the acetate was decomposed via a non-aceticlastic oxidative pathway, whereas the remainder was converted to methane via an aceticlastic pathway. Archaeal 16S rRNA analyses demonstrated that the hydrogenotrophic methanogens Methanoculleus spp. accounted for >90% of detected methanogens, and the aceticlastic methanogens Methanosarcina spp. were the minor constituents. The clone library targeting bacterial 16S rRNA indicated the predominance of the novel Thermotogales bacterium (relative abundance: ~53%), which is related to anaerobic acetate oxidizer Thermotoga lettingae TMO, although the sequence similarity was low. Uncultured bacteria that phylogenetically belong to municipal solid waste cluster I were also predominant in the microflora (~30%). These results imply that the microbial community in the thermophilic degrading process of organic solid waste consists exclusively of unidentified bacteria, which efficiently remove acetate through a non-aceticlastic oxidative pathway. Copyright © 2010 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

DENTINE CARIES: ACID-TOLERANT MICROORGANISMS AND ASPECTS ON COLLAGEN DEGRADATION.

PubMed

Lager, Anders Hedenbjörk

2014-01-01

Dental caries is a common disease all over the world, despite the fact that it can be both effectively prevented and treated. It is driven by acids produced by oral microorganisms as a consequence of their metabolism of dietary carbohydrates. Given enough acid challenge, eventually the tooth enamel barrier will be broken down, and the carious lesion will extend into underlying hard tissue, forming a macroscopic cavity in the dentine. In comparison to biofilm on enamel, a dentine carious lesion provides a vastly different environment for the residing microorganisms. The environment influences the types and numbers of microorganisms that can colonize the dentine caries lesion. The overall aims for this thesis are to enumerate and further study microorganisms found in established dentine caries lesions and also to illuminate how host-derived proteolytic enzymes might contribute to this degradation, not only to better understand the caries process in dentine but also to find incitements for new methods to influence the natural progression of caries lesions. In Paper I, the numbers of remaining viable microorganisms after completed excavation using two excavation methods were investigated. Samples of carious dentine tissue were collected before and after excavation and cultivated on different agar media in different atmospheres. Analysis was performed by counting the number of colony-forming units (CFUs). Key findings: The number of remaining microorganisms after excavation was low for both methods, but some microorganisms always remained in the cavity floors even when the cavities were judged as caries free using normal clinical criteria. In Paper II, the acid tolerant microbiota in established dentine caries lesions was investigated. Samples were taken as in Paper I, but on three levels (superficial, center of lesion, floor of lesion after completed excavation). The samples were cultivated in anaerobic conditions on solid pH-selective agar media of different acidity

DNA microarray analysis of Methanosarcina mazei Gö1 reveals adaptation to different methanogenic substrates.

PubMed

Hovey, Raymond; Lentes, Sabine; Ehrenreich, Armin; Salmon, Kirsty; Saba, Karla; Gottschalk, Gerhard; Gunsalus, Robert P; Deppenmeier, Uwe

2005-05-01

Methansarcina mazei Gö1 DNA arrays were constructed and used to evaluate the genomic expression patterns of cells grown on either of two alternative methanogenic substrates, acetate or methanol, as sole carbon and energy source. Analysis of differential transcription across the genome revealed two functionally grouped sets of genes that parallel the central biochemical pathways in, and reflect many known features of, acetate and methanol metabolism. These include the acetate-induced genes encoding acetate activating enzymes, acetyl-CoA synthase/CO dehydrogenase, and carbonic anhydrase. Interestingly, additional genes expressed at significantly higher levels during growth on acetate included two energy-conserving complexes (the Ech hydrogenase, and the A1A0-type ATP synthase). Many previously unknown features included the induction by acetate of genes coding for ferredoxins and flavoproteins, an aldehyde:ferredoxin oxidoreductase, enzymes for the synthesis of aromatic amino acids, and components of iron, cobalt and oligopeptide uptake systems. In contrast, methanol-grown cells exhibited elevated expression of genes assigned to the methylotrophic pathway of methanogenesis. Expression of genes for components of the translation apparatus was also elevated in cells grown in the methanol medium relative to acetate, and was correlated with the faster growth rate observed on the former substrate. These experiments provide the first comprehensive insight into substrate-dependent gene expression in a methanogenic archaeon. This genome-wide approach, coupled with the complementary molecular and biochemical tools, should greatly accelerate the exploration of Methanosarcina cell physiology, given the present modest level of our knowledge of these large archaeal genomes.

Growth of Desulfovibrio in Lactate or Ethanol Media Low in Sulfate in Association with H2-Utilizing Methanogenic Bacteria

PubMed Central

Bryant, M. P.; Campbell, L. Leon; Reddy, C. A.; Crabill, M. R.

1977-01-01

In the analysis of an ethanol-CO2 enrichment of bacteria from an anaerobic sewage digestor, a strain tentatively identified as Desulfovibrio vulgaris and an H2-utilizing methanogen resembling Methanobacterium formicicum were isolated, and they were shown to represent a synergistic association of two bacterial species similar to that previously found between S organism and Methanobacterium strain MOH isolated from Methanobacillus omelianskii. In lowsulfate media, the desulfovibrio produced acetate and H2 from ethanol and acetate, H2, and, presumably, CO2 from lactate; but growth was slight and little of the energy source was catabolized unless the organism was combined with an H2-utilizing methanogenic bacterium. The type strains of D. vulgaris and Desulfovibrio desulfuricans carried out the same type of synergistic growth with methanogens. In mixtures of desulfovibrio and strain MOH growing on ethanol, lactate, or pyruvate, diminution of methane produced was stoichiometric with the moles of sulfate added, and the desulfovibrios grew better with sulfate addition. The energetics of the synergistic associations and of the competition between the methanogenic system and sulfate-reducing system as sinks for electrons generated in the oxidation of organic materials such as ethanol, lactate, and acetate are discussed. It is suggested that lack of availability of H2 for growth of methanogens is a major factor in suppression of methanogenesis by sulfate in natural ecosystems. The results with these known mixtures of bacteria suggest that hydrogenase-forming, sulfate-reducing bacteria could be active in some methanogenic ecosystems that are low in sulfate. PMID:879775

Growth of desulfovibrio in lactate or ethanol media low in sulfate in association with H2-utilizing methanogenic bacteria.

PubMed

Bryant, M P; Campbell, L L; Reddy, C A; Crabill, M R

1977-05-01

In the analysis of an ethanol-CO(2) enrichment of bacteria from an anaerobic sewage digestor, a strain tentatively identified as Desulfovibrio vulgaris and an H(2)-utilizing methanogen resembling Methanobacterium formicicum were isolated, and they were shown to represent a synergistic association of two bacterial species similar to that previously found between S organism and Methanobacterium strain MOH isolated from Methanobacillus omelianskii. In lowsulfate media, the desulfovibrio produced acetate and H(2) from ethanol and acetate, H(2), and, presumably, CO(2) from lactate; but growth was slight and little of the energy source was catabolized unless the organism was combined with an H(2)-utilizing methanogenic bacterium. The type strains of D. vulgaris and Desulfovibrio desulfuricans carried out the same type of synergistic growth with methanogens. In mixtures of desulfovibrio and strain MOH growing on ethanol, lactate, or pyruvate, diminution of methane produced was stoichiometric with the moles of sulfate added, and the desulfovibrios grew better with sulfate addition. The energetics of the synergistic associations and of the competition between the methanogenic system and sulfate-reducing system as sinks for electrons generated in the oxidation of organic materials such as ethanol, lactate, and acetate are discussed. It is suggested that lack of availability of H(2) for growth of methanogens is a major factor in suppression of methanogenesis by sulfate in natural ecosystems. The results with these known mixtures of bacteria suggest that hydrogenase-forming, sulfate-reducing bacteria could be active in some methanogenic ecosystems that are low in sulfate.

Uncoupling the Effects of Abscisic Acid on Plant Growth and Water Relations. Analysis of sto1/nced3, an Abscisic Acid-Deficient but Salt Stress-Tolerant Mutant in Arabidopsis1

PubMed Central

Ruggiero, Bruno; Koiwa, Hisashi; Manabe, Yuzuki; Quist, Tanya M.; Inan, Gunsu; Saccardo, Franco; Joly, Robert J.; Hasegawa, Paul M.; Bressan, Ray A.; Maggio, Albino

2004-01-01

We have identified a T-DNA insertion mutation of Arabidopsis (ecotype C24), named sto1 (salt tolerant), that results in enhanced germination on both ionic (NaCl) and nonionic (sorbitol) hyperosmotic media. sto1 plants were more tolerant in vitro than wild type to Na+ and K+ both for germination and subsequent growth but were hypersensitive to Li+. Postgermination growth of the sto1 plants on sorbitol was not improved. Analysis of the amino acid sequence revealed that STO1 encodes a 9-cis-epoxicarotenoid dioxygenase (similar to 9-cis-epoxicarotenoid dioxygenase GB:AAF26356 [Phaseolus vulgaris] and to NCED3 GB:AB020817 [Arabidopsis]), a key enzyme in the abscisic acid (ABA) biosynthetic pathway. STO1 transcript abundance was substantially reduced in mutant plants. Mutant sto1 plants were unable to accumulate ABA following a hyperosmotic stress, although their basal ABA level was only moderately altered. Either complementation of the sto1 with the native gene from the wild-type genome or supplementation of ABA to the growth medium restored the wild-type phenotype. Improved growth of sto1 mutant plants on NaCl, but not sorbitol, medium was associated with a reduction in both NaCl-induced expression of the ICK1 gene and ethylene accumulation. Osmotic adjustment of sto1 plants was substantially reduced compared to wild-type plants under conditions where sto1 plants grew faster. The sto1 mutation has revealed that reduced ABA can lead to more rapid growth during hyperionic stress by a signal pathway that apparently is at least partially independent of signals that mediate nonionic osmotic responses. PMID:15466233

Quantitative Proteomics Reveals the Flooding-Tolerance Mechanism in Mutant and Abscisic Acid-Treated Soybean.

PubMed

Yin, Xiaojian; Nishimura, Minoru; Hajika, Makita; Komatsu, Setsuko

2016-06-03

Flooding negatively affects the growth of soybean, and several flooding-specific stress responses have been identified; however, the mechanisms underlying flooding tolerance in soybean remain unclear. To explore the initial flooding tolerance mechanisms in soybean, flooding-tolerant mutant and abscisic acid (ABA)-treated plants were analyzed. In the mutant and ABA-treated soybeans, 146 proteins were commonly changed at the initial flooding stress. Among the identified proteins, protein synthesis-related proteins, including nascent polypeptide-associated complex and chaperonin 20, and RNA regulation-related proteins were increased in abundance both at protein and mRNA expression. However, these proteins identified at the initial flooding stress were not significantly changed during survival stages under continuous flooding. Cluster analysis indicated that glycolysis- and cell wall-related proteins, such as enolase and polygalacturonase inhibiting protein, were increased in abundance during survival stages. Furthermore, lignification of root tissue was improved even under flooding stress. Taken together, these results suggest that protein synthesis- and RNA regulation-related proteins play a key role in triggering tolerance to the initial flooding stress in soybean. Furthermore, the integrity of cell wall and balance of glycolysis might be important factors for promoting tolerance of soybean root to flooding stress during survival stages.

SEQUENTIAL REDUCTIVE DEHALOGATION OF CHLOROANILINES BY MICROORGANISMS FROM A METHANOGENIC AQUIFER

EPA Science Inventory

Chloroaniline-based compounds are widely used chem- icals and important contaminants of aquatic and terrestrial environments. We have found that chloroanilines can be biologically dehalogenated in polluted aquifers when methanogenic, but not sulfate-reducing conditions prevail. T...