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Sample records for bacterium myxococcus xanthus

  1. Cell Division Resets Polarity and Motility for the Bacterium Myxococcus xanthus

    PubMed Central

    Harvey, Cameron W.; Madukoma, Chinedu S.; Mahserejian, Shant; Alber, Mark S.

    2014-01-01

    Links between cell division and other cellular processes are poorly understood. It is difficult to simultaneously examine division and function in most cell types. Most of the research probing aspects of cell division has experimented with stationary or immobilized cells or distinctly asymmetrical cells. Here we took an alternative approach by examining cell division events within motile groups of cells growing on solid medium by time-lapse microscopy. A total of 558 cell divisions were identified among approximately 12,000 cells. We found an interconnection of division, motility, and polarity in the bacterium Myxococcus xanthus. For every division event, motile cells stop moving to divide. Progeny cells of binary fission subsequently move in opposing directions. This behavior involves M. xanthus Frz proteins that regulate M. xanthus motility reversals but is independent of type IV pilus “S motility.” The inheritance of opposing polarity is correlated with the distribution of the G protein RomR within these dividing cells. The constriction at the point of division limits the intracellular distribution of RomR. Thus, the asymmetric distribution of RomR at the parent cell poles becomes mirrored at new poles initiated at the site of division. PMID:25157084

  2. Tactic behavior of Myxococcus xanthus.

    PubMed Central

    Dworkin, M

    1983-01-01

    With time-lapse videomicroscopy it was demonstrated that cells of Myxococcus xanthus are capable of directed (tactic) movement toward appropriate targets. Mutants that had lost A motility (J. Hodgkin and D. Kaiser, Mol. Gen. Genet. 171:177-191, 1979) were unable to show directed movement. Cells showed directed movement to polystyrene latex beads and to glass beads, as well as to clumps of Micrococcus luteus. This is consistent with other observations in an accompanying paper (M. Dworkin and D. Eide, J. Bacteriol. 154:437-442, 1983) that indicate that M. xanthus does not perceive chemical gradients. Images PMID:6403511

  3. Active matter model of Myxococcus xanthus aggregation

    NASA Astrophysics Data System (ADS)

    Patch, Adam; Bahar, Fatmagul; Liu, Guannan; Thutupalli, Shashi; Welch, Roy; Yllanes, David; Shaevitz, Joshua; Marchetti, M. Cristina

    Myxococcus xanthus is a soil-dwelling bacterium that exhibits several fascinating collective behaviors including streaming, swarming, and generation of fruiting bodies. A striking feature of M. xanthus is that it periodically reverses its motility direction. The first stage of fruiting body formation is characterized by the aggregation of cells on a surface into round mesoscopic structures. Experiments have shown that this aggregation relies heavily on regulation of the reversal rate and local mechanical interactions, suggesting motility-induced phase separation may play an important role. We have adapted self-propelled particle models to include cell reversal and motility suppression resulting from sporulation observed in aggregates. Using 2D molecular dynamics simulations, we map the phase behavior in the space of Péclet number and local density and examine the kinetics of aggregation for comparison to experiments.

  4. Accordion waves in Myxococcus xanthus

    PubMed Central

    Sliusarenko, Oleksii; Neu, John; Zusman, David R.; Oster, George

    2006-01-01

    Myxococcus xanthus are Gram-negative bacteria that glide on solid surfaces, periodically reversing their direction of movement. When starved, M. xanthus cells organize their movements into waves of cell density that sweep over the colony surface. These waves are unique: Although they appear to interpenetrate, they actually reflect off one another when they collide, so that each wave crest oscillates back and forth with no net displacement. Because the waves reflect the coordinated back and forth oscillations of the individual bacteria, we call them “accordion” waves. The spatial oscillations of individuals are a manifestation of an internal biochemical oscillator, probably involving the Frz chemosensory system. These internal “clocks,” each of which is quite variable, are synchronized by collisions between individual cells using a contact-mediated signal-transduction system. The result of collision signaling is that the collective spatial behavior is much less variable than the individual oscillators. In this work, we present experimental observations in which individual cells marked with GFP can be followed in groups of unlabeled cells in monolayer cultures. These data, together with an agent-based computational model demonstrate that the only properties required to explain the ripple patterns are an asymmetric biochemical limit cycle that controls direction reversals and asymmetric contact-induced signaling between cells: Head-to-head signaling is stronger than head-to-tail signaling. Together, the experimental and computational data provide new insights into how populations of interacting oscillators can synchronize and organize spatially to produce morphogenetic patterns that may have parallels in higher organisms. PMID:16432222

  5. Crystal Structure of the HMG-CoA Synthase MvaS from the Gram-Negative Bacterium Myxococcus xanthus.

    PubMed

    Bock, Tobias; Kasten, Janin; Müller, Rolf; Blankenfeldt, Wulf

    2016-07-01

    A critical step in bacterial isoprenoid production is the synthesis of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) catalyzed by HMG-CoA synthase (HMGCS). In myxobacteria, this enzyme is also involved in a recently discovered alternative and acetyl-CoA-dependent isovaleryl CoA biosynthesis pathway. Here we present crystal structures of MvaS, the HMGCS from Myxococcus xanthus, in complex with CoA and acetylated active site Cys115, with the second substrate acetoacetyl CoA and with the product of the condensation reaction, 3-hydroxy-3-methylglutaryl CoA. With these structures, we show that MvaS uses the common HMGCS enzymatic mechanism and provide evidence that dimerization plays a role in the formation and stability of the active site. Overall, MvaS shows features typical of the eukaryotic HMGCS and exhibits differences from homologues from Gram-positive bacteria. This study provides insights into myxobacterial alternative isovaleryl CoA biosynthesis and thereby extends the toolbox for the biotechnological production of renewable fuel and chemicals. PMID:27124816

  6. Myxococcus xanthus Growth, Development, and Isolation.

    PubMed

    Vaksman, Zalman; Kaplan, Heidi B

    2015-01-01

    Myxobacteria are a highly social group among the delta proteobacteria that display unique multicellular behaviors during their complex life cycle and provide a rare opportunity to study the boundary between single cells and multicellularity. These organisms are also unusual as their entire life cycle is surface associated and includes a number of social behaviors: social gliding and rippling motility, 'wolf-pack'-like predation, and self-organizing complex biostructures, termed fruiting bodies, which are filled with differentiated environmentally resistant spores. Here we present methods for the growth, maintenance, and storage of Myxococcus xanthus, the most commonly studied of the myxobacteria. We also include methods to examine various developmental and social behaviors (fruiting body and spore formation, predation, and rippling motility). As the myxobacteria, similar to the streptomycetes, are excellent sources of many characterized and uncharacterized antibiotics and other natural products, we have provided a protocol for obtaining natural isolates from a variety of environmental sources. PMID:26528785

  7. Dual Biochemical Oscillators May Control Cellular Reversals in Myxococcus xanthus

    PubMed Central

    Eckhert, Erik; Rangamani, Padmini; Davis, Annie E.; Oster, George; Berleman, James E.

    2014-01-01

    Myxococcus xanthus is a Gram-negative, soil-dwelling bacterium that glides on surfaces, reversing direction approximately once every 6 min. Motility in M. xanthus is governed by the Che-like Frz pathway and the Ras-like Mgl pathway, which together cause the cell to oscillate back and forth. Previously, Igoshin et al. (2004) suggested that the cellular oscillations are caused by cyclic changes in concentration of active Frz proteins that govern motility. In this study, we present a computational model that integrates both the Frz and Mgl pathways, and whose downstream components can be read as motor activity governing cellular reversals. This model faithfully reproduces wildtype and mutant behaviors by simulating individual protein knockouts. In addition, the model can be used to examine the impact of contact stimuli on cellular reversals. The basic model construction relies on the presence of two nested feedback circuits, which prompted us to reexamine the behavior of M. xanthus cells. We performed experiments to test the model, and this cell analysis challenges previous assumptions of 30 to 60 min reversal periods in frzCD, frzF, frzE, and frzZ mutants. We demonstrate that this average reversal period is an artifact of the method employed to record reversal data, and that in the absence of signal from the Frz pathway, Mgl components can occasionally reverse the cell near wildtype periodicity, but frz- cells are otherwise in a long nonoscillating state. PMID:25468349

  8. Earthquake-like dynamics in Myxococcus xanthus social motility

    PubMed Central

    Gibiansky, Maxsim L.; Hu, Wei; Dahmen, Karin A.; Shi, Wenyuan; Wong, Gerard C. L.

    2013-01-01

    Myxococcus xanthus is a bacterium capable of complex social organization. Its characteristic social (“S”)-motility mechanism is mediated by type IV pili (TFP), linear actuator appendages that propel the bacterium along a surface. TFP are known to bind to secreted exopolysaccharides (EPS), but it is unclear how M. xanthus manages to use the TFP-EPS technology common to many bacteria to achieve its unique coordinated multicellular movements. We examine M. xanthus S-motility, using high-resolution particle-tracking algorithms, and observe aperiodic stick–slip movements. We show that they are not due to chemotaxis, but are instead consistent with a constant TFP-generated force interacting with EPS, which functions both as a glue and as a lubricant. These movements are quantitatively homologous to the dynamics of earthquakes and other crackling noise systems. These systems exhibit critical behavior, which is characterized by a statistical hierarchy of discrete “avalanche” motions described by a power law distribution. The measured critical exponents from M. xanthus are consistent with mean field theoretical models and with other crackling noise systems, and the measured Lyapunov exponent suggests the existence of highly branched EPS. Such molecular architectures, which are common for efficient lubricants but rare in bacterial EPS, may be necessary for S-motility: We show that the TFP of leading “locomotive” cells initiate the collective motion of follower cells, indicating that lubricating EPS may alleviate the force generation requirements on the lead cell and thus make S-motility possible. PMID:23341622

  9. Regulated Exopolysaccharide Production in Myxococcus xanthus

    PubMed Central

    Kim, Sang-Hoon; Ramaswamy, Srinivas; Downard, John

    1999-01-01

    Myxococcus xanthus fibrils are cell surface-associated structures composed of roughly equal amounts of polysaccharide and protein. The level of M. xanthus polysaccharide production under different conditions in the wild type and in several mutants known to have alterations in fibril production was investigated. Wild-type exopolysaccharide increased significantly as cells entered the stationary phase of growth or upon addition of Ca2+ to growing cells, and the polysaccharide-induced cells exhibited an enhanced capacity for cell-cell agglutination. The activity of the key gluconeogenic pathway enzyme phosphoenolpyruvate carboxykinase (Pck) also increased under these conditions. Most fibril-deficient mutants failed to produce polysaccharide in a stationary-phase- or Ca2+-dependent fashion. However, regulation of Pck activity was generally unimpaired in these mutant strains. In an stk mutant, which overproduces fibrils, polysaccharide production and Pck activity were constitutively high under the conditions tested. Polysaccharide production increased in most fibril-deficient strains when an stk mutant allele was present, indicating that these fibril-deficient mutants retained the basic cellular components required for fibril polysaccharide production. In contrast to other divalent cations tested, Sr2+ effectively replaced Ca2+ in stimulating polysaccharide production, and either Ca2+ or Sr2+ was required for fruiting-body formation by wild-type cells. By using transmission electron microscopy of freeze-substituted log-phase wild-type cells, fibril material was observed as a cell surface-associated layer of uniform thickness composed of filaments with an ordered structure. PMID:10049381

  10. Gliding Motility in Bacteria: Insights from Studies of Myxococcus xanthus

    PubMed Central

    Spormann, Alfred M.

    1999-01-01

    Gliding motility is observed in a large variety of phylogenetically unrelated bacteria. Gliding provides a means for microbes to travel in environments with a low water content, such as might be found in biofilms, microbial mats, and soil. Gliding is defined as the movement of a cell on a surface in the direction of the long axis of the cell. Because this definition is operational and not mechanistic, the underlying molecular motor(s) may be quite different in diverse microbes. In fact, studies on the gliding bacterium Myxococcus xanthus suggest that two independent gliding machineries, encoded by two multigene systems, operate in this microorganism. One machinery, which allows individual cells to glide on a surface, independent of whether the cells are moving alone or in groups, requires the function of the genes of the A-motility system. More than 37 A-motility genes are known to be required for this form of movement. Depending on an additional phenotype, these genes are divided into two subclasses, the agl and cgl genes. Videomicroscopic studies on gliding movement, as well as ultrastructural observations of two myxobacteria, suggest that the A-system motor may consist of multiple single motor elements that are arrayed along the entire cell body. Each motor element is proposed to be localized to the periplasmic space and to be anchored to the peptidoglycan layer. The force to glide which may be generated here is coupled to adhesion sites that move freely in the outer membrane. These adhesion sites provide a specific contact with the substratum. Based on single-cell observations, similar models have been proposed to operate in the unrelated gliding bacteria Flavobacterium johnsoniae (formerly Cytophaga johnsonae), Cytophaga strain U67, and Flexibacter polymorphus (a filamentous glider). Although this model has not been verified experimentally, M. xanthus seems to be the ideal organism with which to test it, given the genetic tools available. The second gliding

  11. The high-mobility group A-type protein CarD of the bacterium Myxococcus xanthus as a transcription factor for several distinct vegetative genes.

    PubMed Central

    Galbis-Martínez, Marisa; Fontes, Marta; Murillo, Francisco J

    2004-01-01

    CarD is the only reported prokaryotic protein showing structural and functional features typical of eukaryotic high-mobility group A transcription factors. In prokaryotes, proteins similar to CarD appear to be confined primarily to myxobacteria. In Myxococcus xanthus, CarD has been previously shown to act as a positive element in two different regulatory networks: one for light-induced synthesis of carotenoids and the other for starvation-induced fruiting body formation. We have now tested the effect of a loss-of-function mutation in the carD gene (carD1) on the expression of a random collection of lacZ-tagged genes, which are normally expressed in the dark during vegetative growth in rich medium. Our results indicate that CarD plays a significant role in the transcriptional regulation of various indicated genes. The carD1 mutation downregulates some genes and upregulates others. Also reported here is the isolation of several mutations that suppress the strong effect of carD1 on the expression of a particular vegetative gene. One of them (sud-2) also suppresses the effect of carD1 on other vegetative genes and on fruiting-body formation. Thus, CarD and the sud-2 gene product appear to participate in a single mechanism, which underlies various apparently diverse regulatory phenomena ascribed to CarD. PMID:15342500

  12. Pattern-formation mechanisms in motility mutants of Myxococcus xanthus

    PubMed Central

    Starruß, Jörn; Peruani, Fernando; Jakovljevic, Vladimir; Søgaard-Andersen, Lotte; Deutsch, Andreas; Bär, Markus

    2012-01-01

    Formation of spatial patterns of cells is a recurring theme in biology and often depends on regulated cell motility. Motility of the rod-shaped cells of the bacterium Myxococcus xanthus depends on two motility machineries, type IV pili (giving rise to S-motility) and the gliding motility apparatus (giving rise to A-motility). Cell motility is regulated by occasional reversals. Moving M. xanthus cells can organize into spreading colonies or spore-filled fruiting bodies, depending on their nutritional status. To ultimately understand these two pattern-formation processes and the contributions by the two motility machineries, as well as the cell reversal machinery, we analyse spatial self-organization in three M. xanthus strains: (i) a mutant that moves unidirectionally without reversing by the A-motility system only, (ii) a unidirectional mutant that is also equipped with the S-motility system, and (iii) the wild-type that, in addition to the two motility systems, occasionally reverses its direction of movement. The mutant moving by means of the A-engine illustrates that collective motion in the form of large moving clusters can arise in gliding bacteria owing to steric interactions of the rod-shaped cells, without the need of invoking any biochemical signal regulation. The two-engine strain mutant reveals that the same phenomenon emerges when both motility systems are present, and as long as cells exhibit unidirectional motion only. From the study of these two strains, we conclude that unidirectional cell motion induces the formation of large moving clusters at low and intermediate densities, while it results in vortex formation at very high densities. These findings are consistent with what is known from self-propelled rod models, which strongly suggests that the combined effect of self-propulsion and volume exclusion interactions is the pattern-formation mechanism leading to the observed phenomena. On the other hand, we learn that when cells occasionally reverse

  13. Stigmergy co-ordinates multicellular collective behaviours during Myxococcus xanthus surface migration.

    PubMed

    Gloag, Erin S; Turnbull, Lynne; Javed, Muhammad A; Wang, Huabin; Gee, Michelle L; Wade, Scott A; Whitchurch, Cynthia B

    2016-01-01

    Surface translocation by the soil bacterium Myxococcus xanthus is a complex multicellular phenomenon that entails two motility systems. However, the mechanisms by which the activities of individual cells are coordinated to manifest this collective behaviour are currently unclear. Here we have developed a novel assay that enables detailed microscopic examination of M. xanthus motility at the interstitial interface between solidified nutrient medium and a glass coverslip. Under these conditions, M. xanthus motility is characterised by extensive micro-morphological patterning that is considerably more elaborate than occurs at an air-surface interface. We have found that during motility on solidified nutrient medium, M. xanthus forges an interconnected furrow network that is lined with an extracellular matrix comprised of exopolysaccharides, extracellular lipids, membrane vesicles and an unidentified slime. Our observations have revealed that M. xanthus motility on solidified nutrient medium is a stigmergic phenomenon in which multi-cellular collective behaviours are co-ordinated through trail-following that is guided by physical furrows and extracellular matrix materials. PMID:27225967

  14. Stigmergy co-ordinates multicellular collective behaviours during Myxococcus xanthus surface migration

    PubMed Central

    Gloag, Erin S.; Turnbull, Lynne; Javed, Muhammad A.; Wang, Huabin; Gee, Michelle L.; Wade, Scott A.; Whitchurch, Cynthia B.

    2016-01-01

    Surface translocation by the soil bacterium Myxococcus xanthus is a complex multicellular phenomenon that entails two motility systems. However, the mechanisms by which the activities of individual cells are coordinated to manifest this collective behaviour are currently unclear. Here we have developed a novel assay that enables detailed microscopic examination of M. xanthus motility at the interstitial interface between solidified nutrient medium and a glass coverslip. Under these conditions, M. xanthus motility is characterised by extensive micro-morphological patterning that is considerably more elaborate than occurs at an air-surface interface. We have found that during motility on solidified nutrient medium, M. xanthus forges an interconnected furrow network that is lined with an extracellular matrix comprised of exopolysaccharides, extracellular lipids, membrane vesicles and an unidentified slime. Our observations have revealed that M. xanthus motility on solidified nutrient medium is a stigmergic phenomenon in which multi-cellular collective behaviours are co-ordinated through trail-following that is guided by physical furrows and extracellular matrix materials. PMID:27225967

  15. Cell Alignment Required in Differentiation of Myxococcus xanthus

    NASA Astrophysics Data System (ADS)

    Kim, Seung K.; Kaiser, Dale

    1990-08-01

    During fruiting body morphogenesis of Myxococcus xanthus, cell movement is required for transmission of C-factor, a short range intercellular signaling protein necessary for sporulation and developmental gene expression. Nonmotile cells fail to sporulate and to express C-factor-dependent genes, but both defects were rescued by a simple manipulation of cell position that oriented the cells in aligned, parallel groups. A similar pattern of aligned cells normally results from coordinated recruitment of wild-type cells into multicellular aggregates, which later form mature fruiting bodies. It is proposed that directed cell movement establishes critical contacts between adjacent cells, which are required for efficient intercellular C-factor transmission.

  16. The lethal cargo of Myxococcus xanthus outer membrane vesicles

    PubMed Central

    Berleman, James E.; Allen, Simon; Danielewicz, Megan A.; Remis, Jonathan P.; Gorur, Amita; Cunha, Jack; Hadi, Masood Z.; Zusman, David R.; Northen, Trent R.; Witkowska, H. Ewa; Auer, Manfred

    2014-01-01

    Myxococcus xanthus is a bacterial micro-predator known for hunting other microbes in a wolf pack-like manner. Outer membrane vesicles (OMVs) are produced in large quantities by M. xanthus and have a highly organized structure in the extracellular milieu, sometimes occurring in chains that link neighboring cells within a biofilm. OMVs may be a vehicle for mediating wolf pack activity by delivering hydrolytic enzymes and antibiotics aimed at killing prey microbes. Here, both the protein and small molecule cargo of the OMV and membrane fractions of M. xanthus were characterized and compared. Our analysis indicates a number of proteins that are OMV-specific or OMV-enriched, including several with putative hydrolytic function. Secondary metabolite profiling of OMVs identifies 16 molecules, many associated with antibiotic activities. Several hydrolytic enzyme homologs were identified, including the protein encoded by MXAN_3564 (mepA), an M36 protease homolog. Genetic disruption of mepA leads to a significant reduction in extracellular protease activity suggesting MepA is part of the long-predicted (yet to date undetermined) extracellular protease suite of M. xanthus. PMID:25250022

  17. Mechanism for Collective Cell Alignment in Myxococcus xanthus Bacteria

    PubMed Central

    Balagam, Rajesh; Igoshin, Oleg A.

    2015-01-01

    Myxococcus xanthus cells self-organize into aligned groups, clusters, at various stages of their lifecycle. Formation of these clusters is crucial for the complex dynamic multi-cellular behavior of these bacteria. However, the mechanism underlying the cell alignment and clustering is not fully understood. Motivated by studies of clustering in self-propelled rods, we hypothesized that M. xanthus cells can align and form clusters through pure mechanical interactions among cells and between cells and substrate. We test this hypothesis using an agent-based simulation framework in which each agent is based on the biophysical model of an individual M. xanthus cell. We show that model agents, under realistic cell flexibility values, can align and form cell clusters but only when periodic reversals of cell directions are suppressed. However, by extending our model to introduce the observed ability of cells to deposit and follow slime trails, we show that effective trail-following leads to clusters in reversing cells. Furthermore, we conclude that mechanical cell alignment combined with slime-trail-following is sufficient to explain the distinct clustering behaviors observed for wild-type and non-reversing M. xanthus mutants in recent experiments. Our results are robust to variation in model parameters, match the experimentally observed trends and can be applied to understand surface motility patterns of other bacterial species. PMID:26308508

  18. Mechanism of cell alignment in groups of Myxococcus xanthus bacteria

    NASA Astrophysics Data System (ADS)

    Balgam, Rajesh; Igoshin, Oleg

    2015-03-01

    Myxococcus xanthus is a model for studying self-organization in bacteria. These flexible cylindrical bacteria move along. In groups, M. xanthus cells align themselves into dynamic cell clusters but the mechanism underlying their formation is unknown. It has been shown that steric interactions can cause alignment in self-propelled hard rods but it is not clear how flexibility and reversals affect the alignment and cluster formation. We have investigated cell alignment process using our biophysical model of M. xanthus cell in an agent-based simulation framework under realistic cell flexibility values. We observed that flexible model cells can form aligned cell clusters when reversals are suppressed but these clusters disappeared when reversals frequency becomes similar to the observed value. However, M. xanthus cells follow slime (polysaccharide gel like material) trails left by other cells and we show that implementing this into our model rescues cell clustering for reversing cells. Our results show that slime following along with periodic cell reversals act as positive feedback to reinforce existing slime trails and recruit more cells. Furthermore, we have observed that mechanical cell alignment combined with slime following is sufficient to explain the distinct clustering patterns of reversing and non-reversing cells as observed in recent experiments. This work is supported by NSF MCB 0845919 and 1411780.

  19. Mechanism for Collective Cell Alignment in Myxococcus xanthus Bacteria.

    PubMed

    Balagam, Rajesh; Igoshin, Oleg A

    2015-08-01

    Myxococcus xanthus cells self-organize into aligned groups, clusters, at various stages of their lifecycle. Formation of these clusters is crucial for the complex dynamic multi-cellular behavior of these bacteria. However, the mechanism underlying the cell alignment and clustering is not fully understood. Motivated by studies of clustering in self-propelled rods, we hypothesized that M. xanthus cells can align and form clusters through pure mechanical interactions among cells and between cells and substrate. We test this hypothesis using an agent-based simulation framework in which each agent is based on the biophysical model of an individual M. xanthus cell. We show that model agents, under realistic cell flexibility values, can align and form cell clusters but only when periodic reversals of cell directions are suppressed. However, by extending our model to introduce the observed ability of cells to deposit and follow slime trails, we show that effective trail-following leads to clusters in reversing cells. Furthermore, we conclude that mechanical cell alignment combined with slime-trail-following is sufficient to explain the distinct clustering behaviors observed for wild-type and non-reversing M. xanthus mutants in recent experiments. Our results are robust to variation in model parameters, match the experimentally observed trends and can be applied to understand surface motility patterns of other bacterial species. PMID:26308508

  20. Rhizobial galactoglucan determines the predatory pattern of Myxococcus xanthus and protects Sinorhizobium meliloti from predation

    PubMed Central

    Pérez, Juana; Jiménez-Zurdo, José I.; Martínez-Abarca, Francisco; Millán, Vicenta; Shimkets, Lawrence J.; Muñoz-Dorado, José

    2014-01-01

    Summary Myxococcus xanthus is a social bacterium that preys on prokaryotic and eukaryotic microorganisms. Co-culture of M. xanthus with reference laboratory strains and field isolates of the legume symbiont Sinorhizobium meliloti revealed two different predatory patterns that resemble frontal and wolfpack attacks. Use of mutants impaired in the two types of M. xanthus surface motility (A or adventurous and S or social motility) and a csgA mutant, which is unable to form macroscopic travelling waves known as ripples, has demonstrated that both motility systems but not rippling are required for efficient predation. To avoid frontal attack and reduce killing rates, rhizobial cells require a functional expR gene. ExpR regulates expression of genes involved in a variety of functions. The use of S. meliloti mutants impaired in several of these functions revealed that the exopolysaccharide galactoglucan (EPS II) is the major determinant of the M. xanthus predatory pattern. The data also suggest that this biopolymer confers an ecological advantage to rhizobial survival in soil, which may have broad environmental implications. PMID:24707988

  1. Identification and characterization of five cspA homologous genes from Myxococcus xanthus.

    PubMed

    Yamanaka, K; Inouye, M; Inouye, S

    1999-10-28

    Escherichia coli contains a large CspA family consisting of nine homologues, in which four are cold-shock inducible and one is stationary-phase inducible. Here, we demonstrate that Myxococcus xanthus possesses at least five CspA homologues, CspA to CspE. Hydrophobic residues forming a hydrophobic core, and aromatic residues, which are included in functional motifs RNP-1 and RNP-2 involved in binding to RNA and ssDNA, are well conserved. These facts suggest that M. xanthus CspA homologues have a similar structure and function as E. coli CspA. However, in contrast to the E. coli CspA family, the expression of M. xanthus csp genes as judged by primer extension analysis is not significantly regulated by temperature changes, except for cspB of which expression was reduced to less than 10% upon heat shock at 42 degrees C. Such constitutive expression of the csp genes may be important for M. xanthus, a soil-dwelling bacterium, to survive under conditions of exposure to various environmental changes in nature. PMID:10542339

  2. Predation by Myxococcus xanthus induces Bacillus subtilis to form spore-filled megastructures.

    PubMed

    Müller, Susanne; Strack, Sarah N; Ryan, Sarah E; Kearns, Daniel B; Kirby, John R

    2015-01-01

    Biofilm formation is a common mechanism for surviving environmental stress and can be triggered by both intraspecies and interspecies interactions. Prolonged predator-prey interactions between the soil bacterium Myxococcus xanthus and Bacillus subtilis were found to induce the formation of a new type of B. subtilis biofilm, termed megastructures. Megastructures are tree-like brachiations that are as large as 500 μm in diameter, are raised above the surface between 150 and 200 μm, and are filled with viable endospores embedded within a dense matrix. Megastructure formation did not depend on TasA, EpsE, SinI, RemA, or surfactin production and thus is genetically distinguishable from colony biofilm formation on MSgg medium. As B. subtilis endospores are not susceptible to predation by M. xanthus, megastructures appear to provide an alternative mechanism for survival. In addition, M. xanthus fruiting bodies were found immediately adjacent to the megastructures in nearly all instances, suggesting that M. xanthus is unable to acquire sufficient nutrients from cells housed within the megastructures. Lastly, a B. subtilis mutant lacking the ability to defend itself via bacillaene production formed megastructures more rapidly than the parent. Together, the results indicate that production of the megastructure facilitates B. subtilis escape into dormancy via sporulation. PMID:25326308

  3. Growth of Myxococcus xanthus in Continuous-Flow-Cell Bioreactors as a Method for Studying Development

    PubMed Central

    Smaldone, Gregory T.; Jin, Yujie; Whitfield, Damion L.; Mu, Andrew Y.; Wong, Edward C.; Wuertz, Stefan

    2014-01-01

    Nutrient sensors and developmental timers are two classes of genes vital to the establishment of early development in the social soil bacterium Myxococcus xanthus. The products of these genes trigger and regulate the earliest events that drive the colony from a vegetative state to aggregates, which ultimately leads to the formation of fruiting bodies and the cellular differentiation of the individual cells. In order to more accurately identify the genes and pathways involved in the initiation of this multicellular developmental program in M. xanthus, we adapted a method of growing vegetative populations within a constant controllable environment by using flow cell bioreactors, or flow cells. By establishing an M. xanthus community within a flow cell, we are able to test developmental responses to changes in the environment with fewer concerns for effects due to nutrient depletion or bacterial waste production. This approach allows for greater sensitivity in investigating communal environmental responses, such as nutrient sensing. To demonstrate the versatility of our growth environment, we carried out time-lapse confocal laser scanning microscopy to visualize M. xanthus biofilm growth and fruiting body development, as well as fluorescence staining of exopolysaccharides deposited by biofilms. We also employed the flow cells in a nutrient titration to determine the minimum concentration required to sustain vegetative growth. Our data show that by using a flow cell, M. xanthus can be held in a vegetative growth state at low nutrient concentrations for long periods, and then, by slightly decreasing the nutrient concentration, cells can be allowed to initiate the developmental program. PMID:24509931

  4. A CRISPR with Roles in Myxococcus xanthus Development and Exopolysaccharide Production

    PubMed Central

    Wallace, Regina A.; Black, Wesley P.; Yang, Xianshuang

    2014-01-01

    The Gram-negative soil bacterium Myxococcus xanthus utilizes its social (S) gliding motility to move on surfaces during its vegetative and developmental cycles. It is known that S motility requires the type IV pilus (T4P) and the exopolysaccharide (EPS) to function. The T4P is the S motility motor, and it powers cell movement by retraction. As the key regulator of the S motor, EPS is proposed to be the anchor and trigger for T4P retraction. The production of EPS is regulated in turn by the T4P in M. xanthus, and T4P− mutants are S− and EPS−. In this study, a ΔpilA strain (T4P− and EPS−) was mutagenized by a transposon and screened for EPS+ mutants. A pilA suppressor isolated as such harbored an insertion in the 3rd clustered regularly interspaced short palindromic repeat (CRISPR3) in M. xanthus. Evidence indicates that this transposon insertion, designated CRISPR3*, is a gain-of-function (GOF) mutation. Moreover, CRISPR3* eliminated developmental aggregation in both the wild-type and the pilA mutant backgrounds. Upstream of CRISPR3 are genes encoding the repeat-associated mysterious proteins (RAMPs). These RAMP genes are indispensable for CRISPR3* to affect development and EPS in M. xanthus. Analysis by reverse transcription (RT)-PCR suggested that CRISPR3* led to an increase in the processing of the RNA transcribed from CRISPR3. We propose that certain CRISPR3 transcripts, once expressed and processed, target genes critical for M. xanthus fruiting body development and EPS production in a RAMP-dependent manner. PMID:25201946

  5. Coats from Myxococcus xanthus: characterization and synthesis during myxospore differentiation.

    PubMed

    Kottel, R H; Bacon, K; Clutter, D; White, D

    1975-10-01

    An extracellular coat from glycerol-induced myxospores of Myxococcus xanthus has been isolated and characterized. Coats were examined chemically and by using both transmission and scanning electron microscopy. On a dry weight basis, approximately 75% of the coat is polysaccharide composed entirely of galactosamine and glucose. The remainder of the coat is protein (14%), glycine (8%), and organic phosphorus (less than 1%). Coats remained morphologically intact despite boiling in 10 M urea, sodium lauryl sulfate plus beta-mercaptoethanol, or extraction with warm phenol. Coats also resisted digestion with a variety of proteolytic and polysaccharide degrading enzymes. Synthesis of myxospore coat begins approximately 1 h after the addition of glycerol to a culture. One portion of the coat is complete by 5 to 6 h but additional material consisting primarily of glucose is added after 8 h. PMID:809426

  6. Methylation of macromolecules during development in Myxococcus xanthus.

    PubMed Central

    Panasenko, S M

    1985-01-01

    Covalent modification of macromolecules can serve to alter their biological activities and is therefore frequently involved in regulation. I examined methylation of proteins and carbohydrates during development and vegetative growth in the procaryote Myxococcus xanthus. Striking differences in the patterns of protein methylation occurred when cell development was induced by nutrient deprivation on solid media and when cells were starved in liquid. In addition, a methylated, protease-resistant macromolecule which contained carbohydrate and which may have been an unusual type of lipopolysaccharide was observed on sodium dodecyl sulfate-polyacrylamide gels. A comparison of methylation patterns in various media and an analysis of the time course of methylation indicated that changes in methylation were part of the developmental pathway which includes aggregation. Induction of development in liquid by glycerol produced no changes in methylation. Images PMID:3932324

  7. Bacterial Social Networks: Structure and composition of Myxococcus xanthus outer membrane vesicle chains

    PubMed Central

    Remis, Jonathan P.; Wei, Doug; Gorur, Amita; Zemla, Marcin; Haraga, Jessica; Allen, Simon; Witkowska, H. Ewa; Costerton, J. William; Berleman, James E.; Auer, Manfred

    2014-01-01

    Summary The social soil bacterium, Myxococcus xanthus, displays a variety of complex and highly coordinated behaviors, including social motility, predatory rippling and fruiting body formation. Here we show that M. xanthus cells produce a network of outer membrane extensions in the form of vesicles and vesicle chains that interconnect cells. We observed peritrichous display of vesicles and vesicle chains and increased abundance in biofilms compared to planktonic cultures. By applying a range of imaging techniques, including 3D Focused Ion Beam Scanning Electron Microscopy (FIB/SEM), we determined these structures to range between 30-60 nm in width and up to 5 μm in length. Purified vesicle chains consist of typical M. xanthus lipids, fucose, mannose, N-acetylglucosamine (GlcNAc) and N-acetylgalactoseamine (GalNAc) carbohydrates and a small set of cargo protein. The protein content includes CglB and Tgl membrane proteins transferred in a contact-dependent manner. Most significantly, the 3D organization of cells within biofilms indicates that cells are connected via an extensive network of membrane extensions that may connect cells at the level of the periplasmic space. Such a network would allow the transfer of membrane proteins and other molecules between cells, and likely provides a mechanism for the coordination of social activities. PMID:23848955

  8. Study of elastic collisions of Myxococcus xanthus in swarms

    NASA Astrophysics Data System (ADS)

    Harvey, Cameron W.; Morcos, Faruck; Sweet, Christopher R.; Kaiser, Dale; Chatterjee, Santanu; Liu, Xiaomin; Chen, Danny Z.; Alber, Mark

    2011-04-01

    In very low density situations where a single myxobacterial cell is isolated from direct contact with other cells, the slime capsule interaction with the substrate or slime tracks on the substrate produce a viscous drag that results in a smooth gliding motion. Viscoelastic interactions of myxobacteria cells in a low-density domain close to the edge of a swarm are studied using a combination of a cell-based three-dimensional computational model and cell-tracking experiments. The model takes into account the flexible nature of Myxococcus xanthus as well as the effects of adhesion between cells arising from the interaction of the capsular polysaccharide covering two cells in contact with each other. New image and dynamic cell curvature analysis algorithms are used to track and measure the change in cell shapes that occur as flexible cells undergo significant bending during collisions resulting in direct calibration of the model parameters. Like aspect-ratio and directional reversals, the flexibility of cells and the adhesive cell-cell and cell-substrate interactions of M. xanthus play an important role in smooth gliding and more efficient swarming.

  9. Beta-D-Allose inhibits fruiting body formation and sporulation in Myxococcus xanthus.

    PubMed

    Chavira, Marielena; Cao, Nga; Le, Karen; Riar, Tanveer; Moradshahi, Navid; McBride, Melinda; Lux, Renate; Shi, Wenyuan

    2007-01-01

    Myxococcus xanthus, a gram-negative soil bacterium, responds to amino acid starvation by entering a process of multicellular development which culminates in the assembly of spore-filled fruiting bodies. Previous studies utilizing developmental inhibitors (such as methionine, lysine, or threonine) have revealed important clues about the mechanisms involved in fruiting body formation. We used Biolog phenotype microarrays to screen 384 chemicals for complete inhibition of fruiting body development in M. xanthus. Here, we report the identification of a novel inhibitor of fruiting body formation and sporulation, beta-d-allose. beta-d-Allose, a rare sugar, is a member of the aldohexose family and a C3 epimer of glucose. Our studies show that beta-d-allose does not affect cell growth, viability, agglutination, or motility. However, beta-galactosidase reporters demonstrate that genes activated between 4 and 14 h of development show significantly lower expression levels in the presence of beta-d-allose. Furthermore, inhibition of fruiting body formation occurs only when beta-d-allose is added to submerged cultures before 12 h of development. In competition studies, high concentrations of galactose and xylose antagonize the nonfruiting response to beta-d-allose, while glucose is capable of partial antagonism. Finally, a magellan-4 transposon mutagenesis screen identified glcK, a putative glucokinase gene, required for beta-d-allose-mediated inhibition of fruiting body formation. Subsequent glucokinase activity assays of the glcK mutant further supported the role of this protein in glucose phosphorylation. PMID:17056749

  10. Effect of cellular filamentation on adventurous and social gliding motility of Myxococcus xanthus

    PubMed Central

    Sun, Hong; Yang, Zhaomin; Shi, Wenyuan

    1999-01-01

    Filamentous bacterial cells often provide biological information that is not readily evident in normal-size cells. In this study, the effect of cellular filamentation on gliding motility of Myxococcus xanthus, a Gram-negative social bacterium, was investigated. Elongation of the cell body had different effects on adventurous and social motility of M. xanthus. The rate of A-motility was insensitive to cell-body elongation whereas the rate of S-motility was reduced dramatically as the cell body got longer, indicating that these two motility systems work in different ways. The study also showed that filamentous wild-type cells glide smoothly with relatively straight, long cell bodies. However, filamentous cells of certain social motility mutants showed zigzag, tangled cell bodies on a solid surface, apparently a result of a lack of coordination between different fragments within the filaments. Further genetic and biochemical analyses indicated that the uncoordinated movements of these mutant filaments were correlated with the absence of cell surface fibril materials, indicating a possible new function for fibrils. PMID:10611358

  11. Identification and Characterization of a Putative Arginine Kinase Homolog from Myxococcus xanthus Required for Fruiting Body Formation and Cell Differentiation

    PubMed Central

    Bragg, Jonathan; Rajkovic, Andrei; Anderson, Chance; Curtis, Rachael; Van Houten, Jason; Begres, Brittany; Naples, Colin; Snider, Mark; Fraga, Dean

    2012-01-01

    Arginine kinases catalyze the reversible transfer of a high-energy phosphoryl group from ATP to l-arginine to form phosphoarginine, which is used as an energy buffer in insects, crustaceans, and some unicellular organisms. It plays an analogous role to that of phosphocreatine in vertebrates. Recently, putative arginine kinases were identified in several bacterial species, including the social Gram-negative soil bacterium Myxococcus xanthus. It is still unclear what role these proteins play in bacteria and whether they have evolved to acquire novel functions in the species in which they are found. In this study, we biochemically purified and characterized a putative M. xanthus arginine kinase, Ark, and demonstrated that it has retained the ability to catalyze the phosphorylation of arginine by using ATP. We also constructed a null mutation in the ark gene and demonstrated its role in both certain stress responses and development. PMID:22389486

  12. Transfer of plasmid RP4 to Myxococcus xanthus and evidence for its integration into the chromosome.

    PubMed Central

    Breton, A M; Jaoua, S; Guespin-Michel, J

    1985-01-01

    The broad-host-range plasmid RP4 and its derivative R68.45 were transferred to Myxococcus xanthus DK101 and DZ1; RP4 was maintained integrated in the chromosome. Loss of plasmid markers occurred during the growth of the transconjugants, which could be prevented by selective pressure with oxytetracycline. The integrated plasmid was transferred back to Escherichia coli often as RP4-prime plasmids carrying various segments of the M. xanthus chromosome. It also mediated chromosomal transfer between M. xanthus strains. Images PMID:3918015

  13. Regulation of Motility Behavior in Myxococcus xanthus May Require an Extracytoplasmic-Function Sigma Factor

    PubMed Central

    Ward, Mandy J.; Lew, Helen; Treuner-Lange, Anke; Zusman, David R.

    1998-01-01

    Using interaction trap technology, we identified a putative extracytoplasmic-function (ECF) sigma factor (RpoE1) in Myxococcus xanthus, a bacterium which has a complex life cycle that includes fruiting body formation. The first domain of the response regulator protein FrzZ, a component of the Frz signal transduction system, was used as bait. Although the RpoE1 protein displayed no interactions with control proteins presented as bait, a weak interaction with a second M. xanthus response regulator (AsgA) was observed. While the specificity of the FrzZ-RpoE1 interaction therefore remains speculative, cloning and sequencing of the region surrounding rpoE1 localized it to a position downstream of the frzZ gene. A potential promoter site for binding of an ECF sigma factor was identified upstream of rpoE1, suggesting the gene may be autoregulated. However, primer extension studies suggested that transcription of rpoE1 occurs under both vegetative and developmental conditions from a ς70-like promoter. Dot blot analysis of RNA preparations confirmed the low-level, constitutive expression of rpoE1 during both stages of the life cycle. Analysis of an insertion mutant also indicated a role for RpoE1 under both vegetative and developmental conditions, since swarming was reduced on nutrient-rich agar and developmental aggregation was effected under starvation conditions, especially at high cell densities. An insertion mutation introduced into the gene directly downstream of rpoE1 (orf5) did not result in either swarming or developmental aggregation defects, even though the gene is transcribed as part of the same operon. Therefore, we propose that this new ECF sigma factor could play a role in the transcriptional regulation of genes involved in motility behavior during both stages of the complex M. xanthus life cycle. PMID:9791117

  14. Bacterial Community Dynamics During the Application of a Myxococcus xanthus-Inoculated Culture Medium Used for Consolidation of Ornamental Limestone

    PubMed Central

    Jimenez-Lopez, Concepcion; Sterflinger, Katja; Ettenauer, Jörg; Jroundi, Fadwa; Fernandez-Vivas, Antonia; Gonzalez-Muñoz, Maria Teresa

    2010-01-01

    In this study, we investigated under laboratory conditions the bacterial communities inhabiting quarry and decayed ornamental carbonate stones before and after the application of a Myxococcus xanthus-inoculated culture medium used for consolidation of the stones. The dynamics of the community structure and the prevalence of the inoculated bacterium, M. xanthus, were monitored during the time course of the consolidation treatment (30 days). For this purpose, we selected a molecular strategy combining fingerprinting by denaturing gradient gel electrophoresis (DGGE) with the screening of eubacterial 16S rDNA clone libraries by DGGE and sequencing. Quantification of the inoculated strain was performed by quantitative real-time PCR (qPCR) using M. xanthus-specific primers designed in this work. Results derived from DGGE and sequencing analysis showed that, irrespective of the origin of the stone, the same carbonatogenic microorganisms were activated by the application of a M. xanthus culture. Those microorganisms were Pseudomonas sp., Bacillus sp., and Brevibacillus sp. The monitoring of M. xanthus in the culture media of treated stones during the time course experiment showed disparate results depending on the applied technique. By culture-dependent methods, the detection of this bacterium was only possible in the first day of the treatment, showing the limitation of these conventional techniques. By PCR-DGGE analysis, M. xanthus was detected during the first 3–6 days of the experiment. At this time, the population of this bacterium in the culture media varied between 108–106 cells ml−1, as showed by qPCR analyses. Thereafter, DGGE analyses showed to be not suitable for the detection of M. xanthus in a mixed culture. Nevertheless, qPCR analysis using specific primers for M. xanthus showed to be a more sensitive technique for the detection of this bacterium, revealing a population of 104 cells ml−1 in the culture media of both treated stones at the end of

  15. Cyclic Di-GMP Regulates Type IV Pilus-Dependent Motility in Myxococcus xanthus

    PubMed Central

    Skotnicka, Dorota; Petters, Tobias; Heering, Jan; Hoppert, Michael; Kaever, Volkhard

    2015-01-01

    ABSTRACT The nucleotide-based second messenger bis-(3′-5′)-cyclic dimeric GMP (c-di-GMP) is involved in regulating a plethora of processes in bacteria that are typically associated with lifestyle changes. Myxococcus xanthus undergoes major lifestyle changes in response to nutrient availability, with the formation of spreading colonies in the presence of nutrients and spore-filled fruiting bodies in the absence of nutrients. Here, we investigated the function of c-di-GMP in M. xanthus and show that this bacterium synthesizes c-di-GMP during growth. Manipulation of the c-di-GMP level by expression of either an active, heterologous diguanylate cyclase or an active, heterologous phosphodiesterase correlated with defects in type IV pilus (T4P)-dependent motility, whereas gliding motility was unaffected. An increased level of c-di-GMP correlated with reduced transcription of the pilA gene (which encodes the major pilin of T4P), reduced the assembly of T4P, and altered cell agglutination, whereas a decreased c-di-GMP level correlated with altered cell agglutination. The systematic inactivation of the 24 genes in M. xanthus encoding proteins containing GGDEF, EAL, or HD-GYP domains, which are associated with c-di-GMP synthesis, degradation, or binding, identified three genes encoding proteins important for T4P-dependent motility, whereas all mutants had normal gliding motility. Purified DmxA had diguanylate cyclase activity, whereas the hybrid histidine protein kinases TmoK and SgmT, each of which contains a GGDEF domain, did not have diguanylate cyclase activity. These results demonstrate that c-di-GMP is important for T4P-dependent motility in M. xanthus. IMPORTANCE We provide the first direct evidence that M. xanthus synthesizes c-di-GMP and demonstrate that c-di-GMP is important for T4P-dependent motility, whereas we did not obtain evidence that c-di-GMP regulates gliding motility. The data presented uncovered a novel mechanism for regulation of T4P

  16. Novel change in the carbohydrate portion of Myxococcus xanthus lipopolysaccharide during development.

    PubMed Central

    Panasenko, S M; Jann, B; Jann, K

    1989-01-01

    We have examined the alterations in lipopolysaccharide during aggregation and early development in Myxococcus xanthus. The lipopolysaccharide was isolated and characterized from cells developing on agar during glycerol induction and vegetative growth. A methylated amino sugar was identified as 6-O-methylgalactosamine by gas-liquid chromatography-mass spectrometry. This novel sugar was enriched in cells developing on agar. Images PMID:2495265

  17. Enzymatic and Functional Analysis of a Protein Phosphatase, Pph3, from Myxococcus xanthus

    PubMed Central

    Kimura, Yoshio; Mori, Yumi; Ina, Youhei; Takegawa, Kaoru

    2011-01-01

    A protein phosphatase, designated Pph3, from Myxococcus xanthus showed the enzymatic characteristics of PP2C-type serine/threonine protein phosphatases, which are metal ion-dependent, okadaic acid-insensitive protein phosphatases. The pph3 mutant under starvation conditions formed immature fruiting bodies and reduced sporulation. PMID:21398555

  18. Role of phase variation in the resistance of Myxococcus xanthus fruiting bodies to Caenorhabditis elegans predation.

    PubMed

    Dahl, John L; Ulrich, Christina H; Kroft, Tim L

    2011-10-01

    The phenomenon of phase variation between yellow and tan forms of Myxococcus xanthus has been recognized for several decades, but it is not known what role this variation may play in the ecology of myxobacteria. We confirm an earlier report that tan variants are disproportionately more numerous in the resulting spore population of a M. xanthus fruiting body than the tan vegetative cells that contributed to fruiting body formation. However, we found that tan cells may not require yellow cells for fruiting body formation or starvation-induced sporulation of tan cells. Here we report three differences between the yellow and tan variants that may play important roles in the soil ecology of M. xanthus. Specifically, the yellow variant is more capable of forming biofilms, is more sensitive to lysozyme, and is more resistant to ingestion by bacteriophagous nematodes. We also show that the myxobacterial fruiting body is more resistant to predation by worms than are dispersed M. xanthus cells. PMID:21821771

  19. A gene encoding a potential adenosine 5'-phosphosulphate kinase is necessary for timely development of Myxococcus xanthus.

    PubMed

    Wang, Daoyong; Xu, Shihui; Song, Dan; Knight, Stefan; Mao, Xiaohua

    2016-04-01

    A Myxococcus xanthus gene, MXAN3487, was identified by transposon mutagenesis to be required for the expression of mcuABC, an operon coding for part of the chaperone-usher (CU) system in this bacterium. The MXAN3487 protein displays sequence and structural homology to adenosine 5'-phosphosulphate (APS) kinase family members and contains putative motifs for ATP and APS binding. Although the MXAN3487 locus is not linked to other sulphate assimilation genes, its protein product may have APS kinase activity in vivo and the importance of the ATP-binding site for activity was demonstrated. Expression of MXAN3487 was not affected by sulphate availability, suggesting that MXAN3487 may not function in a reductive sulphate assimilation pathway. Deletion of MXAN3487 significantly delayed fruiting body formation and the production of McuA, a spore coat protein secreted by the M. xanthus Mcu CU system. Based on these observations and data from our previous studies, we propose that MXAN3487 may phosphorylate molecules structurally related to APS, generating metabolites necessary for M. xanthus development, and that MXAN3487 exerts a positive effect on the mcuABC operon whose expression is morphogenesis dependent. PMID:26860640

  20. Cloning and Expression of clt Genes Encoding Milk-Clotting Proteases from Myxococcus xanthus 422

    PubMed Central

    Poza, M.; Prieto-Alcedo, M.; Sieiro, C.; Villa, T. G.

    2004-01-01

    The screening of a gene library of the milk-clotting strain Myxococcus xanthus 422 constructed in Escherichia coli allowed the description of eight positive clones containing 26 open reading frames. Only three of them (cltA, cltB, and cltC) encoded proteins that exhibited intracellular milk-clotting ability in E. coli, Saccharomyces cerevisiae, and Pichia pastoris expression systems. PMID:15466588

  1. Lipid body formation plays a central role in cell fate determination during developmental differentiation of Myxococcus xanthus

    PubMed Central

    Ring, Michael W.; McHugh, Colleen A.; Schwär, Gertrud; Bode, Edna; Krug, Daniel; Altmeyer, Matthias O.; Lu, Jeff Zhiqiang

    2010-01-01

    Summary Cell differentiation is widespread during the development of multicellular organisms, but rarely observed in prokaryotes. One example of prokaryotic differentiation is the Gramnegative bacterium Myxococcus xanthus. In response to starvation, this gliding bacterium initiates a complex developmental program that results in the formation of spore-filled fruiting bodies. How the cells metabolically support the necessary complex cellular differentiation from rod-shaped vegetative cells into spherical spores is unknown. Here, we present evidence that intra-cellular lipid bodies provide the necessary metabolic fuel for the development of spores. Formed at the onset of starvation, these lipid bodies gradually disappear until they are completely used up by the time the cells have become mature spores. Moreover, it appears that lipid body formation in M. xanthus is an important initial step indicating cell fate during differentiation. Upon starvation, two subpopulations of cells occur: cells that form lipid bodies invariably develop into spores, while cells that do not form lipid bodies end up becoming peripheral rods, which are cells that lack signs of morphological differentiation and stay in a vegetative-like state. These data indicate that lipid bodies not only fuel cellular differentiation but that their formation represents the first known morphological sign indicating cell fate during differentiation. PMID:19788540

  2. Mutations that confer resistance to 2-deoxyglucose reduce the specific activity of hexokinase from Myxococcus xanthus.

    PubMed

    Youderian, P; Lawes, M C; Creighton, C; Cook, J C; Saier, M H

    1999-04-01

    The glucose analog 2-deoxyglucose (2dGlc) inhibits the growth and multicellular development of Myxococcus xanthus. Mutants of M. xanthus resistant to 2dGlc, designated hex mutants, arise at a low spontaneous frequency. Expression of the Escherichia coli glk (glucokinase) gene in M. xanthus hex mutants restores 2dGlc sensitivity, suggesting that these mutants arise upon the loss of a soluble hexokinase function that phosphorylates 2dGlc to form the toxic intermediate, 2-deoxyglucose-6-phosphate. Enzyme assays of M. xanthus extracts reveal a soluble hexokinase (ATP:D-hexose-6-phosphotransferase; EC 2.7.1.1) activity but no phosphotransferase system activities. The hex mutants have lower levels of hexokinase activities than the wild type, and the levels of hexokinase activity exhibited by the hex mutants are inversely correlated with the ability of 2dGlc to inhibit their growth and sporulation. Both 2dGlc and N-acetylglucosamine act as inhibitors of glucose turnover by the M. xanthus hexokinase in vitro, consistent with the finding that glucose and N-acetylglucosamine can antagonize the toxic effects of 2dGlc in vivo. PMID:10094702

  3. An ABC Transporter Plays a Developmental Aggregation Role in Myxococcus xanthus

    PubMed Central

    Ward, Mandy J.; Mok, Kenny C.; Astling, David P.; Lew, Helen; Zusman, David R.

    1998-01-01

    Myxococcus xanthus is a gram-negative bacterium which has a complex life cycle. Autochemotaxis, a process whereby cells release a self-generated signaling molecule, may be the principal mechanism facilitating directed motility in both the vegetative swarming and developmental aggregation stages of this life cycle. The process requires the Frz signal transduction system, including FrzZ, a protein which is composed of two domains, both showing homology to the enteric chemotaxis response regulator CheY. The first domain of FrzZ (FrzZ1), when expressed as bait in the yeast two-hybrid system and screened against a library, was shown to potentially interact with the C-terminal portion of a protein encoding an ATP-binding cassette (AbcA). The activation domain-AbcA fusion protein did not interact with the second domain of FrzZ (FrzZ2) or with two other M. xanthus response regulator-containing proteins presented as bait, suggesting that the FrzZ1-AbcA interaction may be specific. Cloning and sequencing of the upstream region of the abcA gene showed the ATP-binding cassette to be linked to a large hydrophobic, potentially membrane-spanning domain. This domain organization is characteristic of a subgroup of ABC transporters which perform export functions. Cloning and sequencing downstream of abcA indicated that the ABC transporter is at the start of an operon containing three open reading frames. An insertion mutation in the abcA gene resulted in cells displaying the frizzy aggregation phenotype, providing additional evidence that FrzZ and AbcA may be part of the same signal transduction pathway. Cells with mutations in genes downstream of abcA showed no developmental defects. Analysis of the proposed exporter role of AbcA in cell mixing experiments showed that the ABC transporter mutant could be rescued by extracellular complementation. We speculate that the AbcA protein may be involved in the export of a molecule required for the autochemotactic process. PMID:9791121

  4. Directional reversals enable Myxococcus xanthus cells to produce collective one-dimensional streams during fruiting-body formation.

    PubMed

    Thutupalli, Shashi; Sun, Mingzhai; Bunyak, Filiz; Palaniappan, Kannappan; Shaevitz, Joshua W

    2015-08-01

    The formation of a collectively moving group benefits individuals within a population in a variety of ways. The surface-dwelling bacterium Myxococcus xanthus forms dynamic collective groups both to feed on prey and to aggregate during times of starvation. The latter behaviour, termed fruiting-body formation, involves a complex, coordinated series of density changes that ultimately lead to three-dimensional aggregates comprising hundreds of thousands of cells and spores. How a loose, two-dimensional sheet of motile cells produces a fixed aggregate has remained a mystery as current models of aggregation are either inconsistent with experimental data or ultimately predict unstable structures that do not remain fixed in space. Here, we use high-resolution microscopy and computer vision software to spatio-temporally track the motion of thousands of individuals during the initial stages of fruiting-body formation. We find that cells undergo a phase transition from exploratory flocking, in which unstable cell groups move rapidly and coherently over long distances, to a reversal-mediated localization into one-dimensional growing streams that are inherently stable in space. These observations identify a new phase of active collective behaviour and answer a long-standing open question in Myxococcus development by describing how motile cell groups can remain statistically fixed in a spatial location. PMID:26246416

  5. Directional reversals enable Myxococcus xanthus cells to produce collective one-dimensional streams during fruiting-body formation

    PubMed Central

    Thutupalli, Shashi; Sun, Mingzhai; Bunyak, Filiz; Palaniappan, Kannappan; Shaevitz, Joshua W.

    2015-01-01

    The formation of a collectively moving group benefits individuals within a population in a variety of ways. The surface-dwelling bacterium Myxococcus xanthus forms dynamic collective groups both to feed on prey and to aggregate during times of starvation. The latter behaviour, termed fruiting-body formation, involves a complex, coordinated series of density changes that ultimately lead to three-dimensional aggregates comprising hundreds of thousands of cells and spores. How a loose, two-dimensional sheet of motile cells produces a fixed aggregate has remained a mystery as current models of aggregation are either inconsistent with experimental data or ultimately predict unstable structures that do not remain fixed in space. Here, we use high-resolution microscopy and computer vision software to spatio-temporally track the motion of thousands of individuals during the initial stages of fruiting-body formation. We find that cells undergo a phase transition from exploratory flocking, in which unstable cell groups move rapidly and coherently over long distances, to a reversal-mediated localization into one-dimensional growing streams that are inherently stable in space. These observations identify a new phase of active collective behaviour and answer a long-standing open question in Myxococcus development by describing how motile cell groups can remain statistically fixed in a spatial location. PMID:26246416

  6. Activation of 6-phosphofructokinase via phosphorylation by Pkn4, a protein Ser/Thr kinase of Myxococcus xanthus.

    PubMed

    Nariya, Hirofumi; Inouye, Sumiko

    2002-12-01

    Myxococcus xanthus is a Gram-negative bacterium that exhibits a communal lifestyle during vegetative growth and multicellular development, forming fruiting bodies filled with spores. It contains at least 13 eukaryotic-like protein Ser/Thr kinases (PSTKs from Pkn1 to Pkn13). In the present report, we demonstrate that Pkn4, the gene located 18 bp downstream of the gene for 6-phosphofructokinase (PFK), is a PSTK for M. xanthus PFK (Mx-PFK), the key regulatory enzyme in glycolysis. Both Pkn4 and Mx-PFK were expressed in Escherichia coli and purified. Mx-PFK was found to be phosphorylated by Pkn4 at Thr-226, which is presumed to be located in the allosteric effector site of the PFK. The phosphorylation of Mx-PFK enhanced its activity 2.7-fold, indicating that Pkn4 plays an important role in glucose metabolism. Although PFKs from other organisms are known to be tetrameric enzymes, Mx-PFK is composed of an octamer and is dissociated to tetramers in the presence of phosphoenolpyruvate (PEP), an allosteric inhibitor for PFK. Furthermore, phosphorylation of PFK by Pkn4 is almost completely inhibited by PEP. Mx-PFK is associated with the regulatory domain of Pkn4, and this association is inhibited by PEP. This is the first demonstration that a prokaryotic PFK is regulated by phosphorylation by PSTK in prokaryotes. PMID:12453221

  7. Myxospore formation in Myxococcus xanthus: chemical changes in the cell wall during cellular morphogenesis.

    PubMed

    Johnson, R Y; White, D

    1972-11-01

    Vegetative cells of Myxococcus xanthus (strain FB) were induced to form myxospores by the glycerol induction technique. Several structural changes took place in the peptidoglycan during myxospore formation. The percent of the peptidoglycan comprised of monomer (disaccharide peptide) decreased from about 20% to approximately 7%. The proportion of the total diaminopimelic acid possessing a free amino group decreased about 11%. A carbohydrate containing only glucose was found to be bound, possibly covalently, to the vegetative cell and myxospore peptidoglycan. The amount of carbohydrate relative to peptidoglycan decreased by two-thirds during myxospore formation. None of the above changes in the peptidoglycan were observed in a mutant (strain GNI) of M. xanthus which was unable to convert to myxospores when incubated in the glycerol induction medium, or in the parental wild type (FB) when it was incubated in induction medium lacking the myxospore inducer, glycerol. PMID:5086662

  8. Purification and Properties of Myxococcus xanthus C-Factor, an Intercellular Signaling Protein

    NASA Astrophysics Data System (ADS)

    Kim, Seung K.; Kaiser, Dale

    1990-05-01

    C-factor, a Myxococcus xanthus protein that restores the developmental defects of a class of nonautonomous mutants resulting from mutation of the csgA gene, has been purified approximately 1000-fold from starved wild-type cells. The monomeric form of C-factor is a single polypeptide with a molecular mass of 17 kDa that can be solubilized by detergent from membrane components. Characterization by gel filtration and denaturing gel electrophoresis suggests that biologically active C-factor is a dimer composed of two 17-kDa monomers. Antibodies against a form of the M. xanthus csgA gene product overexpressed in Escherichia coli react with purified C-factor.

  9. A Minimal Threshold of c-di-GMP Is Essential for Fruiting Body Formation and Sporulation in Myxococcus xanthus

    PubMed Central

    Skotnicka, Dorota; Trampari, Eleftheria; Liang, Jennifer; Kaever, Volkhard; Malone, Jacob G.; Singer, Mitchell; Søgaard-Andersen, Lotte

    2016-01-01

    Generally, the second messenger bis-(3’-5’)-cyclic dimeric GMP (c-di-GMP) regulates the switch between motile and sessile lifestyles in bacteria. Here, we show that c-di-GMP is an essential regulator of multicellular development in the social bacterium Myxococcus xanthus. In response to starvation, M. xanthus initiates a developmental program that culminates in formation of spore-filled fruiting bodies. We show that c-di-GMP accumulates at elevated levels during development and that this increase is essential for completion of development whereas excess c-di-GMP does not interfere with development. MXAN3735 (renamed DmxB) is identified as a diguanylate cyclase that only functions during development and is responsible for this increased c-di-GMP accumulation. DmxB synthesis is induced in response to starvation, thereby restricting DmxB activity to development. DmxB is essential for development and functions downstream of the Dif chemosensory system to stimulate exopolysaccharide accumulation by inducing transcription of a subset of the genes encoding proteins involved in exopolysaccharide synthesis. The developmental defects in the dmxB mutant are non-cell autonomous and rescued by co-development with a strain proficient in exopolysaccharide synthesis, suggesting reduced exopolysaccharide accumulation as the causative defect in this mutant. The NtrC-like transcriptional regulator EpsI/Nla24, which is required for exopolysaccharide accumulation, is identified as a c-di-GMP receptor, and thus a putative target for DmxB generated c-di-GMP. Because DmxB can be—at least partially—functionally replaced by a heterologous diguanylate cyclase, these results altogether suggest a model in which a minimum threshold level of c-di-GMP is essential for the successful completion of multicellular development in M. xanthus. PMID:27214040

  10. The mysterious nature of bacterial surface (gliding) motility: A focal adhesion-based mechanism in Myxococcus xanthus.

    PubMed

    Islam, Salim T; Mignot, Tâm

    2015-10-01

    Motility of bacterial cells promotes a range of important physiological phenomena such as nutrient detection, harm avoidance, biofilm formation, and pathogenesis. While much research has been devoted to the mechanism of bacterial swimming in liquid via rotation of flagellar filaments, the mechanisms of bacterial translocation across solid surfaces are poorly understood, particularly when cells lack external appendages such as rotary flagella and/or retractile type IV pili. Under such limitations, diverse bacteria at the single-cell level are still able to "glide" across solid surfaces, exhibiting smooth translocation of the cell along its long axis. Though multiple gliding mechanisms have evolved in different bacterial classes, most remain poorly characterized. One exception is the gliding motility mechanism used by the Gram-negative social predatory bacterium Myxococcus xanthus. The available body of research suggests that M. xanthus gliding motility is mediated by trafficked multi-protein (Glt) cell envelope complexes, powered by proton-driven flagellar stator homologues (Agl). Through coupling to the substratum via polysaccharide slime, Agl-Glt assemblies can become fixed relative to the substratum, forming a focal adhesion site. Continued directional transport of slime-associated substratum-fixed Agl-Glt complexes would result in smooth forward movement of the cell. In this review, we have provided a comprehensive synthesis of the latest mechanistic and structural data for focal adhesion-mediated gliding motility in M. xanthus, with emphasis on the role of each Agl and Glt protein. Finally, we have also highlighted the possible connection between the motility complex and a new type of spore coat assembly system, suggesting that gliding and cell envelope synthetic complexes are evolutionarily linked. PMID:26520023

  11. A Minimal Threshold of c-di-GMP Is Essential for Fruiting Body Formation and Sporulation in Myxococcus xanthus.

    PubMed

    Skotnicka, Dorota; Smaldone, Gregory T; Petters, Tobias; Trampari, Eleftheria; Liang, Jennifer; Kaever, Volkhard; Malone, Jacob G; Singer, Mitchell; Søgaard-Andersen, Lotte

    2016-05-01

    Generally, the second messenger bis-(3'-5')-cyclic dimeric GMP (c-di-GMP) regulates the switch between motile and sessile lifestyles in bacteria. Here, we show that c-di-GMP is an essential regulator of multicellular development in the social bacterium Myxococcus xanthus. In response to starvation, M. xanthus initiates a developmental program that culminates in formation of spore-filled fruiting bodies. We show that c-di-GMP accumulates at elevated levels during development and that this increase is essential for completion of development whereas excess c-di-GMP does not interfere with development. MXAN3735 (renamed DmxB) is identified as a diguanylate cyclase that only functions during development and is responsible for this increased c-di-GMP accumulation. DmxB synthesis is induced in response to starvation, thereby restricting DmxB activity to development. DmxB is essential for development and functions downstream of the Dif chemosensory system to stimulate exopolysaccharide accumulation by inducing transcription of a subset of the genes encoding proteins involved in exopolysaccharide synthesis. The developmental defects in the dmxB mutant are non-cell autonomous and rescued by co-development with a strain proficient in exopolysaccharide synthesis, suggesting reduced exopolysaccharide accumulation as the causative defect in this mutant. The NtrC-like transcriptional regulator EpsI/Nla24, which is required for exopolysaccharide accumulation, is identified as a c-di-GMP receptor, and thus a putative target for DmxB generated c-di-GMP. Because DmxB can be-at least partially-functionally replaced by a heterologous diguanylate cyclase, these results altogether suggest a model in which a minimum threshold level of c-di-GMP is essential for the successful completion of multicellular development in M. xanthus. PMID:27214040

  12. A Myxococcus xanthus Bacterial Tyrosine Kinase, BtkA, Is Required for the Formation of Mature Spores▿

    PubMed Central

    Kimura, Yoshio; Yamashita, Shinji; Mori, Yumi; Kitajima, Yuki; Takegawa, Kaoru

    2011-01-01

    A Myxococcus xanthus cytoplasmic bacterial tyrosine kinase, BtkA, showed phosphorylation activity in the presence of Exo. Phosphorylated BtkA was expressed late after starvation induction and early after glycerol induction. The btkA mutant was unable to complete maturation to heat- and sonication-resistant spores under both starvation- and glycerol-induced developmental conditions. PMID:21840977

  13. Genetic studies of mrp, a locus essential for cellular aggregation and sporulation of Myxococcus xanthus.

    PubMed

    Sun, H; Shi, W

    2001-08-01

    Under starvation conditions, Myxococcus xanthus undergoes a complex developmental process which includes cellular aggregation and sporulation. A transposon insertion mutant (the Tn5-Omega280 mutant) with defects in both aggregation and sporulation was analyzed in this study. The Tn5-Omega280 mutant was found to have a disrupted NtrC-like response regulator designated Myxococcus regulatory protein B (mrpB). Further sequencing analyses revealed a histidine kinase homolog (mrpA) immediately upstream of mrpB and a cyclic AMP receptor protein-like transcriptional regulator (mrpC) downstream of mrpB. In-frame deletion analyses revealed that both the mrpB and mrpC genes were required for cellular aggregation and sporulation but that only mrpA was required for sporulation only. Site-specific mutagenesis of the putative phosphorylation site of MrpB, D58, showed that a D58A mutation caused defects in both aggregation and sporulation but that a D58E mutation resulted in only a sporulation defect. Further genetic and molecular analyses with reporter genes and reverse transcription-PCR indicated that mrpA and mrpB are cotranscribed but that mrpC is transcribed independently and that all of these genes are developmentally regulated. In addition, MrpB is essential for transcription of mrpC and MrpC regulates its own transcription. These data indicate that Mrp proteins are important components required for M. xanthus development. The complicated interaction between Mrp proteins may play an important role in regulating developmental gene expression in M. xanthus. PMID:11466282

  14. devI Is an Evolutionarily Young Negative Regulator of Myxococcus xanthus Development

    PubMed Central

    Rajagopalan, Ramya; Wielgoss, Sébastien; Lippert, Gerardo; Velicer, Gregory J.

    2015-01-01

    ABSTRACT During starvation-induced development of Myxococcus xanthus, thousands of rod-shaped cells form mounds in which they differentiate into spores. The dev locus includes eight genes followed by clustered regularly interspaced short palindromic repeats (CRISPRs), comprising a CRISPR-Cas system (Cas stands for CRISPR associated) typically involved in RNA interference. Mutations in devS or devR of a lab reference strain permit mound formation but impair sporulation. We report that natural isolates of M. xanthus capable of normal development are highly polymorphic in the promoter region of the dev operon. We show that the dev promoter is predicted to be nonfunctional in most natural isolates and is dispensable for development of a laboratory reference strain. Moreover, deletion of the dev promoter or the small gene immediately downstream of it, here designated devI (development inhibitor), suppressed the sporulation defect of devS or devR mutants in the lab strain. Complementation experiments and the result of introducing a premature stop codon in devI support a model in which DevRS proteins negatively autoregulate expression of devI, whose 40-residue protein product DevI inhibits sporulation if overexpressed. DevI appears to act in a cell-autonomous manner since experiments with conditioned medium and with cell mixtures gave no indication of extracellular effects. Strikingly, we report that devI is entirely absent from most M. xanthus natural isolates and was only recently integrated into the developmental programs of some lineages. These results provide important new insights into both the evolutionary history of the dev operon and its mechanistic role in M. xanthus sporulation. IMPORTANCE Certain mutations in the dev CRISPR-Cas (clustered regularly interspaced short palindromic repeat-associated) system of Myxococcus xanthus impair sporulation. The link between development and a CRISPR-Cas system has been a mystery. Surprisingly, DNA sequencing of natural

  15. Describing Myxococcus xanthus Aggregation Using Ostwald Ripening Equations for Thin Liquid Films

    PubMed Central

    Bahar, Fatmagül; Pratt-Szeliga, Philip C.; Angus, Stuart; Guo, Jiaye; Welch, Roy D.

    2014-01-01

    When starved, a swarm of millions of Myxococcus xanthus cells coordinate their movement from outward swarming to inward coalescence. The cells then execute a synchronous program of multicellular development, arranging themselves into dome shaped aggregates. Over the course of development, about half of the initial aggregates disappear, while others persist and mature into fruiting bodies. This work seeks to develop a quantitative model for aggregation that accurately simulates which will disappear and which will persist. We analyzed time-lapse movies of M. xanthus development, modeled aggregation using the equations that describe Ostwald ripening of droplets in thin liquid films, and predicted the disappearance and persistence of aggregates with an average accuracy of 85%. We then experimentally validated a prediction that is fundamental to this model by tracking individual fluorescent cells as they moved between aggregates and demonstrating that cell movement towards and away from aggregates correlates with aggregate disappearance. Describing development through this model may limit the number and type of molecular genetic signals needed to complete M. xanthus development, and it provides numerous additional testable predictions. PMID:25231319

  16. Mutations that affect production of branched RNA-linked msDNA in Myxococcus xanthus.

    PubMed Central

    Dhundale, A; Furuichi, T; Inouye, M; Inouye, S

    1988-01-01

    A deletion mutation of the gene (msd-msr) for the branched RNA-linked msDNA of Myxococcus xanthus was constructed by replacing the chromosomal 0.7-kilobase (kb) SmaI-XhoI fragment encompassing msd-msr with a 1.4-kb fragment carrying a gene for kanamycin resistance. It was found that this deletion strain (delta msSX) could not produce msDNA, although it still contained another species of msDNA, mrDNA (msDNA, reduced size). No apparent differences between delta msSX and the wild-type strain were observed in terms of cell growth, morphogenesis, fruiting-body formation, or motility. Both a deletion mutation at the region 100 base pairs upstream of msd and an insertion mutation at a site 500 base pairs upstream of msd showed a significant reduction of msDNA production, indicating that there is a cis- or trans-acting positive element in this region. When the 3.5-kb BamHI fragment carrying msd-msr from Stigmatella aurantiaca was inserted into the M. xanthus chromosome, the S. aurantiaca msDNA was found to be produced in M. xanthus. Images PMID:2461359

  17. Genome Evolution and the Emergence of Fruiting Body Development in Myxococcus xanthus

    PubMed Central

    Goldman, Barry; Bhat, Swapna; Shimkets, Lawrence J.

    2007-01-01

    Background Lateral gene transfer (LGT) is thought to promote speciation in bacteria, though well-defined examples have not been put forward. Methodology/Principle Findings We examined the evolutionary history of the genes essential for a trait that defines a phylogenetic order, namely fruiting body development of the Myxococcales. Seventy-eight genes that are essential for Myxococcus xanthus development were examined for LGT. About 73% of the genes exhibit a phylogeny similar to that of the 16S rDNA gene and a codon bias consistent with other M. xanthus genes suggesting vertical transmission. About 22% have an altered codon bias and/or phylogeny suggestive of LGT. The remaining 5% are unique. Genes encoding signal production and sensory transduction were more likely to be transmitted vertically with clear examples of duplication and divergence into multigene families. Genes encoding metabolic enzymes were frequently acquired by LGT. Myxobacteria exhibit aerobic respiration unlike most of the δ Proteobacteria. M. xanthus contains a unique electron transport pathway shaped by LGT of genes for succinate dehydrogenase and three cytochrome oxidase complexes. Conclusions/Significance Fruiting body development depends on genes acquired by LGT, particularly those involved in polysaccharide production. We suggest that aerobic growth fostered innovation necessary for development by allowing myxobacteria access to a different gene pool from anaerobic members of the δ Proteobacteria. Habitat destruction and loss of species diversity could restrict the evolution of new bacterial groups by limiting the size of the prospective gene pool. PMID:18159227

  18. MglC, a Paralog of Myxococcus xanthus GTPase-Activating Protein MglB, Plays a Divergent Role in Motility Regulation

    PubMed Central

    McLoon, Anna L.; Wuichet, Kristin; Häsler, Michael; Keilberg, Daniela; Szadkowski, Dobromir

    2015-01-01

    ABSTRACT In order to optimize interactions with their environment and one another, bacteria regulate their motility. In the case of the rod-shaped cells of Myxococcus xanthus, regulated motility is essential for social behaviors. M. xanthus moves over surfaces using type IV pilus-dependent motility and gliding motility. These two motility systems are coordinated by a protein module that controls cell polarity and consists of three polarly localized proteins, the small G protein MglA, the cognate MglA GTPase-activating protein MglB, and the response regulator RomR. Cellular reversals are induced by the Frz chemosensory system, and the output response regulator of this system, FrzZ, interfaces with the MglA/MglB/RomR module to invert cell polarity. Using a computational approach, we identify a paralog of MglB, MXAN_5770 (MglC). Genetic epistasis experiments demonstrate that MglC functions in the same pathway as MglA, MglB, RomR, and FrzZ and is important for regulating cellular reversals. Like MglB, MglC localizes to the cell poles asymmetrically and with a large cluster at the lagging pole. Correct polar localization of MglC depends on RomR and MglB. Consistently, MglC interacts directly with MglB and the C-terminal output domain of RomR, and we identified a surface of MglC that is necessary for the interaction with MglB and for MglC function. Together, our findings identify an additional member of the M. xanthus polarity module involved in regulating motility and demonstrate how gene duplication followed by functional divergence can add a layer of control to the complex cellular processes of motility and motility regulation. IMPORTANCE Gene duplication and the subsequent divergence of the duplicated genes are important evolutionary mechanisms for increasing both biological complexity and regulation of biological processes. The bacterium Myxococcus xanthus is a soil bacterium with an unusually large genome that carries out several social processes, including

  19. Similarity between the Myxococcus xanthus and Stigmatella aurantiaca reverse transcriptase genes associated with multicopy, single-stranded DNA.

    PubMed Central

    Hsu, M Y; Xu, C; Inouye, M; Inouye, S

    1992-01-01

    To determine the evolutional relationship of bacterial retroelements of Myxococcus xanthus and Stigmatella aurantiaca, the nucleotide sequence of 3,060 bases encompassing msr, msd, and the upstream region of msd (downstream of msr) of S. aurantiaca DW4 was determined and compared with the same region from M. xanthus. An open reading frame was found 92 bases upstream of msd which encoded a polypeptide of 480 amino acid residues having 73% identity with the reverse transcriptase of M. xanthus. Together with high homologies in msr (86%) and msd (81%) regions, the present data indicate that the reverse transcriptase genes as well as the retrons of M. xanthus (retron-Mx162) and S. aurantiaca (retron-Sa163) were derived from a common progenitor retron which possibly before the two myxobacterial species diverged. PMID:1372604

  20. Ribonucleic acid synthesis during fruiting body formation in Myxococcus xanthus.

    PubMed

    Smith, B A; Dworkin, M

    1981-04-01

    A method has been devised that allowed us, for the first time, to pulse-label M. xanthus cells with precursors for ribonucleic acid biosynthesis while they were undergoing fruiting body formation. Using this method, we examined patterns of ribonucleic acid (RNA) accumulation throughout the process of fruiting body formation. As development proceeded, the rate of RNA accumulation increased at two periods of the developmental cycle: once just before aggregation and once late in the cycle, when sporulation was essentially completed. In contrast to vegetatively growing cells, in which only stable RNA species are labeled during a 30-min pulse, the majority of radioactivity found in RNA from 30-min pulse-labeled developing cells was found in an unstable heterodisperse fraction that migrated to the 5S to 16S region of sucrose density gradients and sodium dodecyl sulfate-polyacrylamide gels. This pattern of incorporation could not be induced (i) by a shift down of vegetatively growing cells to a nutritionally poor medium, in which the generation time was increased to that of developing cells during the growth phase, or (ii) by plating of vegetative cells onto the same solid-surface environment as that of developing cells, but which surface supported vegetative growth rather than fruiting body formation. Thus, the RNA synthesis pattern observed appeared to be related to development per se rather than to nutritional depletion or growth on a solid surface alone. The radioactivity incorporated into the unstable 5S to 16S RNA fraction accumulated as the pulse length was increased from 10 to 30 min; in contrast, an analogous unstable fraction from vegetative cells decreased as pulse length was increased. This suggested that developmental 5S to 16S RNA was more stable than vegetative cell 5S to 16S RNA (presumptive messenger RNA). However, during a 45-min chase period, radioactivity in 30-min-pulse-labeled developmental 5S to 16S RNA decayed to an extent twice that of

  1. Comparative intermediary metabolism of vegetative cells and microcysts of Myxococcus xanthus.

    PubMed

    Watson, B F; Dworkin, M

    1968-11-01

    Crude extracts of both vegetative cells and glycerol-induced microcysts of Myxococcus xanthus contained the following enzyme activities: phosphofructokinase, phosphoglucoisomerase, fructose-1,6-diphosphatase, fructosediphosphate aldolase, glyceraldehyde-3-phosphate dehydrogenase, phosphopyruvate carboxylase, citrate synthase, isocitrate dehydrogenase, alpha-ketoglutarate dehydrogenase, succinate dehydrogenase, malate dehydrogenase, glucose-6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase, phosphoglucomutase, and uridine diphosphate glucose pyrophosphorylase. With the exception of isocitrate dehydrogenase, which was present at a fivefold higher concentration in microcysts, all activities in extracts from both types of cells were essentially equal. Hexokinase and pyruvate kinase could not be detected in extracts from either type of cell. Microcysts metabolized acetate at a lower rate than did vegetative cells. Most of this decrease was reflected in a substantial decrease in ability of microcysts to oxidize acetate to CO(2). In addition, microcysts and vegetative cells showed a different distribution of (14)C-label from incorporated acetate. PMID:4302296

  2. Deoxyribonucleic Acid Synthesis During Exponential Growth and Microcyst Formation in Myxococcus xanthus

    PubMed Central

    Rosenberg, Eugene; Katarski, Mary; Gottlieb, Peter

    1967-01-01

    Myxococcus xanthus in exponential phase with a generation time of 270 min contained a period of 50 min during which deoxyribonucleic acid (DNA) synthesis did not take place. After induction of microcysts by the glycerol technique, the DNA content increased 19%. Autoradiographic experiments demonstrated that the DNA made after glycerol induction was not evenly distributed among the microcysts. The distribution of grains per microcyst fits the following model of chromosome replication: in exponential phase, each daughter cell receives two chromosomes which are replicated sequentially during 80% of the divison cycle; after microcyst induction, no chromosomes are initiated. Mathematical formulas were derived which predict the kinetics and discrete probability distribution for several chromosome models. PMID:6032514

  3. Comparative Intermediary Metabolism of Vegetative Cells and Microcysts of Myxococcus xanthus1

    PubMed Central

    Watson, Benjamin F.; Dworkin, Martin

    1968-01-01

    Crude extracts of both vegetative cells and glycerol-induced microcysts of Myxococcus xanthus contained the following enzyme activities: phosphofructokinase, phosphoglucoisomerase, fructose-1,6-diphosphatase, fructosediphosphate aldolase, glyceraldehyde-3-phosphate dehydrogenase, phosphopyruvate carboxylase, citrate synthase, isocitrate dehydrogenase, α-ketoglutarate dehydrogenase, succinate dehydrogenase, malate dehydrogenase, glucose-6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase, phosphoglucomutase, and uridine diphosphate glucose pyrophosphorylase. With the exception of isocitrate dehydrogenase, which was present at a fivefold higher concentration in microcysts, all activities in extracts from both types of cells were essentially equal. Hexokinase and pyruvate kinase could not be detected in extracts from either type of cell. Microcysts metabolized acetate at a lower rate than did vegetative cells. Most of this decrease was reflected in a substantial decrease in ability of microcysts to oxidize acetate to CO2. In addition, microcysts and vegetative cells showed a different distribution of 14C-label from incorporated acetate. PMID:4302296

  4. An Adenylyl Cyclase, CyaB, Acts as an Osmosensor in Myxococcus xanthus

    PubMed Central

    Kimura, Yoshio; Ohtani, Mika; Takegawa, Kaoru

    2005-01-01

    We have previously reported that a receptor-type adenylyl cyclase (CyaA) of Myxococcus xanthus undergoes an osmosensor mainly during spore germination (Y. Kimura et al., J. Bacteriol. 184:3578-3585, 2002). In the present study, we cloned another receptor-type adenylyl cyclase gene (cyaB) and characterized the function of the cyaB-encoded protein. Disruption of cyaB generates a mutant that showed growth retardation at high ionic (NaCl) or high nonionic (sucrose) osmolarity. When vegetative cells were stimulated with 0.15 M NaCl, the increases in intracellular cyclic AMP levels of cyaB mutant cells were lower than those of wild-type cells. Under nonionic osmostress, the cyaB mutant exhibited reduced spore germination; however, the germination rate of the cyaB mutant was significantly higher than that of the cyaA mutant. PMID:15866951

  5. The orphan response regulator EpsW is a substrate of the DifE kinase and it regulates exopolysaccharide in Myxococcus xanthus

    PubMed Central

    Black, Wesley P.; Wang, Lingling; Davis, Manli Y.; Yang, Zhaomin

    2015-01-01

    Here we attempted to identify the downstream target of the DifE histidine kinase in the regulation of exopolysaccharide (EPS) production in the Gram-negative bacterium Myxococcus xanthus. This bacterium is an important model system for the studies of Type IV pilus (T4P) because it is motile by social (S) motility which is powered by T4P retraction. EPS is critical for S motility because it is the preferred anchor for T4P retraction in this bacterium. Previous studies identified the Dif chemosensory pathway as crucial for the regulation of EPS production. However, the downstream target of the DifE kinase in this pathway was unknown. In this study, EpsW, an orphan and single-domain response regulator (RR), was identified as a potential DifE target first by bioinformatics. Subsequent experiments demonstrated that epsW is essential for EPS biosynthesis in vivo and that EpsW is directly phosphorylated by DifE in vitro. Targted mutagenesis of epsW suggests that EpsW is unlikely the terminal RR of the Dif pathway. We propose instead that EpsW is an intermediary in a multistep phosphorelay that regulates EPS in M. xanthus. PMID:26639551

  6. Herbicidal and antioxidant responses of transgenic rice overexpressing Myxococcus xanthus protoporphyrinogen oxidase.

    PubMed

    Jung, Sunyo; Back, Kyoungwhan

    2005-05-01

    We analyzed the herbicidal and antioxidant defense responses of transgenic rice plants that overexpressed the Myxococcus xanthus protoporphyrinogen oxidase gene. Leaf squares of the wild-type incubated with oxyfluorfen were characterized by necrotic leaf lesions and increases in conductivity and malonyldialdehyde levels, whereas transgenic lines M4 and M7 did not show any change with up to 100 microM oxyfluorfen. The wild-type had decreased F(v)/F(m) and produced a high level of H(2)O(2) at 18 h after foliar application of oxyfluorfen, whereas transgenic lines M4 and M7 were unaffected. In response to oxyfluorfen, violaxanthin, beta-carotene, and chlorophylls (Chls) decreased in wild-type plants, whereas antheraxanthin and zeaxanthin increased. Only a slight decline in Chls was observed in transgenic lines at 48 h after oxyfluorfen treatment. Noticeable increases of cytosolic Cu/Zn-superoxide dismutase, peroxidase isozymes 1 and 2, and catalase were observed after at 48 h of oxyfluorfen treatment in the wild-type. Non-enzymatic antioxidants appeared to respond faster to oxyfluorfen-induced photodynamic stress than did enzymatic antioxidants. Protective responses for the detoxification of active oxygen species were induced to counteract photodynamic stress in oxyfluorfen-treated, wild-type plants. However, oxyfluorfen-treated, transgenic plants suffered less oxidative stress, confirming increased herbicidal resistance resulted from dual expression of M. xanthus Protox in chloroplasts and mitochondria. PMID:15890521

  7. Regulation of expression of the pilA gene in Myxococcus xanthus.

    PubMed Central

    Wu, S S; Kaiser, D

    1997-01-01

    Type IV pili are required for social gliding motility in Myxococcus xanthus. In this work, the expression of pilin (the pilA gene product) during vegetative growth and fruiting-body development was examined. A polyclonal antibody against the pilA gene product (prepilin) was prepared, along with a pilA-lacZ fusion, and was used to assay expression of pilA in M. xanthus in different mutant backgrounds. pilA expression required the response regulator pilR but was negatively regulated by the putative sensor kinase pilS. pilA expression did not require pilB, pilC, or pilT. pilA was also autoregulated; a mutation which altered an invariant glutamate five residues from the presumed prepilin processing site eliminated this autoregulation, as did a deletion of the pilA gene. Primer extension and S1 nuclease analysis identified a sigma54 promoter upstream of pilA, consistent with the homology of pilR to the NtrC family of response regulators. Expression of pilA was found to be developmentally regulated; however, the timing of this expression pattern was not entirely dependent on pilS or pilR. Finally, pilA expression was induced by high nutrient concentrations, an effect that was also not dependent on pilS or pilR. PMID:9401034

  8. An Adenylyl Cyclase, CyaA, of Myxococcus xanthus Functions in Signal Transduction during Osmotic Stress

    PubMed Central

    Kimura, Yoshio; Mishima, Yukako; Nakano, Hiromi; Takegawa, Kaoru

    2002-01-01

    An adenylyl cyclase gene (cyaA) present upstream of an osmosensor protein gene (mokA) was isolated from Myxococcus xanthus. cyaA encoded a polypeptide of 843 amino acids with a predicted molecular mass of 91,187 Da. The predicted cyaA gene product had structural similarity to the receptor-type adenylyl cyclases that are composed of an amino-terminal sensor domain and a carboxy-terminal catalytic domain of adenylyl cyclase. In reverse transcriptase PCR experiments, the transcript of the cyaA gene was detected mainly during development and spore germination. A cyaA mutant, generated by gene disruption, showed normal growth, development, and germination. However, a cyaA mutant placed under conditions of ionic (NaCl) or nonionic (sucrose) osmostress exhibited a marked reduction in spore formation and spore germination. When wild-type and cyaA mutant cells at developmental stages were stimulated with 0.2 M NaCl or sucrose, the mutant cells increased cyclic AMP accumulation at levels similar to those of the wild-type cells. In contrast, the mutant cells during spore germination had mainly lost the ability to respond to high-ionic osmolarity. In vegetative cells, the cyaA mutant responded normally to osmotic stress. These results suggested that M. xanthus CyaA functions mainly as an ionic osmosensor during spore germination and that CyaA is also required for osmotic tolerance in fruiting formation and sporulation. PMID:12057952

  9. Structural Insights into RNA Polymerase Recognition and Essential Function of Myxococcus xanthus CdnL

    PubMed Central

    Gallego-García, Aránzazu; Mirassou, Yasmina; García-Moreno, Diana; Elías-Arnanz, Montserrat; Jiménez, María Angeles; Padmanabhan, S.

    2014-01-01

    CdnL and CarD are two functionally distinct members of the CarD_CdnL_TRCF family of bacterial RNA polymerase (RNAP)-interacting proteins, which co-exist in Myxococcus xanthus. While CarD, found exclusively in myxobacteria, has been implicated in the activity of various extracytoplasmic function (ECF) σ-factors, the function and mode of action of the essential CdnL, whose homologs are widespread among bacteria, remain to be elucidated in M. xanthus. Here, we report the NMR solution structure of CdnL and present a structure-based mutational analysis of its function. An N-terminal five-stranded β-sheet Tudor-like module in the two-domain CdnL mediates binding to RNAP-β, and mutations that disrupt this interaction impair cell growth. The compact CdnL C-terminal domain consists of five α-helices folded as in some tetratricopeptide repeat-like protein-protein interaction domains, and contains a patch of solvent-exposed nonpolar and basic residues, among which a set of basic residues is shown to be crucial for CdnL function. We show that CdnL, but not its loss-of-function mutants, stabilizes formation of transcriptionally competent, open complexes by the primary σA-RNAP holoenzyme at an rRNA promoter in vitro. Consistent with this, CdnL is present at rRNA promoters in vivo. Implication of CdnL in RNAP-σA activity and of CarD in ECF-σ function in M. xanthus exemplifies how two related members within a widespread bacterial protein family have evolved to enable distinct σ-dependent promoter activity. PMID:25272012

  10. Structural insights into RNA polymerase recognition and essential function of Myxococcus xanthus CdnL.

    PubMed

    Gallego-García, Aránzazu; Mirassou, Yasmina; García-Moreno, Diana; Elías-Arnanz, Montserrat; Jiménez, María Angeles; Padmanabhan, S

    2014-01-01

    CdnL and CarD are two functionally distinct members of the CarD_CdnL_TRCF family of bacterial RNA polymerase (RNAP)-interacting proteins, which co-exist in Myxococcus xanthus. While CarD, found exclusively in myxobacteria, has been implicated in the activity of various extracytoplasmic function (ECF) σ-factors, the function and mode of action of the essential CdnL, whose homologs are widespread among bacteria, remain to be elucidated in M. xanthus. Here, we report the NMR solution structure of CdnL and present a structure-based mutational analysis of its function. An N-terminal five-stranded β-sheet Tudor-like module in the two-domain CdnL mediates binding to RNAP-β, and mutations that disrupt this interaction impair cell growth. The compact CdnL C-terminal domain consists of five α-helices folded as in some tetratricopeptide repeat-like protein-protein interaction domains, and contains a patch of solvent-exposed nonpolar and basic residues, among which a set of basic residues is shown to be crucial for CdnL function. We show that CdnL, but not its loss-of-function mutants, stabilizes formation of transcriptionally competent, open complexes by the primary σA-RNAP holoenzyme at an rRNA promoter in vitro. Consistent with this, CdnL is present at rRNA promoters in vivo. Implication of CdnL in RNAP-σA activity and of CarD in ECF-σ function in M. xanthus exemplifies how two related members within a widespread bacterial protein family have evolved to enable distinct σ-dependent promoter activity. PMID:25272012

  11. Tracking of Chromosome and Replisome Dynamics in Myxococcus xanthus Reveals a Novel Chromosome Arrangement

    PubMed Central

    Schumacher, Dominik; Søgaard-Andersen, Lotte

    2013-01-01

    Cells closely coordinate cell division with chromosome replication and segregation; however, the mechanisms responsible for this coordination still remain largely unknown. Here, we analyzed the spatial arrangement and temporal dynamics of the 9.1 Mb circular chromosome in the rod-shaped cells of Myxococcus xanthus. For chromosome segregation, M. xanthus uses a parABS system, which is essential, and lack of ParB results in chromosome segregation defects as well as cell divisions over nucleoids and the formation of anucleate cells. From the determination of the dynamic subcellular location of six genetic loci, we conclude that in newborn cells ori, as monitored following the ParB/parS complex, and ter regions are localized in the subpolar regions of the old and new cell pole, respectively and each separated from the nearest pole by approximately 1 µm. The bulk of the chromosome is arranged between the two subpolar regions, thus leaving the two large subpolar regions devoid of DNA. Upon replication, one ori region remains in the original subpolar region while the second copy segregates unidirectionally to the opposite subpolar region followed by the rest of the chromosome. In parallel, the ter region of the mother chromosome relocates, most likely passively, to midcell, where it is replicated. Consequently, after completion of replication and segregation, the two chromosomes show an ori-ter-ter-ori arrangement with mirror symmetry about a transverse axis at midcell. Upon completion of segregation of the ParB/parS complex, ParA localizes in large patches in the DNA-free subpolar regions. Using an Ssb-YFP fusion as a proxy for replisome localization, we observed that the two replisomes track independently of each other from a subpolar region towards ter. We conclude that M. xanthus chromosome arrangement and dynamics combine features from previously described systems with new features leading to a novel spatiotemporal arrangement pattern. PMID:24068967

  12. Neutral and Phospholipids of the Myxococcus xanthus Lipodome during Fruiting Body Formation and Germination

    PubMed Central

    Ahrendt, Tilman; Wolff, Hendrik

    2015-01-01

    Myxobacteria are well-known for their complex life cycle, including the formation of spore-filled fruiting bodies. The model organism Myxococcus xanthus exhibits a highly complex composition of neutral and phospholipids, including triacylglycerols (TAGs), diacylglycerols (DAGs), phosphatidylethanolamines (PEs), phosphatidylglycerols (PGs), cardiolipins (CLs), and sphingolipids, including ceramides (Cers) and ceramide phosphoinositols (Cer-PIs). In addition, ether lipids have been shown to be involved in development and signaling. In this work, we describe the lipid profile of M. xanthus during its entire life cycle, including spore germination. PEs, representing one of the major components of the bacterial membrane, decreased by about 85% during development from vegetative rods to round myxospores, while TAGs first accumulated up to 2-fold before they declined 48 h after the induction of sporulation. Presumably, membrane lipids are incorporated into TAG-containing lipid bodies, serving as an intermediary energy source for myxospore formation. The ceramides Cer(d-19:0/iso-17:0) and Cer(d-19:0/16:0) accumulated 6-fold and 3-fold, respectively, after 24 h of development, identifying them to be novel putative biomarkers for M. xanthus sporulation. The most abundant ether lipid, 1-iso-15:0-alkyl-2,3-di-iso-15:0-acyl glycerol (TG1), exhibited a lipid profile different from that of all TAGs during sporulation, reinforcing its signaling character. The absence of all these lipid profile changes in mutants during development supports the importance of lipids in myxobacterial development. During germination of myxospores, only the de novo biosynthesis of new cell membrane fatty acids was observed. The unexpected accumulation of TAGs also during germination might indicate a function of TAGs as intermediary storage lipids during this part of the life cycle as well. PMID:26162876

  13. GidA is an FAD-binding protein involved in development of Myxococcus xanthus.

    PubMed

    White, D J; Merod, R; Thomasson, B; Hartzell, P L

    2001-10-01

    A gene encoding a homologue of the Escherichia coli GidA protein (glucose-inhibited division protein A) lies immediately upstream of aglU, a gene encoding a WD-repeat protein required for motility and development in Myxococcus xanthus. The GidA protein of M. xanthus shares about 48% identity overall with the small (approximately equal to 450 amino acid) form of GidA from eubacteria and about 24% identity overall with the large (approximately equal to 620 amino acid) form of GidA from eubacteria and eukaryotes. Each of these proteins has a conserved dinucleotide-binding motif at the N-terminus. To determine if GidA binds dinucleotide, the M. xanthus gene was expressed with a His6 tag in E. coli cells. Purified rGidA is a yellow protein that absorbs maximally at 374 and 450 nm, consistent with FAD or FMN. Thin-layer chromatography (TLC) showed that rGidA contains an FAD cofactor. Fractionation and immunocytochemical localization show that full length GidA protein is present in the cytoplasm and transported to the periplasm of vegetative-grown M. xanthus cells. In cells that have been starved for nutrients, GidA is found in the cytoplasm. Although GidA lacks an obvious signal sequence, it contains a twin arginine transport (Tat) motif, which is conserved among proteins that bind cofactors in the cytoplasm and are transported to the periplasm as folded proteins. To determine if GidA, like AglU, is involved in motility and development, the gidA gene was disrupted. The gidA- mutant has wild-type gliding motility and initially is able to form fruiting bodies like the wild type when starved for nutrients. However, after several generations, a stable derivative arises, gidA*, which is indistinguishable from the gidA- parent on vegetative medium, but is no longer able to form fruiting bodies. The gidA* mutant releases a heat-stable, protease-resistant, small molecular weight molecule that acts in trans to inhibit aggregation and gene expression of wild-type cells during

  14. Regulation of a Protein Acetyltransferase in Myxococcus xanthus by the Coenzyme NADP+

    PubMed Central

    Liu, Xin-Xin

    2015-01-01

    ABSTRACT NADP+ is a vital cofactor involved in a wide variety of activities, such as redox potential and cell death. Here, we show that NADP+ negatively regulates an acetyltransferase from Myxococcus xanthus, Mxan_3215 (MxKat), at physiologic concentrations. MxKat possesses an NAD(P)-binding domain fused to the Gcn5-type N-acetyltransferase (GNAT) domain. We used isothermal titration calorimetry (ITC) and a coupled enzyme assay to show that NADP+ bound to MxKat and that the binding had strong effects on enzyme activity. The Gly11 residue of MxKat was confirmed to play an important role in NADP+ binding using site-directed mutagenesis and circular dichroism spectrometry. In addition, using mass spectrometry, site-directed mutagenesis, and a coupling enzymatic assay, we demonstrated that MxKat acetylates acetyl coenzyme A (acetyl-CoA) synthetase (Mxan_2570) at Lys622 in response to changes in NADP+ concentration. Collectively, our results uncovered a mechanism of protein acetyltransferase regulation by the coenzyme NADP+ at physiological concentrations, suggesting a novel signaling pathway for the regulation of cellular protein acetylation. IMPORTANCE Microorganisms have developed various protein posttranslational modifications (PTMs), which enable cells to respond quickly to changes in the intracellular and extracellular milieus. This work provides the first biochemical characterization of a protein acetyltransferase (MxKat) that contains a fusion between a GNAT domain and NADP+-binding domain with Rossmann folds, and it demonstrates a novel signaling pathway for regulating cellular protein acetylation in M. xanthus. We found that NADP+ specifically binds to the Rossmann fold of MxKat and negatively regulates its acetyltransferase activity. This finding provides novel insight for connecting cellular metabolic status (NADP+ metabolism) with levels of protein acetylation, and it extends our understanding of the regulatory mechanisms underlying PTMs. PMID:26598367

  15. Intra- and Interprotein Phosphorylation between Two-hybrid Histidine Kinases Controls Myxococcus xanthus Developmental Progression*

    PubMed Central

    Schramm, Andreas; Lee, Bongsoo; Higgs, Penelope I.

    2012-01-01

    Histidine-aspartate phosphorelay signaling systems are used to couple stimuli to cellular responses. A hallmark feature is the highly modular signal transmission modules that can form both simple “two-component” systems and sophisticated multicomponent systems that integrate stimuli over time and space to generate coordinated and fine-tuned responses. The deltaproteobacterium Myxococcus xanthus contains a large repertoire of signaling proteins, many of which regulate its multicellular developmental program. Here, we assign an orphan hybrid histidine protein kinase, EspC, to the Esp signaling system that negatively regulates progression through the M. xanthus developmental program. The Esp signal system consists of the hybrid histidine protein kinase, EspA, two serine/threonine protein kinases, and a putative transport protein. We demonstrate that EspC is an essential component of this system because ΔespA, ΔespC, and ΔespA ΔespC double mutants share an identical developmental phenotype. Neither substitution of the phosphoaccepting histidine residue nor deletion of the entire catalytic ATPase domain in EspC produces an in vivo mutant developmental phenotype. In contrast, substitution of the receiver phosphoaccepting residue yields the null phenotype. Although the EspC histidine kinase can efficiently autophosphorylate in vitro, it does not act as a phosphodonor to its own receiver domain. Our in vitro and in vivo analyses suggest the phosphodonor is instead the EspA histidine kinase. We propose EspA and EspC participate in a novel hybrid histidine protein kinase signaling mechanism involving both inter- and intraprotein phosphotransfer. The output of this signaling system appears to be the combined phosphorylated state of the EspA and EspC receiver modules. This system regulates the proteolytic turnover of MrpC, an important regulator of the developmental program. PMID:22661709

  16. MasABK Proteins Interact with Proteins of the Type IV Pilin System to Affect Social Motility of Myxococcus xanthus

    PubMed Central

    Fremgen, Sarah; Williams, Amanda; Furusawa, Gou; Dziewanowska, Katarzyna; Settles, Matthew; Hartzell, Patricia

    2013-01-01

    Gliding motility is critical for normal development of spore-filled fruiting bodies in the soil bacterium Myxococcus xanthus. Mutations in mgl block motility and development but one mgl allele can be suppressed by a mutation in masK, the last gene in an operon adjacent to the mgl operon. Deletion of the entire 5.5 kb masABK operon crippled gliding and fruiting body development and decreased sporulation. Expression of pilAGHI, which encodes type IV pili (TFP) components essential for social (S) gliding, several cryptic pil genes, and a LuxR family protein were reduced significantly in the Δmas mutant while expression of the myxalamide operon was increased significantly. Localization and two-hybrid analysis suggest that the three Mas proteins form a membrane complex. MasA-PhoA fusions confirmed that MasA is an integral cytoplasmic membrane protein with a ≈100 amino acid periplasmic domain. Results from yeast two-hybrid assays showed that MasA interacts with the lipoprotein MasB and MasK, a protein kinase and that MasB and MasK interact with one another. Additionally, yeast two-hybrid analysis revealed a physical interaction between two gene products of the mas operon, MasA and MasB, and PilA. Deletion of mas may be accompanied by compensatory mutations since complementation of the Δmas social gliding and developmental defects required addition of both pilA and masABK. PMID:23342171

  17. Outside-In Assembly Pathway of the Type IV Pilus System in Myxococcus xanthus

    PubMed Central

    Friedrich, Carmen; Bulyha, Iryna

    2014-01-01

    Type IV pili (T4P) are ubiquitous bacterial cell surface structures that undergo cycles of extension, adhesion, and retraction. T4P function depends on a highly conserved envelope-spanning macromolecular machinery consisting of 10 proteins that localizes polarly in Myxococcus xanthus. Using this localization, we investigated the entire T4P machinery assembly pathway by systematically profiling the stability of all and the localization of eight of these proteins in the absence of other T4P machinery proteins as well as by mapping direct protein-protein interactions. Our experiments uncovered a sequential, outside-in pathway starting with the outer membrane (OM) PilQ secretin ring. PilQ recruits a subcomplex consisting of the inner membrane (IM) lipoprotein PilP and the integral IM proteins PilN and PilO by direct interaction with the periplasmic domain of PilP. The PilP/PilN/PilO subcomplex recruits the cytoplasmic PilM protein, by direct interaction between PilN and PilM, and the integral IM protein PilC. The PilB/PilT ATPases that power extension/retraction localize independently of other T4P machinery proteins. Thus, assembly of the T4P machinery initiates with formation of the OM secretin ring and continues inwards over the periplasm and IM to the cytoplasm. PMID:24187092

  18. The Myxococcus xanthus dsg gene product performs functions of translation initiation factor IF3 in vivo.

    PubMed Central

    Kalman, L V; Cheng, Y L; Kaiser, D

    1994-01-01

    The amino acid sequence of the Dsg protein is 50% identical to that of translation initiation factor IF3 of Escherichia coli, the product of its infC gene. Anti-E. coli IF3 antibodies cross-react with the Dsg protein. Tn5 insertion mutations in dsg are lethal. When ample nutrients are available, however, certain dsg point mutant strains grow at the same rate as wild-type cells. Under the starvation conditions that induce fruiting body development, these dsg mutants begin to aggregate but fail to develop further. The level of Dsg antigen, as a fraction of total cell protein, does not change detectably during growth and development, as expected for a factor essential for protein synthesis. The amount of IF3 protein in E. coli is known to be autoregulated at the translational level. This autoregulation is lost in an E. coli infC362 missense mutant. The dsg+ gene from Myxococcus xanthus restores normal autoregulation to the infC362 mutant strain. Dsg is distinguished from IF3 of E. coli, other enteric bacteria, and Bacillus stearothermophilus by having a C-terminal tail of 66 amino acids. Partial and complete deletion of this tail showed that it is needed for certain vegetative and developmental functions but not for viability. Images PMID:8113185

  19. Nutrition of Myxococcus xanthus FBa and some of its auxotrophic mutants.

    PubMed

    Hemphill, H E; Zahler, S A

    1968-03-01

    A defined medium containing 15 amino acids plus salts was used to study the nutrition of Myxococcus xanthus FBa. The amino acids phenylalanine, leucine, isoleucine, valine, and methionine were essential for growth, whereas glycine, proline, asparagine, alanine, lysine, and threonine stimulated growth. An unusual pattern of requirement was found in the aromatic amino acids. Phenylalanine was essential and served as the precursor of tyrosine. Growth in the absence of tryptophan was adaptive, with cells reaching a growth rate equal to that of controls after a lag of about a week. (14)C-labeled ribose and glucose were not appreciably metabolized. Auxotrophs requiring purines and pyrimidines were isolated and were used to study the fate of externally supplied nucleic acid derivatives. Appropriate mutants could satisfy their requirements with free bases, nucleosides, and nucleotides, and could hydrolyze nucleic acids and use the products. However, studies using (14)C-ribose-labeled uridine (isolated from a Salmonella typhimurium pyrimidine auxotroph) showed that externally supplied nucleic acid derivatives were incorporated almost solely into the nucleic acids of the myxobacters, with little used either for energy-yielding oxidations or other cell anabolism. PMID:4868349

  20. Transmission of a signal that synchronizes cell movements in swarms of Myxococcus xanthus

    PubMed Central

    Kaiser, Dale; Warrick, Hans

    2014-01-01

    We offer evidence for a signal that synchronizes the behavior of hundreds of Myxococcus xanthus cells in a growing swarm. Swarms are driven to expand by the periodic reversing of direction by members. By using time-lapse photomicroscopy, two organized multicellular elements of the swarm were analyzed: single-layered, rectangular rafts and round, multilayered mounds. Rafts of hundreds of cells with their long axes aligned in parallel enlarge as individual cells from the neighborhood join them from either side. Rafts can also add a second layer piece by piece. By repeating layer additions to a raft and rounding each layer, a regular multilayered mound can be formed. About an hour after a five-layered mound had formed, all of the cells from its top layer descended to the periphery of the fourth layer, both rapidly and synchronously. Following the first synchronized descent and spaced at constant time intervals, a new fifth layer was (re)constructed from fourth-layer cells, in very close proximity to its old position and with a number of cells similar to that before the “explosive” descent. This unexpected series of changes in mound structure can be explained by the spread of a signal that synchronizes the reversals of large groups of individual cells. PMID:25149859

  1. Crystal Structure of Protoporphyrinogen Oxidase from Myxococcus Xanthus and its Complex with the Inhibitor Acifluorfen*

    PubMed Central

    Corradi, Hazel R.; Corrigall, Anne V.; Boix, Ester; Mohan, C. Gopi; Sturrock, Edward D.; Meissner, Peter N.; Acharya, K. Ravi

    2007-01-01

    Protoporphyrinogen IX oxidase, a monotopic membrane protein, which catalyzes the oxidation of protoporphyrinogen IX to protoporphyrin IX in the heme/chlorophyll biosynthetic pathway, is distributed widely throughout nature. Here we present the structure of protoporphyrinogen IX oxidase from Myxococcus xanthus, an enzyme with similar catalytic properties to human protoporphyrinogen IX oxidase that also binds the common plant herbicide, acifluorfen. In the native structure, the planar porphyrinogen substrate is mimicked by a Tween 20 molecule, tracing three sides of the macrocycle. In contrast, acifluorfen does not mimic the planarity of the substrate but is accommodated by the shape of the binding pocket and held in place by electrostatic and aromatic interactions. A hydrophobic patch surrounded by positively charged residues suggests the position of the membrane anchor, differing from the one proposed for the tobacco mitochondrial protoporphyrinogen oxidase. Interestingly, there is a discrepancy between the dimerization state of the protein in solution and in the crystal. Conserved structural features are discussed in relation to a number of South African variegate porphyria-causing mutations in the human enzyme. PMID:17046834

  2. Pattern formation by a cell surface-associated morphogen in Myxococcus xanthus

    PubMed Central

    Jelsbak, Lars; Søgaard-Andersen, Lotte

    2002-01-01

    In response to starvation, an unstructured population of identical Myxococcus xanthus cells rearranges into an asymmetric, stable pattern of multicellular fruiting bodies. Central to this pattern formation process are changes in organized cell movements from swarming to aggregation. Aggregation is induced by the cell surface-associated C-signal. To understand how aggregation is accomplished, we have analyzed how C-signal modulates cell behavior. We show that C-signal induces a motility response that includes increases in transient gliding speeds and in the duration of gliding intervals and decreases in stop and reversal frequencies. This response results in a switch in cell behavior from an oscillatory to a unidirectional type of behavior in which the net-distance traveled by a cell per minute is increased. We propose that the C-signal-dependent regulation of the reversal frequency is essential for aggregation and that the remaining C-signal-dependent changes in motility parameters contribute to aggregation by increasing the net-distance traveled by starving cells per minute. In our model for symmetry-breaking and aggregation, C-signal transmission is a local event involving direct contacts between cells that results in a global organization of cells. This pattern formation mechanism does not require a diffusible substance or other actions at a distance. Rather it depends on contact-induced changes in motility behavior to direct cells appropriately PMID:11842199

  3. Disruption of aldA Influences the Developmental Process in Myxococcus xanthus

    PubMed Central

    Ward, Mandy J.; Lew, Helen; Zusman, David R.

    2000-01-01

    Previously, we identified a gene (aldA) from Myxococcus xanthus, which we suggested encoded the enzyme alanine dehydrogenase on the basis of similarity to known Ald protein sequences (M. J. Ward, H. Lew, A. Treuner-Lange, and D. R. Zusman, J. Bacteriol. 180:5668–5675, 1998). In this study, we have confirmed that aldA does encode a functional alanine dehydrogenase, since it catalyzes the reversible conversion of alanine to pyruvate and ammonia. Whereas an aldA gene disruption mutation did not significantly influence the rate of growth or spreading on a rich medium, AldA was required for growth on a minimal medium containing l-alanine as the major source of carbon. Under developmental conditions, the aldA mutation caused delayed aggregation in both wild-type (DZ2) and FB (DZF1) strains. Poorly formed aggregates and reduced levels of spores were apparent in the DZ2 aldA mutant, even after prolonged development. PMID:10629210

  4. Synthesis of several membrane proteins during developmental aggregation in Myxococcus xanthus.

    PubMed

    Orndorff, P E; Dworkin, M

    1982-01-01

    We have examined the pattern of synthesis of several membrane proteins during the aggregation phase of development in Myxococcus xanthus. Development was initiated by plating vegetative cells on polycarbonate filters placed on top of an agar medium that supported fruiting body formation. At various times during aggregation a filter was removed, the cells were pulse-labeled with [35S]methionine, and the membrane proteins were separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The rate of synthesis of numerous individual proteins changed during aggregation; we concentrated on six whose pattern of synthesis was greatly altered during aggregation. The rate of synthesis of five of the six proteins increased considerably during aggregation; that of the remaining protein was curtailed and appeared to be regulated by nutrient conditions. Three of the five major membrane proteins that increased during aggregation had a unique pattern of synthesis that was displayed only under conditions that are are required for development - high cell density, nutrient depletion, and a solid (agar) surface. The remaining two proteins were not unique to development; the appearance of one protein could be induced under conditions of high cell density, whereas the other could be induced by placing the cells on a solid agar surface. All of the five major proteins that appeared during development did so during the preaggregation stage, and the synthesis of four of the five proteins appeared to be curtailed late in aggregation. The synthesis of the remaining protein continued throughout aggregation. PMID:6798022

  5. Myxococcus xanthus mokA Encodes a Histidine Kinase-Response Regulator Hybrid Sensor Required for Development and Osmotic Tolerance

    PubMed Central

    Kimura, Yoshio; Nakano, Hiromi; Terasaka, Hideaki; Takegawa, Kaoru

    2001-01-01

    A gene, mokA, encoding a protein with similarities to histidine kinase-response regulator hybrid sensor, was cloned from a Myxococcus xanthus genomic library. The predicted mokA gene product was found to contain three domains: an amino-terminal input domain, a central transmitter domain, and a carboxy-terminal receiver domain. mokA mutants placed under starvation conditions exhibited reduced sporulation. Mutation of mokA also caused marked growth retardation at high osmolarity. These results indicated that M. xanthus MokA is likely a transmembrane sensor that is required for development and osmotic tolerance. The putative function of MokA is similar to that of the hybrid histidine kinase, DokA, of the eukaryotic slime mold Dictyostelium discoideum. PMID:11157925

  6. Synthesis and Assembly of a Novel Glycan Layer in Myxococcus xanthus Spores*

    PubMed Central

    Holkenbrink, Carina; Hoiczyk, Egbert; Kahnt, Jörg; Higgs, Penelope I.

    2014-01-01

    Myxococcus xanthus is a Gram-negative deltaproteobacterium that has evolved the ability to differentiate into metabolically quiescent spores that are resistant to heat and desiccation. An essential feature of the differentiation processes is the assembly of a rigid, cell wall-like spore coat on the surface of the outer membrane. In this study, we characterize the spore coat composition and describe the machinery necessary for secretion of spore coat material and its subsequent assembly into a stress-bearing matrix. Chemical analyses of isolated spore coat material indicate that the spore coat consists primarily of short 1–4- and 1–3-linked GalNAc polymers that lack significant glycosidic branching and may be connected by glycine peptides. We show that 1–4-linked glucose (Glc) is likely a minor component of the spore coat with the majority of the Glc arising from contamination with extracellular polysaccharides, O-antigen, or storage compounds. Neither of these structures is required for the formation of resistant spores. Our analyses indicate the GalNAc/Glc polymer and glycine are exported by the ExoA-I system, a Wzy-like polysaccharide synthesis and export machinery. Arrangement of the capsular-like polysaccharides into a rigid spore coat requires the NfsA–H proteins, members of which reside in either the cytoplasmic membrane (NfsD, -E, and -G) or outer membrane (NfsA, -B, and -C). The Nfs proteins function together to modulate the chain length of the surface polysaccharides, which is apparently necessary for their assembly into a stress-bearing matrix. PMID:25271164

  7. Colony Expansion of Socially Motile Myxococcus xanthus Cells Is Driven by Growth, Motility, and Exopolysaccharide Production

    PubMed Central

    Patra, Pintu; Kissoon, Kimberley; Cornejo, Isabel; Kaplan, Heidi B.; Igoshin, Oleg A.

    2016-01-01

    Myxococcus xanthus, a model organism for studies of multicellular behavior in bacteria, moves exclusively on solid surfaces using two distinct but coordinated motility mechanisms. One of these, social (S) motility is powered by the extension and retraction of type IV pili and requires the presence of exopolysaccharides (EPS) produced by neighboring cells. As a result, S motility requires close cell-to-cell proximity and isolated cells do not translocate. Previous studies measuring S motility by observing the colony expansion of cells deposited on agar have shown that the expansion rate increases with initial cell density, but the biophysical mechanisms involved remain largely unknown. To understand the dynamics of S motility-driven colony expansion, we developed a reaction-diffusion model describing the effects of cell density, EPS deposition and nutrient exposure on the expansion rate. Our results show that at steady state the population expands as a traveling wave with a speed determined by the interplay of cell motility and growth, a well-known characteristic of Fisher’s equation. The model explains the density-dependence of the colony expansion by demonstrating the presence of a lag phase–a transient period of very slow expansion with a duration dependent on the initial cell density. We propose that at a low initial density, more time is required for the cells to accumulate enough EPS to activate S-motility resulting in a longer lag period. Furthermore, our model makes the novel prediction that following the lag phase the population expands at a constant rate independent of the cell density. These predictions were confirmed by S motility experiments capturing long-term expansion dynamics. PMID:27362260

  8. Comparative genomics of transport proteins in developmental bacteria: Myxococcus xanthus and Streptomyces coelicolor

    PubMed Central

    2013-01-01

    Background Two of the largest fully sequenced prokaryotic genomes are those of the actinobacterium, Streptomyces coelicolor (Sco), and the δ-proteobacterium, Myxococcus xanthus (Mxa), both differentiating, sporulating, antibiotic producing, soil microbes. Although the genomes of Sco and Mxa are the same size (~9 Mbp), Sco has 10% more genes that are on average 10% smaller than those in Mxa. Results Surprisingly, Sco has 93% more identifiable transport proteins than Mxa. This is because Sco has amplified several specific types of its transport protein genes, while Mxa has done so to a much lesser extent. Amplification is substrate- and family-specific. For example, Sco but not Mxa has amplified its voltage-gated ion channels but not its aquaporins and mechano-sensitive channels. Sco but not Mxa has also amplified drug efflux pumps of the DHA2 Family of the Major Facilitator Superfamily (MFS) (49 versus 6), amino acid transporters of the APC Family (17 versus 2), ABC-type sugar transport proteins (85 versus 6), and organic anion transporters of several families. Sco has not amplified most other types of transporters. Mxa has selectively amplified one family of macrolid exporters relative to Sco (16 versus 1), consistent with the observation that Mxa makes more macrolids than does Sco. Conclusions Except for electron transport carriers, there is a poor correlation between the types of transporters found in these two organisms, suggesting that their solutions to differentiative and metabolic needs evolved independently. A number of unexpected and surprising observations are presented, and predictions are made regarding the physiological functions of recognizable transporters as well as the existence of yet to be discovered transport systems in these two important model organisms and their relatives. The results provide insight into the evolutionary processes by which two dissimilar prokaryotes evolved complexity, particularly through selective chromosomal gene

  9. The clpB gene is involved in the stress response of Myxococcus xanthus during vegetative growth and development

    PubMed Central

    Pan, Hongwei; Luan, Jia; He, Xuesong; Lux, Renate

    2012-01-01

    The Clp/HSP100 family of molecular chaperones is ubiquitous in both prokaryotes and eukaryotes. These proteins play important roles in refolding, disaggregating and degrading proteins damaged by stress. As a subclass of the Clp/HSP100 family, ClpB has been shown to be involved in various stress responses as well as other functions in bacteria. In the present study, we investigated the role of a predicted ClpB-encoding gene, MXAN5092, in the stress response during vegetative growth and development of Myxococcus xanthus. Transcriptional analysis confirmed induction of this clpB homologue under different stress conditions, and further phenotypic analysis revealed that an in-frame deletion mutant of MXAN5092 was more sensitive to various stress treatments than the wild-type strain during vegetative growth. Moreover, the absence of the MXAN5092 gene resulted in decreased heat tolerance of myxospores, indicating the involvement of this clpB homologue in the stress response during the development of myxospores. The M. xanthus recombinant ClpB (MXAN5092) protein also showed a general chaperone activity in vitro. Overall, our genetic and phenotypic analysis of the predicted ATP-dependent chaperone protein ClpB (MXAN5092) demonstrated that it functions as a chaperone protein and plays an important role in cellular stress tolerance during both vegetative growth and development of M. xanthus. PMID:22790397

  10. BacM, an N-terminally processed bactofilin of Myxococcus xanthus, is crucial for proper cell shape

    PubMed Central

    Koch, Matthias K.; McHugh, Colleen A.; Hoiczyk, Egbert

    2011-01-01

    Summary Bactofilins are fibre-forming bacterial cytoskeletal proteins. Here, we report the structural and biochemical characterization of MXAN_7475 (BacM), one of the four bactofilins of Myxococcus xanthus. Absence of BacM leads to a characteristic ‘crooked’ cell morphology and an increased sensitivity to antibiotics targeting cell wall biosynthesis. The absence of the other three bactofilins MXAN_4637–4635 (BacN-P) has no obvious phenotype. In M. xanthus, BacM exists as a 150-amino-acid full-length version and as a version cleaved before Ser28. In the cell, native BacM forms 3 nm wide fibres, which assemble into bundles forming helix-like cytoplasmic cables throughout the cell, and in a subset of cells additionally a polarly arranged lateral rod-like structure. Isolated fibres consist almost completely of the N-terminally truncated version, suggesting that the proteolytic cleavage occurs before or during fibre formation. Fusion of BacM to mCherry perturbs BacM function and cellular fibre arrangement, resulting for example in the formation of one prominent polar corkscrew-like structure per cell. Immunofluorescence staining of BacM and MreB shows that their cellular distributions are not matching. Taken together, these data suggest that rod-shaped bacteria like M. xanthus use bactofilin fibres to achieve and maintain their characteristic cell morphology and cell wall stability. PMID:21414039

  11. BacM, an N-terminally processed bactofilin of Myxococcus xanthus, is crucial for proper cell shape.

    PubMed

    Koch, Matthias K; McHugh, Colleen A; Hoiczyk, Egbert

    2011-05-01

    Bactofilins are fibre-forming bacterial cytoskeletal proteins. Here, we report the structural and biochemical characterization of MXAN_7475 (BacM), one of the four bactofilins of Myxococcus xanthus. Absence of BacM leads to a characteristic 'crooked' cell morphology and an increased sensitivity to antibiotics targeting cell wall biosynthesis. The absence of the other three bactofilins MXAN_4637-4635 (BacN-P) has no obvious phenotype. In M. xanthus, BacM exists as a 150-amino-acid full-length version and as a version cleaved before Ser28. In the cell, native BacM forms 3 nm wide fibres, which assemble into bundles forming helix-like cytoplasmic cables throughout the cell, and in a subset of cells additionally a polarly arranged lateral rod-like structure. Isolated fibres consist almost completely of the N-terminally truncated version, suggesting that the proteolytic cleavage occurs before or during fibre formation. Fusion of BacM to mCherry perturbs BacM function and cellular fibre arrangement, resulting for example in the formation of one prominent polar corkscrew-like structure per cell. Immunofluorescence staining of BacM and MreB shows that their cellular distributions are not matching. Taken together, these data suggest that rod-shaped bacteria like M. xanthus use bactofilin fibres to achieve and maintain their characteristic cell morphology and cell wall stability. PMID:21414039

  12. Effects of site-directed mutagenesis of mglA on motility and swarming of Myxococcus xanthus

    PubMed Central

    2010-01-01

    Background The mglA gene from the bacterium Myxococcus xanthus encodes a 22kDa protein related to the Ras superfamily of monomeric GTPases. MglA is required for the normal function of A-motility (adventurous), S-motility (social), fruiting body morphogenesis, and sporulation. MglA and its homologs differ from all eukaryotic and other prokaryotic GTPases because they have a threonine (Thr78) in place of the highly conserved aspartate residue of the consensus PM3 (phosphate-magnesium binding) region. To identify residues critical for MglA function or potential protein interactions, and explore the function of Thr78, the phenotypes of 18 mglA mutants were characterized. Results Nine mutants, with mutations predicted to alter residues that bind the guanine base or coordinate magnesium, did not produce detectable MglA. As expected, these mutants were mot- dev- because MglA is essential for these processes. Of the remaining nine mutants, seven showed a wild-type distribution pattern for MglA but fell into two categories with regard to function. Five of the seven mutants exhibited mild phenotypes, but two mutants, T78D and P80A, abolished motility and development. The localization pattern of MglA was abolished in two mutants that were mot- spo- and dev-. These two mutants were predicted to alter surface residues at Asp52 and Thr54, which suggests that these residues are critical for proper localization and may define a protein interaction site. Improving the consensus match with Ras at Thr78 abolished function of MglA. Only the conservative serine substitution was tolerated at this position. Merodiploid constructs revealed that a subset of alleles, including mglAD52A, were dominant and also illustrated that changing the balance of MglA and its co-transcribed partner, MglB, affects A-motility. Conclusion Our results suggest that GTP binding is critical for stability of MglA because MglA does not accumulate in mutants that cannot bind GTP. The threonine in PM3 of Mgl

  13. Site-specific receptor methylation of FrzCD in Myxococcus xanthus is controlled by a tetra-trico peptide repeat (TPR) containing regulatory domain of the FrzF methyltransferase

    PubMed Central

    Scott, Ansley E; Simon, Eric; Park, Samuel K; Andrews, Philip; Zusman, David R

    2008-01-01

    Myxococcus xanthus is a gliding bacterium with a complex life cycle that includes swarming, predation and fruiting body formation. Directed movements in M. xanthus are regulated by the Frz chemosensory system, which controls cell reversals. The Frz pathway requires the activity of FrzCD, a cytoplasmic methyl-accepting chemotaxis protein, and FrzF, a methyltransferase (CheR) containing an additional domain with three tetra trico-peptide repeats (TPRs). To investigate the role of the TPRs in FrzCD methylation, we used full-length FrzF and FrzF lacking its TPRs (FrzFCheR) to methylate FrzCD in vitro. FrzF methylated FrzCD on a single residue, E182, while FrzFCheR methylated FrzCD on three residues, E168, E175 and E182, indicating that the TPRs regulate site-specific methylation. E168 and E182 were predicted consensus methylation sites, but E175 is methylated on an HE pair. To determine the roles of these sites in vivo, we substituted each methylatable glutamate with either an aspartate or an alanine residue and determined the impact of the point mutants on single cell reversals, swarming and fruiting body formation. Single, double and triple methylation site mutants revealed that each site played a unique role in M. xanthus behaviour and that the pattern of receptor methylation determined receptor activity. This work also shows that methylation can both activate and inactivate the receptor. PMID:18554333

  14. Site-specific receptor methylation of FrzCD in Myxococcus xanthus is controlled by a tetra-trico peptide repeat (TPR) containing regulatory domain of the FrzF methyltransferase.

    PubMed

    Scott, Ansley E; Simon, Eric; Park, Samuel K; Andrews, Philip; Zusman, David R

    2008-08-01

    Myxococcus xanthus is a gliding bacterium with a complex life cycle that includes swarming, predation and fruiting body formation. Directed movements in M. xanthus are regulated by the Frz chemosensory system, which controls cell reversals. The Frz pathway requires the activity of FrzCD, a cytoplasmic methyl-accepting chemotaxis protein, and FrzF, a methyltransferase (CheR) containing an additional domain with three tetra trico-peptide repeats (TPRs). To investigate the role of the TPRs in FrzCD methylation, we used full-length FrzF and FrzF lacking its TPRs (FrzF(CheR)) to methylate FrzCD in vitro. FrzF methylated FrzCD on a single residue, E182, while FrzF(CheR) methylated FrzCD on three residues, E168, E175 and E182, indicating that the TPRs regulate site-specific methylation. E168 and E182 were predicted consensus methylation sites, but E175 is methylated on an HE pair. To determine the roles of these sites in vivo, we substituted each methylatable glutamate with either an aspartate or an alanine residue and determined the impact of the point mutants on single cell reversals, swarming and fruiting body formation. Single, double and triple methylation site mutants revealed that each site played a unique role in M. xanthus behaviour and that the pattern of receptor methylation determined receptor activity. This work also shows that methylation can both activate and inactivate the receptor. PMID:18554333

  15. The Bactofilin Cytoskeleton Protein BacM of Myxococcus xanthus Forms an Extended β-Sheet Structure Likely Mediated by Hydrophobic Interactions

    PubMed Central

    Xie, Kefang; Engelhardt, Harald; Bosch, Jürgen; Hoiczyk, Egbert

    2015-01-01

    Bactofilins are novel cytoskeleton proteins that are widespread in Gram-negative bacteria. Myxococcus xanthus, an important predatory soil bacterium, possesses four bactofilins of which one, BacM (Mxan_7475) plays an important role in cell shape maintenance. Electron and fluorescence light microscopy, as well as studies using over-expressed, purified BacM, indicate that this protein polymerizes in vivo and in vitro into ~3 nm wide filaments that further associate into higher ordered fibers of about 10 nm. Here we use a multipronged approach combining secondary structure determination, molecular modeling, biochemistry, and genetics to identify and characterize critical molecular elements that enable BacM to polymerize. Our results indicate that the bactofilin-determining domain DUF583 folds into an extended β-sheet structure, and we hypothesize a left-handed β-helix with polymerization into 3 nm filaments primarily via patches of hydrophobic amino acid residues. These patches form the interface allowing head-to-tail polymerization during filament formation. Biochemical analyses of these processes show that folding and polymerization occur across a wide variety of conditions and even in the presence of chaotropic agents such as one molar urea. Together, these data suggest that bactofilins are comprised of a structure unique to cytoskeleton proteins, which enables robust polymerization. PMID:25803609

  16. Interplay between type IV pili activity and exopolysaccharides secretion controls motility patterns in single cells of Myxococcus xanthus

    PubMed Central

    Hu, Wei; Gibiansky, Maxsim L.; Wang, Jing; Wang, Chuandong; Lux, Renate; Li, Yuezhong; Wong, Gerard C. L.; Shi, Wenyuan

    2016-01-01

    Myxococcus xanthus performs coordinated social motility of cell groups through the extension and retraction of type IV pili (TFP) on solid surfaces, which requires both TFP and exopolysaccharides (EPS). By submerging cells in a liquid medium containing 1% methylcellulose, M. xanthus TFP-driven motility was induced in isolated cells and independently of EPS. We measured and analyzed the movements of cells using community tracking algorithms, which combine single-cell resolution with statistics from large sample populations. Cells without significant multi-cellular social interactions have surprisingly complex behaviors: EPS− cells exhibited a pronounced increase in the tendency to stand vertically and moved with qualitatively different characteristics than other cells. A decrease in the EPS secretion of cells correlates with a higher instantaneous velocity, but with lower directional persistence in trajectories. Moreover, EPS− cells do not adhere to the surface as strongly as wild-type and EPS overproducing cells, and display a greater tendency to have large deviations between the direction of movement and the cell axis, with cell velocity showing only minimal dependence on the direction of movement. The emerging picture is that EPS does not simply provide rheological resistance to a single mechanism but rather that the availability of EPS impacts motility pattern. PMID:26821939

  17. Combinatorial Regulation of the dev Operon by MrpC2 and FruA during Myxococcus xanthus Development

    PubMed Central

    Campbell, Ashleigh; Viswanathan, Poorna; Barrett, Terry; Son, Bongjun; Saha, Shreya

    2014-01-01

    Proper expression of the dev operon is important for normal development of Myxococcus xanthus. When starved, these bacteria coordinate their gliding movements to build mounds that become fruiting bodies as some cells differentiate into spores. Mutations in the devTRS genes impair sporulation. Expression of the operon occurs within nascent fruiting bodies and depends in part on C signaling. Here, we report that expression of the dev operon, like that of several other C-signal-dependent genes, is subject to combinatorial control by the transcription factors MrpC2 and FruA. A DNA fragment upstream of the dev promoter was bound by a protein in an extract containing MrpC2, protecting the region spanning positions −77 to −54. Mutations in this region impaired binding of purified MrpC2 and abolished developmental expression of reporter fusions. The association of MrpC2 and/or its longer form, MrpC, with the dev promoter region depended on FruA in vivo, based on chromatin immunoprecipitation analysis, and purified FruA appeared to bind cooperatively with MrpC2 to DNA just upstream of the dev promoter in vitro. We conclude that cooperative binding of the two proteins to this promoter-proximal site is crucial for dev expression. 5′ deletion analysis implied a second upstream positive regulatory site, which corresponded to a site of weak cooperative binding of MrpC2 and FruA and boosted dev expression 24 h into development. This site is unique among the C-signal-dependent genes studied so far. Deletion of this site in the M. xanthus chromosome did not impair sporulation under laboratory conditions. PMID:25349159

  18. Contact- and Protein Transfer-Dependent Stimulation of Assembly of the Gliding Motility Machinery in Myxococcus xanthus

    PubMed Central

    Jakobczak, Beata; Keilberg, Daniela; Wuichet, Kristin; Søgaard-Andersen, Lotte

    2015-01-01

    Bacteria engage in contact-dependent activities to coordinate cellular activities that aid their survival. Cells of Myxococcus xanthus move over surfaces by means of type IV pili and gliding motility. Upon direct contact, cells physically exchange outer membrane (OM) lipoproteins, and this transfer can rescue motility in mutants lacking lipoproteins required for motility. The mechanism of gliding motility and its stimulation by transferred OM lipoproteins remain poorly characterized. We investigated the function of CglC, GltB, GltA and GltC, all of which are required for gliding. We demonstrate that CglC is an OM lipoprotein, GltB and GltA are integral OM β-barrel proteins, and GltC is a soluble periplasmic protein. GltB and GltA are mutually stabilizing, and both are required to stabilize GltC, whereas CglC accumulate independently of GltB, GltA and GltC. Consistently, purified GltB, GltA and GltC proteins interact in all pair-wise combinations. Using active fluorescently-tagged fusion proteins, we demonstrate that GltB, GltA and GltC are integral components of the gliding motility complex. Incorporation of GltB and GltA into this complex depends on CglC and GltC as well as on the cytoplasmic AglZ protein and the inner membrane protein AglQ, both of which are components of the gliding motility complex. Conversely, incorporation of AglZ and AglQ into the gliding motility complex depends on CglC, GltB, GltA and GltC. Remarkably, physical transfer of the OM lipoprotein CglC to a ΔcglC recipient stimulates assembly of the gliding motility complex in the recipient likely by facilitating the OM integration of GltB and GltA. These data provide evidence that the gliding motility complex in M. xanthus includes OM proteins and suggest that this complex extends from the cytoplasm across the cell envelope to the OM. These data add assembly of gliding motility complexes in M. xanthus to the growing list of contact-dependent activities in bacteria. PMID:26132848

  19. Lysyl-tRNA synthetase from Myxococcus xanthus catalyzes the formation of diadenosine penta- and hexaphosphates from adenosine tetraphosphate.

    PubMed

    Oka, Manami; Takegawa, Kaoru; Kimura, Yoshio

    2016-08-15

    Myxococcus xanthus lysyl-tRNA synthetase (LysS) produces diadenosine tetraphosphate (Ap4A) from ATP in the presence of Mn(2+); in the present study, it also generated Ap4 from ATP and triphosphate. When ATP and Ap4 were incubated with LysS and pyrophosphatase, first Ap4A, Ap5A, and ADP, and then Ap5, Ap6A, and Ap3A were generated. The results suggest that in the first step, LysS can form lysyl-AMP and lysyl-ADP intermediates from Ap4 and release triphosphate and diphosphate, respectively, whereas in the second step, it can produce Ap5 from lysyl-ADP with triphosphate, and Ap6A from lysyl-ADP with Ap4. In addition, in the presence of Ap4 and pyrophosphatase, but absence of ATP, LysS also generates diadenosine oligophosphates (ApnAs: n = 3-6). These results indicate that LysS has the ability to catalyze the formation of various ApnAs from Ap4 in the presence of pyrophosphatase. Furthermore, the formation of Ap4A by LysS was inhibited by tRNA(Lys) in the presence of 1 mM ATP. To the best of our knowledge, this is the first report of Ap5A and Ap6A synthesis by lysyl-tRNA synthetase. PMID:27392456

  20. Regulation of eukaryotic-like protein kinase activity of DspA from Myxococcus xanthus by autophosphorylation.

    PubMed

    Okamoto, Reiko; Takegawa, Kaoru; Kimura, Yoshio

    2014-02-01

    A Myxococcus xanthus DspA contains 12 subdomains characteristic of eukaryotic-like protein kinases but with an atypical sequence, RDxSPHN, in the catalytic loop, different from the consensus motifs observed in Ser/Thr kinases (RDxKxxN) or Tyr kinases (RDx(A/R)A(A/R)N). DspA phosphorylated myelin basic protein (MBP) on Ser and Thr residues. Mutations of the SPHN motif within the catalytic loop to KPHN or KPEN for Ser/Thr kinases, AARN for Tyr kinases and TPHN or TSHN for Dictyostelium Tyr kinases markedly reduced autophosphorylation and kinase activities. Phosphorylation assays, Western blot analysis and mutational analysis revealed that DspA is a dual-specificity kinase that autophosphorylates on two Thr residues (Thr-199 and Thr-201) in the activation loop and two Tyr residues (Tyr-35 and Tyr-111). RD kinases such as DspA are activated by phosphorylation in the activation loop. Replacement of Thr-199 or/and Thr-201 in the DspA activation loop by alanine also almost abolished autophosphorylation and kinase activities. In addition, mutation of either Tyr-35 or Tyr-111 to phenylalanine decreased kinase activities against MBP, and double mutation abolished kinase activity. These results suggested that DspA is activated by dual autophosphorylation of Thr residues in the activation loop, and autophosphorylation on two Tyr residues of DspA are required for high-level kinase activity. PMID:24194533

  1. Crystal structure of AibC, a reductase involved in alternative de novo isovaleryl coenzyme A biosynthesis in Myxococcus xanthus.

    PubMed

    Bock, Tobias; Müller, Rolf; Blankenfeldt, Wulf

    2016-08-01

    Isovaleryl coenzyme A (IV-CoA) performs a crucial role during development and fruiting-body formation in myxobacteria, which is reflected in the existence of a de novo biosynthetic pathway that is highly upregulated when leucine, the common precursor of IV-CoA, is limited. The final step in de novo IV-CoA biosynthesis is catalyzed by AibC, a medium-chain dehydrogenase/reductase. Here, the crystal structure of AibC from Myxococcus xanthus refined to 2.55 Å resolution is presented. The protein adopts two different conformations in the crystal lattice, which is a consequence of partial interaction with the purification tag. Based on this structure, it is suggested that AibC most probably uses a Zn(2+)-supported catalytic mechanism in which NADPH is preferred over NADH. Taken together, this study reveals structural details of the alternative IV-CoA-producing pathway in myxobacteria, which may serve as a base for further biotechnological research and biofuel production. PMID:27487931

  2. An atypical receiver domain controls the dynamic polar localization of the Myxococcus xanthus social motility protein FrzS

    PubMed Central

    Fraser, James S; Merlie, John P; Echols, Nathaniel; Weisfield, Shellie R; Mignot, Tâm; Wemmer, David E; Zusman, David R; Alber, Tom

    2007-01-01

    The Myxococcus xanthus FrzS protein transits from pole-to-pole within the cell, accumulating at the pole that defines the direction of movement in social (S) motility. Here we show using atomic-resolution crystallography and NMR that the FrzS receiver domain (RD) displays the conserved switch Tyr102 in an unusual conformation, lacks the conserved Asp phosphorylation site, and fails to bind Mg2+ or the phosphoryl analogue, Mg2+·BeF3. Mutation of Asp55, closest to the canonical site of RD phosphorylation, showed no motility phenotype in vivo, demonstrating that phosphorylation at this site is not necessary for domain function. In contrast, the Tyr102Ala and His92Phe substitutions on the canonical output face of the FrzS RD abolished S-motility in vivo. Single-cell fluorescence microscopy measurements revealed a striking mislocalization of these mutant FrzS proteins to the trailing cell pole in vivo. The crystal structures of the mutants suggested that the observed conformation of Tyr102 in the wild-type FrzS RD is not sufficient for function. These results support the model that FrzS contains a novel ‘pseudo-receiver domain’ whose function requires recognition of the RD output face but not Asp phosphorylation. PMID:17573816

  3. Phosphorylation-dependent localization of the response regulator FrzZ signals cell reversals in Myxococcus xanthus

    PubMed Central

    Kaimer, Christine; Zusman, David R.

    2013-01-01

    Summary The life cycle of Myxococcus xanthus includes coordinated group movement and fruiting body formation, and requires directed motility and controlled cell reversals. Reversals are achieved by inverting cell polarity and re-organizing many motility proteins. The Frz chemosensory pathway regulates the frequency of cell reversals. While it has been established that phosphotransfer from the kinase FrzE to the response regulator FrzZ is required, it is unknown how phosphorylated FrzZ, the putative output of the pathway, targets the cell polarity axis. In this study, we used Phos-tag SDS-PAGE to determine the cellular level of phospho-FrzZ under different growth conditions and in Frz signaling mutants. We detected consistent FrzZ phosphorylation, albeit with a short half-life, in cells grown on plates, but not from liquid culture. The available pool of phospho-FrzZ correlated with reversal frequencies, with higher levels found in hyper-reversing mutants. Phosphorylation was not detected in hypo-reversing mutants. Fluorescence microscopy revealed that FrzZ is recruited to the leading cell pole upon phosphorylation and switches to the opposite pole during reversals. These results are consistent with the hypothesis that the Frz pathway modulates reversal frequency through a localized response regulator that targets cell polarity regulators at the leading cell pole. PMID:23551551

  4. AglZ regulates adventurous (A-) motility in Myxococcus xanthus through its interaction with the cytoplasmic receptor, FrzCD

    PubMed Central

    Mauriello, Emilia M.F.; Nan, Beiyan; Zusman, David R.

    2014-01-01

    Summary Myxococcus xanthus moves by gliding motility powered by Type IV pili (S-motility) and distributed motor complexes (A-motility). The Frz chemosensory pathway controls reversals for both motility systems. However, it is unclear how the Frz pathway can communicate with these different systems. In this paper, we show that FrzCD, the Frz pathway receptor, interacts with AglZ, a protein associated with A-motility. Affinity chromatography and cross-linking experiments showed that the FrzCD-AglZ interaction occurs between the uncharacterized N-terminal region of FrzCD and the N-terminal pseudo-receiver domain of AglZ. Fluorescence microscopy showed AglZ-mCherry and FrzCD-GFP localized in clusters that occupy different positions in cells. To study the role of the Frz system in the regulation of A-motility, we constructed aglZ frzCD double mutants and aglZ frzCD pilA triple mutants. To our surprise, these mutants, predicted to show no A-motility (A−S+) or no motility at all (A−S−), respectively, showed restored A-motility. These results indicate that AglZ modulates a FrzCD activity that inhibits A-motility. We hypothesize that AglZ-FrzCD interactions are favored when cells are isolated and moving by A-motility and inhibited when S-motility predominates and A-motility is reduced. PMID:19400788

  5. Identification of the Ω4406 Regulatory Region, a Developmental Promoter of Myxococcus xanthus, and a DNA Segment Responsible for Chromosomal Position-Dependent Inhibition of Gene Expression

    PubMed Central

    Loconto, Jennifer; Viswanathan, Poorna; Nowak, Scott J.; Gloudemans, Monica; Kroos, Lee

    2005-01-01

    When starved, Myxococcus xanthus cells send signals to each other that coordinate their movements, gene expression, and differentiation. C-signaling requires cell-cell contact, and increasing contact brought about by cell alignment in aggregates is thought to increase C-signaling, which induces expression of many genes, causing rod-shaped cells to differentiate into spherical spores. C-signaling involves the product of the csgA gene. A csgA mutant fails to express many genes that are normally induced after about 6 h into the developmental process. One such gene was identified by insertion of Tn5 lac at site Ω4406 in the M. xanthus chromosome. Tn5 lac fused transcription of lacZ to the upstream Ω4406 promoter. In this study, the Ω4406 promoter region was identified by analyzing mRNA and by testing different upstream DNA segments for the ability to drive developmental lacZ expression in M. xanthus. The 5′ end of Ω4406 mRNA mapped to approximately 1.3 kb upstream of the Tn5 lac insertion. A 1.0-kb DNA segment from 0.8 to 1.8 kb upstream of the Tn5 lac insertion, when fused to lacZ and integrated at a phage attachment site in the M. xanthus chromosome, showed a similar pattern of developmental expression as Tn5 lac Ω4406. The DNA sequence upstream of the putative transcriptional start site was strikingly similar to promoter regions of other C-signal-dependent genes. Developmental lacZ expression from the 1.0-kb segment was abolished in a csgA mutant but was restored upon codevelopment of the csgA mutant with wild-type cells, which supply C-signal, demonstrating that the Ω4406 promoter responds to extracellular C-signaling. Interestingly, the 0.8-kb DNA segment immediately upstream of Tn5 lac Ω4406 inhibited expression of a downstream lacZ reporter in transcriptional fusions integrated at a phage attachment site in the chromosome but not at the normal Ω4406 location. To our knowledge, this is the first example in M. xanthus of a chromosomal position

  6. The Myxococcus xanthus rfbABC operon encodes an ATP-binding cassette transporter homolog required for O-antigen biosynthesis and multicellular development.

    PubMed

    Guo, D; Bowden, M G; Pershad, R; Kaplan, H B

    1996-03-01

    A wild-type sasA locus is critical for Myxococcus xanthus multicellular development. Mutations in the sasA locus cause defective fruiting body formation, reduce sporulation, and restore developmental expression of the early A-signal-dependent gene 4521 in the absence of A signal. The wild-type sasA locus has been located on a 14-kb cloned fragment of the M. xanthus chromosome. The nucleotide sequence of a 7-kb region containing the complete sasA locus was determined. Three open reading frames encoded by the genes, designated rfbA, B and C were identified. The deduced amino acid sequences of rfbA and rfbB show identity to the integral membrane domains and ATPase domains, respectively, of the ATP-binding cassette (ABC) transporter family. The highest identities are to a set of predicted ABC transporters required for the biosynthesis of lipopolysaccharide O-antigen in certain gram-negative bacteria. The rfbC gene encodes a predicted protein of 1,276 amino acids. This predicted protein contains a region of 358 amino acids that is 33.8% identical to the Yersinia enterocolitica O3 rfbH gene product, which is also required for O-antigen biosynthesis. Immunoblot analysis revealed that the sasA1 mutant, which was found to encode a nonsense codon in the beginning of rfbA, produced less O-antigen than sasA+ strains. These data indicate that the sasA locus is required for the biosynthesis of O-antigen and, when mutated, results in A-signal-independent expression of 4521. PMID:8626291

  7. The Hsp70-like StkA functions between T4P and Dif signaling proteins as a negative regulator of exopolysaccharide in Myxococcus xanthus

    PubMed Central

    Moak, Pamela L.; Black, Wesley P.; Wallace, Regina A.; Li, Zhuo

    2015-01-01

    Myxococcus xanthus displays a form of surface motility known as social (S) gliding. It is mediated by the type IV pilus (T4P) and requires the exopolysaccharide (EPS) to function. It is clear that T4P retraction powers S motility. EPS on a neighboring cell or deposited on a gliding surface is proposed to anchor the distal end of a pilus and trigger T4P retraction at its proximal end. Inversely, T4P has been shown to regulate EPS production upstream of the Dif signaling pathway. Here we describe the isolation of two Tn insertions at the stk locus which had been known to play roles in cellular cohesion and formation of cell groups. An insertion in stkA (MXAN_3474) was identified based on its ability to restore EPS to a pilA deletion mutant. The stkA encodes a DnaK or Hsp70 homolog and it is upstream of stkB (MXAN_3475) and stkC (MXAN_3476). A stkB insertion was identified in a separate genetic screen because it eliminated EPS production of an EPS+ parental strain. Our results with in-frame deletions of these three stk genes indicated that the stkA mutant produced increased level of EPS while stkB and stkC mutants produced less EPS relative to the wild type. S motility and developmental aggregation were affected by deletions of stkA and stkB but only minimally by the deletion of stkC. Genetic epistasis indicated that StkA functions downstream of T4P but upstream of the Dif proteins as a negative regulator of EPS production in M. xanthus. PMID:25674362

  8. The Myxococcus xanthus rfbABC operon encodes an ATP-binding cassette transporter homolog required for O-antigen biosynthesis and multicellular development.

    PubMed Central

    Guo, D; Bowden, M G; Pershad, R; Kaplan, H B

    1996-01-01

    A wild-type sasA locus is critical for Myxococcus xanthus multicellular development. Mutations in the sasA locus cause defective fruiting body formation, reduce sporulation, and restore developmental expression of the early A-signal-dependent gene 4521 in the absence of A signal. The wild-type sasA locus has been located on a 14-kb cloned fragment of the M. xanthus chromosome. The nucleotide sequence of a 7-kb region containing the complete sasA locus was determined. Three open reading frames encoded by the genes, designated rfbA, B and C were identified. The deduced amino acid sequences of rfbA and rfbB show identity to the integral membrane domains and ATPase domains, respectively, of the ATP-binding cassette (ABC) transporter family. The highest identities are to a set of predicted ABC transporters required for the biosynthesis of lipopolysaccharide O-antigen in certain gram-negative bacteria. The rfbC gene encodes a predicted protein of 1,276 amino acids. This predicted protein contains a region of 358 amino acids that is 33.8% identical to the Yersinia enterocolitica O3 rfbH gene product, which is also required for O-antigen biosynthesis. Immunoblot analysis revealed that the sasA1 mutant, which was found to encode a nonsense codon in the beginning of rfbA, produced less O-antigen than sasA+ strains. These data indicate that the sasA locus is required for the biosynthesis of O-antigen and, when mutated, results in A-signal-independent expression of 4521. PMID:8626291

  9. Enzymatic characteristics of an ApaH-like phosphatase, PrpA, and a diadenosine tetraphosphate hydrolase, ApaH, from Myxococcus xanthus.

    PubMed

    Sasaki, Masashi; Takegawa, Kaoru; Kimura, Yoshio

    2014-09-17

    We characterized the activities of the Myxococcus xanthus ApaH-like phosphatases PrpA and ApaH, which share homologies with both phosphoprotein phosphatases and diadenosine tetraphosphate (Ap4A) hydrolases. PrpA exhibited a phosphatase activity towards p-nitrophenyl phosphate (pNPP), tyrosine phosphopeptide and tyrosine-phosphorylated protein, and a weak hydrolase activity towards ApnA and ATP. In the presence of Mn(2+), PrpA hydrolyzed Ap4A into AMP and ATP, whereas in the presence of Co(2+) PrpA hydrolyzed Ap4A into two molecules of ADP. ApaH exhibited high phosphatase activity towards pNPP, and hydrolase activity towards ApnA and ATP. Mn(2+) was required for ApaH-mediated pNPP dephosphorylation and ATP hydrolysis, whereas Co(2+) was required for ApnA hydrolysis. Thus, PrpA and ApaH may function mainly as a tyrosine protein phosphatase and an ApnA hydrolase, respectively. PMID:25107648

  10. Nutrient-Regulated Proteolysis of MrpC Halts Expression of Genes Important for Commitment to Sporulation during Myxococcus xanthus Development

    PubMed Central

    Rajagopalan, Ramya

    2014-01-01

    Starved Myxococcus xanthus cells glide to aggregation centers and form fruiting bodies in which rod-shaped cells differentiate into ovoid spores. Commitment to development was investigated by adding nutrients at specific times after starvation and determining whether development halted or proceeded. At 24 h poststarvation, some rod-shaped cells were committed to subsequent shape change and to becoming sonication-resistant spores, but nutrients caused partial disaggregation of fruiting bodies. By 30 h poststarvation, 10-fold more cells were committed to becoming sonication-resistant spores, and compact fruiting bodies persisted after nutrient addition. During the critical period of commitment around 24 to 30 h poststarvation, the transcription factors MrpC and FruA cooperatively regulate genes important for sporulation. FruA responds to short-range C-signaling, which increases as cells form fruiting bodies. MrpC was found to be highly sensitive to nutrient-regulated proteolysis both before and during the critical period of commitment to sporulation. The rapid turnover of MrpC upon nutrient addition to developing cells halted expression of the dev operon, which is important for sporulation. Regulated proteolysis of MrpC appeared to involve ATP-independent metalloprotease activity and may provide a mechanism for monitoring whether starvation persists and halting commitment to sporulation if nutrients reappear. PMID:24837289

  11. In depth analysis of the mechanism of action of metal-dependent sigma factors: characterization of CorE2 from Myxococcus xanthus

    PubMed Central

    Marcos-Torres, Francisco Javier; Pérez, Juana; Gómez-Santos, Nuria; Moraleda-Muñoz, Aurelio; Muñoz-Dorado, José

    2016-01-01

    Extracytoplasmic function sigma factors represent the third pillar of signal-transduction mechanisms in bacteria. The variety of stimuli they recognize and mechanisms of action they use have allowed their classification into more than 50 groups. We have characterized CorE2 from Myxococcus xanthus, which belongs to group ECF44 and upregulates the expression of two genes when it is activated by cadmium and zinc. Sigma factors of this group contain a Cys-rich domain (CRD) at the C terminus which is essential for detecting metals. Point mutations at the six Cys residues of the CRD have revealed the contribution of each residue to CorE2 activity. Some of them are essential, while others are either dispensable or their mutations only slightly affect the activity of the protein. However, importantly, mutation of Cys174 completely shifts the specificity of CorE2 from cadmium to copper, indicating that the Cys arrangement of the CRD determines the metal specificity. Moreover, the conserved CxC motif located between the σ2 domain and the σ4.2 region has also been found to be essential for activity. The results presented here contribute to our understanding of the mechanism of action of metal-dependent sigma factors and help to define new common features of the members of this group of regulators. PMID:26951374

  12. A RelA-dependent two-tiered regulated proteolysis cascade controls synthesis of a contact-dependent intercellular signal in Myxococcus xanthus.

    PubMed

    Konovalova, Anna; Löbach, Stephanie; Søgaard-Andersen, Lotte

    2012-04-01

    Proteolytic cleavage of precursor proteins to generate intercellular signals is a common mechanism in all cells. In Myxococcus xanthus the contact-dependent intercellular C-signal is a 17 kDa protein (p17) generated by proteolytic cleavage of the 25 kDa csgA protein (p25), and is essential for starvation-induced fruiting body formation. p25 accumulates in the outer membrane and PopC, the protease that cleaves p25, in the cytoplasm of vegetative cells. PopC is secreted in response to starvation, therefore, restricting p25 cleavage to starving cells. We focused on identifying proteins critical for PopC secretion in response to starvation. PopC secretion depends on the (p)ppGpp synthase RelA and the stringent response, and is regulated post-translationally. PopD, which is encoded in an operon with PopC, forms a soluble complex with PopC and inhibits PopC secretion whereas the integral membrane AAA+ protease FtsH(D) is required for PopC secretion. Biochemical and genetic evidence suggest that in response to starvation, RelA is activated and induces the degradation of PopD thereby releasing pre-formed PopC for secretion and that FtsH(D) is important for PopD degradation. Hence, regulated PopC secretion depends on regulated proteolysis. Accordingly, p17 synthesis depends on a proteolytic cascade including FtsH(D) -dependent degradation of PopD and PopC-dependent cleavage of p25. PMID:22404381

  13. The orphan histidine protein kinase SgmT is a c-di-GMP receptor and regulates composition of the extracellular matrix together with the orphan DNA binding response regulator DigR in Myxococcus xanthus

    PubMed Central

    Petters, Tobias; Zhang, Xin; Nesper, Jutta; Treuner-Lange, Anke; Gomez-Santos, Nuria; Hoppert, Michael; Jenal, Urs; Søgaard-Andersen, Lotte

    2012-01-01

    In Myxococcus xanthus the extracellular matrix is essential for type IV pili-dependent motility and starvation-induced fruiting body formation. Proteins of two-component systems including the orphan DNA binding response regulator DigR are essential in regulating the composition of the extracellular matrix. We identify the orphan hybrid histidine kinase SgmT as the partner kinase of DigR. In addition to kinase and receiver domains, SgmT consists of an N-terminal GAF domain and a C-terminal GGDEF domain. The GAF domain is the primary sensor domain. The GGDEF domain binds the second messenger bis-(3′-5′)-cyclic-dimeric-GMP (c-di-GMP) and functions as a c-di-GMP receptor to spatially sequester SgmT. We identify the DigR binding site in the promoter of the fibA gene, which encodes an abundant extracellular matrix metalloprotease. Whole-genome expression profiling experiments in combination with the identified DigR binding site allowed the identification of the DigR regulon and suggests that SgmT/DigR regulates the expression of genes for secreted proteins and enzymes involved in secondary metabolite synthesis. We suggest that SgmT/DigR regulates extracellular matrix composition and that SgmT activity is regulated by two sensor domains with ligand binding to the GAF domain resulting in SgmT activation and c-di-GMP binding to the GGDEF domain resulting in spatial sequestration of SgmT. PMID:22394314

  14. The Type IV Pilus Assembly ATPase PilB of Myxococcus xanthus Interacts with the Inner Membrane Platform Protein PilC and the Nucleotide-binding Protein PilM.

    PubMed

    Bischof, Lisa Franziska; Friedrich, Carmen; Harms, Andrea; Søgaard-Andersen, Lotte; van der Does, Chris

    2016-03-25

    Type IV pili (T4P) are ubiquitous bacterial cell surface structures, involved in processes such as twitching motility, biofilm formation, bacteriophage infection, surface attachment, virulence, and natural transformation. T4P are assembled by machinery that can be divided into the outer membrane pore complex, the alignment complex that connects components in the inner and outer membrane, and the motor complex in the inner membrane and cytoplasm. Here, we characterize the inner membrane platform protein PilC, the cytosolic assembly ATPase PilB of the motor complex, and the cytosolic nucleotide-binding protein PilM of the alignment complex of the T4P machinery ofMyxococcus xanthus PilC was purified as a dimer and reconstituted into liposomes. PilB was isolated as a monomer and bound ATP in a non-cooperative manner, but PilB fused to Hcp1 ofPseudomonas aeruginosaformed a hexamer and bound ATP in a cooperative manner. Hexameric but not monomeric PilB bound to PilC reconstituted in liposomes, and this binding stimulated PilB ATPase activity. PilM could only be purified when it was stabilized by a fusion with a peptide corresponding to the first 16 amino acids of PilN, supporting an interaction between PilM and PilN(1-16). PilM-N(1-16) was isolated as a monomer that bound but did not hydrolyze ATP. PilM interacted directly with PilB, but only with PilC in the presence of PilB, suggesting an indirect interaction. We propose that PilB interacts with PilC and with PilM, thus establishing the connection between the alignment and the motor complex. PMID:26851283

  15. Structure-Function Dissection of Myxococcus xanthus CarD N-Terminal Domain, a Defining Member of the CarD_CdnL_TRCF Family of RNA Polymerase Interacting Proteins

    PubMed Central

    Bernal-Bernal, Diego; Gallego-García, Aránzazu; García-Martínez, Gema; García-Heras, Francisco; Jiménez, María Angeles; Padmanabhan, S.; Elías-Arnanz, Montserrat

    2015-01-01

    Two prototypes of the large CarD_CdnL_TRCF family of bacterial RNA polymerase (RNAP)-binding proteins, Myxococcus xanthus CarD and CdnL, have distinct functions whose molecular basis remain elusive. CarD, a global regulator linked to the action of several extracytoplasmic function (ECF) σ-factors, binds to the RNAP β subunit (RNAP-β) and to protein CarG via an N-terminal domain, CarDNt, and to DNA via an intrinsically unfolded C-terminal domain resembling eukaryotic high-mobility-group A (HMGA) proteins. CdnL, a CarDNt-like protein that is essential for cell viability, is implicated in σA-dependent rRNA promoter activation and interacts with RNAP-β but not with CarG. While the HMGA-like domain of CarD by itself is inactive, we find that CarDNt has low but observable ability to activate ECF σ-dependent promoters in vivo, indicating that the C-terminal DNA-binding domain is required to maximize activity. Our structure-function dissection of CarDNt reveals an N-terminal, five-stranded β -sheet Tudor-like domain, CarD1–72, whose structure and contacts with RNAP-β mimic those of CdnL. Intriguingly, and in marked contrast to CdnL, CarD mutations that disrupt its interaction with RNAP-β did not annul activity. Our data suggest that the CarDNt C-terminal segment, CarD61–179, may be structurally distinct from its CdnL counterpart, and that it houses at least two distinct and crucial function determinants: (a) CarG-binding, which is specific to CarD; and (b) a basic residue stretch, which is also conserved and functionally required in CdnL. This study highlights the evolution of shared and divergent interactions in similar protein modules that enable the distinct activities of two related members of a functionally important and widespread bacterial protein family. PMID:25811865

  16. Generation of food-grade recombinant Lactobacillus casei delivering Myxococcus xanthus prolyl endopeptidase.

    PubMed

    Alvarez-Sieiro, Patricia; Martin, Maria Cruz; Redruello, Begoña; Del Rio, Beatriz; Ladero, Victor; Palanski, Brad A; Khosla, Chaitan; Fernandez, Maria; Alvarez, Miguel A

    2014-08-01

    Prolyl endopeptidases (PEP) (EC 3.4.21.26), a family of serine proteases with the ability to hydrolyze the peptide bond on the carboxyl side of an internal proline residue, are able to degrade immunotoxic peptides responsible for celiac disease (CD), such as a 33-residue gluten peptide (33-mer). Oral administration of PEP has been suggested as a potential therapeutic approach for CD, although delivery of the enzyme to the small intestine requires intrinsic gastric stability or advanced formulation technologies. We have engineered two food-grade Lactobacillus casei strains to deliver PEP in an in vitro model of small intestine environment. One strain secretes PEP into the extracellular medium, whereas the other retains PEP in the intracellular environment. The strain that secretes PEP into the extracellular medium is the most effective to degrade the 33-mer and is resistant to simulated gastrointestinal stress. Our results suggest that in the future, after more studies and clinical trials, an engineered food-grade Lactobacillus strain may be useful as a vector for in situ production of PEP in the upper small intestine of CD patients. PMID:24752841

  17. Generation of food-grade recombinant Lactobacillus casei delivering Myxococcus xanthus prolyl endopeptidase

    PubMed Central

    Alvarez-Sieiro, Patricia; Martin, Maria Cruz; Redruello, Begoña; del Rio, Beatriz; Ladero, Victor; Palanski, Brad A.; Khosla, Chaitan; Fernandez, Maria; Alvarez, Miguel A.

    2015-01-01

    Prolyl endopeptidases (PEP), a family of serine proteases with the ability to hydrolyze the peptide bond on the carboxyl side of an internal proline residue, are able to degrade immunotoxic peptides responsible for celiac disease (CD), such as a 33-residue gluten peptide (33-mer). Oral administration of PEP has been suggested as a potential therapeutic approach for CD, although delivery of the enzyme to the small intestine requires intrinsic gastric stability or advanced formulation technologies. We have engineered two food-grade Lactobacillus casei strains to deliver PEP in an in vitro model of small intestine environment. One strain secretes PEP into the extracellular medium, whereas the other retains PEP in the intracellular environment. The strain that secretes PEP into the extracellular medium is the most effective to degrade the 33-mer and is resistant to simulated gastrointestinal stress. Our results suggest that in a future, after more studies and clinical trials, an engineered food-grade Lactobacillus strain may be useful as a vector for in situ production of PEP in the upper small intestine of CD patients. PMID:24752841

  18. Stability of a Random Walk Model for Fruiting Body Aggregation in M. xanthus

    NASA Astrophysics Data System (ADS)

    McKenzie-Smith, G. C.; Schüttler, H. B.; Cotter, C.; Shimkets, L.

    2015-03-01

    Myxococcus xanthus exhibits the social starvation behavior of aggregation into a fruiting body containing myxospores able to survive harsh conditions. During fruiting body aggregation, individual bacteria follow random walk paths determined by randomly selected runtimes, turning angles, and speeds. We have simulated this behavior in terms of a continuous-time random walk (CTRW) model, re-formulated as a system of integral equations, describing the angle-resolved cell density, R(r, t, θ), at position r and cell orientation angle θ at time t, and angle-integrated ambient cell density ρ(r, t). By way of a linear stability analysis, we investigated whether a uniform cell density R0 will be unstable for a small non-uniform density perturbation δR(r, t, θ). Such instability indicates aggregate formation, whereas stability indicates absence of aggregation. We show that a broadening of CTRW distributions of the random speed and/or random runtimes strongly favors aggregation. We also show that, in the limit of slowly-varying (long-wavelength) density perturbations, the time-dependent linear density response can be approximated by a drift-diffusion model for which we calculate diffusion and drift coefficients as functions of the CTRW model parameters. Funded by the Fungal Genomics and Computational Biology REU at UGA.

  19. Myxococcus CsgA, Drosophila Sniffer, and human HSD10 are cardiolipin phospholipases

    PubMed Central

    Boynton, Tye O'Hara; Shimkets, Lawrence Joseph

    2015-01-01

    Myxococcus xanthus development requires CsgA, a member of the short-chain alcohol dehydrogenase (SCAD) family of proteins. We show that CsgA and SocA, a protein that can replace CsgA function in vivo, oxidize the 2′-OH glycerol moiety on cardiolipin and phosphatidylglycerol to produce diacylglycerol (DAG), dihydroxyacetone, and orthophosphate. A lipid extract enriched in DAGs from wild-type cells initiates development and lipid body production in a csgA mutant to bypass the mutational block. This novel phospholipase C-like reaction is widespread. SCADs that prevent neurodegenerative disorders, such as Drosophila Sniffer and human HSD10, oxidize cardiolipin with similar kinetic parameters. HSD10 exhibits a strong preference for cardiolipin with oxidized fatty acids. This activity is inhibited in the presence of the amyloid β peptide. Three HSD10 variants associated with neurodegenerative disorders are inactive with cardiolipin. We suggest that HSD10 protects humans from reactive oxygen species by removing damaged cardiolipin before it induces apoptosis. PMID:26338420

  20. Comparison of polysaccharides produced by Myxococcus strains.

    PubMed

    Sutherland, I W; Thomson, S

    1975-07-01

    Exopolysaccharides were prepared from cultures of four Myxococcus strains grown on solid and in liquid media, and also from the fruiting bodies. Lipopolysaccharides could be extracted with aqueous phenol from the vegetative bacteria, but were absent from microcysts. Mannose and D-glucose were present in all the exopolysaccharides and three of the lipopolysaccharides examined. Other monosaccharides identified in the exopolysaccharides were D-galactose, N-acetylglucosamine and N-acetylgalactosamine. The composition of the lipopolysaccharides was more complex than that of the exopolysaccharides and, in addition to the neutral hexoses and amino sugars, rhamnose was identified in two preparations and ribose in another. No lipopolysaccharide preparations contained O-methyl xylose or heptose. The polysaccharides secreted by the bacillary forms grown on solid or in liquid media closely resembled the polysaccharides isolated from the fruiting bodies, in which they provided a matrix surrounding the microcysts. Each pair of polysaccharides contained the same monosaccharides, although in slightly different proportions. Differences were found in preparations from different strains. These results suggest that in the development cycle of the genus Myxococcus, considerable use is made of pre-existing enzyme systems to synthesize the precursors necessary for polysaccharide synthesis. Any specific difference between the polysaccharide produced by the bacilli and that surrounding the microcysts may lie in the fine structure, rather than in the individual components. PMID:807682

  1. Role of cell bending and slime navigation in swarms of M. xanthus

    NASA Astrophysics Data System (ADS)

    Harvey, Cameron; Kaiser, Dale; Alber, Mark

    2012-02-01

    Many bacteria use motility described as swarming to colonize surfaces that allows them to optimize their access to nutrients. The swarming of the bacterium M. xanthus on surfaces is a remarkable interplay between motility mechanisms, cell flexibility, cell-cell adhesive interactions and directional reversals. The properties of individual cells from different mutant strains and density regimes will be demonstrated in this talk. Then, a computational model based on subcellular elements for cell representation and implemented on graphical processing units (GPUs) will be presented. High-quality high magnification movies of bacterial motility together with biologically justified computational simulations will be used for investigation of collective motion and order in swarming populations of bacteria. Collective motion will be shown to include the dynamical formation of cell clusters as well as streams of cells moving over networks of cell-generated slime tracks.

  2. KR025, a new cytotoxic compound from Myxococcus fulvus.

    PubMed

    Ahn, J W; Woo, S H; Lee, C O; Cho, K Y; Kim, B S

    1999-03-01

    A new bithiazole, KR-025 (1), was isolated from Myxococcus fulvus. Its structure was elucidated by spectroscopic analysis. In addition to 1, the strain produced relatively large quantities of a second, closely related antibiotic, myxothiazol. These compounds demonstrated potent cytotoxicity against human tumor cells. PMID:10096868

  3. Lysophosphatidylethanolamine Is a Substrate for the Short-Chain Alcohol Dehydrogenase SocA from Myxococcus xanthus▿ †

    PubMed Central

    Avadhani, Madhavi; Geyer, Roland; White, David C.; Shimkets, Lawrence J.

    2006-01-01

    Short-chain alcohol dehydrogenases (SCADHs) synthesize a variety of intercellular signals and other chemically diverse products. It is difficult to predict the substrate of a SCADH on the basis of amino acid sequence homology, as the substrates are not known for most SCADHs. In Myxococcus xanthus, the SCADH CsgA is responsible for C signaling during fruiting body development, although the mechanism is unclear. Overexpression of the SCADH SocA compensates for the lack of CsgA and restores development and C signaling in csgA mutants. The potential of SocA in generating the C signal enzymatically was explored by developing a dehydrogenase assay-based screen to purify the SocA substrate(s). A SocA substrate was extracted from M. xanthus cells with acidified ethyl acetate and sequentially purified by solid-phase extraction on silica gel and by reverse-phase high-performance liquid chromatography. The fraction with the highest SocA dehydrogenase activity contained the lysophospholipid 1-acyl 2-hydroxy-sn-glycerophosphoethanolamine (lyso-PE) as indicated by the fragment ions and a phosphatidylethanolamine-specific neutral loss scan following liquid chromatography coupled to mass spectrometry. The abundant lysophospholipid with the mass m/z 450 (molecular ion [M-H]−) had a monounsaturated acyl chain with 16 carbons. SocA oxidizes lyso-PE containing either saturated or unsaturated fatty acids but exhibits poor activity on l-α-glycerophosphorylethanolamine, suggesting that an acyl chain is important for activity. Of the five different head groups, only ethanolamine showed appreciable activity. The apparent Km and Vmax for lyso-PE 18:1 were 116 μM and 875 μmol min−1 mg−1, respectively. The catalytic efficiency (kcat/Km) was 1 × 108 M−1 s−1. The proposed product, 1-acyloxy-3-(2-aminoethylphosphatyl) acetone was unstable, and the fragmented products were unable to rescue csgA mutant development. The active fraction from thin-layer chromatography also contained an

  4. Purification and properties of an extracellular protease from Myxococcus virescens.

    PubMed Central

    Gnosspelius, G

    1978-01-01

    An extracellular protease from Myxococcus virescens was purified by phosphate precipitation, gel exclusion, and ion-exchange chromatography. The enzyme appeared homogeneous upon disc electrophoresis. The molecular weight of the protease was estimated to be 26,000. The enzyme was rapidly inactivated by ethylenediaminetetraacetate, but the activity could be partially restored by divalent cations. Diisopropylphosphorofluoridate inhibited enzyme activity completely. Michaelis-Menten kinetics were obeyed with casein and hemoglobin as substrates. First-order kinetics were obtained with elastin as the substrate, provided trypsin was in excess. Petidolytic activity indicated that the peptide bonds hydrolyzed by the enzyme were mainly those involving amino acids with nonpolar side chains. PMID:22536

  5. Complete Genome Sequence and Comparative Genomics of a Novel Myxobacterium Myxococcus hansupus

    PubMed Central

    Sharma, Gaurav; Narwani, Tarun; Subramanian, Srikrishna

    2016-01-01

    Myxobacteria, a group of Gram-negative aerobes, belong to the class δ-proteobacteria and order Myxococcales. Unlike anaerobic δ-proteobacteria, they exhibit several unusual physiogenomic properties like gliding motility, desiccation-resistant myxospores and large genomes with high coding density. Here we report a 9.5 Mbp complete genome of Myxococcus hansupus that encodes 7,753 proteins. Phylogenomic and genome-genome distance based analysis suggest that Myxococcus hansupus is a novel member of the genus Myxococcus. Comparative genome analysis with other members of the genus Myxococcus was performed to explore their genome diversity. The variation in number of unique proteins observed across different species is suggestive of diversity at the genus level while the overrepresentation of several Pfam families indicates the extent and mode of genome expansion as compared to non-Myxococcales δ-proteobacteria. PMID:26900859

  6. Myxothiazol, an antibiotic from Myxococcus fulvus (myxobacterales). I. Cultivation, isolation, physico-chemical and biological properties.

    PubMed

    Gerth, K; Irschik, H; Reichenbach, H; Trowitzsch, W

    1980-12-01

    Myxothiazol (AB-Mx f16-1), a new antifungal antibiotic, is produced by the myxobacterium Myxococcus fulvus strain Mx f16. It is active against many filamentous fungi, and completely inhibits growth of Mucor hiemalis at a concentration of 2 micrograms/ml. The molecular formula of myxothiazol was determined to e C25H33N3O3S2. PMID:6788741

  7. Glycine Betaine Biosynthesized from Glycine Provides an Osmolyte for Cell Growth and Spore Germination during Osmotic Stress in Myxococcus xanthus▿

    PubMed Central

    Kimura, Yoshio; Kawasaki, Shinji; Yoshimoto, Hinae; Takegawa, Kaoru

    2010-01-01

    Glycine sarcosine methyltransferase (Gsm) and sarcosine dimethylglycine methyltransferase (Sdm) catalyze glycine betaine synthesis from glycine. Disruption of the M. xanthus gsmA (MXAN 7068) or sdmA (MXAN 3190) gene, encoding Gsm or Sdm homologue proteins, respectively, generated mutants that exhibited a longer lag period of growth and delayed spore germination under osmostress. PMID:20023011

  8. Lethal effects of abamectin on the aquatic organisms Daphnia similis, Chironomus xanthus and Danio rerio.

    PubMed

    Novelli, Andréa; Vieira, Bruna Horvath; Cordeiro, Daniela; Cappelini, Luciana Teresa Dias; Vieira, Eny Maria; Espíndola, Evaldo Luiz Gaeta

    2012-01-01

    Abamectin is used as an acaricide and insecticide for fruits, vegetables and ornamental plants, as well as a parasiticide for animals. One of the major problems of applying pesticides to crops is the likelihood of contaminating aquatic ecosystems by drift or runoff. Therefore, toxicity tests in the laboratory are important tools to predict the effects of chemical substances in aquatic ecosystems. The aim of this study was to assess the potential hazards of abamectin to the freshwater biota and consequently the possible losses of ecological services in contaminated water bodies. For this purpose, we identified the toxicity of abamectin on daphnids, insects and fish. Abamectin was highly toxic, with an EC(50) 48 h for Daphnia similis of 5.1 ng L(-1), LC(50) 96 h for Chironomus xanthus of 2.67 μg L(-1) and LC(50) 48 h for Danio rerio of 33 μg L(-1). PMID:21955349

  9. Determination of bacterial ammonia pools using Myxococcus virescens as an example.

    PubMed

    Gerth, K; Reichenbach, H

    1986-01-01

    Samples (150 microliters) from liquid cultures of known cell density of Myxococcus virescens (Myxobacterales) were used for the determination of the intracellular NH3/NH+4 concentrations (= total ammonia). The cells were separated from the culture broth within 30 s by centrifugation through a silicone layer and were lysed immediately with 20 microliters of a disintegration liquid at the bottom of the centrifugation tube. The ammonia concentrations of the lysates were determined with a Dohrmann nitrogen analyzer. The intracellular ammonia concentrations were calculated after corrections for trapped supernatant had been made by adding radioactive glucose, which cannot be taken up by the organism. Control experiments with permeabilized cells and radioactive methylamine corroborated the reliability of the method. PMID:3082243

  10. Project EAGLE (Early Academic Gifted Learning Experience): A Program for Gifted and Talented Students (Grades K-3)--Kindergarten Activity Booklets: Xanthus; Zhack; and Activity Pages H-Z.

    ERIC Educational Resources Information Center

    Merkoski, Kay

    Three activity booklets are presented for implementing Project EAGLE, an enrichment program for gifted and talented kindergarten children. The first activity booklet contains a poem by J. D. Evans titled "In Search of the Xanthus," which describes the search for an imaginary beast that leaves an "X" on the spot where it used to be. The second…

  11. Xanthusbase after five years expands to become Openmods

    PubMed Central

    Pratt-Szeliga, Philip C.; Skewes, Aaron D.; Yan, Jinyuan; Welch, Laura G.; Welch, Roy D.

    2012-01-01

    Xanthusbase (http://www.xanthusbase.org), a model organism database for the bacterium Myxococcus xanthus, functions as a collaborative information repository based on Wikipedia principles. It was created more than 5 years ago to serve as a cost-effective reference database for M. xanthus researchers, an education tool for undergraduate students to learn about genome annotation, and a means for the community of researchers to collaboratively improve their organism’s annotation. We have achieved several goals and are seeking creative solutions to ongoing challenges. Along the way we have made several important improvements to Xanthusbase related to stability, security and usability. Most importantly, we have designed and implemented an installer that enables other microbial model organism communities to use it as a MOD. This version, called Openmods, has already been used to create Xenorhabdusbase (http://xenorhabdusbase.bact.wisc.edu), Caulobacterbase (http://caulobacterbase.bsd.uchicago.edu) and soon Bdellovibriobase. PMID:22116063

  12. In Vitro Efficacy of Myxococcus fulvus ANSM068 to Biotransform Aflatoxin B1

    PubMed Central

    Guan, Shu; Zhao, Lihong; Ma, Qiugang; Zhou, Ting; Wang, Ning; Hu, Xinxu; Ji, Cheng

    2010-01-01

    Aflatoxin B1 (AFB1) is commonly found in cereals and animal feeds and causes a significant threat to the food industry and animal production. Several microbial isolates with high AFB1 transformation ability have been identified in our previous studies. The aim of this research was to characterize one of those isolates, Myxococcus fulvus ANSM068, and to explore its biotransformation mechanism. The bacterial isolate of M. fulvus ANSM068, isolated from deer feces, was able to transform AFB1 by 80.7% in liquid VY/2 medium after incubation at 30 °C for 72 h. The supernatant of the bacterial culture was more effective in transforming AFB1 as compared to the cells alone and the cell extract. The transformation activity was significantly reduced and eradicated after the culture supernatant was treated with proteinase K, proteinase K plus SDS and heating. Culture conditions, including nitrogen source, initial pH and incubation temperature were evaluated for an optimal AFB1 transformation. Liquid chromatography mass spectrometry (LCMS) analyses showed that AFB1 was transformed to a structurally different compound. Infrared analysis (IR) indicated that the lactone ring on the AFB1 molecule was modified by the culture supernatant. Chromatographies on DEAE-Ion exchange and Sephadex-Molecular sieve and SDS-PAGE electrophoresis were used to determine active components from the culture supernatant, indicating that enzyme(s) were responsible for the AFB1 biotransformation. This is the first report on AFB1 transformation by a strain of myxobacteria through enzymatic reaction(s). PMID:21152320

  13. Single Bacterium Detection Using Sers

    NASA Astrophysics Data System (ADS)

    Gonchukov, S. A.; Baikova, T. V.; Alushin, M. V.; Svistunova, T. S.; Minaeva, S. A.; Ionin, A. A.; Kudryashov, S. I.; Saraeva, I. N.; Zayarny, D. A.

    2016-02-01

    This work is devoted to the study of a single Staphylococcus aureus bacterium detection using surface-enhanced Raman spectroscopy (SERS) and resonant Raman spectroscopy (RS). It was shown that SERS allows increasing sensitivity of predominantly low frequency lines connected with the vibrations of Amide, Proteins and DNA. At the same time the lines of carotenoids inherent to this kind of bacterium are well-detected due to the resonance Raman scattering mechanism. The reproducibility and stability of Raman spectra strongly depend on the characteristics of nanostructured substrate, and molecular structure and size of the tested biological object.

  14. Positively Frequency-Dependent Interference Competition Maintains Diversity and Pervades a Natural Population of Cooperative Microbes.

    PubMed

    Rendueles, Olaya; Amherd, Michaela; Velicer, Gregory J

    2015-06-29

    Positively frequency-dependent selection is predicted from theory to promote diversity in patchily structured populations and communities, but empirical support for this prediction has been lacking. Here, we investigate frequency-dependent selection among isolates from a local natural population of the highly social bacterium Myxococcus xanthus. Upon starvation, closely related cells of M. xanthus cooperate to construct multicellular fruiting bodies, yet recently diverged genotypes co-residing in a local soil population often antagonize one another during fruiting-body development in mixed groups. In the experiments reported here, both fitness per se and strong forms of interference competition exhibit pervasive and strong positive frequency dependence (PFD) among many isolates from a centimeter-scale soil population of M. xanthus. All strains that compete poorly at intermediate frequency are shown to be competitively dominant at high frequency in most genotype pairings during both growth and development, and strongly so. Interference competition is often lethal and appears to be contact dependent rather than mediated by diffusible compounds. Finally, we experimentally demonstrate that positively frequency-dependent selection maintains diversity when genotype frequencies vary patchily in structured populations. These results suggest that PFD contributes to the high levels of local diversity found among M. xanthus social groups in natural soil populations by reinforcing social barriers to cross-territory invasion and thereby also promotes high within-group relatedness. More broadly, our results suggest that potential roles of PFD in maintaining patchily distributed diversity should be investigated more extensively in other species. PMID:26051889

  15. Novel Waddlia Intracellular Bacterium in Artibeus intermedius Fruit Bats, Mexico

    PubMed Central

    Pierlé, Sebastián Aguilar; Morales, Cirani Obregón; Martínez, Leonardo Perea; Ceballos, Nidia Aréchiga; Rivero, Juan José Pérez; Díaz, Osvaldo López; Brayton, Kelly A.

    2015-01-01

    An intracellular bacterium was isolated from fruit bats (Artibeus intermedius) in Cocoyoc, Mexico. The bacterium caused severe lesions in the lungs and spleens of bats and intracytoplasmic vacuoles in cell cultures. Sequence analyses showed it is related to Waddlia spp. (order Chlamydiales). We propose to call this bacterium Waddlia cocoyoc. PMID:26583968

  16. Novel Waddlia Intracellular Bacterium in Artibeus intermedius Fruit Bats, Mexico.

    PubMed

    Pierlé, Sebastián Aguilar; Morales, Cirani Obregón; Martínez, Leonardo Perea; Ceballos, Nidia Aréchiga; Rivero, Juan José Pérez; Díaz, Osvaldo López; Brayton, Kelly A; Setién, Alvaro Aguilar

    2015-12-01

    An intracellular bacterium was isolated from fruit bats (Artibeus intermedius) in Cocoyoc, Mexico. The bacterium caused severe lesions in the lungs and spleens of bats and intracytoplasmic vacuoles in cell cultures. Sequence analyses showed it is related to Waddlia spp. (order Chlamydiales). We propose to call this bacterium Waddlia cocoyoc. PMID:26583968

  17. Bacteria that glide with helical tracks

    PubMed Central

    Nan, Beiyan; McBride, Mark J.; Chen, Jing; Zusman, David R.; Oster, George

    2014-01-01

    Many bacteria glide smoothly on surfaces, but with no discernable propulsive organelles on their surface. Recent experiments with Myxococcus xanthus and Flavobacterium johnsoniae show that both distantly related bacterial species glide utilizing proteins that move in helical tracks, albeit with significantly different motility mechanisms. Both species utilize proton motive force for movement. However, the motors that power gliding in M. xanthus have been identified, while the F. johnsoniae motors remain to be discovered. PMID:24556443

  18. Ratoon stunting disease of sugarcane: isolation of the causal bacterium.

    PubMed

    Davis, M J; Gillaspie, A G; Harris, R W; Lawson, R H

    1980-12-19

    A small coryneform bacterium was consistently isolated from sugarcane with ratoon stunting disease and shown to be the causal agent. A similar bacterium was isolated from Bermuda grass. Both strains multiplied in sugarcane and Bermuda grass, but the Bermuda grass strain did not incite the symptoms of ratoon stunting disease in sugarcane. Shoot growth in Bermuda grass was retarded by both strains. PMID:17817853

  19. Agrobacterium tumefaciens is a diazotrophic bacterium

    SciTech Connect

    Kanvinde, L.; Sastry, G.R.K. )

    1990-07-01

    This is the first report that Agrobacterium tumefaciens can fix nitrogen in a free-living condition as shown by its abilities to grown on nitrogen-free medium, reduce acetylene to ethylene, and incorporate {sup 15}N supplied as {sup 15}N{sub 2}. As with most other well-characterized diazotrophic bacteria, the presence of NH{sub 4}{sup +} in the medium and aerobic conditions repress nitrogen fixation by A. tumefaciens. The system requires molybdenum. No evidence for nodulation was found with pea, peanut, or soybean plants. Further understanding of the nitrogen-fixing ability of this bacterium, which has always been considered a pathogen, should cast new light on the evolution of a pathogenic versus symbiotic relationship.

  20. The chemical formula of a magnetotactic bacterium.

    PubMed

    Naresh, Mohit; Das, Sayoni; Mishra, Prashant; Mittal, Aditya

    2012-05-01

    Elucidation of the chemical logic of life is one of the grand challenges in biology, and essential to the progress of the upcoming field of synthetic biology. Treatment of microbial cells explicitly as a "chemical" species in controlled reaction (growth) environments has allowed fascinating discoveries of elemental formulae of a few species that have guided the modern views on compositions of a living cell. Application of mass and energy balances on living cells has proved to be useful in modeling of bioengineering systems, particularly in deriving optimized media compositions for growing microorganisms to maximize yields of desired bio-derived products by regulating intra-cellular metabolic networks. In this work, application of elemental mass balance during growth of Magnetospirillum gryphiswaldense in bioreactors has resulted in the discovery of the chemical formula of the magnetotactic bacterium. By developing a stoichiometric equation characterizing the formation of a magnetotactic bacterial cell, coupled with rigorous experimental measurements and robust calculations, we report the elemental formula of M. gryphiswaldense cell as CH(2.06)O(0.13)N(0.28)Fe(1.74×10(-3)). Remarkably, we find that iron metabolism during growth of this magnetotactic bacterium is much more correlated individually with carbon and nitrogen, compared to carbon and nitrogen with each other, indicating that iron serves more as a nutrient during bacterial growth rather than just a mineral. Magnetotactic bacteria have not only invoked some interest in the field of astrobiology for the last two decades, but are also prokaryotes having the unique ability of synthesizing membrane bound intracellular organelles. Our findings on these unique prokaryotes are a strong addition to the limited repertoire, of elemental compositions of living cells, aimed at exploring the chemical logic of life. PMID:22170293

  1. Characterizations of intracellular arsenic in a bacterium

    NASA Astrophysics Data System (ADS)

    Wolfe-Simon, F.; Yannone, S. M.; Tainer, J. A.

    2011-12-01

    Life requires a key set of chemical elements to sustain growth. Yet, a growing body of literature suggests that microbes can alter their nutritional requirements based on the availability of these chemical elements. Under limiting conditions for one element microbes have been shown to utilize a variety of other elements to serve similar functions often (but not always) in similar molecular structures. Well-characterized elemental exchanges include manganese for iron, tungsten for molybdenum and sulfur for phosphorus or oxygen. These exchanges can be found in a wide variety of biomolecules ranging from protein to lipids and DNA. Recent evidence suggested that arsenic, as arsenate or As(V), was taken up and incorporated into the cellular material of the bacterium GFAJ-1. The evidence was interpreted to support As(V) acting in an analogous role to phosphate. We will therefore discuss our ongoing efforts to characterize intracellular arsenate and how it may partition among the cellular fractions of the microbial isolate GFAJ-1 when exposed to As(V) in the presence of various levels of phosphate. Under high As(V) conditions, cells express a dramatically different proteome than when grown given only phosphate. Ongoing studies on the diversity and potential role of proteins and metabolites produced in the presence of As(V) will be reported. These investigations promise to inform the role and additional metabolic potential for As in biology. Arsenic assimilation into biomolecules contributes to the expanding set of chemical elements utilized by microbes in unusual environmental niches.

  2. Detection of Salmonella bacterium in drinking water using microring resonator.

    PubMed

    Bahadoran, Mahdi; Noorden, Ahmad Fakhrurrazi Ahmad; Mohajer, Faeze Sadat; Abd Mubin, Mohamad Helmi; Chaudhary, Kashif; Jalil, Muhammad Arif; Ali, Jalil; Yupapin, Preecha

    2016-01-01

    A new microring resonator system is proposed for the detection of the Salmonella bacterium in drinking water, which is made up of SiO2-TiO2 waveguide embedded inside thin film layer of the flagellin. The change in refractive index due to the binding of the Salmonella bacterium with flagellin layer causes a shift in the output signal wavelength and the variation in through and drop port's intensities, which leads to the detection of Salmonella bacterium in drinking water. The sensitivity of proposed sensor for detecting of Salmonella bacterium in water solution is 149 nm/RIU and the limit of detection is 7 × 10(-4)RIU. PMID:25133457

  3. Genome Sequence of the Soil Bacterium Janthinobacterium sp. KBS0711.

    PubMed

    Shoemaker, William R; Muscarella, Mario E; Lennon, Jay T

    2015-01-01

    We present a draft genome of Janthinobacterium sp. KBS0711 that was isolated from agricultural soil. The genome provides insight into the ecological strategies of this bacterium in free-living and host-associated environments. PMID:26089434

  4. Genome Sequence of the Soil Bacterium Janthinobacterium sp. KBS0711

    PubMed Central

    Shoemaker, William R.; Muscarella, Mario E.

    2015-01-01

    We present a draft genome of Janthinobacterium sp. KBS0711 that was isolated from agricultural soil. The genome provides insight into the ecological strategies of this bacterium in free-living and host-associated environments. PMID:26089434

  5. Taxonomic characterization of the cellulose-degrading bacterium NCIB 10462

    SciTech Connect

    Dees, C.; Ringleberg, D.; Scott, T.C.; Phelps, T.

    1994-06-01

    The gram negative cellulase-producing bacterium NCIB 10462 has been previously named Pseudomonas fluorescens subsp. or var. cellulosa. Since there is renewed interest in cellulose-degrading bacteria for use in bioconversion of cellulose to chemical feed stocks and fuels, we re-examined the characteristics of this microorganism to determine its proper taxonomic characterization and to further define it`s true metabolic potential. Metabolic and physical characterization of NCIB 10462 revealed that this was an alkalophilic, non-fermentative, gram negative, oxidase positive, motile, cellulose-degrading bacterium. The aerobic substrate utilization profile of this bacterium was found to have few characteristics consistent with a classification of P. fluorescens with a very low probability match with the genus Sphingomonas. Total lipid analysis did not reveal that any sphingolipid bases are produced by this bacterium. NCIB 10462 was found to grow best aerobically but also grows well in complex media under reducing conditions. NCIB 10462 grew slowly under full anaerobic conditions on complex media but growth on cellulosic media was found only under aerobic conditions. Total fatty acid analysis (MIDI) of NCIB 10462 failed to group this bacterium with a known pseudomonas species. However, fatty acid analysis of the bacteria when grown at temperatures below 37{degrees}C suggest that the organism is a pseudomonad. Since a predominant characteristic of this bacterium is it`s ability to degrade cellulose, we suggest it be called Pseudomonas cellulosa.

  6. Pangenome Evolution in the Marine Bacterium Alteromonas

    PubMed Central

    López-Pérez, Mario; Rodriguez-Valera, Francisco

    2016-01-01

    We have examined a collection of the free-living marine bacterium Alteromonas genomes with cores diverging in average nucleotide identities ranging from 99.98% to 73.35%, i.e., from microbes that can be considered members of a natural clone (like in a clinical epidemiological outbreak) to borderline genus level. The genomes were largely syntenic allowing a precise delimitation of the core and flexible regions in each. The core was 1.4 Mb (ca. 30% of the typical strain genome size). Recombination rates along the core were high among strains belonging to the same species (37.7–83.7% of all nucleotide polymorphisms) but they decreased sharply between species (18.9–5.1%). Regarding the flexible genome, its main expansion occurred within the boundaries of the species, i.e., strains of the same species already have a large and diverse flexible genome. Flexible regions occupy mostly fixed genomic locations. Four large genomic islands are involved in the synthesis of strain-specific glycosydic receptors that we have called glycotypes. These genomic regions are exchanged by homologous recombination within and between species and there is evidence for their import from distant taxonomic units (other genera within the family). In addition, several hotspots for integration of gene cassettes by illegitimate recombination are distributed throughout the genome. They code for features that give each clone specific properties to interact with their ecological niche and must flow fast throughout the whole genus as they are found, with nearly identical sequences, in different species. Models for the generation of this genomic diversity involving phage predation are discussed. PMID:27189983

  7. Pangenome Evolution in the Marine Bacterium Alteromonas.

    PubMed

    López-Pérez, Mario; Rodriguez-Valera, Francisco

    2016-01-01

    We have examined a collection of the free-living marine bacterium Alteromonas genomes with cores diverging in average nucleotide identities ranging from 99.98% to 73.35%, i.e., from microbes that can be considered members of a natural clone (like in a clinical epidemiological outbreak) to borderline genus level. The genomes were largely syntenic allowing a precise delimitation of the core and flexible regions in each. The core was 1.4 Mb (ca. 30% of the typical strain genome size). Recombination rates along the core were high among strains belonging to the same species (37.7-83.7% of all nucleotide polymorphisms) but they decreased sharply between species (18.9-5.1%). Regarding the flexible genome, its main expansion occurred within the boundaries of the species, i.e., strains of the same species already have a large and diverse flexible genome. Flexible regions occupy mostly fixed genomic locations. Four large genomic islands are involved in the synthesis of strain-specific glycosydic receptors that we have called glycotypes. These genomic regions are exchanged by homologous recombination within and between species and there is evidence for their import from distant taxonomic units (other genera within the family). In addition, several hotspots for integration of gene cassettes by illegitimate recombination are distributed throughout the genome. They code for features that give each clone specific properties to interact with their ecological niche and must flow fast throughout the whole genus as they are found, with nearly identical sequences, in different species. Models for the generation of this genomic diversity involving phage predation are discussed. PMID:27189983

  8. Bacterially mediated mineralization of vaterite

    NASA Astrophysics Data System (ADS)

    Rodriguez-Navarro, Carlos; Jimenez-Lopez, Concepcion; Rodriguez-Navarro, Alejandro; Gonzalez-Muñoz, Maria Teresa; Rodriguez-Gallego, Manuel

    2007-03-01

    Myxococcus xanthus, a common soil bacterium, plays an active role in the formation of spheroidal vaterite. Bacterial production of CO 2 and NH 3 and the transformation of the NH 3 to NH4+ and OH -, thus increasing solution pH and carbonate alkalinity, set the physicochemical conditions (high supersaturation) leading to vaterite precipitation in the microenvironment around cells, and directly onto the surface of bacterial cells. In the latter case, fossilization of bacteria occurs. Vaterite crystals formed by aggregation of oriented nanocrystals with c-axis normal to the bacterial cell-wall, or to the core of the spherulite when bacteria were not encapsulated. While preferred orientation of vaterite c-axis appears to be determined by electrostatic affinity (ionotropic effect) between vaterite crystal (0001) planes and the negatively charged functional groups of organic molecules on the bacterium cell-wall or on extracellular polymeric substances (EPS), analysis of the changes in the culture medium chemistry as well as high resolution transmission electron microscopy (HRTEM) observations point to polymorph selection by physicochemical (kinetic) factors (high supersaturation) and stabilization by organics, both connected with bacterial activity. The latter is in agreement with inorganic precipitation of vaterite induced by NH 3 and CO 2 addition in the protein-rich sterile culture medium. Our results as well as recent studies on vaterite precipitation in the presence of different types of bacteria suggest that bacterially mediated vaterite precipitation is not strain-specific, and could be more common than previously thought.

  9. Myxobacteria: Moving, Killing, Feeding, and Surviving Together.

    PubMed

    Muñoz-Dorado, José; Marcos-Torres, Francisco J; García-Bravo, Elena; Moraleda-Muñoz, Aurelio; Pérez, Juana

    2016-01-01

    Myxococcus xanthus, like other myxobacteria, is a social bacterium that moves and feeds cooperatively in predatory groups. On surfaces, rod-shaped vegetative cells move in search of the prey in a coordinated manner, forming dynamic multicellular groups referred to as swarms. Within the swarms, cells interact with one another and use two separate locomotion systems. Adventurous motility, which drives the movement of individual cells, is associated with the secretion of slime that forms trails at the leading edge of the swarms. It has been proposed that cellular traffic along these trails contributes to M. xanthus social behavior via stigmergic regulation. However, most of the cells travel in groups by using social motility, which is cell contact-dependent and requires a large number of individuals. Exopolysaccharides and the retraction of type IV pili at alternate poles of the cells are the engines associated with social motility. When the swarms encounter prey, the population of M. xanthus lyses and takes up nutrients from nearby cells. This cooperative and highly density-dependent feeding behavior has the advantage that the pool of hydrolytic enzymes and other secondary metabolites secreted by the entire group is shared by the community to optimize the use of the degradation products. This multicellular behavior is especially observed in the absence of nutrients. In this condition, M. xanthus swarms have the ability to organize the gliding movements of 1000s of rods, synchronizing rippling waves of oscillating cells, to form macroscopic fruiting bodies, with three subpopulations of cells showing division of labor. A small fraction of cells either develop into resistant myxospores or remain as peripheral rods, while the majority of cells die, probably to provide nutrients to allow aggregation and spore differentiation. Sporulation within multicellular fruiting bodies has the benefit of enabling survival in hostile environments, and increases germination and growth

  10. Myxobacteria: Moving, Killing, Feeding, and Surviving Together

    PubMed Central

    Muñoz-Dorado, José; Marcos-Torres, Francisco J.; García-Bravo, Elena; Moraleda-Muñoz, Aurelio; Pérez, Juana

    2016-01-01

    Myxococcus xanthus, like other myxobacteria, is a social bacterium that moves and feeds cooperatively in predatory groups. On surfaces, rod-shaped vegetative cells move in search of the prey in a coordinated manner, forming dynamic multicellular groups referred to as swarms. Within the swarms, cells interact with one another and use two separate locomotion systems. Adventurous motility, which drives the movement of individual cells, is associated with the secretion of slime that forms trails at the leading edge of the swarms. It has been proposed that cellular traffic along these trails contributes to M. xanthus social behavior via stigmergic regulation. However, most of the cells travel in groups by using social motility, which is cell contact-dependent and requires a large number of individuals. Exopolysaccharides and the retraction of type IV pili at alternate poles of the cells are the engines associated with social motility. When the swarms encounter prey, the population of M. xanthus lyses and takes up nutrients from nearby cells. This cooperative and highly density-dependent feeding behavior has the advantage that the pool of hydrolytic enzymes and other secondary metabolites secreted by the entire group is shared by the community to optimize the use of the degradation products. This multicellular behavior is especially observed in the absence of nutrients. In this condition, M. xanthus swarms have the ability to organize the gliding movements of 1000s of rods, synchronizing rippling waves of oscillating cells, to form macroscopic fruiting bodies, with three subpopulations of cells showing division of labor. A small fraction of cells either develop into resistant myxospores or remain as peripheral rods, while the majority of cells die, probably to provide nutrients to allow aggregation and spore differentiation. Sporulation within multicellular fruiting bodies has the benefit of enabling survival in hostile environments, and increases germination and growth

  11. Hydrogen Production by the Thermophilic Bacterium Thermotoga neapolitana.

    PubMed

    Pradhan, Nirakar; Dipasquale, Laura; d'Ippolito, Giuliana; Panico, Antonio; Lens, Piet N L; Esposito, Giovanni; Fontana, Angelo

    2015-01-01

    As the only fuel that is not chemically bound to carbon, hydrogen has gained interest as an energy carrier to face the current environmental issues of greenhouse gas emissions and to substitute the depleting non-renewable reserves. In the last years, there has been a significant increase in the number of publications about the bacterium Thermotoga neapolitana that is responsible for production yields of H2 that are among the highest achievements reported in the literature. Here we present an extensive overview of the most recent studies on this hyperthermophilic bacterium together with a critical discussion of the potential of fermentative production by this bacterium. The review article is organized into sections focused on biochemical, microbiological and technical issues, including the effect of substrate, reactor type, gas sparging, temperature, pH, hydraulic retention time and organic loading parameters on rate and yield of gas production. PMID:26053393

  12. Hydrogen Production by the Thermophilic Bacterium Thermotoga neapolitana

    PubMed Central

    Pradhan, Nirakar; Dipasquale, Laura; d’Ippolito, Giuliana; Panico, Antonio; Lens, Piet N. L.; Esposito, Giovanni; Fontana, Angelo

    2015-01-01

    As the only fuel that is not chemically bound to carbon, hydrogen has gained interest as an energy carrier to face the current environmental issues of greenhouse gas emissions and to substitute the depleting non-renewable reserves. In the last years, there has been a significant increase in the number of publications about the bacterium Thermotoga neapolitana that is responsible for production yields of H2 that are among the highest achievements reported in the literature. Here we present an extensive overview of the most recent studies on this hyperthermophilic bacterium together with a critical discussion of the potential of fermentative production by this bacterium. The review article is organized into sections focused on biochemical, microbiological and technical issues, including the effect of substrate, reactor type, gas sparging, temperature, pH, hydraulic retention time and organic loading parameters on rate and yield of gas production. PMID:26053393

  13. Extreme Ionizing-Radiation-Resistant Bacterium

    NASA Technical Reports Server (NTRS)

    Vaishampayan, Parag A.; Venkateswaran, Kasthuri J.; Schwendner, Petra

    2013-01-01

    potential for transfer, and subsequent proliferation, on another solar body such as Mars and Europa. These organisms are more likely to escape planetary protection assays, which only take into account presence of spores. Hence, presences of extreme radiation-resistant Deinococcus in the cleanroom facility where spacecraft are assembled pose a serious risk for integrity of life-detection missions. The microorganism described herein was isolated from the surfaces of the cleanroom facility in which the Phoenix Lander was assembled. The isolated bacterial strain was subjected to a comprehensive polyphasic analysis to characterize its taxonomic position. This bacterium exhibits very low 16SrRNA similarity with any other environmental isolate reported to date. Both phenotypic and phylogenetic analyses clearly indicate that this isolate belongs to the genus Deinococcus and represents a novel species. The name Deinococcus phoenicis was proposed after the Phoenix spacecraft, which was undergoing assembly, testing, and launch operations in the spacecraft assembly facility at the time of isolation. D. phoenicis cells exhibited higher resistance to ionizing radiation (cobalt-60; 14 kGy) than the cells of the D. radiodurans (5 kGy). Thus, it is in the best interest of NASA to thoroughly characterize this organism, which will further assess in determining the potential for forward contamination. Upon the completion of genetic and physiological characteristics of D. phoenicis, it will be added to a planetary protection database to be able to further model and predict the probability of forward contamination.

  14. Extreme Ionizing-Radiation-Resistant Bacterium

    NASA Technical Reports Server (NTRS)

    Vaishampayan, Parag A.; Venkateswaran, Kasthuri J.; Schwendner, Petra

    2012-01-01

    potential for transfer, and subsequent proliferation, on another solar body such as Mars and Europa. These organisms are more likely to escape planetary protection assays, which only take into account presence of spores. Hence, presences of extreme radiation-resistant Deinococcus in the cleanroom facility where spacecraft are assembled pose a serious risk for integrity of life-detection missions. The microorganism described herein was isolated from the surfaces of the cleanroom facility in which the Phoenix Lander was assembled. The isolated bacterial strain was subjected to a comprehensive polyphasic analysis to characterize its taxonomic position. This bacterium exhibits very low 16SrRNA similarity with any other environmental isolate reported to date. Both phenotypic and phylogenetic analyses clearly indicate that this isolate belongs to the genus Deinococcus and represents a novel species. The name Deinococcus phoenicis was proposed after the Phoenix spacecraft, which was undergoing assembly, testing, and launch operations in the spacecraft assembly facility at the time of isolation. D. phoenicis cells exhibited higher resistance to ionizing radiation (cobalt-60; 14 kGy) than the cells of the D. radiodurans (5 kGy). Thus, it is in the best interest of NASA to thoroughly characterize this organism, which will further assess in determining the potential for forward contamination. Upon the completion of genetic and physiological characteristics of D. phoenicis, it will be added to a planetary protection database to be able to further model and predict the probability of forward contamination.

  15. Microcalorimetric Measurements of Glucose Metabolism by Marine Bacterium Vibrio alginolyticus

    PubMed Central

    Gordon, Andrew S.; Millero, Frank J.; Gerchakov, Sol M.

    1982-01-01

    Microcalorimetric measurements of heat production from glucose by Vibrio alginolyticus were made to assess the viability of calorimetry as a technique for studying the metabolism of marine bacteria at organic nutrient concentrations found in marine waters. The results show that the metabolism of glucose by this bacterium can be measured by calorimetry at submicromolar concentrations. A linear correlation between glucose concentration and total heat production was observed over a concentration range of 8 mM to 0.35 μM. It is suggested that these data indicate a constant efficiency of metabolism for this bacterium over the wide range of glucose concentrations studied. PMID:16346131

  16. Uncovering the Mystery of Gliding Motility in the Myxobacteria

    PubMed Central

    Nan, Beiyan; Zusman, David R.

    2012-01-01

    Bacterial gliding motility is the smooth movement of cells on solid surfaces unaided by flagella or pili. Many diverse groups of bacteria exhibit gliding, but the mechanism of gliding motility has remained a mystery since it was first observed more than a century ago. Recent studies on the motility of Myxococcus xanthus, a soil myxobacterium, suggest a likely mechanism for gliding in this organism. About forty M. xanthus genes were shown to be involved in gliding motility, and some of their protein products were labeled and localized within cells. These studies suggest that gliding motility in M. xanthus involves large multiprotein structural complexes, regulatory proteins, and cytoskeletal filaments. In this review, we summarize recent experiments that provide the basis for this emerging view of M. xanthus motility. We also discuss alternative models for gliding. PMID:21910630

  17. Draft Genome Sequence of Oral Bacterium Streptococcus mutans JH1140

    PubMed Central

    Escano, Jerome; Deng, Peng; Lu, Shi-En

    2016-01-01

    Streptococcus mutans JH1140 is an oral bacterium known to produce the bacteriocin mutacin 1140, and the strain has been genetically engineered to combat dental caries. Here, we report the 2.0-Mb draft genome of S. mutans JH1140. This genome provides new insights into the strain’s superior colonization properties and its utility in replacement therapy. PMID:27257196

  18. Complete Genome of the Cellulolytic Ruminal Bacterium Ruminococcus albus 7

    SciTech Connect

    Suen, Garret; Stevenson, David M; Bruce, David; Chertkov, Olga; Copeland, A; Cheng, Jan-Fang; Detter, J. Chris; Goodwin, Lynne A.; Han, Cliff; Hauser, Loren John; Ivanova, N; Kyrpides, Nikos C; Land, Miriam L; Lapidus, Alla L.; Lucas, Susan; Ovchinnikova, Galina; Pitluck, Sam; Tapia, Roxanne; Woyke, Tanja; Boyum, Julie; Mead, David; Weimer, Paul J

    2011-01-01

    Ruminococcus albus 7 is a highly cellulolytic ruminal bacterium that is a member of the phylum Firmicutes. Here, we describe the complete genome of this microbe. This genome will be useful for rumen microbiology and cellulosome biology and in biofuel production, as one of its major fermentation products is ethanol.

  19. Complete genome of the cellulolytic ruminal bacterium Ruminococcus albus 7

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Ruminococcus albus 7 is a highly cellulolytic rumen bacterium that is a member of the phylum Firmicutes. Here, we describe the complete genome for this microbe. This genome will be useful for rumen microbiology, cellulosome biology, and in biofuel production, as one of its major fermentation product...

  20. Draft Genome Sequence of Oral Bacterium Streptococcus mutans JH1140.

    PubMed

    Escano, Jerome; Deng, Peng; Lu, Shi-En; Smith, Lief

    2016-01-01

    Streptococcus mutans JH1140 is an oral bacterium known to produce the bacteriocin mutacin 1140, and the strain has been genetically engineered to combat dental caries. Here, we report the 2.0-Mb draft genome of S. mutans JH1140. This genome provides new insights into the strain's superior colonization properties and its utility in replacement therapy. PMID:27257196

  1. The Mosaic Genome of Anaeromyxobacter dehalogenans Strain 2CP-C Suggests an Aerobic Common Ancestor to the Delta-Proteobacteria

    PubMed Central

    Thomas, Sara H.; Wagner, Ryan D.; Arakaki, Adrian K.; Skolnick, Jeffrey; Kirby, John R.; Shimkets, Lawrence J.; Sanford, Robert A.; Löffler, Frank E.

    2008-01-01

    Anaeromyxobacter dehalogenans strain 2CP-C is a versaphilic delta-Proteobacterium distributed throughout many diverse soil and sediment environments. 16S rRNA gene phylogenetic analysis groups A. dehalogenans together with the myxobacteria, which have distinguishing characteristics including strictly aerobic metabolism, sporulation, fruiting body formation, and surface motility. Analysis of the 5.01 Mb strain 2CP-C genome substantiated that this organism is a myxobacterium but shares genotypic traits with the anaerobic majority of the delta-Proteobacteria (i.e., the Desulfuromonadales). Reflective of its respiratory versatility, strain 2CP-C possesses 68 genes coding for putative c-type cytochromes, including one gene with 40 heme binding motifs. Consistent with its relatedness to the myxobacteria, surface motility was observed in strain 2CP-C and multiple types of motility genes are present, including 28 genes for gliding, adventurous (A-) motility and 17 genes for type IV pilus-based motility (i.e., social (S-) motility) that all have homologs in Myxococcus xanthus. Although A. dehalogenans shares many metabolic traits with the anaerobic majority of the delta-Proteobacteria, strain 2CP-C grows under microaerophilic conditions and possesses detoxification systems for reactive oxygen species. Accordingly, two gene clusters coding for NADH dehydrogenase subunits and two cytochrome oxidase gene clusters in strain 2CP-C are similar to those in M. xanthus. Remarkably, strain 2CP-C possesses a third NADH dehydrogenase gene cluster and a cytochrome cbb3 oxidase gene cluster, apparently acquired through ancient horizontal gene transfer from a strictly anaerobic green sulfur bacterium. The mosaic nature of the A. dehalogenans strain 2CP-C genome suggests that the metabolically versatile, anaerobic members of the delta-Proteobacteria may have descended from aerobic ancestors with complex lifestyles. PMID:18461135

  2. Isolation of a bacterium capable of degrading peanut hull lignin

    SciTech Connect

    Kerr, T.A.; Kerr, R.D.; Benner, R.

    1983-11-01

    Thirty-seven bacterial strains capable of degrading peanut hull lignin were isolated by using four types of lignin preparations and hot-water-extracted peanut hulls. One of the isolates, tentatively identified as Arthrobacter species, was capable of utilizing all four lignin preparations as well as extracted peanut hulls as a sole source of carbon. The bacterium was also capable of degrading specifically labeled (/sup 14/C) lignin-labeled lignocellulose and (/sup 14/C)cellulose-labeled lignocellulose from the cordgrass Spartina alterniflora and could also degrade (/sup 14/C) Kraft lignin from slash pine. After 10 days of incubation with (/sup 14/C) cellulose-labeled lignocellulose or (/sup 14/C) lignin-labeled lignocellulose from S. alterniflora, the bacterium mineralized 6.5% of the polysaccharide component and 2.9% of the lignin component. (Refs. 24).

  3. A Streamlined Strategy for Biohydrogen Production with an Alkaliphilic Bacterium

    SciTech Connect

    Elias, Dwayne A; Wall, Judy D.; Mormile, Dr. Melanie R.; Begemann, Matthew B

    2012-01-01

    Biofuels are anticipated to enable a shift from fossil fuels for renewable transportation and manufacturing fuels, with biohydrogen considered attractive since it could offer the largest reduction of global carbon budgets. Currently, biohydrogen production remains inefficient and heavily fossil fuel-dependent. However, bacteria using alkali-treated biomass could streamline biofuel production while reducing costs and fossil fuel needs. An alkaliphilic bacterium, Halanaerobium strain sapolanicus, is described that is capable of biohydrogen production at levels rivaling neutrophilic strains, but at pH 11 and hypersaline conditions. H. sapolanicus ferments a variety of 5- and 6- carbon sugars derived from hemicellulose and cellulose including cellobiose, and forms the end products hydrogen and acetate. Further, it can also produce biohydrogen from switchgrass and straw pretreated at temperatures far lower than any previously reported and in solutions compatible with growth. Hence, this bacterium can potentially increase the efficiency and efficacy of biohydrogen production from renewable biomass resources.

  4. Delta8(14)-steroids in the bacterium Methylococcus capsulatus.

    PubMed Central

    Bouvier, P; Rohmer, M; Benveniste, P; Ourisson, G

    1976-01-01

    The 4,4-dimethyl and 4alpha-methyl sterols of the bacterium Methylococcus capsulatus were identified as 4,4-dimethyl- and 4alpha-methyl-5alpha-cholest-8(14)-en-3beta-ol and 4,4-dimethyl- and 4alpha-methyl-5alpha-cholesta-8(14),24-dien-3beta-ol. Sterol biosynthesis is blocked at the level of 4alpha-methyl delta8(14)-sterols. PMID:999649

  5. Thermostable purified endoglucanase from thermophilic bacterium acidothermus cellulolyticus

    DOEpatents

    Tucker, Melvin P.; Grohmann, Karel; Himmel, Michael E.; Mohagheghi, Ali

    1992-01-01

    A substantially purified high molecular weight cellulase enzyme having a molecular weight of between about 156,000 to about 203,400 daltons isolated from the bacterium Acidothermus cellulolyticus (ATCC 43068) and a method of producing it are disclosed. The enzyme is water soluble, possesses both C.sub.1 and C.sub.x types of enzymatic activity, has a high degree of stability toward heat and exhibits both a high optimum temperature activity and high inactivation characteristics.

  6. Isolation and Characterization of a Chlorinated-Pyridinol-Degrading Bacterium

    PubMed Central

    Feng, Y.; Racke, K. D.; Bollag, J.

    1997-01-01

    The isolation of a pure culture of bacteria able to use 3,5,6-trichloro-2-pyridinol (TCP) as a sole source of carbon and energy under aerobic conditions was achieved for the first time. The bacterium was identified as a Pseudomonas sp. and designated ATCC 700113. [2,6-(sup14)C]TCP degradation yielded (sup14)CO(inf2), chloride, and unidentified polar metabolites. PMID:16535719

  7. An on-bacterium flow cytometric immunoassay for protein quantification.

    PubMed

    Lan, Wen-Jun; Lan, Wei; Wang, Hai-Yan; Yan, Lei; Wang, Zhe-Li

    2013-09-01

    The polystyrene bead-based flow cytometric immunoassay has been widely reported. However, the preparation of functional polystyrene bead is still inconvenient. This study describes a simple and easy on-bacterium flow cytometric immunoassay for protein quantification, in which Staphylococcus aureus (SAC) is used as an antibody-antigen carrier to replace the polystyrene bead. The SAC beads were prepared by carboxyfluorescein diacetate succinimidyl ester (CFSE) labeling, paraformaldehyde fixation and antibody binding. Carcinoembryonic antigen (CEA) and cytokeratin-19 fragment (CYFRA 21-1) proteins were used as models in the test system. Using prepared SAC beads, biotinylated proteins, and streptavidin-phycoerythrin (SA-PE), the on-bacterium flow cytometric immunoassay was validated by quantifying CEA and CYFRA 21-1 in sample. Obtained data demonstrated a concordant result between the logarithm of the protein concentration and the logarithm of the PE mean fluorescence intensity (MFI). The limit of detection (LOD) in this immunoassay was at least 0.25 ng/ml. Precision and accuracy assessments appeared that either the relative standard deviation (R.S.D.) or the relative error (R.E.) was <10%. The comparison between this immunoassay and a polystyrene bead-based flow cytometric immunoassay showed a correlation coefficient of 0.998 for serum CEA or 0.996 for serum CYFRA 21-1. In conclusion, the on-bacterium flow cytometric immunoassay may be of use in the quantification of serum protein. PMID:23739299

  8. A Spectrum of Pleiotropic Consequences in Development Due to Changes in a Regulatory Pathway

    PubMed Central

    Escalante, Ana E.; Inouye, Sumiko; Travisano, Michael

    2012-01-01

    Regulatory evolution has frequently been proposed as the primary mechanism driving morphological evolution. This is because regulatory changes may be less likely to cause deleterious pleiotropic effects than changes in protein structure, and consequently have a higher likelihood to be beneficial. We examined the potential for mutations in trans acting regulatory elements to drive phenotypic change, and the predictability of such change. We approach these questions by the study of the phenotypic scope and size of controlled alteration in the developmental network of the bacterium Myxococcus xanthus. We perturbed the expression of a key regulatory gene (fruA) by constructing independent in-frame deletions of four trans acting regulatory loci that modify its expression. While mutants retained developmental capability, the deletions caused changes in the expression of fruA and a dramatic shortening of time required for completion of development. We found phenotypic changes in the majority of traits measured, indicating pleiotropic effects of changes in regulation. The magnitude of the change for different traits was variable but the extent of differences between the mutants and parental type were consistent with changes in fruA expression. We conclude that changes in the expression of essential regulatory regions of developmental networks may simultaneously lead to modest as well as dramatic morphological changes upon which selection may subsequently act. PMID:22937047

  9. Rapid and widespread de novo evolution of kin discrimination

    PubMed Central

    Rendueles, Olaya; Zee, Peter C.; Dinkelacker, Iris; Amherd, Michaela; Wielgoss, Sébastien; Velicer, Gregory J.

    2015-01-01

    Diverse forms of kin discrimination, broadly defined as alteration of social behavior as a function of genetic relatedness among interactants, are common among social organisms from microbes to humans. However, the evolutionary origins and causes of kin-discriminatory behavior remain largely obscure. One form of kin discrimination observed in microbes is the failure of genetically distinct colonies to merge freely upon encounter. Here, we first use natural isolates of the highly social bacterium Myxococcus xanthus to show that colony-merger incompatibilities can be strong barriers to social interaction, particularly by reducing chimerism in multicellular fruiting bodies that develop near colony-territory borders. We then use experimental laboratory populations to test hypotheses regarding the evolutionary origins of kin discrimination. We show that the generic process of adaptation, irrespective of selective environment, is sufficient to repeatedly generate kin-discriminatory behaviors between evolved populations and their common ancestor. Further, we find that kin discrimination pervasively evolves indirectly between allopatric replicate populations that adapt to the same ecological habitat and that this occurs generically in many distinct habitats. Patterns of interpopulation discrimination imply that kin discrimination phenotypes evolved via many diverse genetic mechanisms and mutation-accumulation patterns support this inference. Strong incompatibility phenotypes emerged abruptly in some populations but strengthened gradually in others. The indirect evolution of kin discrimination in an asexual microbe is analogous to the indirect evolution of reproductive incompatibility in sexual eukaryotes and linguistic incompatibility among human cultures, the commonality being indirect, noncoordinated divergence of complex systems evolving in isolation. PMID:26150498

  10. Influence of plaque-forming bacterium, Rhodobacteraceae sp. on the growth of Chlorella vulgaris.

    PubMed

    Chen, Zhangran; Zhang, Jingyan; Lei, Xueqian; Zhang, Bangzhou; Cai, Guanjing; Zhang, Huajun; Li, Yi; Zheng, Wei; Tian, Yun; Xu, Hong; Zheng, Tianling

    2014-10-01

    Experiments were conducted to find out the molecular features, infection process of a special alga plaque-forming microorganism and its potential influence on the biomass of Chlorella vulgaris during the infection process. Direct contact between the algal cell and the bacterium may be the primary steps needed for the bacterium to lyse the alga. Addition of C. vulgaris cells into f/2 medium allowed us obtain the object bacterium. The 16S rRNA gene sequence comparisons results showed that the plaque-forming bacterium kept the closest relationship with Labrenzia aggregata IAM 12614(T) at 98.90%. The existence of the bacterium could influence both the dry weight and lipid content of C. vulgaris. This study demonstrated that direct cell wall disruption of C. vulgaris by the bacterium would be a potentially effective method to utilize the biomass of microalgae. PMID:25086475

  11. Fast Neutron Irradiation of the Highly Radioresistant Bacterium Deinococcus Radiodurans

    NASA Astrophysics Data System (ADS)

    Case, Diane Louise

    Fast neutron dose survival curves were generated for the bacterium Deinococcus radiodurans, which is renowned for its unusually high resistance to gamma, x-ray, and ultraviolet radiation, but for which fast neutron response was unknown. The fast neutrons were produced by the University of Massachusetts Lowell 5.5-MV, type CN Van de Graaff accelerator through the ^7Li(p,n)^7 Be reaction by bombarding a thick metallic lithium target with a 4-MeV proton beam. The bacteria were uniformly distributed on 150-mm agar plates and were exposed to the fast neutron beam under conditions of charged particle equilibrium. The plates were subdivided into concentric rings of increasing diameter from the center to the periphery of the plate, within which the average neutron dose was calculated as the product of the precisely known neutron fluence at the average radius of the ring and the neutron energy dependent kerma factor. The neutron fluence and dose ranged from approximately 3 times 1013 n cm^ {-2} to 1 times 1012 n cm^ {-2}, and 200 kilorad to 5 kilorad, respectively, from the center to the periphery of the plate. Percent survival for Deinococcus radiodurans as a function of fast neutron dose was derived from the ability of the irradiated cells to produce visible colonies within each ring compared to that of a nonirradiated control population. The bacterium Escherichia coli B/r (CSH) was irradiated under identical conditions for comparative purposes. The survival response of Deinococcus radiodurans as a result of cumulative fast neutron exposures was also investigated. The quantification of the ability of Deinococcus radiodurans to survive cellular insult from secondary charged particles, which are produced by fast neutron interactions in biological materials, will provide valuable information about damage and repair mechanisms under extreme cellular stress, and may provide new insight into the origin of this bacterium's unprecedented radiation resistance.

  12. The terminal oxidase in the marine bacterium Pseudomonas nautica 617.

    PubMed

    Simpson, H; Denis, M; Malatesta, F

    1997-06-01

    The molecular properties of a novel membrane quinol oxidase from the marine bacterium Pseudomonas nautica 617 are presented. The protein contains 2b hemes/mole which may be distinguished by EPR spectroscopy but not by optical spectroscopy and electrochemistry. Respiration, though being cyanide insensitive, is not inhibited by carbon monoxide and oxygen reduction is carried out only half-way with production of hydrogen peroxide. The terminal oxidase represents, therefore, a unique example in the large family of terminal oxidases known up to date. PMID:9337488

  13. Triazine herbicide resistance in the photosynthetic bacterium Rhodopseudomonas sphaeroides

    SciTech Connect

    Brown, A.E.; Gilbert, C.W.; Guy, R.; Arntzen, C.J.

    1984-10-01

    The photoaffinity herbicide azidoatrazine (2-azido-4-ethylamino-6-isopropylamino-s-triazine) selectively labels the L subunit of the reaction center of the photosynthetic bacterium Rhodopseudomonas sphaeroides. Herbicide-resistant mutants retain the L subunit and have altered binding properties for methylthio- and chloro-substituted triazines as well as altered equilibrium constants for electron transfer between primary and secondary electron acceptors. We suggest that a subtle alteration in the L subunit is responsible for herbicide resistance and that the L subunit is the functional analog of the 32-kDa Q/sub B/ protein of chloroplast membranes. 42 references, 6 figures, 1 table.

  14. Factors Affecting Zebra Mussel Kill by the Bacterium Pseudomonas fluorescens

    SciTech Connect

    Daniel P. Molloy

    2004-02-24

    The specific purpose of this research project was to identify factors that affect zebra mussel kill by the bacterium Pseudomonas fluorescens. Test results obtained during this three-year project identified the following key variables as affecting mussel kill: treatment concentration, treatment duration, mussel siphoning activity, dissolved oxygen concentration, water temperature, and naturally suspended particle load. Using this latter information, the project culminated in a series of pipe tests which achieved high mussel kill inside power plants under once-through conditions using service water in artificial pipes.

  15. Intracellular iron minerals in a dissimilatory iron-reducing bacterium.

    PubMed

    Glasauer, Susan; Langley, Sean; Beveridge, Terry J

    2002-01-01

    Among prokaryotes, there are few examples of controlled mineral formation; the formation of crystalline iron oxides and sulfides [magnetite (Fe3O4) or greigite (Fe3S4)] by magnetotactic bacteria is an exception. Shewanella putrefaciens CN32, a Gram-negative, facultative anaerobic bacterium that is capable of dissimilatory iron reduction, produced microscopic intracellular grains of iron oxide minerals during growth on two-line ferrihydrite in a hydrogen-argon atmosphere. The minerals, formed at iron concentrations found in the soil and sedimentary environments where these bacteria are active, could represent an unexplored pathway for the cycling of iron by bacteria. PMID:11778045

  16. Magnetic guidance of the magnetotactic bacterium Magnetospirillum gryphiswaldense.

    PubMed

    Loehr, Johannes; Pfeiffer, Daniel; Schüler, Dirk; Fischer, Thomas M

    2016-04-21

    Magnetospirillum gryphiswaldense is a magnetotactic bacterium with a permanent magnetic moment capable of swimming using two bipolarly located flagella. In their natural environment these bacteria swim along the field lines of the homogeneous geomagnetic field in a typical run and reversal pattern and thereby create non-differentiable trajectories with sharp edges. In the current work we nevertheless achieve stable guidance along curved lines of mechanical instability by using a heterogeneous magnetic field of a garnet film. The successful guidance of the bacteria depends on the right balance between motility and the magnetic moment of the magnetosome chain. PMID:26972517

  17. Polysaccharide degradation systems of the saprophytic bacterium Cellvibrio japonicus.

    PubMed

    Gardner, Jeffrey G

    2016-07-01

    Study of recalcitrant polysaccharide degradation by bacterial systems is critical for understanding biological processes such as global carbon cycling, nutritional contributions of the human gut microbiome, and the production of renewable fuels and chemicals. One bacterium that has a robust ability to degrade polysaccharides is the Gram-negative saprophyte Cellvibrio japonicus. A bacterium with a circuitous history, C. japonicus underwent several taxonomy changes from an initially described Pseudomonas sp. Most of the enzymes described in the pre-genomics era have also been renamed. This review aims to consolidate the biochemical, structural, and genetic data published on C. japonicus and its remarkable ability to degrade cellulose, xylan, and pectin substrates. Initially, C. japonicus carbohydrate-active enzymes were studied biochemically and structurally for their novel polysaccharide binding and degradation characteristics, while more recent systems biology approaches have begun to unravel the complex regulation required for lignocellulose degradation in an environmental context. Also included is a discussion for the future of C. japonicus as a model system, with emphasis on current areas unexplored in terms of polysaccharide degradation and emerging directions for C. japonicus in both environmental and biotechnological applications. PMID:27263016

  18. Hydrogenomics of the Extremely Thermophilic Bacterium Caldicellulosiruptor saccharolyticus▿ †

    PubMed Central

    van de Werken, Harmen J. G.; Verhaart, Marcel R. A.; VanFossen, Amy L.; Willquist, Karin; Lewis, Derrick L.; Nichols, Jason D.; Goorissen, Heleen P.; Mongodin, Emmanuel F.; Nelson, Karen E.; van Niel, Ed W. J.; Stams, Alfons J. M.; Ward, Donald E.; de Vos, Willem M.; van der Oost, John; Kelly, Robert M.; Kengen, Servé W. M.

    2008-01-01

    Caldicellulosiruptor saccharolyticus is an extremely thermophilic, gram-positive anaerobe which ferments cellulose-, hemicellulose- and pectin-containing biomass to acetate, CO2, and hydrogen. Its broad substrate range, high hydrogen-producing capacity, and ability to coutilize glucose and xylose make this bacterium an attractive candidate for microbial bioenergy production. Here, the complete genome sequence of C. saccharolyticus, consisting of a 2,970,275-bp circular chromosome encoding 2,679 predicted proteins, is described. Analysis of the genome revealed that C. saccharolyticus has an extensive polysaccharide-hydrolyzing capacity for cellulose, hemicellulose, pectin, and starch, coupled to a large number of ABC transporters for monomeric and oligomeric sugar uptake. The components of the Embden-Meyerhof and nonoxidative pentose phosphate pathways are all present; however, there is no evidence that an Entner-Doudoroff pathway is present. Catabolic pathways for a range of sugars, including rhamnose, fucose, arabinose, glucuronate, fructose, and galactose, were identified. These pathways lead to the production of NADH and reduced ferredoxin. NADH and reduced ferredoxin are subsequently used by two distinct hydrogenases to generate hydrogen. Whole-genome transcriptome analysis revealed that there is significant upregulation of the glycolytic pathway and an ABC-type sugar transporter during growth on glucose and xylose, indicating that C. saccharolyticus coferments these sugars unimpeded by glucose-based catabolite repression. The capacity to simultaneously process and utilize a range of carbohydrates associated with biomass feedstocks is a highly desirable feature of this lignocellulose-utilizing, biofuel-producing bacterium. PMID:18776029

  19. Molybdate Reduction to Molybdenum Blue by an Antarctic Bacterium

    PubMed Central

    Ahmad, S. A.; Shukor, M. Y.; Shamaan, N. A.; Mac Cormack, W. P.; Syed, M. A.

    2013-01-01

    A molybdenum-reducing bacterium from Antarctica has been isolated. The bacterium converts sodium molybdate or Mo6+ to molybdenum blue (Mo-blue). Electron donors such as glucose, sucrose, fructose, and lactose supported molybdate reduction. Ammonium sulphate was the best nitrogen source for molybdate reduction. Optimal conditions for molybdate reduction were between 30 and 50 mM molybdate, between 15 and 20°C, and initial pH between 6.5 and 7.5. The Mo-blue produced had a unique absorption spectrum with a peak maximum at 865 nm and a shoulder at 710 nm. Respiratory inhibitors such as antimycin A, sodium azide, potassium cyanide, and rotenone failed to inhibit the reducing activity. The Mo-reducing enzyme was partially purified using ion exchange and gel filtration chromatography. The partially purified enzyme showed optimal pH and temperature for activity at 6.0 and 20°C, respectively. Metal ions such as cadmium, chromium, copper, silver, lead, and mercury caused more than 95% inhibition of the molybdenum-reducing activity at 0.1 mM. The isolate was tentatively identified as Pseudomonas sp. strain DRY1 based on partial 16s rDNA molecular phylogenetic assessment and the Biolog microbial identification system. The characteristics of this strain would make it very useful in bioremediation works in the polar and temperate countries. PMID:24381945

  20. Molybdate reduction to molybdenum blue by an Antarctic bacterium.

    PubMed

    Ahmad, S A; Shukor, M Y; Shamaan, N A; Mac Cormack, W P; Syed, M A

    2013-01-01

    A molybdenum-reducing bacterium from Antarctica has been isolated. The bacterium converts sodium molybdate or Mo⁶⁺ to molybdenum blue (Mo-blue). Electron donors such as glucose, sucrose, fructose, and lactose supported molybdate reduction. Ammonium sulphate was the best nitrogen source for molybdate reduction. Optimal conditions for molybdate reduction were between 30 and 50 mM molybdate, between 15 and 20°C, and initial pH between 6.5 and 7.5. The Mo-blue produced had a unique absorption spectrum with a peak maximum at 865 nm and a shoulder at 710 nm. Respiratory inhibitors such as antimycin A, sodium azide, potassium cyanide, and rotenone failed to inhibit the reducing activity. The Mo-reducing enzyme was partially purified using ion exchange and gel filtration chromatography. The partially purified enzyme showed optimal pH and temperature for activity at 6.0 and 20°C, respectively. Metal ions such as cadmium, chromium, copper, silver, lead, and mercury caused more than 95% inhibition of the molybdenum-reducing activity at 0.1 mM. The isolate was tentatively identified as Pseudomonas sp. strain DRY1 based on partial 16s rDNA molecular phylogenetic assessment and the Biolog microbial identification system. The characteristics of this strain would make it very useful in bioremediation works in the polar and temperate countries. PMID:24381945

  1. Biological Control of Meloidogyne hapla Using an Antagonistic Bacterium

    PubMed Central

    Park, Jiyeong; Seo, Yunhee; Kim, Young Ho

    2014-01-01

    We examined the efficacy of a bacterium for biocontrol of the root-knot nematode (RKN) Meloidogyne hapla in carrot (Daucus carota subsp. sativus) and tomato (Solanum lycopersicum). Among 542 bacterial isolates from various soils and plants, the highest nematode mortality was observed for treatments with isolate C1-7, which was identified as Bacillus cereus based on cultural and morphological characteristics, the Biolog program, and 16S rRNA sequencing analyses. The population density and the nematicidal activity of B. cereus C1-7 remained high until the end of culture in brain heart infusion broth, suggesting that it may have sustainable biocontrol potential. In pot experiments, the biocontrol efficacy of B. cereus C1-7 was high, showing complete inhibition of root gall or egg mass formation by RKN in carrot and tomato plants, and subsequently reducing RKN damage and suppressing nematode population growth, respectively. Light microscopy of RKN-infected carrot root tissues treated with C1-7 showed reduced formation of gall cells and fully developed giant cells, while extensive gall cells and fully mature giant cells with prominent cell wall ingrowths formed in the untreated control plants infected with RKNs. These histopathological characteristics may be the result of residual or systemic biocontrol activity of the bacterium, which may coincide with the biocontrol efficacies of nematodes in pots. These results suggest that B. cereus C1-7 can be used as a biocontrol agent for M. hapla. PMID:25289015

  2. Radiation response mechanisms of the extremely radioresistant bacterium Deinococcus radiodurans.

    PubMed

    Kobayashi, Yasuhiko; Narumi, Issay; Satoh, Katsuya; Funayama, Tomoo; Kikuchi, Masahiro; Kitayama, Shigeru; Watanabe, Hiroshi

    2004-11-01

    Effect of microgravity on recovery of bacterial cells from radiation damage was examined in IML-2, S/MM-4 and S/MM-9 experiments using the extremely radioresistant bacterium Deinococcus radiodurans. The cells were irradiated with gamma rays before the space flight and incubated on board the Space Shuttle. The survival of the wild type cells incubated in space increased compared with the ground controls, suggesting that the recovery of this bacterium from radiation damage was enhanced under the space environment. No difference was observed between the survivals of radiosensitive mutant rec30 cells incubated in space and on the ground. The amount of DNA-repair related RecA protein induced under microgravity was similar to those of ground controls, however, induction of PprA protein, product of a unique radiation-inducible gene (designated pprA) responsible for loss of radiation resistance in repair-deficient mutant, KH311, was enhanced under microgravity compared with ground controls. Recent investigation in vitro showed that PprA preferentially bound to double-stranded DNA carrying strand breaks, inhibited Escherichia coli exonuclease III activity, and stimulated the DNA end-joining reaction catalyzed by DNA ligases. These results suggest that D. radiodurans has a radiation-induced non-homologous end-joining (NHEJ) repair mechanism in which PprA plays a critical role. PMID:15858357

  3. Polysaccharide degradation systems of the saprophytic bacterium Cellvibrio japonicus

    DOE PAGESBeta

    Gardner, Jeffrey G.

    2016-06-04

    Study of recalcitrant polysaccharide degradation by bacterial systems is critical for understanding biological processes such as global carbon cycling, nutritional contributions of the human gut microbiome, and the production of renewable fuels and chemicals. One bacterium that has a robust ability to degrade polysaccharides is the Gram-negative saprophyte Cellvibrio japonicus. A bacterium with a circuitous history, C. japonicus underwent several taxonomy changes from an initially described Pseudomonas sp. Most of the enzymes described in the pre-genomics era have also been renamed. Furthermore, this review aims to consolidate the biochemical, structural, and genetic data published on C. japonicus and its remarkablemore » ability to degrade cellulose, xylan, and pectin substrates. Initially, C. japonicus carbohydrate-active enzymes were studied biochemically and structurally for their novel polysaccharide binding and degradation characteristics, while more recent systems biology approaches have begun to unravel the complex regulation required for lignocellulose degradation in an environmental context. Also included is a discussion for the future of C. japonicus as a model system, with emphasis on current areas unexplored in terms of polysaccharide degradation and emerging directions for C. japonicus in both environmental and biotechnological applications.« less

  4. Isolation and characterization of luminescent bacterium for sludge biodegradation.

    PubMed

    Zahaba, Maryam; Halmi, Mohd Izuan Effendi; Ahmad, Siti Aqlima; Shukor, Mohd Yunus; Syed, Mohd Arif

    2015-11-01

    Microtox is based on the inhibition of luminescence of the bacterium Vibrio fischeri by the toxicants. This technique has been accepted by the USEPA (United States Environmental Protection Agency) as a biomonitoring tool for remediation of toxicants such as hydrocarbon sludge. In the present study, a luminescent bacterium was isolated from yellow striped scad (Selaroides leptolepis) and was tentatively identified as Vibrio sp. isolate MZ. This aerobic isolate showed high luminescence activity in a broad range of temperature from 25 to 35 °C. In addition, optimal conditions for high bioluminescence activity in range of pH 7.5 to 8.5 and 10 gl(-1) of sodium chloride, 10 gl(-1) of peptone and 10 gl(-1) of sucrose as carbon source. Bench scale biodegradation 1% sludge (w/v) was set up and degradation was determined using gas chromatography with flame ionised detector (GC-FID). In this study, Rhodococcus sp. strain AQ5NOL2 was used to degrade the sludge. Based on the preliminary results obtained, Vibrio sp. isolate MZwas able to monitor the biodegradation of sludge. Therefore, Vibrio sp. isolate MZ has the potential to be used as a biomonitoring agent for biomonitoring of sludge biodegradation particularly in the tropical ranged environment. PMID:26688958

  5. Metabolism of threo-beta-methylmalate by a soil bacterium.

    PubMed

    Suzuki, S; Takeuchi, Y; Sasaki, K; Katsuki, H

    1976-10-01

    Studies on threo-beta-methylmalate metabolism in a soil bacterium of the genus Bacillus which can utilize threo-beta-methylmalate as a sole carbon source were carried out. When DL-threo-beta-methylmalate was incubated with a cell-free extract of the bacterium, citramalate was found to be formed. Similarly, formation of threo-beta-methylmalate from DL-citramalate was confirmed. These dicarbosylic acids were identified by gas chromatography-mass spectrometry. Examination of inducibility, substrate specificity, and cofactor requirement of the enzymes involved in the reactions showed the existence of two interconversion reactions between the threo-beta-methylmalate and citramalate. One was an interconversion reaction between L-threo-beta-methylmalate and L-citramalate via mesaconate and the other was an interconversion reaction between D-threo-beta-methylmalate and D-citramalate via citraconate. These reactions were both reversible and were catalyzed by distinct and inducible enzymes. It is suggested that the two reactions participate in the catabolism of threo-beta-methylmalate. PMID:1010849

  6. Structure and morphology of magnetite anaerobically-produced by a marine magnetotactic bacterium and a dissimilatory iron-reducing bacterium

    USGS Publications Warehouse

    Sparks, N.H.C.; Mann, S.; Bazylinski, D.A.; Lovley, D.R.; Jannasch, H.W.; Frankel, R.B.

    1990-01-01

    Intracellular crystals of magnetite synthesized by cells of the magnetotactic vibroid organism, MV-1, and extracellular crystals of magnetite produced by the non-magnetotactic dissimilatory iron-reducing bacterium strain GS-15, were examined using high-resolution transmission electron microscopy, electron diffraction and 57Fe Mo??ssbauer spectroscopy. The magnetotactic bacterium contained a single chain of approximately 10 crystals aligned along the long axis of the cell. The crystals were essentially pure stoichiometric magnetite. When viewed along the crystal long axis the particles had a hexagonal cross-section whereas side-on they appeared as rectangules or truncated rectangles of average dimension, 53 ?? 35 nm. These findings are explained in terms of a three-dimensional morphology comprising a hexagonal prism of {110} faces which are capped and truncated by {111} end faces. Electron diffraction and lattice imaging studies indicated that the particles were structurally well-defined single crystals. In contrast, magnetite particles produced by the strain, GS-15 were irregular in shape and had smaller mean dimensions (14 nm). Single crystals were imaged but these were not of high structural perfection. These results highlight the influence of intracellular control on the crystallochemical specificity of bacterial magnetites. The characterization of these crystals is important in aiding the identification of biogenic magnetic materials in paleomagnetism and in studies of sediment magnetization. ?? 1990.

  7. Draft Genome Sequence of Ensifer adhaerens M78, a Mineral-Weathering Bacterium Isolated from Soil.

    PubMed

    Wang, Yuanli; Chen, Wei; He, Linyan; Wang, Qi; Sheng, Xia-Fang

    2016-01-01

    Ensifer adhaerens M78, a bacterium isolated from soil, can weather potash feldspar and release Fe, Si, and Al from rock under nutrient-poor conditions. Here, we report the draft genome sequence of strain M78, which may facilitate a better understanding of the molecular mechanism involved in mineral weathering by the bacterium. PMID:27609930

  8. Genome Sequence of the Antarctic Psychrophile Bacterium Planococcus antarcticus DSM 14505

    PubMed Central

    Margolles, Abelardo; Gueimonde, Miguel

    2012-01-01

    Planococcus antarcticus DSM 14505 is a psychrophile bacterium that was isolated from cyanobacterial mat samples, originally collected from ponds in McMurdo, Antarctica. This orange-pigmented bacterium grows at 4°C and may possess interesting enzymatic activities at low temperatures. Here we report the first genomic sequence of P. antarcticus DSM 14505. PMID:22843594

  9. Kinetic study of trichloroethylene and toluene degradation by a bioluminescent reporter bacterium

    SciTech Connect

    Kelly, C.J.; Sanseverino, J.; Bienkowski, P.R.; Sayler, G.S.

    1995-12-31

    A constructed bioluminescent reporter bacterium, Pseudomonas putida B2, is very briefly described in this paper. The bacterium degrades toluene and trichloroethylene (TCE), and produces light in the presence of toluene. The light response is an indication of cellular viability and expression of the genes encoding toluene and TCE degrading enzymes.

  10. Near-complete genome sequence of the cellulolytic Bacterium Bacteroides (Pseudobacteroides) cellulosolvens ATCC 35603

    DOE PAGESBeta

    Dassa, Bareket; Utturkar, Sagar M.; Hurt, Richard A.; Klingeman, Dawn Marie; Keller, Martin; Xu, Jian; Reddy, Harish Kumar; Borovok, Ilya; Grinberg, Inna Rozman; Lamed, Raphael; et al

    2015-09-24

    We report the single-contig genome sequence of the anaerobic, mesophilic, cellulolytic bacterium, Bacteroides cellulosolvens. The bacterium produces a particularly elaborate cellulosome system, whereas the types of cohesin-dockerin interactions are opposite of other known cellulosome systems: cell-surface attachment is thus mediated via type-I interactions whereas enzymes are integrated via type-II interactions.

  11. FEEDING EXPERIMENTS WITH BACTERIUM PULLORUM. THE TOXICITY OF INFECTED EGGS.

    PubMed

    Rettger, L F; Hull, T G; Sturges, W S

    1916-04-01

    The problem of eradicating ovarian infection in the domestic fowl assumes still greater importance than heretofore, in the light of data recently acquired. Not only is it of great significance to eliminate the permanent carriers of Bacterium pullorum from all flocks of fowls from the standpoint of successful poultry breeding, but also because they constitute a possible source of danger to man. Eggs which harbor Bacterium pullorum in the yolk in large numbers may produce abnormal conditions, when fed, not only in young chicks, but in adult fowls, young rabbits, guinea pigs, and kittens. The toxicity for young rabbits is most pronounced, the infection usually resulting in the death of the animals. In kittens the most prominent symptoms are those of severe food-poisoning with members of the paratyphoid group of bacteria. The possibility of infected eggs causing serious disturbances in young children and in the sick and convalescent of all ages must therefore receive serious consideration. Ovarian infection of fowls is very common throughout this country. Hence, a large proportion of the marketed eggs are infected with Bacterium pullorum. When such eggs are allowed to remain in nests under broody hens, or in warm storage places, for comparatively few hours, they contain large numbers of the organism. Soft boiling, coddling, and frying on one side only do not necessarily render the yolks free from viable bacteria; therefore, eggs which have gone through these processes may, like raw eggs, be the cause of serious disturbances in persons who are particularly susceptible to such influences, and especially to infants. That no well authenticated instances of egg-poisoning of this kind are on record does not warrant the assumption that there have been no cases. The etiology of infantile stomach and intestinal disturbances is as yet too little understood; in fact, it may be said that many of these disorders have no known cause, and almost as much may be said regarding gastro

  12. Metabolic characterisation of a novel vanillylmandelate-degrading bacterium.

    PubMed

    Turner, J E; Allison, N; Fewson, C A

    1996-10-01

    A newly isolated gram-negative bacterium, possibly Brevundimonas diminuta, utilised D,L-vanillylmandelate (D,L-VMA) as a sole carbon and energy source. The organism converted D,L-VMA to vanillylglyoxylate using a soluble NAD-dependent dehydrogenase specific for D-VMA and a dye-linked, membrane-associated L-VMA dehydrogenase. Vanillylglyoxylate was further metabolised by decarboxylation, dehydrogenation and demethylation to protocatechuate. A 4,5-dioxygenase cleaved protocatechuate to 2-hydroxy-4-carboxymuconic semialdehyde. Partially purified d-VMA dehydrogenase exhibited optimal activity at 30 degrees C and pH 9.5 and had an apparent Km for D-VMA of 470 microM. Although induced by several substituted mandelates, the enzyme had a narrow substrate specificity range with virtually no activity towards D-mandelate. Such properties render the enzyme of potential use in both diagnostic and biosynthetic applications. PMID:8824148

  13. Fungal lysis by a soil bacterium fermenting cellulose.

    PubMed

    Tolonen, Andrew C; Cerisy, Tristan; El-Sayyed, Hafez; Boutard, Magali; Salanoubat, Marcel; Church, George M

    2015-08-01

    Recycling of plant biomass by a community of bacteria and fungi is fundamental to carbon flow in terrestrial ecosystems. Here we report how the plant fermenting, soil bacterium Clostridium phytofermentans enhances growth on cellulose by simultaneously lysing and consuming model fungi from soil. We investigate the mechanism of fungal lysis to show that among the dozens of different glycoside hydrolases C. phytofermentans secretes on cellulose, the most highly expressed enzymes degrade fungi rather than plant substrates. These enzymes, the GH18 Cphy1799 and Cphy1800, synergize to hydrolyse chitin, a main component of the fungal cell wall. Purified enzymes inhibit fungal growth and mutants lacking either GH18 grow normally on cellulose and other plant substrates, but have a reduced ability to hydrolyse chitinous substrates and fungal hyphae. Thus, C. phytofermentans boosts growth on cellulose by lysing fungi with its most highly expressed hydrolases, highlighting the importance of fungal interactions to the ecology of cellulolytic bacteria. PMID:24798076

  14. Characterization of the quinones in purple sulfur bacterium Thermochromatium tepidum.

    PubMed

    Kimura, Yuuka; Kawakami, Tomoaki; Yu, Long-Jiang; Yoshimura, Miku; Kobayashi, Masayuki; Wang-Otomo, Zheng-Yu

    2015-07-01

    Quinone distributions in the thermophilic purple sulfur bacterium Thermochromatium tepidum have been investigated at different levels of the photosynthetic apparatus. Here we show that, on average, the intracytoplasmic membrane contains 18 ubiquinones (UQ) and 4 menaquinones (MQ) per reaction center (RC). About one-third of the quinones are retained in the light-harvesting-reaction center core complex (LH1-RC) with a similar ratio of UQ to MQ. The numbers of quinones essentially remains unchanged during crystallization of the LH1-RC. There are 1-2 UQ and 1 MQ associated with the RC-only complex in the purified solution sample. Our results suggest that a large proportion of the quinones are confined to the core complex and at least five UQs remain invisible in the current LH1-RC crystal structure. PMID:26048701

  15. Mechanism of anaerobic degradation of triethanolamine by a homoacetogenic bacterium

    SciTech Connect

    Speranza, Giovanna . E-mail: giovanna.speranza@unimi.it; Morelli, Carlo F.; Cairoli, Paola; Mueller, Britta; Schink, Bernhard

    2006-10-20

    Triethanolamine (TEA) is converted into acetate and ammonia by a strictly anaerobic, gram-positive Acetobacterium strain LuTria3. Fermentation experiments with resting cell suspensions and specifically deuterated substrates indicate that in the acetate molecule the carboxylate and the methyl groups correspond to the alcoholic function and to its adjacent methylene group, respectively, of the 2-hydroxyethyl unit of TEA. A 1,2 shift of a hydrogen (deuterium) atom from -CH{sub 2} -O- to =N-CH{sub 2} - without exchange with the medium was observed. This fact gives evidence that a radical mechanism occurs involving the enzyme and/or coenzyme molecule as a hydrogen carrier. Such a biodegradation appears analogous to the conversion of 2-phenoxyethanol into acetate mediated by another strain of the anaerobic homoacetogenic bacterium Acetobacterium.

  16. A bacterium that degrades and assimilates poly(ethylene terephthalate).

    PubMed

    Yoshida, Shosuke; Hiraga, Kazumi; Takehana, Toshihiko; Taniguchi, Ikuo; Yamaji, Hironao; Maeda, Yasuhito; Toyohara, Kiyotsuna; Miyamoto, Kenji; Kimura, Yoshiharu; Oda, Kohei

    2016-03-11

    Poly(ethylene terephthalate) (PET) is used extensively worldwide in plastic products, and its accumulation in the environment has become a global concern. Because the ability to enzymatically degrade PET has been thought to be limited to a few fungal species, biodegradation is not yet a viable remediation or recycling strategy. By screening natural microbial communities exposed to PET in the environment, we isolated a novel bacterium, Ideonella sakaiensis 201-F6, that is able to use PET as its major energy and carbon source. When grown on PET, this strain produces two enzymes capable of hydrolyzing PET and the reaction intermediate, mono(2-hydroxyethyl) terephthalic acid. Both enzymes are required to enzymatically convert PET efficiently into its two environmentally benign monomers, terephthalic acid and ethylene glycol. PMID:26965627

  17. Isolation of a bacterium that reductively dechlorinates tetrachloroethene to ethene

    SciTech Connect

    Maymo-Gatell, X.; Chien, Yueh-tyng; Zinder, S.H.

    1997-06-06

    Tetrachloroethene is a prominent groundwater pollutant that can be reductively dechlorinated by mixed anaerobic microbial populations to the nontoxic product ethene. Strain 195, a coccoid bacterium that dechlorinates tetrachlorethene to ethene, was isolated and characterized. Growth of strain 195 with H{sub 2} and tetrachloroethene as the electron donor and acceptor pair required extracts from mixed microbial cultures. Growth of strain 195 was resistant to ampicillin and vancomycin; its cell wall did not react with a peptidoglycan-specific lectin and its ultrastructure resembled S-layers of Archaea. Analysis of the 16S ribosomal DNA sequence of strain 195 indicated that it is a eubacterium without close affiliation to any known groups. 24 refs., 4 figs., 1 tab.

  18. The domestication of the probiotic bacterium Lactobacillus acidophilus

    PubMed Central

    Bull, Matthew J.; Jolley, Keith A.; Bray, James E.; Aerts, Maarten; Vandamme, Peter; Maiden, Martin C. J.; Marchesi, Julian R.; Mahenthiralingam, Eshwar

    2014-01-01

    Lactobacillus acidophilus is a Gram-positive lactic acid bacterium that has had widespread historical use in the dairy industry and more recently as a probiotic. Although L. acidophilus has been designated as safe for human consumption, increasing commercial regulation and clinical demands for probiotic validation has resulted in a need to understand its genetic diversity. By drawing on large, well-characterised collections of lactic acid bacteria, we examined L. acidophilus isolates spanning 92 years and including multiple strains in current commercial use. Analysis of the whole genome sequence data set (34 isolate genomes) demonstrated L. acidophilus was a low diversity, monophyletic species with commercial isolates essentially identical at the sequence level. Our results indicate that commercial use has domesticated L. acidophilus with genetically stable, invariant strains being consumed globally by the human population. PMID:25425319

  19. The capacity of phototrophic sulfur bacterium Thiocapsa roseopersicina for chemosynthesis.

    PubMed

    Kondratieva, E N; Zhukov, V G; Ivanovsky, R N; Petushkova, U P; Monosov, E Z

    1976-07-01

    Purple sulfur bacterium Thiocapsa roseopersicina strain BBS requiring vitamin B12 may grow in the dark in media containing no other organic compounds. Under such conditions the cells oxidize sulfide and thiosulfate with the use of O2 and assimilate carbon dioxide. After 10--30s assimilation of NaH14CO3 about 60% of radioactivity is found in phosphorylated compounds characteristic for the reductive pentose phosphate cycle. The possibility of the function of this cycle in the dark in the presence of O2 is confirmed by the capacity of cells grown under such conditions to synthesize ribulose-1,5-diphosphate carboxylase. All this evidence suggests the ability of T. roseopersicina to change from phototrophy to aerobic chemolithoautotrophy. PMID:942280

  20. Genome analysis of the Anerobic Thermohalophilic bacterium Halothermothrix orenii

    SciTech Connect

    Mavromatis, Konstantinos; Ivanova, Natalia; Anderson, Iain; Lykidis, Athanasios; Hooper, Sean D.; Sun, Hui; Kunin, Victor; Lapidus, Alla; Hugenholtz, Philip; Patel, Bharat; Kyrpides, Nikos C.

    2008-11-03

    Halothermothirx orenii is a strictly anaerobic thermohalophilic bacterium isolated from sediment of a Tunisian salt lake. It belongs to the order Halanaerobiales in the phylum Firmicutes. The complete sequence revealed that the genome consists of one circular chromosome of 2578146 bps encoding 2451 predicted genes. This is the first genome sequence of an organism belonging to the Haloanaerobiales. Features of both Gram positive and Gram negative bacteria were identified with the presence of both a sporulating mechanism typical of Firmicutes and a characteristic Gram negative lipopolysaccharide being the most prominent. Protein sequence analyses and metabolic reconstruction reveal a unique combination of strategies for thermophilic and halophilic adaptation. H. orenii can serve as a model organism for the study of the evolution of the Gram negative phenotype as well as the adaptation under thermohalophilic conditions and the development of biotechnological applications under conditions that require high temperatures and high salt concentrations.

  1. Identification and comparative analysis of microRNAs in barnyardgrass (Echinochloa crus-galli) in response to rice allelopathy.

    PubMed

    Fang, Changxun; Li, Yingzhe; Li, Chengxun; Li, Biliang; Ren, Yongjie; Zheng, Haiping; Zeng, Xiaomei; Shen, Lihua; Lin, Wenxiong

    2015-07-01

    Rice allelopathy is a hot topic in the field of allelopathy, and behaviour of donor allelopathic rice has been well documented. However, few study addresses response of receiver barnyardgrass (BYG). We found that expression of miRNAs relevant to plant hormone signal transduction, nucleotide excision repair and the peroxisome proliferator-activated receptor and p53 signalling pathways was enhanced in BYG co-cultured with the allelopathic rice cultivar PI312777, the expression levels of these miRNAs in BYG plants were positively correlated with allelopathic potential of the co-cultured rice varieties. Treatment of BYG plants with rice-produced phenolic acids also increased miRNA expression in BYG, while treatment with rice-produced terpenoids had no obvious effect on miRNA expression. In the hydroponic system, the largest number of Myxococcus sp. was found in the growth medium containing rice with the highest allelopathic potential. The addition of phenolic acids in the hydroponic medium also increased the number of Myxococcus sp. More interestingly, inoculation with Myxococcus xanthus significantly increased miRNA expression in the treated BYG. Jointed treatments of ferulic acid and M. xanthus led to strongest growth inhibition of BYG. The results suggest that there exist involvement of Myxococcus sp. and mediation of miRNA expression in rice allelopathy against BYG. PMID:25438645

  2. Ecology and metabolism of the beneficial intestinal commensal bacterium Faecalibacterium prausnitzii.

    PubMed

    Miquel, Sylvie; Martín, Rebeca; Bridonneau, Chantal; Robert, Véronique; Sokol, Harry; Bermúdez-Humarán, Luis G; Thomas, Muriel; Langella, Philippe

    2014-01-01

    Faecalibacterium prausnitzii is a major commensal bacterium, and its prevalence is often decreased in conditions of intestinal dysbiosis. The phylogenic identity of this bacterium was described only recently. It is still poorly characterized, and its specific growth requirements in the human gastrointestinal tract are not known. In this review, we consider F. prausnitzii metabolism, its ecophysiology in both humans and animals, and the effects of drugs and nutrition on its population. We list important questions about this beneficial and ubiquitous commensal bacterium that it would be valuable to answer. PMID:24637606

  3. Novel Trypanosomatid-Bacterium Association: Evolution of Endosymbiosis in Action

    PubMed Central

    Kostygov, Alexei Y.; Dobáková, Eva; Grybchuk-Ieremenko, Anastasiia; Váhala, Dalibor; Maslov, Dmitri A.; Votýpka, Jan

    2016-01-01

    ABSTRACT We describe a novel symbiotic association between a kinetoplastid protist, Novymonas esmeraldas gen. nov., sp. nov., and an intracytoplasmic bacterium, “Candidatus Pandoraea novymonadis” sp. nov., discovered as a result of a broad-scale survey of insect trypanosomatid biodiversity in Ecuador. We characterize this association by describing the morphology of both organisms, as well as their interactions, and by establishing their phylogenetic affinities. Importantly, neither partner is closely related to other known organisms previously implicated in eukaryote-bacterial symbiosis. This symbiotic association seems to be relatively recent, as the host does not exert a stringent control over the number of bacteria harbored in its cytoplasm. We argue that this unique relationship may represent a suitable model for studying the initial stages of establishment of endosymbiosis between a single-cellular eukaryote and a prokaryote. Based on phylogenetic analyses, Novymonas could be considered a proxy for the insect-only ancestor of the dixenous genus Leishmania and shed light on the origin of the two-host life cycle within the subfamily Leishmaniinae. PMID:26980834

  4. High cell density cultivation of the chemolithoautotrophic bacterium Nitrosomonas europaea.

    PubMed

    Papp, Benedek; Török, Tibor; Sándor, Erzsébet; Fekete, Erzsébet; Flipphi, Michel; Karaffa, Levente

    2016-05-01

    Nitrosomonas europaea is a chemolithoautotrophic nitrifier, a gram-negative bacterium that can obtain all energy required for growth from the oxidation of ammonia to nitrite, and this may be beneficial for various biotechnological and environmental applications. However, compared to other bacteria, growth of ammonia oxidizing bacteria is very slow. A prerequisite to produce high cell density N. europaea cultures is to minimize the concentrations of inhibitory metabolic by-products. During growth on ammonia nitrite accumulates, as a consequence, N. europaea cannot grow to high cell concentrations under conventional batch conditions. Here, we show that single-vessel dialysis membrane bioreactors can be used to obtain substantially increased N. europaea biomasses and substantially reduced nitrite levels in media initially containing high amounts of the substrate. Dialysis membrane bioreactor fermentations were run in batch as well as in continuous mode. Growth was monitored with cell concentration determinations, by assessing dry cell mass and by monitoring ammonium consumption as well as nitrite formation. In addition, metabolic activity was probed with in vivo acridine orange staining. Under continuous substrate feed, the maximal cell concentration (2.79 × 10(12)/L) and maximal dry cell mass (0.895 g/L) achieved more than doubled the highest values reported for N. europaea cultivations to date. PMID:26358065

  5. Bacterium organizes hierarchical amorphous structure in microbial cellulose

    NASA Astrophysics Data System (ADS)

    Koizumi, S.; Yue, Z.; Tomita, Y.; Kondo, T.; Iwase, H.; Yamaguchi, D.; Hashimoto, T.

    2008-05-01

    A pellicle, a gel film of microbial cellulose, is a supermolecular system containing 99% of water by weight, which is closely related to an amorphous structure in it. Using ultra-small-angle neutron scattering, in order to cover over a wide range of length scales from nm to 10μm, we examined the hierarchical amorphous structure in the microbial cellulose, which is synthesized by a bacterium (Acetobacter xylinum). The microbial cellulose swollen by water shows small-angle scattering that obeys a power law q -behavior according to q-α as a function of the magnitude of the scattering vector q . The power law, determined by scattering, is attributed to a mass fractal due to the distribution of the center of mass for the crystallite (microfibril) in amorphous cellulose swollen by water. As q increases, α takes the values of 2.5, 1, and 2.35, corresponding, respectively, to a gel network composed of bundles, a bundle composed of cellulose ribbons, and concentration fluctuations in a bundle. From the mass fractal q -behavior and its length scale limits, we evaluated a volume fraction of crystallite in microbial cellulose. It was found that 90% of the cellulose bundle is occupied by amorphous cellulose containing water.

  6. Fitness correlates with the extent of cheating in a bacterium.

    PubMed

    Jiricny, N; Diggle, S P; West, S A; Evans, B A; Ballantyne, G; Ross-Gillespie, A; Griffin, A S

    2010-04-01

    There is growing awareness of the importance of cooperative behaviours in microbial communities. Empirical support for this insight comes from experiments using mutant strains, termed 'cheats', which exploit the cooperative behaviour of wild-type strains. However, little detailed work has gone into characterising the competitive dynamics of cooperative and cheating strains. We test three specific predictions about the fitness consequences of cheating to different extents by examining the production of the iron-scavenging siderophore molecule, pyoverdin, in the bacterium Pseudomonas aeruginosa. We create a collection of mutants that differ in the amount of pyoverdin that they produce (from 1% to 96% of the production of paired wild types) and demonstrate that these production levels correlate with both gene activity and the ability to bind iron. Across these mutants, we found that (1) when grown in a mixed culture with a cooperative wild-type strain, the relative fitness of a mutant is negatively correlated with the amount of pyoverdin that it produces; (2) the absolute and relative fitness of the wild-type strain in the mixed culture is positively correlated with the amount of pyoverdin that the mutant produces; and (3) when grown in a monoculture, the absolute fitness of the mutant is positively correlated with the amount of pyoverdin that it produces. Overall, we demonstrate that cooperative pyoverdin production is exploitable and illustrate how variation in a social behaviour determines fitness differently, depending on the social environment. PMID:20210835

  7. P450 enzymes from the bacterium Novosphingobium aromaticivorans.

    PubMed

    Bell, Stephen G; Wong, Luet-Lok

    2007-08-31

    Twelve of the fifteen potential P450 enzymes from the bacterium Novosphingobium aromaticivorans, which is known to degrade a wide range of aromatic hydrocarbons, have been produced via heterologous expression in Escherichia coli. The enzymes were tested for their ability to bind a range of substrates including polyaromatic hydrocarbons. While two of the enzymes were found to bind aromatic compounds (CYP108D1 and CYP203A2), the others show binding with a variety of compounds including linear alkanes (CYP153C1) and mono- and sesqui-terpenoid compounds (CYP101B1, CYP101C1, CYP101D1, CYP101D2, CYP111A1, and CYP219A1). A 2Fe-2S ferredoxin (Arx-A), which is associated with CYP101D2, was also produced. The activity of five of the P450 enzymes (CYP101B1, CYP101C1, CYP101D1, CYP101D2, and CYP111A2) was reconstituted with Arx-A and putidaredoxin reductase (of the P450cam system from Pseudomonas putida) in a Class I type electron transfer system. Preliminary characterisation of the majority of the substrate oxidation products is reported. PMID:17618912

  8. Bioconversion of methane to lactate by an obligate methanotrophic bacterium

    PubMed Central

    Henard, Calvin A.; Smith, Holly; Dowe, Nancy; Kalyuzhnaya, Marina G.; Pienkos, Philip T.; Guarnieri, Michael T.

    2016-01-01

    Methane is the second most abundant greenhouse gas (GHG), with nearly 60% of emissions derived from anthropogenic sources. Microbial conversion of methane to fuels and value-added chemicals offers a means to reduce GHG emissions, while also valorizing this otherwise squandered high-volume, high-energy gas. However, to date, advances in methane biocatalysis have been constrained by the low-productivity and limited genetic tractability of natural methane-consuming microbes. Here, leveraging recent identification of a novel, tractable methanotrophic bacterium, Methylomicrobium buryatense, we demonstrate microbial biocatalysis of methane to lactate, an industrial platform chemical. Heterologous overexpression of a Lactobacillus helveticus L-lactate dehydrogenase in M. buryatense resulted in an initial titer of 0.06 g lactate/L from methane. Cultivation in a 5 L continuously stirred tank bioreactor enabled production of 0.8 g lactate/L, representing a 13-fold improvement compared to the initial titer. The yields (0.05 g lactate/g methane) and productivity (0.008 g lactate/L/h) indicate the need and opportunity for future strain improvement. Additionally, real-time analysis of methane utilization implicated gas-to-liquid transfer and/or microbial methane consumption as process limitations. This work opens the door to develop an array of methanotrophic bacterial strain-engineering strategies currently employed for biocatalytic sugar upgrading to “green” chemicals and fuels. PMID:26902345

  9. A serine sensor for multicellularity in a bacterium

    PubMed Central

    Subramaniam, Arvind R; DeLoughery, Aaron; Bradshaw, Niels; Chen, Yun; O’Shea, Erin; Losick, Richard; Chai, Yunrong

    2013-01-01

    We report the discovery of a simple environmental sensing mechanism for biofilm formation in the bacterium Bacillus subtilis that operates without the involvement of a dedicated RNA or protein. Certain serine codons, the four TCN codons, in the gene for the biofilm repressor SinR caused a lowering of SinR levels under biofilm-inducing conditions. Synonymous substitutions of these TCN codons with AGC or AGT impaired biofilm formation and gene expression. Conversely, switching AGC or AGT to TCN codons upregulated biofilm formation. Genome-wide ribosome profiling showed that ribosome density was higher at UCN codons than at AGC or AGU during biofilm formation. Serine starvation recapitulated the effect of biofilm-inducing conditions on ribosome occupancy and SinR production. As serine is one of the first amino acids to be exhausted at the end of exponential phase growth, reduced translation speed at serine codons may be exploited by other microbes in adapting to stationary phase. DOI: http://dx.doi.org/10.7554/eLife.01501.001 PMID:24347549

  10. P450 enzymes from the bacterium Novosphingobium aromaticivorans

    SciTech Connect

    Bell, Stephen G. . E-mail: stephen.bell@chem.ox.ac.uk; Wong, Luet-Lok

    2007-08-31

    Twelve of the fifteen potential P450 enzymes from the bacterium Novosphingobium aromaticivorans, which is known to degrade a wide range of aromatic hydrocarbons, have been produced via heterologous expression in Escherichia coli. The enzymes were tested for their ability to bind a range of substrates including polyaromatic hydrocarbons. While two of the enzymes were found to bind aromatic compounds (CYP108D1 and CYP203A2), the others show binding with a variety of compounds including linear alkanes (CYP153C1) and mono- and sesqui-terpenoid compounds (CYP101B1, CYP101C1, CYP101D1, CYP101D2, CYP111A1, and CYP219A1). A 2Fe-2S ferredoxin (Arx-A), which is associated with CYP101D2, was also produced. The activity of five of the P450 enzymes (CYP101B1, CYP101C1, CYP101D1, CYP101D2, and CYP111A2) was reconstituted with Arx-A and putidaredoxin reductase (of the P450cam system from Pseudomonas putida) in a Class I type electron transfer system. Preliminary characterisation of the majority of the substrate oxidation products is reported.

  11. The acetylproteome of Gram-positive model bacterium Bacillus subtilis.

    PubMed

    Kim, Dooil; Yu, Byung Jo; Kim, Jung Ae; Lee, Yong-Jik; Choi, Soo-Geun; Kang, Sunghyun; Pan, Jae-Gu

    2013-05-01

    N(ε) -lysine acetylation, a reversible and highly regulated PTM, has been shown to occur in the model Gram-negative bacteria Escherichia coli and Salmonella enterica. Here, we extend this acetylproteome analysis to Bacillus subtilis, a model Gram-positive bacterium. Through anti-acetyllysine antibody-based immunoseparation of acetylpeptides followed by nano-HPLC/MS/MS analysis, we identified 332 unique lysine-acetylated sites on 185 proteins. These proteins are mainly involved in cellular housekeeping functions such as central metabolism and protein synthesis. Fifity-nine of the lysine-acetylated proteins showed homology with lysine-acetylated proteins previously identified in E. coli, suggesting that acetylated proteins are more conserved. Notably, acetylation was found at or near the active sites predicted by Prosite signature, including SdhA, RocA, Kbl, YwjH, and YfmT, indicating that lysine acetylation may affect their activities. In 2-amino-3-ketobutyrate CoA ligase Kbl, a class II aminotransferase, a lysine residue involved in pyridoxal phosphate attachment was found to be acetylated. This data set provides evidence for the generality of lysine acetylation in eubacteria and opens opportunities to explore the consequences of acetylation modification on the molecular physiology of B. subtilis. PMID:23468065

  12. Heavy Metal Induced Antibiotic Resistance in Bacterium LSJC7.

    PubMed

    Chen, Songcan; Li, Xiaomin; Sun, Guoxin; Zhang, Yingjiao; Su, Jianqiang; Ye, Jun

    2015-01-01

    Co-contamination of antibiotics and heavy metals prevails in the environment, and may play an important role in disseminating bacterial antibiotic resistance, but the selective effects of heavy metals on bacterial antibiotic resistance is largely unclear. To investigate this, the effects of heavy metals on antibiotic resistance were studied in a genome-sequenced bacterium, LSJC7. The results showed that the presence of arsenate, copper, and zinc were implicated in fortifying the resistance of LSJC7 towards tetracycline. The concentrations of heavy metals required to induce antibiotic resistance, i.e., the minimum heavy metal concentrations (MHCs), were far below (up to 64-fold) the minimum inhibition concentrations (MIC) of LSJC7. This finding indicates that the relatively low heavy metal levels in polluted environments and in treated humans and animals might be sufficient to induce bacterial antibiotic resistance. In addition, heavy metal induced antibiotic resistance was also observed for a combination of arsenate and chloramphenicol in LSJC7, and copper/zinc and tetracycline in antibiotic susceptible strain Escherichia coli DH5α. Overall, this study implies that heavy metal induced antibiotic resistance might be ubiquitous among various microbial species and suggests that it might play a role in the emergence and spread of antibiotic resistance in metal and antibiotic co-contaminated environments. PMID:26426011

  13. Anaerobic degradation of toluene by a denitrifying bacterium.

    PubMed Central

    Evans, P J; Mang, D T; Kim, K S; Young, L Y

    1991-01-01

    A denitrifying bacterium, designated strain T1, that grew with toluene as the sole source of carbon under anaerobic conditions was isolated. The type of agar used in solid media and the toxicity of toluene were determinative factors in the successful isolation of strain T1. Greater than 50% of the toluene carbon was oxidized to CO2, and 29% was assimilated into biomass. The oxidation of toluene to CO2 was stoichiometrically coupled to nitrate reduction and denitrification. Strain T1 was tolerant of and grew on 3 mM toluene after a lag phase. The rate of toluene degradation was 1.8 mumol min-1 liter-1 (56 nmol min-1 mg of protein-1) in a cell suspension. Strain T1 was distinct from other bacteria that oxidize toluene anaerobically, but it may utilize a similar biochemical pathway of oxidation. In addition, o-xylene was transformed to a metabolite in the presence of toluene but did not serve as the sole source of carbon for growth of strain T1. This transformation was dependent on the degradation of toluene. Images PMID:2059037

  14. Denitrification characteristics of a marine origin psychrophilic aerobic denitrifying bacterium.

    PubMed

    Zheng, Haiyan; Liu, Ying; Sun, Guangdong; Gao, Xiyan; Zhang, Qingling; Liu, Zhipei

    2011-01-01

    A psychrophilic aerobic denitrifying bacterium, strain S1-1, was isolated from a biological aerated filter conducted for treatment of recirculating water in a marine aquaculture system. Strain S1-1 was preliminarily identified as Psychrobacter sp. based on the analysis of its 16S rRNA gene sequence, which showed 100% sequence similarity to that of Psychrobacter sp. TSBY-70. Strain S1-1 grew well either in high nitrate or high nitrite conditions with a removal of 100% nitrate or 63.50% nitrite, and the total nitrogen removal rates could reach to 46.48% and 31.89%, respectively. The results indicated that nitrate was mainly reduced in its logarithmic growth phase with a very low level accumulation of nitrite, suggesting that the aerobic denitrification process of strain S1-1 occurred mainly in this phase. The GC-MS results showed that N2O was formed as the major intermediate during the aerobic denitrifying process of strain S1-1. Finally, factors affecting the growth of strain S1-1 and its aerobic denitrifying ability were also investigated. Results showed that the optimum aerobic denitrification conditions for strain S1-1 were sodium succinate as carbon source, C/N ratio15, salinity 10 g/L NaCl, incubation temperature 20 degrees C and initial pH 6.5. PMID:22432315

  15. Mechanisms of gold biomineralization in the bacterium Cupriavidus metallidurans.

    PubMed

    Reith, Frank; Etschmann, Barbara; Grosse, Cornelia; Moors, Hugo; Benotmane, Mohammed A; Monsieurs, Pieter; Grass, Gregor; Doonan, Christian; Vogt, Stefan; Lai, Barry; Martinez-Criado, Gema; George, Graham N; Nies, Dietrich H; Mergeay, Max; Pring, Allan; Southam, Gordon; Brugger, Joël

    2009-10-20

    While the role of microorganisms as main drivers of metal mobility and mineral formation under Earth surface conditions is now widely accepted, the formation of secondary gold (Au) is commonly attributed to abiotic processes. Here we report that the biomineralization of Au nanoparticles in the metallophillic bacterium Cupriavidus metallidurans CH34 is the result of Au-regulated gene expression leading to the energy-dependent reductive precipitation of toxic Au(III)-complexes. C. metallidurans, which forms biofilms on Au grains, rapidly accumulates Au(III)-complexes from solution. Bulk and microbeam synchrotron X-ray analyses revealed that cellular Au accumulation is coupled to the formation of Au(I)-S complexes. This process promotes Au toxicity and C. metallidurans reacts by inducing oxidative stress and metal resistances gene clusters (including a Au-specific operon) to promote cellular defense. As a result, Au detoxification is mediated by a combination of efflux, reduction, and possibly methylation of Au-complexes, leading to the formation of Au(I)-C-compounds and nanoparticulate Au(0). Similar particles were observed in bacterial biofilms on Au grains, suggesting that bacteria actively contribute to the formation of Au grains in surface environments. The recognition of specific genetic responses to Au opens the way for the development of bioexploration and bioprocessing tools. PMID:19815503

  16. Heavy Metal Induced Antibiotic Resistance in Bacterium LSJC7

    PubMed Central

    Chen, Songcan; Li, Xiaomin; Sun, Guoxin; Zhang, Yingjiao; Su, Jianqiang; Ye, Jun

    2015-01-01

    Co-contamination of antibiotics and heavy metals prevails in the environment, and may play an important role in disseminating bacterial antibiotic resistance, but the selective effects of heavy metals on bacterial antibiotic resistance is largely unclear. To investigate this, the effects of heavy metals on antibiotic resistance were studied in a genome-sequenced bacterium, LSJC7. The results showed that the presence of arsenate, copper, and zinc were implicated in fortifying the resistance of LSJC7 towards tetracycline. The concentrations of heavy metals required to induce antibiotic resistance, i.e., the minimum heavy metal concentrations (MHCs), were far below (up to 64-fold) the minimum inhibition concentrations (MIC) of LSJC7. This finding indicates that the relatively low heavy metal levels in polluted environments and in treated humans and animals might be sufficient to induce bacterial antibiotic resistance. In addition, heavy metal induced antibiotic resistance was also observed for a combination of arsenate and chloramphenicol in LSJC7, and copper/zinc and tetracycline in antibiotic susceptible strain Escherichia coli DH5α. Overall, this study implies that heavy metal induced antibiotic resistance might be ubiquitous among various microbial species and suggests that it might play a role in the emergence and spread of antibiotic resistance in metal and antibiotic co-contaminated environments. PMID:26426011

  17. Yersinia ruckeri sp. nov., the redmouth (RM) bacterium

    USGS Publications Warehouse

    Ewing, W.H.; Ross, A.J.; Brenner, Don J.; Fanning, G. R.

    1978-01-01

    Cultures of the redmouth (RM) bacterium, one of the etiological agents of redmouth disease in rainbow trout (Salmo gairdneri) and certain other fishes, were characterized by means of their biochemical reactions, by deoxyribonucleic acid (DNA) hybridization, and by determination of guanine-plus-cytosine (G+C) ratios in DNA. The DNA relatedness studies confirmed the fact that the RM bacteria are members of the family Enterobacteriaceae and that they comprise a single species that is not closely related to any other species of Enterobacteriaceae. They are about 30% related to species of both Serratia and Yersinia. A comparison of the biochemical reactions of RM bacteria and serratiae indicated that there are many differences between these organisms and that biochemically the RM bacteria are most closely related to yersiniae. The G+C ratios of RM bacteria were approximated to be between 47.5 and 48.5% These values are similar to those of yersiniae but markedly different from those of serratiae. On the basis of their biochemical reactions and their G+C ratios, the RM bacteria are considered to be a new species of Yersinia, for which the name Yersinia ruckeri is proposed. Strain 2396-61 (= ATCC 29473) is designated the type strain of the species.

  18. Novel Rickettsiella Bacterium in the Leafhopper Orosius albicinctus (Hemiptera: Cicadellidae)

    PubMed Central

    Iasur-Kruh, Lilach; Weintraub, Phyllis G.; Mozes-Daube, Netta; Robinson, Wyatt E.; Perlman, Steve J.

    2013-01-01

    Bacteria in the genus Rickettsiella (Coxiellaceae), which are mainly known as arthropod pathogens, are emerging as excellent models to study transitions between mutualism and pathogenicity. The current report characterizes a novel Rickettsiella found in the leafhopper Orosius albicinctus (Hemiptera: Cicadellidae), a major vector of phytoplasma diseases in Europe and Asia. Denaturing gradient gel electrophoresis (DGGE) and pyrosequencing were used to survey the main symbionts of O. albicinctus, revealing the obligate symbionts Sulcia and Nasuia, and the facultative symbionts Arsenophonus and Wolbachia, in addition to Rickettsiella. The leafhopper Rickettsiella is allied with bacteria found in ticks. Screening O. albicinctus from the field showed that Rickettsiella is highly prevalent, with over 60% of individuals infected. A stable Rickettsiella infection was maintained in a leafhopper laboratory colony for at least 10 generations, and fluorescence microscopy localized bacteria to accessory glands of the female reproductive tract, suggesting that the bacterium is vertically transmitted. Future studies will be needed to examine how Rickettsiella affects host fitess and its ability to vector phytopathogens. PMID:23645190

  19. Bioconversion of methane to lactate by an obligate methanotrophic bacterium.

    PubMed

    Henard, Calvin A; Smith, Holly; Dowe, Nancy; Kalyuzhnaya, Marina G; Pienkos, Philip T; Guarnieri, Michael T

    2016-01-01

    Methane is the second most abundant greenhouse gas (GHG), with nearly 60% of emissions derived from anthropogenic sources. Microbial conversion of methane to fuels and value-added chemicals offers a means to reduce GHG emissions, while also valorizing this otherwise squandered high-volume, high-energy gas. However, to date, advances in methane biocatalysis have been constrained by the low-productivity and limited genetic tractability of natural methane-consuming microbes. Here, leveraging recent identification of a novel, tractable methanotrophic bacterium, Methylomicrobium buryatense, we demonstrate microbial biocatalysis of methane to lactate, an industrial platform chemical. Heterologous overexpression of a Lactobacillus helveticus L-lactate dehydrogenase in M. buryatense resulted in an initial titer of 0.06 g lactate/L from methane. Cultivation in a 5 L continuously stirred tank bioreactor enabled production of 0.8 g lactate/L, representing a 13-fold improvement compared to the initial titer. The yields (0.05 g lactate/g methane) and productivity (0.008 g lactate/L/h) indicate the need and opportunity for future strain improvement. Additionally, real-time analysis of methane utilization implicated gas-to-liquid transfer and/or microbial methane consumption as process limitations. This work opens the door to develop an array of methanotrophic bacterial strain-engineering strategies currently employed for biocatalytic sugar upgrading to "green" chemicals and fuels. PMID:26902345

  20. Mutation of bacterium Vibrio gazogenes for selective preparation of colorants.

    PubMed

    Alihosseini, Farzaneh; Lango, Jozsef; Ju, Kou-San; Hammock, Bruce D; Sun, Gang

    2010-01-01

    A novel marine bacterium strain effectively produced prodiginine type pigments. These colorants could dye wool, silk and synthetic fabrics such as polyester and polyacrylic and also show antibacterial properties against Escherichia coli and Staphylococcus aureus bacteria on the dyed products. Methyl nitrosoguanidine was used as a mutation agent to increase the genetic diversity and the production yield of the bacteria of the family of Vibrio gazogenes. The analysis of the mutated samples showed that two new main colorants as well as three previously found ones were produced. Liquid chromatography electro spray ionization mass spectrometry (LC-ESI-MS) and nuclear magnetic resonance (NMR) spectroscopic techniques were used to elucidate the structures of the newly produced colorants. Mass measurements revealed that the colorants C1, C2, C3, C4 have molecular masses of 321, 323, 351, and 295 Da. One unstable colorant C5 with molecular mass of 309 Da was detected as well. The mutated bacteria strains increased the yield of pigment production by about 81% and produced prodigiosin in 97% purity. The antibiotic activities of pure colorants are discussed as well. Based on their bio-activity and excellent dyeing capabilities, these colorants could be employed in cosmetic and textile industries. PMID:19902486

  1. Mechanisms of gold biomineralization in the bacterium Cupriavidus metallidurans

    PubMed Central

    Reith, Frank; Etschmann, Barbara; Grosse, Cornelia; Moors, Hugo; Benotmane, Mohammed A.; Monsieurs, Pieter; Grass, Gregor; Doonan, Christian; Vogt, Stefan; Lai, Barry; Martinez-Criado, Gema; George, Graham N.; Nies, Dietrich H.; Mergeay, Max; Pring, Allan; Southam, Gordon; Brugger, Joël

    2009-01-01

    While the role of microorganisms as main drivers of metal mobility and mineral formation under Earth surface conditions is now widely accepted, the formation of secondary gold (Au) is commonly attributed to abiotic processes. Here we report that the biomineralization of Au nanoparticles in the metallophillic bacterium Cupriavidus metallidurans CH34 is the result of Au-regulated gene expression leading to the energy-dependent reductive precipitation of toxic Au(III)-complexes. C. metallidurans, which forms biofilms on Au grains, rapidly accumulates Au(III)-complexes from solution. Bulk and microbeam synchrotron X-ray analyses revealed that cellular Au accumulation is coupled to the formation of Au(I)-S complexes. This process promotes Au toxicity and C. metallidurans reacts by inducing oxidative stress and metal resistances gene clusters (including a Au-specific operon) to promote cellular defense. As a result, Au detoxification is mediated by a combination of efflux, reduction, and possibly methylation of Au-complexes, leading to the formation of Au(I)-C-compounds and nanoparticulate Au0. Similar particles were observed in bacterial biofilms on Au grains, suggesting that bacteria actively contribute to the formation of Au grains in surface environments. The recognition of specific genetic responses to Au opens the way for the development of bioexploration and bioprocessing tools. PMID:19815503

  2. Bioconversion of methane to lactate by an obligate methanotrophic bacterium

    DOE PAGESBeta

    Henard, Calvin A.; Smith, Holly; Dowe, Nancy; Kalyuzhnaya, Marina G.; Pienkos, Philip T.; Guarnieri, Michael T.

    2016-02-23

    Methane is the second most abundant greenhouse gas (GHG), with nearly 60% of emissions derived from anthropogenic sources. Microbial conversion of methane to fuels and value-added chemicals offers a means to reduce GHG emissions, while also valorizing this otherwise squandered high-volume, high-energy gas. However, to date, advances in methane biocatalysis have been constrained by the low-productivity and limited genetic tractability of natural methane-consuming microbes. Here, leveraging recent identification of a novel, tractable methanotrophic bacterium, Methylomicrobium buryatense, we demonstrate microbial biocatalysis of methane to lactate, an industrial platform chemical. Heterologous overexpression of a Lactobacillus helveticus L-lactate dehydrogenase in M. buryatense resultedmore » in an initial titer of 0.06 g lactate/L from methane. Cultivation in a 5 L continuously stirred tank bioreactor enabled production of 0.8 g lactate/L, representing a 13-fold improvement compared to the initial titer. The yields (0.05 g lactate/g methane) and productivity (0.008 g lactate/L/h) indicate the need and opportunity for future strain improvement. Additionally, real-time analysis of methane utilization implicated gas-to-liquid transfer and/or microbial methane consumption as process limitations. This work opens the door to develop an array of methanotrophic bacterial strain-engineering strategies currently employed for biocatalytic sugar upgrading to “green” chemicals and fuels.« less

  3. Gracilibacillus kimchii sp. nov., a halophilic bacterium isolated from kimchi.

    PubMed

    Oh, Young Joon; Lee, Hae-Won; Lim, Seul Ki; Kwon, Min-Sung; Lee, Jieun; Jang, Ja-Young; Park, Hae Woong; Nam, Young-Do; Seo, Myung-Ji; Choi, Hak-Jong

    2016-09-01

    A novel halophilic bacterium, strain K7(T), was isolated from kimchi, a traditional Korean fermented food. The strain is Gram-positive, motile, and produces terminal endospores. The isolate is facultative aerobic and grows at salinities of 0.0-25.0% (w/v) NaCl (optimum 10-15% NaCl), pH 5.5-8.5 (optimum pH 7.0-7.5), and 15-42°C (optimum 37°C). The predominant isoprenoid quinone in the strain is menaquinone-7 and the peptidoglycan of the strain is meso-diaminopimelic acid. The major fatty acids of the strain are anteisio-C15:0, iso-C15:0, and, C16:0 (other components were < 10.0%), while the major polar lipids are diphosphatidylglycerol, phosphatidylglycerol, phosphatidylcholine, and three unidentified lipids. A phylogenetic analysis of 16S rRNA gene sequence similarity showed that the isolated strain was a cluster of the genus Gracilibacillus. High levels of gene sequence similarity were observed between strain K7(T) and Gracilibacillus orientalis XH-63(T) (96.5%), and between the present strain and Gracilibacillus xinjiangensis (96.5%). The DNA G+C content of this strain is 37.7 mol%. Based on these findings, strain K7(T) is proposed as a novel species: Gracilibacillus kimchii sp. nov. The type strain is K7(T) (KACC 18669(T); JCM 31344(T)). PMID:27572507

  4. Hydrodynamics and collective behavior of the tethered bacterium Thiovulum majus

    PubMed Central

    Petroff, Alexander; Libchaber, Albert

    2014-01-01

    The ecology and dynamics of many microbial systems, particularly in mats and soils, are shaped by how bacteria respond to evolving nutrient gradients and microenvironments. Here we show how the response of the sulfur-oxidizing bacterium Thiovulum majus to changing oxygen gradients causes cells to organize into large-scale fronts. To study this phenomenon, we develop a technique to isolate and enrich these bacteria from the environment. Using this enrichment culture, we observe the formation and dynamics of T. majus fronts in oxygen gradients. We show that these dynamics can be understood as occurring in two steps. First, chemotactic cells moving up the oxygen gradient form a front that propagates with constant velocity. We then show, through observation and mathematical analysis, that this front becomes unstable to changes in cell density. Random perturbations in cell density create oxygen gradients. The response of cells magnifies these gradients and leads to the formation of millimeter-scale fluid flows that actively pull oxygenated water through the front. We argue that this flow results from a nonlinear instability excited by stochastic fluctuations in the density of cells. Finally, we show that the dynamics by which these modes interact can be understood from the chemotactic response of cells. These results provide a mathematically tractable example of how collective phenomena in ecological systems can arise from the individual response of cells to a shared resource. PMID:24459183

  5. Molecular study on cloned endoglucanase gene from rumen bacterium.

    PubMed

    Ozkose, Emin; Akyol, Ismail; Ekinci, Mehmet Sait

    2004-01-01

    An endoglucanase gene was subcloned from anaerobic rumen bacterium Ruminococcus flavefaciens strain 17. To express endoglucanase gene in Escherichia coli and Streptococcus bovis JB1, an endoglucanase gene fragment was inserted into pVA838-based shuttle vectors. Removal of endoglucanase gene promoter and expression of endoglucanase by promoter of S. bovis JB1 alpha-amylase gene (pACMCS) was also achieved. Survival of constructs pVACMCI, pTACMC and pACMCS, which carry endoglucanase gene, and stability of endoglucanase gene in S. bovis JB1, were observed. Maximal endoglucanase activities from S. bovis JB1/pVACMCI were 2- to 3-fold higher than from E. coli/pVACMCI. Specific cell activity of E. coli/pACMCS was found to be approximately 2- to -3 fold higher than the both E. coli/pVACMCI and E. coli/pTACMC. Specific cell activity of S. bovis JB1/pACMCS was also found to be approximately 2-fold higher than the both S. bovis/pVACMCI and S. bovis JB1/pTACMC. PMID:15925902

  6. Draft Genome Sequence of the Versatile Alkane-Degrading Bacterium Aquabacterium sp. Strain NJ1

    PubMed Central

    Shiwa, Yuh; Yoshikawa, Hirofumi; Zylstra, Gerben J.

    2014-01-01

    The draft genome sequence of a soil bacterium, Aquabacterium sp. strain NJ1, capable of utilizing both liquid and solid alkanes, was deciphered. This is the first report of an Aquabacterium genome sequence. PMID:25477416

  7. A new isolation method for labyrinthulids using a bacterium, Psychrobacter phenylpyruvicus.

    PubMed

    Yokochi, T; Nakahara, T; Higashihara, T; Yamaoka, M; Kurane, R

    2001-01-01

    A new isolation method for labyrinthulids, marine microbes with spindle-shaped vegetative cells and gliding movement, is presented. The method for isolating labyrinthulids has been found to be more difficult and less reproducible than that for thraustochytrids, classified in the same order. So far serum seawater agar fortified with antibiotics has been proposed to be the best for isolation of labyrinthulids. The method presented here involves placing plant samples on an agar medium on which a marine bacterium, Psychrobacter phenylpyruvicus, has been grown. The new method, which utilizes fallen mangrove leaves as source material, was more than twice as effective as isolation agar medium without the bacterium. The increased effectiveness appears to derive partly from the bacterial colonies' delaying extension of fungal mycelium. The bacterium was more effective for the isolation of labyrinthulids than either the bacterium Shewanella sp. or the yeast Rhodotorula rubra. PMID:14961392

  8. IN SITU RT-PCR WITH A SULFATE-REDUCING BACTERIUM ISOLATED FROM SEAGRASS ROOTS

    EPA Science Inventory

    Bacteria considered to be obligate anaerobes internally colonize roots of the submerged macrophyte Halodule wrightii. A sulfate reducing bacterium, Summer lac 1, was isolated on lactate from H. wrightii roots. The isolate has physiological characteristics typical of Desulfovibri...

  9. Characterization of a Neochlamydia-like bacterium associated with epitheliocystis in cultured Arctic charr Salvelinus alpinus

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Infections of branchial epithelium by intracellular gram-negative bacteria, termed epitheliocystis, have limited culture of Arctic char (Salvelinus alpinus). To characterize a bacterium associated with epitheliocystis in cultured char, gills were sampled for histopathologic examination, conventiona...

  10. Extracellular electron transfer of a highly adhesive and metabolically versatile bacterium.

    PubMed

    Liu, Huan; Ishikawa, Masahito; Matsuda, Shoichi; Kimoto, Yuki; Hori, Katsutoshi; Hashimoto, Kazuhito; Nakanishi, Shuji

    2013-08-01

    Bacterial adhesion to a solid plays a predominant role in mediating the extracellular electron transfer for genus Acinetobactor, a metabolically versatile bacterium that can couple toluene degradation and electricity generation. PMID:23813865

  11. Enhancement of xylose utilization from corn stover by a recombinant bacterium for ethanol production

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Recombinant ethanologenic Escherichia coli ferments glucose, xylose and arabinose to ethanol. However, the bacterium preferentially utilizes glucose first, then arabinose and finally xylose (sequential utilization of sugars) during fermentation of lignocellulosic hydrolyzates to ethanol making the p...

  12. Draft Genome Sequence of Erythrobacter vulgaris Strain O1, a Glycosyl Hydrolase-Producing Bacterium

    PubMed Central

    Yaakop, Amira Suriaty; Chan, Chia Sing; Kahar, Ummirul Mukminin; Ee, Robson

    2015-01-01

    Erythrobacter vulgaris strain O1, a moderate halophile, was isolated from a beach in Johor, Malaysia. Here, we present the draft genome and suggest potential applications of this bacterium. PMID:25977433

  13. Characterization of a Neochlamydia-like Bacterium Associated with Epitheliocystis in Cultured Artic Char Salvelinus alpinus

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Infections of branchial epithelium by intracellular gram-negative bacteria, termed epitheliocystis, have limited culture of Arctic char (Salvelinus alpinus). To characterize a bacterium associated with epitheliocystis in cultured char, gills were sampled for histopathologic examination, conventional...

  14. Draft Genome Sequence of DLB, a Dyella-Like Bacterium from the Planthopper Hyalesthes obsoletus

    PubMed Central

    Lahav, Tamar; Zchori-Fein, Einat; Naor, Vered; Freilich, Shiri

    2016-01-01

    We report here the draft genome sequence of a Dyella-like bacterium (DLB) isolated from Hyalesthes obsoletus, the insect vector of the uncultivable mollicute bacterium “Candidatus Phytoplasma.” This isolate inhibits Spiroplasma melliferum, a cultivable mollicute. The draft genome of DLB consists of 4,196,214 bp, with a 68.6% G+C content, and 3,757 genes were predicted. PMID:27445378

  15. Complete genome of Martelella sp. AD-3, a moderately halophilic polycyclic aromatic hydrocarbons-degrading bacterium.

    PubMed

    Cui, Changzheng; Li, Zhijie; Qian, Jiangchao; Shi, Jie; Huang, Ling; Tang, Hongzhi; Chen, Xin; Lin, Kuangfei; Xu, Ping; Liu, Yongdi

    2016-05-10

    Martelella sp. strain AD-3, a moderate halophilic bacterium, was isolated from a petroleum-contaminated soil with high salinity in China. Here, we report the complete genome of strain AD-3, which contains one circular chromosome and two circular plasmids. An array of genes related to metabolism of polycyclic aromatic hydrocarbons and halophilic mechanism in this bacterium was identified by the whole genome analysis. PMID:26988395

  16. Endohyphal Bacterium Enhances Production of Indole-3-Acetic Acid by a Foliar Fungal Endophyte

    PubMed Central

    Hoffman, Michele T.; Gunatilaka, Malkanthi K.; Wijeratne, Kithsiri; Gunatilaka, Leslie; Arnold, A. Elizabeth

    2013-01-01

    Numerous plant pathogens, rhizosphere symbionts, and endophytic bacteria and yeasts produce the important phytohormone indole-3-acetic acid (IAA), often with profound effects on host plants. However, to date IAA production has not been documented among foliar endophytes -- the diverse guild of primarily filamentous Ascomycota that live within healthy, above-ground tissues of all plant species studied thus far. Recently bacteria that live within hyphae of endophytes (endohyphal bacteria) have been detected, but their effects have not been studied previously. Here we show not only that IAA is produced in vitro by a foliar endophyte (here identified as Pestalotiopsis aff. neglecta, Xylariales), but that IAA production is enhanced significantly when the endophyte hosts an endohyphal bacterium (here identified as Luteibacter sp., Xanthomonadales). Both the endophyte and the endophyte/bacterium complex appear to rely on an L-tryptophan dependent pathway for IAA synthesis. The bacterium can be isolated from the fungus when the symbiotic complex is cultivated at 36°C. In pure culture the bacterium does not produce IAA. Culture filtrate from the endophyte-bacterium complex significantly enhances growth of tomato in vitro relative to controls and to filtrate from the endophyte alone. Together these results speak to a facultative symbiosis between an endophyte and endohyphal bacterium that strongly influences IAA production, providing a new framework in which to explore endophyte-plant interactions. PMID:24086270

  17. Metabolomics evaluation of the impact of smokeless tobacco exposure on the oral bacterium Capnocytophaga sputigena.

    PubMed

    Sun, Jinchun; Jin, Jinshan; Beger, Richard D; Cerniglia, Carl E; Yang, Maocheng; Chen, Huizhong

    2016-10-01

    The association between exposure to smokeless tobacco products (STP) and oral diseases is partially due to the physiological and pathological changes in the composition of the oral microbiome and its metabolic profile. However, it is not clear how STPs affect the physiology and ecology of oral microbiota. A UPLC/QTof-MS-based metabolomics study was employed to analyze metabolic alterations in oral bacterium, Capnocytophaga sputigena as a result of smokeless tobacco exposure and to assess the capability of the bacterium to metabolize nicotine. Pathway analysis of the metabolome profiles indicated that smokeless tobacco extracts caused oxidative stress in the bacterium. The metabolomics data also showed that the arginine-nitric oxide pathway was perturbed by the smokeless tobacco treatment. Results also showed that LC/MS was useful in identifying STP constituents and additives, including caffeine and many flavoring compounds. No significant changes in levels of nicotine and its major metabolites were found when C. sputigena was cultured in a nutrient rich medium, although hydroxylnicotine and cotinine N-oxide were detected in the bacterial metabolites suggesting that nicotine metabolism might be present as a minor degradation pathway in the bacterium. Study results provide new insights regarding the physiological and toxicological effects of smokeless tobacco on oral bacterium C. sputigena and associated oral health as well as measuring the ability of the oral bacterium to metabolize nicotine. PMID:27480511

  18. Regulation of caffeate respiration in the acetogenic bacterium Acetobacterium woodii.

    PubMed

    Dilling, Sabrina; Imkamp, Frank; Schmidt, Silke; Müller, Volker

    2007-06-01

    The anaerobic acetogenic bacterium Acetobacterium woodii can conserve energy by oxidation of various substrates coupled to either carbonate or caffeate respiration. We used a cell suspension system to study the regulation and kinetics of induction of caffeate respiration. After addition of caffeate to suspensions of fructose-grown cells, there was a lag phase of about 90 min before caffeate reduction commenced. However, in the presence of tetracycline caffeate was not reduced, indicating that de novo protein synthesis is required for the ability to respire caffeate. Induction also took place in the presence of CO(2), and once a culture was induced, caffeate and CO(2) were used simultaneously as electron acceptors. Induction of caffeate reduction was also observed with H(2) plus CO(2) as the substrate, but the lag phase was much longer. Again, caffeate and CO(2) were used simultaneously as electron acceptors. In contrast, during oxidation of methyl groups derived from methanol or betaine, acetogenesis was the preferred energy-conserving pathway, and caffeate reduction started only after acetogenesis was completed. The differential flow of reductants was also observed with suspensions of resting cells in which caffeate reduction was induced prior to harvest of the cells. These cell suspensions utilized caffeate and CO(2) simultaneously with fructose or hydrogen as electron donors, but CO(2) was preferred over caffeate during methyl group oxidation. Caffeate-induced resting cells could reduce caffeate and also p-coumarate or ferulate with hydrogen as the electron donor. p-Coumarate or ferulate also served as an inducer for caffeate reduction. Interestingly, caffeate-induced cells reduced ferulate in the absence of an external reductant, indicating that caffeate also induces the enzymes required for oxidation of the methyl group of ferulate. PMID:17416687

  19. Jeongeupia chitinilytica sp. nov., a chitinolytic bacterium isolated from soil.

    PubMed

    Chen, Wen-Ming; Chang, Rey-Chang; Cheng, Chih-Yu; Shiau, Yu-Wen; Sheu, Shih-Yi

    2013-03-01

    A novel bacterium, designated strain Jchi(T), was isolated from soil in Taiwan and characterized using a polyphasic approach. Cells of strain Jchi(T) were aerobic, Gram-stain-negative, motile and rod-shaped. They contained poly-β-hydroxybutyrate granules and formed dark-yellow colonies. Growth occurred at 20-37 °C (optimum between 25 and 30 °C), at pH 6.0-8.0 (optimum between pH 7.0 and pH 8.0) and with 0-2 % NaCl (optimum between 0 and 1 %). Phylogenetic analyses based on 16S rRNA gene sequences indicated that strain Jchi(T) belonged to the genus Jeongeupia and that its closest neighbour was Jeongeupia naejangsanensis BIO-TAS4-2(T) (98.0 % sequence similarity). The major fatty acids (>10 %) of strain Jchi(T) were summed feature 3 (comprising C16 : 1ω7c and/or C16 : 1ω6c), C16 : 0 and C18 : 1ω7c. The major cellular hydroxy fatty acid was C12 : 0 3-OH. The isoprenoid quinone was Q-8 and the genomic DNA G+C content was 66.1 mol%. The polar lipid profile consisted of a mixture of phosphatidylethanolamine, phosphatidylglycerol, diphosphatidylglycerol, phosphatidylserine and two unidentified phospholipids. The DNA-DNA relatedness value between strain Jchi(T) and J. naejangsanensis BIO-TAS4-2(T) was about 41.0 %. On the basis of the genotypic and phenotypic data, strain Jchi(T) represents a novel species in the genus Jeongeupia, for which the name Jeongeupia chitinilytica sp. nov. is proposed. The type strain is Jchi(T) ( = BCRC 80367(T)  = KCTC 23701(T)). PMID:22659500

  20. Characterization of a rhodanese from the cyanogenic bacterium Pseudomonas aeruginosa.

    PubMed

    Cipollone, Rita; Bigotti, Maria Giulia; Frangipani, Emanuela; Ascenzi, Paolo; Visca, Paolo

    2004-12-01

    Pseudomonas aeruginosa, the rRNA group I type species of genus Pseudomonas, is a Gram-negative, aerobic bacterium responsible for serious infection in humans. P. aeruginosa pathogenicity has been associated with the production of several virulence factors, including cyanide. Here, the biochemical characterization of recombinant P. aeruginosa rhodanese (Pa RhdA), catalyzing the sulfur transfer from thiosulfate to a thiophilic acceptor, e.g., cyanide, is reported. Sequence homology analysis of Pa RhdA predicts the sulfur-transfer reaction to occur through persulfuration of the conserved catalytic Cys230 residue. Accordingly, the titration of active Pa RhdA with cyanide indicates the presence of one extra sulfur bound to the Cys230 Sgamma atom per active enzyme molecule. Values of K(m) for thiosulfate binding to Pa RhdA are 1.0 and 7.4mM at pH 7.3 and 8.6, respectively, and 25 degrees C. However, the value of K(m) for cyanide binding to Pa RhdA (=14 mM, at 25 degrees C) and the value of V(max) (=750 micromol min(-1)mg(-1), at 25 degrees C) for the Pa RhdA-catalyzed sulfur-transfer reaction are essentially pH- and substrate-independent. Therefore, the thiosulfate-dependent Pa RhdA persulfuration is favored at pH 7.3 (i.e., the cytosolic pH of the bacterial cell) rather than pH 8.6 (i.e., the standard pH for rhodanese activity assay). Within this pH range, conformational change(s) occur at the Pa RhdA active site during the catalytic cycle. As a whole, rhodanese may participate in multiple detoxification mechanisms protecting P. aeruginosa from endogenous and environmental cyanide. PMID:15522204

  1. Metabolic Evolution of a Deep-Branching Hyperthermophilic Chemoautotrophic Bacterium

    PubMed Central

    Braakman, Rogier; Smith, Eric

    2014-01-01

    Aquifex aeolicus is a deep-branching hyperthermophilic chemoautotrophic bacterium restricted to hydrothermal vents and hot springs. These characteristics make it an excellent model system for studying the early evolution of metabolism. Here we present the whole-genome metabolic network of this organism and examine in detail the driving forces that have shaped it. We make extensive use of phylometabolic analysis, a method we recently introduced that generates trees of metabolic phenotypes by integrating phylogenetic and metabolic constraints. We reconstruct the evolution of a range of metabolic sub-systems, including the reductive citric acid (rTCA) cycle, as well as the biosynthesis and functional roles of several amino acids and cofactors. We show that A. aeolicus uses the reconstructed ancestral pathways within many of these sub-systems, and highlight how the evolutionary interconnections between sub-systems facilitated several key innovations. Our analyses further highlight three general classes of driving forces in metabolic evolution. One is the duplication and divergence of genes for enzymes as these progress from lower to higher substrate specificity, improving the kinetics of certain sub-systems. A second is the kinetic optimization of established pathways through fusion of enzymes, or their organization into larger complexes. The third is the minimization of the ATP unit cost to synthesize biomass, improving thermodynamic efficiency. Quantifying the distribution of these classes of innovations across metabolic sub-systems and across the tree of life will allow us to assess how a tradeoff between maximizing growth rate and growth efficiency has shaped the long-term metabolic evolution of the biosphere. PMID:24516572

  2. Paenibacillus xylanilyticus sp. nov., an airborne xylanolytic bacterium.

    PubMed

    Rivas, Raúl; Mateos, Pedro F; Martínez-Molina, Eustoquio; Velázquez, Encarna

    2005-01-01

    During a search for xylan-degrading micro-organisms, a sporulating bacterium was recovered from xylan-containing agar plates exposed to air in a research laboratory (Salamanca University, Spain). The airborne isolate (designated strain XIL14T) was identified by 16S rRNA gene sequencing as representing a Paenibacillus species most closely related to Paenibacillus illinoisensis JCM 9907T (99.3 % sequence similarity) and Paenibacillus pabuli DSM 3036T (98 % sequence similarity). Phenotypic, chemotaxonomic and DNA-DNA hybridization data indicated that the isolate belongs to a novel species of the genus Paenibacillus. Cells of strain XIL14T were motile, sporulating, rod-shaped, Gram-positive and facultatively anaerobic. The predominant cellular fatty acids were anteiso-C(15 : 0) and C(16 : 0). The DNA G+C content of strain XIL14T was 50.5 mol%. Growth was observed with many carbohydrates, including xylan, as the only carbon source and gas production was not observed from glucose. Catalase was positive and oxidase was negative. The airborne isolate produced a variety of hydrolytic enzymes, including xylanases, amylases, gelatinase and beta-galactosidase. DNA-DNA hybridization levels between strain XIL14T and P. illinoisensis DSM 11733T and P. pabuli DSM 3036T were 43.3 and 36.3 %, respectively. According to the data obtained, strain XIL14T is considered to represent a novel species for which the name Paenibacillus xylanilyticus sp. nov. is proposed (=LMG 21957T=CECT 5839T). PMID:15653909

  3. Metabolic evolution of a deep-branching hyperthermophilic chemoautotrophic bacterium.

    PubMed

    Braakman, Rogier; Smith, Eric

    2014-01-01

    Aquifex aeolicus is a deep-branching hyperthermophilic chemoautotrophic bacterium restricted to hydrothermal vents and hot springs. These characteristics make it an excellent model system for studying the early evolution of metabolism. Here we present the whole-genome metabolic network of this organism and examine in detail the driving forces that have shaped it. We make extensive use of phylometabolic analysis, a method we recently introduced that generates trees of metabolic phenotypes by integrating phylogenetic and metabolic constraints. We reconstruct the evolution of a range of metabolic sub-systems, including the reductive citric acid (rTCA) cycle, as well as the biosynthesis and functional roles of several amino acids and cofactors. We show that A. aeolicus uses the reconstructed ancestral pathways within many of these sub-systems, and highlight how the evolutionary interconnections between sub-systems facilitated several key innovations. Our analyses further highlight three general classes of driving forces in metabolic evolution. One is the duplication and divergence of genes for enzymes as these progress from lower to higher substrate specificity, improving the kinetics of certain sub-systems. A second is the kinetic optimization of established pathways through fusion of enzymes, or their organization into larger complexes. The third is the minimization of the ATP unit cost to synthesize biomass, improving thermodynamic efficiency. Quantifying the distribution of these classes of innovations across metabolic sub-systems and across the tree of life will allow us to assess how a tradeoff between maximizing growth rate and growth efficiency has shaped the long-term metabolic evolution of the biosphere. PMID:24516572

  4. Interaction of Cadmium With the Aerobic Bacterium Pseudomonas Mendocina

    NASA Astrophysics Data System (ADS)

    Schramm, P. J.; Haack, E. A.; Maurice, P. A.

    2006-05-01

    The fate of toxic metals in the environment can be heavily influenced by interaction with bacteria in the vadose zone. This research focuses on the interactions of cadmium with the strict aerobe Pseudomonas mendocina. P. mendocina is a gram-negative bacterium that has shown potential in the bioremediation of recalcitrant organic compounds. Cadmium is a common environmental contaminant of wide-spread ecological consequence. In batch experiments P. mendocina shows typical bacterial growth curves, with an initial lag phase followed by an exponential phase and a stationary to death phase; concomitant with growth was an increase in pH from initial values of 7 to final values at 96 hours of 8.8. Cd both delays the onset of the exponential phase and decreases the maximum population size, as quantified by optical density and microscopic cell counts (DAPI). The total amount of Cd removed from solution increases over time, as does the amount of Cd removed from solution normalized per bacterial cell. Images obtained with transmission electron microscopy (TEM) showed the production of a cadmium, phosphorus, and iron containing precipitate that was similar in form and composition to precipitates formed abiotically at elevated pH. However, by late stationary phase, the precipitate had been re-dissolved, perhaps by biotic processes in order to obtain Fe. Stressed conditions are suggested by TEM images showing the formation of pili, or nanowires, when 20ppm Cd was present and a marked decrease in exopolysaccharide and biofilm material in comparison to control cells (no cadmium added).

  5. Bacterium-Mimicking Nanoparticle Surface Functionalization with Targeting Motifs

    PubMed Central

    Lai, Mei-Hsiu; Clay, Nicholas E.; Kim, Dong Hyun; Kong, Hyunjoon

    2015-01-01

    In recent years, surface modification of nanocarriers with targeting motifs has been explored to modulate delivery of various diagnostic, sensing and therapeutic molecular cargos to desired sites of interest in in vitro bioengineering platforms and in vivo pathologic tissue. However, most surface functionalization approaches are often plagued by complex chemical modifications and effortful purifications. To resolve such challenges, this study demonstrates a unique method to immobilize antibodies that can act as targeting motifs on the surfaces of nanocarriers, inspired by a process that bacteria use for immobilization of the host’s antibodies. We hypothesized that alkylated Staphylococcus aureus protein A (SpA) would self-assemble with micelles and subsequently induce stable coupling of antibodies to the micelles. We examined this hypothesis by using poly(2-hydroxyethyl-co-octadecyl aspartamide) (PHEA-g-C18) as a model polymer to form micelles. The self-assembly between micelles and alkylated SpA became more thermodynamically favorable by increasing the degree of substitution of octadecyl chains to PHEA-g-C18, due to a positive entropy change. Lastly, the simple mixing of SpA-PA-coupled micelles with antibodies resulted in the micelles coated by antibodies, as confirmed with a fluorescence resonance energy transfer (FRET) assay. The micelles coated by antibodies to VCAM-1 or integrin αv displayed higher binding affinity to a substrate coated by VCAM-1 and integrin αvβ3, respectively, than other controls, as evaluated with surface plasmon resonance (SPR) spectroscopy and a circulation-simulating flow chamber. We envisage this bacterium-inspired protein immobilization approach will be useful to improving the quality of targeted delivery of nanoparticles, and can be extended to modify the surface of a wide array of nanocarriers. PMID:25804130

  6. Carbonate biomineralization induced by soil bacterium Bacillus megaterium

    NASA Astrophysics Data System (ADS)

    Lian, Bin; Hu, Qiaona; Chen, Jun; Ji, Junfeng; Teng, H. Henry

    2006-11-01

    Biogenic carbonates spawned from microbial activities are common occurrences in soils. Here, we investigate the carbonate biomineralization mediated by the bacterium Bacillus megaterium, a dominant strain separated from a loess profile in China. Upon completing bacterial cultivation, the ensuring products are centrifuged, and the resultant supernatant and the concentrated bacterial sludge as well as the un-separated culture are added separately into a Ca-CO 3 containing solution for crystallization experiments. Results of XRD and SEM analysis indicate that calcite is the dominant mineral phase formed when the bacteria are present. When the supernatant alone is used, however, a significant portion of vaterite is also precipitated. Experimental results further reveal that the bacteria have a strong tendency to colonize the center area of the calcite {1 0 1¯ 4} faces. Observed crystal morphology suggests that the bacterial colony may promote the growth normal to each individual {1 0 1¯ 4} face of calcite when the cell concentration is high, but may retard it or even cause dissolution of the immediate substrate surfaces when the concentration is low. SEM images taken at earlier stages of the crystallization experiments demonstrate the nucleation of calcite on the bacterial cell walls but do not show obvious morphological changes on the nanometer- to submicron-sized nuclei. δ 13C measurements unveil that the crystals grown in the presence of bacteria are further enriched in the heavy carbon isotope, implying that the bacterial metabolism may not be the carbon sources for the mineralization. Based upon these findings, we propose a mechanism for the B. megaterium mediated calcite mineralization and conclude that the whole process involves epi- and inter-cellular growth in the local microenvironments whose conditions may be controlled by cell sequestration and proton pumping during bacterial respiration.

  7. Competitive PCR for Quantitation of a Cytophaga-Flexibacter-Bacteroides Phylum Bacterium Associated with the Tuber borchii Vittad. Mycelium

    PubMed Central

    Barbieri, Elena; Riccioni, Giulia; Pisano, Anna; Sisti, Davide; Zeppa, Sabrina; Agostini, Deborah; Stocchi, Vilberto

    2002-01-01

    An uncultured bacterium associated with the ectomycorrhizal fungus Tuber borchii Vittad. was identified as a novel member of the Cytophaga-Flexibacter-Bacteroides group. Utilizing a quantitative PCR targeting the 16S rRNA gene, we relatively quantified this bacterium in the host. The estimated number of bacteria was found to be approximately 106 cells per 30-day-old T. borchii mycelium culture. This represents the first molecular attempt to enumerate an uncultured bacterium associated with a mycorrhizal fungus. PMID:12450871

  8. Regulation of Polyhydroxybutyrate Synthesis in the Soil Bacterium Bradyrhizobium diazoefficiens.

    PubMed

    Quelas, J I; Mesa, S; Mongiardini, E J; Jendrossek, D; Lodeiro, A R

    2016-07-15

    Polyhydroxybutyrate (PHB) is a carbon and energy reserve polymer in various prokaryotic species. We determined that, when grown with mannitol as the sole carbon source, Bradyrhizobium diazoefficiens produces a homopolymer composed only of 3-hydroxybutyrate units (PHB). Conditions of oxygen limitation (such as microoxia, oxic stationary phase, and bacteroids inside legume nodules) were permissive for the synthesis of PHB, which was observed as cytoplasmic granules. To study the regulation of PHB synthesis, we generated mutations in the regulator gene phaR and the phasin genes phaP1 and phaP4 Under permissive conditions, mutation of phaR impaired PHB accumulation, and a phaP1 phaP4 double mutant produced more PHB than the wild type, which was accumulated in a single, large cytoplasmic granule. Moreover, PhaR negatively regulated the expression of phaP1 and phaP4 as well as the expression of phaA1 and phaA2 (encoding a 3-ketoacyl coenzyme A [CoA] thiolases), phaC1 and phaC2 (encoding PHB synthases), and fixK2 (encoding a cyclic AMP receptor protein [CRP]/fumarate and nitrate reductase regulator [FNR]-type transcription factor of genes for microoxic lifestyle). In addition to the depressed PHB cycling, phaR mutants accumulated more extracellular polysaccharides and promoted higher plant shoot dry weight and competitiveness for nodulation than the wild type, in contrast to the phaC1 mutant strain, which is defective in PHB synthesis. These results suggest that phaR not only regulates PHB granule formation by controlling the expression of phasins and biosynthetic enzymes but also acts as a global regulator of excess carbon allocation and symbiosis by controlling fixK2 IMPORTANCE: In this work, we investigated the regulation of polyhydroxybutyrate synthesis in the soybean-nodulating bacterium Bradyrhizobium diazoefficiens and its influence in bacterial free-living and symbiotic lifestyles. We uncovered a new interplay between the synthesis of this carbon reserve polymer

  9. Photoactive yellow protein from the halophilic bacterium Salinibacter ruber.

    PubMed

    Memmi, Samy; Kyndt, John; Meyer, Terry; Devreese, Bart; Cusanovich, Michael; Van Beeumen, Jozef

    2008-02-19

    A gene for photoactive yellow protein (PYP) was identified from the genome sequence of the extremely halophilic aerobic bacterium Salinibacter ruber (Sr). The sequence is distantly related to the prototypic PYP from Halorhodospira halophila (Hh) (37% identity) and contains most of the amino acid residues identified as necessary for function. However, the Sr pyp gene is not flanked by its two biosynthetic genes as in other species. To determine as to whether the Sr pyp gene encodes a functional protein, we cloned and expressed it in Escherichia coli, along with the genes for chromophore biosynthesis from Rhodobacter capsulatus. The Sr PYP has a 31-residue N-terminal extension as compared to other PYPs that appears to be important for dimerization; however, truncation of these extra residues did not change the spectral and photokinetic properties. Sr PYP has an absorption maximum at 431 nm, which is at shorter wavelengths than the prototypical Hh PYP (at 446 nm). It is also photoactive, being reversibly bleached by either blue or white light. The kinetics of dark recovery is slower than any of the PYPs reported to date (4.27 x 10(-4) s(-1) at pH 7.5). Sr PYP appears to have a normal photocycle with the I1 and I2 intermediates. The presence of the I2' intermediate is also inferred on the basis of the effects of temperature and alchohol on recovery. Sr PYP has an intermediate spectral form in equilibrium with the 431 nm form, similar to R. capsulatus PYP and the Y42F mutant of Hh PYP. Increasing ionic strength stabilizes the 431 nm form at the expense of the intermediate spectral form, and the kinetics of recovery is accelerated 6.4-fold between 0 and 3.5 M salt. This is observed with ions from both the chaotropic and the kosmotropic series. Ionic strength also stabilizes PYP against thermal denaturation, as the melting temperature is increased from 74 degrees C in buffer alone to 92 degrees C in 2 M KCl. Sr accumulates KCl in the cytoplasm, like Halobacterium, to

  10. Further studies on a human intestinal bacterium Ruminococcus sp. END-1 for transformation of plant lignans to mammalian lignans.

    PubMed

    Jin, Jong-Sik; Hattori, Masao

    2009-08-26

    A human intestinal bacterium Ruminococcus (R.) sp. END-1 capable of oxidizing (-)-enterodiol to (-)-enterolactone, enantioselectively, was further investigated from the perspective of transformation of plant lignans to mammalian lignans; A cell-free extract of the bacterium transformed (-)-enterodiol to (-)-enterolactone through an intermediate, enterolactol. The bacterium showed not only oxidation but also demethylation and deglucosylation activities for plant lignans. Arctiin and secoisolariciresinol diglucoside were converted to (-)-dihydroxyenterolactone and (+)-dihydroxyenterodiol, respectively. Moreover, by coincubation with Eggerthella sp. SDG-2, the bacterium transformed arctiin and secoisolariciresinol diglucoside to (-)-enterolactone and (+)-enterodiol, respectively. PMID:19630415