Production of syngenetic minerals with struvite by myxococcus coralloides D

The formation under laboratory conditions of newberyite, schertelite, and taylorite in conjunction with struvite by the bacterium Myxococcus coralloides D is reported for the first time. The presence of these syngenetic minerals with struvite was only detected in static liquid cultures.     

Polyphosphate glucokinase and ATP glucokinase activities in Mycococcus coralloides D

Polyphosphate glucokinase and ATP glucokinase were detected in cell-free extracts of Myxococcus coralloides strain D, but pyrophosphate glucokinase was not detected. Both glucokinase activities were separated by chromatography. The approximate molecular weight is 61 000 for polyphosphate glucokinase and 47 000 for ATP glucokinase. Substrate specificity and pH optimum was studied in the polyphosphate glucokinase. Polyphosphate and ATP glucokinase activities were verified by ¹³C Nuclear Magnetic Resonance.     

Effect of phosphate on antibiotic and extracellular protein production by Myxococcus coralloides D

Summary The effect of inorganic phosphate concentrations on antibiotic and extracellular protein production by Myxococcus coralloides D have been examined. Antibiotic production by growing cells of this myxobacterium was maximal at phosphate concentrations of 10–20 mM, but was inhibited by concentrations higher than 20 mM. The total extracellular protein and the extracellular protein per cell ratio were independent of phosphate levels in the culture broth. Offprint requests to: J. M. Arias     

Effects of pH and phosphate on the production of struvite by Myxococcus xanthus

We studied the influence of pH and the phosphate content of the culture medium on the precipitation of struvite by Myxococcus xanthus, a bacterium that undergoes autolysis at the end of its exponential growth phase in liquid cultures. The best results were obtained with pH values between 7.2 and 8.0 and with a phosphate concentration of 10 mM. Our studies reveal for the first time that the precipitation of struvite always begins at the onset of autolysis and that culture conditions favoring the early occurrence of autolysis also enhance struvite production.     

Silver Sorption to Myxococcus xanthus Biomass

This paper deals with silver sorption to Myxococcus xanthus biomass. The dry biomass of this microorganism is shown to be a good sorbent for the recovery of silver present at low solution concentrations. Between initial silver concentrations of 2 and 0.05 mM, the percentage of accumulation ranges from 8.12% to 75% of the total silver present in the solution. Transmission electron microscopy study of M. xanthus wet biomass after silver accumulation shows the sorption within the extracellular polysaccharide, on the cell wall, and in the cytoplasm. The presence of silver deposits in the cytoplasm indicates that at least two mechanisms are involved in silver sorption by this bacterium biomass. First, silver was bound to the cell surface and extracellular polysaccharide, and second, a silver intracellular deposition process took place. The higher amount of silver deposits in the extracellular polysaccharide, present abundantly in M. xanthus cells, explains the capacity of this bacterium to bind silver efficiently. The results obtained indicate that the removal of silver by M. xanthus from the diluted solutions could be used in recycling this valuable metal. One interesting observation of this investigation is the crystalline form, possibly as chlorargyrite, in which the silver deposits are found in the M. xanthus cells.     

Bacteriocins from Myxococcus fulvus (Myxobacterales)

Bacteriocin-like activities were found in several Myxococcus fulvus strains. One strain, Mxf16, exerted strong inhibitory effects on several myxobacterial strains. Synthesis of its bacteriocinic activity could not be induced by mitomycin. Electrophoresis and molecular sieve chromatography revealed at least three different bacteriocinic substances of low molecular weight.List of Abbreviations cas lm Casitone liquid medium - TCA trichloroacetic acid     

Phenotypic analyses of frz and dif double mutants of Myxococcus xanthus

Myxococcus xanthus is a Gram-negative gliding bacterium that aggregates and develops into multicellular fruiting bodies in response to starvation. Two chemosensory systems (frz and dif), both of which are homologous to known chemotaxis proteins, were previously identified through characterization of various developmental mutants. This study aims to examine the interaction between these two systems since both of them are required for fruiting body formation of M. xanthus. Through detailed phenotypic analyses of frz and dif double mutants, we found that both frz and dif are involved in cellular reversal and social motility; however, the frz genes are epistatic in controlling cellular reversal, whereas the dif genes are epistatic in controlling social motility. The study suggests that the integration of these two chemotaxis systems may play a central role in controlling the complicated social behaviors of M. xanthus.     

Cell‐fate determination in Myxococcus xanthus development: Network dynamics and novel predictions

Myxococcus xanthus is a myxobacterium that exhibits aggregation and cellular differentiation during the formation of fruiting bodies. Therefore, it has become a valuable model system to study the transition to multicellularity via cell aggregation. Although there is a vast set of experimental information for the development on M. xanthus, the dynamics behind cell‐fate determination in this organism's development remain unclear. We integrate the currently available evidence in a mathematical network model that allows to test the set of molecular elements and regulatory interactions that are sufficient to account for the specification of the cell types that are observed in fruiting body formation. Besides providing a dynamic mechanism for cell‐fate determination in the transition to multicellular aggregates of M. xanthus, this model enables the postulation of specific mechanisms behind some experimental observations for which no explanations have been provided, as well as new regulatory interactions that can be experimentally tested. Finally, this model constitutes a formal basis on which the continuously emerging data for this system can be integrated and interpreted.     

Identification and Characterization of the Myxococcus xanthus argE Gene

The chromosomal acetylornithine deacetylase (argE) gene of Myxococcus xanthus was identified via homology to acetylornithine deacetylases from other bacterial species. A mutant carrying a disruption in argE was unable to grow on minimal media lacking supplemental arginine and formed fruiting bodies and spores in response to arginine starvation at high cell density.     

Isolation and characterization of new bacteriophages for Myxococcus xanthus

Bacteriophages for Myxococcus xanthus of similar morphology to phage Mx4 were isolated from cultures of a variety of myxobacterial species. Phages similar to Mx1 and Mx8 were obtained by infecting M. xanthus with one of the phages of the Mx4 group that had been treated with either UV light or a chemical mutagen.The DNA molecules from the phages were characterized by electron microscopy. One phage, Mx113, contains an unusual type of terminal redundancy revealed by examination of denatured and re-annealed DNA.Several of the phages of the Mx4 group and the other two new phages, Mx113 and Mx811, were found capable of transducing genetic markers in M. xanthus.One phage, Mx416, was characterized in more detail. It establishes true lysogens in M. xanthus; the phage plaques on both a non-motile mutant and also on a wild-type host although it is restricted in the latter.We dedicate this paper to Professor Dr. Hans Kühlwein in the year of his retirement and in recognition of his many contributions to the study of Myxobacteria     

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

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.     

The extracellular proteases of Myxococcus xanthus

Abstract A zymogram technique was used to resolve the proteases from the culture supernatants of three strains derived from Myxococcus xanthus FB. Of the 8 bands obtained, 3 were possibly proteolytic artefacts, and another may be derived from membrane vesicles or fragments. 3 of the bands were tentatively identified as serine proteases by affinity labelling. A non-motile, non-fruiting strain, M. xanthus DZ1, differed from 2 wild-type strains, NCIB9412 and DK101, in the relative intensity of certain bands, and all 3 strains differed qualitatively from M. xanthus XK, which is not FB-derived.     

An unusual pattern of carbohydrate utilization in Corallococcus (Myxococcus) coralloides (Myxobacterales)

The myxobacterium, Corallococcus (Myxococcus) coralloides strain Cc c127, could not utilize mono- and disaccharides, but maltotriose and the polysaccharides starch, amylose, amylopectin, and pullulan stimulated growth. Radioactive CO₂ was set free from ¹⁴C-labeled starch. When starch was degraded, small amounts of maltose and glucose accumulated in the culture supernatant. Maltotriose, however, appeared only temporarily. Outside the cells, the trisaccharide could not be split into glucose and maltose. Pullulan was hydrolyzed exclusively into a trisaccharide which during growth was immediately consumed. Hexokinase, glucose-6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase and phosphoglucomutase could readily be demonstrated in cell extracts, but fructose-1,6-diphosphate aldolase was present with low activity only. The data suggest that intracellular glucose is metabolized mainly via the pentose phosphate pathway.Prof. Dr. Gerhard Drews gratefully dedicated to his 60th birthday     

Mutants of Myxococcus xanthus insensitive to glycerol-induced myxospore formation

Mutants of Myxococcus xanthus FB_t unable to form myxospores in response to 0.5 M glycerol arise spontaneously with a frequency of 1–3×10^–5. These mutants are designated glc. Ultraviolet mutagenesis increases the frequency to a maximum of 7% of the survivors. The reversion frequency following ultraviolet irradiation of spontaneous glc mutants is less than 10^–3. Of four glc mutants examined, none form myxospores in response to the alternative inducers, ethylene glycol and dimethyl sulphoxide. One glc mutant is induced by 1.5 M glycerol; strain FB_t responds to this glycerol concentration with low efficiency myxospore formation. Strain FB_t and glc mutants all produce myxospores with low efficiency in response to phenyl ethanol. Of 117 glc mutants tested, 109 form fruiting bodies containing mature myxospores; thus, mutations to the glc phenotype do not normally block myxospore formation within the fruiting cycle of the organism.     

橙色粘球菌子实体形成过程的显微观察

利用体式显微镜(stereomicroscope,SMC)和扫描电镜(scanning electron microscope,SEM)对橙色粘球菌(Myxococcus fulvus)的子实体形成过程进行为期8 d的生长周期观察,揭示橙色粘球菌由营养体逐渐聚集变成子实体的过程;SMC观察得到粘细菌菌落形成聚集以及颜色逐渐变深,并最后形成突起的鲜亮的橙色球状子实体。SEM观察得到明显的群体细胞定向运动以及细胞堆积,粘细菌细胞由杆状营养体向球状粘孢子变化,并最终形成由粘孢子组成的球状子实体。     

Fatty Acids of Myxococcus xanthus

Fatty acids were extracted from saponified vegetative cells and myxospores of Myxococcus xanthus and examined as the methyl esters by gas-liquid chromatography. The acids consisted mainly of C₁₄ to C₁₇ species. Branched acids predominated, and iso-pentadecanoic acid constituted half or more of the mixture. The other leading component (11–28%) was found to be 11-n-hexadecenoic acid. Among the unsaturated acids were two diunsaturated ones, an n-hexadecadienoic acid and an iso-heptadecadienoic acid. No significant differences between the fatty acid compositions of the vegetative cells and myxospores could be detected. The fatty acid composition of M. xanthus was found to be markedly similar to that of Stigmatella aurantiaca. It is suggested that a fatty acid pattern consisting of a large proportion of iso-branched C₁₅ and C₁₇ acids and a substantial amount of an n-16:1 acid is characteristic of myxobacteria.     

1H, 13C and 15N backbone and side chain resonance assignments of the C-terminal domain of CdnL from Myxococcus xanthus

CdnL, a 164-residue protein essential for Myxococcus xanthus viability, is a member of a large family of bacterial proteins of unknown structure and function. Here, we report the ¹H, ¹³C and ¹⁵N backbone and side chain assignments for the stable C-terminal domain of CdnL identified by limited proteolysis.     

SigF, a new sigma factor required for a motility system of Myxococcus xanthus

A new sigma factor, SigF, was identified from the social and developmental bacterium Myxococcus xanthus. SigF is required for fruiting body formation during development as well as social motility during vegetative growth. Analysis of gene expression indicates that it is possible that the sigF gene is involved in regulation of an unidentified gene for social motility.     

Transposon Tn5 confers streptomycin resistance to Myxococcus xanthus

Abstract In addition to resistance to kanamycin, transposon Tn 5 confers resistance to streptomycin in Myxococcus xanthus . The streptomycin determinant is located within the Bgl II fragment of Tn 5 . The level of resistance varies among strains bearing Tn 5 insertions in different chromosomal loci and there is a correlation between the levels of resistance to streptomycin and to kanamycin.     

A comprehensive insight into the lipid composition of Myxococcus xanthus by UPLC-ESI-MS

Analysis of whole cell lipid extracts of bacteria by means of ultra-performance (UP)LC-MS allows a comprehensive determination of the lipid molecular species present in the respective organism. The data allow conclusions on its metabolic potential as well as the creation of lipid profiles, which visualize the organism’s response to changes in internal and external conditions. Herein, we describe: i) a fast reversed phase UPLC-ESI-MS method suitable for detection and determination of individual lipids from whole cell lipid extracts of all polarities ranging from monoacylglycerophosphoethanolamines to TGs; ii) the first overview of a wide range of lipid molecular species in vegetative Myxococcus xanthus DK1622 cells; iii) changes in their relative composition in selected mutants impaired in the biosynthesis of α-hydroxylated FAs, sphingolipids, and ether lipids; and iv) the first report of ceramide phosphoinositols in M. xanthus, a lipid species previously found only in eukaryotes.