Myxobacteria are Gram-negative eubacteria and they thrive in a variety of habitats including soil rich in organic matter, rotting wood, animal dung and marine environment. Myxobacteria are a ...promising source of new compounds associated with diverse bioactive spectrum and unique mode of action. The genome information of myxobacteria has revealed many orphan biosynthetic pathways indicating that these bacteria can be the source of several novel natural products. In this review, we highlight the biology of myxobacteria with emphasis on their habitat, life cycle, isolation methods and enlist all the bioactive secondary metabolites purified till date and their mode of action.
Sterol Synthesis in Diverse Bacteria Wei, Jeremy H; Yin, Xinchi; Welander, Paula V
Frontiers in microbiology,
06/2016, Letnik:
7
Journal Article
Recenzirano
Odprti dostop
Sterols are essential components of eukaryotic cells whose biosynthesis and function has been studied extensively. Sterols are also recognized as the diagenetic precursors of steranes preserved in ...sedimentary rocks where they can function as geological proxies for eukaryotic organisms and/or aerobic metabolisms and environments. However, production of these lipids is not restricted to the eukaryotic domain as a few bacterial species also synthesize sterols. Phylogenomic studies have identified genes encoding homologs of sterol biosynthesis proteins in the genomes of several additional species, indicating that sterol production may be more widespread in the bacterial domain than previously thought. Although the occurrence of sterol synthesis genes in a genome indicates the potential for sterol production, it provides neither conclusive evidence of sterol synthesis nor information about the composition and abundance of basic and modified sterols that are actually being produced. Here, we coupled bioinformatics with lipid analyses to investigate the scope of bacterial sterol production. We identified oxidosqualene cyclase (Osc), which catalyzes the initial cyclization of oxidosqualene to the basic sterol structure, in 34 bacterial genomes from five phyla (Bacteroidetes, Cyanobacteria, Planctomycetes, Proteobacteria, and Verrucomicrobia) and in 176 metagenomes. Our data indicate that bacterial sterol synthesis likely occurs in diverse organisms and environments and also provides evidence that there are as yet uncultured groups of bacterial sterol producers. Phylogenetic analysis of bacterial and eukaryotic Osc sequences confirmed a complex evolutionary history of sterol synthesis in this domain. Finally, we characterized the lipids produced by Osc-containing bacteria and found that we could generally predict the ability to synthesize sterols. However, predicting the final modified sterol based on our current knowledge of sterol synthesis was difficult. Some bacteria produced demethylated and saturated sterol products even though they lacked homologs of the eukaryotic proteins required for these modifications emphasizing that several aspects of bacterial sterol synthesis are still completely unknown.
Using MCF7 breast cancer cells, we tested the anticancer activity of metabolites from 130 strains of myxobacteria newly isolated in South Korea. Of these, three strains whose metabolites had high ...anticancer activity and low cell toxicity were selected and identified by their fruiting body morphology, cell morphology, and 16S rRNA sequence. Strains KYC4030 and KYC4048 were determined to be Myxococcus fulvus, whereas strain KYC4081 was identified as Corallococcus coralloides. We found that metabolites of M. fulvus KYC4048 demonstrated no toxicity in normal cells but specifically induced cancer cell death by suppressing the expression of WNT2B. This discovery highlights the value of assessing the metabolic and biomedical potential of myxobacteria, even those that are already known but were isolated from new areas, and the possible use of metabolites from M. fulvus KYC4048 in cancer treatment.
Myxobacteria are natural predators of microorganisms and the subjects of concerted efforts to identify novel antimicrobial compounds. Myxobacterial predatory activity seems to require more than just ...the possession of specific antimicrobial metabolites. Thus a holistic approach to studying predation promises novel insights into antimicrobial action. Here, we report the isolation of 113 myxobacteria from samples of soil taken from a range of habitats in mid Wales. Predatory activity of each isolate was quantified against a panel of clinically important prey organisms, including
, and three species of
. Myxobacterial isolates exhibited a wide range of predation activity profiles against the panel of prey. Efficient predation of all prey by isolates within the collection was observed, with
and
proving particularly susceptible to myxobacterial predation. Notably efficient predators tended to be proficient at predating multiple prey organisms, suggesting they possess gene(s) encoding a broad range killing activity. However, predatory activity was not congruent with phylogeny, suggesting prey range is subject to relatively rapid specialization, potentially involving lateral gene transfer. The broad but patchy prey ranges observed for natural myxobacterial isolates also implies multiple (potentially overlapping) genetic determinants are responsible for dictating predatory activity.
Myxobacteria are Gram negative bacteria commonly found in soil, tree bark, and decay wood. These bacteria have unique social behaviors by forming fruiting bodies, moving by gliding motility and ...preying on other microorganisms. The research was conducted to isolate, characterize, and identify indigenous myxobacteria from Sumba and Papua Islands of Indonesia as a preliminary step to utilize their potential in the pharmaceutical industry. Myxobacteria were isolated using filter paper and baiting with Escherichia coli to obtain cellulolytic and bacteriolytic myxobacteria, respectively. Characterization of myxobacteria was performed with Gram staining, observation on pigmentation, morphology of vegetative cells, fruiting bodies, and myxospores. Molecular identification was conducted based on 16S rRNA gene sequence analysis. A total of 10 myxobacterial strains were successfully isolated and purified. All isolates obtained were Gram negative, rod shaped with yellow or orange pigmentation. Fruiting bodies observed contained spherical myxospores. Molecular identification of these bacterial strains showed that they belong to myxobacteria from suborder Cystobacterineae, namely Myxococcus fulvus, Myxococcus stipitatus, and Melittangium lichenicola. To our knowledge, this is the first record of their occurrence in Indonesia.
Extracellular enzymes play important roles in myxobacteria degrading macromolecules and preying on other microorganisms. Glycoside hydrolases 19 (GH19) are widely present in myxobacteria, but their ...evolution and biological functions have not been fully elucidated. Here we investigated the comparative secretory proteome of
c25j21 in the presence of cellulose and chitin. A total of 313 proteins were detected, including 16 carbohydrate-active enzymes (CAZymes), 7 of which were induced by cellulose or chitin, such as GH6, GH13, GH19, AA4, and CBM56. We further analyzed the sequence and structural characteristics of its three GH19 enzymes to understand their potential functions. The results revealed that myxobacterial GH19 enzymes are evolutionarily divided into two clades with different appended modules, and their different amino acid compositions in the substrate binding pockets lead to the differences in molecular surface electrostatic potentials, which may, in turn, affect their substrate selectivity and biological functions. Our study is helpful for further understanding the biological functions and catalytic mechanisms of myxobacterial CAZymes.
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•ViLPMO10B is a myxobacterial C1-oxidizing cellulose-active LPMO.•ViLPMO10B synergyzes with commercial cellulase in degradation of crop straws.•ViLPMO10B reduces the degree of ...polymerization of crop straw cellulose.•ViLPMO10B has application potential in the utilization of agricultural waste.
Myxobacteria are soil microorganisms with the ability to break down biological macromolecules due to the secretion of a large number of extracellular enzymes, but there has been no research report on myxobacterial lytic polysaccharide monooxygenases (LPMOs). In this study, two LPMO10s, ViLPMO10A and ViLPMO10B, from myxobacterium Vitiosangium sp. GDMCC 1.1324 were characterized. Of which, ViLPMO10B is a C1-oxidizing cellulose-active LPMO. Moreover, ViLPMO10B could decrease the degree of polymerization of crop straws cellulose and synergize with commercial cellulase to promote the saccharification. When the weight ratio of commercial cellulase to ViLPMO10B was 9:1, the conversion efficiency of corn stalk, sugarcane bagasse, and rice straw into reducing sugar was improved by 17%, 16%, and 22%, respectively, compared with commercial cellulase without ViLPMO10B. These results indicate that ViLPMO10B has the potential to be a component of a high-efficient cellulase cocktail and has application value in the saccharification of agricultural residual biomasses.
Up to 25,000 people die each year from resistant infections in Europe alone, with increasing incidence. It is estimated that a continued rise in bacterial resistance by 2050 would lead up to 10 ...million annual deaths worldwide, exceeding the incidence of cancer deaths. Although the design of new antibiotics is still one way to tackle the problem, pharmaceutical companies investigate far less into new drugs than 30 years ago. Incorporation of antibiotics into nanoparticle drug carriers (“nanoantibiotics”) is currently investigated as a promising strategy to make existing antibiotics regain antimicrobial strength and overcome certain types of microbial drug resistance. Many of these synthetic systems enhance the antimicrobial effect of drugs by protecting antibiotics from degradation and reducing their side effects. Nevertheless, they often cannot selectively target pathogenic bacteria and – due to their synthetic origin – may induce side-effects themselves.
In this work, we present the characterisation of naturally derived outer membrane vesicles (OMVs) as biocompatible and inherently antibiotic drug carriers. We isolated OMVs from two representative strains of myxobacteria, Cystobacter velatus Cbv34 and Sorangiineae species strain SBSr073, a bacterial order with the ability of lysing other bacterial strains and currently investigated as sources of new secondary metabolites. We investigated the myxobacterias' inherent antibacterial properties after isolation by differential centrifugation and purification by size-exclusion chromatography. OMVs have an average size range of 145–194 nm. We characterised their morphology by electron cryomicroscopy and found that OMVs are biocompatible with epithelial cells and differentiated macrophages. They showed a low endotoxin activity comparable to those of control samples, indicating a low acute inflammatory potential. In addition, OMVs showed inherent stability under different storage conditions, including 4 °C, −20 °C, −80 °C and freeze-drying. OMV uptake in Gram-negative model bacterium Escherichia coli (E. coli) showed similar to better incorporation than liposome controls, indicating the OMVs may interact with model bacteria via membrane fusion. Bacterial uptake correlated with antimicrobial activity of OMVs as measured by growth inhibition of E. coli. OMVs from Cbv34 inhibited growth of E. coli to a comparable extent as the clinically established antibiotic gentamicin. Liquid-chromatography coupled mass spectrometry analyses revealed the presence of cystobactamids in OMVs, inhibitors of bacterial topoisomerase currently studied to treat different Gram-negative and Gram-positive pathogens. This work, may serve as an important basis for further evaluation of OMVs derived from myxobacteria as novel therapeutic delivery systems against bacterial infections.
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