fengycin and bacillaene

Bacillus subtilis currently encompasses four subspecies, Bacillus subtilis subsp. subtilis, Bacillus subtilis subsp. inaquosorum, Bacillus subtilis subsp. spizizenii and Bacillus subtilis subsp. stercoris. Several studies based on genomic comparisons have suggested these subspecies should be promoted to species status. Previously, one of the main reasons for leaving them as subspecies was the lack of distinguishing phenotypes. In this study, we used comparative genomics to determine the genes unique to each subspecies and used these to lead us to the unique phenotypes. The results show that one difference among the subspecies is they produce different bioactive secondary metabolites. B. subtilis subsp. spizizenii is shown conserve the genes to produce mycosubtilin, bacillaene and 3,3'-neotrehalosadiamine. B. subtilis subsp. inaquosorum is shown conserve the genes to produce bacillomycin F, fengycin and an unknown PKS/NRPS cluster. B. subtilis subsp. stercoris is shown conserve the genes to produce fengycin and an unknown PKS/NRPS cluster. While B. subtilis subsp. subtilis is shown to conserve the genes to produce 3,3'-neotrehalosadiamine. In addition, we update the chemotaxonomy and phenotyping to support their promotion to species status.

Topics: Bacillus subtilis; Genome, Bacterial; Lipopeptides; Lipoproteins; Peptides, Cyclic; Polyenes

In this study, we identified a new Bacillus strain isolated from an Algerian salty lake that produces metabolites that are active against Gram-positive and Gram-negative bacteria, as well as fungal pathogens. The draft genome sequence of the strain is presented herein. Genome sequence analysis identified the strain to be B. amyloliquefaciens subspecies plantarum F11, and showed that the strain carries the gene clusters for the production of a number of bioactive and surface-active compounds. These include the lipopeptides surfactin and fengycin, antibacterial polyketides macrolactin and bacillaene, and a putative novel lanthipeptide, among others. Through an activity-guided purification method using hydrophobic interaction chromatographic techniques, we confirmed the ability of the strain to produce fengycin lipopeptides. The identities of the isolated fengycin homologs were ascertained through tandem mass spectrometry.

Topics: Algeria; Anti-Bacterial Agents; Antifungal Agents; Bacillus amyloliquefaciens; Comparative Genomic Hybridization; Genome, Bacterial; Lakes; Lipopeptides; Microbial Sensitivity Tests; Polyenes; Polyketides; Saline Waters; Surface-Active Agents

Bacillus subtilis XF-1 is a gram-positive, plant-associated bacterium that stimulates plant growth and produces secondary metabolites that suppress soil-borne plant pathogens. In particular, it is especially highly efficient at controlling the clubroot disease of cruciferous crops. Its 4,061,186-bp genome contains an estimated 3853 protein-coding sequences and the 1155 genes of XF-1 are present in most genome-sequenced Bacillus strains: 3757 genes in B. subtilis 168, and 1164 in B. amyloliquefaciens FZB42. Analysis using the Cluster of Orthologous Groups database of proteins shows that 60 genes control bacterial mobility, 221 genes are related to cell wall and membrane biosynthesis, and more than 112 are genes associated with secondary metabolites. In addition, the genes contributed to the strain's plant colonization, bio-control and stimulation of plant growth. Sequencing of the genome is a fundamental step for developing a desired strain to serve as an efficient biological control agent and plant growth stimulator. Similar to other members of the taxon, XF-1 has a genome that contains giant gene clusters for the non-ribosomal synthesis of antifungal lipopeptides (surfactin and fengycin), the polyketides (macrolactin and bacillaene), the siderophore bacillibactin, and the dipeptide bacilysin. There are two synthesis pathways for volatile growth-promoting compounds. The expression of biosynthesized antibiotic peptides in XF-1 was revealed by matrix-assisted laser desorption/ionization-time of flight mass spectrometry.

Topics: Anti-Bacterial Agents; Antifungal Agents; Bacillus subtilis; Biological Control Agents; Biosynthetic Pathways; Dipeptides; Genes, Bacterial; Genome, Bacterial; Lipopeptides; Molecular Sequence Data; Multigene Family; Oligopeptides; Plant Development; Plant Diseases; Plants; Polyenes; Polyketides; Secondary Metabolism; Sequence Analysis, DNA; Siderophores

Phytopathogenic fungi affecting crop and post-harvested vegetables are a major threat to food production and food storage. To face these drawbacks, producers have become increasingly dependent on agrochemicals. However, intensive use of these compounds has led to the emergence of pathogen resistance and severe negative environmental impacts. There are also a number of plant diseases for which chemical solutions are ineffective or non-existent as well as an increasing demand by consumers for pesticide-free food. Thus, biological control through the use of natural antagonistic microorganisms has emerged as a promising alternative to chemical pesticides for more rational and safe crop management.. The genome of the plant-associated B. amyloliquefaciens GA1 was sample sequenced. Several gene clusters involved in the synthesis of biocontrol agents were detected. Four gene clusters were shown to direct the synthesis of the cyclic lipopeptides surfactin, iturin A and fengycin as well as the iron-siderophore bacillibactin. Beside these non-ribosomaly synthetised peptides, three additional gene clusters directing the synthesis of the antibacterial polyketides macrolactin, bacillaene and difficidin were identified. Mass spectrometry analysis of culture supernatants led to the identification of these secondary metabolites, hence demonstrating that the corresponding biosynthetic gene clusters are functional in strain GA1. In addition, genes encoding enzymes involved in synthesis and export of the dipeptide antibiotic bacilysin were highlighted. However, only its chlorinated derivative, chlorotetaine, could be detected in culture supernatants. On the contrary, genes involved in ribosome-dependent synthesis of bacteriocin and other antibiotic peptides were not detected as compared to the reference strain B. amyloliquefaciens FZB42.. The production of all of these antibiotic compounds highlights B. amyloliquefaciens GA1 as a good candidate for the development of biocontrol agents.

Topics: Anti-Bacterial Agents; Bacillus; Lactones; Lipopeptides; Macrolides; Multigene Family; Oligopeptides; Peptides, Cyclic; Pest Control, Biological; Phylogeny; Polyenes

A new method is described to remove and separate biosurfactants from complex mixtures by compressing and harvesting the liquid surface layer. This method was applied to Bacillus subtilis cultures, in which the lipopeptide antibiotic fengycin as well as the polyketide antibiotic bacillaene were produced. The automated harvesting and collection in a custom-built glass body called 'flounder' was repeated several hundred times. The fengycin concentration in the fractions was found to be four times higher than in the culture centrifugate. Of the overall fengycin, 50% (w/w) were recovered after 300 cycles, 95% (w/w) after 800 harvesting cycles. A separation of fengycin from the less surface-active bacillaene could be achieved due to stronger surface activity of fengycin. The ratio of partition coefficients of fengycin and bacillaene was nine times higher compared to foam fractionation. A stepwise increase of the equilibrium surface tension in the centrifugate from 29 to 33 mN/m indicated a fractionated separation of different surface-active substances. The utilization of cell containing culture broth instead of centrifugate had only slight effects on separation efficiency. These results demonstrate the possibility to separate biosurfactants directly from cultivation without the use of extraction solvents or foam formation.

Topics: Adsorption; Anti-Bacterial Agents; Bacillus subtilis; Centrifugation; Chemical Fractionation; Industrial Microbiology; Lipopeptides; Lipoproteins; Polyenes; Surface Tension; Surface-Active Agents