Difficidin and oxydifficidin: novel broad spectrum antibacterial antibiotics produced by Bacillus subtilis. I. Production, taxonomy and antibacterial activity.
ABSTRACT Difficidin and oxydifficidin, two novel macrocyclic polyene lactone phosphate esters were discovered in fermentation broths of each of two strains of Bacillus subtilis: ATCC 39320 and ATCC 39374. Difficidin and oxydifficidin each showed a broad spectrum of activity against aerobic and anaerobic bacteria. Many of the susceptible aerobes and anaerobes were human pathogens resistant to one or more antibiotics. Difficidin and oxydifficidin when administered intraperitoneally protected mice against an otherwise lethal bacteremia caused by Klebsiella pneumoniae (ED50 in mg/kg of 1.31 and 15.6 respectively). Neither difficidin nor oxydifficidin were effective when administered via the subcutaneous route.
SourceAvailable from: Walaa Kamel Mousa[Show abstract] [Hide abstract]
ABSTRACT: The plant is an attractive versatile home for diverse associated microbes. A subset of these microbes produces a diversity of anti-microbial natural products including polyketides, non-ribosomal peptides, terpenoids, heterocylic nitrogenous compounds, volatile compounds, bacteriocins, and lytic enzymes. In recent years, detailed molecular analysis has led to a better understanding of the underlying genetic mechanisms. New genomic and bioinformatic tools have permitted comparisons of orthologous genes between species, leading to predictions of the associated evolutionary mechanisms responsible for diversification at the genetic and corresponding biochemical levels. The purpose of this review is to describe the biodiversity of biosynthetic genes of plant-associated bacteria and fungi that encode selected examples of antimicrobial natural products. For each compound, the target pathogen and biochemical mode of action are described, in order to draw attention to the complexity of these phenomena. We review recent information of the underlying molecular diversity and draw lessons through comparative genomic analysis of the orthologous coding sequences (CDS). We conclude by discussing emerging themes and gaps, discuss the metabolic pathways in the context of the phylogeny and ecology of their microbial hosts, and discuss potential evolutionary mechanisms that led to the diversification of biosynthetic gene clusters.Frontiers in Plant Science 04/2015; 6:231. DOI:10.3389/fpls.2015.00231 · 3.64 Impact Factor
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ABSTRACT: Bacillus and related genera in the Bacillales within the Firmicutes harbor a variety of secondary metabolite gene clusters encoding polyketide synthases and non-ribosomal peptide synthetases responsible for remarkable diverse number of polyketides (PKs) and lipopeptides (LPs). These compounds may be utilized for medical and agricultural applications. Here, we summarize the knowledge on structural diversity and underlying gene clusters of LPs and PKs in the Bacillales. Moreover, we evaluate by using published prediction tools the potential metabolic capacity of these bacteria to produce type I PKs or LPs. The huge sequence repository of bacterial genomes and metagenomes provides the basis for such genome-mining to reveal the potential for novel structurally diverse secondary metabolites. The otherwise cumbersome task to isolate often unstable PKs and deduce their structure can be streamlined. Using web based prediction tools, we identified here several novel clusters of PKs and LPs from genomes deposited in the database. Our analysis suggests that a substantial fraction of predicted LPs and type I PKs are uncharacterized, and their functions remain to be studied. Known and predicted LPs and PKs occurred in the majority of the plant associated genera, predominantly in Bacillus and Paenibacillus. Surprisingly, many genera from other environments contain no or few of such compounds indicating the role of these secondary metabolites in plant-associated niches.03/2015; 58. DOI:10.1016/j.csbj.2015.03.003
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ABSTRACT: The Bacillus amyloliquefaciens subsp. plantarum strain UCMB5113 is a Gram-positive rhizobacterium that can colonize plant roots and stimulate plant growth and defense based on unknown mechanisms. This reinforcement of plants may provide protection to various forms of biotic and abiotic stress. To determine the genetic traits involved in the mechanism of plant-bacteria association, the genome sequence of UCMB5113 was obtained by assembling paired-end Illumina reads. The assembled chromosome of 3,889,532 bp was predicted to encode 3,656 proteins. Genes that potentially contribute to plant growth promotion such as indole-3-acetic acid (IAA) biosynthesis, acetoin synthesis and siderophore production were identified. Moreover, annotation identified putative genes responsible for non-ribosomal synthesis of secondary metabolites and genes supporting environment fitness of UCMB5113 including drug and metal resistance. A large number of genes encoding a diverse set of secretory proteins, enzymes of primary and secondary metabolism and carbohydrate active enzymes were found which reflect a high capacity to degrade various rhizosphere macromolecules. Additionally, many predicted membrane transporters provides the bacterium with efficient uptake capabilities of several nutrients. Although, UCMB5113 has the possibility to produce antibiotics and biosurfactants, the protective effect of plants to pathogens seems to be indirect and due to priming of plant induced systemic resistance. The availability of the genome enables identification of genes and their function underpinning beneficial interactions of UCMB5113 with plants.PLoS ONE 08/2014; 9(8). DOI:10.1371/journal.pone.0104651 · 3.53 Impact Factor