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.
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ABSTRACT: Acetylcholinesterase (AChE) inhibitors or anticholinesterases reduce the activity of enzyme acetylcholinesterase that degrades the neurotransmitter acetylcholine in the brain. The inhibitors have a significant pharmacological role in neurodegenerative diseases like Alzheimer's and Parkinson's etc. Although plants have been a significant source of these compounds, there are very few sporadic reports of microorganisms producing such inhibitors. Anticholinesterase activity in bacterial associates of marine soft corals and sponges were not previously reported. We screened 887 marine bacteria for the presence of acetylcholinesterase inhibitors, in a microplate based assay, and found that 140 (15.8%) of them inhibit the electric eel enzyme acetylcholinesterase. Majority of the active isolates were bacterial associates of soft corals followed by sediment isolates while most of the potent inhibitors belonged to the bacterial associates of marine sponges. Maximum inhibition (54%) was exhibited by a bacterial strain M18SP4P (ii), isolated from the marine sponge Fasciospongia cavernosa. Based on phenotypic characterization and 16S rDNA sequencing, the strain was identified as Bacillus subtilis - revealing yet another activity in a strain of the model organism that is considered to be a cell factory. TLC bioautography of the methanol extract of this culture, showed the presence of two major components having this activity, when compared to Galanthamine, the positive control. From the results of our study, we conclude that acetylcholinesterase inhibitors are quite prevalent in marine bacteria, particularly the bacterial associates of marine invertebrates. Several potential AChE inhibitors in marine bacteria are waiting to be discovered to provide easily manipulable natural sources for the mass production of these therapeutic compounds.Microbial Cell Factories 02/2014; 13(1):24. · 3.31 Impact Factor
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ABSTRACT: AIMS: To identify and screen dominant Bacillus spp. strains isolated from Bikalga, fermented seeds of Hibiscus sabdariffa for their antimicrobial activities in BHI medium and in a H. sabdariffa seed based medium. Further to characterize the antimicrobial substances produced. METHODS AND RESULTS: The strains were identified by gyrB gene sequencing and phenotypic tests as B. amyloliquefaciens subsp. plantarum. Their antimicrobial activity was determined by the agar spot and well assay, being inhibitory to a wide range of Gram positive and Gram negative pathogenic bacteria and fungi. Antimicrobial activity against Bacillus cereus was produced in H. sabdariffa seeds based medium. PCR results revealed that the isolates have potential for the lipopeptides iturin, fengycin, surfactin, the polyketides difficidin, macrolantin, bacillaene and the dipeptide bacilysin production. Ultra High Performance Liquid Chromatography-Time of Flight Mass Spectrometry analysis of antimicrobial substance produced in BHI broth allowed identification of iturin, fengycin and surfactin. CONCLUSIONS: The Bacillus amyloliquefaciens subsp. plantarum exhibited broad spectrum antifungal and antibacterial properties. They produced several lipopeptide antibiotics, and showed good potential for biological control of SIGNIFICANCE AND IMPACT OF STUDY: Pathogenic bacteria often occur in spontaneous food fermentations. This is the first report to identify indigenous B. amyloliquefaciens subsp. plantarum strains as potential protective starter cultures for safeguarding Bikalga. This article is protected by copyright. All rights reserved.Journal of Applied Microbiology 04/2013; · 2.20 Impact Factor
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ABSTRACT: Paenibacillus sp. F6-B70 was selected from several dozens of isolates with activity against methicillin-resistant Staphylococcus aureus using a 16S rDNA-based screening method. F6-B70 contained polyketide synthase (PKS) and non-ribosomal peptide synthetase (NRPS) clusters in its genome revealed by PCR amplification of conserved adenylation and ketosynthase (KS) domains. Phylogenetic data suggested that the strain hosts trans-AT PKSs and their product may be a branched molecule. An antibiotic was subsequently isolated from the methanol extract of F6-B70 cells. The molecular formula of the antibiotic was deduced to be C(33) H(50) NaO(6) ([M + Na](+) , m/z 565.3505) by analysis of electrospray ionization mass spectral data. Elucidation of the structure by nuclear magnetic resonance and infrared spectroscopy revealed that the active compound, paenimacrolidin (PAM), was a novel 22-membered macrolide with side-chains. The new antibiotic, mainly as a bacteriostatic agent, inhibits a couple of multidrug-resistant Staphylococcus sp. strains. The antibiotic capacity of PAM was compromised by its instability, which can be overcome significantly with addition of an anti-oxidant. To our knowledge, this is the first report of the isolation of an active macrolide from paenibacilli, which may be a promising source of novel antibiotics.Microbial Biotechnology 08/2010; 4(4):491-502. · 3.21 Impact Factor