Diversity Revealed by Targeted Amplicon Sequencing of Gene, Metabolic Comparisons and Antimicrobial Properties in an Undefined Mixed Starter Culture Used for Soft-Cheese Manufacture.

The undefined mixed starter culture (UMSC) is used in the manufacture of cheeses. Deciphering UMSC microbial diversity is important to optimize industrial processes. The UMSC was studied using culture-dependent and culture-independent based methods.

Complete Genome Sequence of the Polymyxin E (Colistin)-Producing sp. Strain B-LR.

bacteria are recovered from varied niches, including human lung, rhizosphere, marine sediments, and hemolymph. Paenibacilli can have plant growth-promoting activities and be antibiotic producers. They can produce exopolysaccharides and enzymes of industrial interest.

Characterization of the colistin (polymyxin E1 and E2) biosynthetic gene cluster.

Colistin is a mixture of polymyxin E1 and E2, bactericidal pentacationic lipopeptides used to treat infections caused by Gram-negative pathogens such as Pseudomonas aeruginosa and Klebsiella pneumoniae. Industrial production of colistin is obtained by a fermentation process of the natural producer Paenibacillus polymyxa var colistinus. NonRibosomal peptide synthetases (NRPS) coding the biosynthesis of polymyxins A, B and P have been recently described, rendering thereof the improvement of their production possible.

Novel nonribosomal peptide synthetase (NRPS) genes sequenced from intertidal mudflat bacteria.

Nonribosomal peptide synthetases (NRPS) are actively sought out, due to pharmacologically important activities of their metabolites. In marine environment, the most prevalent nonribosomal peptide antibiotic producers are sponges inhabiting microorganisms. Conversely, strains from marine sediments and more especially from intertidal mudflats have not been extensively screened for the presence of new NRPS.

A Novel Depsipeptide Produced by Paenibacillus alvei 32 Isolated from a Cystic fibrosis Patient.

The important viscosity of the respiratory tract mucus of Cystic fibrosis (CF) patients impairs the mucociliary transport system and allows the growth of numerous micro-organisms. Among them, Pseudomonas aeruginosa and Staphylococcus aureus are known to be responsible for pulmonary infections. We imagined that CF microflora could also harbour micro-organisms naturally equipped to compete with these pathogens.

Peptides released from acid goat whey by a yeast-lactobacillus association isolated from cheese microflora.

Seven lactobacilli and a variety of microflora extracted from twenty five commercial cheeses were grown on unsupplemented acid goat whey and screened for their capacity to hydrolyse whey proteins [alpha-lactalbumin (alpha-la) and beta-lactoglobulin (beta-lg)] and to generate peptides. Fermentations were performed aerobically or anaerobically at 37 degrees C using crude or pre-heated whey (10 min at 65, 75 or 85 degrees C). Under aerobic conditions, growth of lactobacilli was poor and protein hydrolysis did not occur.

Maturation by LctT is required for biosynthesis of full-length lantibiotic lacticin 481.

In lantibiotic lacticin 481 biosynthesis, LctT cleaves the precursor peptide and exports mature lantibiotic. Matrix-assisted laser desorption ionization-time of flight mass spectrometry revealed that a truncated form of lacticin 481 is produced in the absence of LctT or after cleavage site inactivation. Production of truncated lacticin 481 is 4-fold less efficient, and its specific activity is about 10-fold lower.

Bacteriocin detection from whole bacteria by matrix-assisted laser desorption ionization-time of flight mass spectrometry.

Class I bacteriocins (lantibiotics) and class II bacteriocins are antimicrobial peptides secreted by gram-positive bacteria. Using two lantibiotics, lacticin 481 and nisin, and the class II bacteriocin coagulin, we showed that bacteriocins can be detected without any purification from whole producer bacteria grown on plates by matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF-MS). When we compared the results of MALDI-TOF-MS performed with samples of whole cells and with samples of crude supernatants of liquid cultures, the former samples led to more efficient bacteriocin detection and required less handling.