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Identification and Characterization of a Vibrio cholerae Gene, mbaA, Involved in Maintenance of Biofilm Architecture. Natalia Bomchil, 2003.The formation of biofilms is thought to play a key role in the environmental survival of the marine bacterium Vibrio cholerae . Although the factors involved in V . cholerae attachment to abiotic surfaces have been extensively studied, relatively little is known about the mechanisms involved in the subsequent maturation of the biofilms . Here we report the identification of a novel gene, which we have named mbaA (for maintenance of biofilm architecture), that plays a role in the formation and maintenance of the highly organized three-dimensional architecture of V . cholerae El Tor biofilms . We demonstrate that although the absence of mbaA does not significantly affect the initial attachment of cells onto the surface, it leads to the formation of biofilms that lack the typical structure, including the pillars of cells separated by fluid-filled channels that are evident in mature wild-type biofilms . Microscopic analysis indicates that the absence of mbaA leads to an increase in the amount of extracellular matrix material in the biofilms . The predicted mbaA product is a member of a family of regulatory proteins, containing GGDEF and EAL domains, suggesting that MbaA regulates the synthesis of some component of the biofilm matrix . Hydrolysis of Casein-Derived Peptides  S1-Casein(f1-9) and ß-Casein(f193-209) by Lactobacillus helveticus Peptidase Deletion Mutants Indicates the Presence of a Previously Undetected Endopeptidase.Jeffrey E. Christensen, 2003.Peptides derived from hydrolysis of S1-casein(f1-9) [S1-CN(f1-9)] and ß-CN(f193-209) with cell extracts of Lactobacillus helveticus CNRZ32 and single-peptidase mutants ( pepC,
pepE,
pepN,
pepO, and
pepX) were isolated by using reverse-phase high-performance liquid chromatography and were characterized by mass spectrometry . The peptides identified suggest that there was activity of an endopeptidase, distinct from previously identified endopeptidases (PepE and PepO), with specificity for peptide bonds C terminal to Pro residues . Identification of hydrolysis products derived from a carboxyl-blocked form of ß-CN(f193-209) confirmed that the peptides were derived from the activity of an endopeptidase .
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