Broad-Spectrum Bioactivity of Chitosan N-acetylglucosaminohydrolase (Chitosan NAGH) Extracted from Bacillus ligniniphilus .

Background: The genus Bacillus has species with strains that produce Chitosan N-acetylglucosaminohydrolase (NAGH), a hydrolytic enzyme. Objective: A novel bacterium, Bacillus ligniniphilus , was characterized as producing Chitosan NAGH. This study further examine its antibiofilm properties and its possible uses against biofilm-producing bacteria. Methods: Various sea soil samples were evaluated for the presence of Chitosan NAGH. The chosen isolate, Bacillus ligniniphilus 61, was then used to extract and purify Chitosan NAGH using precipitation in ammonium sulfate followed by polyethylene glycol-treated dialysis and gel-permeation chromatography. Biofilm inhibition and antimicrobial activity of Chitosan NAGH was estimated against different bacterial species. Both gene expression profiling of biofilm-related genes and an extracellular polymeric substance (EPS) inhibition assay were performed. Results: The BL61 strain was able to produce much more Chitosan activity than the other strains, as the latter only exhibited antimicrobial activity at low concentration levels; however, they did show as antibiofilm agents at varying proportions. Chitosan NAGH caused a uniform decrease in EPS formation in each isolate. Many biofilm-related genes, e.g., IcaABCD , decreased, but genes related to autoinducer synthetase were not affected by Chitosan NAGH. EPS, which is responsible for polysaccharide formation, was underexpressed at 3-fold down. Conclusions: The current study results allow future researchers to look for better and newer compounds with the antibiofilm property that inhibits the formation of biofilm created by a wide range of bacteria without affecting their growth.