Isolation and Identification of Marine Bacillus and Determination of Its Digestive Enzyme Metabolites

Objective The study is aimed at isolating and identifying Bacillus which can produce digestive enzyme metabolites from marine organisms and environment, and providing probiotics for the development of its microecologics.

Method Samples were collected from the coastal waters of Leizhou Peninsula, and the isolated strains were obtained by high temperature treatment, enrichment culture, isolation and cultivation method. The isolated strains were identified by their colony morphology, cell structure, staining characteristics, biochemical test and 16S rRNA gene sequencing. The determination of protease, amylase and lipase activity in the metabolites of the isolated strains was detected by Folin phenol colorimetry, starch iodine colorimetry and olive oil emulsification method, respectively.

Result Forty three suspected Bacillus strains are identified from 22 samples. Eight strains of them with the strongest comprehensive activities of three digestive enzymes are screened out, and identified through biochemical test and 16S rRNA gene sequencing as three strains of Bacillus cereus, three strains of Bacillus siamensis, one strain of Bacillus tequilensis, and one strain of Bacillus xylanilyticus. Among them, Bacillus xylolylysine BC1 produces the highest lipase activity(52.13 U/mL), Bacillus cereus BC3 produces the highest protease activity(4.78 U/mL)and Bacillus Siamese BC6 produces the highest amylase activity (2.35 U/mL).

Conclusion Marine Bacillus producing digestive enzyme metabolites are screened out successfully.