Enzymatic activity of Bacillus paralicheniformis T7 strain and its application in cheese production

Аннотация

Background and Aim. The increasing demand for inexpensive milk coagulants stimulates the search for new sources of milk-forming enzymes among proteolytic microorganisms. The aim of this work was to isolate a strain with proteolytic activity.

Materials and Methods. In the present study, a proteolytic strain of Bacillus paralicheniformis T7 was isolated and identified. By culturing B. paralicheniformis T7 for three days on feather medium, an enzymatic extract with proteolytic activity of 715.7 ± 40.2U/mL was obtained. In addition to proteolytic activity, the B. paralicheniformis T7 strain also exhibited amylase (176.1 ± 16.3), esterase (24.3 ± 0.4), lipase (17.5 ± 0.8), and phosphatase (11.9 ± 0.6) activities.

Results. Zymographic analysis using casein showed that the extract contained caseinolytic proteases. Proteases from B. paralicheniformis T7 completely hydrolyzed of 1 mg casein in 90 s. Six proteases, as well as esterase, amylase, phosphatase were identified in the extract by HPLC-Q/TOF analysis. In addition to caseinolytic activity, B. paralicheniformis extract has milk-clotting activity, which was 12 and 23 U/mL for cow's and ewes' milk, respectively. Cheese was produced from fresh cow's milk using the enzymatic extract, with a yield of 17%.

Conclusion. The use of the B. paralicheniformis T7 strain as a new source of proteolytic enzymes, and its proteases as milk-clotting enzymes in the cheese-making industry, appears promising.