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Bacillus subtilis K‐C3 isolated from Thai salted shrimp paste (Kapi): Its extracellular enzymes and use as a starter culture in Kapi production

Pongsetkul, Jaksuma, Benjakul, Soottawat, Sumpavapol, Punnanee, Vongkamjan, Kitiya, Osako, Kazufumi
Journal of food biochemistry 2018 v.42 no.6 pp. e12649
Bacillus subtilis, carboxylic ester hydrolases, chitinase, condiments, denaturing gradient gel electrophoresis, drying, enzyme activity, extracellular enzymes, fermentation, inoculum, pH, proteinases, proteolysis, shrimp, sodium chloride, starter cultures, Thailand
The growth and production of the extracellular enzymes, protease, lipase, and chitinase by Bacillus subtilis K‐C3, isolated from commercial Kapi, were determined. This strain was able to grow and produce enzymes effectively at 25–35°C and pH 6–8 in the presence of 10% NaCl. Changes in enzyme activities in Kapi, without inoculation and inoculated with B. subtilis K‐C3 at the levels of 10², 10⁴, and 10⁶ CFU/g of dry weight sample during Kapi production, were monitored. For Kapi without inoculation, B. subtilis K‐C3 was present after the drying process and remained throughout all processes as established by the PCR‐DGGE technique. For all the inoculated samples, B. subtilis K‐C3 bands were detected at all stages of Kapi processing, indicating its survival during the entire process. All the inoculated samples exhibited higher proteolytic, lipolytic, and chitinolytic activities, compared to the control. Therefore, B. subtilis K‐C3 could be used as a starter culture to enhance the fermentation of Kapi. PRACTICAL APPLICATIONS: Kapi, a traditional salted shrimp paste of Thailand, is a popular condiment used in many Thai dishes. Recently, B. subtilis K‐C3 has been isolated from commercial Kapi and the strain produced a wide range of extracellular enzymes including protease, lipase, and chitinase. It was also able to survive throughout all the Kapi production processes. Moreover, Kapi inoculated with this strain exhibited higher enzymatic activities, compared to the control (without inoculum). Therefore, the inoculation with B. subtilis K‐C3 seems to have the potential to accelerate the fermentation of Kapi.