Growth of Carnobacterium divergens M35 and production of Divergicin M35 in snow crab by-product, a natural-grade medium

This work aimed to study the factors influencing the growth of Carnobacterium divergens strain M35 and its ability to produce a new class IIa bacteriocin (divergicin M35) in various synthetic media and in medium supplemented with snow crab hepatopancreas (SCH), a natural-grade by-product of crustacean processing. C. divergens M35 growth and bacteriocin production in SCH-supplemented medium was evaluated at different temperatures in batch fermentations and under controlled pH. C. divergens M35 was shown to grow well in SCH medium at tested temperatures between 4 and 30 °C, except at 37 °C. Maximum divergicin M35 production was obtained after 10 h of growth in SCH medium at 25 and 30 °C with a total activity of 3.7 × 10⁴ AU mL⁻¹. Less growth was observed at 37 °C, for which a total bacteriocin activity of only 256 AU mL⁻¹ was obtained. The production of divergicin M35 was greatly influenced by the medium composition, especially by the type of added carbon source. The best production of divergicin M35 in SCH medium was observed at a controlled pH of 7.0. This study describes the optimal parameters for the growth of C. divergens M35 and production of divergicin M35 and demonstrates the effectiveness of the marine by-product as a medium supplement for this culture.