Collagenolytic proteases from Bacillus subtilis B13 and B. siamensis S6 and their specificity toward collagen with low hydrolysis of myofibrils

To obtain proteases with high collagenolytic activity, 400 bacteria isolates were screened. The secreted proteases from Bacillus subtilis subsp. subtilis B13 (isolated from beef butchery) and B. siamemsis S6 (isolated from soil) which showed the two highest activity to hydrolyze collagen from bovine Achilles tendon were partially characterized. After enzyme fractionation, both enzymes had the optimum pH for the collagenolytic activity at pH 7.5. However, the optimum temperature of enzyme produced by S6 (60 °C) was higher than B13 (50 °C). The inhibitor study revealed that these proteases were mainly a member of serine proteases and some metalloproteases. Both enzymes were able to degrade collagen with multiple cleavage sites as observed by electrophoretic patterns. In contrast to papain and bromelain, these collagenolytic proteases showed strong hydrolysis toward collagen and elastin as well as beef intramuscular collagen with low beef myofibrillar protein degradation. Moreover, the lower digestion of myofibrillar protein and casein by these enzymes as compared with collagenase from Clostridium histolyticum were observed. These proteases could be applied as a meat tenderizer when collagen or connective tissue protein was responsible for the meat toughness. •Proteases from Bacillus subtilis B13 and B. siamensis S6 effectively degraded collagen.•A novel collagenolytic protease from B. siamensis was firstly reported.•Two collagenolytic proteases specifically hydrolyzed collagen and elastin than myofibrillar protein.•Proteases secreted by non-pathogenic strains could be potential meat tenderizer.