A two-stage oxygen supply control strategy for enhancing milk-clotting enzyme production by Bacillus amyloliquefaciens

Abstract

To enhance the yield and productivity of milkclotting enzyme (MCE) by Bacillus amyloliquefaciens, a two-stage oxygen supply control strategy was proposed and successfully applied in the MCE fermentation. During the first 16 h, K L a was controlled at 72.2 h -1 to obtain high cell growth rate (v) and MCE activity (MCA) productivity (r MCA ). Subsequently, K L a was controlled at 33.9 h -1 to maintain high specific MCA productivity (q MCA ). Using this strategy, MCA peaked at 36 h with the MCA of 6,590.41 SU ml -1 , which was 18 h earlier than other investigated processes. The concept and results described represent the basis of an industrial scale-up process to achieve high MCE yield, MCA productivity and MCA/proteolytic activity.

High Milk-Clotting Activity Expressed by the Newly Isolated Paenibacillus spp. Strain BD3526

“…The maximum MCA of 6470 ± 281 SU mL −1 was achieved in 30 mL broth in 250 mL flask at 20 h and 300 rpm, much higher than the peak MCA observed in 50 mL liquid in 250 mL flask at 300 rpm for 30 h (Figure 3). Our result was in agreement with that reported by Ding [18], who found the peak MCA was enhanced 1.33-fold and cultivation time was shortened by 18 h through a two-stage oxygen supply control strategy. The MCA expressed by BD3526 was much higher than most reported microorganisms in submerged fermentation (Table 1) [22,33,37,38,39,40,41,42].…”

“…Proteases from over 100 fungal sources have been reported to display milk-clotting activity (MCA) and fungal coagulants, especially those originated from Rhizomucor miehei , R. pusillus and Endothia parasitica , have already been widely used in commercial cheese-making [14]. In contrast, few commercial applications of bacterial coagulants have been reported, despite a marked increase in the documentation of bacterial proteases exerting MCA [15,16,17,18]. Recently, the milk-clotting proteases from Bacillus amyloliquefaciens and Bacillus spp.…”

Prebiotic, Probiotic, Antimicrobial, and Functional Food Applications of Bacillus amyloliquefaciens

“…The application of B. amyloliquefaciens in the hydrolysis of complex proteins in the food sector involves different strains. A study conducted on cheese fermentation shows that B. amyloliquefaciens D4 contributes a high proteolytic activity against alcohol insoluble milk proteins, which give less ripening time in cheese making and increase the hydrophilic property of the cheese. , Another strain of B. amyloliquefaciens JUN002 isolated from wheat bran has been used as a milk clotting agent, indicating that the wheat-based source can also be applied in the hydrolysis of gluten and other complex proteins …”

“…55,63 Another strain of B. amyloliquefaciens JUN002 isolated from wheat bran has been used as a milk clotting agent, indicating that the wheat-based source can also be applied in the hydrolysis of gluten and other complex proteins. 64 High-sulfur containing rapeseed meal, after oil extraction, contains less digestible proteins. The application of B. amyloliquefaciens CX-20 in the hydrolysis of this byproduct results in the formation of free water-soluble peptides and other compounds.…”

Regulation of Metabolic Flux in Lactobacillus casei for Lactic Acid Production by Overexpressed ldhL Gene with Two-Stage Oxygen Supply Strategy

“…Recently, the two-stage oxygen supply strategy (TOS) was proved to be an effective strategy for enhancement of enzymes and organic acids production [6,18,23]. Previous reports signified that the growth of some L. lactis strains can benefit from the presence of low oxygen levels.…”