Abstract：
BACKGROUND: Research on the co-production of multiple enzymes by Bacillus velezensis as a novel species is still a topic that needs to be studied. This study aimed to investigate the fermentation characteristics of B. velezensis D6 co-producing α-amylase and protease and to explore their enzymatic properties and applications in fermentation.
RESULTS: The maximum co-production of α-amylase and protease reached 13.13 ± 0.72 and 2106.63 ± 64.42 U mL-1, respectively, under the optimal fermented conditions (nutrients: 20.0 g L-1 urea, 20.0 g L-1 glucose, 0.7 g L-1 MnCl2; incubation conditions: initial pH 7.0, temperature 41 °C, 8% inoculation size and 30% working volume). Moreover, the genetic co-expression of α-amylase and protease increased from 0 to 24 h and then decreased after 36 h at the transcriptional level, which coincided with the growth trend of B. velezensis D6. The optimal reaction temperature of α-amylase was 55-60 °C, while that of protease was 35-40 °C. The activities of α-amylase and protease were retained by over 80% after thermal treatment (90 °C, 1 h), which indicated that two enzymes co-produced by B. velezensis D6 demonstrated excellent thermal stability. Moreover, the two enzymes were stable over a wide pH range (pH 4.0-8.0 for α-amylase; pH 4.0-9.0 for protease). Finally, the degrees of hydrolysis of corn, rice, sorghum and soybeans by α-amylase from B. velezensis D6 reached 44.95 ± 2.95%, 57.16 ± 2.75%, 52.53 ± 4.01% and 20.53 ± 2.42%, respectively, suggesting an excellent hydrolysis effect on starchy raw materials. The hydrolysis degrees of mackerel heads and soybeans by protease were 43.93 ± 2.19% and 26.38 ± 1.72%, respectively, which suggested that the protease from B. velezensis D6 preferentially hydrolyzed animal-based protein.
CONCLUSIONS: This is a systematic study on the co-production of α-amylase and protease by B. velezensis D6, which is crucial in widening the understanding of this species co-producing multi-enzymes and in exploring its potential application. © 2024 Society of Chemical Industry.
RESULTS: The maximum co-production of α-amylase and protease reached 13.13 ± 0.72 and 2106.63 ± 64.42 U mL-1, respectively, under the optimal fermented conditions (nutrients: 20.0 g L-1 urea, 20.0 g L-1 glucose, 0.7 g L-1 MnCl2; incubation conditions: initial pH 7.0, temperature 41 °C, 8% inoculation size and 30% working volume). Moreover, the genetic co-expression of α-amylase and protease increased from 0 to 24 h and then decreased after 36 h at the transcriptional level, which coincided with the growth trend of B. velezensis D6. The optimal reaction temperature of α-amylase was 55-60 °C, while that of protease was 35-40 °C. The activities of α-amylase and protease were retained by over 80% after thermal treatment (90 °C, 1 h), which indicated that two enzymes co-produced by B. velezensis D6 demonstrated excellent thermal stability. Moreover, the two enzymes were stable over a wide pH range (pH 4.0-8.0 for α-amylase; pH 4.0-9.0 for protease). Finally, the degrees of hydrolysis of corn, rice, sorghum and soybeans by α-amylase from B. velezensis D6 reached 44.95 ± 2.95%, 57.16 ± 2.75%, 52.53 ± 4.01% and 20.53 ± 2.42%, respectively, suggesting an excellent hydrolysis effect on starchy raw materials. The hydrolysis degrees of mackerel heads and soybeans by protease were 43.93 ± 2.19% and 26.38 ± 1.72%, respectively, which suggested that the protease from B. velezensis D6 preferentially hydrolyzed animal-based protein.
CONCLUSIONS: This is a systematic study on the co-production of α-amylase and protease by B. velezensis D6, which is crucial in widening the understanding of this species co-producing multi-enzymes and in exploring its potential application. © 2024 Society of Chemical Industry.
摘要：
背景：关于velezensis芽孢杆菌作为一种新型物种共同生产多种酶的研究仍然是一个需要研究的课题。本研究旨在研究VelezensisD6共产α-淀粉酶和蛋白酶的发酵特性,探讨其酶学性质及其在发酵中的应用。
结果：α-淀粉酶和蛋白酶的最大联产量分别达到13.13±0.72和2106.63±64.42UmL-1，在最佳发酵条件下（营养成分：20.0gL-1尿素，20.0gL-1葡萄糖，0.7gL-1MnCl2；孵育条件：初始pH7.0，温度41°C，8%接种量和30%工作体积)。此外，在转录水平上，α-淀粉酶和蛋白酶的基因共表达从0到24小时增加，然后在36小时后降低，与VelezensisD6的生长趋势相吻合。α-淀粉酶的最佳反应温度为55-60℃,而蛋白酶的温度为35-40℃。热处理后，α-淀粉酶和蛋白酶的活性保留了80％以上（90°C，1h),这表明维氏芽孢杆菌D6共同产生的两种酶表现出优异的热稳定性。此外，这两种酶在很宽的pH范围内稳定（α-淀粉酶的pH4.0-8.0；蛋白酶的pH4.0-9.0）。最后,玉米的水解程度，大米,高粱和大豆的α-淀粉酶来自维氏芽孢杆菌D6达到44.95±2.95%，57.16±2.75%，52.53±4.01%和20.53±2.42%，分别,表明对淀粉原料具有优异的水解效果。鱼头和大豆的蛋白酶水解度分别为43.93±2.19%和26.38±1.72%,分别,这表明来自维氏芽孢杆菌D6的蛋白酶优先水解动物基蛋白。
结论：这是关于维氏芽孢杆菌D6共产α-淀粉酶和蛋白酶的系统研究，这对于扩大对该物种共产多酶的认识和探索其潜在应用至关重要。©2024化学工业学会。
结果：α-淀粉酶和蛋白酶的最大联产量分别达到13.13±0.72和2106.63±64.42UmL-1，在最佳发酵条件下（营养成分：20.0gL-1尿素，20.0gL-1葡萄糖，0.7gL-1MnCl2；孵育条件：初始pH7.0，温度41°C，8%接种量和30%工作体积)。此外，在转录水平上，α-淀粉酶和蛋白酶的基因共表达从0到24小时增加，然后在36小时后降低，与VelezensisD6的生长趋势相吻合。α-淀粉酶的最佳反应温度为55-60℃,而蛋白酶的温度为35-40℃。热处理后，α-淀粉酶和蛋白酶的活性保留了80％以上（90°C，1h),这表明维氏芽孢杆菌D6共同产生的两种酶表现出优异的热稳定性。此外，这两种酶在很宽的pH范围内稳定（α-淀粉酶的pH4.0-8.0；蛋白酶的pH4.0-9.0）。最后,玉米的水解程度，大米,高粱和大豆的α-淀粉酶来自维氏芽孢杆菌D6达到44.95±2.95%，57.16±2.75%，52.53±4.01%和20.53±2.42%，分别,表明对淀粉原料具有优异的水解效果。鱼头和大豆的蛋白酶水解度分别为43.93±2.19%和26.38±1.72%,分别,这表明来自维氏芽孢杆菌D6的蛋白酶优先水解动物基蛋白。
结论：这是关于维氏芽孢杆菌D6共产α-淀粉酶和蛋白酶的系统研究，这对于扩大对该物种共产多酶的认识和探索其潜在应用至关重要。©2024化学工业学会。
