Liu Zhongmei, Gao Xinxing, Zhou Li, Cui Wenjing, Tian Yaping, Zhou Zhemin
Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, Jiangsu, People's Republic of China.
Can J Microbiol. 2017 Jun;63(6):516-524. doi: 10.1139/cjm-2016-0602. Epub 2017 Mar 3.
To investigate the physiological role of an extracellular aminopeptidase (BSAP168) encoded by the ywaD gene in Bacillus subtilis 168, we constructed the ywaD-deletion mutant (BS-AP-K). Compared with that of the wild-type strain, the maximum growth rate of BS-AP-K was reduced by 28% when grown in soybean protein medium at 37 °C, but not in Luria-Bertani medium. The impaired growth rate was more marked at higher temperature and could be compensated by supplementation of amino acid to the culture media. Further studies showed that in regards to the amino acid compositions and peptide distribution in the culture supernatants, there was an obvious difference between the culture supernatants of wild-type and BS-AP-K strains. In addition, another mutant strain (BS-AP-R) was constructed by replacing ywaD with ywaD-ΔPA to evaluate the effect of a protease-associated domain in BSAP168 on growth. All these findings indicated that BSAP168 played an important role in supplying the amino acids required for growth.
为了研究枯草芽孢杆菌168中ywaD基因编码的一种细胞外氨肽酶（BSAP168）的生理作用，我们构建了ywaD缺失突变体（BS-AP-K）。与野生型菌株相比，BS-AP-K在37℃的大豆蛋白培养基中生长时，其最大生长速率降低了28%，但在Luria-Bertani培养基中则没有。在较高温度下，生长速率受损更为明显，并且可以通过向培养基中补充氨基酸来补偿。进一步的研究表明，就培养上清液中的氨基酸组成和肽分布而言，野生型和BS-AP-K菌株的培养上清液之间存在明显差异。此外，构建了另一个突变菌株（BS-AP-R），用ywaD-ΔPA替换ywaD，以评估BSAP168中蛋白酶相关结构域对生长的影响。所有这些发现表明，BSAP168在提供生长所需的氨基酸方面发挥了重要作用。
