文献类型：期刊文献

英文题名：Two-Step Bioprocess for Reducing Nucleus Degradation in Phytosterol Bioconversion by Mycobacterium neoaurum NwIB-R10hsd4A

作者：Wang, Xuedong[1];Hua, Chaolong[1];Xu, Xinwei[1];Wei, Dongzhi[1]

机构：[1]East China Univ Sci & Technol, State Key Lab Bioreactor Engn, 130 Meilong Rd, Shanghai 200237, Peoples R China

年份：2019

卷号：188

期号：1

起止页码：138

外文期刊名：APPLIED BIOCHEMISTRY AND BIOTECHNOLOGY

收录：;EI(收录号：20184406013844);WOS:【SCI-EXPANDED(收录号:WOS:000467534600011)】；

基金：This study was funded by the National Natural Science Foundation of China (No. 21276083, 31570079).

语种：英文

外文关键词：3-Ketosteroid-(1)-dehydrogenase; Mycobacterium neoaurum; Nucleus degradation; Two-step bioprocess; 4-Androstene-3; 17-dione

摘要：In order to obtain high 4-androstene-3,17-dione (AD) yield, nucleus degradation needs to be avoided during phytosterol bioconversion process with Mycobacterium neoaurum NwIB-R10(hsd4A). 3-Ketosteroid-(1)-dehydrogenase (KstD) catalyzes 1,2-desaturation of steroids and is a key enzyme involved in steroid nucleus oxidation. Heterogeneous expression and characterization of two KstDs (KstD2, KstD3) from M. neoaurum NwIB-R10(hsd4A) showed that their activities were inhibited by shifting temperature from 30 to 37 degrees C. However, the total activities of KstD2 and KstD3 were replenished when M. neoaurum NwIB-R10(hsd4A) was cultured at 37 degrees C because the transcription levels of kstD2 and kstD3 were upregulated 1.61- and 1.43-fold respectively compared with the cultivation at 30 degrees C. As the optimal temperature for cell growth was 30 degrees C, we developed a two-step bioprocess, cell culture at 30 degrees C and bioconversion with resting cells at 37 degrees C avoiding higher transcriptional level of kstD2 and kstD3. This process repressed the activities of KstDs, resulted in the decrease of 1,2-desaturation products, and reduced the nucleus degradation (17.6%). AD production increased to 24.7gl(-1) at higher substrate concentration (50gl(-1)). These results indicated that the two-step bioprocess was potential in phytosterol biotransformation industrially.