Abstract：Selenium is an essential trace element for organisms, and selenomethionine(SeMet) is one primary chemical form in which animals obtain selenium from natural food. To screen candidate genes associated with SeMet biosynthesis in Bacillus subtilis, in this study, 6 strains of B. subtilis were isolated and identified from selenium-enriched soil samples collected in Enshi. The selenium tolerance of B. subtilis of BsES(B. subtilis from Enshi) was determined to be stronger than those of BsJZ(B. subtilis from Jingzhou) and the type strain of Bs168(B. subtilis subsp. subtilis str. 168) using different doses of Na2SeO3, and 0.1 mg/mL Na2SeO3 was determined to be the optimal additive dose for selenium-enriched culture. High performance liquid chromatography-mass spectrometry(HPLC-MS) analysis showed that the SeMet synthesis ability of strain BsES08 was the strongest, with a synthesis amount of 8.90 µg/108CFU, which was 39.47% and 34.33% higher than that of the control strains Bs168 and BsJZ, respectively. qPCR was used to comparatively analyze the mRNA expression levels of 31 SeMet synthesis metabolism-related genes in the 6 isolated strains. Results showed that the expression levels of tusA2, tusA1, TrxRB, thiS, nifS, nasD, mrp, mmuM and metE3 genes in strain BsES08 were higher than those in the other strains, suggesting that these genes might be related to SeMet synthesis. Recombinant B. subtilis of BsES08-tusA1 and BsES08-TrxRB were constructed using the pHT43 expression vector to overexpress tusA1 and TrxRB gene, respectively. The SeMet synthesis amounts of the recombinant strains were 10.71 and 11.17 µg/108CFU, respectively, which were 24.90% and 30.23% higher than those of BsES08. In conclusion, a selenium-enriched strain B. subtilis, BsES08, was isolated from selenium-enriched soil in Enshi, which had a high tolerance to inorganic selenium and a high efficiency of organic selenium conversion. Nine candidate genes related to SeMet synthesis were identified. This study provides microbial resources and functional genes for the development and utilization of selenium-enriched probiotics.
吴敏, 李禾钱, 付涛, 刘欣, 高学军, 张明辉. 富硒枯草芽胞杆菌的分离及硒代蛋氨酸合成相关基因的筛选[J]. 农业生物技术学报, 2026, 34(8): 1750-1765.
WU Min, LI He-Qian, FU Tao, LIU Xin, GAO Xue-Jun, ZHANG Ming-Hui. Isolation of Selenium-enriched Bacillus subtilis and Screening of Genes Related to Selenomethionine Synthesis. 农业生物技术学报, 2026, 34(8): 1750-1765.
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