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sigL基因编码的产物σ54是许多重要代谢途径的转录因子。为研究sigL基因在苏云金芽胞杆菌中的功能,试验分别测定苏云金芽胞杆菌HD-73菌株和sigL基因缺失突变菌株在基本培养基中对不同碳氮源的利用。结果表明,出发菌株和sigL突变体都不能利用果糖、蔗糖、纤维二糖、柠檬酸作为唯一碳源;sigL突变菌株不能利用肌氨酸、亮氨酸、异亮氨酸、丝氨酸和缬氨酸为唯一氮源,说明sigL缺失可能阻碍这些氨基酸参与的代谢途径。β-半乳糖苷酶活性分析表明,调控肌氨酸代谢途径的soxR基因转录活性在sigL突变体中降低,说明sigL是通过调控编码肌氨酸氧化酶的基因簇(sox)而影响菌体对肌氨酸的利用。
Sigma54, a gene encoded by the sigL gene, is a transcription factor for many important metabolic pathways. In order to investigate the function of sigL gene in B. thuringiensis, the use of different carbon and nitrogen sources in the minimal medium for the determination of Bacillus thuringiensis HD-73 and sigL gene-deleted mutants was tested. The results showed that fructose, sucrose, cellobiose and citric acid were the only carbon sources for both the starting strain and the mutant sigL; sigL mutant strain could not utilize sarcosine, leucine, isoleucine, serine and valine As the sole nitrogen source, it shows that the absence of sigL may hinder the metabolic pathways involved in these amino acids. Analysis of β-galactosidase activity showed that the transcriptional activity of soxR gene, which regulates the sarcosine pathway, is reduced in the sigL mutant, indicating that sigL affects the cell population by regulating the sox encoding sarcosine oxidase Sarcosine utilization.