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。%σ54 encoded by sigL plays a very important role to regulate many metabolic pathways in bacteria. To determine the function of sigL gene of Bacillus thuringiensis HD-73 strain, the utilization of different carbon and nitrogen sources in Bacillus thuringiensis HD-73 wild-type and sigL mutant stains were analyzed in this study. The results showed that both wild-type strain and sigL mutant could not use fructose, sucrose, cellobiose and citric-acid as the sole carbon source. sigL mutant could not use sarcosine, leucine, isoleucine, serine and valine as the sole nitrogen source. It indicated that the deletion of sigL gene might block the metabolic pathway which contained these amino acids.β-galacto-sidase assay showed that the transcriptional activation of soxR gene which encoded σ54 dependent transcription activator was decreased in sigL mutant. It indicated that the sarcosine metabolic pathway was regulated byσ54 by way of the transcription activator SoxR.
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