添加肉类蛋白对米酒乳杆菌生境适应相关基因表达的影响

Effects of Meat Protein Environments on Niche-specific Genetic Expression of Lactobacillus sakei

摘要:

米酒乳杆菌是常见的异型发酵乳酸菌，它常常用作肉类工业发酵剂。为了了解其在肉类环境中的生存状况，本文用定量PCR对米酒乳杆菌La22在添加肌浆蛋白和肌原纤维蛋白的培养基中生长时生境适应相关基因表达量进行分析。结果显示，在两种培养基中生长时，pH值均随时间的延长而下降，在添加肌浆蛋白的培养基略高于添加肌原纤维蛋白培养基。与对照相比，在添加肌浆蛋白培养基中的arcA、arcB、arcC、arcT以及添加肌原纤维蛋白培养基中的arcR基因表达量明显上调，其余几个arc基因也均上调，但不明显；压力相关基因lsa00513、usp4以及usp2在肌浆蛋白培养基中均明显上调；有6个ABC转运子基因在添加两种肌肉蛋白的培养基中表达量明显上调。结果表明米酒乳杆菌能通过能量转换与基因表达调节来适应含肉类蛋白的培养环境。

Abstract:

Lactobacillus sakei is a ubiquitous heterofermentative lactic acid bacterium that is frequently used as a meat industrial starter culture. To investigate its adaptations to a meat protein environment, quantitative real-time polymerase chain reaction (qRT-PCR) was used to analyze the niche-specific genetic expression of L. sakei strain La22 when cultured in myofibrillar and sarcoplasmic protein-supplemented chemically defined media (CDM). The results showed that pH decreased with time, and that the pH value in CDM containing myofibrillar proteins was higher than that in CDM with sarcoplasmic proteins. Genetic expressions of arcA, arcB, arcC, and arcT in CDM containing myofibrillar proteins and arcR in CDM containing sarcoplasmic proteins were significantly higher compared to the control. The remaining arc operon genes were also upregulated in both culture media, but the increases were not significant. Stress response genes lsa00513, usp4, and usp2 in CDM containing myofibrillar proteins were significantly upregulated, and six genes encoding ABC transporter were significantly upregulated in both protein media. The results suggested that L. sakei had adapted to a meat protein environment by energy conversion and modulation of genetic expression.