Science et Technologie du Lait et de l'Œuf, CIRM-BIA, Rennes, France.
Int J Food Microbiol. 2011 Jul 15;148(1):1-7. doi: 10.1016/j.ijfoodmicro.2011.04.015. Epub 2011 Apr 21.
Peptidoglycan hydrolases (PGHs) are bacterial enzymes that can hydrolyze the peptidoglycan in bacterial cell wall leading to autolysis. By releasing intracellular enzymes, autolysis of Lactobacillus helveticus has important applications in cheese ripening as its extent varied from strain to strain. Nine genes coding PGHs were previously annotated in the genome of the high autolytic strain L. helveticus DPC 4571. This study was conducted to evaluate the clone diversity of the nine PGHs genes within a collection of 24 L. helveticus strains, highly diverse in terms of origin, biotope and autolytic activity. Pulsed field gel electrophoresis was applied to assess the genomic diversity of the 24 strains. The presence or absence of nine PGHs genes was verified for all L. helveticus strains. Nucleotide and deduced amino acid sequence were compared for six relevant strains. Finally, gene expression was monitored by reverse transcription during growth and by zymogram for 12 strains. The nine PGHs genes are ubiquitous and transcripted early during growth. Zymograms were similar in terms of molecular size of the bands, but exhibited strain to strain variations in the number of bands revealing from 2 to 5 lytic bands per strain.
肽聚糖水解酶（PGHs）是一种细菌酶，可以水解细菌细胞壁中的肽聚糖，导致自溶。通过释放细胞内酶，瑞士乳杆菌的自溶在奶酪成熟中具有重要的应用，因为其程度因菌株而异。先前在高自溶瑞士乳杆菌 DPC 4571 的基因组中注释了 9 个编码 PGHs 的基因。本研究旨在评估 24 株瑞士乳杆菌菌株中 9 个 PGHs 基因的克隆多样性，这些菌株在起源、生境和自溶活性方面高度多样化。应用脉冲场凝胶电泳评估 24 株菌株的基因组多样性。验证了所有瑞士乳杆菌菌株中 9 个 PGHs 基因的存在或缺失。对 6 株相关菌株的核苷酸和推导的氨基酸序列进行了比较。最后，通过反转录监测 12 株菌在生长过程中的基因表达，并通过酶谱监测 12 株菌的基因表达。这 9 个 PGHs 基因是普遍存在的，并且在生长早期转录。酶谱在条带的分子大小方面相似，但在带的数量上存在菌株间的差异，每个菌株显示 2 到 5 个溶菌带。
