Boot H J, Kolen C P, Pot B, Kersters K, Pouwels P H
BioCentrum Amsterdam, University of Amsterdam, The Netherlands.
Microbiology (Reading). 1996 Sep;142 ( Pt 9):2375-84. doi: 10.1099/00221287-142-9-2375.
Previously we have shown that the type strain of Lactobacillus acidophilus possesses two S-protein-encoding genes, one of which is silent, on a chromosomal segment of 6 kb. The S-protein-encoding gene in the expression site can be exchanged for the silent S-protein-encoding gene by inversion of this slp segment. In this study the presence of S-protein and corresponding S-protein-encoding genes of strains belonging to species that are closely related to L. acidophilus was determined. All strains investigated were identified by numerical comparison of highly standardized one-dimensional SDS-PAGE whole-cellular-protein patterns. Western blot and Southern blot methods were used to identify the presence of, and homology between, S-proteins and S-protein-encoding genes. From these analyses we conclude that strains of L. acidophilus, L. crispatus, L. amylovorus and L. gallinarum possess an S-layer and contain two slp genes. Strains of L. helveticus possess an S-layer but have only one intact slp gene. Strains of L. gasseri, L. johnsonii and L. delbrueckii subsp. bulgaricus have neither an S-layer nor S-protein-encoding genes hybridizing with probes derived from the L. acidophilus slpA or slpB region. The presence of a highly conserved 5' region in the slp genes of strains of L. acidophilus, L. crispatus, L. amylovorus and L. gallinarum suggests that S-layer variation is a common feature for strains of these species.
此前我们已经表明，嗜酸乳杆菌的模式菌株在一个6 kb的染色体片段上拥有两个编码S蛋白的基因，其中一个是沉默基因。通过该slp片段的倒位，表达位点上的编码S蛋白的基因可以与沉默的编码S蛋白的基因进行交换。在本研究中，我们测定了与嗜酸乳杆菌密切相关的物种的菌株中S蛋白和相应的编码S蛋白的基因的存在情况。所有研究的菌株均通过高度标准化的一维SDS-PAGE全细胞蛋白图谱的数值比较进行鉴定。采用蛋白质免疫印迹法和Southern印迹法来鉴定S蛋白和编码S蛋白的基因的存在情况以及它们之间的同源性。从这些分析中我们得出结论，嗜酸乳杆菌、卷曲乳杆菌、解淀粉乳杆菌和鸡乳杆菌的菌株具有S层并且含有两个slp基因。瑞士乳杆菌的菌株具有S层，但只有一个完整的slp基因。加氏乳杆菌、约氏乳杆菌和德氏乳杆菌保加利亚亚种的菌株既没有S层，也没有与源自嗜酸乳杆菌slpA或slpB区域的探针杂交的编码S蛋白的基因。嗜酸乳杆菌、卷曲乳杆菌、解淀粉乳杆菌和鸡乳杆菌的菌株的slp基因中高度保守的5'区域的存在表明，S层变异是这些物种菌株的一个共同特征。
