Kong Minsuk, Ryu Sangryeol
Department of Food and Animal Biotechnology, Department of Agricultural Biotechnology, Research Institute of Agriculture and Life Sciences, and Center for Food and Bioconvergence, Seoul National University, Seoul, South Korea.
Department of Food and Animal Biotechnology, Department of Agricultural Biotechnology, Research Institute of Agriculture and Life Sciences, and Center for Food and Bioconvergence, Seoul National University, Seoul, South Korea
Appl Environ Microbiol. 2015 Apr;81(7):2274-83. doi: 10.1128/AEM.03485-14. Epub 2015 Jan 16.
Bacillus cereus is an opportunistic human pathogen responsible for food poisoning and other, nongastrointestinal infections. Due to the emergence of multidrug-resistant B. cereus strains, the demand for alternative therapeutic options is increasing. To address these problems, we isolated and characterized a Siphoviridae virulent phage, PBC1, and its lytic enzymes. PBC1 showed a very narrow host range, infecting only 1 of 22 B. cereus strains. Phylogenetic analysis based on the major capsid protein revealed that PBC1 is more closely related to the Bacillus clarkii phage BCJA1c and phages of lactic acid bacteria than to the phages infecting B. cereus. Whole-genome comparison showed that the late-gene region, including the terminase gene, structural genes, and holin gene of PBC1, is similar to that from B. cereus temperate phage 250, whereas their endolysins are different. Compared to the extreme host specificity of PBC1, its endolysin, LysPBC1, showed a much broader lytic spectrum, albeit limited to the genus Bacillus. The catalytic domain of LysPBC1 when expressed alone also showed Bacillus-specific lytic activity, which was lower against the B. cereus group but higher against the Bacillus subtilis group than the full-length protein. Taken together, these results suggest that the virulent phage PBC1 is a useful component of a phage cocktail to control B. cereus, even with its exceptionally narrow host range, as it can kill a strain of B. cereus that is not killed by other phages, and that LysPBC1 is an alternative biocontrol agent against B. cereus.
蜡样芽孢杆菌是一种机会性人类病原体，可导致食物中毒和其他非胃肠道感染。由于多重耐药蜡样芽孢杆菌菌株的出现，对替代治疗方案的需求日益增加。为了解决这些问题，我们分离并鉴定了一种长尾噬菌体科烈性噬菌体PBC1及其裂解酶。PBC1显示出非常狭窄的宿主范围，仅感染22株蜡样芽孢杆菌菌株中的1株。基于主要衣壳蛋白的系统发育分析表明，PBC1与克拉克芽孢杆菌噬菌体BCJA1c和乳酸菌噬菌体的关系比与感染蜡样芽孢杆菌的噬菌体更为密切。全基因组比较表明，PBC1的晚期基因区域，包括末端酶基因、结构基因和穿孔素基因，与蜡样芽孢杆菌温和噬菌体250的相似，但其内溶素不同。与PBC1的极端宿主特异性相比，其内溶素LysPBC1显示出更广泛的裂解谱，尽管仅限于芽孢杆菌属。单独表达时，LysPBC1的催化结构域也显示出芽孢杆菌特异性裂解活性，对蜡样芽孢杆菌组的活性较低，但对枯草芽孢杆菌组的活性高于全长蛋白。综上所述，这些结果表明，烈性噬菌体PBC1即使宿主范围异常狭窄，也是控制蜡样芽孢杆菌的噬菌体鸡尾酒的有用成分，因为它可以杀死其他噬菌体无法杀死的一株蜡样芽孢杆菌，并且LysPBC1是一种针对蜡样芽孢杆菌的替代生物防治剂。
