Parmar Krupa M, Dafale Nishant A, Tikariha Hitesh, Purohit Hemant J
Environmental Biotechnology and Genomics Division, CSIR-National Environmental Engineering Research Institute, Nagpur, 440020, India.
Arch Microbiol. 2018 May;200(4):611-622. doi: 10.1007/s00203-017-1471-1. Epub 2018 Jan 12.
Combating bacterial pathogens has become a global concern especially when the antibiotics and chemical agents are failing to control the spread due to its resistance. Bacteriophages act as a safe biocontrol agent by selectively lysing the bacterial pathogens without affecting the natural beneficial microflora. The present study describes the screening of prominent enteric pathogens NDK1, NDK2, NDK3, and NDK4 (Escherichia, Klebsiella, Enterobacter, and Serratia) mostly observed in domestic wastewater; against which KNP1, KNP2, KNP3, and KNP4 phages were isolated. To analyze their potential role in eradicating enteric pathogens and toxicity issue, these bacteriophages were sequenced using next-generation sequencing and characterized based on its genomic content. The isolated bacteriophages were homologous to Escherichia phage (KNP1), Klebsiella phage (KNP2), Enterobacter phage (KNP3), Serratia phage (KNP4), and belonged to Myoviridae family of Caudovirales except for the unclassified KNP4 phage. Draft genome analysis revealed the presence of lytic enzymes such as holing and lysozyme in KNP1 phage, endolysin in KNP2 phage, and endopeptidase with holin in KNP3 phage. The absence of any lysogenic and virulent genes makes this bacteriophage suitable candidate for preparation of phage cocktail to combat the pathogens present in wastewater. However, KNP4 contained a virulent gene rendering it unsuitable to be used as a biocontrol agent. These findings make the phages (KNP1-KNP3) as a promising alternative for the biocontrol of pathogens in wastewater which is the main culprit to spread these dominated pathogens in different natural water bodies. This study also necessitates for genomic screening of bacteriophages for lysogenic and virulence genes prior to its use as a biocontrol agent.
对抗细菌病原体已成为全球关注的问题，尤其是当抗生素和化学药剂由于细菌的耐药性而无法控制其传播时。噬菌体通过选择性地裂解细菌病原体而不影响天然有益微生物群，从而作为一种安全的生物控制剂。本研究描述了对国内废水中最常见的主要肠道病原体NDK1、NDK2、NDK3和NDK4（大肠杆菌、克雷伯菌、肠杆菌和沙雷氏菌）的筛选；针对这些病原体，分离出了KNP1、KNP2、KNP3和KNP4噬菌体。为了分析它们在根除肠道病原体和毒性问题方面的潜在作用，使用下一代测序对这些噬菌体进行测序，并根据其基因组内容进行表征。分离出的噬菌体与大肠杆菌噬菌体（KNP1）、克雷伯菌噬菌体（KNP2）、肠杆菌噬菌体（KNP3）、沙雷氏菌噬菌体（KNP4）同源，除了未分类的KNP4噬菌体外，均属于有尾噬菌体目肌尾噬菌体科。基因组草图分析显示，KNP1噬菌体中存在诸如穿孔素和溶菌酶等裂解酶，KNP2噬菌体中存在内溶素，KNP3噬菌体中存在带有穿孔素的内肽酶。不存在任何溶原性和毒性基因使得这种噬菌体成为制备噬菌体鸡尾酒以对抗废水中存在的病原体的合适候选物。然而，KNP4含有一个毒性基因，使其不适合用作生物控制剂。这些发现使噬菌体（KNP1-KNP3）成为废水病原体生物控制的有前途的替代物，废水是这些主要病原体在不同天然水体中传播的主要罪魁祸首。本研究还需要在将噬菌体用作生物控制剂之前对其溶原性和毒力基因进行基因组筛选。
