Key Laboratory of Special Pathogens and Biosafety, Wuhan Institute of Virology, Center for Biosafety Mega-Science, Chinese Academy of Sciences, Wuhan 430071, China.
University of Chinese Academy of Sciences, Beijing 100049, China.
Viruses. 2020 Apr 9;12(4):423. doi: 10.3390/v12040423.
Phage stability is important for the successful application of bacteriophages as alternative antibacterial agents. Considering that temperature is a critical factor in phage stability, this study aimed to explore the possibility of improving long-term phage stability through adaptive evolution to elevated temperature. Evolution of three wild-type ancestral phages ( phage Wc4 and phages CX5 and P-PSG-11) was induced by subjecting the phages to heat treatment at 60 °C for five cycles. The adapted phages showed better stability than the wild-type ancestral phages when subjected to heat treatment at 60 °C for 1 h and after 60 days of storage at 37 °C. However, the adapted phages could not withstand thermal treatment at 70 °C for 1 h. The infectivity and the lytic properties of the phages were not changed by the evolution process. Whole-genome sequencing revealed that single substitutions in the tail tubular proteins were the only changes observed in the genomes of the adapted phages. This study demonstrates that adaptive evolution could be used as a general method for enhancing the thermal stability of phages without affecting their lytic activity. Sequencing results showed that bacteriophages may exist as a population with minor heterogeneous mutants, which might be important to understand the ecology of phages in different environments.
噬菌体稳定性对于将噬菌体作为替代抗菌剂成功应用非常重要。鉴于温度是影响噬菌体稳定性的关键因素，本研究旨在通过适应高温来探索提高噬菌体长期稳定性的可能性。通过将噬菌体在 60°C 下热处理 5 个循环，诱导三种野生型始祖噬菌体（噬菌体 Wc4 和噬菌体 CX5 和 P-PSG-11）发生适应性进化。与野生型始祖噬菌体相比，经过适应性进化的噬菌体在 60°C 下热处理 1 小时和在 37°C 下储存 60 天后表现出更好的稳定性。然而，适应性噬菌体不能承受 70°C 下 1 小时的热处理。噬菌体的感染性和裂解特性在进化过程中没有发生变化。全基因组测序显示，适应噬菌体基因组中唯一观察到的变化是尾部管状蛋白的单个取代。本研究表明，适应性进化可以作为一种通用方法来提高噬菌体的热稳定性，而不影响其裂解活性。测序结果表明，噬菌体可能作为具有微小异质突变体的群体存在，这对于理解噬菌体在不同环境中的生态可能很重要。
