在变化的环境中进行细菌培养，有时会积累突变率增大的“转座子”品系，可能会增强它们进行适应性演化的潜力。这种情况经常发生在临床条件下。如果“转座子”要长久存在，它们就需要一个一致变化的环境。与寄生体(如病毒)共同演化是能够提供这种环境的一个情形。现在，用假单胞菌所作的实验表明，与一种自然出现的噬菌体共同演化会明显提高细菌突变率，导致噬菌体绝灭概率增高。因此，以噬菌体种群为控制目标可能是在临床感染环境中削弱对“转座子”选择性的一种办法。
原始出处:
Nature 450, 1079-1081 (13 December 2007) | doi:10.1038/nature06350; Received 9 July 2007; Accepted 4 October 2007; Published online 2 December 2007
Coevolution with viruses drives the evolution of bacterial mutation rates
Csaba Pal1,2, María D. Maciá3, Antonio Oliver3, Ira Schachar1 & Angus Buckling1
Department of Zoology, University of Oxford, Oxford OX1 3PS, UK
Institute of Biochemistry, Biological Research Center, Temesvári krt. 62. Szeged, H-6701, Hungary
Servicio de Microbiologia and Unidad de Investigación, Hospital Son Dureta, Instituto Universitario de Investigación en Ciencias de la Salud (IUNICS), 07014, Palma de Mallorca, Spain
Correspondence to: Csaba Pal1,2Angus Buckling1 Correspondence and requests for materials should be addressed to A.B. (Email: angus.buckling@zoo.ox.ac.uk) or C.P. (Email: cpal@ramet.elte.hu).
Abstract
Bacteria with greatly elevated mutation rates (mutators) are frequently found in natural1, 2, 3 and laboratory4, 5 populations, and are often associated with clinical infections6, 7. Although mutators may increase adaptability to novel environmental conditions, they are also prone to the accumulation of deleterious mutations. The long-term maintenance of high bacterial mutation rates is therefore likely to be driven by rapidly changing selection pressures8, 9, 10, 11, 12, 13, 14, in addition to the possible slow transition rate by point mutation from mutators to non-mutators15. One of the most likely causes of rapidly changing selection pressures is antagonistic coevolution with parasites16, 17. Here we show whether coevolution with viral parasites could drive the evolution of bacterial mutation rates in laboratory populations of the bacterium Pseudomonas fluorescens 18. After fewer than 200 bacterial generations, 25% of the populations coevolving with phages had evolved 10- to 100-fold increases in mutation rates owing to mutations in mismatch-repair genes; no populations evolving in the absence of phages showed any significant change in mutation rate. Furthermore, mutator populations had a higher probability of driving their phage populations extinct, strongly suggesting that mutators have an advantage against phages in the coevolutionary arms race. Given their ubiquity, bacteriophages may play an important role in the evolution of bacterial mutation rates.
