Brockhurst Michael A, Fenton Andrew, Roulston Barrie, Rainey Paul B
Department of Plant Sciences, University of Oxford, Oxford, OX1 3RB, UK.
BMC Ecol. 2006 Dec 13;6:19. doi: 10.1186/1472-6785-6-19.
Phages are thought to play a crucial role in the maintenance of diversity in natural bacterial communities. Theory suggests that phages impose density dependent regulation on bacterial populations, preventing competitive dominants from excluding less competitive species. To test this, we constructed experimental communities containing two bacterial species (Pseudomonas fluorescens and Pseudomonas aeruginosa) and their phage parasites. Communities were propagated at two environmental temperatures that reversed the outcome of competition in the absence of phage.
The evenness of coexistence was enhanced in the presence of a phage infecting the superior competitor and in the presence of phage infecting both competitors. This occurred because phage altered the balance of competitive interactions through reductions in density of the superior competitor, allowing concomitant increases in density of the weaker competitor. However, even coexistence was not equally stable at the two environmental temperatures.
Phage can alter competitive interactions between bacterial species in a way that is consistent with the maintenance of coexistence. However, the stability of coexistence is likely to depend upon the nature of the constituent bacteria-bacteriophage interactions and environmental conditions.
噬菌体被认为在维持自然细菌群落的多样性方面起着关键作用。理论表明，噬菌体对细菌种群施加密度依赖性调控，防止竞争优势种排除竞争力较弱的物种。为了验证这一点，我们构建了包含两种细菌（荧光假单胞菌和铜绿假单胞菌）及其噬菌体寄生物的实验群落。群落在两个环境温度下进行繁殖，这两个温度逆转了在没有噬菌体情况下的竞争结果。
在存在感染优势竞争者的噬菌体以及存在感染两种竞争者的噬菌体的情况下，共存的均匀度得到提高。这是因为噬菌体通过降低优势竞争者的密度改变了竞争相互作用的平衡，使得较弱竞争者的密度随之增加。然而，在这两个环境温度下，均匀共存并非同样稳定。
噬菌体能够以与维持共存相一致的方式改变细菌物种之间的竞争相互作用。然而，共存的稳定性可能取决于组成细菌 - 噬菌体相互作用的性质以及环境条件。
