Relative Contributions of Halobacteriovorax and Bacteriophage to Bacterial Cell Death under Various Environmental Conditions.
Relative Contributions of Halobacteriovorax and Bacteriophage to Bacterial Cell Death under Various Environmental Conditions.
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DOI：
10.1128/mbio.01202-18
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发表时间：
2018-08-07
期刊：
影响因子：
6.4
通讯作者：
Williams HN
中科院分区：
文献类型：
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作者：
Chen H;Laws EA;Martin JL;Berhane TK;Gulig PA;Williams HN
原生生物和噬菌体在微生物食物网中的细菌捕食作用已经得到了很好的研究。越来越多的证据表明，蛭弧菌和类似生物（BALO）也有助于细菌死亡率，在某些情况下，比噬菌体更重要。要充分了解微生物食物网的生态功能，就需要认识到所有主要的捕食者和每种捕食者的贡献的大小。在这里，我们调查的贡献Halobacteriovorax，BALO之一，和噬菌体孵育时，他们共同的猎物，创伤弧菌，在海水中的微观世界。我们观察到，嗜盐菌是最大的猎物，增加18倍，同时减少4.4对数单位的创伤弧菌在40小时，而噬菌体人口没有显着增加。在随后的实验中，制定一个介质，将支持捕食活动和复制的两个捕食者，低营养介质有利于捕食和复制的嗜盐菌，而较高的营养介质增强噬菌体生长。最大的猎物减少和复制Halobacteriovorax和噬菌体中观察到中等营养水平的媒体。进一步的实验表明，这两种捕食者的捕食活动受到环境条件的影响，特别是温度和盐度。这两种捕食者结合起来对创伤弧菌产生了更大的控制作用，这种协同作用可用于减少细菌种群的实际应用。这些发现表明，噬盐菌沿着噬菌体和原生生物，在细菌死亡率和营养物质循环这两个重要的生态功能中具有重要作用。虽然已经报道了很多关于海洋微生物食物网和微型捕食者的作用，特别是病毒和原生生物，蛭弧菌类捕食者的贡献在很大程度上被忽视，在理解食物网过程中造成了重大差距。一个完整的情况下，微生物食物网不能开发，直到所有主要的micropredators的作用和它们的贡献的细菌死亡率，微生物群落的结构，和营养物质的循环的幅度进行评估。在这里，我们展示了令人信服的证据，嗜盐菌，一种捕食性细菌，是细菌死亡的一个重要贡献者，在某些情况下，可能与病毒竞争细菌死亡率的代理人。这些结果推进了当前对微生物循环和自上而下控制细菌群落的理解。
The role of protists and bacteriophages in bacterial predation in the microbial food web has been well studied. There is mounting evidence that Bdellovibrio and like organisms (BALOs) also contribute to bacterial mortality and, in some cases, more so than bacteriophages. A full understanding of the ecologic function of the microbial food web requires recognition of all major predators and the magnitude of each predator’s contribution. Here we investigated the contribution of Halobacteriovorax, one of the BALOs, and bacteriophages when incubated with their common prey, Vibrio vulnificus, in a seawater microcosm. We observed that Halobacteriovorax was the greatest responder to the prey, increasing 18-fold with a simultaneous 4.4-log-unit reduction of V. vulnificus at 40 h, whereas the bacteriophage population showed no significant increase. In subsequent experiments to formulate a medium that would support the predatory activities and replication of both predators, low-nutrient media favored the predation and replication of the Halobacteriovorax, whereas higher-nutrient media enhanced phage growth. The greatest prey reduction and replication of both Halobacteriovorax and phage were observed in media with moderate nutrient levels. Additional experiments show that the predatory activities of both predators were influenced by environmental conditions, specifically, temperature and salinity. The two predators combined exerted greater control on V. vulnificus, a synergism that may be exploited for practical applications to reduce bacterial populations. These findings suggest that along with bacteriophage and protists, Halobacteriovorax has the potential to have a prominent role in bacterial mortality and cycling of nutrients, two vital ecologic functions. Although much has been reported about the marine microbial food web and the role of micropredators, specifically viruses and protists, the contribution of Bdellovibrio-like predators has largely been ignored, posing a major gap in understanding food web processes. A complete scenario of the microbial food web cannot be developed until the roles of all major micropredators and the magnitude of their contributions to bacterial mortality, structuring of microbial communities, and cycling of nutrients are assessed. Here we show compelling evidence that Halobacteriovorax, a predatory bacterium, is a significant contributor to bacterial death and, in some cases, may rival viruses as agents of bacterial mortality. These results advance current understanding of the microbial loop and top-down control on the bacterial community.