The Paradox of the Viroplankton: High Viral Abundance and Resistance to Infection

9811319保罗病毒是浮游生物中数量最多的组成部分，通常比原核和真核生物中的病毒多十倍。在大多数水生系统中，细菌和病毒之间存在稳定状态，而不会导致细菌或蓝藻宿主种群的崩溃。由于浮游生物的传染性在表面沃茨中衰减得相对较快，因此新的浮游生物必定会以同样快的速度重新供应。然而，蓝细菌（可能还有异养细菌）在很大程度上对噬菌体感染有抵抗力。在存在抗性宿主群体的情况下，噬菌体如何能够持续产生？在这个项目中检验的假设是，细菌群落在高病毒丰度的存在下持续存在，因为裂解性细菌选择了一个对感染有抵抗力的群落。另外，浮游细菌（包括蓝藻）坚持在高病毒丰度的存在，因为同源免疫赋予溶原性和假溶原性。 为了验证这些假设，该项目将朝着以下目标努力：1。使用培养物中的分离株确定溶解性、假溶原性和溶原性存在模式之间的关系。2.确定溶原性和溶解性存在之间的转变是否发生在天然微生物种群中，例如发生在坦帕湾的微生物种群。 3.确定海洋聚球藻分离株溶原性的流行情况。我们将研究一系列藻红蛋白含有和非PE含有菌株从文化收藏，以及我们自己的分离物从墨西哥湾的原噬菌体的存在下，丝裂霉素C和/或UVC曝光，并将使用这些菌株来了解溶原过程中的蓝藻。4.确定溶原性或假溶原性是聚球藻自然种群的耐药机制。 从这项研究中获得的结果可能会大大改变我们对微生物环中病毒的理解，从永久攻击宿主的裂解实体到高度进化的共生体中的共同参与者，这种共生体可能会根据环境线索从毒力转变为温和存在。

9811319PaulViruses are the most numerous component of the plankton, often ten-fold more abundant than their procaryotic and eucaryotic counterparts. In most aquatic systems, a steady state exists between bacteria and viruses without collapse of the bacterial or cyanobacterial host populations. Because the infectivity of phages decays relatively quickly in surface waters, there must be an equally rapid re--supply of new phages. However, the cyanobacteria (and perhaps the heterotrophic bacteria) are largely resistant to phage infection. How can there be constant phage production in the presence of a resistant host population? The hypothesis tested in this project is that bacterioplanlkon persist in the presence of high viral abundance because lytic phages have selected for a community that is resistant to infection. Alternatively, bacterioplankton (including cyanobacteria) persist in the presence of high viral abundance because of homo-immunity conferred by lysogeny and pseudolysogeny. To test these hypotheses, the project will work toward the following objectives: 1. To determine the relationship between lytic, pseudolysogenic, and lysogenic modes of existence using isolates in culture. 2. To determine if the transition between lysogeny and lytic existence occurs in natural microbial populations such as those occurring in Tampa Bay. 3. To determine the prevalence of lysogeny amongst marine Synechococcus isolates. We will examine a series of phycoerythrin containing and non-PE containing strains from culture collections as well as our own isolates from the Gulf of Mexico for the presence of prophage by mitomycin C and/or UVC exposure, and will use these strains to understand the process of lysogeny in cyanobacteria. 4. To determine if lysogeny or pseudolysogeny is the mechanism of resistance in natural Populations of Synechococcus. The results obtained from this study may substantially alter our understanding of viruses in the Microbial Loop, from lytic entities that perpetually attack their hosts to co-participants in a highly evolved symbiosis that may switch from virulence to temperate existence in response to environmental cues.