Marine Biotechnology Fellowship: Ribosomal RNA Regulation in Marine Bacteria

海洋细菌是海洋生产力的重要环节， 地球化学循环 虽然海洋生物的种类组成 细菌在很大程度上是未知的，有证据表明，大多数海洋细菌， 细菌是紫细菌门的成员， 真细菌界 该门包含光合作用， 异养细菌和石养细菌。 许多成员都有能力 氮和硫的氧化或还原， 在海洋环境中极为重要。 这个项目 试图确定RNA/DNA比率之间的一般关系 和紫色细菌的生长速度。 的新证据 海洋紫色细菌，海洋假单胞菌，表明 RNA/DNA比率和生长速度之间的关系 海洋中的低增长率。 此外，PS。perfectomarina数据与 在接近最大生长时对肠细菌测量的RNA/DNA比 rates. 然而，这一点尚未得到广泛证实， RNA/DNA比值与生长速率之间的预测关系是 对其他紫色细菌在整个生长范围内有效 自然环境中可能存在的速率。 为了 扩大rRNA探针的库，可用于测量 微生物在海洋中的生长速度，一个五步的方法将是 （1）克隆海洋rRNA基因， rRNA启动子-报告基因融合，以评估是否存在 以增长率依赖的方式进行调控; 2）经验上 测量六种海洋细菌的RNA-DNA比率与生长率 （代表紫色细菌的三个细分）使用 以前建立的方法; 3）研究机制 控制海洋细菌中rRNA的合成; 4）筛选 海洋细菌的基因组中是否存在新基因 5）23 SrRNA的克隆和测序 每种海洋细菌亚基，并鉴定种特异性 将用于测定原位生长速率的区域， 南加州湾的海水样本 如果一般 发现RNA/DNA比率与生长速率之间的关系， 研究人员可以常规地 确定是否存在并测量大型 自然样品中紫色细菌的数量。总之， 这对将来在海洋中使用rRNA探针非常重要， 研究rRNA与生长速率之间的关系。 没有其他大分子可以提供遗传和代谢 评估单一增长率所需的信息 微生物物种在一个复杂的组合没有风险 污染。

Marine bacteria are essential links in marine productivity and biogeochemical cycles. Although the species composition of marine bacteria is largely unknown, evidence suggests that most marine bacteria are members of the Purple bacteria phylum of the Eubacterial kingdom. The phylum contains photosynthetic, heterotrophic, and lithotrophic bacteria. Many members are capable of either the oxidation or reduction of nitrogen and sulfur which are extremely important in the marine environment. This project seeks to ascertain if a general relationship between RNA/DNA ratios and growth rate exists for the Purple bacteria. New evidence from the marine Purple bacterium, Pseudomonas perfectomarina, indicates that the relationship between RNA/DNA ratio and growth rate extends to the low growth rates believed to occur in the ocean. Furthermore, the Ps. perfectomarina data is in agreement with the RNA/DNA ratios measured on enteric bacteria at near maximal growth rates. However, it has not been widely established that this predictive relationship between RNA/DNA ratio and growth rate is valid for other Purple bacteria over the complete range of growth rates that can exist in the natural environment. In order to expand the repertoire of rRNA probes that can be used to measure microbial growth rate in the ocean, a five-step approach will be undertaken to: 1) clone the marine rRNA genes and create marine rRNA promoter-reporter gene fusions to assess if there is regulation in a growth rate-dependent manner; 2) empirically measure the RNA-DNA ratio vs growth rate for six marine bacteria (representing three subdivisions of the Purple bacteria) using previously established methods; 3) investigate the mechanisms controlling rRNA synthesis in the marine bacteria; 4) screen the marine bacteria's genomes for the presence of novel genes regulating rRNA synthesis; 5) clone and sequence the 23 S rRNA subunit of each marine bacterium and identify species-specific regions which will be used to assay the in situ growth rate in seawater samples from the Southern California Bight. If a general relationship between RNA/DNA ratios and growth rates are found to exist for these purple bacteria, investigators could routinely determine the presence and measure the growth rates of large numbers of Purple bacteria in natural samples. In conclusion, it is extremely important for the future use of rRNA probes in the ocean that the relationship between rRNA and growth rate be investigated. No other macromolecule can provide the genetic and metabolic information necessary to evaluate the growth rate of a single species of micro-organism in a complex assemblage without the risk of contamination.