RiboSyn is a New Method for Measuring Specific Growth Rates of Distinct Microbial Populations in Natural Systems

Measurements of microbial activities are important in understanding the cycling and transformations of organic and chemical compounds in aquatic and terrestrial environments. As such, a number of molecular biology based methods have been developed to measure microbial diversity, community activities and microbial transformations in cultured and mixed-populations. Although these techniques provide valuable information about the community composition and nutrient uptake, there are currently no methods that directly measure specific growth rates of distinct microbial populations in environmental samples. Recently, RiboSyn was developed to measure the specific growth rates of distinct microbial populations by determining the specific rate of ribosome synthesis. In this technique, cells are exposed to chloramphenicol, inhibiting the processing of pre16S rRNA to 16S rRNA. Using reverse transcription and primer extension, the ratio of pre16S rRNA to 16S rRNA can be measured and ribosome doubling time determined. Due to RT-RiboSyn's ability to target specific nucleotide sequences, the specific growth rate of distinct microbial populations in mixed cultures can be determined. In order to characterize community structure and function of specific bacterial populations in mixed natural assemblages, the RiboSyn method can be used parallel with fluorescent in situ hybridization (FISH), to identify and measure growth rates of individual populations of bacteria. In this proceeding, we will describe our research objectives which will be presented at the EWRI conference. The ability to measure specific growth rates of distinct microbial populations in a sample from a natural system would provide greater understanding of the microbial processes responsible for the utilization or transformation of chemical contaminants in the environment.