Microbial community assemblages have long been understood as key components within freshwater ecosystems. However, patterns of microbial presence and persistence along stream continuums, in relation to specific host organisms, have been understudied. The identification of such patterns may provide insight into the dynamics of microbial assemblages along stream continuums. One such pattern was observed in a recent lab-based experiment that involved crayfish with and without branchiobdellidan ectosymbionts (Cooke et al., 2017). Microbial 16S genes were isolated and sequenced, revealing that bacterial taxa present on specimens with symbionts were distinct from those without symbionts. This current study looks for a similar pattern by analyzing the microbial community assembly within the stream environment (water and sediment) and on crayfish in a local stream. It is hypothesized that patterns of microbial presence and persistence will change in relation to location along the stream continuum and in relation to the presence or absence of ectosymbionts. Bacterial samples from crayfish and the environment were collected using aseptic technique at five different collection sites along Opossum Creek in central Virginia. DNA was extracted using a Qiagen Blood and Tissue Kit and qPCR was performed for quantitative analysis of microbial composition and abundance.
Results/Conclusions
Initial qPCR results suggest that stream order, location and other environmental factors may have an effect on microbial abundance. Differences in microbial abundance were observed among all stream locations in the water, substrate, and crayfish microbiome samples. In the future, PCR will be used for microbial 16S gene amplification, in order to identify specific microbial taxa present in the samples. This process will yield a substantial amount of data; moreover, to sort through mixed PCR product, Illumina sequencing will be employed. The resulting data will be sorted and analyzed using the bioinformatics software, QIIME. By incorporating this data with the results from qPCR, both microbial diversity and abundance will be characterized along the length of the stream continuum, as well as in relation to a specific host organism.