Abramczuk, Victoria, Department of Biology, Bucknell University, 701 Moore Avenue C0004, Lewisburg, PA 17837, vma005@bucknell.edu; Stowe, Emily, Department of Biology, Bucknell University, Rooke Science, 1 Dent Drive, Lewisburg, PA 17837, estoweva@bucknell.edu.
The microbial community of a particular environment is essential for the maintenance of the biogeochemical cycles within that environment. Microbes can also help the maintain the health of the environment by breaking down pollutants (bioremediation). In 2021, while characterizing the microbial community of the pond at the Bucknell Natural area, we isolated an orange-pigmented bacteria called ME4. After sequencing the genome, we conducted 16S rRNA, ANI, and pangenome analysis to determine the taxonomy and genomic composition of ME4. We used BIOLOG GenIII plates to determine the carbon metabolism and growth characteristics of ME4. While ME4 has greater than 95% 16S rRNA gene identity with Paracoccus marcusii, further analysis revealed an ANI value <88% compared to all sequenced P. marcusii strains. This finding suggests ME4 is a unique species of Paracoccus. Results from the GENIII plate also indicate that ME4 can tolerate up to 4% NaCl. Salt tolerance in other bacteria is often regulated by the SigF osmolarity regulation pathway, which may also be connected to pigment production and oxidative stress resistance. To characterize the response of ME4 to stress, we used qPCR to assess transcriptional changes in SigF regulated genes (pknD, sigF, nrsF, crtY, TreY) after exposure to 4% NaCl solution and 10mmol/L peroxide solutions. These findings emphasize not only the breadth of unidentified microbes in our ecosystems, but the value of using whole-genome taxonomic analyses like ANI rather than 16S rRNA analyses to identify them. Additionally, as salt tolerant Paracoccus species have potential use in whey bioremediation, understanding the response of ME4 to osmotic stress will help us determine if ME4 could have similar applications.
microbial ecology, osmotic stress, bacteria, bioremediation