Characterization and genomic analysis of two novel Eubacteriaceae bacterial strains ES2 & ES3

Abstract

An anaerobic, mesophilic, chemolithoautotrophic, and acetogenic bacterial strains ES2 and ES3 were isolated from sediment of Eulsukdo, a delta island in South Korea. Both strains clustered in coherent branch and were phylogenetically located between the genera Acetobacterium and Eubacterium. Considering phylogenetic distance over 16S rRNA and ANI values with neighboring genera, ES strains appear to be novel at the genus level. The genome size of the strains ES2 and ES3 was 3.76 Mbp and 3.39 Mbp, respectively and the DNA G+C contents of two strains ranged 39.6-40.7 mol%. Genomic evidence for the Wood-Ljungdahl pathway in ES strains reflects chemolithoautotrophic growth. Both strains could grow with CO2/H2 or CO as the sole sources of carbon and energy. ES2 expected to utilize methanol as an intermediate of WLP via genomic analysis and it was proved by batch culture. In addition, the genome of the strain contained a group of genes involved in lactic acid, 1-propanol, 2,3-BDO, and ethanol metabolism. A comparative genome analysis of ES strains with Acetobacterium woodii and Eubacterium limosum was conducted on key clusters of WLP. Synteny analysis revealed that genome arrangement of two novel strains were close to Acetobacterium woodii than Eubacterium limosum. In this study we aim to isolate industrially valuable acetogen strains from the marine environment. As a result we isolated ES strains and identified the genomic and the metabolic characteristics.