COMPARATIVE GENOMIC ANALYSIS AMONG Enterococcus mundtii STRAINS ISOLATED FROM DIFFERENT SOURCES

BONACINA, JULIETA; HORMIGO, RICARDO; SUÁREZ, NADIA; SESMA, FERNANDO; SAAVEDRA, LUCILA

Mar del Plata

Congreso; X Congreso de Microbiología General; 2014

Sociedad Argentina de Microbiología General

Enterococci are a diverse and versatile group of gram positive lactic acid bacteria. They live as commensal microorganisms in the gastrointestinal tract of humans and animals, but they are also found in soil, water, plants and are used in the production of fermented foods and probiotics. Due to their intrinsic characteristics and a remarkable metabolic adaptability, they are capable of surviving and growing under different conditions and to tolerate many forms of stress. The study of enterococci´s genomics has grown considerably in recent years and has allowed us to obtain new insights into the physiology of this genus. Using different approaches it has been concluded that many metabolic genes and pathways vary, even within single species of this genus. Particularly, genome comparisons are really important for determining the genotypic differences between closely related bacteria and for understanding genomic and molecular evolution while considering the phenotypic evolution and population genetics. Enterococcus mundtii CRL35 is a bacteriocinogenic non starter lactic acid bacteria strain whose genome was recently sequenced. Based on this information, the goal of the present work was to perform a comparison of the metabolic reconstruction of this strain against those belonging to E. mundtii CRL1656 (cow milk isolate), E. mundtii QU 25 (ovine faecal origin) and E. mundtii ATCC 882 (fermented product origin), through the RAST tool. The results obtained revealed that QU 25 has, at the chromosome level, 67 coding DNA sequences (CDS) assigned to subsystems that are not present in CRL35. Some of these genes are involved in gram positive competence, CRISPR-Cas system, citrate metabolism and toxin antitoxin replicon stabilization systems. On the other hand, CRL35 has CDS related to bacterial restriction-modification system, sialic acid metabolism and biotin biosynthesis, that are not present in QU 25. Regarding CRL1656, 42 functional roles have genes assigned to subsystems that are not found in CRL35, some of which are related to the citrate metabolism and the com system. Also CRL35 has 46 roles with genes not localized in CRL1656. Finally, the strain ATCC 882 has 60 functional roles with genes involved in citrate metabolism, com system and phages production, that are not present in CRL35. Only 13 roles with genes assigned are found in CRL35 and not in ATCC 882. Furthermore, an orthology analysis evidenced that E. mundtii CRL35, CRL1656 and ATCC 882 have 1772 orthologous proteins while the last two strains have 2141 suggesting, therefore, a less evolutionary distance among them. These analyses help us to understand how enterococci adjust to different environments. Transcriptomic studies of CRL35, now under way, will provide an overview of the physiological responses of this microorganism in fermented foods.