GENOME-BASED CHARACTERIZATION OF STRAIN ENTEROCCUS FAECIUM ICIS21 FROM NATURALLY FERMENTED DAIRY PRODUCT

Abstract

Enterococcus faecium ICIS21 is a facultative anaerobic, gram-positive strain that is important in the food industry. This isolate was selected from a naturally fermented dairy product obtained in the Orenburg region, Russian Federation. Currently, there is increasing evidence supporting the important role of enterococci in human health and their use as a natural method for food preservation. This paper reports a draft genome sequence of E. faecium ICIS21, where we studied the strain genome using whole-genome sequencing, assembly, annotation, and subsequent bioinformatic analysis. We characterized its probiotic potential, including the production of bacteriocins (enterocin SE-K4, enterocin A, and enterolysin A), secondary metabolites (cyclic lactone autoinducer and T3pks), vitamins, and genes involved in unsaturated fatty acid biosynthesis.  Additionally, an important feature is the presence of a heavy metal resistance gene cluster, determining factors with various mechanisms for binding and removing a complex of heavy metals such as Hg, Co, Zn, Cd, Cu, Mg, Mn, Fe, and Ni. This may be significant for using the strain as a biosorbent for heavy metal ions. The presence of major virulence genes was not detected. The analysis showed the absence of transmissible antibiotic resistance genes (vanA, vanB, ermB, tetM, and aac(6′)-le-aph(2″)-la) and plasmids. The study results will be significant for further analysis of specific elements of the genome of this species and also open up prospects for developing microbial compositions with specified properties to expand the range of functional food products.