Int. J. Pharm. Sci. Rev. Res., 15(1), 2012; nᵒ 03, 10-14 ISSN 0976 – 044X International Journal of Pharmaceutical Sciences Review and Research Page 10 Available online at www.globalresearchonline.net Funmilola Abidemi AYENI and Bolanle ADENIYI Department of Pharmaceutical Microbiology, Faculty of Pharmacy, University of Ibadan, Ibadan. Nigeria. Accepted on: 15-05-2012; Finalized on: 30-06-2012. ABSTRACT Enterococcus faecalis FAA025 and Streptococcus equines FAA026 have been previously selected for their probiotic potentials for human application. This study was carried out to ascertain that the strains are safe for human consumption through screening for tranferable antibiotic resistant and biogenic amines genes. Antibiotic susceptibility pattern of the two bacterial strains were studied by broth microdilution. Polymerase Chain Reactions (PCR) of the isolates were tested to detect tetracycline and neomycin resistant genes. (tet W and aph 3-II). The presence of 3 biogenic amine genes (tyrosine decarboxylase, (tdc), histidine decarboxylase (hdc) and agmatine deimininase (AgDI) were screened in the 2 bacterial isolates by PCR reactions. The two bacterial strains were sensitive to most tested antibiotics. Tetracycline and neomycin resistant genes could not be detected in the two bacterial strains. The 3 biogenic amines genes were absent in Streptococcus equines FAA026 while tdc and AgDI genes were detected in Enterococcus faecalis FAA025. With reference to absence of antibiotic resistant genes and biogenic amines genes, Streptococcus equines FAA026 is safe for probiotic use while Enterococcus faecalis FAA025 has been screened out of further studies on its potential probiotic properties due to the presence of tdc and AgDI genes. Keywords: Probiotics, Genes, Polymerase Chain Reactions, Safety, bacteria. INTRODUCTION Enterococci and streptococci are members of Lactic Acid Bacteria (LAB). Both genera have similar properties. Enterococci were formerly classified with Streptococci as group D streptococci but, were later placed in a genus of their own in the 1980s. Enterococci and streptococci have a widespread presence in the environment and have been reported to produce antimicrobial substances inhibitory to spoilage organisms. 1 Moreover, enterococci and streptococci are used as probiotic organisms because of their good growth, adhesive ability, lactic acid production e.t.c. 2 Probiotics are “Live microorganisms which when administered in adequate amounts confer a health benefit on the host.” 3 Probiotic strains must be included into the GRAS (General Regarded as Safe) microorganisms that comprise the genera Lactobacillus, Pedicocci, Bifidobacteria and some Streptococcus strains (Also, other genera that have been proven to be safe can be included). Historical data must indicate that they are safe for human use, based on their occurrence as normal commensals of the human microbiota, and their safe use in different foods and products worldwide. Before using an organism as probiotics, the FAO and WHO guidelines recommend that the probiotic strains must be characterized in series of tests which includes absence of side effects during clinical trials, absence of toxins (including virulent biogenic amines genes) and absence of antibiotic resistance genes. 4 The probiotic strain must not harbour any virulent antibiotic resistant genes which can be easily transferred to human during consumption. Enterococci has been noted for its resistance to a variety of antimicrobials due to intrinsic or acquired resistance. 5 While intrinsic resistance may be desirable in probiotic strains especially for patients already on antibiotic chemotherapy, acquired resistance is undesirable. Biogenic amines (BA) are organic bases of low molecular mass that are formed and degraded during the normal metabolism of microorganisms, plants, and animals. They are necessary for several physiological functions in humans. However, they are toxic if high concentrations are ingested or if the detoxification process is inhibited (either genetically or by drugs). 6 Foods likely to contain high levels of BA include fishery products and fermented foods such as cheese, wine, beer, and cured sausages. 7 Biogenic amines form via the decarboxylation of their corresponding amino acids through the action of enzymes produced by microorganisms present in the food (e.g., Enterobacteriae, Pseudomonas spp., enterococci, and some LAB. 8 Nonetheless, production is more related to strain than species. Producer strains can appear as contaminants of fermented foods, but they can also form part of starter cultures. It is therefore useful to determine which strains produce undesirable compounds so that these are not part of starter cultures or LAB intended for probiotic use. Histamine and tyramine are the most studied of the BA because they have toxicological effects that derive from their vasoactive and psychoactive properties. These compounds are formed from histidine and tyrosine, respectively, via an enzymatic decarboxylation reaction. The histidine decarboxylase genes (hdc) of different Gram-positive bacterial strains have been characterized. 9 The biochemical properties of histidine decarboxylase from Lactobacillus have been SAFETY EVALUATION OF ENTEROCOCCUS FAECALIS FAA025 AND STREPTOCOCCUS EQUINES FAA026 FOR HUMAN PROBIOTIC APPLICATION. Research Article