Biosafety assessment of lactic acid probiotic isolates obtained from the gastrointestinal tract of livestock, poultry and bees native to Iran

Abstract

Probiotics are suitable substitutes to reduce the use of growth-promoting antibiotics and antibiotics used to treat livestock infections due to new international laws and consumers' expectations of livestock products. Although lactic acid bacteria, especially Lactobacillus, are safe strains (GRAS¹), a safety study of new probiotic strains is needed to evaluate their safety and pathogenicity parameters. Such investigations can reduce concerns about antibiotic resistance genes transfer and observe rare cases of infection caused by probiotic usage. In the previous project of Iran Animal Biotechnology Research Institute, several lactic acid species were isolated and identified from the gastrointestinal tract of different farm animals via phenotypic characteristics and 16S rRNA sequencing. These bacteria had probiotic properties and were assessed for acid resistance, antibiotic resistance, bile salts, and antimicrobial activity. In this study, the presence or absence of several genes, such as pathogenic genes, amine-producing genes, and genes associated with antibiotic resistance, were examined by PCR.² Furthermore, genes that lead to the emergence of antibiotic resistance through other mechanisms such as efflux pumps were also studied in the same way. These studies have led to the achievement of safe strains for the introduction to the large market of livestock, poultry, and aquatic probiotics.