Potential Thermotolerant Lactobacilli Isolated from Chicken Gastrointestinal Tract for Probiotic Use in Poultry Feeds

Abstract

Introduction Probiotic microorganisms and organic acids maintain the beneficial effect as an alternative to the use of antibiotics in feeds1. A probiotic is a “live microbial feed supplement which beneficially affects the host animal by improving its intestinal microbial balance”2-3. Antibiotics have been supplemented to animal and poultry feed to improve growth performance and efficiency; protect animals from adverse effects of pathogenic and non-pathogenic enteric microorganisms4. There are also reports that antibiotics could increase the colonization of the chicken gut by salmonellae, creating a potential public health problem5. The feeding of antibiotics also resulted in the retention of antibiotics in animal tissue, imbalances in normal intestinal flora, reduced beneficial intestinal microbial populations, and the generation of antibiotic-resistant bacteria. To overcome these problems, efforts have been directed towards the development and use of probiotics in food animals6. Probiotic supplementation of the intestinal microflora in poultry, especially with Lactobacillus species, showed beneficial effects on resistance to infectious agents such as Escherichia coli7, Salmonella spp.8. The significant roles of probiotics activities are determined in improving digestive functions, as well in immune system against infectious diseases9. The natural intestinal flora is a protective barrier against pathogens that can also affect nutrient digestion and absorption. Commercial probiotics constitute single or multiple strains of beneficial bacteria. Among the potential probiotics, lactic acid bacteria (LAB) are reported to have important effects in animals10. In vivo studies investigating health benefits of potential probiotics are time-consuming and often expensive; hence, the consequent use of in vitro tests as selection criteria to reduce the number of strains and find the most effective organism is unavoidable. Antimicrobial effects are major characteristics in the selection of LAB as probiotic candidates because these attributes provide competitiveness against enteric pathogens and reduce their colonization11. Recent studies have focused on improving the probiotic efficacy and represent more applicable supplements in poultry nutrition. The aim of the research work was to identify thermotolerant lactobacilli strains isolated from gastrointestinal digestive tracts of broiler chiken and study their responses to the criteria’s selection probiotic in order to select strains to be used as probiotic in the poultry feed.