Physiology and genetics of candidate probiotic strains relevant to animal health and production

Probiotic microorganism inclusion in feeds is emerging as a popular and potentially valuable tool in the practice of human and veterinary medicine and animal production. Recent research work has contributed to clarify the appropriate probiotic organisms, appropriate doses and conditions that are potentially treatable with probiotic strains in several farm animal species. The appealing properties of probiotics include the ability to reduce antibiotic use, the apparently very high index of safety, and the public’s perception about ‘natural’ or ‘alternative’ therapies. Probiotic organisms must survive the acidic environment of the stomach and resist to the digestion process, adhere to the intestinal lining, colonize the intestinal tract and produce beneficial factors and inhibit pathogens (disease-causing bacteria). Other properties such as immunomodulation and modulation of metabolic activities are also desirable. Probiotics must be identified at the strain level from faecal and intestinal samples by means of molecular tools (DGGE, Real-time PCR analysis) and testing must be performed on individual strains.