Strains of Lactobacillus spp. with probiotic capacity isolated from the intestinal tract of calves

[摘要] Seventeen strains of Lactobacillus spp. isolated from the intestinal tract of neonatal calves were characterized in vitro to select the best ones as probiotic candidates and to study them in vivo. All the isolates were tested for catalase, Gram stained, and their cultural characteristics studied for their preliminary identification. Their probiotic capacity, such as growth at different temperatures (30, 37, and 45°C), pH (2.5, 3.4, 5.4, 6.4), and their capacity to acidify the culture medium, were assessed in vitro. Ten strains of Lactobacillus spp. growing under all the conditions tested were preselected, standing out growths of viable cells of 6,7-10 log CFU/ml that reduced pH values to 3.2-4.0. Then, their functional characteristics such as tolerance to artificial gastric juice and to bile salts (0.3% Oxgall), and their microbial antagonism activity against four pathogens of veterinary interest were evaluated. The result obtained showed probiotic potential in four of the Lactobacillus spp. strains tested for their resistance to treatment with bile salts until 24 hours and the microbial growth of 3.52-6.5 log CFU/ml with artificial gastric juice observed after 90 minutes; they also inhibited the growth of Salmonella sp., Staphylococcus aureus, Escherichia coli and Listeria monocytogenes. The profile of susceptibility to 13 antimicrobials was evaluated, and most of the strains revealed resistance to three of them.

[学科分类] 兽医学