In Vitro Characterization of Indigenous Probiotic Strains Isolated from Colombian Creole Pigs

SIMPLE SUMMARY: In the pig industry (mainly after weaning), enteric diseases are frequent associated with pathogenic bacteria such as Salmonella spp. and E. coli. Although the European Union has banned the use of growth-promoting antibiotics, many countries use these synthetic medications with widespread, which has led to an increase in the number of antibiotic-resistant pathogens, cross-resistance, and bioaccumulation in tissues. Probiotics are beneficial bacteria that live in the intestine and improve the host health; they are also one of the main alternatives to subtherapeutic antibiotics. Therefore, our goal was to obtain lactic acid bacteria from Colombian creole pigs that had never consumed a medicated diet and to carry out in vitro probiotic tests. Three strains lived before were identified: L. plantarum CAM6, L. plantarum CAM7 and L. plantarum CL4. The obtained strains have good activity in the physiological, antibacterial and antibiogram tests. Further studies to evaluate the efficacy of this strain in commercial pigs are currently being evaluated. ABSTRACT: Three lactic acid strains were isolated from feces of the native Zungo Pelado breed of pigs (n = 5) and presumably identified as belonging to the Lactobacillaceae family by morphological techniques showing that they were Gram-positive/rod-shaped and catalase- and oxidase-negative. They were then identified by biochemical tests using API 50CHL as Lactobacillus plantarum (CAM6), Lactobacillus brevis (CAM7), and Lactobacillus acidophilus (CL4). However, 16S rRNA identification showed that all three strains were Lactobacillus plantarum. Additionally, all three isolates were able to grow in pH 3 and 4. Interestingly, the growth of the CAM7 strain decreased at pH 5.6 compared to that of the CAM6 strain (p < 0.05), and the growth of the CL4 strain was reduced at pH 7(p < 0.05). All three candidates showed good growth on bile salts (≥0.15%), and CAM6 and CAM7 showed better tolerance at higher concentrations (0.30%). Similarly, all strains tolerated sodium chloride (NaCl) concentrations from 2 to 10%. These strains also grew well at all temperatures tested (30, 37, and 42 °C). The CAM6 strain showed in vitro antibacterial activity against selected enteropathogenic bacteria (Escherichia coli strain NBRC 102203 and Salmonella enterica serovar Typhimurium 4.5.12) and commensal bacteria (Klebsiella pneumoniae ATCC BAA-1705D-5 and Pseudomonas aeruginosa ATCC 15442) and resistance to all antibiotics except amoxicillin. Further studies to evaluate the effects of these probiotic candidate strains in commercial pigs are currently underway.