In vitro probiotic selection and characterization of Lactobacillus spp. isolated from healthy domesticated Turkeys

Abstract

The health of poultry is closely related to how the animals are raised, and the gut microbiota plays a key role in the fulfillment of their productive potential. Lactobacillus spp. are bacteria present in the natural microbiota of poultry that, when employed as probiotic agents, should present several characteristics. This study aims at performing the in vitro probiotic isolation and characterization of Lactobacillus spp. Isolates were obtained from ceca content of healthy turkeys through the isolation and identification of morphological, molecular, and physiologic characteristics. They were identified through Gram staining, catalase and hydrogen peroxide production tests, gas production tests during glucose fermentation, and hydrogen sulfide production during the triple sugar iron test. The samples were identified molecularly through polymerase chain reaction tests and were subjected to genetic sequencing. The assessment of the probiotic potential was conducted through artificial gastric juice tolerance and bile salt tolerance tests. A hydrophobicity test was used as an indirect method of assessing an isolate's probable ability to adhere to the intestinal mucosa. In addition, other analyses were performed, such as multiplication potential tests, Salmonella Heildelberg antagonism assays, hydrogen peroxide production tests, and antibiograms, as well as an assessment of the genes responsible for resistance to antimicrobial agents in Integron C. In conclusion, we identified, through morphologic, physiologic, pathogen antagonism, and antimicrobial resistance tests, 11 strains of Lactobacillus spp. belonging to species L. reuteri (9), L. johnsonii (1), and L. frumenti (1) that showed potential as probiotic candidates for in vivo application.