Nowroozi J. (Ph.D.), Mehdi Mirzaii, Kargar M. (Ph.D.), Razeghi R. (MSc).
Introduction: Lactobacilli are the most frequent bacteria in human’s gastrointestinal tract normal microflora and is found in sausage, dairy products and feces. The aim of this study was to isolate lactobacilli from sausage, dairy products and feces of children whose age were between 6 to 24 months and determine their inhibitory effect on enteric pathogens (E. coli, Salmonella, Shigella).
Methods: Different samples of sausage, dairy products and infant feces were collected and cultured on MRS medium. Lactobacilli were isolated and identified by standard methods (morphology, microscopic shape, fermentation of carbohydrates and biochemical tests). The growth of isolated bacteria at different temperature, pH and the inhibitory effect by spot on the lawn, blank disk and well diffusion on enteric pathogens (E. coli, Salmonella, Shigella), resistance to common antibiotics and bile of isolated bacteria were examined.
Results: From 150 samples, the isolated bacteria were Lacto. fermentum, Lacto. plantarum, Lacto. rhamnosus, Lacto. gasseri, Lacto. reuteri, Lacto. crispatus, Lacto. acidophilus.The inhibitory effect of substances from isolated lactobacilli from infant feces with breast – fed children were more stable than the other isolated from sausage and dairy products at low pH, high temperature, different concentration of bile salts
Discussion: Because of inhibitory effect, probiotic lactobacilli or their purified bacteriocin can use as biological preservative in sausage fermentation, dairy products. Our results showed that the number of lactobacilli in the feces of breast –fed children was predominant. It might be substances in breast milk that help the better growth of lactobacilli and by producing more inhibitory substances can change the entric pH that inhibit the growth and prevent the incidence of disease such as diarrhea. So, breast – fed is recommended, and they might be considered as probiotic bacteria.
Key words: Lactobacillus, Sausage, dairy products, Infant feces, Probiotics.
Proyecto INIA CAL01-026.