Isolation and identification of the dominant Lactobacillus in gut and faeces of pigs using carbohydrate fermentation and 16S rDNA analysis

The gut contents and faeces of 9 adult pigs and 387 colonies growing on MRS culture (selective for Lactobacillus) were sampled to isolate and identify Lactobacillus species present. The results showed that the number of bacteria growing on MRS culture increased from the anterior to posterior of the gut and decreased in the faeces (e.g., stomach, 4.04×105 cfu/g; small intestine, 9.77×107 cfu/g; large intestine 3.85×1011 cfu/g; faeces, 1.22×1011 cfu/g). Fifty-two lactobacilli-like colonies were selected from 387 on the basis of their size and Gram staining, and used for the fermentation of 11 carbohydrates, from which 12 lactobacilli were selected for 16S rDNA analysis. The result showed that Lactobacillus ruminis was the dominant Lactobacillus in the stomach, small intestine, large intestine and faeces of pigs. The identification of most strains estimated by their 16S rDNA was 98-99% accurate.