Diversity and evolutionary aspects of mucin binding (MucBP) domain repeats among Lactobacillus plantarum group strains through comparative genetic analysis

Mucin binding protein (Mub) of Lactobacillus plantarum- group (LPG) is considered as a potential marker gene due to its diversity and adherence property to host intestinal layer. We recently observed strain specific diversity in mub gene of LPG strains (n = 8) and grouped them into Type I, II and III based on the insertion and/or deletion of MucBP domain repeats (Devi et al., 2016). The mub gene expression pattern noted by real-time PCR revealed 67.64 increased fold change in MTCC 9483 with four MucBP repeats. Whereas, the isolates with 3 and 2 MucBP repeats showed ∼4 and 2 enhanced expression, respectively. Detection of integrase (int) and transposases (tra) in the flanking regions of mub, suggested variation in amplicon sizes and revealed strain diversity. The IS finder program identified tra nucleotide sequence similarity towards IS256 and IS5 family insertion elements that are present among other lactic acid bacteria. Phylogenetic dendrogram suggested the evolution of D7-D10 domains of L. paraplantarum MTCC 9483 from Lactobacillus namurensis, Lactobacillus hammesii and Lactobacillus spicheri. These results collectively gave information on the genetic diversity, functional MucBP domains and also facilitated in the selection of an efficient novel LPG strain with good adherence ability.