A novel multi-locus sequence typing (MLST) protocol for Leuconostoc lactis isolates from traditional dairy products in China and Mongolia

Abstract

BackgroundEconomically, Leuconostoc lactis is one of the most important species in the genus Leuconostoc. It plays an important role in the food industry including the production of dextrans and bacteriocins. Currently, traditional molecular typing approaches for characterisation of this species at the isolate level are either unavailable or are not sufficiently reliable for practical use. Multilocus sequence typing (MLST) is a robust and reliable method for characterising bacterial and fungal species at the molecular level. In this study, a novel MLST protocol was developed for 50 L. lactis isolates from Mongolia and China.ResultsSequences from eight targeted genes (groEL, carB, recA, pheS, murC, pyrG, rpoB and uvrC) were obtained. Sequence analysis indicated 20 different sequence types (STs), with 13 of them being represented by a single isolate. Phylogenetic analysis based on the sequences of eight MLST loci indicated that the isolates belonged to two major groups, A (34 isolates) and B (16 isolates). Linkage disequilibrium analyses indicated that recombination occurred at a low frequency in L. lactis, indicating a clonal population structure. Split-decomposition analysis indicated that intraspecies recombination played a role in generating genotypic diversity amongst isolates.ConclusionsOur results indicated that MLST is a valuable tool for typing L. lactis isolates that can be used for further monitoring of evolutionary changes and population genetics.

Culture-independent bacterial community profiling of carbon dioxide treated raw milk

“…lactis is often isolated from fermented foods including traditional fermented milk products and brined products such as kimchi and stinky tofu (Dan et al, 2014;Liu et al, 2011). It is also important for aroma and texture production in dairy products (Hemme and Foucaud-Scheunemann, 2004;Marshall, 1987).…”

“…Pyrosequencing has already been used in a large number of recent studies in which the microbial communities of dairy products were characterised, including raw and pasteurised milk and various types of cheese (Aldrete-Tapia et al, 2014;de Filippis et al, 2014;de Pasquale et al, 2014;Ercolini et al, 2012;Guidone et al, 2016;Masoud et al, 2011;Masoud et al, 2012;Quigley et al, 2013a;Quigley et al, 2012;Riquelme et al, 2015). We have recently analysed the bacterial populations of fresh and spoiled carbonated raw sweet whey using pyrosequencing of 16S rRNA gene amplicons (Lo et al, 2016).…”

Genetic relationships among Enterococcus faecalis isolates from different sources as revealed by multilocus sequence typing

“…Each isolate was cultured overnight at 37°C in M17 broth and then the total genomic DNA was extracted using the methods described by Dan et al (2014).…”

Multilocus sequence typing of Lactobacillus casei isolates from naturally fermented foods in China and Mongolia

“…Several MLST schemes have also been developed for species of LAB, including Lb. casei (Cai et al, 2007;Diancourt et al, 2007), Lactobacillus acidophilus (Ramachandran et al, 2013), Lactobacillus delbrueckii (Tanigawa and Watanabe, 2011), Lactobacillus plantarum (de Las Rivas et al, 2006;Tanganurat et al, 2009), Lactobacillus sanfranciscensis (Picozzi et al, 2010), Lactobacillus helveticus , Lactobacillus sakei (Chaillou et al, 2013), Lactococcus lactis , and Leuconostoc lactis (Dan et al, 2014). In these studies, strains were classified with high resolution by using MLST based on the analysis of housekeeping gene sequences, including aroE,ddl,dnaE,fusA,ftsZ,glnA,gyrB,glpF,gltX,gyrB,gpd,gdh,hemN,hsp60,ileS,lepA,leuS,ldhL,mutS,mutL,metRS,nrdD,pepV,pgm,polA,recA,recG,recP,xpt,yqil,tkt,and tpi.…”