RESEARCH ARTICLE The evolution and popula r e

Lactobacillus fermentum is an economically important species of lactic acid bacterium (LAB) used in the produc-by Rogosa et al., (1953) is also heterofermentative and DNA-DNA hybridization studies showed it to be very simi-Dan et al. BMC Microbiology (2015) 15:107 DOI 10.1186/s12866-015-0447-zARDRA), pulsed-field gel electrophoresis with restrictionof P. R. China, Department of Food Science and Engineering, Inner Mongolia Agricultural University, Hohhot 010018, P. R. Chination and preservation of fermented food as an acid-producing starter culture [1, 2]. Isolates of L. fermentum originate from a variety of habitats: traditionally fermented milk products, sourdough, fermenting plant materials, faeces and sewage amongst others [3–8]. Lactobacillus fermentum was first described by Beijerink (1901), as an obligate heterofermentative bacterium associated with the fermentation of hexoses to lactic acid [9, 10]. Another lar to L. fermentum [11, 12]. There is now strong evidence to support a close relationship between L. cellobiosus and L. fermentum and, in fact, L. cellobiosus has now been re-classified as a biovar of L. fermentum [5, 13]. In recent years, molecular typing approaches have been used to characterize L. fermentum and the subspe-cies within it. For example, L. fermentum isolates could be differentiated from other Lactobacillus species using randomly amplified polymorphic DNA(RAPD-PCR) methods [14, 15]. RAPD-PCR has also been used in combination with amplified 16S rDNA restriction analysis (16S