Abstract
Lactobacillus rossiae is an obligately hetero-fermentative lactic acid bacterium, which can be isolated from a broad range of environments including sourdoughs, vegetables, fermented meat and flour, as well as the gastrointestinal tract of both humans and animals. In order to unravel distinctive genomic features of this particular species and investigate the phylogenetic positioning within the genus Lactobacillus, comparative genomics and phylogenomic approaches, followed by functional analyses were performed on L. rossiae DSM 15814T, showing how this type strain not only occupies an independent phylogenetic branch, but also possesses genomic features underscoring its biotechnological potential. This strain in fact represents one of a small number of bacteria known to encode a complete de novo biosynthetic pathway of vitamin B12 (in addition to other B vitamins such as folate and riboflavin). In addition, it possesses the capacity to utilize an extensive set of carbon sources, a characteristic that may contribute to environmental adaptation, perhaps enabling the strain's ability to populate different niches.
Highlights
Lactobacillus rossiae is an obligately hetero-fermentative lactic acid bacterium, exhibiting close phylogenetic relationship with Lactobacillus durianis, Lactobacillus malefermentans and Lactobacillus suebicus
Analysis of L. rossiae DSM 15814T, a sourdough strain, revealed a minimum predicted genome size of 2,870,031 bp, encoding relatively high numbers of genes involved in carbohydrate and amino acid transport and metabolism, stress resistance, transcriptional regulation and signal transduction
Phylogenomic and comparative analyses, the L. rossiae taxon forms an independent phylogenetic branch, in close proximity to the L. reuteri, L. fermentum, L. plantarum and L. brevis groups, which suggests that these species all adopted a similar strategy for phylogenetic evolution and environmental adaptation
Summary
Lactobacillus rossiae (formerly Lactobacillus rossii, designated a novel species in 2005 [1],) is an obligately hetero-fermentative lactic acid bacterium, exhibiting close phylogenetic relationship with Lactobacillus durianis, Lactobacillus malefermentans and Lactobacillus suebicus. The ability of Lactobacillus spp. to adapt to different environments is variable: some species are isolated from diverse habitats, while others appear to be restricted to specific niches [11] The latter situation applies to Lactobacillus sanfranciscensis, which has so far only been found in sourdoughs. Loss of genes involved in carbohydrate metabolism and biosynthesis of amino acids and cofactors, and acquisition of genes required for peptide transport and hydrolysis have been described in lactic acid bacteria [14,15]. Species such as Lactobacillus gasseri and Lactobacillus johnsonii, which are commonly found in the gastrointestinal tract, carry genetic features that contribute to gut survival and promote interactions with intestinal mucosa. Some strains have been identified based on their antifungal activity [17,18], and/or used for sourdough biotechnology, glutamate production [19] and fermentation of wheat germ [20]
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