Comparative genome analysis ofLactobacillus mudanjiangensis, an understudied member of theLactobacillus plantarumgroup

Abstract

The genus Lactobacillus is known to be extremely diverse and consists of different phylogenetic groups that show a diversity roughly equal to the expected diversity of a typical bacterial genus. One of the most prominent phylogenetic groups within this genus is the Lactobacillus plantarum group which contains the understudied Lactobacillus mudanjiangensis species. Before this study, only one L. mudanjiangensis strain, DSM 28402 T , was described but without whole-genome analysis. In this study, three strains classified as L. mudanjiangensis, were isolated from three different carrot juice fermentations and their whole-genome sequence was determined, together with the genome sequence of the type strain. The genomes of all four strains were compared with publicly available L. plantarum group genome sequences. This analysis showed that L. mudanjiangensis harbored the second largest genome size and gene count of the whole L. plantarum group. In addition, all members of this species showed the presence of a gene coding for a putative cellulose-degrading enzyme. Finally, three of the four L. mudanjiangensis strains studied showed the presence of pili on scanning electron microscopy (SEM) images, which were linked to conjugative gene regions, coded on plasmids in at least two of the strains studied. Author summaryLactobacillus mudanjiangensis is an understudied species within the Lactobacillus plantarum group. Since its first description, no other studies have reported its isolation. Here, we present the first four genome sequences of this species, which include the genome sequence of the type strain and three new L. mudanjiangensis strains isolated from fermented carrot juice. The genomes of all four strains were compared with publicly available L. plantarum group genome sequences. We found that this species February 5, 2019 1/20 harbored the second largest genome size and gene count of the whole L. plantarum group. Furthermore, we present the first scanning electron microscopy (SEM) images of L. mudanjiangensis, which showed the formation of pili in three strains that we linked to genes related to conjugation. Finally, we found the presence of a unique putative cellulose-degrading enzyme, opening the door for different industrial applications of these Lactobacillus strains. Introduction 1The genus Lactobacillus is known to be extremely diverse [1]. Furthermore, it has been 2 shown that different phylogenetic groups within this genus display a diversity roughly 3 equal to the expected diversity of a typical bacterial genus [2][3][4][5][6]. Each of these 4 phylogenetic groups can be recognized as an entity with unique properties and a distinct 5 natural history, ecology, function and physiology [5]. Therefore, the study of these 6 phylogenetic groups separately, as if they would be one genus, can be an interesting 7 approach that might reveal new, previously overlooked, phylogenetic relationships and 8 functional properties. 9 One of the more abundantly studied species within the genus Lactobacillus, is 10 Lactobacillus...

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