Lactobacillus tucceti sp. nov., a new lactic acid bacterium isolated from sausage

A taxonomic note on the genus Lactobacillus: Description of 23 novel genera, emended description of the genus Lactobacillus Beijerinck 1901, and union of Lactobacillaceae and Leuconostocaceae

The genus Lactobacillus comprises 261 species (at March 2020) that are extremely diverse at phenotypic, ecological and genotypic levels. This study evaluated the taxonomy of Lactobacillaceae and Leuconostocaceae on the basis of whole genome sequences. Parameters that were evaluated included core genome phylogeny, (conserved) pairwise average amino acid identity, clade-specific signature genes, physiological criteria and the ecology of the organisms. Based on this polyphasic approach, we propose reclassification of the genus Lactobacillus into 25 genera including the emended genus Lactobacillus, which includes host-adapted organisms that have been referred to as the Lactobacillus delbrueckii group, Paralactobacillus and 23 novel genera for which the names Holzapfelia, Amylolactobacillus, Bombilactobacillus, Companilactobacillus, Lapidilactobacillus, Agrilactobacillus, Schleiferilactobacillus, Loigolactobacilus, Lacticaseibacillus, Latilactobacillus, Dellaglioa, Liquorilactobacillus, Ligilactobacillus, Lactiplantibacillus, Furfurilactobacillus, Paucilactobacillus, Limosilactobacillus, Fructilactobacillus, Acetilactobacillus, Apilactobacillus, Levilactobacillus, Secundilactobacillus and Lentilactobacillus are proposed. We also propose to emend the description of the family Lactobacillaceae to include all genera that were previously included in families Lactobacillaceae and Leuconostocaceae. The generic term 'lactobacilli' will remain useful to designate all organisms that were classified as Lactobacillaceae until 2020. This reclassification reflects the phylogenetic position of the micro-organisms, and groups lactobacilli into robust clades with shared ecological and metabolic properties, as exemplified for the emended genus Lactobacillus encompassing species adapted to vertebrates (such as Lactobacillus delbrueckii, Lactobacillus iners, Lactobacillus crispatus, Lactobacillus jensensii, Lactobacillus johnsonii and Lactobacillus acidophilus) or invertebrates (such as Lactobacillus apis and Lactobacillus bombicola).

Lactobacillus terrae sp. nov., a novel species isolated from soil samples in the Republic of Korea

A novel strain, designated NIBRBAC000499792^T, was isolated from a soil sample collected at Jukgye, Dongnam, Cheonan, Republic of Korea. Cells were Gram-positive, non-motile, non-spore-forming, rod-shaped, oxidase-negative and catalase-negative. Colonies grown on de Man, Rogosa and Sharpe agar were white, circular, raised and entire. Analysis of the 16S rRNA gene sequence analysis revealed that strain NIBRBAC000499792^T belongs to the genus Lactobacillus (family Lactobacillaceae) and is most closely related to Lactobacillus nodensis DSM 19682^T (96.1 % similarity) and Lactobacillus tucceti KCTC 21005^T (96.7 %). The results of DNA-DNA hybridization experiments demonstrated that strain NIBRBAC000499792^T represents a novel species. Major fatty acids are C18 : 1ω9c, C16 : 0 and unidentified 18.846 and/or C19 : 1ω6c and/or C19 : 0cyclo. The predominant respiratory quinones are menaquinone-8 and menaquinone-9. The major polar lipids are phosphatidylglycerol and diphosphatidylglycerol. The minor polar lipids are one unidentified aminophospholipid, one unidentified phospholipid, and four unidentified lipids. Next-generation sequencing analysis of strain NIBRBAC000499792^T indicated that the total genome size was 1 548 794 bp with a G+C content of 33.1 mol%, 1586 coding sequences, 50 tRNAs and nine rRNAs. The most closely related genomes belonged to Lactobacillus species. Most metabolic pathways were related to carbon metabolism and carbon fixation. Based on this polyphasic analysis, strain NIBRBAC000499792^T represents a novel species of the genus Lactobacillus, for which the name Lactobacillus terrae sp. nov. is proposed, with the type strain NIBRBAC000499792^T (=KCTC 21093^T=JCM 32269^T).

Lactobacillus allii sp. nov. isolated from scallion kimchi

A novel strain of lactic acid bacteria, WiKim39^T, was isolated from a scallion kimchi sample consisting of fermented chili peppers and vegetables. The isolate was a Gram-positive, rod-shaped, non-motile, catalase-negative and facultatively anaerobic lactic acid bacterium. Phylogenetic analysis of the 16S rRNA gene sequence showed that strain WiKim39^T belonged to the genus Lactobacillus, and shared 97.1–98.2 % pair-wise sequence similarities with related type strains, Lactobacillus nodensis, Lactobacillus insicii, Lactobacillus versmoldensis, Lactobacillus tucceti and Lactobacillus furfuricola. The G+C content of the strain based on its genome sequence was 35.3 mol%. The ANI values between WiKim39^T and the closest relatives were lower than 80 %. Based on the phenotypic, biochemical, and phylogenetic analyses, strain WiKim39^T represents a novel species of the genus Lactobacillus, for which the name Lactobacillus allii sp. nov. is proposed. The type strain is WiKim39^T (=KCTC 21077^T=JCM 31938^T).

Characterisation of biofilms formed by Lactobacillus plantarum WCFS1 and food spoilage isolates

Lactobacillus plantarum has been associated with food spoilage in a wide range of products and the biofilm growth mode has been implicated as a possible source of contamination. In this study we analysed the biofilm forming capacity of L. plantarum WCFS1 and six food spoilage isolates. Biofilm formation as quantified by crystal violet staining and colony forming units was largely affected by the medium composition, growth temperature and maturation time and by strain specific features. All strains showed highest biofilm formation in Brain Heart Infusion medium supplemented with manganese and glucose. For L. plantarum biofilms the crystal violet (CV) assay, that is routinely used to quantify total biofilm formation, correlates poorly with the number of culturable cells in the biofilm. This can in part be explained by cell death and lysis resulting in CV stainable material, conceivably extracellular DNA (eDNA), contributing to the extracellular matrix. The strain to strain variation may in part be explained by differences in levels of eDNA, likely as result of differences in lysis behaviour. In line with this, biofilms of all strains tested, except for one spoilage isolate, were sensitive to DNase treatment. In addition, biofilms were highly sensitive to treatment with Proteinase K suggesting a role for proteins and/or proteinaceous material in surface colonisation. This study shows the impact of a range of environmental factors and enzyme treatments on biofilm formation capacity for selected L. plantarum isolates associated with food spoilage, and may provide clues for disinfection strategies in food industry.

Lactobacillus bombi sp. nov., from the digestive tract of laboratory-reared bumblebee queens (Bombus terrestris)

Three bacterial strains belonging to the genus Lactobacillus were isolated from the digestive tracts of laboratory-reared bumblebee queens (Bombus terrestris) using MRS agar under anaerobic conditions. The isolates were identified according to 16S rRNA gene sequence analysis as undescribed members of the genus Lactobacillus , with the highest 16S rRNA gene sequence similarity (96.9 %) to the uncharacterized bacterial strain Lactobacillus sp. Mboho2r2 isolated from the stomach of a European honeybee (Apis mellifera). Lactobacillus tucceti was found to be the closest related species with a validly published name, with 92.9 % 16S rRNA gene sequence similarity to the type strain. However, phylogenetic analyses based on different markers revealed that this species is phylogenetically very distant from the novel strains. The DNA G+C content of the proposed type strain BTLCH M1/2T is 37.8 mol%. The fatty acids C19 : 1ω6c and/or C19 : 0 cyclo ω10c/19ω6, C18 : 1ω9c and C16 : 0 were predominant in all strains. Diphosphatidylglycerol, phosphatidylglycerol, a phospholipid, seven glycolipids and two phosphoglycolipids were detected in the novel strains. Growth was observed at 47 °C. The peptidoglycan type A4α l-Lys–d-Asp was determined for strain BTLCH M1/2T. Genotypic characteristics and phylogenetic analyses based on the phylogenetic markers hsp60, pheS, rpoA and tuf as well as phenotypic characteristics and the results of chemotaxonomic analyses confirmed that the new isolates belong to a novel species of the genus Lactobacillus , for which the name Lactobacillus bombi sp. nov. is proposed. The type strain is BTLCH M1/2T ( = DSM 26517T = CCM 8440T).

Lactobacillus furfuricola sp. nov., isolated from Nukadoko, rice bran paste for Japanese pickles

Two strains of lactic acid bacteria, Nu27T and Nu29, were isolated from Nukadoko, rice bran paste for Japanese pickles. The isolates were Gram-stain-positive, rod-shaped, catalase-negative, non-motile and facultatively anaerobic lactic acid bacteria. The isolates showed identical 16S rRNA gene sequences. The closest relatives to strain Nu27T based on 16S rRNA gene sequence similarities were Lactobacillus versmoldensis KU-3T (98.9 % 16S rRNA gene sequence similarity), Lactobacillus nodensis iz4bT (96.3 %) and Lactobacillus tucceti CECT 5290T (97.2 %). DNA–DNA relatedness values revealed genotype separation of the two isolates from the above three species. Based on the physiological, biochemical and genotypic characteristics provided, the isolates represent a novel species of the genus Lactobacillus , for which name is Lactobacillus furfuricola proposed. The type strain is Nu 27T ( = JCM 18764T = NRIC 0900T = DSM 27174T).