Affiliation:
1. Nihon Shokuhin Kako Co. LTD, 30, Tajima, Fuji, Shizuoka 417-8530, Japan
2. Innovative Animal Production System, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8571, Japan
3. Department of Informatics, National Institute of Genetics, Mishima, Shizuoka 411-8540, Japan
4. Institute of Livestock and Grassland Science, National Agriculture and Food Research Organization, Nasushiobara, Tochigi 329-2793, Japan
5. Research Center of Genetic Resources, National Agriculture and Food Research Organization, Tsukuba, Ibaraki 305-8602, Japan
Abstract
Seven novel lactic acid bacterial strains (BF125T, BF186, TKL145, YK3, YK6, YK10 and NSK) were isolated from the fresh faeces of Japanese black beef cattle and weanling piglets, spent mushroom substrates, or steeping water of a corn starch production plant. These strains are rod-shaped, Gram-stain-positive, non-motile, non-spore-forming, catalase-negative, cytochrome oxidase-negative, facultatively anaerobic, and homofermentative. Strain BF125T did not produce any gas from glucose; both d- and l-lactate were produced as end-products of glucose (D/L, 40 : 60). Growth occurred at 30–45 °C (optimum, 37 °C), pH 5.0–8.0 (optimum, pH 6.0), and with NaCl concentration of 1.0–3.0% (w/v). The G+C content of genomic DNA of strain BF125T was 37.8 mol% (whole-genome analysis). The major fatty acids were C16 : 0, C18 : 1 ω9c, C19 cyclopropane 9, 10, and summed feature 10. The 16S rRNA gene in strain BF125T showed high similarity to that of the type strain of Lactobacillus amylovorus (99.93%), and the other isolates were also identified as L. amylovorus based on these similarities. A phylogenetic tree based on the core genomes of L. amylovorus strains (n=54), including the seven isolates, showed that they could be divided into two clusters. Strains YK3, YK6, YK10, and NSK were in the first cluster, along with the type strain DSM 20531T, while the second cluster included isolates BF125T, BF186, TKL145, and other strains isolated from various animal origins. Phenotypic differences in fermentability were observed for lactose, salicin, and gentiobiose between these two groups. The intergroup digital DNA–DNA hybridization values (72.9–78.6%) and intergroup average nucleotide identity values (95.64–96.92%) were comparable to values calculated using datasets of other valid subspecies of the genus (ex-) Lactobacillus. In light of the physiological, genotypic, and phylogenetic evidence, we propose a novel subspecies of L. amylovorus, named Lactobacillus amylovorus subsp. animalis subsp. nov. (type strain BF125T=MAFF 212522T=DSM 115528T). Our findings also led to the automatic creation of Lactobacillus amylovorus subsp. amylovorus subsp. nov. and an emended description of the species L. amylovorus.
Funder
National Agriculture and Food Research Organization