Microbacterium paulum sp. nov., isolated from microfiltered milk

A novel Gram-stain-\r\npositive,\r\nstrictly aerobic, short rod-shaped\r\nbacterium, designated 2CT, was isolated from freshly packaged\r\nmicrofiltered milk. This strain was able to grow within the NaCl concentration range of 0–5 % (w/v), temperature range of\r\n8–37 °C (optimally at 30 °C) and at pH 6.0–10.0. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain\r\n2CT was closely related to species of the genus Microbacterium, with the highest sequence similarity (99.2 %) to Microbacterium\r\nlacticum DSM 20427T as well as Microbacterium flavum DSM 18909T (=YM18-098T).\r\nThe phylogenetic tree based on 16S rRNA\r\ngenes showed that strain 2CT clustered with M. flavum DSM 18909T. However, the phylogenetic tree based on concatenated 16S\r\nrRNA and four housekeeping genes showed that strain 2CT clustered with M. lacticum DSM 20427T. Furthermore, the phylogenomic\r\ntree showed that strain 2CT clustered with M. lacticum DSM 20427T and M. flavum DSM 18909T. The major respiratory\r\nquinones were MK-10,\r\nMK-11\r\nand MK-12.\r\nThe predominant cellular fatty acids were anteiso-C\r\n15 : 0, iso-C\r\n16 : 0 and anteiso-C\r\n17 : 0. The\r\npolar lipid composition of strain 2CT consisted of diphosphatidylglycerol, phosphatidylglycerol, three unidentified glycolipids\r\nand two unidentified lipids. The cell-wall\r\npeptidoglycan type was a variant of B1α {Gly} [l-Lys]\r\nd-Glu-\r\nl-\r\nLys,\r\nwith the amino acids\r\nlysine, glycine, alanine and glutamic acid. The whole-cell\r\nsugars consisted of galactose, glucose, ribose and minor amounts\r\nof rhamnose. In addition, strain 2CT showed a glycolyl-type\r\ncell wall. The genomic DNA G+C content was 69.8 mol%, while the\r\naverage nucleotide identity (ANI) and digital DNA-DNA\r\nhybridization (dDDH) values with the closely related Microbacterium\r\nspecies were below the recognized thresholds of 95–96 % ANI and 70 % DDH for species definition. Based on the phenotypic and\r\ngenotypic data, strain 2CT (=LMG 32277T=CECT 30329T) is considered to represent a new species, for which the name Microbacterium\r\npaulum sp. nov. is proposed.