Taxonomic identification, genomic analysis, and optimized chromium(VI) bioreduction by Microbacterium triticisoli sp. nov. M28T.

Strain M28T was isolated from subsoil obtained from decaying wheat straw. Cells were Gram-positive, non-motile, short rod-shaped and formed yellowish colonies on lysogeny broth (LB) agar. The strain was able to grow at 0-8% (w/v) NaCl , 15-40 °C and pH 5.5-10.0. Phylogenetic analysis based on 16S rRNA gene sequences, core genes and whole-genome indicated that strain M28T belonged to the genus Microbacterium but was distinct from all known strains in this genus. Based on phenotypic, genotypic, chemical taxono mic and phylogenetic analyses, strain M28T is a representative of a new species of Microbacterium, which is proposed to be named Microbacterium triticisoli sp. nov., the type strain is M28T (=CCTCC AA 2022021T =JCM 35796T). Genomic analysis revealed multiple metal resistance systems, antibiotic resistance determinants and oxidative stress defense genes, explaining its exceptional environmental adaptability. Notably, the strain reduced 99% of 50 mg/L Cr(VI) within 24 h under optimized conditions (37 °C, pH 7.0, 2.5 g/L sucrose) and tolerated Cr(VI) concentrations up to 125 mg/L. This study identifies M. triticisoli as a promising agent for chromium bioremediation, providing a foundation for engineering microbial solutions to heavy metal pollution.