AUTHOR=Deng Yang , Mou Tong , Wang Junhuan , Su Jing , Yan Yanchun , Zhang Yu-Qin 

TITLE=Characterization of three rapidly growing novel Mycobacterium species with significant polycyclic aromatic hydrocarbon bioremediation potential

JOURNAL=Frontiers in Microbiology

VOLUME=14

YEAR=2023

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2023.1225746

DOI=10.3389/fmicb.2023.1225746

ISSN=1664-302X

ABSTRACT=<p><italic>Mycobacterium</italic> species exhibit high bioremediation potential for the degradation of polycyclic aromatic hydrocarbons (PAHs) that are significant environmental pollutants. In this study, three Gram-positive, rapidly growing strains (YC-RL4<sup>T</sup>, MB418<sup>T</sup>, and HX176<sup>T</sup>) were isolated from petroleum-contaminated soils and were classified as <italic>Mycobacterium</italic> within the family <italic>Mycobacteriaceae</italic>. Genomic average nucleotide identity (ANI; &lt; 95%) and digital DNA–DNA hybridization (dDDH; &lt; 70%) values relative to other <italic>Mycobacterium</italic> spp. indicated that the strains represented novel species. The morphological, physiological, and chemotaxonomic characteristics of the isolates also supported their affiliation with <italic>Mycobacterium</italic> and their delineation as novel species. The strains were identified as <italic>Mycobacterium adipatum</italic> sp. nov. (type strain YC-RL4<sup>T</sup> = CPCC 205684<sup>T</sup> = CGMCC 1.62027<sup>T</sup>), <italic>Mycobacterium deserti</italic> sp. nov. (type strain MB418<sup>T</sup> = CPCC 205710<sup>T</sup> = KCTC 49782<sup>T</sup>), and <italic>Mycobacterium hippophais</italic> sp. nov. (type strain HX176<sup>T</sup> = CPCC 205372<sup>T</sup> = KCTC 49413<sup>T</sup>). Genes encoding enzymes involved in PAH degradation and metal resistance were present in the genomes of all three strains. Specifically, genes encoding alpha subunits of aromatic ring-hydroxylating dioxygenases were encoded by the genomes. The genes were also identified as core genes in a pangenomic analysis of the three strains along with 70 phylogenetically related mycobacterial strains that were previously classified as <italic>Mycolicibacterium</italic>. Notably, strain YC-RL4<sup>T</sup> could not only utilize phthalates as their sole carbon source for growth, but also convert di-(2-ethylhexyl) phthalate into phthalic acid. These results indicated that strains YC-RL4<sup>T</sup>, MB418<sup>T</sup>, and HX176<sup>T</sup> were important resources with significant bioremediation potential in soils contaminated by PAHs and heavy metals.</p>