AUTHOR=Chen Jinghao , Wang Likun , Li Wenjun , Zheng Xin , Li Xiaofang 

TITLE=Genomic Insights Into Cadmium Resistance of a Newly Isolated, Plasmid-Free Cellulomonas sp. Strain Y8

JOURNAL=Frontiers in Microbiology

VOLUME=12

YEAR=2022

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2021.784575

DOI=10.3389/fmicb.2021.784575

ISSN=1664-302X

ABSTRACT=<p>Our current knowledge on bacterial cadmium (Cd) resistance is mainly based on the functional exploration of specific Cd-resistance genes. In this study, we carried out a genomic study on Cd resistance of a newly isolated <italic>Cellulomonas</italic> strain with a MIC of 5 mM Cd. Full genome of the strain, with a genome size of 4.47 M bp and GC-content of 75.35%, was obtained through high-quality sequencing. Genome-wide annotations identified 54 heavy metal-related genes. Four potential Cd-resistance genes, namely <italic>zntAY8</italic>, <italic>copAY8</italic>, <italic>HMTY8</italic>, and <italic>czcDY8</italic>, were subjected to functional exploration. Quantitative PCR determination of <italic>in vivo</italic> expression showed that <italic>zntAY8, copAY8</italic>, and <italic>HMTY8</italic> were strongly Cd-inducible. Expression of the three inducible genes against time and Cd concentrations were further quantified. It is found that <italic>zntAY8</italic> responded more strongly to higher Cd concentrations, while expression of <italic>copAY8</italic> and <italic>HMTY8</italic> increased over time at lower Cd concentrations. Heterologous expression of the four genes in Cd-sensitive <italic>Escherichia coli</italic> led to different impacts on hosts’ Cd sorption, with an 87% reduction by <italic>zntAY8</italic> and a 3.7-fold increase by <italic>HMTY8</italic>. In conclusion, a Cd-resistant <italic>Cellulomonas</italic> sp. strain was isolated, whose genome harbors a diverse panel of metal-resistance genes. Cd resistance in the strain is not controlled by a dedicated gene alone, but by several gene systems collectively whose roles are probably time- and dose-dependent. The plasmid-free, high-GC strain Y8 may provide a platform for exploring heavy metal genomics of the <italic>Cellulomonas</italic> genus.</p>