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

Abstract

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 Cellulomonas 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 zntAY8, copAY8, HMTY8, and czcDY8, were subjected to functional exploration. Quantitative PCR determination of in vivo expression showed that zntAY8, copAY8, and HMTY8 were strongly Cd-inducible. Expression of the three inducible genes against time and Cd concentrations were further quantified. It is found that zntAY8 responded more strongly to higher Cd concentrations, while expression of copAY8 and HMTY8 increased over time at lower Cd concentrations. Heterologous expression of the four genes in Cd-sensitive Escherichia coli led to different impacts on hosts’ Cd sorption, with an 87% reduction by zntAY8 and a 3.7-fold increase by HMTY8. In conclusion, a Cd-resistant Cellulomonas 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 Cellulomonas genus.

Analysis of the Cadmium Removal Mechanism of Human Gut Bacteria Enterococcus faecalis Strain ATCC19433 from a Genomic Perspective

“…The genome contains 2,522 annotated genes (CdSs) with speci c physiological functions, accounting for 88.27% of the entire genome, as annotated in various databases (Table S2). The circular genome map of Enterococcus faecalis strain ATCC19433 provides an overview of key genomic features, including the distribution of genes on both the positive and antisense strands, COG functional annotation of genes, G + C content, homologous genes, and les for rRNA and tRNA, which could support research on the mechanism of Cd resistance and binding [50].…”

Pseudomonas aeruginosa strain CD3 implements cadmium resistance through multimodal systems and its regulatory networking

“…Firstly, the speci c mechanisms of cadmium resistance in bacteria are not understood comprehensibly. While certain genes associated with cadmium resistance, such as czcC, czcB, czcA, czcR, czcS, cadA and cadR, have been identi ed, there might be many other genes involved (Abbas et al 2018;Qin et al 2019;Chen et al 2022). Secondly, the role of time and dosage related to cadmium resistance is still questionable.…”

“…H 2 O. The cellular response in making the defence system ready for cadmium assaults is modulated differentially when grown in lower concentrations of Cd 2+ , indicating that lower cadmium concentrations can activate e ux mechanisms more effectively in lesser preparatory time(Chen et al 2022), especially when shifted to a fresh medium with abruptly high cadmium (1.5 mM).This study has also described the effect of zinc or cobalt concentrations in the pre-culture (i.e., zinc or cobaltinduced cells) on cadmium resistance in CD3. It was shown that the cells' resistance to cadmium was in uenced by pre-growing them in the presence of ZnSO 4 .7H 2 O (0.25 mM).…”