Transcriptomics extract the key chromium resistance genes of Cellulomonas

Abstract Cellulomonas fimi Clb-11 can reduce high toxic Cr (VI) to low toxic Cr (III). In this study, transcriptomics was used to analyze the key genes, which was involved in Cr (VI) uptake and reduction in C. fimi Clb-11. The results showed that when C. fimi Clb-11 was subjected to 0.5 mM Cr (VI) stress, 654 genes were upregulated. Among them, phosphate transport protein encoding gene phoU, inorganic phosphate transport protein encoding gene TC.PIT, and molybdate transport protein encoding genes modA, modB, and modC were involved in the passive uptake of Cr (VI) by C. fimi Clb-11. Cytochrome c subunits encoding genes qcrA and qcrC, as well as cytochrome c oxidase subunits encoding genes coxB and coxC were involved in the intracellular reduction of Cr (VI) by C. fimi Clb-11. Additionally, several unreported genes were found to be upregulated in C. fimi Clb-11 under Cr (VI) stress. Manganese transport protein encoding gene mntH and nickel transport system permease encoding genes ABC.PE.P and ABC.PE.P1 may participate in the passive uptake of Cr (VI) by C. fimi Clb-11. Osmoprotectant transport system ATP-binding protein encoding gene opuA, osmoprotectant transport system substrate-binding protein encoding gene opuC, and osmoprotectant transport system permease encoding gene opuBD may be crucial for maintaining intracellular water content in cells and enhancing the resistance of C. fimi Clb-11 to Cr (VI). Proton pump subunit encoding genes atpA, atpB, atpE, atpF, and atpH, as well as sodium-hydrogen antiporter subunit encoding genes mnhA and mnhC, may be involved in the extracellular proton secretion to reduce Cr (VI) in extracellular. Iron complex transport system substrate-binding protein encoding gene ABC.FEV.S, vacuolar iron transporter encoding gene VIT, FMN reductase gene encoding gene ssuE, and quinone oxidoreductase QOR encoding genes qor and qorB may participate in the intracellular reduction of Cr (VI) by C. fimi Clb-11. The pyruvate dehydrogenase encoding genes pdhA, pdhB, and pdhC, as well as the succinate dehydrogenase encoding genes sdhA, sdhB, and sdhD, may play important roles in supplying electrons for C. fimi Clb-11 to reduce Cr (VI). Our study provides theoretical references for optimizing microbial Cr (VI) resistance and microbial chromium pollution remediation techniques.