Fig. 3.

Distribution of colistin (a), phenicol (b), rifampin (c), and fosfomycin (d) resistance genes in 3S metagenome. Colistin resistance genes are dominated by the mobilized colistin resistance (mcr) determinants, mcr-1 and mcr-3. Based on phenicol resistance mechanisms, 31 genes (cat, cmlV, cpt) are responsible for phenicol inactivation, while 18 genes (cmlA, cmlB, cmlR, cmr, cmrA, bcr1, dha1, fexA, floR, pexA) are responsible for phenicol efflux. Rifampin-inactivating phosphotransferase (rph, rphD) dominated rifampin resistance genes in 3S, however, all the resistance genes inactivate rifampin antibiotic. Fosfomycin resistance genes include fosfomycin modifying genes (fosA, fosB, fosC, fosD, fosE, fosF, fosG, fosH, fosX) and the fosfomycin kinases (fomA, fomB, fomC)