The occurrence of off-flavor problems caused by prokaryotes cyanobacteria and actinomycetes is a worldwide water and food quality issue. Based on literatures on two earthy-muddy-smelling metabolites, （ i. e. , geosmin and 2- methylisoborneol （2-MIB）） , we reviewed their chemical characteristics, biosynthetic pathways, genes and enzymes that are involved in biosynthesis. Then we discussed current research questions related to off-flavor and future directions. Finally, we addressed the significance of probable key regulatory mechanism for the...
