Synchronous microbial V(V) reduction and denitrification using corn straw as the sole carbon source

The coexistence of nitrate and V(V) in groundwater aquifers poses potential threats to ecological environment and pub-lic health. However, much remains to be elucidated about how the complex microbial community coupled nitrate and V(V) simultaneous bio-reduction with carbon source oxidation. For the first time, it was demonstrated that denitrifica-tion and V(V) bio-reduction occur by using corn straw as the sole carbon and energy source. Corn straw was proved to have efficient denitrification and V(V) bio-reduction performance in various environments, especially at V (V) concentrations of 100 mg/L for optimal V(V) reduction rate (19.25 mg/Lid) and at pH of 11 with the best nitrate reduction rate (3.12 d-1). In addition, an interesting phenomenon was found that the release of V(V) occurred when the carbon source was insufficient and the competitive electron acceptor (NO3--N) existed. Metagenomic analysis showed that the addition of corn straw increased the abundance of genes related to metal resistance, cytochrome and dimethyl sulfoxide, and increased the abundance of glycolytic process, which may play a vital role in facilitating the reduction of V(V). These findings can provide basic suggestions for improving the mechanism of V(V) reduction pathway and provide guidance for the remediation of groundwater polluted by nitrate and V(V).

Automated summary

The coexistence of nitrate and V(V) in groundwater poses potential threats to the environment and public health. For the first time, it has been shown that denitrification and V(V) bio-reduction can occur simultaneously using corn straw as the carbon and energy source. Corn straw has been proven to be efficient in denitrification and V(V) bio-reduction in various environments.