Impact of mixed carbon sources on microbial function and network structure in hypersaline denitrification

Abstract

This study evaluated denitrification systems using two carbon sources: glucose alone (G), and a mixture of glucose, methanol, and sodium acetate (GMS), treating synthetic saline wastewater to prove the superior operational efficiency of the mixed carbon sources. Both systems showed excellent nitrogen removal under 80 gNaCl L-1, but the glucose-based system exhibited unstable nitrate removal at a low C/N ratio of 3. Microbial community composition was distinct between the systems. The GMS system showed the highest organic removal due to the abundance of Marinobacter spp., and the prediction of functional genes using phylogenetic investigation of communities by reconstruction of unobserved states (PICRUSt) showed an increase of denitrifying genes such as nitrate (Nar), and nitrite (Nir) reductase in GMS. Co-occurrence network analysis revealed that GMS guaranteed diverse microbial interactions and stable network structure, facilitating enhanced denitrifica- tion capability. This study offers engineering insights into microbial denitrification under hypersaline conditions.