Molecular insight into the dynamic central metabolic pathways of Achromobacter xylosoxidans CF-S36 during heterotrophic nitrogen removal processes

Abstract

Organic carbon sources play a significant role in heterotrophic nitrogen consumption. This quintessential exploration is focused on carbon and nitrogen biogeochemical cycles in heterotrophic bacteria, capable of simultaneous nitrification and denitrification (SND). A heterotrophic bacterial strain Achromobacter xylosoxidans CF-S36 isolated from domestic wastewater efficiently eliminated ammonia, nitrate and nitrite by utilizing different carbon sources. The type of carbon utilized by strain CF-S36 determined the rate of heterotrophic nitrogen removal. Quantitative real-time PCR (qRT-PCR) analysis of genes of central carbon and nitrogen metabolism, signal transduction, electron transport chain (ETC) pathways and assays of enzymes of denitrification processes revealed the existence of well-coordinated link between carbon utilization and nitrogen elimination in bacterial cell. The most preferred carbon source for nitrification was succinate followed by glucose and acetate. Inhibitory effect of nitrite on glycolytic pathway and nitrogen assimilation genes attributes glucose as unfavorable carbon source for denitrification process in strain CF-S36. Acetate served as efficient carbon source for utilizing nitrite through denitrification process. The study demonstrated here might be useful to biogeochemical engineer to understand the involvement of heterotrophic bacteria in global biogeochemical cycle and to gain further insight into the diversified application of these microorganisms.

Keywords: Achromobacter xylosoxidans; Aerobic denitrification; Gene expression; Heterotrophic nitrification; Quantitative real-time PCR.