Response of denitrifying genes coding for nitrite (nirK or nirS) and nitrous oxide (nosZ) reductases to different physico-chemical parameters during agricultural waste composting

Abstract

The present research was performed to clarify the changes of denitrifying genes (nirK, nirS, and nosZ) abundances under different physico-chemical parameters through evaluating the relationships between the genes abundances and parameters during agricultural waste composting. The genes abundances were determined by real-time quantitative PCR (qPCR). The correlations between physico-chemical parameters and denitrifying genes abundances were analysed by regression analysis. qPCR results showed that the nosZ gene abundance was higher than that of nirK and nirS genes. The nirK gene abundance was higher than nirS gene indicating that nitrite reducers with Cu-containing enzyme encoded by nirK gene were more of importance than those with cytochrome cd1 nitrite reductase encoded by nirS gene in the nitrite reduction step. Regression analysis suggested that (1) nirK gene abundance was correlated with pile temperature following quadratic model; (2) nirS gene abundance was linearly correlated with pile temperature and concentration of NH4 (+), while correlated with concentration of NO3 (-) and pH following inverse and quadratic model respectively; (3) nosZ gene abundance was quadratically correlated with pH and linearly correlated with water soluble carbon (WSC).

Microbial Abundances Predict Methane and Nitrous Oxide Fluxes from a Windrow Composting System

“…Consistent with the first hypothesis prediction, changes in physicochemical parameters shaped different time course patterns of CH 4 - and N 2 O-related functional genes (Gödde and Conrad, 1999; Holtan-hartwig et al, 2002; Kandeler et al, 2006; Zhou et al, 2011; Zhang et al, 2015). Correlation analyses showed that the abundance of pmoA , narG , nirK , and nirS genes shared negative correlations with pile temperature ( r = ∼-0.70, p < 0.05), moisture, TOC, and C/N ratio, and positive correlations with TN ( Figure 4 ), suggesting that changes in interacting physicochemical parameters in the pile shaped the dynamic pattern of the pmoA , narG , nirK , and nirS genes ( Figure 4 ), in line with the results obtained by Hallin et al (2009) showing that nitrate reducers and denitrifiers were closely related to soil TOC, TN, and C/N ratio in a 50-year-old fertilization experiment.…”

“…Similar relationships between methanotrophs abundances and abiotic parameters were found in landfill cover soils (Kumaresan et al, 2009; Lin et al, 2009). Some studies also reported the relationships between denitrifiers and physicochemical parameters, such as correlations of nirK and nirS genes abundance with pile temperature (Zhang et al, 2015), and correlations of narG , nirK and nosZ genes abundance with soil TOC (Kandeler et al, 2006; Zhou et al, 2011). …”

“…The CH 4 and N 2 O fluxes from manure composting have been studied extensively, contributing to a comprehensive assessment of CH 4 and N 2 O emissions from manure composting worldwide [Czepiel et al, 1996; Hao et al, 2001; Intergovernmental Panel on Climate Change (IPCC), 2006; Xu et al, 2007; Mulbry and Ahn, 2014; Jiang et al, 2015; Pardo et al, 2015]. Yet, little is known about the interaction between pile physicochemical parameters and bacterial community, which has a key role in CH 4 and N 2 O emissions from manure composting (Sharma et al, 2011; Angnes et al, 2013; Zhang et al, 2015). In particular, few studies have simultaneously focused on quantitative analysis of bacterial community composition and CH 4 and N 2 O fluxes from composting manure (Maeda et al, 2010a,b; Chen et al, 2014; Zhang et al, 2015).…”

“…Yet, little is known about the interaction between pile physicochemical parameters and bacterial community, which has a key role in CH 4 and N 2 O emissions from manure composting (Sharma et al, 2011; Angnes et al, 2013; Zhang et al, 2015). In particular, few studies have simultaneously focused on quantitative analysis of bacterial community composition and CH 4 and N 2 O fluxes from composting manure (Maeda et al, 2010a,b; Chen et al, 2014; Zhang et al, 2015). Comparative quantitative analysis of specific bacterial functional groups and their interplay in CH 4 and N 2 O emissions during manure composting are still limited.…”

Effects of Copper Addition on Copper Resistance, Antibiotic Resistance Genes, and intl1 during Swine Manure Composting

“…The pH then declined to 8.51 in the final compost. The increase in the pH during the initial stage of composting was due mainly to the release of ammonia and the degradation of organic acids (Li et al, 2014), whereas the decrease in the pH during the later phase was probably caused by the synthesis of phenolic compounds, or the nitrifying process (Zhang et al, 2015). In addition, the pH of Cu2000 was slightly lower than that of the control and Cu200 after 21 days, which may have been related to the adverse effects of Cu on the urease activity (Li et al, 2014), thereby inhibiting the release of ammonia.…”