Changes in dissolved organic matter composition and metabolic diversity of bacterial community during the degradation of organic matter in swine effluent

In this study, an incubation experiment was conducted with effluent collected from the concentrated swine-feeding operations (CSFOs) located in Yujiang County of Jiangxi Province, China. The purpose of this study was to elucidate the relationships between the composition of dissolved organic matter (DOM) and the community-level physiological profiles (CLPPs) of microorganisms in swine effluent. For all samples examined, the concentrations of dissolved organic carbon (DOC) and total dissolved nitrogen (TDN) were decreased by an average of 58.2 ± 30.4 and 49.2 ± 38.7 %, whereas total dissolved phosphorus (TDP) exhibited an average final accumulation of 141.5 ± 43.0 %. In the original samples, ammonium nitrogen accounted for 88.9 ± 4.9 % of the TDN, which was reduced to a final average of 83.9 ± 9.6 %. Two protein-like (tyrosine and tryptophan) and two humic-like (fulvic acids and humic acids) components were identified using a three-dimensional excitation-emission matrix. With the increase in incubation time, the relative concentrations of two protein-like components in effluent were reduced by an average of 83.2 ± 24.7 %. BIOLOG™ ECO plates were used to determine the metabolic fingerprint of the bacterial community, and a shift in the utilization patterns of substrates was observed over the study period. Additionally, the Shannon–Wiener index of CLPP was ultimately reduced by an average of 43.5 ± 8.5 %, corresponding to the metabolic diversity of the bacterial community. The redundancy analysis identified significant relationships between environmental parameters and the CLPP of microorganisms. To a certain degree, the DOM compositions were linked with the substrate utilization patterns of the bacterial community during the degradation of organic matter in swine effluent.