title: Microbial population dynamics and changes in main nutrients during the acidification process of pig manures.
abstract: This study evaluated the impact of pig manure acidification on anaerobic treatment and composition of the fecal microbial community. According to the different chemical oxygen demand (COD) in the anaerobic treatment processes, pig manure was diluted 4 times (x4), 16 times (x16), or 64 times (x64) and subjected to acidification. During the acidification process, pH, soluble chemical oxygen demand (SCOD), volatile fatty acids (VFAs), nitrogen (N), phosphorus (P) and potassium (K) were determined along with microbial population dynamics. The pH of the three dilutions first declined, and then slowly increased. The total VFAs of x4 and x16 dilutions peaked on day 15 and 20, respectively. The content of acetic acid, propanoic acid, butanoic acid and valeric acid of the x4 dilution were 23.6, 11.4, 8.8 and 0.6 g/L respectively, and that of the x16 dilution was 5.6, 2.3, 0.9 and 0.2 g/L respectively. Only acetic acid was detected in the x64 dilution, and its level peaked on day 10. The results showed that the liquid pig manure was more suitable to enter the anaerobic methanogenic bioreactors after two weeks of acidification. During the acidification process, total P concentration increased during the first ten days, then dropped sharply, and rose again to a relatively high final concentration, while total N concentration rose initially and then declined. Based on the analysis of denaturing gradient gel electrophoresis (DGGE) and 16S rRNA gene clone library, we concluded that the acidification process reduced the number of pathogenic bacteria species in pig manure.
authors.affiliation: College of Agronomy and Biotechnology/Center of Biomass Engineering, China Agricultural University, Beijing 100193, China. zhangdonglucky@163.com
authors.forename: Dongdong
authors.initials: D
authors.lastname: Zhang
authors.forename: Xufeng
authors.initials: X
authors.lastname: Yuan
authors.forename: Peng
authors.initials: P
authors.lastname: Guo
authors.forename: Yali
authors.initials: Y
authors.lastname: Suo
authors.forename: Xiaofen
authors.initials: X
authors.lastname: Wang
authors.forename: Weidong
authors.initials: W
authors.lastname: Wang
authors.forename: Zongjun
authors.initials: Z
authors.lastname: Cui
mesh_terms: D000818:Animals; D001421:Bacteria, Anaerobic / Q000145:classification / Q000235:genetics / Q000378:metabolism* / Q000472:pathogenicity; D005232:Fatty Acids, Volatile / Q000737:chemistry / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D008372:Manure / Q000032:analysis* / Q000382:microbiology*; D010802:Phylogeny; D011157:Population Dynamics; D012336:RNA, Ribosomal, 16S / Q000032:analysis; D013552:Swine; D014835:Volatilization
chemical_list: D005232:Fatty Acids, Volatile; D008372:Manure; D012336:RNA, Ribosomal, 16S