title: Semi-continuous anaerobic digestion for biogas production: influence of ammonium acetate supplement and structure of the microbial community.
abstract: BACKGROUND
  As an efficient disposal method of food waste, anaerobic digestion (AD) for biogas production is widely used. In order to understand the enhanced efficiency and stability of AD by appropriate amounts of ammonia and volatile fatty acids (NH4 (+)/VFAs), the characteristics of the corresponding microbial community with ammonium acetate supplement were investigated by denatured gradient gel electrophoresis (DGGE) and pyrosequencing analyses of samples, with or without supplement of NH4 (+)/VFAs.
  
  
  RESULTS
  In this study, four different supplement strategies of adding ammonium acetate were investigated, including a blank group (without supplement of ammonium acetate), a low group (L group, 0.7 g/L/d), a moderate group (M group, 1.0 g/L/d) and a high group (H group, 1.3 g/L/d), respectively. The average daily gas production was 1,839 mL/d, 1,655 mL/d, 1,448 mL/d and 1,488 mL/d for L, M, H and blank groups, respectively. The results reveal that the absence or overload of NH4 (+)/VFAs leads to the inhibition or failure of the AD operation. The blank and H groups were selected for further investigation of the microbial community by DGGE and pyrosequencing analyses. A significant difference of the microbial communities at different AD stages was observed between the blank and H groups.
  
  
  CONCLUSIONS
  Ammonium acetate, as an efficient supplement, significantly influences the characteristics of a semi-continuous AD operation. The DGGE and pyrosequencing analyses indicated that the different bacterial and archaeal communities occurred in the blank and H groups at different AD stages. Thus, an appropriate ammonium acetate supplement may maintain the balance of the microbial community and could be applied to adjust the AD operation and microbial composition towards optimal biogas production.
authors.affiliation: Beijing Key Laboratory of Bioprocess, Beijing University of Chemical Technology, No.15, Beisanhuan East Road, Beijing, 100029 People's Republic of China.
authors.forename: Haijia
authors.initials: H
authors.lastname: Su
authors.affiliation: Beijing Key Laboratory of Bioprocess, Beijing University of Chemical Technology, No.15, Beisanhuan East Road, Beijing, 100029 People's Republic of China.
authors.forename: Luo
authors.initials: L
authors.lastname: Liu
authors.affiliation: Beijing Key Laboratory of Bioprocess, Beijing University of Chemical Technology, No.15, Beisanhuan East Road, Beijing, 100029 People's Republic of China.
authors.forename: Shaojie
authors.initials: S
authors.lastname: Wang
authors.affiliation: Beijing Key Laboratory of Bioprocess, Beijing University of Chemical Technology, No.15, Beisanhuan East Road, Beijing, 100029 People's Republic of China.
authors.forename: Qingfeng
authors.initials: Q
authors.lastname: Wang
authors.affiliation: Beijing Key Laboratory of Bioprocess, Beijing University of Chemical Technology, No.15, Beisanhuan East Road, Beijing, 100029 People's Republic of China.
authors.forename: Yixin
authors.initials: Y
authors.lastname: Jiang
authors.affiliation: Beijing Key Laboratory of Bioprocess, Beijing University of Chemical Technology, No.15, Beisanhuan East Road, Beijing, 100029 People's Republic of China.
authors.forename: Xiaocong
authors.initials: X
authors.lastname: Hou
authors.affiliation: Beijing Key Laboratory of Bioprocess, Beijing University of Chemical Technology, No.15, Beisanhuan East Road, Beijing, 100029 People's Republic of China.
authors.forename: Tianwei
authors.initials: T
authors.lastname: Tan
keywords: Ammonium acetate; Anaerobic digestion; Biogas production; Glucose; Microbial community