Journal Article

Ammonia effect on hydrogenotrophic methanogens and syntrophic acetate-oxidizing bacteria

Angelidaki, Irini, Fotidis, Ioannis A., Wang, Han

2015

Overview

Ammonia-rich substrates can cause inhibition on anaerobic digestion process. Syntrophic acetate-oxidizing bacteria (SAOB) and hydrogenotrophic methanogens are important for the ammonia inhibitory mechanism on anaerobic digestion. The roles and interactions of SAOB and hydrogenotrophic methanogens to ammonia inhibition effect are still unclear. The aim of the current study was to determine the ammonia toxicity levels of various pure strains of SAOB and hydrogenotrophic methanogens. Moreover, ammonia toxicity on the syntrophic-cultivated strains of SAOB and hydrogenotrophic methanogens was tested. Thus, four hydrogenotrophic methanogens (i.e. Methanoculleus bourgensis, Methanobacterium congolense, Methanoculleu thermophilus and Methanothermobacter thermautotrophicus), two SAOB (i.e. Tepidanaerobacter acetatoxydans and Thermacetogenium phaeum) and their syntrophic cultivation were assessed under 0.26, 3, 5 and 7 g NH4+-N L−1. The results showed that some hydrogenotrophic methanogens were equally, or in some cases, more tolerant to high ammonia levels compared to SAOB. Furthermore, a mesophilic hydrogenotrophic methanogen was more sensitive to ammonia toxicity compared to thermophilic methanogens tested in the study, which is contradicting to the general belief that thermophilic methanogens are more vulnerable to high ammonia loads compared to mesophilic. This unexpected finding underlines the fact that the complete knowledge of ammonia inhibition effect on hydrogenotrophic methanogens is still absent. SAOB were more sensitive to high ammonia compared to the hydrogenotrophic methanogens tested. Thus, hydrogenotrophic methanogens could be equally, if not more, tolerant to high ammonia levels compared to SAOB.

• Publisher: Oxford University Press
• Subject: Acetates - metabolism / Acetic acid / Ammonia / Ammonia - metabolism / Anaerobic digestion / Anaerobic processes / Anaerobiosis / Analysis / Bacteria / Bacteriological Techniques / Biogas / Cultivation / Ecology / Identification and classification / Methane - metabolism / Methanobacteriaceae / Methanobacteriaceae - classification / Methanobacteriaceae - growth & development / Methanobacteriaceae - metabolism / Methanogenic bacteria / Methanomicrobiaceae - classification / Methanomicrobiaceae - growth & development / Methanomicrobiaceae - metabolism / Microbiology / Oxidation / Refuse as fuel / Strains (organisms) / Substrate inhibition / Thermophilic bacteria / Toxicity