Effect of operating temperature on anaerobic digestion of the Brazilian waterweed Egeria densa and its microbial community.
To develop an effective treatment for the globally invasive Brazilian waterweed Egeria densa, anaerobic digestion was observed at 37 °C, 55 °C, and 65 °C. The average methane production rate at 55 °C was 220 mL L-1day-1, which was two-fold that at 37 °C and 65 °C. Volatile fatty acid accumulation was detected under thermophilic conditions; however, although there was methane production, the system did not shutdown. The microbial communities differed between mesophilic (37 °C) and thermophilic (55 °C and 65 °C) conditions. A bacterial community consisting of the phyla Bacteroidetes (43%), Firmicutes (37%), Proteobacteria (9%), Synergistetes (5%), Spirochaetes (1%), and unclassified bacteria (5%) were detected under mesophilic condition. In contrast, the phylum Firmicutes was dominant under thermophilic conditions. In the archaeal community, Methanosaeta concilii (40%), Methanolinea sp. (17%), and unclassified euryarchaeota (43%) were detected under mesophilic condition. Methanosarcina thermophila (87% at 55 °C, 54% at 65 °C) and Methanothermobacter thermautotrophicus (13% at 55 °C, 46% at 65 °C) were detected under thermophilic conditions. At both 37 °C and 55 °C, acetoclastic methanogenesis likely occurred because of the lower abundance of hydrogenotrophic methanogens. At 65 °C, the growth of the acetoclastic methanogen Methanosarcina thermophila was limited by the high temperature, therefore, acetate oxidation and hydrogenotrophic methanogenesis may have occurred.
Faculty of Science and Engineering, Soka University, 1-236 Tangi-machi, Hachioji, Tokyo 192-8577, Japan. Electronic address: kewatana@soka.ac.jp.
Keiko
K
Watanabe
School of Environment and Society, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8550, Japan.
Mitsuhiko
M
Koyama
Faculty of Science and Engineering, Soka University, 1-236 Tangi-machi, Hachioji, Tokyo 192-8577, Japan.
Junko
J
Ueda
School of Environmental Science, University of Shiga Prefecture, 2005 Hassaka-cho, Hikone, Shiga 522-8533, Japan.
Syuhei
S
Ban
Graduate School of Engineering, Soka University, 1-236 Tangi-machi, Hachioji, Tokyo 192-8577, Japan.
Norio
N
Kurosawa
Graduate School of Engineering, Soka University, 1-236 Tangi-machi, Hachioji, Tokyo 192-8577, Japan.
Tatsuki
T
Toda
D000693:Anaerobiosis; D001105:Archaea / Q000145:classification* / Q000302:isolation & purification / Q000378:metabolism*; D001421:Bacteria, Anaerobic / Q000145:classification* / Q000302:isolation & purification / Q000378:metabolism*; D001938:Brazil; D005232:Fatty Acids, Volatile / Q000378:metabolism; D005285:Fermentation; D031321:Hydrocharitaceae / Q000378:metabolism* / Q000382:microbiology*; D008697:Methane / Q000378:metabolism; D013696:Temperature
D005232:Fatty Acids, Volatile; D008697:Methane
Anaerobic digestion; Brazilian waterweed; Microbial community; Temperature