M. Fukui et al., In situ substrates for sulfidogens and methanogens in municipal anaerobic sewage digesters with different levels of sulfate, WATER RES, 34(5), 2000, pp. 1515-1524
To clarify the interaction between sulfidogens and methanogens in municipal
anaerobic digesters, in situ substrate utilization by the two microbial gr
oups was characterized by the accumulation rates of substrates after the ad
dition of specific inhibitors, 20 mM of molybdate for sulfidogens and 0.01%
(v/v) of chloroform for methanogens in three anaerobic sludge digesters wi
th different concentrations of sulfate (A, 1.2; B, 1.8; C, 2.7 mM). The rat
es. of sulfate reduction and methane production in sludge C were the highes
t and the lowest, respectively among the three sludges. The major substrate
s for methanogens were acetate (35-58%), and propionate (17-22%) in all the
sludges. Propionate should be utilized by methanogens after conversion to
acetate and H-2 by syntrophic hydrogen-producing acetogens, as no methanoge
ns are known to directly utilize propionate. Detectable accumulated substra
tes for sulfidogens (< 20%) were propionate in sludges A and B and acetate
in C. Still approximately 80% of substrates for sulfidogens were unknown. T
hese results show that acetate or propionate is a common substrate for sulf
idogens and methanogens but sulfidogens can mainly grow on the other substr
ates in the municipal anaerobic sludges, implying nutritional segregation b
etween sulfidogens and methanogens. (C) 2000 Elsevier Science Ltd. All righ
ts reserved.