Open AccessPatterns of carbon flow from glucose to methane in a thermophilic anaerobic bioreactor
Author(s) -
Zinder Stephen H.
Publication year - 1986
Publication title -
fems microbiology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.899
H-Index - 151
eISSN - 1574-6968
pISSN - 0378-1097
DOI - 10.1111/j.1574-6968.1986.tb01734.x
Subject(s) - propionate , chemistry , butyrate , fermentation , bioreactor , anaerobic exercise , formate , mixed acid fermentation , incubation , biochemistry , ethanol , methanogenesis , biohydrogen , thermophile , chromatography , food science , methane , hydrogen , hydrogen production , bacteria , lactic acid fermentation , biology , organic chemistry , lactic acid , enzyme , physiology , genetics , catalysis
[U‐ 14 C]Glucose, added carrier‐free to sludge from a thermophilic anaerobic bioreactor being fed a lignocellulose waste, was rapidly turned over with less than one‐third of the original radiolabel remaining as glucose after 5 s of incubation. The primary labeled products found were [ 14 C]acetate and 14 CO 2 , which were in a ratio near 2:1. Further incubation resulted in the disappearance of [ 14 C]acetate and the appearance of an equivalent amount of label as 14 CH 4 and 14 CO 2 . No significant production of [ 14 C]propionate, butyrate, lactate, or ethanol was detected from [ 14 C]glucose, even if these potential intermediates (unlabeled) were added to the sludge at a concentration of 1 mM to trap any label entering their pools. Addition of 0.8 atm (80 kPa) of H 2 to the headspace over sludge resulted in some accumulation of [ 14 C]lactate and a corresponding decrease in [ 14 C]acetate produced from [ 14 C]glucose. Production of [ 14 C]propionate, butyrate and ethanol were still not significant in the presence of H 2 . Incubation of sludge for 1 h in the presence of hydrogen resulted in increases in the lactate and formate concentrations, but not those of propionate, butyrate, or ethanol. These results demonstrate that glucose was metabolized directly to acetate, CO 2 , and H 2 by the microbial populations in the bioreactor with little carbon from glucose flowing through other intermediates, indicating a high degree of coupling between glucose fermentation and hydrogen uptake. The short‐term response of these microbial populations to elevated H 2 partial pressures was to increase lactate production.