Measurement of Monosaccharides and Conversion of Glucose to Acetate in Anoxic Rice Field Soil

Abstract

Degradation of glucose has been implicated in acetate production in rice field soil, but the abundance of glucose, the temporal change of glucose turnover, and the relationship between glucose and acetate catabolism are not well understood. We therefore measured the pool sizes of glucose and acetate in rice field soil and investigated the turnover of [U-14C]glucose and [2-14C]acetate. Acetate accumulated up to about 2 mM during days 5 to 10 after flooding of the soil. Subsequently, methanogenesis started and the acetate concentration decreased to about 100 to 200 μM. Glucose always made up >50% of the total monosaccharides detected. Glucose concentrations decreased during the first 10 days from 90 μM initially to about 3 μM after 40 days of incubation. With the exception at day 0 when glucose consumption was slow, the glucose turnover time was in the range of minutes, while the acetate turnover time was in the range of hours. Anaerobic degradation of [U-14C]glucose released [14C]acetate and14CO2 as the main products, with [14C]acetate being released faster than14CO2. The products of [2-14C]acetate metabolism, on the other hand, were14CO2 during the reduction phase of soil incubation (days 0 to 15) and 14CH4 during the methanogenic phase (after day 15). Except during the accumulation period of acetate (days 5 to 10), approximately 50 to 80% of the acetate consumed was produced from glucose catabolism. However, during the accumulation period of acetate, the rate of acetate production from glucose greatly exceeded that of acetate consumption. Under steady-state conditions, up to 67% of the CH4 was produced from acetate, of which up to 56% was produced from glucose degradation.

Response of the methanogenic microbial community of a profundal lake sediment (Lake Kinneret, Israel) to algal deposition

“…At this time acetate was probably produced by fermentation of easily accessible DOM, and production was not yet balanced by consumption; that is, acetate was formed more rapidly than it was consumed by methanogenic archaea. Similar results were observed during the initial stage of anaerobic degradation of rice straw in a flooded rice field soil (Chidthaisong et al 1999). Actually, only minor amounts of CH 4 had been produced until day 2 ( Fig.…”

Acetate cycling in the water column of the Cariaco Basin: Seasonal and vertical variability and implication for carbon cycling

“…The maxima may mean that acetate production exceeds acetate consumption at some times, resulting in an accumulation of acetate. In anoxic sedimentary environments, transient acetate accumulations have been widely reported (Sansone and Martens 1982;Alperin et al 1994;Shannon and White 1996;Albert and Martens 1997;Chidthaisong et al 1999). The concentration elevation appears to be due to abrupt changes in biological activity because of changes in temperature, changes in the supply of available electron acceptors (e.g., sulfate), changes in the supply of labile organic carbon, or shifts in methanogen population.…”

Trophic interactions in the methanogenic microbial community of low-temperature terrestrial ecosystems

“…The investigation of microbial communities basically includes the study of the community as a whole operating under as close to the in situ conditions as possible and the study of the constituent functional groups of microorganisms as interacting components under condition of a deliberate imbalance of the community. The former mainly involves using different radioactive tracers as the immediate methanogenic precursors that can be incorporated into CH 4 [6,7] as well as isotopic fractionation during methanogenesis [8] under steady state conditions. The latter can be achieved by diluting the system and/or introducing the specific substrates of key microorganisms and metabolic inhibitors into the community [9,10].…”