Metabolism of Formate inMethanobacterium formicicum

Abstract

Methanobacterium formicicum strain JF-1 was cultured with formate as the sole energy source in a pH-stat fermentor. Growth was exponential, and both methane production and formate consumption were linear functions of the growth rate. Hydrogen was produced in only trace amounts, and the dissolved H 2 concentration of the culture medium was below 1 μM. The effect of temperature or pH on the rate of methane formation was studied with a single fermentor culture in mid-log phase that was grown with formate under standard conditions at 37°C and pH 7.6. Methane formation from formate occurred over the pH range from 6.5 to 8.6, with a maximum at pH 8.0. The maximum temperature of methanogenesis was 56°C. H 2 production increased at higher temperatures. Hydrogen and formate were consumed throughout growth when both were present in saturating concentrations. The molar growth yields were 1.2 ± 0.06 g (dry weight) per mol of formate and 4.8 ± 0.24 g (dry weight) per mol of methane. Characteristics were compared for cultures grown with either formate or H 2 -CO 2 as the sole energy source at 37°C and pH 7.6; the molar growth yield for methane of formate cultures was 4.8 g (dry weight) per mol, and that of H 2 -CO 2 cultures was 3.5 g (dry weight) per mol. Both formate and H 2 -CO 2 cultures had low efficiencies of electron transport phosphorylation; formate-cultured cells had greater specific activities of coenzyme F 420 than did H 2 -CO 2 -grown cultures. Hydrogenase, formate dehydrogenase, chromophoric factor F 342 , and low levels of formyltetrahydrofolate synthetase were present in cells cultured with either substrate. Methyl viologen-dependent formate dehydrogenase was found in the soluble fraction from broken cells.

Investigation of hypothesized anaerobic stabilization mechanisms in biological nutrient removal systems

“…Average hydrogen and methane recoveries of, respectively, 86 and 88 percent were obtained with known standards. These compare favorably with the recovery reported by Schauer and Ferry (1980) for a more complicated dissolved hydrogen esti mation procedure.…”

Ulva lactuca is poorly fermented but alters bacterial metabolism in rats inoculated with human faecal flora from methane and non‐methane producers

“…In humans, methane production was associated with a slow gut transit time and a high intestinal pH (Stephen et al 1986). Moreover, methanogenic bacteria showed increased growth rates at alkaline pH values (Schauer and Ferry 1980). Therefore, in the HMP group, methane production may not be due to Ulva lactuca fermentation but to an indirect eþect of the caecal pH change.…”

Identification of molybdopterin guanine dinucleotide in formate dehydrogenase from Methanobacterium formicicum

“…In the experiments outlined below, the M. forrnicieum formate dehydrogenase pterin is identified as molybdopterin guanine dinucleotide. Thus, the molybdenum cofactor present in this enzyme is not unique to the archaebaeteria but rather is Methanobacterium forrnicicum was cultured and harvested as described previously [8]. Formate dehydrogenase was isolated [8] and stored frozen prior to cofactor characterization.…”

“…Thus, the molybdenum cofactor present in this enzyme is not unique to the archaebaeteria but rather is Methanobacterium forrnicicum was cultured and harvested as described previously [8]. Formate dehydrogenase was isolated [8] and stored frozen prior to cofactor characterization. The pterin cofactor was alkylated using iodoacetamide and released from the protein by incubation with SDS as described earlier [4].…”