Regulation of Carbohydrate Utilization in Clostridium pasteurianum

Abstract

Clostridium pasteurianum is capable of fermentative growth on a number of carbohydrate compounds. Several, including glucose, fructose and sorbitol, are accumulated via a phosphoenolpyruvate-dependent phosphotransferase system (PTS), while the uptake of galactose and gluconate is protonmotive-force-dependent. We have examined the utilization of these substrates by cultures of C. pasteurianum growing on carbohydrate mixtures to determine whether the organism displays preferences for one carbon source over the others; such a preference may indicate the operation of specific mechanisms for regulation of carbohydrate metabolism. In most cases the carbohydrates were co-metabolized. Glucose was utilized together with fructose, gluconate and galactose, although galactose appeared to be favoured over glucose. This preference was not due to repression of synthesis of the glucose PTS. On the other hand, glucose prevented induction of the sorbitol PTS, and led to strong inhibition of sorbitol utilization in uninduced cells. Pre-adaptation of cells to growth on sorbitol counteracted the inhibition by glucose resulting in utilization of glucose and sorbitol at approximately equal rates.

Studies on the physiology and ecology of black-pigmented Gram-negative anaerobes which may be important in disease development

“…Much of our understanding of microbial energy conservation in anaerobic bacteria emanates from the pioneering work on clostridia during the last 30 years [1][2][3][4]. Generally, anaerobic fermentation can be represented diagrammatically as shown in Fig.…”

Lactate and ethanol dehydrogenase activities in continuous cultures of Clostridium thermosaccharolyticum LMG 6564

“…Indeed, during the last two decades, research on the fermentation metabolism of Clostridium kluyveri (Hillmer & Gottschalk, 1972, 1974Lurz et al, 1979), Clostridium pasteurianum and/or Clostridium butyricum (e.g. Jungermann et al, 1973;Petitdemange et al, 1976;Mitchell et al, 1987), and certainly Clostridium acetobutylicum (see, for example, Jones & Woods, Freier & Gottschalk, 1987;Wiesenborn et al, 1989a Rao & Mutharasan, 1989), has been encouraged, because of the importance of some of these organisms for the production of solvents (ethanol, butanol and acetone) or fuels (hydrogen gas and ethanol).…”

Genome-directed analysis of prophage excision, host defence systems, and central fermentative metabolism in Clostridium pasteurianum

“…Substrates that are metabolized at a reduced rate include arabinose, galactose, lactose, starch, and xylose. C. pasteurianum genes encoding putative phosphotransferase system (PTS) components could be identified for most of these fermentable substrates 109 110 , while galactose and gluconate have been shown to be taken up using a proton motive force (PMF) 111 . Owing to the immense substrate range exhibited by C. pasteurianum , product distribution varies dramatically and is dictated foremost by the degree of reductance of the substrate 112 .…”