Characterization, Biosynthesis, and Regulation of Granulose in Clostridium acetobutylicum

Abstract

Synthesis of granulose was investigated in 15 solvent-producing Clostridium strains. Only one of the strains did not produce granulose. The structure of granulose in Clostridium acetobutylicum P262 consisted of a high-molecular-weight polyglucan containing only (1-4) linked D-glucopyranose units. Biosynthesis of granulose in C. acetobutylicum P262 was dependent on ADPglucose pyrophosphorylase, and granulose synthase and mutants defective in granulose accumulation lacked either one or both enzyme activities. Granulosepositive revertants exhibited both enzyme activities. ADPglucose pyrophosphorylase and granulose synthase were not subject to allosteric control by metabolites. Granulose accumulation and the biosynthetic enzyme activities were initiated immediately before the pH breakpoint and were detected in cells only at the end of the exponential growth phase. Granulose accumulation did not occur under conditions of nitrogen limitation, excess carbon, or excess energy. The accumulation of glycogen-like reserve polymers is widespread among bacteria and usually occurs under conditions in which growth is limited in the presence of an excess carbon and energy source (9, 28). Glycogen biosynthesis occurs via the ADPglucose pathway in bacteria (28). The key enzymes involved in glycogen synthesis are ADPglucose pyrophosphorylase (EC 2.7.7.27) and glycogen (granulose) synthase (EC 2.4.1.21) which catalyze the following reactions:

A comparative and functional genomics analysis of the genusRomboutsiaprovides insight into adaptation to an intestinal lifestyle

“…This is also true for R. lituseburensis A25K T in which electron translucent bodies are visible in TEM pictures (Fig. 1), similar to the carbohydrate or polyhydroxybutyrate inclusions observed in for example Clostridium pasteurianum (111), C. acetobutylicum (112) and C. botulinum (113). The development of these inclusion bodies appears to coincide with the initiation of sporulation.…”

Stability of solvent production by Clostridium acetobutylicum in continuous culture: strain differences

“…It was most significant therefore that the acidogenic (Spo-Gran-S O W ) mutants were capable of spontaneous reversion at a measurable frequency to Spof Gran' S o h + , indicating that the loss of all three traits (with possibly others also) had been the pleiotropic consequence of a single mutational event. The chemostat-selected acidogenic mutants of NCIB 8052/SBA52 were thus similar to the cls mutants of P262 (Long et al 1984;Reysenbach et al 1986) and possibly also to the acidogenic Spo-mutants of strain NRRL B643, e.g. mutant 6A, isolated by Rogers & Palosaari (1987).…”

Acetone-butanol fermentation revisited.

“…The initial acidogenic phase of the fermentation is normally characterized by the presence of highly motile dividing rods. However, a few hours before the pH breakpoint is reached, motility begins to decrease and the cell begins to accumulate granulose (a glycogenlike storage product) (110,147,216). The shift to solvent production is characterized by the conversion of the vegetative rods into swollen phase-bright clostrial forms and is accompanied by the production of an extracellular capsule or slime layer (110).…”