Metabolic Networks in Clostridium acetobutylicum: Interaction of Sporulation, Solventogenesis, and Toxin Formation
from: Clostridia: Molecular Biology in the Post-genomic Era (Edited by: Holger Brüggemann and Gerhard Gottschalk). Caister Academic Press, U.K. (2009)
Clostridia belong to the few bacterial genera, able to undergo cell differentiation. They can either grow vegetatively or form endospores, the most resistant survival form of all living organisms. Some species, e. g. Clostridium acetobutylicum, link the metabolic network of sporulation to that of solventogenesis (formation of acetone and butanol). This gives them an ecological advantage by preventing toxic effects of acidic end products from the fermentation and allows them to stay longer metabolically active. In other clostridia, even toxin formation is coupled to sporulation. The key component for these links at the molecular level is the response regulator Spo0A in its phosphorylated form. In contrast to bacilli, clostridia do not possess a phosphorelay for Spo0A activation. Instead, phosphorylation is catalyzed directly by still unknown kinases or by butyryl phosphate. In addition to Spo0A~P, various other regulators are required to control the different metabolic networks. Systems biology is a new approach to understand these processes and their interaction at the molecular level and to adapt them for biotechnological use.