Acetateutilizers

Acetateutilizers are organisms that rely on acetate as a carbon and energy source, either exclusively or in combination with other substrates. They include bacteria, archaea, fungi, and some microeukaryotes and are found in environments where acetate is produced or accumulates, such as soils, freshwater and marine systems, anaerobic digesters, and the guts of ruminants and insects.

Metabolism typically begins with activation of acetate to acetyl‑CoA by acetyl‑CoA synthetase (Acs). The acetyl‑CoA then feeds central metabolism, either through the tricarboxylic acid cycle for energy or, when biosynthesis is needed, through the glyoxylate cycle, which conserves carbon skeletons. The glyoxylate shunt uses isocitrate lyase (aceA) and malate synthase (aceB) to bypass the CO2‑releasing steps. In some organisms, the phosphotransacetylase/acetate kinase (Pta/AckA) system can operate in the reverse direction to balance energy and redox status, particularly under fermentative conditions.

Ecology and regulation: Acetate utilizers occupy niches where acetate is produced by fermentation or enters as a metabolic by‑product. Their activity affects carbon flux in soils, sediments, and bioreactors. Expression of ACS and glyoxylate cycle enzymes is influenced by carbon source, oxygen availability, and nitrogen status, and by regulatory networks that mediate carbon catabolite repression.

Applications and open questions: Studying acetate utilizers aids understanding of carbon cycling and informs biotechnologies that exploit acetate as a feedstock or by‑product. Key questions concern the diversity of acetate‑activating enzymes, when the glyoxylate cycle is used, and how microbial communities coordinate acetate turnover.