Cyanobacteria possess a CO₂ concentrating mechanism that enables them to accumulate CO₂ from the environment. Cyanobacteria are able to fix CO₂ into carbohydrates.

Cyanobacteria vary considerably in their ability to consume organic carbon from their surroundings. Many strains are obligate photoautotrophs where the sole carbon source is CO₂, while others are able to perform photomixotrophic or even heterotrophic growth using a wide variety of organic substances. Cyanobacteria constitute a unique case where the anabolic and catabolic carbohydrate metabolisms function in the same cellular compartment. In addition, the photosynthetic and respiratory electron transport pathways share components in the thylakoid membranes. Despite its importance to our understanding of cyanobacterial metabolism, little is known about the mechanisms involved in the shifts between photoautotrophic, heterotrophic and photomixotrophic modes of growth, and their regulation; between the different pathways of carbohydrate breakdown—glycolysis, fermentation, the oxidative pentose phosphate, the Krebs cycle and the photorespiratory pathways. However recent advances have been made in our understanding of the CO₂ concentrating mechanism and carbon metabolism in cyanobacteria.

from Kaplan et al in The Cyanobacteria: Molecular Biology, Genomics and Evolution

Further reading:

1. The Cyanobacteria: Molecular Biology, Genomics and Evolution
2. Microbiology Books

Labels: carbon dioxide, cyanobacteria, environment, metabolism