Fundamentals of Microbiology

3.2.3 Bacterial Photosynthesis

Photosynthesis

Essentially, photosynthesis is the conversion of light energy from the sun into chemical energy. The chemical energy is then used to convert CO₂ from the atmosphere to more reduced carbon compounds, primarily sugars.

Cyanobacteria, algae, and green plants all contribute to this vital recycling with photosyntehsis.

Photosynthesis can be summarized as follows:

6CO₂ + 12 H₂O + Light energy —> C₆H₁₂O₆ +6O₂ + 6H₂O

Photosynthesis takes place in two stages. In the first stage, called the light reactions, light energy is used in a process that converts ADP and P to ATP. In additions, in the predominant form of the light reactions, the electron carrier NADP is reduced to NADPH. The coenzyme NADPH, like NADH, is an energy-rich carrier of electrons. In the second stage, called the dark (light-independent) reactions, these electrons are used along with energy from ATP to reduce CO₂ to sugar.