PHAs are produced by a wide range of bacteria, including both Gram-positive and Gram-negative species. Some of the most well-studied PHA-producing bacteria include:

Cupriavidus necator: This bacterium is often used in research on PHA production due to its ability to produce large quantities of PHA from a variety of carbon sources.

Pseudomonas putida: This bacterium is known for its ability to produce PHAs from waste materials like glycerol, a byproduct of biodiesel production.

Bacillus megaterium: This bacterium is able to produce a variety of different types of PHAs, including both short-chain and long-chain polymers.

Azotobacter vinelandii: This bacterium is able to produce PHAs from nitrogen gas, making it a potential source of PHAs that do not rely on traditional carbon-based feedstocks.

The production of PHAs by these bacteria typically occurs under conditions of nutrient limitation, such as when a carbon source is present but other nutrients are limited. This stimulates the bacteria to produce PHAs as a form of energy storage. Researchers are working to optimize the conditions for PHA production by these bacteria in order to improve the efficiency and cost-effectiveness of PHA production.