A new biological recovery approach for PHA using mealworm, Tenebrio molitor

- Freeze-dried cells containing PHA granules can be fed to mealworms.
- Mealworms partly digest the cells but not the PHA granules.
- Partially purified intact PHA granules are excreted in the form of fecal pellet.
- The PHA granules can be further purified by water and detergent.
- The properties of PHA granules were similar to chloroform extracted PHA.

Bacterial polyhydroxyalkanoates (PHA) are expensive partly due to the recovery and purification processes. Thus, many studies have been carried out in order to minimize the cost. Here we report on the use of mealworm, which is the larva of mealworm beetle (Tenebrio molitor) to recover PHA granules from Cupriavidus necator. Mealworms were shown to readily consume the freeze-dried C. necator cells and excrete the PHA granules in the form of whitish feces. Further purification using water, detergent and heat resulted in almost 100% pure PHA granules. Comparison with chloroform extraction showed no signs of reduction in the molecular weight and dispersion of the PHA molecules. Scanning electron microscopy and dynamic light scattering measurements revealed that the biologically recovered PHA granules retained their native spherical morphology. The PHA granules were subjected to a battery of tests to determine their purity and properties in comparison to the chloroform extracted PHA. This study has demonstrated the possibility of using mealworms as a biological agent to partially purify the PHA granules.