Polyhydroxyalkanoates (PHA) production in bacterial co-culture using glucose and volatile fatty acids as carbon source.

Mixed bacterial cultures are increasingly being used in the production of polyhydroxyalkanoates (PHAs), as they have the potential to be more cost effective than axenic pure cultures. The purpose of this study was to use pure cultures in combination to identify their potential of PHA production. In this work we used volatile fatty acids (VFAs) and glucose as carbon source to check the ability of selected strains ST2 (Pseudomonas sp.) and CS8 (Bacillus sp.) as co-culture. The production of PHA in pure co-cultures of bacteria was therefore investigated in order to understand the effect of combining cultures on PHA production parameters and material properties. Bacteria could use the feed in better way when mixed as compared to individual strain. In undertaking this analysis, model volatile fatty acids (i.e., acetic and propionic acids) were used alone and in combination with glucose as feedstock. The production by Pseudomonas was 34% while 24% by Bacillus. However when combined and mixed feed (glucose + propionic acid) was used, 35% PHA produced. Overall, it was found that the ability of the pure cultures to produce PHA was low but when selected cultures were mixed, their ability to produce PHA was enhanced. Copolymers were obtained instead of homopolymers with improved properties. This suggests that industrial wastewater rich in volatile fatty acids and carbohydrates can be a good carbon source for PHA production with variable properties.