Production of polyhydroxybutyrate (PHB) by a novel Klebsiella pneumoniae strain using low-cost media from fruit peel residues

Plastics are widely used for various applications. Once discarded, it is commonly known that they represent a high environmental threat due to their slow degradation; for this reason, there is an imminent need to replace these products with eco-friendlier ones. In the present work, four bacterial polyhydroxybutyrate (PHB) producers, two consortia, and two isolated strains were successfully recovered from the facilities of a paper-manufacturing industry. Spectroscopic studies of the biopolymers obtained from these bacteria corroborated their PHB production capabilities, ranging from 4.04 ± 0.16 to 23.82 ± 3.39 g/L. The characterization of the isolate that presented the highest production yield initially coded as E22 led to the identification of a Klebsiella pneumoniae strain, which, compared with other PHA bacterial producers reported to date, could be considered with high production potential. The strain E22 was grown in 5 different media prepared from fruit peel residues of banana, orange, papaya, watermelon, and melon, to determine its growth and PHA production capabilities in these low-cost media. The results obtained show different bacterial growth yields among the media tested, although PHB production yields and productivities were similar in all these low-cost media. Cellular accumulation of the biopolymer was higher in watermelon peel medium (8.4 × 10−10 g/CFU). These results reveal the potential of K. pneumoniae E22 for PHB production applications and establish encouraging alternatives to be broader explored regarding low-cost media that could enhance the scale-up of bacterial PHA production processes.