Bioproduction of Poly-β-hydroxybutyrate (PHB) Using Dairy Wastewater: A Sustainable and Greener Approach

Abstract

Escalating usage of non-degradable plastics is raising significant concern. The search for bio-based degradable alternatives commenced far back, and the burgeoning progress in the development of bioplastics is featured as a critical solution to ongoing plastic pollution. Bioplastics are becoming a promising substitute for petroleum-based plastics, depending on the production source and post-use disposal management. Among all the promising materials, microbially produced polyester and polyhydroxybutyrate (PHB) belong to the polyhydroxyalkanoate (PHA) family and are biocompatible and non-toxic. PHB has remarkable thermal and mechanical properties, making it a potential replacement for ubiquitous plastics. In this study, PHB-producing bacteria were isolated from mangrove soil and checked for PHB accumulation using preliminary and confirmatory staining. Out of a total 25 isolates, 13 were found positive for PHB accumulation. Dairy wastewater was used as a cultivation medium for PHB production; the potential PHB-producing strain was selected for morphological and biochemical characterization up to the genus level and was found to be Bacillus sp (3.6 ±0.15g/L). Extracted PHB was characterized using FTIR, XRD, and TGA; in FTIR, the characteristic peak was recorded at 1724 cm-1, and XRD showed the crystallinity of PHB. TGA curve displayed maximum mass loss between 254-290oC, indicating thermal stability. The outcome of the present study shows that dairy wastewater is an indispensable medium for PHB production in an eco-friendly way.