Polyhydroxybutrate Production Using Groundnut Shell as Substrate by Bacillus circulans (MTCC 8167)

Abstract

Groundnut shell is considered to agro-industrial waste product and is rich in lignocellulose materials. It is obtained after the removal of groundnut seed from its pod and used as fodder for cattle. Duc et al., (2019) elaborately reviewed beneficial uses groundnut shells for commercial and industrial purposes and listed production of various bio-products such as biodiesel, bioethanol, and nano-sheet. The aim of this work was to study the production of polyhydroxy butyrate (PHB) using groundnut shells as the carbon source after hydrolysate. Groundnut shell was pre-treated with alkaline reagent with 0.5M, 1M, and 1.5M, of potassium hydroxide and acid hydrolysis with 30%, 50%, and 70%, of sulphuric acid. Combined alkali (1M of potassium hydroxide) and acid (70% sulphuric acid) pre-treatment of groundnut shell yield maximum reducing sugar. In addition, with pre-treated groundnut shell, various pH level (6, 7, & 8), KH2PO4 (100mg/l, 200mg/l and 300mg/l), and temperature (250C, 300C and 350C) are also test for PHB production. Bacillus circulans (MTCC 8167) significantly utilized the hydrolysate substrate and produced the maximum amount PHB (7.6 ± 0.2 g L-l) with pH level 7 and 300C with 100mg/l of KH2PO4. A detailed study of the functional group was also done using FTIR and NMR. Through biochemical pre-treatment, an in-expensive groundnut shell was converted into a valuable bio-product in order to achieve the minimum waste production.