Production of Polyhydroxyalkanoates by Bacteria Isolated from the Gut of the Larvae of African Palm Weevil (Rhynchophorus phoenicis)

Abstract

The indispensability of plastics in everyday life has made the search for environmentally sustainable alternatives to these nonbiodegradable polymers more earnest. Polyhydroxyalkanoates (PHAs) are a class of biodegradable, biocompatible plastics comprising of polyesters of R-hydroxyalkanoic acids. They are accumulated intracellularly as polymeric granules upon cultivating several gram-positive and gram-negative bacteria in nutrient-limiting conditions. Hence, the objective of this paper is to investigate the production of polyhydroxyalkanoates by bacteria isolated from the gut of the larvae of African Palm Weevil (Rhynchophorus phoenicis) using agricultural-waste substrates. Two bacteria isolated from the gut of polystyrene-fed R. phoenicis larvae were utilized for the production of PHA using brewery waste, bean hull, cassava peel and palm pith, as substrates. The bacteria were identified as Lysinibacillus macriodes and Pantoea dispersa. Isolate P. dispersa accumulated PHAs ranging from 0.89- 1.44 g/L from agricultural waste and 4.24 g/L from glucose, equivalent to 30.8%-46.7% and 71.9% yields respectively. L. macrolides, accumulated PHAs ranging from 1.11-1.50 g/L from agricultural waste and 3.89 g/L from glucose equivalent to 40.4%-48.1% and 69.2% yields respectively. The isolates can be desirable candidates for PHAs production under optimized conditions.