Evaluating the potential of pectin de-esterifying bacterial cultures for the production of methanol from fruit waste: Optimization of critical operational parameters

Abstract

Fruit wastes are a good source of pectin, which can be de-esterified into pectate and methanol by microbial pectinesterases. Methanol is an important fuel substance and thus, this study aimed at developing a scalable process for efficient biological conversion of fruit wastes into methanol. Pectin digesting bacteria were enriched, identified and the consortium was used for methanol production. Experiments were conducted in two phases, where, feasibility of methanol production using the enriched consortium was investigated in phase I and in phase II, the critical operational parameters such as substrate/inoculum (S/I) ratio, fraction of fruit waste, temperature and rpm were optimized. Initial reactor experimental study resulted in the production of 44.13 g/L methanol which was further optimized with respect to substrate fractionation, S/I ratio, temperature and rpm. Maximum methanol was obtained with whole blend fruit wastes as substrate with S/I ratio of 3 at 40 °C and 150 rpm. By further studying the pectin conversion efficiency of the microbe and efforts towards increasing it for higher methanol production this process can be scaled up or integrated into other biomass conversion processes for methanol as another product.