Lignin to polyhydroxyalkanoate bioprocessing by novel strain of Pseudomonas monteilii

Abstract

A fed-batch process using lignin-rich black liquor, derived from alkaline pretreated sugarcane bagasse, as carbon source was optimized for the production of polyhydroxyalkanoate (PHA) by Pseudomonas monteilii. Different C:N ratio and pulse feeding schemes in batch and fed-batch processes were studied for their effects on lignin conversion efficiency to cell growth and PHA synthesis. Under optimized feeding profiles and overall C:N ratio of 0.18 g lignin:mg NH4Cl, 238 mg/L of PHA equivalent to 13% PHA content of the cell dry weight was achieved. This was enhanced by 1.9 folds compared to batch process under similar C:N ratio. The produced biopolymer composed of two dominant monomers, 3-hydroxybutyrate and 3-hydroxydecanoate, based on GC-MS analysis. Overall, this work demonstrates the effect of fed-batch fermentation parameters for the synthesis of PHA from waste black liquor, which could serve as a base to lead further investigation in developing integrated lignin bioprocessing platform for cost-effective sustainable biorefineries in Bio-Circular-Green economy.