PNNL

Abstract

Efficient recovery and reuse of solvents used for thermochemical deconstruction of lignocellulosic biomass is critical to reducing operational costs, minimizing waste generation, and ensuring the economic feasibility of biorefineries. The use of alkylamines with low boiling points, like butylamine have the potential to serve as effective biomass pretreatment solvents; however, their effects on the microbial conversion of sugars present in hydrolysates to biofuels and bioproducts need to be investigated. Here we employed butylamine to pretreat hybrid poplar biomass and characterize its effects on the release of fermentable sugars after solvent removal and enzymatic hydrolysis, as well as the biocompatibility of the produced hydrolysates with three organisms commonly used as bioconversion hosts. We observed that residual butylamine and the derivative butylacetamide were present in high enough concentrations in the hydrolysates to exert toxicity to strains of Aspergillus niger, Pseudomonas putida and Rhodosporidium toruloides that produce malic acid, isoprenol and bisabolene, respectively. Removal of the toxic compounds by charcoal filtration and the supplementation of different nutrients to the hydrolysates enabled strong growth and high levels of substrate consumption and bioproduct accumulation from the three engineered organisms. These results highlight the effectiveness of a butylamine deconstruction method for the conversion of poplar biomass, allowing for >93% solvent removal and the generation of a nutrient-rich hydrolysate containing >100 g/L of sugars that is capable of supporting diverse microbial conversion platforms.