Promoting microbial utilization of phenolic substrates from bio-oil

Kirsten Davis, Iowa State University
Marjorie R. Rover, Iowa State University
Davinia Salvachúa, National Renewable Energy Laboratory
Ryan G. Smith, Iowa State University
Gregg T. Beckham, National Renewable Energy Laboratory
Zhiyou Wen, Iowa State University
Robert C. Brown, Iowa State University
Laura R. Jarboe, Iowa State University

This article is published as Davis, Kirsten, Marjorie R. Rover, Davinia Salvachúa, Ryan G. Smith, Gregg T. Beckham, Zhiyou Wen, Robert C. Brown, and Laura R. Jarboe. "Promoting microbial utilization of phenolic substrates from bio-oil." Journal of Industrial Microbiology and Biotechnology 46, no. 11 (2019): 1531-1545. DOI: 10.1007/s10295-019-02208-z.

Abstract

The economic viability of the biorefinery concept is limited by the valorization of lignin. One possible method of lignin valorization is biological upgrading with aromatic-catabolic microbes. In conjunction, lignin monomers can be produced by fast pyrolysis and fractionation. However, biological upgrading of these lignin monomers is limited by low water solubility. Here, we address the problem of low water solubility with an emulsifier blend containing approximately 70 wt% Tween® 20 and 30 wt% Span® 80. Pseudomonas putida KT2440 grew to an optical density (OD600) of 1.0 ± 0.2 when supplied with 1.6 wt% emulsified phenolic monomer-rich product produced by fast pyrolysis of red oak using an emulsifier dose of 0.076 ± 0.002 g emulsifier blend per g of phenolic monomer-rich product. This approach partially mitigated the toxicity of the model phenolic monomer p-coumarate to the microbe, but not benzoate or vanillin. This study provides a proof of concept that processing of biomass-derived phenolics to increase aqueous availability can enhance microbial utilization.