6-27 : Inhibition of Growth of Zymomonas mobilis By Model Compounds Found in Lignocellulosic Hydrolysates

Fermentation performance in lignocellulosic hydrolysates is substantially inhibited by the presence of toxic compounds which can be formed during pretreatment.  The dilute acid pretreatment process gives rise to organic acids, primarily acetic acid, sugar degradation products such as furfural and hydroxymethylfurfural (HMF), phenolics from lignin degradation as well as inorganic salts mainly arising from the pretreatment and conditioning processes.  Using a quantitative high-throughput growth assay, a survey of toxicity of the various potential inhibitors including aldehydes, alcohols, organic acids and inorganics was conducted.  We will present detailed inhibitory kinetic data on the effect of these compounds, individually and in combination, on growth of Zymomonas mobilis.  Using this method, we have established a toxicity database for various compounds tested and have begun to prioritize inhibitors based on their relative importance to overall toxicity in hydrolysates for microorganisms.