Biohydrogen Production from Food Waste Using Glucose-Adapted Hyperthermophilic Archaeon

Abstract

PurposeGlucose is one of the most important carbon and energy source for heterotrophic growth in all living organisms. However, glucose has been reported as a poor substrate to support the growth of hyperthermophilic archaea belonging to the order Thermococcales. To enhance glucose-assisted growth of Thermococcus onnurineus NA1, adaptive evolution process was applied. In an effort for industrial applications, glucose-adapted cells were further tested for H2 producing potential using food processing waste as a promising zero-value substrate containing polysaccharides composed of glucose.MethodsAdaptive evolution of T. onnurineus NA1 was performed by transferring cells to fresh medium containing glucose until cell growth increased. Genome sequencing was conducted to identify genetic changes in adapted cells. H2 production in the parent strain and glucose-adapted cells was analyzed using either glucose or potato peel waste as substrate.ResultsThe glucose-adapted cells, WG-100T, had 10.8-fold and 14.7-fold increases in cell density and glucose consumption, respectively, compared to the parent strain. Genome sequencing of WG-100T revealed a total of 17 genomic changes in genes, including those encoding transcription factors and several proteins involved in various transport systems. WG-100T produced H2 using potato peel waste through simultaneous saccharification and fermentation.ConclusionThis study showed that the performance of the Thermococcales strain was improved by adaptive evolution, resulting in faster use of glucose. In addition, it was shown that the use of a hyperthermophile made it possible to produce biohydrogen without pretreatment of food processing waste for saccharification.Graphical