Background: The critical issue in the competitiveness between bioengineering and chemical engineering is the products titer and the volume productivity. The most direct and effective approach usually employs high-density biocatalyst, while the weakened mass transfer and evoked foam problem accompany ultrahigh-density biocatalyst loading and substrate/product titer. In high-density obligate aerobic bioconversion, oxygen as electron acceptor is a speed-limiting step in bioprocesses, but sufficient oxygen supply will lead to the foaming which results in a significant reduction in oxygen utilization and the use of additional defoamers. In this study, we designed a novel sealed-oxygen supply (SOS) biotechnology to resolve the formidable barrier of oxygen transferring rate (OTR), for bio-based fuels and chemical production process. Results: Based on systemic analysis of whole-cell catalysis in Gluconobacter oxydans, a novel sealed-oxygen supply technology was smartly designed and experimentally performed for biocatalytic oxidation of alcohols, sugars and so on. By a simple operation skill of automatic online supply of oxygen in a sealed stirring tank bioreactor of SOS, OTR barrier and foaming problem was resolved with great ease. We finally obtained ultrahigh-titer products of xylonic acid (XA), 3-hydroxypropionic acid (3-HPA), and erythrulose at 588.4 g/L, 69.4 g/L, and 364.7 g/L, respectively. Moreover, the volume productivity of three chemical products was improved by 150-250% compared with normal biotechnology. This SOS technology provides a promising approach to promote bioengineering competitiveness and advantages over chemical engineering. Conclusion: SOS technology was demonstrated as an economic and universally applicable approach to bio-based fuels and chemicals production by whole-cell catalysis. The novel technology greatly promotes the competitiveness of bioengineering for chemical engineering, and provides a promising platform for the green and environmental use of biofuels.

We designed a technology to combined biotechnology, chemical and electrochemical techniques to achieve furoic acid bio-production from bio-toxic furfural.

A basic scheme of using 2,4-dinitrophenol (2,4-DNP) as an uncoupler between electron transport chain and oxidative phosphorylation for the biochemical regulation of Gluconobacter oxydans (G. oxydans) is raised. Under the weakly acidic environment, the lipophilic 2,4-DNP as an uncoupling agent destroys the electrochemical proton (H+) gradient in mitochondria, which leads to a loss of the driving force for adenosine triphosphate (ATP) synthesis. Based on the main enzyme system of G. oxydans, four typical substrates were studied for exploring the biochemical effects of uncoupling on the cells. As a result, it was found that under uncoupling conditions, cells receive a feedback signal of ATP deficiency, which promotes the utilization of catabolized substrates such as sorbitol and glucose through the substrate level phosphorylation pathway in order to make up for the deficiency of ATP. The proposal of strategy has a further understanding of the basic biochemical knowledge of G. oxydans and lays a theoretical foundation for the directional regulation of G. oxydans.