BackgroundD-2,3-butanediol has many industrial applications such as chiral reagents, solvents, anti-freeze agents, and low freezing point fuels. Traditional D-2,3-butanediol producing microorganisms, such as Klebsiella pneumonia and K. xoytoca, are pathogenic and not capable of producing D-2,3-butanediol at high optical purity. Bacillus licheniformis is a potential 2,3-butanediol producer but the wild type strain (WX-02) produces a mix of D- and meso-type isomers. BudC in B. licheniformis is annotated as 2,3-butanediol dehydrogenase or acetoin reductase, but no pervious experiment was performed to verify this hypothesis.ResultsWe developed a genetically modified strain of B. licheniformis (WX-02 ΔbudC) as a D-2,3-butanediol producer with high optimal purity. A marker-less gene deletion protocol based on a temperature sensitive knock-out plasmid T2-Ori was used to knock out the budC gene in B. licheniformis WX-02. The budC knock-out strain successfully abolished meso-2,3-butanediol production with enhanced D-2,3-butanediol production. No meso-BDH activity was detectable in cells of this strain. On the other hand, the complementary strain restored the characteristics of wild strain, and produced meso-2,3-butanediol and possessed meso-BDH activity. All of these data suggested that budC encoded the major meso-BDH catalyzing the reversible reaction from acetoin to meso-2,3-butanediol in B. licheniformis. The budC knock-out strain produced D-2,3-butanediol isomer only with a high yield of 30.76 g/L and a productivity of 1.28 g/L-h.ConclusionsWe confirmed the hypothesis that budC gene is responsible to reversibly transfer acetoin to meso-2,3-butanediol in B. licheniformis. A mutant strain of B. licheniformis with depleted budC gene was successfully developed and produced high level of the D-2,3-butanediol with high optimal purity.

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The energy Internet is a complex multi-grid flow system, which is based on the power system, the Internet and other cutting-edge information technologies, with distributed renewable energy as the main primary energy and closely coupled with natural gas network, transportation network and other systems. The power grid technology has to develop to support the energy Internet construction. This paper discusses the changes and challenges in the asset environment, asset types, asset scope and asset risk under the energy Internet. Then the corresponding implementation methods of power grid technology to supporting energy Internet construction are put forward. The research results can provide reference for power grid companies to implement power technical innovation.

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In recent years, the changing trend and causes of power grid engineering are diversified and complicated. In view of this problem, it is impossible to determine the influencing factors by quantitative analysis. Selection in order to solve this problem, we collect relevant power transmission project data, since 2015. First, we determine the control index system, 20 factors affected substation project, 19 influence factors affected route project, and then use AHP method to establish the new situation under the background of grid engineering control model. Through the MATLAB software, we determine the weight of each influence factor. Finally, the factors that have great influence on power grid engineering control are obtained according to the order of weight. Thus, it lays the foundation for the orderly development of better control grid engineering in the future.