双组分系统和鞭毛相关蛋白的研究进展

Flagella is the motile organ of bacteria, and bacteria are driven by the flagella to move toward the best niche that is beneficial to their survival. The rotary direction of flagella is controlled by the flagellar motor. Chemotactic two-component system is an important link between the external signal stimulation and bacterial flagellar movement. The rotor of the flagellar motor is at the output of the bacterial chemotaxis pathway. Both of them contribute to the formation of biofilm, quorum sensing, stress response, and bacterial virulence. Based on their close relationship and important physiological roles and, the advances of the effect of chemotactic two-compo nent system and flagella-related proteins were reviewed in this paper</p

Function analysis of flagellar genes fliN and fliM in Azorhizobium caulinodans ORS571

[Objective] To investigate the phenotypes of Azorhizobium caulinodans ORS57 mutant strains that lacked the flagellar motor proteins FliN and FliM respectively, and the functional mechanism of these proteins. [Methods] The gene knock-out mutant strains (DeltafliN, DeltafliM) were constructed by homologous recombination and triparental conjugation. The phenotypes including cell growth, chemotaxis, exopolysaccharide production, biofilm formation and cell flocculation were investigated. [Results] Mutants DeltafliN and DeltafliM did not shown any difference in cell growth compared with the wild-type strain. However, both mutants lost their flagella when observed under electron microscope. In addition, DeltafliN and DeltafliM were impaired in chemotaxis, exopolysaccharide production, and biofilm formation. To the contrary, the flocculation ratio of both mutants was higher than that of the wild-type strain within the same amount of time. [Conclusion] The flagellar genes fliN and fliM could regulate the flagellum formation, cell motility, exopolysaccharide production, biofilm formation and cell flocculation of Azorhizobium caulinodans ORS571.</p

Characterization of diguanylate cyclase metabolism-related gene in Azorhizobium caulinodans ORS571

[Objective] To study the phenotypes of Azorhizobium caulinodansORS571 mutant strain lacking the diguanylate cyclase AZC-2412, and to explore its functional mechanism. [Methods] We constructed the gene knockout system of rhizobia based on the homologous recombination of cre-loxp, and the mutant strain was constructed by the triparental conjugation. Growth rate, chemotactic ability, exopolysaccharide production, biofilm formation and other phenotypes of the wild type and mutant strains were studied. [Results] The mutant strain had almost the same growth rate as the wild type. Compared with the wild type, the mutant strain impaired in exopolysaccharide production, chemotaxis behavior and biofilm formation due to lower levels of c-di-GMP in cells. [Conclusion] The deletion of the diguanylate cyclase AZC-2412 reduces level of c-di-GMP levels. It had a regulatory effect on the exopolysaccharide production, bacterial motility, biofilm formation, cell flocculation of Azorhizobium caulinodans ORS571 and its interaction with host plant.</p

Stem nodule rhizobium for promoting growth of wheat as well as construction and application thereof

本发明涉及农业微生物领域，具体地说是一种小麦促生茎瘤固氮根瘤菌及其构建和应用。本发明菌株具有良好的固氮、定植与促生特性，可以增加土壤养分，提高肥料有效性，促进植物对土壤养分吸收，具有开发成促进农作物生长的微生物接种剂或微生物菌肥的良好前景。本发明针对小麦具有显著的促生效果，菌株良好地促生特性促进了小麦生长

页岩气开采中的若干力学前沿问题

页岩气的开采涉及破裂和收集输运两个关键过程.如何实现2000 m以下、复杂地应力作用下、多相复杂介质组分的页岩层内网状裂纹的形成,同时将孔洞、缝隙中的游离、吸附气体进行高效收集,涉及到诸多的核心力学问题.这一工程过程涵盖了力学前沿研究的诸多领域:介质和裂纹从纳米尺度到千米尺度的空间跨越,游离、吸附气体输运过程中微秒以下的时间尺度事件到历经数年开采的时间尺度跨越,不同尺度上流体固体的相互作用,以及压裂过程中通过监测信息反演内部破坏状态等.针对近年来我们国家页岩气勘探开发工作所取得的成就及后续发展中面临的前沿力学问题,在综合介绍页岩气藏的基本特征和开发技术的基础上,以页岩气开采中的若干力学前沿问题为主线,从页岩力学性质及其表征方法、页岩气藏实验模拟技术、页岩气微观流动机制及流固耦合特征、水力压裂过程数值模拟方法、水力压裂过程微地震监测技术、高效环保的无水压裂技术等6个方面的最新研究进展进行了总结和展望,结合页岩气藏开发的工程实践,深入探究了其中力学关键问题,以期对从事页岩气领域的开发和研究的从业人员提供理论基础,同时,该方面的内容对力学学科、尤其是岩土力学领域的科研工作也具有重要指导价值