At Cu2+ increases PhaR expression and consequently changes the carbon flow. > 자유게시판

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At Cu2+ increases PhaR expression and consequently changes the carbon flow. More carbon sources was used to produce intracellular poly--hydroxybutyrate (PHB). Increases in PHB as a storage material bring about increases of ICP production. Conclusions: Bacillus thuringiensis X022 mainly expresses Cry1Ca, Cry1Ac, and Cry1Da. Cu2+ increases the expression of Cry1Da, Cry1Ca, and also enhances the toxicity of fermentation broth to S. exigua and H. armigera. Keywords: Bacillus thuringiensis, Cu2+, Insecticidal crystal proteins, Proteome, PhaR Background The toxicity of insecticidal crystal proteins (ICP) produced by Bacillus thuringiensis to agricultural pests and disease vectors is well known. The species has been successfully used as a microbial insecticide and provides large sources of genes for recombinant bacteria and insect-resistant transgenic plants [1?]. Because of the development of insect resistance to B. thuringiensis [4, 5], however, screening for new serotypes that bear novel crystal genes is an important endeavor. ICP are secondary metabolites, and certain conditions are necessary for their efficient synthesis. Optimization*Correspondence: syj6253@hotmail.com; dingxuezhi@hunnu.edu.cn Xuemei Liu and Mingxing Zuo contribute equally to this work College of Life Science, Hunan Provincial Key Laboratory of Microbial Molecular Biology-State Key Laboratory Breeding Base of Microbial Molecular Biology, Hunan Normal University, Changsha 410081, Chinaof fermentation conditions can lead to high production of ICP. Some metal ions act as cofactors in holoenzymes and influence the activity of enzyme proteins, ultimately changing the metabolic processes of organisms. Reports showed that some metal ions at trace amounts can significantly stimulate or suppress ICP synthesis. I en et al. [6] studied the effects of mineral elements, including MgSO4?H2O, CaCl2?H2O, MnSO4 2O, CuSO4?H2O, FeCl3, and ZnSO4?H2O, on the biosynthesis of crystal proteins in B. thuringiensis 81. Results showed that Mg and Cu are the most important metals for the biosynthesis of 135 and 65 kDa toxin components, in that the former was essential and the latter was greatly stimulatory at 10-7?0-6 mol/L concentration. Mn favors toxin production at concentrations ranging from 10-5 to 3 ? 10-4 mol/L, whereas Zn and Ca have no effect on toxin formation. kan et al.?2015 Liu et al. This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http:// creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give PubMed ID:https://www.ncbi.nlm.nih.gov/pubmed/16989806 appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/ zero/1.0/) applies to the data made available in this article, unless otherwise stated.Liu et al. Microb Cell Fact (2015) 14:Page 2 of[7] investigated the factors influencing Cry11Aa and Cry4Ba synthesis in B. thuringiensis subsp. israelensis HD500. Results showed that Mn is the most critical element for the biosynthesis of both toxins at 10-6 Capecitabine mol/L concentration. Mg and Ca favor toxin production at concentrations of 8 ? 10-3 and 5.5 ? 10-4 mol/L, respectively, whereas Fe, Zn, and Cu do not favor biosynthesis. Kurt et al. [8] found that omission of FeSO4 from the medium results in reductions in Cry3Aa yield in B.