Metabolic products of microorganisms. 192. The anthraquinones of the Aspergillus glaucus group. II. Biological activity

From the mycelia of Aspergillus cristatus the following anthraquionic pigments were isolated: catenarin, emodin, erythroglaucin, rubrocristin, physcion, physcion-9-anthrone, questin, viocristin, and isoviocristin. The latter two do not belong to the 9, 10-anthraquinone series but to the 1,4-anthraquinones, and so far they have not been reported among naturally occurring quinones.Emodin, catenarin, viocristin, and isoviocristin snowed antibacterial activity with minimal inhibitory concentrations ranging from 1–10 g/ml. In Bacillus brevis catenarin and emodin inhibited the incorporation of uracil and leucine preferentially. At higher concentrations the incorporation of thymidine into the trichloroacetic acid-precipitable fraction of cells was also affected. In the presence of viocristin or isoviocristin all three macromolecular syntheses came to a halt. Rubrocristin, erythroglaucin, and physcion showed no significant inhibitory effects.In Ehrlich ascites carcinoma cells catenarin, emodin, and viocristin inhibited the incorporation of uridine and thymidine. The incorporation of leucine was hardly affected.In vitro, inhibition of DNA-dependent RNA polymerase from Escherichia coli by catenarin and to a lesser extent by emodin was observed, whereas rubrocristin (catenarin-8-methyl ether), physcion, and erythroglaucin were not active.Abbreviations MIC minimal inhibitory concentration - TCA trichloroacetic acid - ECA Ehrlich ascites carcinoma Metabolic Products of Microorganisms. 191. W. Keller-Schierlein und B. Joos; Über das 4-Oxohomotyrosin, ein Abbauprodukt des Echinocandins. Helv. Chim. Acta (in press)     

Comparison of the expression of Bacillus thuringiensis full-length and N-terminally truncated vip3A gene in Escherichia coli

AIMS: Studies were performed to demonstrate the function of the putative signal peptide of Vip3A proteins in Escherichia coli. METHODS AND RESULTS: The full-length vip3A-S184 gene was isolated from a soil-isolated Bacillus thuringiensis, and the vip3AdeltaN was constructed by deleting 81 nucleotides at the 5'-terminus of vip3A-S184. Both were transformed and expressed in E. coli. About 19.2% of Vip3A-S184 proteins secreted soluble proteins and others formed inclusion bodies in the periplasmic space. In contrast, the Vip3AdeltaN was insoluble and formed inclusion bodies in the cytoplasm. Bioassay indicated that Vip3A-S184 showed different toxicity against Spodoptera exigua, Helicoverpa armigera and S. litura, but Vip3AdeltaN showed no toxicity to either of them because of the deletion of the first 27 amino acids at the N-terminus. CONCLUSIONS: The results suggest that the deleted N-terminal sequences were essential for the secretion of Vip3A-S184 protein in E. coli and might be required for toxicity. SIGNIFICANCE AND IMPACT OF THE STUDY: The function of the putative signal peptide of Vip3A protein in E. coli was investigated. These would be helpful to make clear the unknown secretion pathway of Vip3A protein in B. thuringiensis and determine the receptor-binding domain or toxic fragment of Vip3A-S184 protein.     

萎缩芽胞杆菌CKL1促盐胁迫下燕麦生长活性及其功能基因分析

【背景】青海省特殊生境孕育了特殊微生物资源。【目的】探究适合生活于高原生境的芽胞杆菌菌源。【方法】采用平板对峙法、显色法对萎缩芽胞杆菌（Bacillus atrophaeus） CKL1的拮抗、产吲哚乙酸活性进行测定,并检测耐低温、耐盐性及菌株对盐胁迫下燕麦品种（Avena sativa）“青燕1号”种子萌发、幼苗生长效应及叶绿素、脯氨酸、丙二醛的含量变化,利用二代测序技术对菌株进行基因组测序并分析相关功能基因。【结果】菌株CKL1对禾谷镰孢菌（Fusarium graminearum）、锐顶镰孢菌（Fusarium acuminatum）表现出显著的拮抗活性（抑菌圈直径>15 mm）;与Salkowski比色液反应变红,能在NaCl浓度为13%的LB培养基及4℃低温下生长,表现出一定的产吲哚乙酸、耐盐及耐低温活性;盐胁迫下,菌株CKL1对“青燕1号”种子萌发及幼苗生长具有显著促进作用,叶绿素及脯氨酸含量显著增加,丙二醛含量下降,增强了燕麦的抗盐性。菌株CKL1基因组全长为14 281 280 bp,与GO功能数据库比对注释到3 303个功能基因;基因组编码与脂肽类化合物itur...     

Water-soluble granules containing <Emphasis Type="Italic">Bacillus megaterium</Emphasis> for biological control of rice sheath blight: formulation,bacterial viability and efficacy testing

Endospores of B. megaterium were formulated in granule formulations with sodium alginate, lactose and polyvinylpyrrolidone (PVP K-30) by the wet granulation technique. The granule formulation exhibited good physical characteristics, such as high-water solubility and optimal viscosity, that would be suitable for spray application. The bacteria remained viable in the dry granule formulation at 10⁹ c.f.u./g after 24 months storage at room temperature. Under laboratory conditions, aqueous solutions of the formulation showed high activity against mycelial growth of R. solani (99.64 ± 0.14% mycelial inhibition). High viability of the bacterial antagonist on leaf sheath and leaf blade at day 7 after spraying with the formulation was observed (approximately 10⁶ c.f.u./g of plant). Application of an equivalent number of un-formulated endospores resulted in much loss of the bacterial endospores even 1 day after application. In a small pilot field study, an aqueous solution of the formulation (3%w/v) applied by spraying at days 1, 5 and 10 after pathogen inoculation of the rice plants was more effective in suppressing rice sheath blight disease than one application of a fungicide (Iprodione) at day 1. Additionally, rice plants sprayed with the aqueous solution of the granule formulation had higher panicle and whole kernel weights than those of fungicide-treated and control (untreated) plants.     

Hydroperoxide inactivation of enzymes within spores of Bacillus megaterium ATCC19213

Abstract Hydroperoxide inactivation of the protoplast enzymes enolase, aldolase and glucose-6-phosphate dehydrogenase in intact spores of Bacillus megaterium ATCC19213 was assessed by first treating the cells with lethal levels of H₂O₂, then germinating them in the presence of chloramphenicol prior to permeabilization and enzyme assays. Glucose-6-phosphate dehydrogenase proved to be more sensitive to H₂O₂than enolase or aldolase, in agreement with findings for isolated enzymes. Average D values (time for 90% inactivation) for spores treated with 0.50% H₂O₂ were 173 min for enolase, 67 min for aldolase and 32 min for glucose-6-phosphate dehydrogenase, compared with a D value of 34 min for spore killing. H₂O₂ killing of spores was found to be conditional in that recoveries of survivors were greater on complex medium than on minimal medium. Overall, it appeared that oxidative inactivation of enzymes may be important for hydroperoxide killing of spores.     

A fusion gene coding for two different δ-endotoxinsof Bacillus thuringiensis toxic to Plutella xylostella and usefulfor resistance management

Two truncated Bacillus thuringiensis -endotoxin genes, belonging to the classes cry1Ab and cry1B, and both coding for N-terminal toxic fragments of the corresponding crystal proteins, were translationally fused. Expression of the fusion gene driven by the cry1C promoter in Escherichia coli at a very high level resulted in a protein with enhanced toxicity to the diamondback moth (Plutella xylostella).     

Expression and crystallization of a Cry3Aa–Cry1Ac chimerical proteinof Bacillus thuringiensis

The insecticidal Cry1 proteins of Bacillus thuringiensis form a typical bipyramidal parasporal crystal and their protoxins contain a highly conserved C-terminal region. A chimerical gene was constructed with the coding regions of the Cry3Aa protein's toxic domain, and of the Cry1Ac protoxin's C-terminal fragment. This chimerical construction expressed a truncated (70kDa) protein in the acrystalliferous strain 4Q7 of B. thuringiensis, assembled in spherical to amorphous parasporal crystals. This protein was recognized only by antibodies raised against the Cry3Aa protein. When the protease-deficient mutant BL21 of Escherichia coli was transformed with the same chimerical construction, a complete (140kDa) chimerical protein was expressed. However, the formation of a crystalline inclusion was unclear. This protein was recognized by antibodies raised against the proteins Cry1Ac and Cry3Aa. Both chimerical proteins showed toxicity against larvae of Leptinotarsa texana, being much more active when expressed truncated in B. thuringiensis. These results suggest that the formation of bipyramidal crystals requires more than just the presence of the C-terminal region of Cryl protoxins. They also suggest that proteolysis plays an important role during the post-translational processing of Cry proteins.     

枯草芽孢杆菌壳聚糖酶水解制备低脱乙酰度壳寡糖及其组分分析

对来源于枯草芽孢杆菌菌株168(Bacillus subtilis 168)的壳聚糖酶编码基因进行了序列优化及全合成,并在毕赤酵母(Pichia pastoris)中实现了分泌表达,表达产物的蛋白质浓度达到0.30mg/ml。表达的壳聚糖酶最适p H为5.6,最适温度为55℃,比酶活达84.54U/ml。该酶在50℃及以下较稳定。利用该酶水解低脱乙酰度壳聚糖并使用超高效液相色谱-四极杆飞行时间质谱(ultra-performance liquid chromatography quadrupole time-of-flight mass spectrometry,UPLC-QTOF MS)对产物的组分进行了分离及鉴定。根据一级质谱信息,推测酶解产物中包含至少37种聚合度2~18,不同脱乙酰度的壳寡糖组分。综上,利用毕赤酵母分泌表达了来源于枯草芽孢杆菌菌株168的壳聚糖酶基因,利用表达产物水解制备了低脱乙酰度壳寡糖并对其组分进行了分析,可为后续壳寡糖结构与功能关系的研究提供参考。     

苏云金芽胞杆菌Sigma54和CcpA共同调控的基因鉴定

【目的】通过综合分析苏云金芽胞杆菌(Bacillus thuringiensis)HD73菌株Sigma54缺失突变体的转录组数据和蜡样芽胞杆菌(Bacillus cereus)ATCC 14579菌株CcpA缺失突变体的转录组数据,并进行启动子与CcpA蛋白的体外结合验证,明确Bt HD73菌株中Sigma54和CcpA共同调控的基因,丰富了对微生物的代谢调控网络的认识。【方法】以转录组测序结果为基础,通过基因同源性的比对在Bt HD73菌株中寻找受Sigma54和CcpA共同调控的基因,在这些基因中找到具有cre序列的启动子,通过凝胶阻滞验证这些启动子与CcpA蛋白的结合。【结果】Bt HD73菌株中有31个基因受Sigma54和CcpA共同调控,其中14个基因的启动子序列包含cre序列,这些启动子都可以与CcpA蛋白发生体外结合。【结论】Bt HD73菌株中有14个基因直接受CcpA的调控,同时其转录受Sigma54的控制。