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1.
Bacillus thuringiensis is a well-known species of entomopathogenic bacteria that is widely used as a biopesticide against many insect pests. Insecticidal proteins, coded for by genes located in plasmids, form typical parasporal, crystalline inclusions during sporulation. In this report, an unusual strain of B. thuringiensis subserovar oyamensis (LBIT-113), isolated from living larvae of Anopheles pseudopunctipennis in Mexico, was characterized by its ultrastructure, the protein composition of its parasporal crystal, plasmid pattern, and toxicological properties against several insect and noninsect targets. The parasporal crystal is enclosed within the spore's outermost envelope (exosporium), as determined by transmission electron microscopy, and exhibits a square, flat shape. Its main components are two proteins with sizes of 88 and 54 kDa. Despite some crystal morphology resemblance, both proteins are immunologically unrelated to the Cry IIIA protein, as shown by immunoblot analysis, when probed with antisera raised against the 88-kDa protein and the Cry IIIA protein. Partial N-terminal sequence of the 88-kDa protein revealed a unique amino acid arrangement among the Cry proteins. Solubilization of the crystal proteins was achieved at 3.3 M NaBr, and its digestion with trypsin showed only one ca. 60-kDa peptide, as observed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The patterns of three plasmids of strain LBIT-113 were considerably different from those of B. thuringiensis subspp. kurstaki, tenebrionis, and israelensis. Parasporal crystals showed no toxicity to larvae of four species of caterpillar, three species of mosquito, two species of beetle, one species of cricket, one species of ant, one species of aphid, one species of nematode, one species of ostracod, one species of ameba, and one species of rotifer. 相似文献
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一株抗G- 菌和酵母菌的乳酸乳球菌的分离鉴定与抗菌活性 总被引:1,自引:0,他引:1
以G+ 菌金黄色葡萄球菌(Staphylococcus aureus)作为指示菌, 通过抑菌筛选法从生牛奶中初筛得到具有抑菌活性的14株细菌菌株, 然后通过个体形态与培养特征观测、部分生理生化反应、G + C mol%测定、16S rDNA序列比对分析、PCR扩增特异性N-乙酰胞壁酸水解酶基因和序列对比分析等鉴定, 确定其中的一株具有较高抑菌活性的分离株为乳酸乳球菌乳酸亚种(Lactococcus lactis subsp. lactis)菌株, 命名为MB191。对多种G+ 细菌、G- 细菌、酵母菌和丝状真菌的对峙培养抗性测定结果表明, MB191除对供试G+ 细菌具有较高的抑菌活性以外, 还对丁香假单胞菌(Pseudomonas syringae)、荧光假单胞菌(P. fluorescens)等G- 细菌和汉逊德巴利酵母(Debaryomyces hansenii)等具有明显的抑菌活性。乳酸乳球菌的这一特性目前尚未见文献报道。 相似文献
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Characterization of a Novel Yeast SNARE Protein Implicated in
Golgi Retrograde Traffic 总被引:13,自引:10,他引:3 下载免费PDF全文
Vladimir V. Lupashin Irina D. Pokrovskaya James
A. McNew M. Gerard Waters 《Molecular biology of the cell》1997,8(12):2659-2676
The protein trafficking machinery of eukaryotic cells is employed for protein secretion and for the localization of resident proteins of the exocytic and endocytic pathways. Protein transit between organelles is mediated by transport vesicles that bear integral membrane proteins (v-SNAREs) which selectively interact with similar proteins on the target membrane (t-SNAREs), resulting in a docked vesicle. A novel Saccharomyces cerevisiae SNARE protein, which has been termed Vti1p, was identified by its sequence similarity to known SNAREs. Vti1p is a predominantly Golgi-localized 25-kDa type II integral membrane protein that is essential for yeast viability. Vti1p can bind Sec17p (yeast SNAP) and enter into a Sec18p (NSF)-sensitive complex with the cis-Golgi t-SNARE Sed5p. This Sed5p/Vti1p complex is distinct from the previously described Sed5p/Sec22p anterograde vesicle docking complex. Depletion of Vti1p in vivo causes a defect in the transport of the vacuolar protein carboxypeptidase Y through the Golgi. Temperature-sensitive mutants of Vti1p show a similar carboxypeptidase Y trafficking defect, but the secretion of invertase and gp400/hsp150 is not significantly affected. The temperature-sensitive vti1 growth defect can be rescued by the overexpression of the v-SNARE, Ykt6p, which physically interacts with Vti1p. We propose that Vti1p, along with Ykt6p and perhaps Sft1p, acts as a retrograde v-SNARE capable of interacting with the cis-Golgi t-SNARE Sed5p. 相似文献
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Characterization of a Photosynthetic Mutant Strain of Chlamydomonas reinhardi Deficient in Phosphoribulokinase Activity 总被引:3,自引:8,他引:3 下载免费PDF全文
A mutant strain of the unicellular green alga, Chlamydomonas reinhardi, is unable to fix carbon dioxide by photosynthesis because it is deficient in phosphoribulokinase activity. The absence of light-dependent carbon dioxide fixation in cells of the mutant strain supports the operation of the Calvin-Benson scheme of photosynthetic carbon dioxide fixation in this organism. No deficiency other than low phosphoribulokinase activity was found which would account for the inability of cells of the mutant strain to fix carbon dioxide by photosynthesis. Activities comparable to those in the wild-type strain were found for eight other enzymes of the Calvin cycle and two enzymes associated with the C4 dicarboxylic acid pathway. The normal rates of nicotinamide adenine dinucleotide phosphate photoreduction and of photosynthetic phosphorylation observed in chloroplast fragments prepared from cells of the mutant strain indicated that the photosynthetic electron transport chain in the mutant is intact. 相似文献
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扣囊复膜酵母(Saccharomycopsis fibuligera)因具有较强的a-淀粉酶以及葡聚糖酶活性, 使其在以淀粉为唯一碳源的培养基上能够良好的生长。从其基因组中克隆了a-淀粉酶的编码区, 构建了由酵母磷酸甘油酸激酶基因(PGK1)启动子、酿酒酵母a-因子信号序列以及扣囊复膜酵母a-淀粉酶基因编码序列组成的基因表达盒。将该表达盒插入到质粒pPLZ-2的ILV2基因序列内部, 使其两翼具有ILV2基因的同源区。将该表达盒通过同源重组的方式整合到啤酒酵母工业菌株YSF-5的a-乙酰乳酸合成酶(AHAS)基因ILV2内部。在以淀粉为唯一碳源的培养基上进行转化子的筛选。通过多对引物PCR、a-淀粉酶活性以及AHAS活性分析对转化子进行鉴定, 得到一株具有a-淀粉酶分泌表达活性、较低AHAS活性, 并且发酵液中双乙酰产量也相对较低的啤酒酵母工程菌。该菌株在非选择压力条件下连续培养50代后仍然保持其遗传稳定性。还对pH、温度以及金属离子对该转化菌株的a-淀粉酶活性的影响进行了研究。由于所构建的菌株不含有非酵母来源的DNA, 所以生物安全性相对较高, 对酵母育种以及啤酒生产工业都具有较为重要的意义。 相似文献
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Philip R. Bennallack Scott R. Burt Michael J. Heder Richard A. Robison Joel S. Griffitts 《Journal of bacteriology》2014,196(24):4344-4350
Thiopeptides are small (12- to 17-amino-acid), heavily modified peptides of bacterial origin. This antibiotic family, with more than 100 known members, is characterized by the presence of sulfur-containing heterocyclic rings and dehydrated residues within a macrocyclic peptide structure. Thiopeptides, including micrococcin P1, have garnered significant attention in recent years for their potent antimicrobial activity against bacteria, fungi, and even protozoa. Micrococcin P1 is known to target the ribosome; however, like those of other thiopeptides, its biosynthesis and mechanisms of self-immunity are poorly characterized. We have discovered an isolate of Staphylococcus epidermidis harboring the genes for thiopeptide production and self-protection on a 24-kb plasmid. Here we report the characterization of this plasmid, identify the antimicrobial peptide that it encodes, and provide evidence of a target replacement-mediated mechanism of self-immunity. 相似文献
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扣囊复膜酵母(Saccharomycopsis fibuligera)因具有较强的a-淀粉酶以及葡聚糖酶活性, 使其在以淀粉为唯一碳源的培养基上能够良好的生长。从其基因组中克隆了a-淀粉酶的编码区, 构建了由酵母磷酸甘油酸激酶基因(PGK1)启动子、酿酒酵母a-因子信号序列以及扣囊复膜酵母a-淀粉酶基因编码序列组成的基因表达盒。将该表达盒插入到质粒pPLZ-2的ILV2基因序列内部, 使其两翼具有ILV2基因的同源区。将该表达盒通过同源重组的方式整合到啤酒酵母工业菌株YSF-5的a-乙酰乳酸合成酶(AHAS)基因ILV2内部。在以淀粉为唯一碳源的培养基上进行转化子的筛选。通过多对引物PCR、a-淀粉酶活性以及AHAS活性分析对转化子进行鉴定, 得到一株具有a-淀粉酶分泌表达活性、较低AHAS活性, 并且发酵液中双乙酰产量也相对较低的啤酒酵母工程菌。该菌株在非选择压力条件下连续培养50代后仍然保持其遗传稳定性。还对pH、温度以及金属离子对该转化菌株的a-淀粉酶活性的影响进行了研究。由于所构建的菌株不含有非酵母来源的DNA, 所以生物安全性相对较高, 对酵母育种以及啤酒生产工业都具有较为重要的意义。 相似文献
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Identification and Characteristics of a Novel Burkholderia Strain with Broad-Spectrum Antimicrobial Activity 下载免费PDF全文
Cody C. Cain Alexis T. Henry Robert H. Waldo III Lester J. Casida Jr. Joseph O. Falkinham III 《Applied microbiology》2000,66(9):4139-4141
A Burkholderia strain isolated from soil is capable of inhibiting the growth of bacteria, plant-pathogenic fungi, pathogenic yeasts, and protozoa. Inhibition does not involve cell contact or the presence of living cells, suggesting that at least a substantial portion of the antimicrobial activity is due to the excretion of extracellular compounds. 相似文献
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Localization of the Enzyme System Involved in Anaerobic Reduction of Azo Dyes by Sphingomonas sp. Strain BN6 and Effect of Artificial Redox Mediators on the Rate of Azo Dye Reduction 总被引:4,自引:1,他引:4 下载免费PDF全文
The effect of different artificial redox mediators on the anaerobic reduction of azo dyes by Sphingomonas sp. strain BN6 or activated sludge was investigated. Reduction rates were greatly enhanced in the presence of sulfonated anthraquinones. For strain BN6, the presence of both cytoplasmic and membrane-bound azo reductase activities was shown. 相似文献
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Characterization of the Porphyromonas gingivalis FtsZ Containing a Novel GTPase Activity 总被引:5,自引:0,他引:5
The FtsZ protein is a GTPase that is essential for cell division. We have cloned, sequenced, and expressed the FtsZ (PgFtsZ)
gene from the Porphyromonas gingivalis, an oral, anaerobic, rod-shaped bacterium implicated in progressive periodontal disease. The PgFtsZ gene consisted of 1374
bp and coded for an acidic protein with a calculated molecular mass of 50,253 Da. The deduced amino acid sequence exhibited
a significant homology with E. coli FtsZ (54% identical residues). Like other prokaryotic FtsZs, PgFtsZ possessed the clear motifs for GTP binding (GGGTGTG)
and hydrolysis (NLDFADV). When PgFtsZ was overexpressed in E. coli, cell division was inhibited. Recombinant PgFtsZ was purified to homogeneity and characterized. The purified PgFtsZ exhibited
GTPase activity even in the absence of Mg2+, and completely retained its activity with EDTA. Furthermore, Na+ and K+ ions inhibited its GTPase activity in a dose-dependent manner. These results suggest that PgFtsZ contains an atypical GTPase
activity that has not been previously described.
Received: 25 May 2001 / Accepted: 8 August 2001 相似文献
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《Bioscience, biotechnology, and biochemistry》2013,77(1):296-299
A deep-sea yeast, Cryptococcus liquefaciens strain N6, produces two polygalacturonases, p36 and p40 (N6-PGases). These N6-PGases were highly active at 0–10 °C in comparison to a PGase from Aspergillus japonicus. The hydrolytic activity of these N6-PGases remained almost unchanged up to a hydrostatic pressure of 100 MPa at 24 °C with a very small activation volume of ?1.1 ml/mol. At 10 °C, however, the activation volume increased to 3.3 or 5.4 ml/mol (p36 and p40, respectively), suggesting that the enzyme–substrate complexes can expand at their transition states. We speculate that such a volume expansion upon forming the enzyme–substrate complexes contributes to decreasing the activation energy for hydrolysis. This can account for the high activity of N6-PGases at low-temperature. 相似文献
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Liljeström-Suominen PL Joutsjoki V Korhola M 《Applied and environmental microbiology》1988,54(1):245-249
Molasses is widely used as a substrate for commercial yeast production. The complete hydrolysis of raffinose, which is present in beet molasses, by Saccharomyces strains requires the secretion of alpha-galactosidase, in addition to the secretion of invertase. Raffinose is not completely utilized by commercially available yeast strains used for baking, which are Mel. In this study we integrated the yeast MEL1 gene, which codes for alpha-galactosidase, into a commercial mel baker's yeast strain. The Mel phenotype of the new strain was stable. The MEL1 gene was expressed when the new Mel baker's yeast was grown in molasses medium under conditions similar to those used for baker's yeast production at commercial factories. The alpha-galactosidase produced by this novel baker's yeast strain hydrolyzed all the melibiose that normally accumulates in the growth medium. As a consequence, additional carbohydrate was available to the yeasts for growth. The new strain also produced considerably more alpha-galactosidase than did a wild-type Mel strain and may prove useful for commercial production of alpha-galactosidase. 相似文献
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Chen Li Yin Lijuan Peng Peng Zhou Qingfeng Du Yunping Zhang Yun Xue Chunyi Cao Yongchang 《中国病毒学》2020,35(5):517-527
Virologica Sinica - Since 2012, the clinical cases of inclusion body hepatitis showed an increasing trend in China, causing considerable economic losses to the poultry industry. In this study, a... 相似文献
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Background
Indigoids, as popular dyes, can be produced by microbial strains or enzymes catalysis. However, the new valuable products with their transformation mechanisms, especially inter-conversion among the intermediates and products have not been clearly identified yet. Therefore, it is necessary to investigate novel microbial catalytic processes for indigoids production systematically.Findings
A phenol hydroxylase gene cluster (4,606 bp) from Arthrobacter sp. W1 (PHw1) was obtained. This cluster contains six components in the order of KLMNOP, which exhibit relatively low sequence identities (37–72%) with known genes. It was suggested that indole and all the tested indole derivatives except for 3-methylindole were transformed to various substituted indigoid pigments, and the predominant color products derived from indoles were identified by spectrum analysis. One new purple product from indole, 2-(7-oxo-1H-indol-6(7H)-ylidene) indolin-3-one, should be proposed as the dimerization of isatin and 7-hydroxylindole at the C-2 and C-6 positions. Tunnel entrance and docking studies were used to predict the important amino acids for indoles biotransformation, which were further proved by site-directed mutagenesis.Conclusions/Significance
We showed that the phenol hydroxylase from genus Arthrobacter could transform indoles to indigoids with new chemical compounds being produced. Our work should show high insights into understanding the mechanism of indigoids bio-production. 相似文献19.
Characterization of a Novel Angular Dioxygenase from Fluorene-Degrading Sphingomonas sp. Strain LB126 下载免费PDF全文
Luc Schuler Sinad M. Ní Chadhain Yves Jouanneau Christine Meyer Gerben J. Zylstra Pascal Hols Spiros N. Agathos 《Applied microbiology》2008,74(4):1050-1057
In this study, the genes involved in the initial attack on fluorene by Sphingomonas sp. strain LB126 were investigated. The α and β subunits of a dioxygenase complex (FlnA1-FlnA2), showing 63 and 51% sequence identity, respectively, to the subunits of an angular dioxygenase from the gram-positive dibenzofuran degrader Terrabacter sp. strain DBF63, were identified. When overexpressed in Escherichia coli, FlnA1-FlnA2 was responsible for the angular oxidation of fluorene, 9-hydroxyfluorene, 9-fluorenone, dibenzofuran, and dibenzo-p-dioxin. Moreover, FlnA1-FlnA2 was able to oxidize polycyclic aromatic hydrocarbons and heteroaromatics, some of which were not oxidized by the dioxygenase from Terrabacter sp. strain DBF63. The quantification of resulting oxidation products showed that fluorene and phenanthrene were the preferred substrates of FlnA1-FlnA2. 相似文献
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Purification and Characterization of a Novel Bacteriocin Produced by Enterococcus faecalis Strain RJ-11 下载免费PDF全文
Yukio Yamamoto Yoshikazu Togawa Makoto Shimosaka Mitsuo Okazaki 《Applied microbiology》2003,69(10):5746-5753
Lactic acid bacteria exhibiting activity against the gram-positive bacterium Bacillus subtilis were isolated from rice bran. One of the isolates, identified as Enterococcus faecalis RJ-11, exhibited a wide spectrum of growth inhibition with various gram-positive bacteria. A bacteriocin purified from culture fluid, designated enterocin RJ-11, was heat stable and was not sensitive to acid and alkaline conditions, but it was sensitive to several proteolytic enzymes. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis revealed that enterocin RJ-11 had a molecular weight of 5,000 in its monomeric form. The amino acid sequence determined for purified enterocin RJ-11 exhibited high levels of similarity to the sequences of enterocins produced by Enterococcus faecium. 相似文献