941 resultados para Bacillus pumilus


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Electrospray ionization (ESI) combined with multiple-stage tandem mass spectrometry (MSn) was used to directly analyze the glycolipid mixture from bacteria Bacillus pumilus without preliminary separation. Full scan ESI-MS revealed the composition of picomole quantities of glycerolglycolipid species containing C-14-C-19 fatty acids, some of which were monounsaturated, Two main components were identified from their molecular masses and fragmentation pathways. The fragmentation pathway of the known compound compared with the investigated compound verified the proposed structure as 1(3)-acyl-2-pentadecanoyl-3(1)-O-[beta-D-glucopyranosyl-(1-->6)-O-beta-D-glucopyranosyl]-sn-glycerols. A comparison of the multiple tandem mass spectra of the different alkali-metal cation adducts indicates that the intensity of fragments and the dissociation pathways are dependent on the alkali-metal type, The basic structures of glycerolglycolipids were reflected clearly from the fragmentation patterns of the sodium cations, The intense fragments of the sugar residue from the precursor ions were obtained from the lithiated adduct ions. ESI-MSn spectra of [M + K](+) ions did not provide as much fragmentation as [M + Na](+) and [M + Li](+) adducts, but their spectra allow the position of glycerol acylation to be determined. On the basis of MS2 spectra of[M + K](+) ions, it was established that all components have a C-15:0 fatty acid at the sn-2 position of the glycerol backbone and C-14-C-19 acids at the sn-1 position of the glycerol backbone. Copyright (C) 1999 John Wiley & Sons, Ltd.

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In the present studies it is clear that Bacillus pumilus xylanase is having the characteristic suited for an industrial enzyme (xylanases that are active and stable at elevated temperatures and alkaline pH are needed). SSF production of xylanases and its application appears to be an innovative technology where the fermented substrate is the enzyme source that is used directly in the bleaching process without a prior downstream processing. The direct use of SSF enzymes in bleaching is a relatively new biobleaching approach. This can certainly benefit the bleaching process to lower the xylanase production costs and improve the economics and viability of the biobleaching technology. The application of enzymes to the bleaching process has been considered as an environmentally friendly approach that can reduce the negative impact on the environment exerted by the use of chlorine-based bleaching agents. It has been demonstrated that pretreatment of kraft pulp with xylanase prior to bleaching (biobleaching) can facilitate subsequent removal of lignin by bleaching chemicals, thereby, reducing the demand for elemental chlorine or improving final paper brightness. Using this xylanase pre-treatment, has resulted in an increased of brightness (8.5 Unit) when compared to non-enzymatic treated bleached pulp prepared using identical conditions. Reduction of the consumption of active chlorine can be achieved which results in a decrease in the toxicity, colour, chloride and absorbable organic halogen (AOX) levels of bleaching effluents. The xylanase treatment improves drainage, strength properties and the fragility of pulps, and also increases the brightness of pulps. This positive result shows that enzyme pre-treatment facilitates the removal of chromophore fragments of pulp there by making the process more environment friendly

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Among extremophiles, microorganisms resistant to ultraviolet radiation (UVR) have been known to produce a variety of metabolites (i.e., extremolytes). We hypothesized that natural microbial flora on elevated land (hills) would reveal a variety of UVR-resistant extremophiles and polyextremophiles with modulated proteins and enzymes that had biotechnological implications. Microorganisms Cellulosimicrobium cellulans UVP1 and Bacillus pumilus UVP4 were isolated and identified using 16S rRNA sequencing, and showed extreme UV resistance (1.03 x 106 and 1.71 x 105 similar to J/m2, respectively) from elevated land soil samples along with unique patterns of protein expression under UVR and non-UVR. A broad range of cellulolytic activity on carboxymethyl cellulose agar plates in C. cellulans UVP1 and B. pumilus UVP4 was revealed at varying pH, temperature, and inorganic salt concentration. Further, the microbial strain B. pumilus UVP4 showed the basic characteristics of a novel group: polyextremophiles with significance in bioenergy.

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O aumento da concentração de dióxido de carbono (CO2) atmosférico previsto para as próximas décadas poderá provocar alterações no manejo de doenças, devido a alteração na microbiota que atua no controle biológico. O agente causal da ferrugem do cafeeiro (Hemileia vastatrix) foi testado com seu antagonista Bacillus pumilus em discos foliares (1,5 cm) em bandejas com, aproximadamente, 380, 430, 700 e 1300 ppm de CO2. O antagonista foi inoculado 24 horas antes e depois da inoculação do patógeno e simultaneamente. As bandejas foram vedadas e incubadas no escuro por 24 horas e, a seguir, mantidas em fotoperíodo de 12 horas, a 22 °C e 100% de umidade relativa, com injeção freqüente de CO2. Após 32 dias, foram iniciadas as avaliações de esporulação nas lesões dos discos foliares. Houve diferença quanto à severidade da doença entre os tratamentos com injeção de CO2, sendo maior na concentração de 700 ppm. Não se obteve diferença entre os períodos de inoculação do antagonista. Nessas condições, o efeito do aumento da concentração de CO2 não interfere na ação do antagonista no controle biológico da ferrugem do cafeeiro.

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Pós-graduação em Agronomia (Proteção de Plantas) - FCA

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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While conducting experiments to investigate antimicrobial peptides of amphibians living in the Yunnan-Sichuan region of southwest China, a new family of antimicrobial peptides was identified from skin secretions of the rufous-spotted torrent frog, Amolops loloensis. Members of the new peptide family named amolopins are composed of 18 amino acids with a unique sequence, for example, NILSSIVNGINRALSFFG. By BLAST search, amolopins did no show similarity to any known peptides. Among the tested microorganisms, native and synthetic peptides only showed antimicrobial activities against Staphylococcus aureus ATCC2592 and Bacillus pumilus, no effects on other microorganisms. The CD spectroscopy showed that it adopted a structure of random combined with beta-sheet in water, Tris-HCl or Tris-HCl-SDS. Several cDNAs encoding amolopins were cloned from the skin cDNA library of A. loloensis. The precursors of amolopin are composed of 62 amino acid residues including predicted signal peptides, acidic propieces, and mature antimicrobial peptides. The preproregion of amolopin precursor comprises a hydrophobic signal peptide of 22 residues followed by an 18 residue acidic propiece which terminates by a typical prohormone processing signal Lys-Arg. The preproregions of precursors are very similar to other amphibian antimicrobial peptide precursors but the mature amolopins are different from other antimicrobial peptide families. The remarkable similarity of preproregions of precursors that give rise to very different antimicrobial peptides in distantly related frog species suggests that the corresponding genes form a multigene family originating from a common ancestor. (C) 2008 Elsevier Masson SAS. All rights reserved.

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天然产物和生物样品由于可获得的样品量少,并且它们常常是以多种结构相近的组份混合存在,因此对其结构的分析一直是具有挑战性的。先进质谱技术的不断问世,极大地促进了对天然产物和生物样品的直接分析。本论文采用气相色谱/质谱联用技术对天然麝香和麝鼠香的苯提取物进行了定性和定量分析。同时,利用基质辅助激光解吸飞行时间质谱和电喷雾多级串联质谱对从菌种中分离得到的糖脂混合物进行了结构鉴定和质谱研究。实验结果表明,质谱作为一种快速而有效的分析方法,是分析天然产物和生物样品的不可缺少的手段之一。1. 天然麝香和麝鼠香苯提取物的气相色谱/质谱分析 根据保留时间和电子轰击质谱图,鉴定了麝鼠香苯提取物中的33个组份,其中多数组分属于新发现的成分。在麝鼠香苯提取物中,大环酮/醇为主要组成,并且它们都以奇数环酮/醇的形式存在。通过与天然麝香的麝香酮比较可知,麝鼠香中不含有麝香酮。麝鼠香中与麝香酮具有相同分子量的化合物是其同分异构体,环十六烷酮,并不是多数文献所报道的麝香酮。由此可知,麝鼠香中的香气成分不是麝香酮,而是含量较高的环十五酮和环十七酮。利用单离子监控技术并结合标准麝香酮外标的方法对麝鼠香中的主要环酮化合物进行了定量分析。结果表明,各组份的含量相对稳定,不随泌香期香量的改变而变化。其中麝鼠香中的两个主香气成分环十五烷酮和环十七烯酮的含量为0.4%。2. 微生物体中糖脂混合物的生物质谱研究 利用激光解吸飞行时间质谱和电喷雾多级串联质谱对从名为Bacillus pumilus菌种中分离得到的糖脂混合物进行了直接分析。激光解吸质谱确定了其中两个主要糖脂的分子质量。糖脂在激光质谱中加合钠和钾离子的形式存在说明糖脂与碱金属离子具有较强的亲合性。电喷雾全扫描质谱结果表明此糖脂混合物是由脂肪酸链组成不同的糖脂化合物构成。通过分析和比较未知组份和已知组份的断裂途径,证实了未知组份的推测结构。糖脂加合不同碱金属离子的多级串联结果比较显示碎片离子的强度和离子的断裂途径是与碱金属的种类紧密相关的。糖脂加合钠离子的断裂途径提供了糖脂的基本骨架信息。糖脂加合锂离子得到各种有关糖基的碎裂。尽管糖脂加合钾离子不能够如同加合钠离子和加合锂离子那样产生较多的碎片离子,但是它的二级质谱可以确定糖脂的脂化位点。利用电喷雾多级串联功能,对在电喷雾质谱过程中出现的两个特殊碎片离子的断裂机理进行了探讨,同时推测了碱金属离子与糖脂化合物的作用位置。

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本论文以牛奶为原料分离出42株球菌,经鉴定其中15株为乳链球菌(Streptococcus lactis)。对15株乳链球菌进行Nisin效价测定后,确定SN-21为诱变的出发菌株(598.1IU/ml,NO.95培养基),经过硫酸二乙酯和紫外线的多次诱变后,选育出一株Nisin高产菌株(1514IU/ml,CM培养基),命名为S. L. 21 (Streptococcus lactis 21)。通过对S. L. 21发酵条件的选优,其Nisin效价达到1862IU/ml。采用紫外吸收光谱法确定S. L. 21发酵产物中的抑菌物质为Nisin。在Nisin高产菌株选育的同时,开创了Nisin应用于蕨菜罐头的加工贮藏研究。通过在蕨菜罐头中添加0.1g/kg的Nisin,降低了蕨菜罐头的杀菌温度(100 ℃)和杀菌时间(15min),保证了蕨菜的品质,提高了蕨菜罐头的贮藏安全性,这为低酸易软烂野生蔬菜食品的加工贮藏提供了一条重要途径。100 ℃,15min杀菌条件下,在加工的蕨罐头中,未添加Nisin的处理和添加苯甲酸钾(1.0g/kg)的处理,均出现胀罐,爆罐现象。经分析确定蕨菜罐头胀罐原因是由污染的细菌产气引起的。通过分离污染菌优势类群得到8株芽孢杆菌,经系统的细菌学鉴定,4~#菌株为巨大芽孢杆菌(Bacillus megaterium),8~#菌株为短小芽孢杆菌(Bacillus pumilus),其余为枯草芽孢杆菌(Bacillus subtilis)。经进一步产气试验证明5~#菌株产气快,产气量大,是引起蕨菜罐头胀罐的污染优势种,经研究发现蕨菜罐头污染菌优势种是一种枯草芽孢杆菌的新变种,命名为枯草芽孢杆菌嗜热耐盐新变种(Bacillus sutilis n. var. sp.),这株新变种具有耐热(90 ℃),耐盐(10%NaCl),产生的特点。对蕨菜罐头污染菌优势种(5~#)进行防腐剂抑菌试验发现其对Nisin敏感(MIC 500ppm),而对苯甲酸钠(MIC 1.5%)和山梨酸钾(MIC 3%)不敏感,抑菌率试验进一步证明,在允许应用范围内,只有Nisin对蕨菜罐头防腐有良好的效果,而苯甲酸钠和山梨酸钾抑菌效果均不理想。在Nisin对污染菌优势种(5~#)的溶菌作用试验中,通过电镜可以观察到,Nisin的作用首先是破坏细胞壁,细胞膜,造成细胞内物质外流,严重溶菌结果,导致污染细菌死亡。以上关于Nisin应用于蕨菜罐头防腐,蕨菜罐头污染菌优势类群的分析,污染菌优势种的研究的试验结果均为国内外首次报导。总之,通过在蕨菜罐头中添加Nisin来抑制污染菌优势种的生长敏殖,进而达到降低杀菌强度的目的,对于保证蕨菜固有的品质及今后蕨菜等野生资源的开发具有重要的意义。

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采用酪素平板、纤维蛋白平板的初筛和摇瓶复筛的方法从205株海洋微生物中筛选得到4株纤溶酶活性较强的菌株,其中菌株B5815产纤溶酶活性最高,平均达258 IU/mL。通过对菌株B5815的形态特征、生理生化特性的测定及16S rDNA序列分析,综合鉴定其为短小芽胞杆菌(Bacillus pumilus)。