芽胞杆菌模式菌株细胞脂肪酸组分的气相色谱分析

通过气相色谱对１０个芽胞杆菌模式菌株的细胞脂肪酸组分及其含量进行分析,经ＵＰＧＭＡ,ＮＴＳＹＳ－Ｐｃ系统聚类分析绘制的树状图谱可以清楚地将４个属的菌株分成４个不同的类群,而且同一类群中不同的种也表现出一定的差异。由此可见,控制芽胞杆菌的培养条件及生长状态,同样有效地使脂肪酸组分成为芽胞杆菌化学分类的重要指证。     

氮磷检测器裂解气相色谱法区分嗜热脂肪芽孢杆菌的研究

 ]用氮磷检测器和氢焰检测器分别对21株嗜热脂肪芽孢杆菌及其类属菌进行裂解气相色谱分析。借助电子计算机用聚类分析法解析细菌的裂解气相色谱图，所得树状谱中菌株间的关系与常规分类法和数值分类结果基本一致。实验结果表明，氮磷检测器在生物大分子和生物医学材料鉴别分析工作中的重要价值。     

气相色谱一四温裂解气相色谱联用仪

本文用四个并联的蒸气相裂解器在气相色谱—裂解气相色谱联用装置,四个裂解器的温度为406.554,658及768℃,解决了实用的气相色谱—裂解气相色谱联用分析要求有普遍适用的裂解温度的问题,同时得到较多较大的裂解色谱峰,使定性更加准确。     

裂解气相色谱-质谱联用法分析聚醚酰亚胺的裂解产物

应用裂解气相色谱及质谱联用法研究了3种聚醚酰亚胺(PEIM′s)的裂解行为,并根据裂解产物的结构及其相对产率推断了裂解的机理。取3种PEIM样品置于石英裂解管中,分别在550℃,650℃,750℃条件下裂解,所得产物用气相色谱-质谱联用法分析。分析中采用DB-5毛细管色谱柱,电子轰击离子源(200℃,70eV)及在m/z 29～500范围内全扫描方式,并用NIST谱库进行检索和用归一化法计算峰面积进行定量。由试验结果可知:选择在750℃进行裂解较好,在此条件下获得主要裂解产物存在的更明显的信息,有利于对产物进行详细分析和鉴定。     

显像管石墨乳的综合分离分析方法介绍

利用薄膜渗析、溶剂萃取、液固柱色谱分离、薄层色谱分离、热裂解等分离方法和红外光谱、发射谱、Ｘ射线粉末衍射、无毒分析、气相色谱、点滴试验等测试鉴定手段在对多种进口显像管石墨乳进行分离分析的基础上，建立了一套适合于各类显像管石墨乳的分离分析鉴定方法。     

裂解气相色谱-质谱联用法对香叶醇的热裂解产物分析

采用裂解气相色谱-质谱法(Py-GC-MS)研究了香叶醇热裂解性质。以氦气为载气,将香叶醇样品分别在不同温度(300,400,500,600,650,700,800℃)下进行热裂解,将热解产物直接引入气相色谱-质谱仪进行定性和半定量分析。结果表明:在700℃时香叶醇完全裂解,裂解产物可达87种。根据主要的裂解产物和其相对含量的变化对香叶醇裂解机理进行初步探讨,为香叶醇在卷烟中的作用评价提供重要的理论依据。     

裂解—毛细管气相色谱法鉴定中草药

本文尝试用裂解—毛细管气相色谱法鉴定中草药,对十四种中草药的裂解行为进行了探讨。通过比较各中草药裂解色谱图中的特征峰或八个主要峰的保留值和相对强度,借以鉴定中草药;通过比较不同产地中草药特征峰的强度,借以评价中草药的质量。文中还对用裂解色谱法鉴定中草药的条件进行了探讨。由实验结果初步看出,裂解色谱法是可以鉴定和评价中草药的。     

在线裂解-气相色谱-质谱法研究灵香草浸膏的热裂解

为了研究灵香草浸膏的热裂解行为,采用在线有氧热裂解-冷阱捕集-气相色谱-质谱联用技术,模拟卷烟燃吸状态对灵香草浸膏进行了热裂解分析,并对灵香草浸膏热裂解前后的挥发性成分进行了比较分析。从灵香草浸膏的热裂解产物中共鉴定出64种成分,占总峰面积的88.27%,主要成分为高级脂肪酸及其酯类;灵香草浸膏热裂解后的挥发性成分数量多于裂解前（45个）,说明灵香草浸膏经热裂解生成了新的化合物。热裂解前后共有的化合物有20个,主要是高级脂肪酸及其酯类、新植二烯、5-（羟甲基）-2-呋喃甲醛、3-羟基-4,5-二甲基-2（5H）-呋喃酮等化合物。在线有氧裂解模式更接近烟用添加剂样品的真实裂解状态,操作简单、快捷,结果准确。     

用裂解气相色谱法对几株霉菌的分析

本文用带有PYR-2A管式炉裂解器和C-R2AX计算机的岛津GC-9A气相色谱仪,对3株曲霉和3株青霉进行了裂解气相色谱鉴别。通过对指纹图的分析,能够较好地区分出两属之间和各菌株之间的差异,证明了裂解气相色谱分析法用于霉菌鉴别的可能性。     

废弃印刷电路板材料裂解产物的高分辨裂解气相色谱-质谱分析

采用高分辨裂解气相色谱-质谱法(PyGC-MS)分析了FR-4型印刷电路板粉末样品的裂解产物。在氦气氛围中,分别在350,450,550,650和750 ℃下对印刷电路板粉末样品进行热裂解,并通过毛细管气相色谱-质谱对裂解产物进行分析,研究了不同裂解温度下裂解产物分布以及主要裂解产物的产率与裂解温度的关系,根据热分解产物的组成,探讨了热分解反应机理。     

高效液相色谱-电喷雾质谱法分离和鉴别枯草芽孢杆菌产生的脂肽类化合物

枯草芽孢杆菌JA因产生多种脂肽类化合物而具有广阔的开发前景。JA发酵液经过离心、酸沉淀、甲醇抽提等步骤得到脂肽类化 合物的粗提物。将粗提物溶于流动相,采用反相高效液相色谱分离,对收集的洗脱峰组分进行电喷雾质谱(ESI-MS)分析。根据质荷比推 断JA菌株产生的脂肽类化合物属于3个家族,分别为surfactin, iturin和fengycin,是枯草芽孢杆菌合成的重要生物表面活性素。对一 级质谱中的主成分进行串联质谱分析,进一步确定了3种脂肽类化合物的分子结构。实验证明ESI-MS是一种鉴定脂肽类化合物及其同系 物的可靠方法。     

XPS analysis of chemical functions at the surface of Bacillus subtilis

The surface chemical composition of nine strains of Bacillus subtilis was determined by X-ray photoelectron spectroscopy. Regressions between elemental concentrations and concentrations associated with different components of C1s, N1s, and O1s peaks provided a more precise validation of the procedure used for peak decomposition and allowed the assignment of the peak components to be completed or strengthened. The component of the O1s peak appearing around 531.2 eV was shown to contain a contribution of oxygen from phosphate groups (PO, PO-), the other contribution being due to oxygen involved in amide functions. The surface negative charge may be fully attributed to phosphate groups, despite the observation of two types of zeta potential vs pH curves. The strains exhibiting a sharp variation of the zeta potential (range of -35 to -55 mV) between pH 2 and 4.7 were characterized by a high phosphate surface concentration and by an excess (about 25%) of phosphate with respect to the sum of potassium, an exchangeable cation, and protonated nitrogen, attributed to protein or to alanine involved in teichoic acids.     

Synthesis and antimicrobial activity of some new 1,3,4-thiadiazole and 1,2,4-triazole compounds having a D,L-methionine moiety

New 1,3,4-thiadiazole, 5a-e, and 1,2,4-triazolecompounds 6a-c, containing a D,L-methionine moiety were synthesized by intramolecular cyclization of 1,4-disubstituted thiosemicarbazides 4a-e in acid and alkaline media, respectively. The potential antimicrobial effects of the synthesized compounds were investigated using the Staphylococcus aureus ATCC 25923, Bacillus antracis ATCC 8705, Bacillus cereus ATCC 10987, Sarcina lutea ATCC 9341 and Escherichia coli ATCC 25922 strains. The newly synthesized compounds exhibited promising activities against Bacillus antracis and Bacillus cereus.     

Differentiation of strains from the Bacillus cereus group by RFLP‐PFGE genomic fingerprinting

Bacillus mycoides, Bacillus pseudomycoides, Bacillus weihenstephanensis, Bacillus anthracis, Bacillus thuringiensis, and Bacillus cereus belong to the B. cereus group. The last three species are characterized by different phenotype features and pathogenicity spectrum, but it has been shown that these species are genetically closely related. The macrorestriction analysis of the genomic DNA with the NotI enzyme was used to generate polymorphism of restriction profiles for 39 food‐borne isolates (B. cereus, B. mycoides) and seven reference strains (B. mycoides, B. thuringiensis, B. weihenstephanensis, and B. cereus). The PFGE method was applied to differentiate the examined strains of the B. cereus group. On the basis of the unweighted pair group method with the arithmetic mean method and Dice coefficient, the strains were divided into five clusters (types A–E), and the most numerous group was group A (25 strains). A total of 21 distinct pulsotypes were observed. The RFLP‐PFGE analysis was successfully used for the differentiation and characterization of B. cereus and B. mycoides strains isolated from different food products.     

Location of 43 kD mosquito-larvicidal toxin gene of highly toxic Bacillus sphaericus 10

The direct evidence of the location of the mosquito-larvicidal gene of Bacillus sphaericus 10 (isolated from Jiangsu Province of China) on megaplasmid pFW1 was given by molecular cloning. The clone (pFL109) containing the 1.4 kb HindIII DNA fragment from pFW1 expressed the mosquito-larvicidal toxin protein (43 kD). The location of the gene coding for the 43 kD toxin protein within the XhoI B fragment on the restriction map of pFW1 was confirmed by Southern blotting using the 1.4 kb HindIII DNA fragment as a probe. The non-toxic strains of Bacillus sphaericus were revealed to be 43 kD toxin gene deletion mutants by Southern and Western analyses. The 1.4 kb HindIII fragment of pFL109 can be used as a probe for differentiating the non-toxic strains of Bacillus sphaericus from the toxic ones.     

Direct mass spectrometric analysis of Bacillus spores

Spores from the Bacillus species, B. cereus, B. anthracis, B. thuringensis, B. lichenformis, B. globigi, and B. subtilis, were examined by direct probe mass spectrometry using electron ionization (EI) and positive and negative chemical ionization (CI). Molecular ions from free fatty acids and nucleic acids were observed in the 70eV spectra as were fragments from glycerides. Spectra obtained with isobutane positive chemical ionization (CI(+)) were dominated by ions associated with pyranose compounds such as N-acetylglucosamine (NAG). Unlike the positive ion spectra, the negative ion spectra of the spores were very simple and contained few peaks. The M(-.) ion from dipicolinic acid (DPA) was the base peak in the negative ion spectra of all spore species except those from B. lichenformis. The negative ion of DPA produced such a strong signal that 10(8) colony forming units (CFUs) of B. cereus spores could be detected directly in 0.5 g of ground rice. Principal component analysis (PCA) of the spectra revealed that only CI(+) spectra contained differences that could be used to identify the spectra by species. Differentiation of the CI(+) spectra by PCA was attributed to variances in the peaks associated with the bacterial polymer poly(3-hydroxybutyrate) (PHB) and NAG. Similar differences in PHB and NAG peaks were detected in the CI(+) spectra of a suite of vegetative Bacillus stains grown with various media.     

459—The effect of netropsin on the electrochemical oxidation of DNA at a graphite electrode

The interaction of netropsin with calf thymus, Bacillus cereus and Micrococcus luteus DNAs and with the RNA of phage f2 was studied by means of differential pulse voltammetry at a paraffin-wax-impregnated spectroscopic graphite electrode. It was found that the oxidation voltammetric peaks of double-helical calf thymus and Bacillus cereus DNAs were lowered when netropsin was added to the DNA solution. The peak corresponding to electro-oxidation of adenine residues was lowered more than that corresponding to electro-oxidation of guanine residues. Under the same experimental conditions the oxidation peaks of double-helical Micrococcus luteus DNA, double-helical RNA and thermally denatured samples of all DNAs used were almost uninfluenced by the addition of netropsin. The results observed were explained by (i) decreased flexibility of the segments to which netropsin was bound, and (ii) the specific binding of netropsin to the segments of double-helical DNA rich in adenine thymine pairs.     

Cloth colorization caused by microbial biofilm

In this study, cloth disfeaturement was investigated biologically. To clarify whether or not microbes can cause cloth disfeaturement, and to identify the microbes causing the disfeaturement, worn cloth samples were incubated on sweat-ingredient agar medium. Non-sterilized cloth samples became yellow-colored during incubation, and bacterial strains belonging to the genera Bacillus, Brevibacterium, Kocuria, Micrococcus and Staphylococcus were isolated from the yellow-colored parts. Two major isolates close to the genera Bacillus and Micrococcus were inoculated separately or together on cloth samples to examine whether or not these isolates can cause colorization. When the isolate close to Micrococcus was inoculated on its own or mixed with the isolate close to Bacillus, the samples turned yellow to a greater extent and a biofilm-like structure was observed by SEM on the colored areas. In contrast, the isolate close to Bacillus alone barely caused any colorization, and no biofilm-like structure was observed. From the yellow-colored samples, bacterial strains with the same 16S rRNA gene sequences as those of the inoculated strains were re-isolated. These results strongly suggest that the bacterial strain belonging to genus Micrococcus causes cloth colorization by forming a biofilm structure.     

Characteristics of Bacterial Strains with Desirable Flavor Compounds from Korean Traditional Fermented Soybean Paste (Doenjang)

To identify and analyze the characteristics of the microorganisms involved in the formation of the desirable flavor of Doenjang, a total of 179 strains were isolated from ninety-four Doenjang collected from six regions in South Korea, and fourteen strains were selected through a sensory evaluation of the aroma of each culture. The enzyme activities of amylase, protease and lipase was shown in the various strains. Bacillus sp.-K3, Bacillus sp.-K4 and Bacillus amyloliquefaciens-J2 showed relatively high protease activity, at 317.1 U, 317.3 U and 319.5 U, respectively. The Bacillus sp.-K1 showed the highest lipase activity at 2453.6 U. In the case of amylase, Bacillus subtilis-H6 showed the highest activity at 4105.5 U. The results of the PCA showed that Bacillus subtilis-H2, Bacillus subtilis-H3, and Bacillus sp.-K2 were closely related to the production of 3-hydroxy-2-butanone (23.51%~43.37%), and that Bacillus subtilis-H5 and Bacillus amyloliquefaciens-J2 were significantly associated with the production of phenethyl alcohol (0.39% and 0.37%). The production of peptides was observed to vary among the Bacillus cultures such as Val-Val-Pro-Pro-Phe-Leu and Pro-Ala-Glu-Val-Leu-Asp-Ile. These peptides are precursors of related volatile flavor compounds created in Doenjang via the enzymatic or non-enzymatic route; it is expected that these strains could be used to enhance the flavor of Doenjang.