分离自内蒙古传统肉肠乳酸菌的生长及产酸能力研究

对从内蒙古传统肉肠中分离的8株乳酸菌在不同温度、pH条件下的生长能力以及在不同培养基中的产酸能力进行研究。结果显示,8株菌株在不同温度及不同pH条件下均能够生长,在30℃及pH6.5的条件下生长能力最强。8株乳酸菌在MRS液体培养基、MRS+6%NaCl+150mg/kgNaNO2培养基及模拟肉汤培养基中培养1～13d的产酸能力基本一致,在不同培养基中均有很强的产酸能力,所有菌株在培养24h后pH均迅速下降至4.2以下,此后逐渐趋于平缓。     

8株窖泥链霉菌对酸、乙醇的适应性研究

对分离自窖泥的8株放线菌进行鉴定,并考察其对窖泥环境中pH值、乙醇的耐受性.采用ISP2液体培养基在pH值2.0～3.5、乙醇浓度3%vol ～6%vol条件下培养链霉菌菌株,结果显示,分属于链霉菌属的8个种的8株放线菌均不能耐受pH值2.0及6%vol的乙醇浓度,均能耐受pH值3.5及3%vol的乙醇浓度,5株链霉菌在pH值3.0时可以生长,2株链霉菌可耐受5%vol乙醇,说明分离自窖泥的多数链霉菌对窖泥环境的适应能力较好,但不同种链霉菌的适应能力存在差异,窖泥环境在长期生产过程中对链霉菌属菌株具有一定的选择驯化作用.     

Aciduric, pH-Elevating Bacillus which Cause Noneffervescent Spoilage of Underprocessed Tomatoes

In the preliminary phase of this study, a selective isolation medium was developed. Using the new medium, 24 strains of Bacillus Spp. that elevate tomato juice pH were isolated from garden soil or natural vegetative materials. Two jars of home-canned, water-bathed tomatoes contained sporeformers which produced noneffervescent spoilage. All strains were morphologically and physiologically different from 2 flat-sour strains of B. coagulans and B. licheniformis strains, but similar to a previous isolate from home-canned, spoiled green beans that elevated pH. The new medium may have future applications in isolation and enumeration of other acidurics including yeast-like microorganisms.     

Inhibition of Listeria monocytogenes by bovicin HC5, a bacteriocin produced by Streptococcus bovis HC5

Cattle can be infected with Listeria monocytogenes by consuming contaminated plant materials, soil or silage, and farmers have sought ways of preventing this contamination. Recent work indicated that Streptococcus bovis HC5 produced a bacteriocin (bovicin HC5) that could inhibit a variety of gram-positive bacteria, and we examined the ability of bovicin HC5 to inhibit 10 strains of L. monocytogenes that had been isolated from plant materials, soil, silage and infected cattle. Growth experiments indicated that all of the L. monocytogenes strains were inhibited by 100 activity units (AU) of bovicin HC5 ml(-1). L. monocytogenes cultures that were transferred with sublethal doses (12.5 AU ml(-1)) could be adapted in stepwise fashion to higher doses of bovicin HC5. However, even 'adapted' cultures did not grow if 400 AU ml(-1) was added. The effect of bovicin HC5 on L. monocytogenes was bactericidal, and viability decreased 5-7 logs after only 2 h of exposure. Bovicin HC5 caused a nearly complete efflux of intracellular potassium in 15 min but only if the pH was less than 6.0. When the pH was greater than 6.0, the cells maintained their potassium pool. L. monocytogenes cells that were acid-adapted (final pH of 4.6) were as sensitive to bovicin HC5 as those that were not acid-adapted (final pH of 6.3). These results support the idea that bovicin HC5 could be effective in controlling listeria in contaminated silages.     

Isolation and Screening of Lipase-Producing Fungi with Hydrolytic Activity

Lipases are enzymes that can be secreted by several microorganisms, making interesting the biodiversity exploration for searching new microorganisms able to produce these enzymes. Many agro-industrial residues can be used as potential substrates for production of enzymes. The main objective of this work was the isolation and screening of microorganisms with potential to produce lipases. Among 24 fungi, five were selected as good lipase producers using tributyrin on agar plates and solid state fermentation of soybean bran. Two of them were isolated from soil samples, another two from soybean bran, and one from dairy products. These fungi were identified by microcultivation technique as from Penicillium and Aspergillus genera. Through random amplified polymorphic DNA technique, the most promising strains could be genetically discriminated, selecting two fungi as good lipase producers but genetically different. One isolated from soybean bran could hydrolyze efficiently triglycerides with fatty acids with different chain length. Another isolated from dairy products was only effective to hydrolyze triglycerides with long-chain fatty acids. Two distinct groups could be verified by means of this technique, comprising the most productive strains and the lowest or nonproductive ones in terms of hydrolytic activity.     

葡萄酒中植物乳杆菌的鉴定及其耐受性分析

本论文对4株分离自甘肃、宁夏产区葡萄酒中的乳杆菌进行鉴定并通过调整改良MRS培养基分析植物乳杆菌对酒精浓度、pH和SO2浓度的耐受性.结果表明:16S rDNA鉴定得到3株植物乳杆菌,在单一因素影响下,3株菌在pH 3.0条件下有良好生长,在16％vol酒精浓度可生长,110mg/L SO2浓度下可生长.在综合因素影响...     

Research on some factors influencing acid and exopolysaccharide produced by dairy propionibacterium strains isolated from traditional homemade Turkish cheeses

In this study, a total of 32 isolated strains and 5 reference strains of dairy propionibacteria were analyzed for acid and exopolysaccharide (EPS) production in skim milk and yeast extract-lactate broth (YEL) media in order to investigate the physiological background and preservative role of acid and EPS. The effects of final culture pH and optical density on acid and EPS production were also determined. On average, all strains produced more acid and reached lower final pH values in skim milk than in YEL medium. While the correlations obtained between the acid produced by propionibacterium strains and their final culture pH in skim milk medium were significant (P < 0.01), no correlations were found between optical density, final pH, and produced acid in YEL medium. Sixteen isolated and five reference strains of propionibacteria were tested further for the ability to produce propionic and acetic acids. On average, Propionibacterium freudenreichii subsp. shermanii and P. freudenreichii subsp. freudenreichii strains produced higher amounts of propionic and acetic acids than did Propionibacterium jensenii in YEL medium. The acid produced by these strains may be used as a preservative in the food industry for replacement or reduction of the increasing use of chemical additives. The EPS production by propionibacterium strains during growth in YEL medium was 72 to 168 mg/liter, while in skim milk it was 94 to 359 mg/liter. The monomer compositions of the EPSs formed by the six selected dairy propionibacteria strains were analyzed. The EPSs may have applications as food grade additives and viscosity-stabilizing agents.     

刺葡萄园土壤酿酒酵母的筛选及耐受性分析

从铜仁市刺葡萄园采集土样,采用涂布平板法、平板划线法、酵母浸出粉胨葡萄糖（YPD）培养基分离、纯化酵母,通过WL营养琼脂培养基筛选酿酒酵母（Saccharomyces cerevisiae）,并对其乙醇、糖、酸、温度及SO2耐受性进行分析。结果表明,共获得10株酵母菌株,其中菌株TR-2、TR-3、TR-6、TR-7、TR-10为酿酒酵母（Saccharomyces cerevisiae）,且菌株TR-6、TR-10耐受性较好,均分别能在乙醇体积分数为16%、葡萄糖质量浓度为500 g/L、柠檬酸质量浓度为30 g/L、SO2质量浓度为250 mg/L的YPD液体培养基和高温45 ℃、低温5 ℃条件下生长繁殖。     

水晶葡萄酿酒酵母菌的分离筛选及酿酒性能研究

以水晶葡萄为原料,通过杜氏管产气试验、耐受性试验分离筛选优良酿酒酵母（Saccharomyces cerevisiae）,采用分子生物学技术对其进行鉴定,并研究其酿酒性能。结果表明,筛选出两株优良酵母,分别命名为SJJM-7和SJJM-18;两株菌对糖、低pH值、乙醇和SO2的耐受性较强,均能在50%糖度、12%vol乙醇及200 mg/L SO2的培养基中生长并发酵产气;在pH值2.0的培养基中培养2 d,菌体存活率均＞20%;菌株SJJM-7和SJJM-18均被鉴定为酿酒酵母（S. cerevisiae）;利用这两株菌株发酵水晶葡萄汁后,菌株SJJM-7和SJJM-18的酿酒性能（澄清度、挥发酸含量、残糖量及酒精度）优于进口商品酵母菌株LA-PE,在生产水晶葡萄酒方面具有一定的研究意义和应用价值。     

除膻菌株分离鉴定及其对膻味脂肪酸降解能力的研究

为了分离筛选出能作用于膻味脂肪酸的微生物,从火腿和土壤中分离出11株菌,这11株菌均能对羊油脂进行水解。通过形态学、生理生化特征鉴定及16S rRNA基因序列和ITS基因序列分子生物学鉴定,确定为6株细菌和5株霉菌。分别将11株菌接种到加入4-甲基辛酸和4-乙基辛酸的液体培养基进行发酵,发现4-甲基辛酸的减少量达到30%～70%,4-乙基辛酸减少量达到10%～70%。这11株菌对膻味脂肪酸具有不同程度的降解作用,该研究结果可为微生物羊肉除膻提供理论基础。     

Multiple tolerance of Rhodotorula glutinis R-1 to acid, aluminum ion and manganese ion, and its unusual ability of neutralizing acidic medium

A red yeast isolated from the acidic water of Kusatsu hot spring could grow in an acidic medium of pH 1.5 and was identified as Rhodotorula glutinis. Electron microscope observations (scanning electron microscopy [SEM] and transmission electron microscopy [TEM]) showed that cell envelope became wrinkled and thick as the pH values of media became lower. The cell membrane grown at pH 1.5 was about four times as thick as that grown at pH 6.0. It was suggested that the change of cell envelope plays an important role in the acid tolerance. Cellular proteins at pH 1.5 appeared to be different from those at pH 6.0 and the amounts of phospholipids and non-phospholipids increased and decreased under low pH conditions, respectively. The acid-tolerant yeast also showed strong resistance to both aluminum and manganese ions. An acidic medium (pH 3.0) containing these ions (100 mM) was shifted to neutral pH by long-term cultivation of the red yeast, suggesting the potential of using this yeast in the bioremediation of acidic soil containing these ions at a high level.     

浓香型白酒酿造过程中一株产阿魏酸酯酶菌株的筛选和鉴定

本研究分别从浓香型白酒的大曲、窖泥和糟醅中筛选出一株产阿魏酸酯酶的细菌,并对其生理生化特性进行了研究。通过平板划线对目的菌株进行了分离纯化,再根据形态特征和16S rRNA同源序列分析对分离菌株进行鉴定。结果表明,所分离筛选的产阿魏酸酯酶的菌株为考氏科萨克氏菌（Kosakonia cowani）,产阿魏酸酶活为25.85 U/L。生物学特性为:菌株在16 h时生物量达到最大,最适生长温度为32℃,最适生长培养基初始pH为5,在NaCl浓度1%~9%、酒精浓度1%~4%范围内可以正常生长。     

低磷胁迫对大豆根系生长特性及分泌H~＋和有机酸的影响

以不同基因型大豆nf37和冀黄13为材料,溶液培养法研究大豆根系周围的酸化现象,并通过对大豆根干重、根冠比以及植株中磷含量的测定来探讨不同基因型大豆对枸溶性磷肥的利用效率。结果表明,低磷胁迫下,不同基因型大豆的根系均能主动向外界环境分泌H＋;经HPLC分析得出,柠檬酸、草酸、酒石酸和苹果酸是主要分泌的有机酸;当向培养介质中添加枸溶性磷肥后,不同基因型大豆均可有效利用这一难溶性磷肥。无论是H＋分泌量、有机酸分泌量还是对枸溶性磷肥的利用效率,耐低磷基因型大豆（nf37）都显著高于磷敏感基因型大豆（冀黄13）。表明,低磷胁迫均导致不同基因型大豆根系向介质中分泌H＋和有机酸,同时还诱导大豆根系的加速生长,各项指标在耐低磷和磷敏感大豆基因型之间表现出显著差异,这可能是不同基因型大豆对枸溶性磷肥吸收、利用效率不同的原因。     

耐超高压胁迫副溶血性弧菌的逆境耐受性

目的：探讨水产品中耐超高压胁迫的副溶血性弧菌对高压及其他逆境环境的耐受性。方法：以80～250 MPa超高压处理原始敏感菌株（Vibrio. parahaemolyticus ZJGSMC001）,筛选得到耐高压菌株（V. parahaemolyticus ZJGSPR001）,以其他逆境处理,分析二者对高压和其他逆境的耐受性差异。结果：以250 MPa压力胁迫处理,耐压菌株存活量比原始菌株高2（lg（CFU/mL））。3 ℃以下原始菌株生长速率为负值,45 ℃以上原始菌株不能存活,耐压菌株则生长良好,1 ℃和48 ℃时仍可存活。在NaCl质量浓度高达11.5 g/100 mL时,原始菌株为负生长,耐压菌株仍能生长。耐压菌株对有机溶剂和有机酸的耐受性增强,其中乙醇体积分数12%、丙酮体积分数9%、甲苯体积分数0.75%、柠檬酸3 mg/mL和乳酸体积分数1.5%时,原始菌株全部致死,耐压菌株仍存活。结论：原始菌株对压力较敏感,而耐压菌株经超高压胁迫处理后,除对高压的耐受能力提高外,对其他逆境（如温度、氯化钠、有机溶剂、有机酸）的耐受性也有所增强。     

Isolation and characterization of Kluyveromyces marxianus mutants deficient in malate transport

In malic acid-grown cells of the strains ATCC 10022 and KMS3 of Kluyveromyces marxianus the transport of malic acid occurred by a malate-proton symport, which accepted l-malic, d-malic, succinic and fumaric acids, but not tartaric, malonic or maleic acids. The system was inducible and subjected to glucose repression. Mutants of the strain KMS3, unable to grow in a medium with malic acid, were isolated and checked for their capacity to utilize several carbon sources and to transport dicarboxylic acids by the malate-proton symport. Two distinct clones affected on malate transport were obtained. Both were able to grow on a medium with glycerol or ethanol but not with dl-malic, succinic, oxoglutaric and oxaloacetic acids as the sole carbon and energy sources. However, while one of the mutants (Mal7) displayed activity levels for the enzymes malate dehydrogenase, isocitrate lyase, and phosphoenolpyruvate carboxykinase similar to those of the wild strain, in the other mutant type (Mal6) the activities for the same enzymes were significantly reduced. Plasma membranes from derepressed cells of the wild strain and of the mutants Mal6 and Mal7 were isolated and the protein analysed by SDS–PAGE. The electrophoretic patterns of these preparations differed in a polypeptide with an apparent molecular mass of about 28 kDa, which was absent only in the mutant Mal7. The results indicated that Mal7 can be affected in a gene that encodes a malate carrier in K. marxianus. © 1998 John Wiley & Sons, Ltd.     

分离自藏灵菇的乳酸菌的益生特性

从藏灵菇中分离纯化5株乳酸菌,初步鉴定2株为嗜酸乳杆菌,3株为乳酸乳球菌。选取其中2株菌研究其益生特性。结果表明,从藏灵菇中分离出的乳酸菌具有良好的益生特性,2株乳酸菌在pH值为4～6可生长良好;耐热范围为30～60℃;胆盐耐受性为0.1%～0.5%;发酵液对金黄色葡萄球菌、沙门氏菌、大肠杆菌等肠道病原菌有抑制作用;对抗生素有不同程度的耐药性。     

Existence of an iron-oxidizing bacterium Acidithiobacillus ferrooxidans resistant to organomercurial compounds

Acidithiobacillus ferrooxidans MON-1 which is highly resistant to Hg2+ could grow in a ferrous sulfate medium (pH 2.5) with 0.1 microM p-chloromercuribenzoic acid (PCMB) with a lag time of 2 d. In contrast, A. ferrooxidans AP19-3 which is sensitive to Hg2+ did not grow in the medium. Nine strains of A. ferrooxidans, including seven strains of the American Type Culture Collection grew in the medium with a lag time ranging from 5 to 12 d. The resting cells of MON-1, which has NADPH-dependent mercuric reductase activity, could volatilize Hg0 when incubated in acidic water (pH 3.0) containing 0.1 microM PCMB. However, the resting cells of AP19-3, which has a similar level of NADPH-dependent mercuric reductase activity compared with MON-1, did not volatilize Hg0 from the reaction mixture with 0.1 microM PCMB. The activity level of the 11 strains of A. ferrooxidans to volatilize Hg0 from PCMB corresponded well with the level of growth inhibition by PCMB observed in the growth experiments. The resting cells of MON-1 volatilized Hg0 from phenylmercury acetate (PMA) and methylmercury chloride (MMC) as well as PCMB. The cytosol prepared from MON-1 could volatilize Hg0 from PCMB (0.015 nmol mg(-1) h(-1)), PMA (0.33 nmol mg(-1) h(-1)) and MMC (0.005 nmol mg(-1) h(-1)) in the presence of NADPH and beta-mercaptoethanol.     

Selection of Yeasts as Starter Cultures for Table Olives

Ninety‐nine yeasts were isolated from Bella di Cerignola table olives; first, the strains were studied in relation to their ability to produce biogenic amines in a laboratory medium and 49 strains were positive to this assay and cut off from the research. The remaining 50 strains were characterized for their enzymatic traits (β‐glucosidase, catalase, pectolytic, xylanolytic, and lipolytic activities) and for their ability to grow at different temperatures, pHs, with salt or lactic/acetic acids added. Data were used for the evaluation of growth index and submitted to cluster and principal component analyses to choose the most promising 4 strains. In the final step of the research, the strains were inoculated as a cocktail in a model brine, containing different amounts of salt (4% to 12%) and glucose (0% to 3%), and adjusted to different pHs (4.0 to 9.0). Data analysis through a multiple regression procedure highlighted that salt, glucose, and pH acted in a different way within the storage and NaCl affected yeast growth only for few days, and then glucose and pH played a major role. Practical Application Olive fermentation relies upon a complex microflora, including lactic acid bacteria and yeasts; the selection of suitable strains of yeasts intended as starter cultures, as well as their inoculation in brines, could improve the fermentation.     

基于ITS4/5 rRNA区序列对不同时期大曲中霉菌的分离与鉴定

利用大曲作为糖化发酵剂是中国传统白酒主要的工艺特点之一。大曲中的微生物组成十分丰富包括各种种类的霉菌、酵母以及细菌,这些复杂的微生物体系为白酒的发酵提供了必要的微生物、酶以及风味物质。其中霉菌作为酒类发酵生产中必不可少的微生物,在大曲发酵过程中能够分泌一些糖化酶和蛋白酶等多种酶类以及有机酸等多种代谢产物,对大曲质量好坏起着重要作用。为了探究大曲中霉菌功能,本文对不同时期大曲中分离的霉菌采用ITS4/5 rRNA区序列进行分析比对,共分离鉴定了193株霉菌,分属于13个种。主要为红曲(Aspergillus ruber),米根霉(Rhizopus oryzae),微小根毛霉(Rhizomucor pusillus),Rhizopus azygosporus,烟曲霉(Aspergillus fumigatus),嗜热子囊菌(Thermomyces lanuginosus),谢瓦氏曲霉(Aspergillus salwaensis),Aspergillus chevalieri,米曲霉(Aspergillus oryzae)等,并构建了M-L系统树。根据这些分离鉴定的结果初步探究出大曲生产过程中不同时期霉菌的组成和变化规律。这些结果为进一步研究中国传统白酒的酿造微生物奠定了一定的基础。     

Growth and survival of various strains of enterohemorrhagic Escherichia coli in hydrochloric and acetic acid

Nineteen strains of enterohemorrhagic Escherichia coli isolated from humans and foods were examined for their ability to grow and survive at low pH in organic (acetic) and mineral (HCl) acids. Strains were subcultured in tryptic soy broth adjusted to various pH values (3.75 to 4.75 for HCl and 4.75 to 5.75 for acetic acid) and incubated for 72 h at 37 degrees C to determine the minimum growth pH value. Minimum pH values for growth of 4.25 and 5.5 were found for HCl and acetic acid, respectively. Strains were also exposed to pH 2.0 (HCl) and pH 4.0 (acetic acid) for up to 24 h at 37 degrees C to assess their ability to survive. HCl was a more effective inhibitor after 6 h of exposure, whereas acetic acid was more effective after 24 h. Outbreak strains survived acid treatment significantly (P < or = 0.05) better than strains isolated from fermented or high-pH foods or animal or human isolates. Significant (P < or = 0.05) differences among serotypes and between O157:H7 and other serotypes were apparent after 3 or 6 h of exposure to acids.