两歧双歧杆菌86321生长特性的研究

目的研究两歧双歧杆菌86321的生长特性,为该菌生理功能研究和高效发酵剂的研制提供理论依据。方法通过生长曲线、产酸量、最适厌氧方式、最适pH、最适培养温度及最适接种量等一系列实验,对两歧双歧杆菌86321进行生长特性的研究。结果两歧双歧杆菌86321在BL培养基中培养时间可缩短至16 h,最高活菌数的lg值达到9.5;其最适厌氧方式为自然厌氧法或密封法,装液量视实际情况而定;在pH7.08.0生长良好,最适初始pH为8.0;在3742℃生长良好,最适温度为37℃;综合总菌量和生产成本,确定最适接种量为7%（v/v）。结论用BL培养基可以大大提高两歧双歧杆菌86321的产量。细菌产量的高低和发酵速度的快慢与菌种活力、厌氧方式、培养温度及pH等因素密切相关。     

短乳杆菌(Lactobacillus brevis)去除亚硝酸盐的研究

短乳杆菌有较强去除亚硝酸盐能力 ,亚硝酸盐含量在 2 5 0mg L以内 ,接种短乳杆菌48h亚硝酸盐全部去除。短乳杆菌处理亚硝酸盐主要处于亚硝酸还原酶还原亚硝酸盐阶段。短乳杆菌去除亚硝酸盐的最适pH值为 5.0～ 6.0 ,最适温度为 3 0℃ ;在其它条件不变的情况下 ,发酵初期 (1 0～ 2 6h)亚硝酸盐去除量随接种量的增加而增加 ,最适接种量为5 %。亚硝酸盐含量在 2 0 0mg L以内 ,短乳杆菌对亚硝酸盐的去除量与底物浓度有极显著的线性关系。     

樟树内生细菌EBS05发酵条件的研究

枯草芽胞杆菌EBS05是从樟树中分离的1株对多种植物病原真菌具有拮抗作用的内生细菌。以小麦纹枯病菌为靶标菌,通过单因素试验和正交设计试验对其发酵条件进行了优化。结果表明,内生细菌EBS05适宜的发酵培养基主要营养成分的组成和配比分别为可溶性淀粉3%、蛋白胨2%、NaCl 0.25%。最佳发酵条件为:初始pH5~9,最适温度34℃,装液量25 mL/250 mL三角瓶,接种量3%,发酵时间72 h。     

短乳杆菌(Lactobacillus brevis)去除亚硝酸盐的研究

短乳杆菌有较强去除亚硝酸盐能力,亚硝酸盐含量在250mg／L以内,接种短乳杆菌48h亚硝酸盐全部去除。短乳杆菌处理亚硝酸盐主要处于亚硝酸还原酶还原亚硝酸盐阶段。短乳杆菌去除亚硝酸盐的最适pH值为5．0～6．0,最适温度为30℃;在其它条件不变的情况下,发酵初期(10～26h)亚硝酸盐去除量随接种量的增加而增加,最适接种量为5％。亚硝酸盐含量在200mg／L以内,短乳杆菌对亚硝酸盐的去除量与底物浓度有极显著的线性关系。     

产α-葡萄糖苷酶抑制剂乳酸菌的筛选及发酵条件优化

以改良的体外模型为检测手段,测试了不同乳酸菌发酵大豆豆浆的产物对麦芽糖酶的抑制作用。在测试过的乳酸菌中,以植物乳杆菌ST-Ⅲ(Lactobacillus plantarum ST-Ⅲ)在37℃发酵大豆豆浆获得的发酵产物对麦芽糖酶的抑制效果最强。随后,考察了接种量、豆浆固形物含量、发酵温度对植物乳杆菌ST-Ⅲ发酵豆浆对麦芽糖酶抑制活性的影响。结果表明,植物乳杆菌ST-Ⅲ发酵大豆豆浆产生麦芽糖酶抑制物的最适条件分别为接种量2%(v/v)、豆浆固形物含量5%(w/v)、发酵温度37℃。在优化条件下,发酵8 h获得的发酵豆浆对麦芽糖酶的抑制率达到80%。     

益生菌体外增殖因子的初步研究

目的研究单糖、pH、温度及时间对青春双歧杆菌、长双歧杆菌和类干酪乳杆菌体外增殖的影响。方法用甘露糖、半乳糖、山梨醇及果糖代替MRS中的葡萄糖,筛选出每种细菌的最适碳源。以此为基础,选择其最佳初始pH、培养温度、碳源添加量及培养时间。结果青春双歧杆菌、长双歧杆菌和类干酪乳杆菌的最适碳源分别为葡萄糖、甘露糖和半乳糖;最佳初始pH为6.0、7.0和6.0;培养温度为42、30和30℃;碳源添加量为20、15和25 g/L;培养时间都为28-48 h。结论益生菌具有不同的最适增殖条件,本文研究结果为优化益生菌的生长条件提供了基础数据。     

植物乳杆菌R260产细菌素发酵条件的研究

目的 获取植物乳杆菌R260产细菌素的最佳发酵条件.方法用琼脂扩散法测定发酵液对苏云金芽胞杆菌的抑菌效价.结果 产细菌素的最佳培养基是MRS培养基,最适起始Ph为6.5,最适接种量和接种种龄分别为3%和12 h,产细菌素最适发酵温度和时间分别为30℃和20 h：细菌素在对数期开始产生,稳定期产量达到最大值.结论 通过优化发酵条件提高了细菌素的产量,达1656 IU/ml.     

红酵母NZ-01发酵条件的优化

以红酵母菌株NZ-01为试验菌株,研究其发酵工艺与中试生产。采用摇瓶发酵优化的方式,研究培养基组分与发酵工艺条件对该菌发酵的影响,并进行中试放大生产。结果显示,该菌最适生长培养基组分为葡萄糖10g/L,蔗糖10g/L,酵母膏10g/L,牛肉膏2.5g/L;色素合成最适培养基组分为葡萄糖15g/L,蔗糖10g/L,酵母膏2.5g/L,牛肉膏5g/L。最适生长起始pH值为6.0,最适接种量为8%,生长周期为44h;最适色素合成起始pH值为7.0,最适色素合成接种量为8%,色素合成周期为48h。发酵优化后的色素产量3.88μg/mL较优化前1.71μg/mL提高了127%。中试产量达3.05μg/mL。红酵母菌NZ-01优化后的发酵条件可以应用于中试生产虾青素,有规模化生产应用潜力。     

混合菌固体发酵花生粕的工艺优化

本实验选用符合《饲料添加剂品种目录》的植物乳杆菌(Lactobacillus plantarum)EM1、酿酒酵母(Saccharomyces cerevisiae)JM、枯草芽孢杆菌(Bacillus subtilis)BW2作为发酵菌株对花生粕进行固体发酵,以多肽和总酸含量为指标,通过单因素实验及正交试验对植物乳杆菌、酿酒酵母、枯草芽孢杆菌接种量,发酵温度,发酵时间和料液比进行优化。确定工艺参数为:植物乳杆菌接种量5%,酿酒酵母接种量9%,枯草芽孢杆菌接种量9%,料液比1∶1.2,发酵温度37℃,发酵时间48 h。在此条件下发酵花生粕,多肽和总酸含量分别为18.89%±0.35%和9.12%±0.23%,较优化前分别提高33.78%和24.45%,提高幅度较大,可见优化后工艺稳定且重复性较好。     

一株中温淀粉酶菌株的分离鉴定及其产酶条件分析

利用固体淀粉筛选培养基,从安阳市郊区面粉厂附近的土壤里分离筛选出1株产淀粉酶的菌株,编号为MF-3-2.经过菌株形态、革兰氏染色、16S rDNA鉴定及系统进化树分析,初步确定其为枯草芽孢杆菌(Bacillus subtilis).摇瓶培养后对其酶学性质研究发现,该菌株淀粉酶的最适温度为65℃,最适pH值为6.0,在pH值4.8～6.0范围内仍能残余70％以上的酶活力.该菌株的最适生长温度为40℃,最适生长pH值为6.5.产酶条件优化结果表明:最适碳源为马铃薯淀粉,最适氮源为豆粕粉,最适碳氮比为1∶15,发酵温度30℃,发酵pH值6.0,装液量10％,种龄10h,接种量5％,转速200 r/min,48 h达到产酶高峰.通过发酵产酶条件优化,其淀粉酶活性达到86.8 U/mL,是优化前的35倍.另外,在酸性条件下还具有较好的活性.因此,该菌株的淀粉酶具有潜在的工业应用前景.     

植物乳杆菌粘附性与其表面特征关系的探究

本文通过16s rDNA鉴定获得4株植物乳杆菌,并以HT29细胞为体外黏附筛选模型,进一步探讨了这些菌株粘附能力与表面疏水性、自聚共聚能力等表型特征的相关性。结果表明,植物乳杆菌AR326菌株对HT29细胞的粘附性最强,并显示高度的自聚性(25%)和共聚性(25%),但其表面疏水性偏低(15%);通过相关性分析发现,植物乳杆菌的自聚性和共聚性与HT29细胞粘附性呈显著相关性(r=1.0和0.8,p0.05),但表面疏水性、自凝聚性和共聚性两两之间并无显著相关性(p0.05)。本研究结果为建立快速筛选高粘附性植物乳杆菌的方法及其菌株在体内定植和分布研究提供一定参考依据。     

固定化植物乳杆菌的制备及其发酵条件优化

采用海藻酸钠包埋植物乳杆菌并通过测定固定化细胞发酵清液的抑菌效果,优化得到的固定化最佳工艺条件为:海藻酸钠浓度为3%,CaCl2浓度为1.5%,菌悬液体积为3.5 mL(4.0×108 cfu/mL).固定化细胞重复发酵多批次效果良好.固定化细胞发酵条件优化结果表明:最适pH为7.0,最适温度为36℃,培养基中添加0....     

Screening of lactic starter from Tunisian fermented vegetables and application for the improvement of caper (Capparis spinosa) fermentation through an experimental factorial design

This study aims at designing a lactic starter for caper fermentation isolated from Tunisian fermented vegetables to improve the process and produce consistent and high-quality product. In this study, the lactic starter was isolated by exploring the lactic acid bacteria (LAB) of Tunisian artisanal fermented vegetables. Identification was carried out by partial 16S rRNA gene sequencing. Screening was based on salt tolerance and antagonistic activities against Escherichia coli ATCC 10536 and Enterococcus faecalis ATCC 10541. Caper fermentation was optimized through a full factorial experimental design (23), by exploring three factors: starter inoculum size, NaCl concentration, and acetate content. Differences in pH values, Total aerobic mesophilic bacteria and LAB counts between the beginning and end of fermentation are selected as responses and corresponding regression coefficients were calculated. The lactic microbiota is mainly represented by Lactobacillus plantarum group. Based on salt tolerance and antimicrobial activity, the strain Lactobacillus plantarum F3 was selected as starter for caper fermentation. The effect of NaCl concentration, acetate content, and inoculum size on acidity, total aerobic mesophilic bacteria count, and LAB count after 1 week and 1 month of caper fermentation was studied. Depending on the fermentation time, either 1 week or 1 month, the initial conditions should comprise 0% acetate, 108 CFU/mL inoculum, and 5% NaCl for 1 week against 5% acetate, 107 CFU/mL inoculum, and 10% NaCl for 1 month lasting caper fermentation. A protocol for caper fermentation was set up ensuring hygienic quality and LAB viability. Lb. plantarum F3 was selected as lactic starter for caper fermentation, and initial fermentation conditions were optimized through a full factorial design. This work has shown loss in LAB viability after 1 week of fermentation. Based on results obtained, an optimized fermentation protocol was set up. This protocol ensures LAB survival and high hygienic quality of the product.     

一株植物乳酸杆菌的高密度发酵

目的研究一株植物乳酸杆菌的高密度发酵。方法通过单因素实验来确定此植物乳酸杆菌的最适生长温度、pH、碳源、氮源、缓冲盐等。结果最适生长温度是37℃、起始pH6.4、最适碳源为葡萄糖、最适氮源为牛肉膏,通过对缓冲盐的选择最终确定NaAc：CaCO3比为0.5：1.5;控制发酵条件,结合优化培养基,可使发酵后的培养液达到2.75×10^10CFU/ml。结论该缓冲盐能够有效的缓解发酵液pH的下降,延长对数生长期,使活菌数提高1倍,适合高密度发酵培养。     

Optimum bacteriocin production by Lactobacillus plantarum 17.2b requires absence of NaCl and apparently follows a mixed metabolite kinetics

Bacteriocins from lactic acid bacteria are ribosomally synthesized anti-microbial compounds that may find applications from food preservation to healthcare. Food preservation, using in situ bacteriocin production is the most obvious and simple. Frequently, the best conditions for bacteriocin production are those prevailing during food fermentation but a better understanding of the relationship between growth and bacteriocin production is required. In this work, we evaluate the effects of some environmental factors on bacteriocin production by Lactobacillus plantarum 17.2b. A first screening design showed that NaCl, temperature, pH and the type and concentration of carbon and nitrogen sources were most influents. A moderate stimulatory effect of ethanol and oleuropein was also registered. Two consecutive central composite designs were used to examine the effect of the selected variables and to compute its optimum. The evolution of changes produced by the alterations in environmental factors was further examined trough perturbation plots. Bacteriocin production by L. plantarum 17.2b was very sensitive to environmental conditions and uncoupled from growth. Maximum production required suboptimal growth temperatures, pH values above growth's optimum and no NaCl. A preliminary approach to kinetics showed that bacteriocin production by this strain apparently follows mixed metabolite kinetics.     

Citrate metabolism by Lactobacillus plantarum isolated from orange juice

The behaviour of Strains of Lactobacillus plantarum isolated from fermented orange juice and Lact. plantarum DSM 20174 was studied in the presence of citrate. When used as sole carbon source, citrate scarcely supported the growth of the bacteria. It was shown to enhance the growth of Lact. plantarum in glucose media. Under acid conditions (pH 4·0–5·0), 1 mol of citrate yielded 1·7 mol of acetate as sole major final metabolite with release of CO₂ in the gas phase.     

益生乳酸菌Lactobacillus casei Zhang和Lactobacillus plantarum P8对全价饲料pH及微生物类群变化的研究

研究了益生乳酸菌干酪乳杆菌Zhang(Lactobacillus casei Zhang)和植物乳杆菌P8(Lactobacillus planta-rum P8)对全价饲料pH及微生物类群变化的影响。分别将L.casei Zhang、L.plantarum P8单一菌种及复合菌种(11)以6.30 lg cfu/g的接种总量发酵全价饲料,测定25℃10 d发酵期间全价饲料pH和微生物类群的变化,应用选择培养基测定发酵饲料中的乳酸菌及杂菌(酵母菌、霉菌、大肠菌群、芽胞杆菌和梭状芽胞杆菌)的动态变化,应用RT-PCR技术测定试验组中的L.casei Zhang和L.plantarum P8的动态变化。结果显示,试验组pH下降显著,发酵10 d时,L.casei Zhang、L.plantarum P8单一菌种和复合菌种发酵饲料的pH分别为4.23、4.24和4.22,显著低于对照组(P0.05);L.casei Zhang、L.plantarum P8单一菌种和复合菌种发酵饲料中的L.casei Zhang、L.plantarum P8活菌数分别为8.91、8.89、6.58和8.69 lg cfu/g。发酵期间,试验组中酵母菌、霉菌、大肠菌群、芽胞杆菌及梭状芽胞杆菌活菌数显著低于对照组(P0.05),其中L.plantarum P8单一菌种发酵和复合菌种发酵对杂菌抑制效果显著优于L.casei Zhang单一菌种发酵(P0.05)。结果表明,全价饲料经L.casei Zhang、L.plantarum P8发酵可以显著降低其pH,抑制其中杂菌的生长,同时L.casei Zhang、L.plantarum P8在饲料中具有良好的稳定性。     

一株广谱抑菌活性乳酸菌的筛选及特性研究

【目的】从贵州剑河采集的传统自然发酵豆酱中分离筛选具有广谱抑菌效果的乳酸菌,并进行肠道益生特性的研究。【方法】通过抑菌试验分离筛选得到菌株DJ-04,对其进行人工胃肠液耐受性、胆盐耐受性和渗透压耐受性的研究,并对其进行生理生化鉴定和16S r RNA鉴定。【结果】菌株DJ-04对大肠杆菌、沙门氏菌、金黄色葡萄球菌、志贺氏菌和铜绿假单胞菌的生长有很好的抑制作用;在p H值为2.5的人工胃液中处理3 h活菌数达到107 CFU/m L以上;在人工肠液中处理3 h活菌数达到108 CFU/m L以上,对人工胃肠液表现出良好的耐受性。能耐受一定浓度的牛胆盐,在质量浓度0.2 g/100 m L的牛胆盐环境中活菌数可达到107 CFU/m L;具有较高的渗透压耐受能力,在Na Cl质量浓度为10 g/100 m L的液体MRS中培养24 h后,活菌数仍在107 CFU/m L以上。经鉴定,DJ-04为植物乳杆菌。【结论】植物乳杆菌DJ-04具有良好的人工胃肠液耐受性以及耐胆盐和耐渗透压能力,具有肠道益生菌的潜能。     

模拟人体胃肠道环境筛选益生乳杆菌

【目的】筛选具有益生特性的乳杆菌作为保健型酸奶的候选菌株。【方法】从健康人肠道和奶豆腐中分离筛选出耐受人工胃液的乳杆菌,对其进行体外益生特性(人工胃肠液耐受性、胆盐耐受性、抑菌活性及胆固醇降解能力)研究。【结果】从在乳杆菌分离培养基上有溶钙圈的41株菌株中筛选出5株耐酸、耐人工胃液较强的菌株,经16S rR NA基因测序鉴定,其中3株为乳杆菌,分别命名为植物乳杆菌Lp MT-3、植物乳杆菌Lp MT-5和唾液乳杆菌LsA F-7。在人工胃液中3株菌的耐受力均强于商品化的对照菌株LGG(鼠李糖乳杆菌GG);转入肠液4 h后直至26 h,Lp MT-5存活率基本稳定在45%左右,仅次于LGG。胆盐浓度为0.10%时,3株乳杆菌的耐胆盐能力均强于LGG;胆盐浓度为0.20%时,Lp MT-3和LsA F-7仍能存活。3株乳杆菌均具有抑菌活性,对粪肠球菌的抑制最明显,其次是金黄色葡萄球菌,对大肠杆菌、沙门氏菌的抑制作用较差。3株乳杆菌对胆固醇的清除效力依次为Lp MT-3LpM T-5Ls AF-7;清除率依次为Ls AF-7Lp MT-3LpM T-5。【结论】筛选出3株适应人体胃肠液环境、耐胆盐、抑菌及降胆固醇活力强的乳杆菌,可作为进一步开发新的益生菌产品和保健型酸奶的菌株。     

Kinetic growth parameters of different amylolytic and non-amylolytic Lactobacillus strains under various salt and pH conditions

Four Lactobacillus species were studied for their ability to grow at high NaCl concentrations and different initial pH values. Lactobacillus plantarum 541 and A6 could ferment glucose and produce lactic acid in the presence of 8% salt in the medium. For strain 541, the specific rate of lactate production (q(lac)) and the yield of lactic acid relative to substrate (Y(p/s)) remained constant, whereas the yield of biomass relative to substrate (Y(x/s)) decreased up to 6% salt. In contrast, for strain A6, Y(p/s) decreased up to 6% salt whereas Y(x/s) did not vary markedly. Combined effects of salt and pH studied through a factorial design did not show significant interaction between salt and pH. The pH was the dominant factor in glucose fermentation for both the strains. Considering overall performance, 4% salt and pH between 6.0 and 6.6 can be taken as appropriate conditions, for the use of both strains as starters in processes where higher salt concentrations are required.