双歧杆菌模拟胃肠环境中抗性的研究

采用PYG培养基,模拟胃肠环境,即低pH值(1．5—4．5),高胆汁酸盐(9．1％-0．4％)对青春双歧杆菌进行抗性研究。同时对肠道致病性大肠埃希菌、福氏志贺菌和金黄色葡萄球菌拮抗性以及对氨苄青霉素、庆大霉素、卡那霉素和氯霉素的耐药性进行研究。结果表明,青春双歧杆菌在pH4．5时有较强的生存能力,4h活菌效可达10^7CFU／m1以上。且能在含0．1％-0．4％的胆汁盐中存活,在0．1％-0．2％时4h活菌总数可达10^5CFU／m1以上。同时对致病性大肠埃希菌、福氏志贺菌和金黄色葡萄球菌具有明显的抑菌作用,且对庆大霉素中度敏感,对氨苄青霉素、卡那霉素和氯霉素有耐受性。     

嗜酸乳杆菌在模拟胃肠环境中抗性的研究

采用MRS培养基,模拟胃肠环境,即低pH值（1.5～4.5）。高胆汁盐（0.1％～0.4％）对嗜酸乳杆菌抗性进行了研究。同时对肠道中致病性大肠杆菌、金黄色葡萄球菌的拮抗特性以及服用抗生素后嗜酸乳杆菌的耐药性进行了研究。结果表明,嗜酸乳杆菌在pH2.5～4.5时具有较强的生存能力,6h活菌数仍达 10⁷cfu/mL以上,pH1.5条件下仍有部分存活。在0.1％～0.3％胆汁盐条件下4h活菌数仍达106cfu/mL以上,且能在0.4％胆汁盐中存活。同时,对致病性大肠杆菌和金黄色葡萄球菌具     

乳酸菌发酵产品的降血压功能及其机制

1概述 血压是目前最为广泛的心血管疾病,据世界卫生组织（WHO）估计,全球患病人数已超过5亿.它是冠心病、脑卒死、心及肾功能衰竭的最主要发病因素,预防和治疗高血压将有助于降低心血管系统疾病的风险.高血压是由多方面因素引发的,如精神、神经、内分泌、遗传及血管紧张素转化酶（Angiotensin Ⅰ-converting enzyme,ACE）活性等,尤以ACE在血压调节过程中起关键作用.如图1所示,一方面,无活性的血管紧张素原在肾素的作用下转化为血管紧张素Ⅰ,血管紧张素Ⅰ在ACE的作用下转化为血管紧张素Ⅱ,血管紧张素Ⅱ能刺激血管收缩使血压升高,同时血管紧张素Ⅱ也能促使醛固酮分泌,直接对肾脏作用,引起纳储量和血容量增加也使血压升高.与此相反,缓激肽是降压物质,它能促使血管扩张和刺激扩血管物质前列腺素的合成增加,二者共同作用使血压下降.而在ACE的作用下,缓激肽分解成失活片断.如果人体内ACE活性过高,就会使血管紧张素Ⅱ生成增加,同时缓激肽被大大破坏,导致血压升高.     

应用于乳酸菌的非抗生素抗性选择标记系统

 乳酸菌是一类重要的安全型微生物,在免疫载体疫苗开发及食品菌株改良等医疗、食品领域均有广泛的应用.非抗生素抗性选择标记是乳酸菌基因工程菌株构建中必不可少的关键组成部分,也是目前乳酸菌研究的前沿和热点.根据筛选时质粒和受体菌之间的表型关系及特征,主要分为显性选择标记、互补型选择标记、显性/互补型选择标记、双质粒选择标记4大类.其中显性选择标记中的细菌素抗性/免疫性选择标记及互补型选择标记中的糖类选择标记均有较大的发展潜力及应用空间;双质粒选择标记系统构建的筛选过程新颖独特,为整个选择标记系统的发展开辟了新的途径及思路.     

一株功能性乳酸菌对胃肠道环境耐受能力的测定

目的对1株具有降胆固醇功能的乳酸菌进行胃肠道环境耐受能力的测定。方法分别测定菌株对胃内酸性和胃蛋白酶的耐受能力以及对小肠内胆盐和胰蛋白酶的耐受能力。结果该菌株对胃肠道有良好的耐受能力。结论本研究为后期菌株在动物及人体内发挥其功能性奠定了实验基础。     

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。     

东北酸菜发酵中几株乳酸菌的筛选

从东北酸菜汁液出发,有目的地筛选到3株菌株,通过对其形态特征、菌落特征及生化特征进行分析可知,3株菌株均为乳杆菌属。对筛选到的乳杆菌属进行酸菜发酵性能研究发现,其中菌株L2在发酵24 h后,产酸量达到2.5%,酸度达到1.73 g乳酸/100 mL,且发酵无异味,口味自然,效果较好。     

30周龄笼养海蓝褐壳蛋鸡盲肠中优良乳酸菌的筛选

目的对笼养蛋鸡盲肠中的优良乳酸菌进行筛选与鉴定。方法以30周龄笼养海蓝褐壳蛋鸡盲肠分离纯化得到10株乳酸菌为试验菌,通过发酵产酸力、耐酸性和耐胆盐的筛选试验,获得产酸能力高、对酸和胆盐有高耐受力的乳酸菌,进行生长曲线和产酸曲线及对抗生素的耐受力的测定,并采用API CHL50试剂条对选出的乳酸菌进行鉴定。结果 10株乳酸菌在发酵起始时间点时p H在6.10~6.40,经过48 h的发酵阶段,发酵液的p H明显降低;酸性环境和胆盐对各菌株存活率均有抑制。CL1、CL12和CL54生长较快,最佳生长和产酸发酵时间是24 h,CL26和CL31生长相对较慢,到32 h时生长曲线达到最高点;对抗生素的耐受力检测结果显示,CL1、CL12和CL54对抗生素的耐受力很高,而CL26和CL31对抗生素的耐受力较弱。结论对CL1、CL12和CL54这三株菌进行种属鉴定。根据API CHL50生化鉴定条说明进行接菌发酵试验,经对照鉴定,CL1为Lactococcus Lactis ssp Lactis1(乳酸乳球菌亚种1),CL12为Pediococcus Acidilactici(乳酸片球菌),CL54为Lactobacillus Brevis1(短乳杆菌1)。     

一株产共轭亚油酸乳酸菌的鉴定及其特性

从酸菜汁中分离筛选到一株产共轭亚油酸(CLA)能力较高的乳酸菌。经鉴定,确定为植物乳杆菌Lactobacliius plantarum。微氧条件可提高CLA的产量,催化亚油酸(LA)生成CLA的酶受着LA的诱导。37℃对细胞生长和CLA生成最为有利。对数生长期为6～12h,18h后进入稳定期。在14～22h,CLA生成量快速增加,24h时达到最高值。该菌的培养物经萃取、甲酯化后,进行了气相色谱分离,生成的CLA产物为c9/t9,c11-CLA和t10,c12-CLA异构体的混合物。     

一株乳酸菌所产胞外多糖对荷瘤小鼠机体免疫功能影响的研究

对一株产胞外多糖（Exopolysaccharide,简称EPS）的乳酸菌Z222菌株的培养条件进行了优化, 其发酵液通过浓缩、除蛋白、脱色、乙醇沉淀、透析、CM纤维素柱、DEAESephadex 离子交换柱和Sephadex G100凝胶柱层析,冷冻干燥后得到一种纤维状白色固体产品EPSⅠ。将该产品对荷肉瘤S180小鼠进行机体免疫功能影响的初步试验,统计学处理结果表明,它对迟发型超敏反应、免疫器官重量和脾细胞抗体形成均有较为明显的影响。EPSⅠ有希望作为一种新的免疫调节剂。     

Lactic acid bacteria in meat fermentation

Abstract The main fermented meat products are fermented sausages in which lactic acid bacteria (LAB) are the essential agents of the ripening process. During indigenous fermentations Lactobacillus curvatus and L. sake are the dominating LAB. Their application as starter organisms ensures the dominance of the starter during the whole ripening process. The suppression of the competing fortuitous LAB depends on the quality of the raw materials and on technological factors. The physiological properties of lactic starters do not suffice to ensure a sensory quality which can be found in traditionally produced dry fermented sausages. Additional activities required are present in micrococci and yeasts which, therefore, are further components of starter culture preparations. Some strains of meat-borne lactobacilli exhibit the essential activities like nitrate reductase, nitrite reductase, catalase, lipase, and protease, respectively. To create the optimal starter cultures composed of lactobacilli, these activities have to be studied and optimized in strains of high competitiveness in the fermenting substrate.     

Characterization of an extracellular factor that stimulates bile salt hydrolase activity in Lactobacillus sp. strain 100–100

Bile salt hydrolase activity in Lactobacillus sp. strain 100-100 is strictly intracellular. The strain produces an extracellular factor that stimulates the intracellular hydrolase activity. The factor is inducible by conjugated bile salts, has an apparent molecular mass over 12 kDa but less than 25 kDa, is stable in air, and resistant to pronase and heat. It is partially extractable into organic solvents and inactivated by a sulphydryl group inhibitor. We postulate that the factor functions by a novel mechanism to facilitate entry of conjugated bile salts into the bacterial cells.     

Lactic acid bacteria in a changing legislative environment

The benefits of using lactic acid bacteria in the food chain, both through direct consumption and production of ingredients, are increasingly recognised by the food industry and consumers alike. The regulatory environment surrounding these products is diverse, covering foods and food ingredients, processing aids, feed additives and dietary supplements. On a global basis, there are different approaches taken by the various regulatory authorities. While in Europe, the national legislation is gradually being harmonised, predominantly through the Novel Foods Regulation, there is still a wide disparity between the stringency of regulation of microbial products fed to animals and the comparatively relaxed approach to non-novel microbial products intended for human consumption. In the United States, the onus is on self-regulation of the manufacturer, with the Generally Recognised As Safe (GRAS) and Dietary Supplement Health Education Act (DSHEA) notification schemes encouraging industry to be more open about the ingredients they market. In Japan, the Foods for Special Health Use system continues to gain recognition as more products are approved, and is a potential model for other countries in regulating functional foods. Despite the different approaches to regulating these products, safety of microorganisms such as lactic acid bacteria in the food chain is paramount in all countries. This paper discusses the regulatory requirements of microbial products, predominantly lactic acid bacteria within the global markets, focusing mainly on the developments in Europe.     

Phospholipid fatty acid and lipopolysaccharide fatty acid signature lipids in methane-utilizing bacteria

The effect of human bile juice and bile salts (sodium cholate, sodium taurocholate, sodium glycochenodeoxycholate and sodium chenodeoxycholate) on growth, sporulation and enterotoxin production by enterotoxin-positive and enterotoxin-negative strains of Clostridium perfringens was determined. Each bile salt inhibited growth to a different degree. A mixture of bile salts completely inhibited the growth of enterotoxin-positive strains of this organism. Human bile juice completely inhibited the growth of all the strains at a dilution of 1:320. A distinct stimulatory effect of the bile salts on sporulation was observed in the case of C. perfringens strains NCTC 8239 and NCTC 8679. The salts also increased enterotoxin concentrations in the cell extracts of the enterotoxin-positive strains tested. No effect on enterotoxin production was detected when an enterotoxin-negative strain was examined.     

Lactic acid bacteria in the inhibition of Fusarium graminearum and deoxynivalenol detoxification

Aims: Considering the agronomic and industrial damage that is caused by the fungus Fusarium graminearum, as well as the serious health risks it poses to humans and animals exposed to F. graminearum‐produced mycotoxin deoxynivalenol (DON), this study evaluated the ability of different lactic acid bacteria (LAB) strains to inhibit fungal development and remove DON in vitro. Methods and Results: The antagonistic effects of strains and commercial cultures of LAB were evaluated against F. graminearum IAPAR 2218 by the agar diffusion method. Additionally, the influence of the culture media, pH and the presence of lactic and acetic acid on these effects was tested. The capacity to remove DON by viable cells and heat‐inactivated cells was analysed in liquid media and quantified by high performance liquid chromatography (HPLC). All isolated strains and commercial cultures inhibited the fungus and removed DON. The pH and culture media concentration did not influence these abilities, but heat inactivation had a strong effect on the ability of bacteria to remove mycotoxin. Conclusions: The isolated bacteria are able to inhibit F. graminearum growth and remove DON in vitro. Significance and Impact of the Study: This study suggests potential application of the isolated LAB strains in the inhibition of F. graminearum IAPAR 2218 and DON removal in vitro.     

仙客来软腐病拮抗细菌鉴定及其生物防治效果

目的为筛选出仙客来软腐病拮抗细菌及评价其生防效果。方法通过分离和筛选,从温州泽雅高山基地采集健康的仙客来植株分离到13株内生细菌对仙客来软腐病病原菌有较强的抑制作用,其中菌株Y1活性最强且遗传稳定。通过形态特征、生理生化特性分析、16SrDNA序列测定及其系统发育分析研究。结果菌株Y1鉴定为芽胞杆菌,将菌株Y1以发酵液灌根方式回接正常仙客来植株,菌株Y1的发酵液处理仙客来软腐病的防效均大于60％以上。结论菌株Y1具有生防的特点,在花卉产业上具有应用潜力。     

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。     

黄瓜根际重要病原与其拮抗菌消长规律的研究

研究了4个不同黄瓜品种根际两类重要土传植物病原菌(Pythiumspp.和Fusariumoxysporum f.sp.cucumerinum)的种群动态变化.结果表明,同一品种不同生长期间种群数有差异,与通常的发病规律相吻合.统计分析可见,腐霉种群和尖孢镰刀菌黄瓜专化型种群品种间差异极显著(F=495.54>F_0.01=7.59;F=2355.57>F_0.01=7.59).整个生育期,所有黄瓜品种种群数极显著地高于其它时期的腐霉种群数,结主蔓瓜期镰刀菌种群数极显著地高于其它时期的镰刀菌种群数.同时,2种病原菌与其拮抗菌均呈较密切的正相关关系,相关系数分别为0.95和0.81.     

具有拮抗空肠弯曲杆菌能力鸡源乳酸菌的筛选及特性

【目的】从鸡粪中筛选具有拮抗空肠弯曲杆菌能力的乳酸菌,研究其肠道益生特性,探讨其对空肠弯曲杆菌鞭毛毒力因子的影响。【方法】利用牛津杯法测定40株鸡粪源乳酸菌菌株的抑菌活性以确定抑菌性能好的菌株,利用16S r RNA基因分析进行菌株鉴定,采用HT-29细胞测定菌株的细胞粘附能力,通过模拟胃肠液实验分析菌株对胃肠道环境的耐受性,利用扫描电镜分析乳酸菌无细胞提取物对空肠弯曲杆菌鞭毛毒力因子的影响。【结果】从鸡粪中分离得到40株菌株,进一步筛选得到X13、X14和G20等3株拮抗空肠弯曲杆菌能力较强的菌株,经16S r RNA基因序列分析分别鉴定为罗伊氏乳杆菌、唾液乳杆菌和鸡乳杆菌;HT-29细胞粘附实验表明X13、X14及G20的粘附指数分别为11.5、20.3和14.3个/细胞,均具有良好的粘附能力;3株乳酸菌对人工胃肠液均具有良好的耐受性;扫描电镜观察表明,与对照组相比,3株纯培养乳酸菌无细胞提取物均能抑制空肠弯曲杆菌鞭毛毒力因子的合成。【结论】从鸡粪中筛选得到了3株能有效抑制空肠弯曲杆菌生长并能抑制其鞭毛合成的乳酸菌,有望作为拮抗性饲用益生菌用于控制禽畜的空肠弯曲杆菌感染。