Safety assessment of Bifidobacterium longum JDM301 based on complete genome sequences

AIM： To assess the safety of Bifidobacterium/ongum （B. longum） JDM301 based on complete genome sequences. METHODS： The complete genome sequences of JDM301 were determined using the GS 20 system. Putative virulence factors, putative antibiotic resis- tance genes and genes encoding enzymes respon- sible for harmful metabolites were identified by blast with virulence factors database, antibiotic resistance genes database and genes associated with harmful metabolites in previous reports. Minimum inhibitory concentration of 16 common antimicrobial agents was evaluated by E-test RESULTS： JDM301 was shown to contain 36 genes as- sociated with antibiotic resistance, 5 enzymes related to harmful metabolites and 162 nonspecific virulence fac- tors mainly associated with transcriptional regulation, adhesion, sugar and amino acid transport. B. longum JDM301 was intrinsically resistant to ciprofloxacin, ami- kacin, gentamicin and streptomycin and susceptible to vancomycin, amoxicillin, cephalothin, chloramphenicol, erythromycin, ampicillin, cefotaxime, rifampicin, imi- penem and trimethoprim-sulphamethoxazol. JDM301 was moderately resistant to bacitracin, while an earlier study showed that bifidobacteria were susceptible to this antibiotic. A tetracycline resistance gene with the risk of transfer was found in JDM301, which needs to be experimentally validated. CONCLUSION： The safety assessment of JDM301 using information derived from complete bacterial ge- nome will contribute to a wider and deeper insight into the safety of probiotic bacteria.

Effect of Bifidobacterium longum 35624 on disease severity and quality of life in patients with irritable bowel syndrome

BACKGROUND Bifidobacterium longum 35624 has shown efficacy in improving irritable bowel syndrome(IBS)symptoms compared with placebo in double-blind randomized studies.However,few data are available from real-life clinical practice or from studies that used Rome IV criteria to diagnose IBS.AIM To assess the effect of B.longum 35624 on IBS severity and quality of life in a reallife setting.METHODS From November 2018 to January 2020,278 patients with IBS(according to Rome IV criteria)were enrolled in a prospective,open-label,multicenter observational study by private practice gastroenterologists to received one capsule of B.longum 35624(10^(9) colony-forming units)per day for 30 d.Participation in the study was independently proposed to patients during spontaneous consultations.Disease severity(assessed by the IBS severity scoring system)and patient quality of life(assessed by the IBS quality of life questionnaire)were compared between the inclusion visit(baseline)and the visit at the end of 30 d of treatment.The characteristics of patients were described at baseline.Continuous variables comparisons between inclusion and end-of-treatment visits were performed using the t-test and Kruskal-Wallis test.Categorical variables comparisons were performed using theχ^(2) test.RESULTSA total of 233 patients,with a mean age of 51.4 years and composed of 71.2%women,were included in the study.Of these patients,48.1%had moderate IBS and 46.4%had severe IBS.After a 30-d treatment period with one B.longum 35624 capsule per day,a significant decrease in IBS severity was observed compared to baseline(mean±SD,IBS severity scoring system scores:208±104 vs 303±81,P<0.001)and 57%of patients moved to lower severity categories or achieved remission.The quality of life of patients was also improved by the treatment(IBS Quality of Life questionnaire score:68.8±20.9 vs 60.2±20.5;P<0.001)and 63.8%of patients were satisfied with the treatment.CONCLUSION Thirty days of treatment with B.longum 35624 reduces disease severity and improves the quality of life of patients with IBS,particularly those with the most severe forms of IBS.

Impact of Bifidobacterium longum NSP001 on DSS-induced colitis in conventional and humanised mice

Most scientific investigations regarding inflammatory bowel disease(IBD)pathogenesis or therapeutic strategies use dextran sulfate sodium(DSS)-induced models performed on mice.However,differences between human and animal microbiota may confound the data reproducibility from rodent experiments to clinical trials.In this study,the intervention effects of Bifidobacterium longum NSP001 on DSS-induced colitis were investigated using mice colonized with either native or humanised microbiota.Disorders in disease activity index(DAI),morphology and histology of colon tissue,intestinal permeability,and secretion of MPO,TNF-αand IL-6 were ameliorated by daily intake of live B.longum NSP001 cells in both conventional and humanised colitis mice.But the abnormal thymus index,and colonic production of ZO-1 and iNOS were improved only in colitis mice treated with B.longum NSP001 and humanised microbiome.The accumulation of acetic acid and propionic acid in colon microbiome,and the optimization of primary bile acid biosynthesis and glycerophospholipid metabolism pathways in cecum commensals were likely to explain the beneficial effects of B.longum NSP001.These data revealed that intestinal microbiome baseline would possibly affect the manifestation features of interventions by probiotics or dietary components and highlighted the necessity to include humanised microbiome while investigating potential therapeutic strategies based on rodent models.

Bifidobacterium longum CCFM1077 Attenuates Hyperlipidemia by Modulating the Gut Microbiota Composition and Fecal Metabolites:A Randomized,Double-Blind,Placebo-Controlled Clinical Trial

An increasing number of studies have indicated that gut microbiota and its metabolites are crucial in the development of hyperlipidemia.Bifidobacterium longum(B.longum)CCFM1077 has been shown to have lipid-lowering effects in animals.This study aimed to evaluate the potential of B.longum CCFM1077 in lowering the lipid levels in patients with hyperlipidemia and investigate the effect of this bacterium on serum lipid abnormalities,gut microbiota,and fecal metabolites in these patients.This study was a six-week,randomized,double-blind,and placebo-controlled pilot clinical trial.Subjects with hyperlipidemia(N=62)were randomly assigned to receive placebo(N=31)or B.longum CCFM1077(1×1010colony-forming units(CFUs)per day;N=31).Serum lipid levels including total cholesterol(TC),lowdensity lipoprotein cholesterol(LDL-C),total triglyceride(TG),and high-density lipoprotein cholesterol(HDL-C)were examined at the baseline and interventio nal endpoints.Changes in the gut microbiota composition and diversity were measured based on 16S ribosomal RNA(rRNA)sequencing of the V3-V4region at the end of the intervention period.Non-targeted metabolomics of the feces was performed using ultra-performance liquid chromatography(UPLC)-Q-Exactive Orbitrap/mass spectrometer.Oral administration of B.longum CCFM1077 for six weeks significantly decreased the serum levels of TC(p<0.01)and LDL-C(p<0.01)in patients with hyperlipidemia.B.longum CCFM1077 treatment markedly increased gut microbiota diversity and the relative abundance of anti-obesity-related genera,including Lactobacillus,Butyricicoccus,Bifidobacterium,and Blautia,whereas it decreased the relative abundance of obesity-related genera,including Alistipes,Megamonas,and Catenibacterium.Additionally,some key metabolites(bile acids(BAs),biotin,and caffeine)and their corresponding metabolic pathways(primary BA biosynthesis,and taurine and hypotaurine,biotin,purine,and caffeine metabolisms)were enriched by B.longum CCFM1077,and thus it may lower lipid levels.B.longum CCFM1077 is a probiotic strain with the potential to lower serum TC and LDL-C levels patients with hyperlipidemia.The underlying mechanism may be related to the increased abundance of anti-obesity-related genera and fecal metabolites.These findings provide a foundation for future clinical applications of lipid-lowering probiotics in managing individuals with hyperlipidemia.

Safety Evaluations of Long-Term and Excessive Intakes of Bifidobacterium longum CLA8013: A Placebo-Controlled, Randomized, Double-Blind Study

Heat-killed Bifidobacterium longum CLA8013 has been demonstrated to improve the frequency of defecation, straining, and pain during defecation in human placebo-controlled, double-blind, parallel-group studies. We conducted a randomized, double-blind, placebo-controlled, parallel-group study to evaluate the safety of both long-term and excessive intakes of heat-killed B. longum CLA8013, when used as a food with functional claims. In both tests, 30 healthy volunteers were divided into two groups: an active group that ingested heat-killed B. longum CLA8013 and a placebo group. In the long-term intake safety study, participants in the active group ingested 25 billion cells/day for 12 weeks. In the excessive intake safety study, participants in the active group ingested 125 billion cells/day for 4 weeks. Physical, hematological, biochemical, and urine examinations were conducted, and adverse events were evaluated in both studies. The studies revealed no abnormalities in any of the safety tests. In conclusion, no safety-related issues were identified with long-term or excessive intake of heat-killed B. longum CLA8013.

Modulatory effects of Bifidobacterium longum BB536 on defecation in elderly patients receiving enteral feeding

AIM:To investigate the effects of the probiotic Bifidobacterium longum BB536 on the health management of elderly patients receiving enteral feeding.METHODS:Two double-blind,placebo-controlled trials were performed with long-term inpatients receiving enteral tube feeding at Kitakyushu Hospital Group,Fukuoka,Japan.BB536 was administered as BB536-L and BB536-H powders that contained approximately 2.5 × 10 10 and 5 × 10 10 cfu of BB536,respectively.In the first trial,83 patients(age range:67-101 years) were randomized into 2 groups that received placebo(placebo group) or BB536-H(BB536 group) powders.In the second trial,123 patients(age range:65-102years) were randomized into 3 groups,and each group received placebo(placebo group),BB536-L(BB536-L group),or BB536-H(BB536-H group) powders.Each patient received the study medication for 16 wk after 1 wk of pre-observation.Fecal samples were collected from each patient prior to and after the intervention during Trial 2.Clinical observations included body temperature,occurrence of infection,frequency of defecation,and fecal microbiota.RESULTS:No significant changes were observed in the frequency of defecation for either treatment in Trial 1.However,a significant change was noted in the BB536-L group(P = 0.0439) in Trial 2 but not in the placebo or BB536-H groups.Subgroup analyses based on the frequency of defecation for each patient during the pre-observation period for both trials revealed significant increases in bowel movements in patients with a low frequency of defecation and significant decreases in the bowel movements of patients with a high frequency of defecation during the intervention period in the BB536 groups.The combination of Trials 1 and 2 data revealed a modulatory effect of BB536 ingestion on the changes in bowel movements.Significantly increased bowel movements were observed in patients in the low frequency subgroup with significant intergroup differences(P < 0.01).Significantly decreased bowel movements were observed in patients in the high subgroup,but no significant intergroup differences were observed compared with the placebo group.BB536 ingestion increased the prevalence of normally formed stools.BB536 intake also significantly(P < 0.01) increased the cell numbers of bifidobacteria in fecal microbiota,and significant intergroup differences were observed at week 16.No adverse events were reported in any group.CONCLUSION:Our results suggest that BB536 ingestion modulated the intestinal environment and may have improved the health care of elderly patients receiving enteral feeding.

Structure and effect on Bifidobacterium longum of exopolysaccharide produced by Weissella cibaria using cost-effective substrates

Maize straw,an abundant agricultural residue,has potential as an eco-friendly resource.The aim of this study was to investigate the struc-ture and effect on Bifidobacterium longum of exopolysaccharide produced by Weissella cibaria using maize straw as a carbon source.In this work,an exopolysaccharide-producing strain was isolated from vegetable juice,which was identified as W.cibaria.Our results demonstrated that exopolysaccharide produced by W.cibaria is a linear glucan containing anα-1,6 glycosidic bond with a molecular weight of 9462 Da.In addition,scanning electron microscopy of exopolysaccharide from W.cibaria revealed the flake structures.In vitro assays showed that the exopolysaccharide from W.cibaria has the ability to stimulate the proliferation of B.longum strain and its metabolism to produce acetic acid.This work provides a scientific reference for the potential application of maize straw and a new insight into an eco-friendly carbon source to produce exopolysaccharide.

嗜热酸性Ⅲ型普鲁兰水解酶协同压热制备莲子抗性淀粉的工艺优化及其功能特性研究

本研究以莲子淀粉为原料,采用嗜热酸性Ⅲ型普鲁兰水解酶(TK-PUL)与压热联合制备RS3型抗性淀粉(EHP-LRS3)。通过单因素实验和响应面试验对TK-PUL与压热联合制备EHP-LRS3的工艺参数进行了优化,采用扫描电子显微镜和X-射线衍射对EHP-LRS3的形貌、晶体结构进行了观察与分析,并考察了EHP-LRS3对长双歧杆菌的促增殖能力。结果表明,在TK-PUL酶解温度为80℃时制备EHP-LRS3的最佳工艺为:向质量分数为35.32%的莲子淀粉乳(pH5.00)中添加25.00 U/g(莲子淀粉)的TK-PUL,将混合物于80℃处理12.70 h,再将其依次于121℃压热处理10 min、4℃回生处理24 h。在最佳工艺条件下,EHP-LRS3的得率为58.46%。扫描电镜分析显示EHP-LRS3呈不规则的沟壑状结构。X-射线衍射分析表明EHP-LRS3的晶体结构呈现出不同于莲子淀粉A型晶体结构的B型晶体结构。EHP-LRS3对长双歧杆菌的促增殖能力优于压热法制备的RS3型抗性淀粉(HP-LRS3)。本研究采用TK-PUL与压热联合制备得到高得率的RS3型抗性淀粉(EHP-LRS3),并验证了EHP-LRS3对长双歧杆菌的促增殖能力,为莲子淀粉的高值化利用提供了理论依据。

绣球菌多糖营养液发酵培养长型双歧杆菌的研究

为探索绣球菌多糖对长型双歧杆菌增殖生长的影响,以绣球菌多糖替代MRS肉汤培养基中的葡萄糖制备成发酵培养长型双歧杆菌的绣球菌多糖营养液,绣球菌多糖的质量浓度设置为0%~1.8%形成7个浓度梯度,同时选取MRS肉汤培养基和PYG液体培养基作为对照,向上述9组培养基接种少量且等量的长型双歧杆菌,发酵培养0、12、24、36、48、72 h,取样测定活性双歧杆菌生长动态变化,考察双歧杆菌在各组培养基中的增殖趋势。结果表明,绣球菌多糖能被长型双歧杆菌分解利用,活菌浓度与培养基中绣球菌多糖质量浓度存在明显的正相关性,当绣球菌多糖质量浓度为0.3%时,发酵原液的活菌峰值数量即可超过10~6CFU/mL,当绣球菌多糖质量浓度为1.0%时,发酵原液的活菌峰值数量超过10~7CFU/mL,其优势在于能够较长时间维持双歧杆菌接近峰值活菌数量水平,具有减缓双歧杆菌衰亡的作用。此项研究为液体发酵法获得更高的双歧杆菌活性菌体数量及保持液态产品较高的活菌数量提供了新材料和新方法。

人源分离长双歧杆菌长亚种的体外益生特性分析

对新疆伊宁县哈萨克族学龄儿童粪便样品双歧杆菌(Bifidobacterium)进行分离鉴定,重点开展长双歧杆菌长亚种(B.longum subsp.longum)菌株的体外益生特征实验。依据groEL功能基因测序和重复性外源性回文聚合酶链反应指纹分型技术,416株双歧杆菌隶属于B.longum、B.bifidum、B.pseudocatenulatum、B.catenulatum和B.breve。依据优势种B.longum subsp.longum的指纹分型,27种基因型显示了个体间菌株的遗传差异,同时发现同一个体肠道有多菌株共存现象。27株代表菌株的体外实验结果表明,菌株2B3-21、1B23-11、2B33-3和1B68-16的耐酸、耐胆盐能力最优,菌株1B68-16、2B13-5、2B33-3和1B39-2的抑菌能力较强;菌株1B38-1、2B33-3、1B68-16和2B13-28体外抗氧化能力较强,综合所有菌株的抗生素耐药性和利用多种植物源聚糖的能力进行考虑,筛选菌株1B68-16和2B33-3作为潜在的益生菌菌株后续开展体内益生特性研究,本研究可为开发适应特定区域人群的优良益生菌株及产品奠定基础。

不同剂量长双歧杆菌联合西兰花种子水提物对结肠炎的缓解作用

长双歧杆菌CCFM1206分离自健康成人粪便,可将萝卜硫苷转化成萝卜硫素(sulforaphane,SFN),该文研究了西兰花种子水提物(broccoli seed extract,BSE)以及其联合不同剂量的长双歧杆菌CCFM1206(10^(8)、10^(9)和10^(10)CFU)对小鼠肠内SFN水平的调控以及对右旋糖酐硫酸酯钠(dextran sulfate sodium,DSS)诱导结肠炎的缓解作用。研究发现,与BSE组相比,补充10^(9)和10^(10)CFU长双歧杆菌CCFM1206后,小鼠粪便中SFN和N-乙酰萝卜硫素(sulforaphane N-acetyl-L-cysteine,SFN-NAC)总量由30.84μmol/g分别提高至45.48和49.32μmol/g(P<0.05);仅摄入BSE(200 mg/kg小鼠体重),能有效缓解小鼠结肠缩短、降低炎症因子水平(IL-6、IL-1β和TNF-α)、增强抗氧化酶活力(GSH、SOD)、上调紧密连接蛋白的基因转录水平和蛋白表达水平,激活Nrf2信号通路并抑制NF-κB信号通路;补充10^(8)CFU长双歧杆菌CCFM1206效果与BSE无显著差异,而补充10^(9)和10^(10)CFU长双歧杆菌CCFM1206在激活Nrf2和抑制NF-κB信号通路方面更加优异,这可能与产生更多SFN有关。该研究可为开发缓解结肠炎的膳食制剂提供理论依据和剂量参考。

长双歧杆菌CCFM1077缓解小鼠肝内胆汁淤积症的作用机制

肝内胆汁淤积症是一种胆汁分泌及排泄异常引起的病理状态,对人体健康有不利影响。使用α-萘异硫氰酸酯(ANIT)构建肝内胆汁淤积小鼠模型,探究长双歧杆菌CCFM1077(Bifidobacterium longum CCFM1077)对该症状的缓解作用。结果表明,B. longum CCFM1077可显著改善ANIT诱导的小鼠肝脏组织损伤,降低血清中谷草转氨酶(AST)、谷丙转氨酶(ALT)、碱性磷酸酶(ALP)等主要肝功能相关酶水平以及胆汁酸(BAs)浓度。此外,B. longum CCFM1077可能通过激活肠-肝轴FXR-FGF-15信号通路来上调fxr基因的表达,进而抑制BAs合成基因cyp7a1的表达。该菌株可显著提高具有高胆盐水解酶活性的乳杆菌属、双歧杆菌属等肠道共生菌的相对丰度,降低小鼠肝脏中结合态BAs(T-β-MCA、TCDCA、TUDCA)水平,升高游离态BAs(CDCA、CA、DCA、UDCA)水平,进而促进BAs排出体外。B. longum CCFM1077可降低小鼠肠道中志贺氏埃希氏菌属的相对丰度,升高Ruminococcaceae_UCG_014菌属的相对丰度。这些结果表明B. longum CCFM1077能够通过抑制BAs的合成代谢来缓解肝内胆汁淤积,这与菌株调控小鼠肠道菌群结构有关。

长双歧杆菌婴儿亚种利用母乳低聚糖的分子机制及益生作用研究进展

母乳是婴儿早期最主要的营养来源,它可以满足婴儿出生后6个月内的所有营养需求。母乳还含有许多生物活性物质,能够调节肠道菌群,促进免疫系统发育,增强肠道屏障。母乳低聚糖(human milk oligosaccharides,HMOs)是母乳中的活性物质之一,它们无法被婴儿直接消化吸收,但可以作为一种益生元刺激肠道菌群的建立与进化。长双歧杆菌婴儿亚种(Bifidobacterium longum subsp. infantis)是母乳喂养婴儿肠道中的优势微生物,几乎拥有代谢主要HMOs所需的所有基因簇,其与HMOs的互作对早期婴儿肠道健康起着关键作用。本文综述了HMOs的组成和结构,描述了B. longum subsp. infantis对HMOs的利用方式,并总结了B. longum subsp. infantis代谢HMOs对婴儿产生的益生作用,以期为探究HMOs与肠道菌群的互作机制以及该机制对婴儿肠道发育和成熟的作用奠定基础。

长双歧杆菌胞外多糖对非酶糖基化的抑制作用

利用人粪便中分离的一株长双歧杆菌ZJ1株胞外多糖提取物(ZJ1-EPS),分别采用丙酮醛(MGO)诱导牛血清白蛋白(BSA)和人皮肤细胞非酶糖基化(AGEs)模型和葡萄糖诱导斑马鱼AGEs模型,探究ZJ1-EPS抑制AGEs的作用和机制。结果表明,ZJ1-EPS对AGEs生成有明显的抑制作用,同时可显著抑制角质细胞和成纤维细胞中丙酮醛(MGO)诱导的MMP-1表达,促进胶原蛋白的表达。研究揭示了双歧杆菌胞外多糖提取物具有抑制AGEs生成的作用,提示其用于皮肤抗衰的作用机制和应用潜力。

益生菌微囊化抗逆性能研究

以未微囊化的游离益生菌为对照,研究一种新型益生菌微囊化包被在不同胁迫条件下的生长存活情况。从长期储存、高温高湿、酸性环境等方面验证了微囊化包被技术有助于益生菌在恶劣环境下保持活力和增强稳定性。微囊化植物乳植杆菌和长双歧杆菌的常温长期储存存活率比未微囊化对照组分别提高79.02%和70.73%,差异显著(P<0.05)。高温高湿环境下,未微囊化包被的菌粉几乎完全失活。随着高温处理时间的增加,微囊化植物乳植杆菌和长双歧杆菌存活率分别为32.14%和40.36%。在固定湿度65%条件下,随着储存时间的增加,微囊化的植物乳植杆菌仍有14.29%的存活率,长双歧杆菌仍有10.54%的存活率。在模拟胃液中,处理120 min后,微囊化植物乳植杆菌和长双歧杆菌的存活率比菌粉组分别提高了59.22个百分点(P<0.05)和64.24个百分点(P<0.05)。在模拟肠液中,处理120 min后,微囊化植物乳植杆菌和长双歧杆菌的存活率比菌粉组分别提高了34.80个百分点(P<0.05)和33.82个百分点(P<0.05)。因此,微囊化包被技术能提高益生菌在恶劣环境下的存活力,增强抗逆性。

长双歧杆菌BBMN68微胶囊的制备及其应用性评价

长双歧杆菌BBMN68分离自广西巴马长寿老人粪便,已证明其具有双歧杆菌普遍的生理功能。为解决其不耐酸、不耐氧的缺点,本实验采用微胶囊包埋技术,以海藻酸钠、乳清蛋白以及VE为壁材,在氮气体系中采用挤压法包埋该双歧杆菌活菌体制备湿微胶囊和冻干微胶囊。结果表明:海藻酸钠、乳清蛋白和VE质量分数分别为2%、3%和10%条件下制备的湿微胶囊在酸奶中保存21 d仍能保持106 CFU/g以上的活菌数,耐胃酸实验2.0 h时活菌数仍高达3.16×107 CFU/g,肠溶实验中微胶囊在2.0 h实现完全崩解;海藻酸钠和乳清蛋白质量分数为2%和3%,氮气环境下制备的冻干微胶囊通过恒温加速实验测定可在室温条件下贮藏长达75 d。通过微胶囊包埋技术较好地解决了长双歧杆菌BBMN68不耐酸、不耐氧的缺点,同时也提供一种新型有效的补充肠道益生菌的形式。

海藻糖在双歧杆菌冻干菌粉制备和保藏中生物保护作用的初探

对新型保护剂海藻糖在长双歧杆菌 (Bifidobactreriumlongum)冻干菌粉制备和保藏中的生物保护作用进行了初步研究。结果表明 :4种双糖保护剂中 ,海藻糖的细胞冻干存活率分别是蔗糖的 6倍和麦芽的 4 5倍 (P<0 0 1) ,而且显著高于乳糖 (P <0 0 5 ) ;4种复合保护剂中添加海藻糖后 ,细胞冻干存活率均显著提高 (P <0 0 1) ;海藻糖还可明显改善冻干菌粉的细胞贮藏稳定性 。

长双歧杆菌TTF菌株增强机体免疫活性研究

通过长双岐杆菌TTF活菌、菌体破碎物和发酵上清液3种处理物灌胃正常小鼠和免疫功能低下小鼠试验发现,长双歧杆菌TTF的3种受试物对环磷酰胺(Cy)造成的免疫功能低下小鼠模型(IDMM)3项免疫指标均有显著(P<0·05)或极显著(P<0·01)影响,且在本试验选取的3个剂量范围内基本呈量效关系。B·longumTTF的3种受试物对IDMM的非特异性免疫功能的影响普遍大于对小鼠的细胞免疫和体液免疫的影响;对正常小鼠免疫功能影响的水平低于其对IDMM各项免疫指标的影响,且无论活菌、菌体破碎物、发酵上清液均不会改变小鼠自身正常的免疫功能。急性毒性试验表明,B·longumTTF3种处理物对健康小鼠无急性毒性。就3种处理物来讲,发酵上清液组的效果高于菌体破碎物和活菌。

泡菜乳酸菌筛选鉴别及耐受性和促益生菌增殖的研究

以寻求提高我国传统发酵型腌渍蔬菜益生作用的有效途径为目的,采用平板划线分离的方法从典型泡菜产品中分离筛选乳酸菌,考察其在模拟人体胃肠环境条件下的耐受能力,选择耐受力强的菌株进行双歧杆菌增殖试验和菌株分类鉴别。结果显示:2株乳酸菌在pH为2.5-4.5的模拟胃液环境中停留2h活菌数仍达106CFU/mL以上,在0.3%的模拟肠道胆汁环境停留4h活菌数仍保持在初始状态;发酵时间6h内乳酸菌株对长双歧杆菌生长有促进作用。经形态特征观察、气相色谱检测代谢有机酸种类和热变性温度法测定DNA中G+C(鸟嘌呤+胞嘧啶)含量,确认筛选出的优质菌株为同型发酵乳杆菌属。

真空冷冻干燥与喷雾干燥长双歧杆菌的工艺比较研究

为有效延长双歧杆菌的保存期和耐受性,利用真空冷冻干燥及喷雾干燥法制备活性菌粉。研究两种干燥方法的工艺参数,并对干燥得到的活性菌粉性能进行比较。真空冷冻干燥法制备的长双歧杆菌活性菌粉的活菌数为7.98×109CFU/g、存活率90.9%、含水量3.8%,4℃保藏90d后活菌数为2.5×108CFU/g,菌粉的水溶性好;喷雾干燥法制备的活性菌粉的活菌数为4.4×109CFU/g、存活率82.2%、包埋率71.9%、含水量5.6%,4℃保藏90d后活菌数为4×108CFU/g,菌粉在水中的溶解时间较长。真空冷冻干燥成本较高、操作时间长、菌粉的保藏期较短;而喷雾干燥工艺简单、生产成本低、工作效率高,包埋的菌粉保藏期较长。