Dominant Lactic Acid Bacteria and Their Antimicrobial Profile from Three Fermented Milk Products from Northern Namibia

The present study focused on the isolation, identification and antimicrobial profile of the dominant lactic acid bacteria from three traditional fermented milk products namely: Omashikwa, Mabisi and Mashini Ghamushikwa from the north-central and north-eastern parts of Namibia. The microbiological and antimicrobial activities of these products fluctuate from one region to another depending on the local indigenous microflora. Omashikwa and Mashini Ghamushikwa fermentation processes involves the addition of Boscia albitrunca root (Omunkuzi) and butter churning. The root contributes to the flavor of the product, increasing the milk fermentation rate and churning. Mabisi is produced by letting the milk to ferment naturally until the water is separated from the whey. The water is then decanted, and the whey is shaken until it is smooth without removal of fat. A total of 180 isolates of Lactic acid bacteria (LAB) were obtained and identified based on their phenotypical characterization. Cell free supernatants (CFS) of the 180 LAB isolates were evaluated for antimicrobial activities against selected food borne pathogens;Escherichia coli ATCC 25,922, Staphylococcus aureus ATCC 25,923, Bacillus cereus ATTC 10,876, Candida famata and Geotrichum klebahnii using the well diffusion assay. Twenty LAB isolates having the highest inhibitory effects were selected for biochemical identification using API 50 kit and these were identified as being;Lactobacillus plantarum (53%), Lactobacillus rhamnosus (29%), Pediococcus pentosaceus (6%), Lactobacillus paracasei ssp. paracasei (6%) and Lactococcus lactic ssp. lactis (6%). Pediococcus pentosaceus showed the highest inhibitory effect on all the indicator strains. This study provides an insight into LAB diversity of unstudied Namibian fermented milk products and reports a potential production of antimicrobial compounds which is significant in the standardization of protective starter cultures which can be used to control fermentation process and shelf life extension of dairy products in Namibia.

Isolation, Characterisation and Evaluation of Antiulcerogenic Potentials of Probiotic Lactic Acid Bacteria Isolated from Fermented Milk and Palm Wine against Ethanol-Induced Gastric Ulcer in Mice

Background: Gastric ulcer is one of the most common gastrointestinal diseases with a worldwide prevalence of about 40% in the developed countries and 80% in Africa. Acid inhibitors, anticholinergics, histamine H2-antagonists and antibiotics are commonly used to treat gastric ulcer. However, the accumulating evidence for resistance to antibiotics and the side effects of antibiotics and acid inhibitors, anticholinergics and histamine H2-antagonists. Therefore, there is an urgent need for approaches to treat and prevent gastric ulcer. One alternative strategy is the use of probiotic lactic acid bacteria. Aim of the study: This study aimed to isolate and characterised probiotic lactic acid bacteria from palm wine and fermented milk, and to evaluate their antiulcerogenic potentials on ethanol-induced gastric ulcer in mice. Methods: Probiotic lactic acid bacteria were isolated from the fermented milk and palm wine using pour plate technique on MRS agar and identified using the 16S r RNA gene sequencing. For functional properties and selection, acid and bile salt tolerance were evaluated based on viable colony count on MRS agar. Two probiotic lactic acid bacteria were selected for in vivo studies. Fifty-four healthy young adult Balb/c mice were randomly divided into 9 groups of 6 mice each. Gastric ulcer was induced in mice using one oral dose of absolute ethanol (10 mL/kg body weight). The probiotic lactic acid bacteria (F1 and F2) at different doses (MF3 = 9 × 108 CFU/mL, MF6 = 1.8 × 109 CFU/mL and MF9 = 2.7 × 109 CFU/mL) and omeprazole (20 mg/kg) (a reference drug) were orally administrated daily for 14 days before ulcer induction. These mice were sacrificed 1hour after induction and the stomach contents were collected for volume and pH determination. The stomachs were subjected to macroscopic, biochemical and histopathological analysis. Results: Among the isolates obtained, two were considered to have the best acid and bile tolerance capacity (viable count > 7.5 logCFU/ml) and were identified as Limosilactobacillus fermentum strain BB101 (F1) and Lactobacillus casei strain 02 (F2). Oral administration of probiotics Lactic acid bacteria F1 and F2 significantly attenuated gastric ulcer as revealed by significant reduction (P Conclusion: The results of this study revealed that palm wine and fermented milk are sources of potential probiotic lactic acid bacteria, that is lactobacillus fermentum strain BB101 and Lactobacillus casei 02 with excellent bile and acid tolerance capacity. Also, these probiotic lactic acid bacteria exhibit gastroprotective effect on ethanol-induced gastric ulcer via antioxidant, enhance gastric ulcer healing, antacids, and anti-secretary effects.

Characterization of Antibacterial Activity and Potential as Probiotic of Lactic Acid Bacteria Isolated from Goat＇s Milk in Algeria

Lactic acid bacteria （LAB） were isolated from goat＇s milk in different north west region of Algeria. A total of 233 isolates were identified as LAB. However, only 11 strains showed excellent inhibition zones on agar when Salmonella lyphimorium ATCC 13311 was used as an indicator for preliminary detection of antagonistic activity. After elimination of inhibition due to acid and H202, Staphylococcus aureus ATCC 25923 was used for secondary screening for antagonistic activity of these 11 strains. It was found that only 9 strains exhibited a good inhibition zones on agar, and all of them could inhibit E. coli ATCC 25921 and Pseudomonas aeruginosa ATCC 27853 as the third and the forth indicators respectively. Lactococcus lactis subsp, cremoris, Lactobacillus casei subsp, casei, Lactobacillus casei subsp, rhamnosus, Streptococcus salivarius subsp, thermophilus and Lactococcus lactis biovar. diacetylactis were the strains that have a good antibacterial activity, survive in the gastrointestinal conditions and were sensible to the majority of the antibiotics. All isolated strains tolerate pH = 2 and high bile salt concentration.

The Role of Lactic Acid Bacteria in Milk Fermentation

Species of lactic acid bacteria (LAB) represent as potential microorganisms and have been widely applied in food fermentation worldwide. Milk fermentation process has been relied on the activity of LAB, where transformation of milk to good quality of fermented milk products made possible. The presence of LAB in milk fermentation can be either as spontaneous or inoculated starter cultures. Both of them are promising cultures to be explored in fermented milk manufacture. LAB have a role in milk fermentation to produce acid which is important as preservative agents and generating flavour of the products. They also produce exopolysaccharides which are essential as texture formation. Considering the existing reports on several health-promoting properties as well as their generally recognized as safe (GRAS) status of LAB, they can be widely used in the developing of new fermented milk products.

Selection of Lactic Acid Bacteria Isolated from San Simón da Costa Cheese (PDO) in Order to Develop an Autochthonous Starter Culture

Traditional cheeses are an important reservoir of microbial diversity that can have important biotechnological applications, especially with a view to improving the characteristics unique to each type of cheese, and in this respect, starter cultures consisting of autochthonous lactic acid bacteria strains are of particular interest. In the present study, we investigated lactic acid bacteria population diversity in San Simón da Costa cheese (PDO, Galicia, Spain) and found a predominance of the genus Lactobacillus, which by the end of ripening accounted for 78% of the strains isolated in Rogosa agar, around 40% of those in M17 agar and about 10% of those in MSE agar. The main species of lactic acid bacteria identified were Lactococcus lactis subsp. lactis, Lactobacillus casei subsp. casei, Lb. paracasei subsp. paracasei, Leuconostoc mesenteroides and Enterococcus faecalis. Virtually all the strains studied from a technological point of view yielded more than or equal to 0.24 g 100 mL-1 lactic acid. Lactococcus lactis subsp. lactis (SS 194), Lactobacillus paracasei (SS 1695 and SS 1689) and Enterococcus faecalis (SS 1378 and SS 1449) strains exhibited the greatest proteolytic capacity. Based on the overall technological aptitude of the tested strains, we can propose starter cultures and co-cultures that include different combinations of previous strains with a view to manufacturing San Simón da Costa cheese from pasteurised milk.

Fermented Goat Milk and Cow Milk Produced by Different Starters of Lactic Acid Bacteria： Quality Studies

Lactic acid bacteria （LAB） is widely used as culture starters in dairy fermentation. The aim of this study was to investigate the quality of fermented goat milk and cow milk, as well as the viability of LAB in the same products. Fermentations were performed with pasteurized goat milk or cow milk added with skim milk （18% of solids） using three separately different starters; yoghurt starter （a combination of Streptococcus thermophilus FNCC-0040 and Lactobacillus bulgaricus FNCC-0041）, single starter of Lactobacillus acidophilus FNCC-0029 and Lactobacillus casei FNCC-0051. The parameters observed were pH, acidity, nutritional quality including protein, fat and lactose content and product＇s viscosity. Acidity, pH and viability of LAB were also monitored during storage at refrigerated temperature （4 ℃） for 28 days. Results show that the different LAB starters did not affect the pH, acidity, lactose and protein content. Differences on LAB starters affected fat content and viscosity. The highest score of viscosity （30.00 Pa.s ± 7.02 Pa.s） was observed on products fermented by yoghurt starters, followed by products obtained using starter of L. acidophilus （17.7 ±11.4） and L. casei （8.62 ±0.35）. Protein content, acidity, pH and viscosity were not significantly different between products obtained from goat milk and cow milk. Fat content in fermented goat milk was higher （5.03% ±0.62%） than in fermented cow milk （3.52% ±0.37%）, however, lactose content was higher in fermented cow milk （5.16% ±0.40%） than in fermented goat milk （4.53% ±0.35%）. Total LAB concentration in fermented cow milk during storage was 8.03± 0.52 logt0 cfu/mL, while in fermented goat milk was 7.81 loglo cfu/mL ± 0.67 loglo cfu/mL. There was a 10.83% decrease in LAB viability in fermented cow milk and 11.40% in fermented goat milk after 28 days of storage. In conclusion, quality of fermented milk is affected by the starters applied, raw milk source and storage period.

Preservation of Raw Camel Milk by Lactoperoxidase System Using Hydrogen Peroxide Producing Lactic Acid Bacteria

This study was conducted to investigate the effect of lactic acid bacteria (LAB) activated lactoperoxidase system (LPs) on keeping quality of raw camel milk at room temperature. Camel milk samples were collected from Errer valley, Babile district of eastern Ethiopia. The level of hydrogen peroxide (H2O2) for activation of LPs was optimized using different levels of exogenous H2O2. Strains of LAB (Lactococcus lactis 22333, Weissella confusa 22308, W. confusa 22282, W. confusa 22296, S. Infatarius 22279 and S. lutetiensis 22319) with H2O2 producing properties were evaluated, and W. confusa 22282 was selected as the best strain to produce H2O2. Storage stability of the milk samples was evaluated through the acidification curves, titratable acidity (TA), total bacterial count (TBC) and coliform counts (CC) at storage times of 0, 6, 12, 18, 24 and 48 hours. The LP activity and the inhibitory effect of activated LPs were evaluated by growing E. coli in pasteurized and boiled camel milk samples as contaminating agent. Results indicated that the W. confusa 22282 activated LPs generally showed significantly (P < 0.05) slower rates of acidification, lactic acid production and lower TBC and CC during the storage time compared to the non-activated sample. The H2O2 producing LAB and exogenous H2O2 activated LPs in pasteurized camel milk significantly reduced the growth of E. coli population compared to non-activated pasteurized milk. Overall, the result of acid production and microbial analysis indicated that the activation of LPs by H2O2 producing LAB (i.e. W. confusa 22282) maintained the storage stability of raw camel milk. Therefore, it can be concluded that the activation of LPs by biological method using H2O2 producing LAB can substitute the chemical activation method of LPs in camel milk.

原驼乳中乳酸菌的分离筛选及特性分析

【目的】挖掘和获得原驼乳中的乳酸菌资源。【方法】采集新疆乌鲁木齐县近效南山周边原驼乳样品,采用平板稀释法分离菌株,观察比对16S rRNA基因序列测序和菌株形态学特性,分析菌株分类学地位,并检测菌株溶血性和有害代谢物质等食用安全性。【结果】获得29株乳酸菌,经鉴定其归属于Leuconostoc、Lentilactobacillus两个属的4个种;菌株均可耐受0.5%胆盐,5%NaCl,且具有较好耐高温、牛奶胨化、抗氧化和抑制细菌等特性;所有菌株均无溶血现象,不产生硝基还原酶;除T12外,均利用氨基酸不产生物胺。【结论】从原驼乳中获得的乳酸菌具有良好的发酵特性和食品安全性。

母乳中乳酸菌多样性及益生菌开发利用研究进展

母乳源益生菌具有安全、适应人体环境等开发利用优势。母乳中乳酸菌的分离、筛选和开发利用成为乳品和乳酸菌产业的研究热点,国内外学者开展了大量关于母乳中乳酸菌的分离鉴定和益生菌的筛选及功能评价工作。深入挖掘母乳中的乳酸菌益生特性及其在产业化应用方面的潜力,将推动我国乳酸菌产业向着高质量发展的方向迈进。作者对母乳中乳酸菌的多样性和益生菌的筛选及开发利用进行了综述,旨在为母乳中乳酸菌的研究和应用提供新的视角和见解。

发酵豆乳乳酸菌的筛选及其对豆乳抗氧化性能的改善作用

该文通过分离纯化、形态观察和16S rDNA鉴定的方法,从传统发酵食品及健康人肠道中筛选出74株乳酸菌。以胃肠液耐受性、产酸能力和增殖能力为指标,初步筛选出5株性能优良的乳酸菌,并将其应用于发酵大豆乳、花生乳和鹰嘴豆乳,进一步测定菌株在3种豆乳中的产酸和增殖能力,筛选出适用于发酵不同豆乳的乳酸菌。其中发酵24 h时,Lactobacillus fermentum LF3.2在三种豆乳中均具有最强的产酸能力,发酵大豆乳和花生乳的pH值达到4.5以下。此时三种发酵豆乳中的活菌数都达到了8 log CFU/mL以上,在大豆乳和花生乳中L.fermentum LF3.2和L.plantarum G1.3增殖能力最强,在鹰嘴豆乳中L.fermentum LF3.2和L.plantarum G1.4的增殖能力最强。三种豆乳经L.fermentum LF3.2、L.plantarum G1.3发酵24 h后其抗氧化活性均显著提高,发酵大豆乳对DPPH·和OH·的清除率比未发酵分别高出23.34%、23.64%,增长量最高。L.fermentum LF3.2更能增加三种豆乳对DPPH·的清除率,而L.plantarum G1.3更能增加三种豆乳对OH·的清除率。本文研究结果对开发功能性发酵豆乳具有一定的指导意义,为乳酸菌应用于植物基发酵食品奠定了理论基础。

内蒙古阿拉善驼乳制品中乳酸菌分离鉴定及微生物多样性研究

内蒙古传统乳制品是乳酸菌的优质培养基,为保藏内蒙古阿拉善地区驼乳制品中的乳酸菌资源,并研究其中微生物多样性,本研究分别采用纯培养方法与宏基因组测序技术进行分析。宏基因组分析表明:阿拉善地区鲜驼乳微生物多样性明显高于酸驼乳,18份样品中共鉴定到157个种。鲜驼乳的优势菌种为乳酸乳球菌(13.22%)和桂林不动杆菌(10.65%);酸驼乳的优势菌种为瑞士乳杆菌(72.66%)、马乳酒样乳杆菌(8.32%)和乳酸乳球菌(4.28%)。纯培养进一步从鲜驼乳和酸驼乳中分离到121株乳酸菌,鉴定为4个属的14个种,其中鲜驼乳的优势菌株为乳酸乳球菌(62.00%),酸驼乳的优势菌株为瑞士乳杆菌(40.00%)、马乳酒样乳杆菌(19.00%),与宏基因组测序结果一致。宏基因组测序联合纯培养法可有效实现驼乳样品微生物多样性分析与乳酸菌资源挖掘,为驼乳的工业化生产与乳酸菌资源利用提供理论依据。

新型稀奶油-大豆分离蛋白香基的制备

为了丰富奶味香基蛋白源营养种类、降低成本并增强其风味强度,选用大豆分离蛋白部分替代稀奶油构建复合体系,采用两种不同的酶法结合乳酸菌发酵法,开发新型奶味香基,同时对两款香基的感官特性、主要代谢物和风味物质进行分析。结果表明,一步酶法结合发酵制备的香基具有较高水平的游离脂肪酸和中长链挥发性酸,并因此呈现出刺激性的酸败味等不良风味;而两步酶法结合发酵制备的香基积累了更高含量的多肽和氨基酸,短链挥发性酸以及3-羟基-2-丁酮、苯甲醛、糠醛、δ-十二内酯等重要挥发性风味物质,并获得更高的感官评价分数,更适于制备新型稀奶油-大豆分离蛋白复合风味香基。

新疆维吾尔自治区呼图壁县驼乳源乳酸菌分离鉴定及其对金黄色葡萄球菌的抑制作用

[目的]分离、鉴定新疆维吾尔自治区呼图壁县驼乳源乳酸菌,评价其对金黄色葡萄球菌的抑制作用。[方法]从呼图壁县某驼场采集健康驼乳样本45份,使用MRS培养基分离乳酸菌,采用细菌16S rDNA序列PCR扩增及测序方法进行分子生物学鉴定。利用点种法、琼脂斑点法和牛津杯双层琼脂扩散法筛选对金黄色葡萄球菌ATCC 29213具有抑制作用的乳酸菌。将MRS培养基的pH值调节至1~10,测定乳酸菌的耐酸能力;在MRS培养基中添加0~0.30%的牛胆盐,测定乳酸菌的耐胆盐能力。应用微量肉汤倍比稀释法测定乳酸菌无细胞上清液(cell-free culture supernatant,CFCS)对金黄色葡萄球菌ATCC 29213的最低抑菌浓度(minimum inhibitory concentration,MIC)和亚抑菌浓度(subinhibitory concentration,SIC);考查CFCS在不同pH值条件下及经酶处理后对金黄色葡萄球菌ATCC 29213的抑制作用变化,初步分析CFCS的抑菌活性物质;利用牛津杯双层琼脂扩散法测定CFCS对驼乳源和奶牛乳房炎源金黄色葡萄球菌野生株的抑制作用。[结果]从45份驼乳中分离得到5种20株乳酸菌,分别为粪肠球菌(Enterococcus faecalis,n=13)、鼠李糖乳杆菌(Lacticaseibcillus rhamnsus,n=1)、发酵黏液乳杆菌(Limosilactobacillus fermentum,n=3)、副干酪乳杆菌(Lactobacillus paracasei,n=1)和融合魏斯氏菌(Weissella confusa,n=2)。经3种方法筛选,鼠李糖乳杆菌KC4株对金黄色葡萄球菌ATCC 29213的抑菌作用最强,且具有良好的耐酸和耐胆盐特性,在pH值为4~7和牛胆盐浓度为0~0.20%的条件下均可正常生长。KC4株的CFCS对金黄色葡萄球菌ATCC 29213的MIC和SIC分别为62.5 mg/mL和7.8125 mg/mL;在pH值为2~5时仍具有抑菌效果,经过胃蛋白酶、过氧化物酶、胰蛋白酶、肽酶、蛋白酶K、过氧化氢酶和木瓜蛋白酶处理后抑菌效果极显著(P<0.01)降低;对驼源和牛源金黄色葡萄球菌野生株均具有良好的抑菌效果。[结论]在呼图壁县驼乳中筛选出1株对金黄色葡萄球菌标准菌株以及驼源和牛源金黄色葡萄球菌野生菌株均具有较强抑制作用的鼠李糖乳杆菌,具有较强的耐酸和耐胆盐能力,其抑菌活性物质可能包括酸、过氧化物和蛋白类物质等。研究结果为驼乳源乳酸菌的开发利用提供了潜在菌种资源。

奶嚼口中乳酸菌的筛选及生物学特性研究

奶嚼口又名朱和、乌日莫,是内蒙古当地特色美食,其乳酸菌含量丰富,有益消化和调节肠道菌群。从奶嚼口中分离纯化了4株乳酸菌,并从形态、生理生化、产酸能力、耐盐、耐酸、耐胆盐等方面进行生物学特性的综合评价。结果表明,4株菌都是植物乳杆菌;4株菌的最适生长温度均为37℃,14 h后均进入稳定期;4株菌的耐盐、耐酸、耐胆盐性均较好。

发酵乳和乳饮料中乳酸菌活菌数ATP检测方法的开发与应用

乳酸菌活菌数作为发酵乳和乳酸菌饮料的产品质量属性,同时作为国家风险抽检项目,目前的检测方法存在操作烦琐、检测周期长、结果滞后等缺点,无法满足企业产品卖点宣称及质量控制,故针对发酵乳和乳饮料中乳酸菌活菌数的快速检测方法进行开发、研究,旨在提高检测结果准确性、稳定性及缩短检测周期。每种微生物中的腺嘌呤核苷三磷酸(Adenosine Triphosphate,ATP)含量都是基本恒定的,而ATP的相对发光单位(Relative Luminescence Unit,RLU)与ATP含量呈线性关系,通过建立产品中乳酸菌数量与ATP的RLU(相对发光单位)的相关关系开发乳酸菌快速检测方法。通过试验证实该方法与国家标准检测方法具有一致性,能够快速、准确地检测产品中乳酸菌数活菌数,为生产销售流通中的质量监测提供一种快捷方便的方法。

乳酸菌发酵乳蛋白水解物对RAW264.7细胞氧化损伤的保护作用

利用乳酸菌发酵乳蛋白水解物(milk protein hydrolysates,MPH)有助于提高乳酸菌水解蛋白的能力,促进功能成分的产生与挖掘。基于不同乳酸菌发酵MPH上清液的体外自由基清除能力和铁离子还原力综合评价,筛选获得一株抗氧化活性较强的鼠李糖乳酪杆菌(Lacticaseibacillus rhamnosus)ST(LST)。LST发酵MPH所得上清液产物(FPS)中,游离氨基酸总量比MPH提高了66.98%,分子质量低于180 Da组分增加8.66%。在H_(2)O_(2)诱导的RAW 264.7细胞氧化损伤模型中,FPS能显著提高细胞存活率,上调核因子E2相关因子2(nuclear factor E2-related factor 2,Nrf2)、超氧化物歧化酶1(superoxide dismutase 1,SOD1)、血红素加氧酶-1(heme oxygenase-1,HO-1)和谷胱甘肽过氧化酶1(glutathione peroxidase 1,GPX1)等抗氧化基因的转录水平。由此表明,鼠李糖乳酪杆菌LST发酵MPH可以有效缓解细胞氧化损伤,具有进一步应用于抗氧化食品开发的潜力。

山羊原奶中可培养乳酸菌多样性及菌株的体外益生特性分析

本研究旨在了解新疆地区山羊原奶中乳酸菌的益生特性、加工特性和安全性,以期为开发功能性乳品奠定一定的基础。实验采用16S rRNA基因测序结合Rep-PCR指纹分型技术对分离出的乳酸菌菌株进行遗传差异分析,检测它们对酸和胆盐的耐受性并对耐受性较好的菌株进行模拟胃肠液耐受性、细胞表面特性(疏水性和自凝聚)、抗菌活性、工艺逆境耐受性(溶菌酶、热)及药敏试验,来评价菌株的体外益生特性和安全性,通过主成分分析筛选最优的益生菌株。研究从15份山羊乳样品中共分离得到23株乳酸菌,包括Leuconostoc mesenteroides(9株)、Lactiplantibacillus plantarum(6株)、Latilactobacillus curvatus(4株)、Enterococcus faecium(2株)、Enterococcus durans(2株)。基于对酸和胆盐耐受性进行初筛的结果表明,有7株菌具有较好的耐受性。其中,2株植物乳植物杆菌(L. plantarum SY43-10和L. plantarum SY43-4)的模拟胃液和肠液处理后活菌数均高于5 lg CFU/mL;24 h自凝集率大于27%、并具有良好疏水性;热和溶菌酶处理后的活菌数仍大于7 lg CFU/mL;药敏试验显示2株菌对氨苄西林和氯霉素表现敏感,对头孢西丁、红霉素和青霉素表现中度敏感或敏感。因此,菌株SY43-10和SY43-4可作为优良的益生菌株,通过体内实验进一步应用于发酵乳品和功能性产品。

基于实时荧光定量环介导等温扩增技术快速检测发酵乳中嗜热链球菌和保加利亚乳杆菌

基于实时荧光定量环介导等温扩增(quantitative loop-mediated isothermal amplification,qLAMP)技术建立发酵乳中嗜热链球菌和保加利亚乳杆菌活菌数快速定量方法。通过优化嗜热链球菌和保加利亚乳杆菌叠氮溴化丙锭(propidium monoazide,PMA)处理条件,对菌浓度对数与相应的循环阈值进行线性拟合,构建标准曲线,建立PMA-qLAMP检测方法。结果表明,该方法对嗜热链球菌的最低定量限为7.2×10^(3) CFU/g,对保加利亚乳杆菌的最低定量限为5.6×10^(4) CFU/g,将该方法应用于市售发酵乳产品活菌数定量检测,显示出良好的灵敏度和实用性。

Bioactivities and ACE-inhibitory peptides releasing potential of lactic acid bacteria in fermented soy milk

This study was designed to evaluate the bioactivities such asβ-glucosidase activity,α-galactosidase activity,and the growth behavior of the Lactobacillus cultures in soy milk medium.Ten Lactobacillus cultures were considered in this study.L.fermentum(M2)and L.casei(NK9)were selected due to their betterα-galactosidase,β-glucosidase activity and growth behavior in soy milk medium during fermentation.Further,soy milk fermented with M2 showed higher proteolytic activity(0.67 OD)and ACE-inhibitory(48.44%)than NK9(proteolytic activity:0.48 OD and ACE-inhibitory activity:41.33%).Bioactive peptides produced during the fermentation of soy milk using the selected Lactobacillus cultures were also identified with potent ACE-inhibitory activity by MALDI-TOF spectrometry,and the identified ACE inhibitory peptide sequences from fermented soy milk were characterized using Biopep database.

复配乳酸菌黑米发酵乳工艺优化及抗氧化活性研究

利用植物乳杆菌、嗜酸乳杆菌和鼠李糖乳杆菌混菌发酵制备黑米发酵乳,通过响应面试验优化发酵工艺,并测定其抗氧化活性。结果表明:当发酵时间4 h、发酵温度37℃、黑米浆与牛奶的体积比1∶1.7时,黑米发酵乳的感官评分达到86.91±3.24,具有较强的抗氧化活性。