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.

Comparative studies of versatile extracellular proteolytic activities of lactic acid bacteria and their potential for extracellular amino acid productions as feed supplements

Background:Increasing understanding on the functions of amino acids (AA) has led to new commercial applications and expansion of the worldwide markets.However,the current technologies rely heavily on non-food grade microorganism and chemical synthesis for the production of AA.Several studies reported that lactic acid bacteria (LAB) have the capability of producing AA owing to their well-established proteolytic system and amino acid biosynthesis genes.Hence,the objectives of this study were to explore the extracellular proteolytic activity of LAB isolated from various Malaysian fermented foods and their potential to produce AA extracellularly as feed supplements.Results:All the studied LAB isolates were versatile extracellular protease producers,whereby extracellular protease activities were detected from acidic to alkaline pH (pH 5,pH 6.5,pH 8) using qualitative and quantitative proteolytic assays.The highest proteolytic activity at pH 5 (15.76 U/mg) and pH 8 (19.42 U/mg) was achieved by Lactobacillus plantarum RG14,while Lactobacillus plantarum RS5 exhibited the highest proteolytic activity of 17.22 U/mg at pH 6.5.As for the results of AA production conducted in de Man,Rogosa and Sharpe medium and analysed by high pressure liquid chromatography system,all LAB isolates were capable of producing an array of AA.Generally,Pediococcus sp.showed greater ability for AA production as compared to Lactobacillus sp.Moreover,the studied LAB were able to produce a few major feed supplement AA such as methionine,lysine,threonine and tryptophan.P.pentosaceus TL-3 recorded the highest methionine and threonine productivity of 3.72 mg/L/h and 5.58 mg/L/h respectively.However,L.plantarum I-UL4 demonstrated a lysine productivity of 1.24 mg/L/h,while P.acidilactici TP-6 achieved up to 1.73 mg/L/h of tryptophan productivity.Conclusion:All the 17 studied LAB isolates possessed versatile extracellular proteolytic system and have vast capability of producing various amino acids including a few major feed supplement AA such as methionine,lysine,threonine and tryptophan.Despite AA production was strain dependent,the studied LAB isolates possessed vast potential and can be exploited further as a bio-agent or an alternative amino acids and bioactive peptide producers.

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.

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.

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.

乳酸菌发酵对雪菊体外活性的影响研究

目的:为对比研究乳酸菌发酵前、后雪菊水提取物体外抗氧化活性、XOD抑制活性、抑菌活性的变化情况。方法:运用紫外-可见分光光度法测定发酵前、后水提物清除DPPH·和ABTS+能力、抑制黄嘌呤氧化酶能力;к-B法检测发酵前、后水提物对大肠杆菌和金黄色葡萄球菌的抑菌能力。对比研究乳酸菌发酵对雪菊水提物体外活性的影响。结果:乳酸菌发酵后雪菊水提物在0.15mg/ml DPPH·和ABTS+清除率较发酵前有明显增加。发酵前、后0.5mg/mL雪菊水提物对XOD抑制率分别为43.16%,62.19%。发酵前、后雪菊水提物对大肠杆菌的抑制性均强于金黄色葡萄球菌。相同浓度下,发酵后抑菌效果高于发酵前。结论:对乳酸菌发酵前、后雪菊水提物体外活性对比研究显示,经乳酸菌发酵后其体外抗氧化活性、抑制XOD活性、抑菌活性均增强,这为初步筛选治疗痛风的药物奠定理论基础。

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。

乳酸菌固态发酵过程中麦麸组分的动态变化

麦麸是小麦加工的主要副产物,营养丰富且产量大,采用乳酸菌处理麦麸可提高其附加值。为明确乳酸菌发酵对麦麸各组分的影响,作者采用植物乳杆菌、鼠李糖乳杆菌、戊糖片球菌和布氏乳杆菌分别对麦麸进行固态发酵,在48 h内每隔8 h取样,分析可溶性膳食纤维、粗蛋白质、淀粉、总酚、植酸等成分的质量分数及DPPH自由基清除能力的动态变化。结果表明,在麦麸基质中,4株乳酸菌在24 h内生长较为迅速;麦麸经乳酸菌发酵后可溶性膳食纤维质量分数显著提高,其中布氏乳杆菌发酵48 h后可溶性膳食纤维质量分数由4.72%增加至6.58%;随着发酵时间的增加,麦麸中淀粉质量分数逐渐降低,粗蛋白质量分数先增加后降低最后趋于稳定;植物乳杆菌在提高麦麸多酚质量分数方面有更好的效果,多酚质量分数由1.34 mg/g增加至3.86 mg/g,麦麸抗氧化活性显著增加;此外,乳酸菌发酵麦麸可显著降低其植酸质量分数。综合而言,植物乳杆菌和布氏乳杆菌在提高麦麸的营养特性方面具有较好的效果,可有效改善麦麸的综合利用价值。

基于文献计量学可视化分析发酵乳风味研究现状

通过文献计量学方法,该研究对Web of Science核心合集及中国知网数据库中2003—2023年间发表的发酵乳风味研究文献进行了可视化分析。分析结果表明,中国(247次)、巴西(131次)、土耳其和美国(各120次)为该研究领域的主要国家。国际上埃及知识库(Egyptian Knowledge Bank,EKB)和内蒙古农业大学是目前该领域中最为重要和关键的机构,各机构合作较为紧密。国内内蒙古农业大学乳品生物技术与工程教育部重点实验室、江南大学食品学院、石家庄君乐宝乳业有限公司和云南农业大学食品科学技术学院是研究发酵乳风味领域研究的核心力量,但合作相对较少。研究热点主要聚焦于“乳酸菌”“风味物质”“发酵乳加工工艺”“风味评价”“品质与应用”等方面,未来还需加强跨机构及跨学科的合作,运用创新技术,以期开发出风味更佳且安全的发酵乳优质产品。

乳酸菌与酵母菌混合发酵羊奶酒的理化特性、抗氧化活性及香气分析

本研究以纯山羊奶为原料,利用六株乳酸菌分别与酿酒酵母混合发酵纯山羊奶制备羊奶酒,以酿酒酵母单一发酵的羊奶酒为对照,分析羊奶发酵过程中的理化特性、抗氧化活性以及挥发性成分的变化。结果表明,与对照组相比,接种乳酸菌可加快羊奶酒在发酵初期总糖含量的下降,其中添加发酵乳杆菌的羊奶酒发酵1 d后的总糖含量下降最快,由469.46 g/L降低至210.41 g/L。添加乳酸菌发酵会使羊奶酒的ABTS+自由基清除能力与羟自由基清除能力显著提高(P<0.05),其中嗜酸乳杆菌发酵羊奶酒的ABTS+自由基清除能力与羟自由基清除能力最高,分别比对照组高9.94%、37.75%。此外,接种嗜酸乳杆菌发酵的羊奶酒挥发性化合物含量最高(2688.30 mg/L)。乳酸菌与酵母菌混合发酵减少了醇类和酸类物质含量,使羊奶酒的膻味降低,同时生成了环戊酮、乳酸乙酯、己酸乙酯等新的挥发性物质,赋予了羊奶酒新的香气特征。嗜酸乳杆菌和酿酒酵母混合发酵羊奶酒不仅创新了羊奶酒的酿造工艺,还为羊奶酒的脱膻处理提供了理论依据。

复合乳酸菌发酵草本调味醋的酿造工艺研究

发酵调味醋一直有“养生饮料”、“保健醋品”等美誉。该研究以药食同源的蒲公英根、叶以及灯笼草为原料,利用乳酸菌发酵,通过总酸含量、沉淀率等指标确定调味醋比例,优化发酵工艺,对发酵液进行调配及稳定性研究,从而研制出口感较佳、营养成分丰富且抗氧化性良好的蒲公英-灯笼草复合调味醋。结果表明,在蒲公英根∶蒲公英叶∶灯笼草汁为5∶2∶0.2的混合比例下,乳酸菌接种量3%、蔗糖添加量8%、柠檬酸添加量0.02%、CMC-Na添加量0.05%、明胶添加量0.15%、琼脂添加量0.05%、35℃发酵65 h为最佳工艺条件。在此发酵条件下,各类抗氧化活性物质增长迅速,具有显著的抗氧化性、在保健调味醋及醋饮料领域具有很好的发展前景。

发酵大弹涂鱼饲料乳酸菌的筛选鉴定及其发酵条件优化

从大弹涂鱼肠道中分离适用于发酵大弹涂鱼饲料的优良乳酸菌,并优化其发酵条件。采用钙溶圈法分离纯化得到22株乳酸菌,通过对其产酸能力、抑菌能力、耐胆盐能力、耐酸能力、发酵饲料性能进行综合评价,得到一株发酵性能良好的乳酸菌菌株Bp1。结合生化结果和16S rRNA进化分析,菌株Bp1鉴定发酵黏液乳杆菌。以市售普通大弹涂鱼饲料为原料,加入Bp1菌株并对接种量、发酵温度、初始含水量、发酵时间四个因素进行正交试验,确定最佳发酵工艺为接种量2.0%、发酵温度37℃、初始含水量60%、发酵时间3 d,最优条件下发酵饲料的粗蛋白含量为38.15%。研究结果为大弹涂鱼发酵饲料的制备提供了理论基础。

豌豆乳乳酸菌发酵工艺优化及其品质特性研究

为研制和开发营养性新型豌豆乳,以豌豆粉为原材料,使用植物乳杆菌发酵工艺制备豌豆乳,通过单因素试验研究发酵时间、温度、接种量和豌豆粉添加量对豌豆发酵乳中活菌数的影响,以活菌数为指标进行响应面试验对豌豆乳发酵工艺进行优化,运用质构仪测定豌豆发酵乳的质构,对不同发酵时间条件下的豌豆发酵乳进行感官评价。结果表明:最优工艺为发酵温度36℃、乳酸菌接种量0.10%、豌豆粉添加量5.83%、发酵时间24 h;乳酸菌接种量和发酵温度、发酵温度和时间交互作用对活菌数影响极显著;在最优发酵条件下活菌数的对数为9.05,总酚含量为281.77 mg/L,总糖含量为86.01 mg/mL,淀粉含量为21.94 mg/g,蛋白含量为1.10 g/100 g;与发酵前相比,发酵后豌豆乳抗氧化活性显著增强,DPPH清除率可达66.83%;豌豆发酵乳的总糖、总酚含量、活菌数、抗氧化活性及淀粉含量均高于大豆发酵乳;豌豆发酵乳的黏附性、内聚性、硬度、弹性及咀嚼性显著提升;发酵24 h的豌豆乳感官评分最高。植物乳酸菌发酵能够提升豌豆乳的营养成分和品质特性,研究结果为豌豆开发利用提供新的途径。

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。

豆乳发酵中乳酸菌的作用分析

豆乳作为一种营养丰富的植物蛋白饮品,近年来受到越来越多消费者的青睐。为了进一步提升豆乳的口感和营养价值,发酵处理成为了一种重要的加工方式。本文深入分析乳酸菌在豆乳发酵过程中的具体作用,探讨其对豆乳品质、口感及营养价值的提升效果。

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。

具有抑菌活性乳酸菌的分离、鉴定及其生长特性研究

以枯草芽孢杆菌(Bacillus subtilis)、大肠杆菌(Escherichia coli)、普通变形杆菌(Proteus vulgaris)为指示菌,采用传统培养分离法结合牛津杯法从传统发酵食品中筛选具有抑菌活性的乳酸菌,对其发酵上清液的稳定性及生长特性进行研究,并通过分子生物学技术对其进行鉴定。结果表明,筛选得到4株具有良好抑菌活性的乳酸菌菌株,编号为Y1、Y4、Y14、Y15。4株菌株的发酵上清液均能抑制3种指示菌的生长,其中,菌株Y1抑菌活性较好,对3种指示菌的抑菌圈直径均>13 mm,其发酵上清液在60℃、100℃处理后的抑菌活力>69%;菌株Y1、Y14、Y15发酵上清液经酸碱处理后再调回后抑菌活力仍>67%。4株菌株的生长曲线与产酸特性和抑菌活性存在生长偶联相关性,进入稳定期后,抑菌圈直径趋于稳定,可在发酵12~18 h时终止发酵。4株菌株均在pH 5.0~7.0时生长良好,最适生长pH均为6.0,其中菌株Y15耐酸性及耐渗透性较好,菌株Y1耐碱性较好。经鉴定,菌株Y1和Y4均为发酵乳杆菌(Lactobacillus fermentum),菌株Y14和Y15均为植物乳杆菌(Lactiplantibacillus plantarum)。