Functional characteristics of Lactobacillus spp. from traditional Maasai fermented milk products in Kenya

In this study functional characteristics of 23 representative Lactobacillus strains isolated from the Maasai traditional fermented milk 'Kule naoto' were determined. The Lb. acidophilus group strains showed resistance to gastric juice and bile. In addition, some Lb. acidophilus strains expressed bile salt hydrolase activity, and had ability to assimilate cholesterol in vitro. In-vitro adhesion to HT29 MTX cells of up to 70% was recorded. Lb. fermentum strains showed almost 100% survival under simulated stomach acidic conditions and physiological salt concentrations of bile salts, hydrophobicity values were over 80%. Most strains of the Lb. casei and Lb. acidophilus groups showed aggregation abilities of above 50%. Many strains expressed a protective effect against N-methyl-N'-nitro-N-nitrosoguanidine induced DNA damage according to the 'comet assay' and none was virulent. The antibiotic minimum inhibitory concentration of selected strains was established. According to these results, the Lactobacillus spp associated with 'Kule naoto', contain potentially probiotic (functional) strains.     

传统乳制品中潜在益生植物乳杆菌的体外筛选

对从内蒙古牧区乳制品中分离到的29株植物乳杆菌的耐酸性（pH=3．0）、耐胆汁性（质量浓度3g／L牛胆酸钠）、抗菌活性进行了系统性研究。结果表明，有10株菌具有较好的耐酸耐胆盐特性，结合抗菌特性及黏附性试验结果，菌株WZ47-1，WZ32-2-1和WH13-2有可能成为潜在益生菌菌株。     

传统发酵牦牛酸乳中益生性乳酸菌的体外筛选

为获得具有潜在益生特性的乳酸菌,实验以抗人工胃液、胆盐中生长效率和细胞表面疏水性为筛选指标,对羊八井地区传统发酵牦牛酸乳中分离出的38株乳酸菌进行体外筛选。最终通过测定结果综合比较得出菌株编号为YBJ-3、YBJ-11、YBJ-15、YBJ-17、YBJ-30和YBJ-33乳酸菌的益生特性较好,其中4株乳酸菌抗人工胃液能力大于90%,在胆盐中良好生长。通过16S r DNA序列分析鉴定,菌株编号YBJ-3为屎肠球菌(Enterococcus faecium)、YBJ-11为发酵乳杆菌(Lactobacillus fermentum)、YBJ-15为耐久肠球菌(Enterococcus durans)、YBJ-17为植物乳杆菌(Lactobacillus plantarum)、YBJ-30为植物乳杆菌(Lactobacillus plantarum)、YBJ-33为干酪乳杆菌(Lactobacillus casei)。     

Physicochemical analysis of non-fermented probiotic milk with probiotic Lactobacillus plantarum Ln1 isolated from Korea traditional fermented food

Food Science and Biotechnology - The objective of this study was to develop a non-fermented probiotic milk that maintains its physicochemical properties, microbial properties, antioxidant activity,...     

Potential probiotic Lactobacillus strains from fermented sausages: Further investigations on their probiotic properties

A rational selection of probiotic microorganisms is an important challenge and requires the definition of fundamental information about the physiology and genetics of candidate strains. In this study, selected Lactobacillus (Lact.) strains already characterized in a previous study for their capability to resist low pH and to grow in conditions simulating the intestinal environment, were further investigated to explore their probiotic properties, such as the adhesion capability to intestinal human Caco-2 cell lines and their growth behaviour in the presence of various prebiotic carbohydrates. At first 25 Lactobacillus strains were characterized by pulsed field gel electrophoresis using the endonuclease NotI. Among them, 13 strains belonging to the Lact. plantarum-group were identified at species level by a multiplex PCR assay. Subsequently 11 Lactobacillus strains showing different PFGE restriction pattern and the best acid- and bile-resistances, were chosen to investigate their in vitro adhesion capability to human intestinal epithelial cells and their fermentation properties of five prebiotic substances (FOS, Inulin, IMO, GOS and lactulose) at a concentration of 2%. The 11 strains analysed in this study possessed good adhesion capability to Caco-2 cell layers and, in particular, the eight strains belonging to the Lact. plantarum-group showed the higher final number of viable adhering cells. Moreover a species-related fermentative behaviour was pointed out and the strain Lact. paracasei EL7 was the only one able to grow in the presence of all prebiotics tested. In conclusion the strains of Lactobacillus studied in this research could be further investigated to assess possible in vivo human health benefits.     

分离自传统发酵乳制品中具有优良发酵特性的保加利亚乳杆菌的筛选

以分离自传统发酵乳制品中的11株德氏乳杆菌保加利亚亚种(Lactobacillus delbeueckii subsp.bulgaricus)为研究对象,通过全脂乳单菌发酵,对其发酵乳的发酵时间、pH值、滴定酸度、乙醛和双乙酰含量等指标进行分析,最终筛选出1株具有优良发酵特性的菌株IMAU20775。该菌株发酵时间较短,后酸化能力弱,产乙醛能力较好,产双乙酰能力较稳定,适于进一步作为发酵剂菌种的筛选和应用研究。     

Use of molecular tools to characterize Lactobacillus spp. isolated from Greek traditional fermented sausages

In this study, our purpose was to molecular characterize Lactobacillus strains isolated from naturally fermented sausages, produced in three different processing plants in continental Greece, in order to investigate the differences of strains coming from different producing areas. Three-hundred and thirty eight strains were isolated throughout the fermentation periods on MRS. They were identified by species-specific PCR and sequencing of partial 16S rRNA gene. The results obtained highlighted that the main populations involved in the fermentations studied belonged to the species Lactobacillus sakei, Lactobacillus plantarum and Lactobacillus curvatus. However, for each of the fermentations, the percentage of isolation for the three main species was different. Molecular characterization of these strains was performed by RAPD-PCR with primer M13 and cluster analysis was applied to define relations and degrees of similarities between strains. This analysis led to the understanding that some strains were plant-specific, whereas others shared a degree of homology independently of the provenience. This evidence is highlighting the capability of the strains to adapt to specific production condition, becoming the main responsible for the transformations, thereby influencing the final characteristics of the sausages.     

Assessment of potential probiotic properties of Lactobacillus spp., Lactococcus spp., and Pediococcus spp. strains isolated from kefir

In this study, the metabolic activities (in terms of quantities of the produced lactic acid, hydrogen peroxide, and exopolysaccharides) of 8 strains of Lactobacillus spp., Lactococcus spp., and Pediococcus spp., were determined. Lactic acid levels produced by strains were 8.1 to 17.4 mg/L. The L. acidophilus Z1L strain produced the maximum amount (3.18 μg/mL) of hydrogen peroxide. The exopolysaccharides (EPS) production by the strains was ranged between 173 and 378 mg/L. The susceptibility of 7 different antibiotics against these strains was also tested. All strains were found to be sensitive to ampicillin. The tolerance of the strains to low pH, their resistance to bile salts of strains, and their abilities to autoaggregate and coaggregate with Escherichia coli ATCC 11229 were also evaluated. High EPS-producing strains showed significant autoaggregation and coaggregation ability with test bacteria (P < 0.01). A correlation also was determined between EPS production and acid-bile tolerance (P < 0.05). EPS production possibly affects or is involved in acid-bile tolerance and aggregation of Lactobacillus spp., Lactococcus spp., and Pediococcus spp. strains and supports the potential of L. acidophilus Z1L strain as new probiotic.     

Identification of Lactobacillus spp. in probiotic products by real-time PCR and melting curve analysis

A rapid and reliable technique for identifying the strains of lactic acid bacteria (LAB) was developed in this study, and the 16S ribosomal RNA gene (16S rRNA gene) was used as the target. Several species-specific primer pairs were designed based on the variability of 16S rRNA sequence(s) for differentiating 5 strains of lactobacilli which were added into probiotic products in Taiwan. It was simple to identify Lactobacillus acidophilus and L. delbrueckii by species-specific primers, but it could not be used to distinguish L. casei, L. paracasei and L. rhamnosus. Another PCR approach was developed with hybridization probes which were designed according to the difference among the 16S rRNA genes of L. casei, L. paracasei and L. rhamnosus, and melting curve analysis of the hybridization probe was used to distinguish them. It was found that this approach could identify L. paracasei and L. rhamnosus correctly but not separate L. paracasei from L. casei, the result was due to both of them had the same 16S rRNA sequence. These results suggest that melting curve analysis of PCR approach in this study is a rapid, simple and accurate method in distinguishing the closely related strains of lactobacilli.     

传统发酵肉制品中优良菌种分离筛选的研究进展

传统发酵肉制品中广泛存在着优良的自然菌种,可以作为分离、筛选优良菌种的来源。本文综述了国内外从传统发酵肉制品中分离筛选优良菌种的研究现状,并对这些菌种作为发酵肉制品发酵剂的应用前景进行了展望。     

Cellular injuries of spray-dried Lactobacillus spp. isolated from kefir and their impact on probiotic properties

The injuries caused by spray drying (SD) of three potential probiotic lactobacilli isolated from kefir grains and the impact on some probiotic properties, were evaluated. Results demonstrated that Lactobacillus plantarum 83114 and L. kefir 8321 showed a slight reduction of viability (0.11 and 0.29 log CFU/ml respectively) after SD process, and L. kefir 8348 was found to be more sensitive to the process with a reduction in viability of 0.70 log CFU/ml. Neither membrane damage, evaluated by increased sensitivity to NaCl, lysozyme, bile salt and penicillin G, nor changes in acidifying activity in MRS and milk by lactobacilli were detected after SD. L. plantarum 83114 and L. kefir 8321 after SD did not lose their capacity to adhere to intestinal cells. Nevertheless, L. kefir 8348 showed a significant loss of adhesion capacity after SD. In addition, rehydrated spray-dried L. kefir 8321 retained the ability to protect against Salmonella invasion of intestinal cells. This effect was observed when L. kefir is co-incubated with Salmonella before invasion assay.This work shows that the membrane integrity evaluated by indirect methods and some probiotic properties of lactobacilli isolated from kefir did not change significantly after SD, and these powders could be used in functional foods applications.     

Lactobacillus fermentum strains from human breast milk with probiotic properties and cholesterol-lowering effects

Food Science and Biotechnology - The study aimed to identify two lactic acid bacteria from human breast milk and evaluate for their probiotic potential. Lactobacillus fermentum strains showed...     

传统发酵蔬菜中乳杆菌的产酸性能的研究

以从陕西传统发酵蔬菜中筛选出的12株乳杆菌为研究对象,通过测定其在MRS液体培养基中的总酸和pH值的变化以及在牛乳中的酸度和pH值的变化,对其产酸性能进行比较,最终得出3株产酸能力较强的菌株,其分别是c4、z2和h2。     

Potential probiotic characteristics of Lactobacillus and Enterococcus strains isolated from traditional dadih fermented milk against pathogen intestinal colonization

Traditional fermented buffalo milk in Indonesia (dadih) has been believed to have a beneficial impact on human health, which could be related to the properties of the lactic acid bacteria (LAB) involved in its fermentation process. In previous studies, it was discovered that strains of dadih lactic isolates possessed some beneficial properties in vitro. In the present study, the adhesion capacity of specific LAB isolates from dadih to intestinal mucus was analyzed. Further, the ability to inhibit model human pathogens and displace them from mucus was assessed. The adhesion of tested LAB strains was strain-dependent and varied from 1.4 to 9.8%. The most adhesive Lactobacillus plantarum strain was IS-10506, with 9.8% adhesion. The competition assay between dadih LAB isolates and pathogens showed that a 2-h preincubation with L. plantarum at 37 degrees C significantly reduced pathogen adhesion to mucus. All tested LAB strains displaced and inhibited pathogen adhesion, but the results were strain-specific and dependent on time and pathogen strains. In general, L. plantarum IS-10506 showed the best ability against pathogen adhesion.     

我国传统发酵制品来源乳杆菌黏附相关表面特性研究

为了研究乳杆菌黏附相关表面特性,以传统发酵制品中分离的10株乳杆菌为研究对象,测定了菌株的疏水性、自聚力、对致病菌的共聚力及Caco-2细胞体外黏附能力。结果表明,所有受试菌株中,菌株C88的疏水性和自聚力均明显高于其它菌株。菌株K25对大肠杆菌和志贺氏菌有较强的共聚力,分别达到48.05%和53.76%。而菌株C88对金黄色葡萄球菌和沙门氏菌的共聚力最高,分别为40.03%和34.09%。另外,采用2M胍-HCl和5MLiCl方法提取了菌株C88的表面蛋白,经SDS-PAGE电泳分析发现,表面蛋白集中在25~45 ku之间。与其他受试菌株相比,菌株C88和K25具有较好的体外黏附特性,可用作益生菌进一步研究开发。     

Potato juice fermented with Lactobacillus casei as a probiotic functional beverage

This study was conducted to evaluate probiotic potato juice as a potential substrate for the production of Lactobacillus casei, and the change in the functionality of potato juice was monitored during fermentation. L. casei grew well in potato juice without nutrient supplementation, and lactic acid bacteria of fermented ‘Haryoung’ juice reached 1.7×10⁹ CFU/mL after a 48 h fermentation. DPPH radical scavenging activities of the potato juices decreased after a 72 h fermentation, but fermented colored potato juice still maintained >50% radical scavenging activity. The survival rate of L. casei fermented in’ Haryoung’ juice was 89.0% after exposure to an acidic condition, and L. casei in all fermented potato juice samples showed the ability (50–85%) to survive in the presence of bile. These results suggest that fermented potato juice might serve as a probiotic functional beverage for vegetarians or consumers who are allergic to dairy products.     

In vitro characterisation of probiotic properties of Enterococcus faecium and Enterococcus durans strains isolated from raw milk and traditional dairy products

In this study, some probiotic characteristics such as antimicrobial activity, vancomycin resistance, growth ability at pH, resistance to bile salts, bile salt deconjugation and hydrophobicity of 30 Enterococcus faecium and Enterococcus durans strains isolated and identified from raw milk and various dairy products were investigated. According to the study results, antimicrobial activity profiling, pH and bile salt resistance and bile salt deconjugation ability of Enterococcus strains varied depending on the species and strains and all the strains showed resistance to the tested bile salt concentrations. It was concluded that the E. faecium and E. durans strains tested showed probiotic characteristics and have the potential to be used in food production.