Characterization of macrophage-activating lactic acid bacteria isolated from Mukeunji

Food Science and Biotechnology - Lactic acid bacteria (LAB) were reported to comprise the majority of the bacterial population in mukeunji, a long-fermented kimchi. This current study investigated...     

Tyramine production among lactic acid bacteria and other species isolated from kimchi

Lactic acid bacteria (LAB) are naturally found in fermented vegetable products. The ability of 230 kimchi bacterial isolates was investigated to produce tyramine by biochemical and genetic methods. The production of tyramine was determined by thin-layer chromatography (TLC) and high-performance liquid chromatography (HPLC). The presence of the gene encoding the corresponding tyrosine decarboxylase was also determined by PCR assay. After the production of tyramine was confirmed by chromatographic and molecular methods, the bacterial isolates producing the amine were identified by 16S rRNA gene sequence and species-specific PCR analyses. Only a small proportion of the bacterial isolates (14/230 isolates) decarboxylated tyrosine in vitro. All of the 14 bacterial isolates that produced tyramine were shown to possess the tdc gene, indicating that a positive correlation existed between the production of tyramine and the presence of the corresponding decarboxylase gene. The 14 isolates included three LAB species and one other species: Lactobacillus brevis (six), Lactobacillus curvatus (four), Leuconostoc mesenteroides (two), and Staphylococcus hominis (two). This study demonstrated that only a small proportion of LAB and other microbiota growing in kimchi had the ability to produce tyramine.     

Probiotic lactic acid bacteria detoxify N-nitrosodimethylamine

Humans can be exposed to N-nitroso compounds (NOCs) due to many environmental sources, as well as endogenous formation. The main nitrosamine found in food products and also synthesised in vivo by intestinal microbiota is N-nitrosodimethylamine (NDMA). It can cause cancer of the stomach, kidney and colon. The effect of four probiotic Lactobacillus strains on NDMA was studied under different culture conditions (24 h in MRS, 168 h in modified MRS N, and 168 h in phosphate buffer). HPLC and GC-TEA methods were used for NDMA determination in supernatants. The influence of lactic acid bacteria on NDMA genotoxicity was investigated by means of the comet assay. Additionally, the effect of NDMA (2–100 µg ml^–1) on the growth and survival of the probiotic strains was studied. The results indicate that the bacteria decreased NDMA concentration by up to 50%, depending on the culture conditions, time of incubation, NDMA concentration, pH and bacterial strain. Lb. brevis 0945 lowered the concentration and genotoxicity of NDMA most effectively by up to 50%. This could be due to either adsorption or metabolism. The growth and survival of the bacteria was not affected by any of the tested NDMA concentrations.     

风干香肠中乳酸菌的分离鉴定及益生特性研究

由风干香肠中分离纯化得到的3株乳酸菌ORC2、QM7和QM8,均能产乳酸、革兰氏染色阳性、接触酶阴性。经系统发育分析,结合菌落形态、细胞形态、生化反应试验,确定菌株ORC2和QM7为肠膜明串珠菌,QM8为柠檬明串珠菌。乳酸菌ORC2、QM7和QM8均能降低培养基中的胆固醇,且对·OH、DPPH·和O-2·有一定的清除能力,其清除率都与细胞浓度呈正相关。在细胞浓度为5×108CFU/mL时,菌株ORC2对·OH的清除率最高,为65.36%;菌株QM8对DPPH·的清除率最高,为61.21%;而对O-2·的清除率最高的菌株为QM7,达到75.70%。菌株QM7在培养96 h能清除最多的胆固醇,清除率为51.2%。     

Heterofermentative lactic acid bacteria dominate in Korean commercial kimchi

Food Science and Biotechnology - Lactic acid bacterial communities in kimchi prepared by representative Korean kimchi companies were investigated using a pyrosequencing method. The pH values of 9...     

Probiotic and antioxidant properties of C30 carotenoid-producing Lactiplantibacillus plantarum isolated from kimchi

Food Science and Biotechnology - This study focuses on the development of functional probiotics using caroteonid-producing lactic acid bacteria (LAB) with antioxidant properties. Thirty LAB strains...     

Rice yogurt with various beans fermented by lactic acid bacteria from kimchi

Food Science and Biotechnology - In this study, the rice yogurt with various beans was developed using a mixture of rice saccharification solution as an artificial sweetener substitute and bean...     

锦州虾油小黄瓜中耐盐乳酸菌的生物性能研究

对从锦州虾油小黄瓜中分离筛选的6株耐盐乳酸菌进行抗氧化和形成风味物质等生物性能研究,结果表明菌株L7对羟自由基、DPPH自由基、超氧阴离子自由基清除作用明显,清除率均分别为38.56％、33.65％、36.65％;对Fe3+有较强的还原能力,与还原能力成正比的吸光度值为0.875;在发酵过程中,形成风味物质乙醛和双乙酰分别为5.02μg/mL和3.65μg/mL.通过特征性耐盐性乳酸菌的生物性能分析,获得高活性的菌株L7,对改善锦州虾油黄瓜产品品质具有一定的应用前景.     

Diversity of lactic acid bacteria population in ripened Parmigiano Reggiano cheese

The diversity of dominant lactic acid bacteria population in 12 months ripened Parmigiano Reggiano cheeses was investigated by a polyphasic approach including culture-dependent and independent methods. Traditional plating, isolation of LAB and identification by 16S rDNA analysis showed that strains belonging to Lactobacillus casei group were the most frequently isolated. Lactobacillus helveticus, Lactobacillus delbrueckii subsp. lactis, Lactobacillus parabuchneri, and Lactobacillus buchneri species were detected with lower frequency. PCR-denaturing gradient gel electrophoresis (DGGE) applied to DNA extracted directly from cheese samples and sequencing of rDNA amplicons confirmed the complex microbiological pattern of LAB in ripened Parmigiano Reggiano cheeses, with the significant exception of the Lactobacillus fermentum species, which dominated in several samples, but was not detected by cultivation. The present combination of different approaches can effectively describe the lactic acid bacteria population of Parmigiano Reggiano cheese in advanced stages of ripening, giving useful information for elucidating the role of LAB in determining the final cheese quality.     

Probiotic spectra of lactic acid bacteria (LAB)

Lactic acid bacteria (LAB) and their probio-active cellular substances exert many beneficial effects in the gastrointestinal tract. LAB prevent adherence, establishment, and replication of several enteric mucosal pathogens through several antimicrobial mechanisms. LAB also release various enzymes into the intestinal lumen and exert potential synergistic effects on digestion and alleviate symptoms of intestinal malabsoption. Consumption of LAB fermented dairy products with LAB may elicit antitumor effects. These effects are attributed to the inhibition of mutagenic activity; decrease in several enzymes implicated in the generation of carcinogens, mutagens, or tumor-promoting agents; suppression of tumors; and the epidemiology correlating dietary regimes and cancer. Specific cellular components in LAB strains seem to induce strong adjuvant effects including modulation of cell-mediated immune responses, activation of reticuloendothelial system, augmentation of cytokine pathways and regulation of interleukins, and tumor necrosis factors. Oral administration of LAB is well tolerated and proven to be safe in 143 human clinical trials and no adverse effects were reported in any of the total 7,526 subjects studied during 1961-1998. In an effort to decrease the reliance on synthetic antimicrobials and control the emerging immunocompromised host population, the time has come to carefully explore the prophylactic and therapeutic applications of probiotic LAB.     

Technological and safety properties of lactic acid bacteria isolated from Spanish dry-cured sausages

Technological and safety-related properties were analyzed in lactic acid bacteria isolated from Spanish dry-cured sausages in order to select them as starter cultures. In relation to technological properties, all the strains showed significative nitrate reductase activity; Lactobacillus plantarum, Lactobacillus paracasei and 52% of the Enterococcus faecium strains showed lipolytic activity and only Lactobacillus sakei strains (43%) were able to form biofilms. Related to safety aspects, E. faecium strains were the most resistant to antibiotics, whereas, L. sakei strains were the most sensitive. In relation to virulence factors, in the E. faecium strains analyzed, only the presence of efaA gene was detected. The analysis of biogenic amine production showed that most E. faecium strains and L. sakei Al-142 produced tyramine. In conclusion, L. paracasei Al-128 and L. sakei Al-143 strains possess the best properties to be selected as adequate and safe meat starter cultures.     

Probiotic lactic acid bacteria from Kung‐Som: isolation,screening, inhibition of pathogenic bacteria

Lactic acid bacteria (LAB) were isolated from Kung‐Som at various fermentation periods. Only ten strains, named D2SM22, D6SM3, D6SM24, D6SM26, D8SM21, D10SM5, D10SM11, D10SM16, D10SM20 and D16SM26 showed a survival rate of more than 50% under the simulated gastric juice. After being subjected to simulated gastric juice, four strains (D6SM3, D8SM21, D10SM16 and D10SM20) showed a survival rate of more than 50% in simulated small intestinal juices. Growth of strain D6SM3, D8SM21 and D10SM16 under micro‐aerobic and anaerobic conditions was not different. Tested pathogenic strains (Escherichia coli, Staphylococcus aureus, Bacillus cereus, Vibrio parahaemolyticus and Salmonella sp.) were inhibited by probiotic LAB. However, none of strains could produce bacteriocins. All strains were identified as Lactobacillus plantarum. No differences in pH, acidity, LAB count and liking scores between Kung‐Som produced with starter culture and conventional method were observed (P > 0.01).     

泡菜中降解亚硝酸盐乳酸菌的筛选及生物学特性研究

为降低泡菜发酵过程中亚硝酸盐含量,从泡菜中筛选出6株降解亚硝酸盐的乳酸菌。根据培养特征、菌体特征和16S r DNA同源比对分析,JYF1、JYF2、JYF5和JYF6鉴定为植物乳杆菌; JYF3和JYF4鉴定为发酵乳杆菌,选取JYF2和JYF3研究其生物学特性。结果表明:JYF2和JYF3发酵的泡菜最终p H值为3,自然发酵的最终p H值为3. 5;泡菜发酵至第8天,JYF2和JYF3发酵的泡菜亚硝酸盐含量分别为1. 8和2 mg/kg,低于自然发酵组6. 3 mg/kg; JYF2和JYF3在p H 3～4时,存活率> 60%;胆盐质量浓度在0. 01～0. 03 g/L时,JYF2和JYF3的存活率在50%以上; JYF2和JYF3对革兰氏阳性菌的抑制作用大于革兰氏阴性菌; JYF2和JYF3对不同抗生素有不同的敏感性。本研究筛选的JYF2和JYF3具有良好的生物学特性,可为生产低亚硝酸盐泡菜提供优良发酵菌株。     

Characterization of lactic acid bacteria isolated from Bukuljac, a homemade goat's milk cheese

The Bukuljac cheese is traditionally homemade cheese, produced from heat-treated goat's milk without the addition of any bacterial starter culture. The presence of lactic acid bacteria (LAB) in Bukuljac cheese has been analyzed by using a polyphasic approach including microbiological and molecular methods such as rep-PCR with (GTG)5 primer. Lactobacillus paracasei subsp. paracasei represents a dominant strain in the microflora of analyzed cheese. Out of 55 Gram-positive and catalase-negative isolates, 48 belonged to L. paracasei subsp. paracasei species. Besides lactobacilli, five Lactococcus lactis subsp. lactis and two Enterococcus faecalis were found. Results of PCR-denaturing gradient gel electrophoresis (DGGE) of DNA extracted directly from the fresh cheese revealed the presence of Leuconostoc mesenteroides. Only lactobacilli showed a high proteolytic activity and hydrolyzed alpha(s1)- and beta-caseins. They are also producers of diacetyl. In addition, 34 out of 55 isolates, all determined as lactobacilli, showed the ability of auto-aggregation. Among 55 isolates, 50 also exhibited antimicrobial activity.     

Functional properties of lactic acid bacteria isolated from ethnic fermented vegetables of the Himalayas

A total of 94 strains of Lactic acid bacteria (LAB), previously isolated from ethnic fermented vegetables and tender bamboo shoots of the Himalayas, were screened for functional properties such as acidification capacity, enzymatic activities, degradation of antinutritive factors and oligosaccharides, production of biogenic amines, hydrophobicity and adherence to mucus secreting HT29 MTX cells. Strong acidification and coagulation activities of LAB strains were recorded. Most of the LAB strains showed antimicrobial activities against the used indicator strains; however, only Lb. plantarum IB2 (BFE 948) isolated from inziangsang, a fermented leafy vegetable product, produced a bacteriocin against Staphylococcus aureus S1. LAB strains showed enzymatic activities and also degraded oligosaccharides. Almost all the strains of LAB were non-producers of biogenic amines except few strains. Some strains of Lb. plantarum showed more than 70% hydrophobicity. Adherence to the mucus secreting HT29 MTX cells was also shown by seven strains indicating their probiotic nature.     

Probiotic potential of lactic acid bacteria from fermented Malaysian food or milk products

This study investigated the probiotic characteristics of lactic acid bacteria (LAB) isolated from 14 Malaysian fermented food or milk products. In total, 22.3% (121 of 542) of the LAB isolated from the local fermented products exhibited antibacterial activity against Micrococcus luteus. Twelve LAB that demonstrated better antibacterial activity against M. luteus as compared to a commercial strain Lactobacillus casei strain Shirota (LABPC) were selected for further characterisation. Based on 16S rRNA gene sequence, the LAB were identified as pediococci (seven) and lactobacilli (five). All 12 LAB showed bile tolerance, but only eight were acid tolerant at pH ≥ 3.0. The highest level of adhesion to HT‐29 cells was observed among the Lactobacillus sp. LAB 1 and 10. The LAB also showed antimicrobial activity against Escherichia coli and Staphylococcus aureus through the production of organic acids. LAB isolated from Malaysian fermented food and milk products, especially fermented tapioca, contains potential probiotic candidates.     

分离自传统发酵肉制品乳酸菌的发酵特性研究

对分离自传统发酵肉制品的植物乳杆菌(La04)和米酒乳杆菌(La22)的特性进行了研究.结果表明:两株菌均有良好的生长特性、产酸能力、耐盐能力和抑菌性能,具有分解亚硝酸盐的能力,但无蛋白质分解能力.最适生长温度为32～35℃,最适pH为5.5～7.5,具备作为肉用发酵剂的优良特性.