Boza, a natural source of probiotic lactic acid bacteria

Aims: To evaluate the probiotic properties of strains isolated from boza, a traditional beverage produced from cereals. Methods and Results: The strains survived low pH conditions (pH 3·0), grew well at pH 9·0 and were not inhibited by the presence of 0·3% (w/v) oxbile. Cytotoxicity levels of the bacteriocins, expressed as CC₅₀, ranged from 38 to 3776 μg ml^?1. Bacteriocin bacST284BZ revealed high activity (EC₅₀ = 735 μg ml^?1) against herpes simplex virus type 1. Growth of Mycobacterium tuberculosis was 69% repressed after 5 days in the presence of bacST194BZ. Various levels of auto‐cell aggregation and co‐aggregation with Listeria innocua LMG 13568 were observed. Adhesion of the probiotic strains to HT‐29 cells ranged from 18 to 22%. Conclusions: Boza is a rich source of probiotic lactic acid bacteria. All strains survived conditions simulating the gastrointestinal tract and produced bacteriocins active against a number of pathogens. Adherence to HT‐29 and Caco‐2 cells was within the range reported for Lactobacillus rhamnosus GG, a well‐known probiotic. In addition, the high hydrophobicity readings recorded define the strains as good probiotics. Significance and Impact of the Study: Boza contains a number of different probiotic lactic acid bacteria and could be marketed as a functional food product.     

Recent update on lactic acid bacteria producing riboflavin and folates: application for food fortification and treatment of intestinal inflammation

Lactic acid bacteria (LAB), widely used as starter cultures for the fermentation of a large variety of food, can improve the safety, shelf life, nutritional value and overall quality of the fermented products. In this regard, the selection of strains delivering health-promoting compounds is now the main objective of many researchers. Although most LAB are auxotrophic for several vitamins, it is known that certain strains have the capability to synthesize B-group vitamins. This is an important property since humans cannot synthesize most vitamins, and these could be obtained by consuming LAB fermented foods. This review discusses the use of LAB as an alternative to fortification by the chemical synthesis to increase riboflavin and folate concentrations in food. Moreover, it provides an overview of the recent applications of vitamin-producing LAB with anti-inflammatory/antioxidant activities against gastrointestinal tract inflammation. This review shows the potential uses of riboflavin and folates producing LAB for the biofortification of food, as therapeutics against intestinal pathologies and to complement anti-inflammatory/anti-neoplastic treatments.     

Nisin‐induced expression of pediocin in dairy lactic acid bacteria

Aims: To test whether a single vector, nisin‐controlled expression (NICE) system could be used to regulate expression of the pediocin operon in Streptococcus thermophilus, Lactococcus lactis subsp. lactis and Lactobacillus casei. Methods and Results: The intact pediocin operon was cloned immediately into pMSP3535 downstream of the nisA promoter (PnisA). The resulting vector, pRSNPed, was electrotransformed into Strep. thermophilus ST128, L. lactis subsp. lactis ML3 and Lact. casei C2. Presence of the intact vector was confirmed by PCR, resulting in the amplification of a 0·8‐kb DNA fragment, and inhibition zones were observed for all lactic acid bacteria (LAB) transformants following induction with 50 ng ml^?1 nisin, when Listeria monocytogenes Scott A was used as the target bacterium. Using L. monocytogenes NR30 as target, the L. lactis transformants produced hazy zones of inhibition, while the Lact. casei transformants produced clear zones of inhibition. Zones of inhibition were not observed when the Strep. thermophilus transformants were tested against NR30. Conclusions: The LAB hosts were able to produce enough pediocin to inhibit the growth of L. monocytogenes Scott A; the growth of L. monocytogenes NR30 was effectively inhibited only by the Lact. casei transformants. Significance and Impact of the Study: This is the first time that the NICE system has been used to express the intact pediocin operon in these LAB hosts. This system could allow for the in situ production of pediocin in fermented dairy foods supplemented with nisin to prevent listeria contamination.     

UNC5B receptor deletion exacerbates DSS‐induced colitis in mice by increasing epithelial cell apoptosis

The netrin-1 administration or overexpression is known to protect colon from acute colitis. However, the receptor that mediates netrin-1 protective activities in the colon during colitis remains unknown. We tested the hypothesis that UNC5B receptor is a critical mediator of protective function of netrin-1 in dextran sodium sulfate (DSS)-induced colitis using mice with partial deletion of UNC5B receptor. DSS colitis was performed in mice with partial genetic UNC5B deficiency (UNC5B^+/− mice) or wild-type mice to examine the role of endogenous UNC5B. These studies were supported by in vitro models of DSS-induced apoptosis in human colon epithelial cells. WT mice developed colitis in response to DSS feeding as indicated by reduction in bw, reduction in colon length and increase in colon weight. These changes were exacerbated in heterozygous UNC5B knockout mice treated with DSS. Periodic Acid-Schiff stained section shows damages in colon epithelium and mononuclear cell infiltration in WT mice, which was further increased in UNC5B heterozygous knockout mice. This was associated with large increase in inflammatory mediators such as cytokine and chemokine expression and extensive apoptosis of epithelial cells in heterozygous knockout mice as compared to WT mice. Overexpression of UNC5B human colon epithelial cells suppressed DSS-induced apoptosis and caspase-3 activity. Moreover, DSS induced large amount of netrin-1 and shRNA mediated knockdown of netrin-1 induction exacerbated DSS-induced epithelial cell apoptosis. Our results suggest that UNC5B is a critical mediator of cell survival in response to stress in colon.     

降解嘌呤核苷乳酸菌的筛选及益生特性探索

【背景】高尿酸血症是人体内嘌呤代谢紊乱导致的一种慢性代谢疾病,利用乳酸菌降解嘌呤类物质是辅助治疗高尿酸血症的新方法。【目的】筛选高效降解嘌呤核苷的乳酸菌并对其益生特性进行研究。【方法】利用HPLC法评价乳酸菌对肌苷、鸟苷的降解效果。通过药敏性试验、体外耐受性试验及细胞黏附试验研究目标菌株的益生特性。【结果】筛选出一株发酵乳杆菌(Lactobacillus fermentum) SR2-6,对肌苷和鸟苷的降解率分别为99.26%和98.85%。该菌株对青霉素、氯霉素等5种常见抗生素不具备耐药性,在pH 2.0环境下处理4 h后菌株的存活率为76.51%,在饱腹状态下的人工肠液模拟消化4 h后活菌数仍能达到6.85 lg (CFU/mL),对Caco-2细胞的黏附数为(52.29±15.14) CFU/cell。【结论】发酵乳杆菌SR2-6能够高效降解肌苷和鸟苷且具有优良的益生特性,是预防和治疗高尿酸血症的潜在优势菌株,可作为优势菌种资源应用于相关功能产品的开发。     

The survival of silage inoculant lactic acid bacteria in rumen fluid

AIMS: To determine whether lactic acid bacteria (LAB) used in inoculants for silage can survive in rumen fluid (RF), and to identify those that survive best. METHODS AND RESULTS: Twelve commercial silage inoculants were added at 107 CFU ml-1 to strained RF (SRF) taken from dairy cows, with and without 5 g l-1 glucose and incubated in vitro at 39 degrees C. Changes in pH, LAB numbers and fermentation products were monitored for 72 h. In the inoculated RF with glucose, the pH decreased and numbers of LAB increased. The inoculants varied with regard to their effect on pH change and growth. In the SRF, both with and without glucose, the pH values of the inoculated samples were generally higher than those of the uninoculated controls throughout most of the incubation period. This may suggest a positive effect on the rumen environment. CONCLUSIONS: LAB used in silage inoculants can survive in RF in vitro. SIGNIFICANCE AND IMPACT OF THE STUDY: This is the first step in studying the probiotic potential of silage LAB inoculants for dairy cattle. The survival of these LAB in RF may enable them to interact with rumen microorganisms and to affect rumen functionality.     

Screening from pickled vegetables the potential probiotic strains of lactic acid bacteria able to inhibit the Salmonella invasion in mice

Aims: To screen from pickled vegetables the potential probiotic lactic acid bacteria (LAB) strains with antagonistic activity against Salmonella invasion in host. Methods and Results: Probiotic properties including acid and bile tolerance as well as inhibition on pathogenic bacteria were used for screening of LAB strains from pickled vegetables. Two strains, i.e Pediococcus pentosaceus MP12 and Lactobacillus plantarum LAP6, were selected and further assayed for their activities against Salmonella invasion in mouse liver and spleen. For these two LAB strains, strain LAP6 was able to adhere to the mouse intestinal epithelium cells. Conclusions: In screening of the probiotic strains able to inhibit the Salmonella invasion in host, factors other than the adherence to host intestinal epithelium may contribute some roles. Significance and Impact of the Study: Probiotic LAB strains with activity against Salmonella invasion in host could be isolated from vegetable origins. These strains may be used for vegetable processing.     

猪源乳酸菌的分离、鉴定及其生物学特性

【目的】将分离自猪肠道粘膜、食糜和粪便的乳酸菌,通过产乳酸能力、生长性能、耐酸和耐胆盐性能及抑菌能力评价,筛选适应养猪生产的潜在益生特性的菌株。【方法】共分离获得155株乳酸菌纯菌株,从中筛选出4株产酸能力较强的乳酸菌,结合生理生化试验及细菌16S rRNA测序鉴定其种属,评价候选乳酸菌的生长情况、耐酸、耐胆盐及抑菌特性。【结果】综合变色时间(8 h)、pH值(3.9)和乳酸含量(100 mmol/L),筛选出4株(L45、L47、L63和L79)候选菌株,经鉴定依次为罗伊氏乳杆菌、植物乳杆菌、约氏乳杆菌和粪肠球菌。该4株乳酸菌均可在体外快速生长;L47和L79能够耐受pH 2.5的酸性环境,L47能够耐受0.5%胆盐环境;各乳酸菌上清液与指示菌共培养,发现对E coli K88和沙门氏菌均产生了抑制作用,其中L47上清液对指示菌的抑制作用较强。【结论】L47具有较好的产酸性能与生长性能、可耐受猪胃酸和肠道胆盐环境,对E.coli K88和沙门氏菌具有较好的抑制作用,说明该乳酸菌具有潜在的益生特性。     

一株产共轭亚油酸乳酸菌的鉴定及其特性

从酸菜汁中分离筛选到一株产共轭亚油酸(CLA)能力较高的乳酸菌。经鉴定,确定为植物乳杆菌Lactobacliius plantarum。微氧条件可提高CLA的产量,催化亚油酸(LA)生成CLA的酶受着LA的诱导。37℃对细胞生长和CLA生成最为有利。对数生长期为6～12h,18h后进入稳定期。在14～22h,CLA生成量快速增加,24h时达到最高值。该菌的培养物经萃取、甲酯化后,进行了气相色谱分离,生成的CLA产物为c9/t9,c11-CLA和t10,c12-CLA异构体的混合物。     

Influence of lactic acid bacteria on stereoselective degradation of theta‐cypermethrin

The purpose of this study was to investigate the influence of four kinds of Lactic acid bacteria (LAB) on stereoselective degradation of theta‐cypermethrin (CYP), including Lactobacillus plantarum, Lactobacillus casei, Lactobacillus delbrueckii, and Streptococcus thermophilus. An effective analytical method for (±)‐theta‐CYP in medium was developed by high‐performance liquid chromatography with cellulose tris‐(3,5‐dimethylphenylcarbamate) chiral stationary phase. theta‐Cypermethrin was spiked to LAB medium with different inoculation rates and sampled at 0, 2, 8, 24, 36, 48, 72, 120, 168, and 240 hours. The results showed that LAB influenced the half‐lives and enantiomer fractions of theta‐CYP enantiomers, which lead a closer degradation rate between the 2 stereoisomers, and no obvious difference was found among 4 LABs. Besides, the stereoselective degradation of theta‐CYP was closely related to pH. The lower the pH (pH of 3, 5, 7, and 9), the lower the enantiomer fraction (from 4.88 to 6.69). At pH of 3, 7, and 9, significant differences of half‐lives between enantiomers were observed. (?)‐theta‐Cypermethrin decreased faster than (+)‐theta‐CYP under pH of 3, while opposite results were indicated under pH of 7 and 9. Moreover, the acidic condition contributed to the higher chiral configuration stability of (±)‐theta‐CYP. (+)‐Enantiomer was influenced by pH in a greater degree than (?)‐enantiomer.     

Study on the influence of caffeic acid against sodium valproate–induced nephrotoxicity in rats

Renal injury is a hallmark adverse reaction to sodium valproate (SVP), and caffeic acid (CAFF) is a phenolic compound that has anti‐inflammatory and antioxsidant properties. So, this investigation was assessed to evaluate the nephrotoxic potential of SVP and the defensive impact of CAFF against SVP nephrotoxicity. SVP was given at a dose of 500 mg/kg (i.p.) once daily for 2 weeks, while CAFF was given at a dose of 50 mg/kg (orally), simultaneously with SVP. Concurrent treatment with CAFF reduced urea and creatinine, lipid peroxidation (malondialdehyde), tumor necrosis factor alpha (TNF‐α), interferon gamma (IFN‐γ), nuclear factor kappa B (NF‐κB/p65), and transforming growth factor β (TGF‐β) levels. However, with increased glutathione content, CAFF also halted the activated Notch signaling cascade. Furthermore, CAFF suppressed caspase‐3 and inducible nitric oxide synthase expressions. To conclude, on the basis of the results obtained, CAFF proved to protect against SVP‐induced nephrotoxicity via its antioxidant, anti‐inflammatory, and antiapoptotic properties.     

Use of superoxide dismutase and catalase producing lactic acid bacteria in TNBS induced Crohn's disease in mice

Reactive oxygen species are involved in various aspects of intestinal inflammation and tumor development. Decreasing their levels using antioxidant enzymes, such as catalase (CAT) or superoxide dismutase (SOD) could therefore be useful in the prevention of certain diseases. Lactic acid bacteria (LAB) are ideal candidates to deliver these enzymes in the gut. In this study, the anti-inflammatory effects of CAT or SOD producing LAB were evaluated using a trinitrobenzenesulfonic acid (TNBS) induced Crohn's disease murine model. Engineered Lactobacillus casei BL23 strains producing either CAT or SOD, or the native strain were given to mice before and after intrarectal administration of TNBS. Animal survival, live weight, intestinal morphology and histology, enzymatic activities, microbial translocation to the liver and cytokines released in the intestinal fluid were evaluated. The mice that received CAT or SOD-producing LAB showed a faster recovery of initial weight loss, increased enzymatic activities in the gut and lesser extent of intestinal inflammation compared to animals that received the wild-type strain or those that did not receive bacterial supplementation. Our findings suggest that genetically engineered LAB that produce antioxidant enzymes could be used to prevent or decrease the severity of certain intestinal pathologies.     

Infrared attenuated total reflection spectroscopic surface analysis of bovine‐tail intervertebral discs after UV‐light‐activated riboflavin‐induced collagen cross‐linking

The tensile strength of the intervertebral disc (IVD) is mainly maintained by collagen cross‐links. Loss of collagen cross‐linking combined with other age‐related degenerative processes contributes to tissue weakening, biomechanical failure, disc herniation and pain. Exogenous collagen cross‐linking has been identified as an effective therapeutic approach for restoring IVD tensile strength. The current state‐of‐the‐art method to assess the extent of collagen cross‐linking in tissues requires destructive procedures and high‐performance liquid chromatography. In this study, we investigated the utility of infrared attenuated total reflection (IR‐ATR) spectroscopy as a nondestructive analytical strategy to rapidly evaluate the extent of UV‐light‐activated riboflavin (B2)‐induced collagen cross‐linking in bovine IVD samples. Thirty‐five fresh bovine‐tail IVD samples were equally divided into five treatment groups: (a) untreated, (b) cell culture medium Dulbecco's Modified Eagle's Medium only, (c) B2 only, (d) UV‐light only and (e) UV‐light‐B2. A total of 674 measurements have been acquired, and were analyzed via partial least squares discriminant analysis. This classification scheme unambiguously identified individual classes with a sensitivity >91% and specificity >92%. The obtained results demonstrate that IR‐ATR spectroscopy reliably differentiates between different treatment categories, and promises an excellent tool for potential in vivo, nondestructive and real‐time assessment of exogenous IVD cross‐linking.     

一株植物乳杆菌Lp3对高脂模型大鼠的益生作用

【目的】本研究通过构建大鼠高脂结构模型来探究一株植物乳杆菌Lp3的益生作用。【方法】植物乳杆菌Lp3筛选自青藏高原地区传统发酵的牦牛酸奶,初步认定Lp3是一株具有良好耐受力的降胆固醇菌株,且体外益生特性突出,本研究通过建立高脂SD大鼠模型,在饲喂试验动物高脂饲料的同时灌胃植物乳杆菌Lp3,来确定该菌株对试验动物血脂的影响效果,并同时研究其对大鼠肠道菌群、粪便水分、粪便中胆固醇和胆汁酸含量的影响,以及对肝脏组织中的胆固醇(TC)和甘油三酯(TG)的影响。【结果】结果表明,植物乳杆菌Lp3对大鼠没有任何明显的毒副作用,对高脂模型大鼠具有良好的降血脂效果。饲喂高脂饲料并灌喂乳酸菌Lp3组大鼠(HL)的血清总胆固醇、甘油三酯和低密度脂蛋白胆固醇含量较饲喂高脂饲料组(HC)显著减少(P0.05),但是高密度脂蛋白胆固醇的含量变化并不明显。HC组大鼠与HL组及饲喂普通日粮组(对照组)大鼠相比较,HC组大鼠粪便中大肠杆菌数量明显增加,双歧杆菌、乳杆菌数量明显减少。但是灌胃乳酸菌的HL组大鼠的粪便中乳杆菌数略高于对照组,大肠杆菌和双歧杆菌数量和对照组大鼠的基本一致。表明植物乳杆菌Lp3具有维持肠道菌群平衡的作用。此外灌胃乳酸菌后HL组大鼠粪便含水量比HC组要高6.44%。HC组大鼠肝脏组织中胆固醇和甘油三酯要显著高于HL组(P0.05),说明Lp3可以减少脂类物质在肝脏组织中的沉积。从肝脏组织切片来看,也可以得出上述结论。【结论】结果表明本研究所筛选的植物乳杆菌Lp3对高脂大鼠具有值得深入研究的益生作用。