The importance of lactic acid bacteria for phytate degradation during cereal dough fermentation

Lactic acid fermentation of cereal flours resulted in a 100 (rye), 95-100 (wheat), and 39-47% (oat) reduction in phytate content within 24 h. The extent of phytate degradation was shown to be independent from the lactic acid bacteria strain used for fermentation. However, phytate degradation during cereal dough fermentation was positively correlated with endogenous plant phytase activity (rye, 6750 mU g(-1); wheat, 2930 mU g(-1); and oat, 23 mU g(-1)), and heat inactivation of the endogenous cereal phytases prior to lactic acid fermentation resulted in a complete loss of phytate degradation. Phytate degradation was restored after addition of a purified phytase to the liquid dough. Incubation of the cereal flours in buffered solutions resulted in a pH-dependent phytate degradation. The optimum of phytate degradation was shown to be around pH 5.5. Studies on phytase production of 50 lactic acid bacteria strains, previously isolated from sourdoughs, did not result in a significant production of intra- as well as extracellular phytase activity. Therefore, lactic acid bacteria do not participate directly in phytate degradation but provide favorable conditions for the endogenous cereal phytase activity by lowering the pH value.     

主成分分析法优选枸杞乳酸菌发酵饮品发酵剂

乳酸菌发酵作为果蔬汁的一种绿色加工技术,不仅可以赋予产品独特的风味,还可以转化其中的活性物质,提高产品的营养价值和保健功效。该研究以湖北杂交枸杞为原料,使用6种乳酸菌(植物乳杆菌、嗜热链球菌、嗜酸乳杆菌、鼠李糖乳杆菌、干酪乳杆菌及发酵乳杆菌)进行发酵,研究发酵前后枸杞果汁理化特性、主要活性成分及体外抗氧化变化,并利用主成分分析进行综合评价优选出理想的发酵菌株。结果表明,6种乳酸菌在枸杞果汁中生长良好,活菌数均能达到10.0 lg CFU/mL以上。发酵后的枸杞果汁中总糖和还原糖含量显著降低(P0.05),且植物乳杆菌和嗜热链球菌产酸能力更强,发酵后总酸含量达6.74、6.07g/kg。与未发酵枸杞果汁相比,经植物乳杆菌、嗜热链球菌、鼠李糖乳杆菌和发酵乳杆菌发酵的枸杞果汁中总酚含量增加了13.76%～28.07%,而嗜酸乳杆菌和干酪乳杆菌发酵后无显著性差异(P0.05)。6种乳酸菌发酵后枸杞果汁中总黄酮含量增加了55.80%～161.97%。发酵枸杞果汁的抗氧化活性与发酵前相比均有显著提高(P0.05)。基于主成分分析的综合评价函数显示经植物乳杆菌、发酵乳杆菌发酵的枸杞果汁品质更优,适宜作为开发枸杞高值化绿色加工饮品的发酵剂。     

龙眼果浆复合乳酸菌发酵工艺优化

为筛选出适合龙眼发酵的复合乳酸菌,优化建立其发酵工艺,比较分析了7种不同的乳酸菌发酵龙眼的降糖能力和释放结合态酚类物质的能力,发现明串珠菌降糖能力最强,植物乳杆菌释放结合态酚能力最强。利用植物乳杆菌和明串珠菌复合发酵龙眼果肉,以游离酚质量分数和还原糖质量分数结合的综合模糊评判值为指标,通过Box-benhnken中心组合试验设计,确定复合乳酸菌发酵龙眼的最佳工艺条件。结果表明,各因素对复合乳酸菌发酵龙眼果浆的模糊评判值影响程度从强到弱依次为:发酵时间发酵温度接种量料液比。复合乳酸菌发酵龙眼的最佳工艺为:料液比为1∶7(g/m L),发酵温度为37℃,发酵时间为53 h,接种量为1.4%,菌种配比为1∶1。在最佳工艺条件下,发酵龙眼果浆的游离酚质量分数为(161.77±3.93)mg/(100 g),还原糖质量分数为(122.80±3.64)mg/g。该研究为开发低糖含量,且适合糖尿病、肥胖症等病人食用的龙眼乳酸菌发酵饮料新产品提供参考。     

Structural identification of novel oligosaccharides produced by Lactobacillus bulgaricus and Lactobacillus plantarum

β-Galactosidases (β-Gal) of lactic acid bacteria produce oligosaccharides from lactose when suitable acceptor carbohydrates are present. This study aimed to elucidate the structure of oligosaccharides formed by galactosylation of N-acetylglucosamine (GlcNAc) and fucose. Crude cellular extract of Lactobacillus bulgaricus and LacLM of Lactobacillus plantarum were used as sources of β-Gal activity. Disaccharides obtained by galactosylation of GlcNAc were identified as Gal-β-(1→4)-GlcNAc or Gal-β-(1→6)-GlcNAc by liquid chromatography-tandem mass spectrometry (LC-MS/MS) and comparison with external standards. Trisaccharides were identified as Gal-β-(1→6)-Gal-β-(1→[4 or 6])-GlcNAc by LC-MS, analysis of the MS/MS spectra of selected in-source fragment ions, and their relative retention times. LC-MS analysis revealed the presence of five galactosylated fucosides, but their linkage type could not be identified, partly due to the lack of reference compounds. β-Gal of lactic acid bacteria may serve as suitable tools for the chemoenzymatic synthesis of therapeutic oligosaccharides.     

Use of fungal phytase to improve breadmaking performance of whole wheat bread.

The possible use of phytase as a breadmaking improver has been tested in whole wheat breads by adding different amounts of fungal phytase. The effect of phytase addition on the fermentation stage and the final bread quality was analyzed. The phytase addition shortened the fermentation period, without affecting the bread dough pH. Regarding the whole wheat bread, a considerable increase of the specific bread volume, an improvement of the crumb texture, and the width/height ratio of the bread slice were obtained. An in vitro assay revealed that the improving effect of phytase on breadmaking might be associated with the activation of alpha-amylase, due to the release of calcium ions from calcium-phytate complexes promoted by phytase activity. As a conclusion, phytase offers excellent possibilities as a breadmaking improver, with two main advantages: first, the nutritional improvement produced by decreasing phytate content, and second, all the benefits produced by alpha-amylase addition can be obtained by adding phytase, which promotes the activation of endogenous alpha-amylase.     

Antiallergic effect of milk fermented with lactic acid bacteria in a murine animal model

The objective of this study was to assess the antiallergic effect of fermented milk prepared, respectively, with Streptococcus thermophilus MC, Lactobacillus acidophilus B, Lactobacillus bulgaricus Lb, L. bulgaricus 448, and Bifidobacterium longum B6. Female BALB/c mice fed fermented milk were immunized intraperitoneally with ovalbumin (OVA)/complete Freund's adjuvant (CFA) to evaluate the immune response by observing the secretion of cytokines IL-2, IL-4, and IFN-gamma and serum antibody IgE. The results showed that supplementation with lactic acid bacteria fermented milk did not significantly change the IL-2 spontaneous and OVA-stimulated secretions of splenocytes. However, both spontaneous and OVA-stimulated secretions of splenocytes from mice fed lactic acid bacteria fermented milk showed significantly (P < 0.05) lower levels of IL-4 (Th2 cytokine) than those from OVA/CFA-immunized mice fed non-fermented milk (OVA/CFA-milk group). The spontaneous secretion of IFN-gamma (Th1 cytokine) by splenocytes from mice fed L. bulgaricus 448 or L. bulgaricus Lb fermented milk significantly increased as compared to that from the OVA/CFA-milk group. The results showed that the ratios of IFN-gamma to IL-4 of both spontaneous and OVA-stimulated secretions in splenocytes from mice fed lactic acid bacteria fermented milk increased significantly as compared to that of PBS- or OVA/CFA-milk groups. The serum levels of OVA-specific IgE in fermented milk fed groups, especially the group fed S. thermophilus MC fermented milk, were significantly lower than those in the OVA/CFA-milk group through a 6 week feeding experiment. The results showed that milk fermented with lactic acid bacteria demonstrated in vivo antiallergic effects on OVA/CFA-immunized mice via increasing the secretion ratio of IFN-gamma/IL-4 (Th1/Th2) by splenocytes and decreasing the serum level of OVA-specific IgE.     

Changes in Phytate Content in Whole Meal Wheat Dough and Bread Fermented with Phytase‐Active Yeasts

The degradation of inositol hexakisphosphate (IP6) was evaluated in whole meal wheat dough fermented with baker's yeast without phytase activity, different strains of Saccharomyces cerevisiae (L1.12 or L6.06), or Pichia kudriavzevii with extracellular phytase activity to see if the degradation of IP6 in whole meal dough and the corresponding bread could be increased by fermentation with phytase‐active yeasts. The IP6 degradation was measured after the dough was mixed for 19 min, after the completion of fermentation, and in bread after baking. Around 60–70% of the initial value of IP6 in the flour (10.02 mg/g) was reduced in the dough already after mixing, and additionally 10–20% was reduced after fermentation. The highest degradation of IP6 was seen in dough fermented with the phytase‐active yeast strains S. cerevisiae L1.12 and P. kudriavzevii L3.04. Activity of wheat phytase in whole meal wheat dough seems to be the primary source of phytate degradation, and the degradation is considerably higher in this study with a mixing time of 19 min compared with earlier studies. The additional degradation of IP6 by phytase‐active yeasts was not related to their extracellular phytase activities, suggesting that phytases from the yeasts are inhibited differently. Therefore, the highest degradation of IP6 and expected highest mineral bioavailability in whole meal wheat bread can be achieved by use of a phytase‐active yeast strain with less inhibition. The strain S. cerevisiae L1.12 is suitable for this because it was the most effective yeast strain in reducing the amount of IP6 in dough during a short fermentation time.     

Heat-killed cells of lactobacilli skew the immune response toward T helper 1 polarization in mouse splenocytes and dendritic cell-treated T cells

It is believed that probiotics play an important role for the health of the host, including modulation of immune responses. Most studies have focused on the immunomodulatory effects of viable cells of lactic acid bacteria; however, we investigated those of heat-killed cells of lactic acid bacteria in this study. We first observed the effects on immune functions via stimulating splenocytes with three heat-killed Lactobacillus strains. Furthermore, we also investigated the effect of mouse dendritic cells (DCs) treated with these heat-killed Lactobacillus strains on T cell responses. The results showed that these Lactobacillus strains were able to stimulate cell proliferation and interleukin (IL)-10, IL-12 p70, and interferon (IFN)-gamma production but not transforming growth factor (TGF)-beta in splenocytes. In addition, these heat-killed Lactobacillus strains also stimulated high-level secretion of IL-12 p70 in DCs and switched T cells to T helper (Th) 1 immune responses, as evidenced by the elevated secretion of IFN-gamma but not IL-5, IL-13, and TGF-beta. These results showed that lactobacilli play a potentially important role in modulating immune responses and allergic reactions.     

不同乳酸菌发酵甘薯渣产物组分分析

为提高甘薯淀粉加工副产物的高值化利用水平,本试验以植物乳杆菌(Lp)、干酪乳杆菌(Lc)、保加利亚乳杆菌(Lb)、戊糖片球菌(Pp)、嗜热链球菌(St)、商业植物乳杆菌(SZ)6种乳酸菌分别对甘薯渣进行发酵,系统分析不同发酵产物的pH值、总酸含量及营养功能成分,并采用灰色理论加权关联度对甘薯渣发酵产物进行综合营养评价,筛选适宜发酵甘薯渣的乳酸菌菌种。结果表明,6种乳酸菌的发酵能力存在显著差异,其中Lb组pH值最低(3.15),Lc组总酸含量最高(27.90);同时,不同乳酸菌对发酵产物中营养功能成分的影响存在显著差异,其中Lb组乳酸含量最高(11.60 mg·mL^-1),SZ组乙酸含量最高(66.99μg·mL^-1),Lb组可溶性膳食纤维含量最高(0.74 g·100 mL^-1),St组总酚含量最高(146.87μg GAE·mL^-1)。与未发酵样品相比,Lc组游离氨基酸总量提高了3.71倍;所有发酵产物中的Mg、Ca、Fe、Zn、Se等矿物质元素含量均显著提高。进一步通过灰色理论加权关联度分析发现...     

自然发酵和接种发酵方法对白菜品质的影响(简报)

以自然发酵和人工接种发酵(Lactobacillus pentosus 和 Leuconostoc.mesenteroides 为发酵剂)加工的白菜为材料,对比了两种加工白菜亚硝酸盐含量随时间的变化以及有益微生物(乳酸菌)和有害微生物数量的变化,并对其制品做了感观分析.结果得出人工接种发酵白菜中亚硝酸盐含量在发酵整个过程均比自然发酵的低,且未出现自然发酵白菜初期出现的"亚硝峰"; 人工接种发酵白菜中肠杆菌及乳酸菌之外的需氧嗜温菌的数量较自然发酵的少;乳酸菌数量较自然发酵的多;人工接种发酵白菜感官分析优于自然发酵.说明人工接种发酵白菜的品质优于自然发酵加工的制品.     

Wine volatile and amino acid composition after malolactic fermentation: effect of Oenococcus oeni and Lactobacillus plantarum starter cultures

Red wine amino acids and volatile compounds were analyzed before and after malolactic fermentation carried out by four different starter cultures of the species Oenococcus oeni and Lactobacillus plantarum. The purpose of this study was to determine whether differences can be attributed to the lactic acid bacteria strain used in this important step of the wine-making process. The malolactic cultures selected for this study were indigenous wine lactic acid bacteria strains. The data were evaluated using different multivariate analysis techniques. Results showed different malolactic behaviors for O. oeni and L. plantarum and significant metabolic differences between both species. A degree of diversity was found within each lactic acid bacteria group, since wines presented specific characteristics depending on the lactic acid bacteria strain used. In all cases, malolactic fermentation seemed to modify the amino acid and volatile composition of the wine.     

酸乳高自溶度复合发酵剂配方优化

乳酸菌的自溶特性可对发酵乳制品品质产生影响,发酵剂菌体快速自溶不仅缩短酸乳发酵周期、降低了生产成本,同时菌体自溶之后释放的胞内物质又决定着酸乳的风味和感官特性。为了复配出一种高质量的复合型酸乳发酵剂,该文对前期研究筛选出的3株高度自溶的酸乳发酵剂菌株:德氏乳杆菌保加利亚亚种(Lactobacillus delbrueckii ssp.Bulgaricus)LD3-A3、唾液链球菌嗜热亚种(Streptococcus salivarius ssp.)GS1-A8和乳酸乳杆菌(Lactobacillus lactis)S15-A3进行复配,运用二次正交旋转组合设计复合发酵剂中各菌株比例,并讨论了3株菌株之间的共生关系和交互作用,根据所建模型优选结果,最后确定3种菌株最优组合方案为:GS1∶LD3-A3∶S15-A3为45∶1∶3。使用该复合发酵剂制作的酸乳感官性状优良,具有较好的风味和质地,在货架期贮藏条件下(10~15℃)后酸化程度小,可极好的满足生产需要。该文所得高自溶度复合发酵剂具有很好的生产实践指导和应用价值。     

腌制叶用芥菜发酵菌分离鉴定及应用研究

为获得发酵性能优良的菌株,生产优质的发酵叶用芥菜,本研究从自然发酵的芥菜中分离发酵用菌株,通过测定乳酸菌的生长、产酸和亚硝酸盐降解能力以及酵母菌的产气、产酯能力和蛋白酶活性等发酵特性进行筛选,并对筛选获得的优良发酵菌加以应用。结果表明,筛选获得的2株乳酸菌L8短乳杆菌(Lactobacillus brevis)、L9植物乳杆菌(Lactobacillus plantarum)和1株酵母菌Y9酿酒酵母菌(Saccharomyces cerevisiae)在腌制叶用芥菜中的发酵性能优良。与自然发酵的叶用芥菜相比,接菌发酵叶用芥菜的pH值和亚硝酸盐含量分别减少了2.22%和88.13%;总酸含量、氨基酸态氮含量分别增加了9.02%和28.09%。接菌发酵提高了腌制芥菜的营养品质和安全性。本研究丰富了叶用芥菜的发酵菌种,为蔬菜发酵加工产业奠定了技术基础。     

同/异型乳酸菌对青贮玉米开窖后品质及微生物的影响

该研究旨在分析添加不同发酵类型的乳酸菌处理对开窖后玉米（Zea mays L.）青贮发酵品质、微生物数量及有氧稳定性的影响,为生产实践提供参考。设计4个添加乳酸菌玉米青贮处理：CK处理（不加任何菌剂）;T处理（同型发酵乳酸菌）：Lactobacillus plantarum和Pediococcus acidilactici复合添加,添加量为1∶1,1×105 cfu/g;Y处理（异型发酵乳酸菌）：Lactobacillus buchneri,添加量为1×105 cfu/g;TY处理（同型+异型发酵乳酸菌）：Lactobacillus plantarum、Pediococcus acidilactici和Lactobacillus buchneri复合添加,添加量为1∶1∶1,1×105 cfu/g。发酵期为60 d,检测开窖后各处理第0、48、96、144、192、240 h发酵品质及微生物的变化,应用隶属函数法对玉米青贮发酵品质及微生物数量进行综合评判。结果表明Y和TY处理的有氧稳定时间显著高于其余处理（63.87～64.67 h,P<0.05）,分别达到195.58和196.21 h,且乙酸质量分数始终显著高于CK和T处理（P<0.05）。T处理pH值始终显著低于其余处理（P<0.05）,且乳酸质量分数始终显著高于CK和Y处理（P<0.05）。Y处理WSC（water soluble carbohydrate）质量分数始终显著高于其余处理（P<0.05）,霉菌数量始终显著低于其余处理（P<0.05）。CK处理的NH3-N质量分数,好氧细菌数量及CO2产量始终显著高于其余处理（P<0.05）。开窖时间与各处理的CO2产量、乳酸菌和酵母菌数量分别满足Allometric1,ExpDec1和Logistic非线性关系,与霉菌和好氧细菌数量呈一元线性关系。综合评价排序：Y处理>TY处理>T处理>CK处理。因此,单一添加异型发酵乳酸菌的玉米青贮,开窖后在改善发酵品质、降低有害微生物数量、提高有氧稳定性方面均优于单一添加同型或复合添加乳酸菌的玉米青贮。     

产脂肪酶乳酸菌对新疆传统奶酪脂肪酸及风味的影响

为了改善奶酪品质,奶酪生产过程中通常会添加脂肪酶或者产脂肪酶乳酸菌来提升产品品质。该研究以前期筛选的4株高产脂肪酶乳酸菌为发酵剂,分别随机选取3株乳酸菌复配制作酸凝奶酪。试验组：A组T1-5和T1-3属融合魏斯氏菌（Weissella confusa）、H1-6属瑞士乳杆菌（Lactobacillus helveticus）,B组H1-6、T1-5、B2-5属植物乳杆菌（Lactobacillus plantarum）,C组H1-6、T1-3、B2-5,D组T1-3、T1-5、B2-5,对照组（E组）（添加商业发酵剂）,分析发酵剂对传统奶酪pH值、滴定酸度和脂肪氧化情况的影响,并利用气相色谱法（Gas Chromatography,GC）检测奶酪中脂肪酸变化、利用气相色谱-离子迁移谱（Gas Chromatography-Ion Mobility Chromatography,GC-IMS）分析奶酪中风味物质的变化。结果表明：A,B,C,D组4组奶酪的pH值、过氧化值（Peroxide value,POV值）明显低于E组（对照组）（P < 0.05）,A,B组奶酪滴定酸度比对照E组高（P < 0.05）;A,B,C,D组奶酪中饱和脂肪酸（Saturated Fatty Acids,SFA）含量、单不饱和脂肪酸（Monounsaturated Fatty Acids,MUFA）含量和多不饱和脂肪酸（Polyunsaturated Fatty Acids,PUFA）含量均显著高于E组（P < 0.05）;4个试验组样品中亚油酸（C18∶2n6c）含量明显高于对照组（E组）（P < 0.05）。GC-IMS及主成分分析结果显示,A、B组奶酪挥发性风味物质种类多,且相似度较高,其中2-庚酮、丁醛、乙酸丁酯是主要呈味物质;C、E两组奶酪中风味物质比较相似,风味物质主要以乙酸乙酯、乙酸丙酯、己酸乙酯等酯类为主;D组与其他4组有所差异,主要挥发性风味物质为乙酸丁酯、3-辛酮、庚醛等。结合感官评定,A、B两组奶酪整体风味和口感较好,评分较高。筛选得到的产脂肪酶乳酸菌可以作为发酵剂用于提升新疆传统奶酪品质。     

N~+注入诱变高自溶度的乳酸菌突变株

通过N+注入方式对乳酸菌唾液链球菌嗜热亚种GS1和德氏乳杆菌保加利亚亚种LD3进行诱变,获得自溶度较高的乳酸菌菌株。离子注入剂量为1×2.6×103～6×2.6×1013时,菌株的存活率曲线呈典型的"马鞍型"剂量-效应曲线,总突变率达到57%～74%。离子注入能量为50keV,最佳注入剂量为4×2.6×1013 ion/cm2,此时,菌体存活率为25%～33%。筛选得到的乳酸菌菌株,自溶度变化幅度在127.98%～-51.96%之间。得到2株自溶度显著提高的突变菌株,分别命名为LD3-A3和GS1-B13,与出发菌株相比其自溶度分别提高了127.98%和115.11%。经5次传代培养,突变株的自溶度和遗传性状比较稳定。结果表明离子注入诱变技术是一种理想的乳酸菌发酵剂菌种选育方法。     

Effects of Bran Fermentation on Quality and Microstructure of High‐Fiber Wheat Bread

We compared the effects of spontaneous fermentation of the bran fraction and fermentation with added yeast or added yeast and lactic acid bacteria (Lactobacillus brevis) on the quality of wheat bread supplemented with bran. Prefermentation of wheat bran with yeast or with yeast and lactic acid bacteria improved the loaf volume, crumb structure, and shelf life of bread supplemented with bran. The bread also had added flavor and good and homogenous crumb structure. Elasticity of the crumb was excellent. Spontaneous fermentation of the bran fraction did not have the same positive effects on bread quality. The microstructure of the breads was characterized by light microscopy. The positive effect of fermentation of bran on bread quality was evident when comparing the well‐developed protein network structure of the breads baked with fermented bran with the control bread. Prefermentation of the bran with yeast and lactic acid bacteria had the greatest effect on the structure of starch. The starch granules were more swollen and gelatinized in the breads made with prefermented bran. The pretreatments of the bran fraction had no detectable effect on the microstructure of the cell wall particles in the test breads.     

果蔬垃圾重复批次发酵协同制备乳酸和短链脂肪酸

利用果蔬垃圾厌氧合成中链脂肪酸（medium-chain fatty acids,MCFAs）等化学品是厌氧技术高值化的重要方向。中链脂肪酸合成通常需要以乳酸/乙醇（电子供体）和短链脂肪酸（电子受体）为碳源进行碳链延长反应。因此,利用有机废弃物连续、稳定地协同制备乳酸和短链脂肪酸是中链脂肪酸合成的关键步骤。该研究考察了果蔬垃圾重复批次发酵协同制备乳酸和短链脂肪酸（short-chain fatty acids,SCFAs）的可行性,研究了不同置换率和进料浓度对果蔬垃圾重复批次发酵产酸特性的影响。结果表明,调控重复批次发酵的置换率和进料浓度是提高生产率、改善乳酸/SCFAs比例的有效方法。综合考虑酸化产物的生产率、乳酸/SCFAs比例和碳源浓度,在70%置换率和8%进料TS(total solid)浓度条件下获得的酸化产物相对更有利于MCFAs的合成。此时,酸化产物生产率达到（5.25±0.25）g/(L·d),乳酸/SCFAs的碳摩尔比例达到5±0.3,碳源浓度达到（985±29）mmol C/L。微生物群落分析显示,乳酸菌,如Lactobacillus和Enterococcus作为优势菌通过异型乳酸发酵协同制备乳酸和SCFAs。研究结果可为果蔬垃圾的高值化利用提供参考。     

Improved bioavailability of dietary phenolic acids in whole grain barley and oat groat following fermentation with probiotic Lactobacillus acidophilus , Lactobacillus johnsonii , and Lactobacillus reuteri

The aim of this study was to improve the bioavailability of the dietary phenolic acids in flours from whole grain barley and oat groat following fermentation with lactic acid bacteria (LAB) exhibiting high feruloyl esterase activity (FAE). The highest increase of free phenolic acids was observed after fermentation with three probiotic strains, Lactobacillus johnsonii LA1, Lactobacillus reuteri SD2112, and Lactobacillus acidophilus LA-5, with maximum increases from 2.55 to 69.91 μg g(-1) DM and from 4.13 to 109.42 μg g(-1) DM in whole grain barley and oat groat, respectively. Interestingly, higher amounts of bound phenolic acids were detected after both water treatment and LAB fermentation in whole grain barley, indicating higher bioaccessibility, whereas some decrease was detected in oat groat. To conclude, cereal fermentation with specific probiotic strains can lead to significant increase of free phenolic acids, thereby improving their bioavailability.     

蚯蚓粪中乳酸菌的分离及其在大肠杆菌O157：H7中的抗菌活性

本研究利用SL培养基从蚯蚓粪中分离到54株具有产酸性能的菌株,并以E.coli O157：H7（EDL933株）作为指示菌株,采用点种法检测分离菌株的抑菌活性。结果表明其中6个菌株对指示菌具有拮抗作用,通过形态特征,结合16S rDNA序列分析,初步鉴定该6个菌株分别为食物魏斯特菌（Listeria welshimeri）、乳酸片球菌（Pediococcus acidilactici）、短乳杆菌（Lactobacillus brevis）和格氏乳球菌（Lactococcus garvieae）。分离到的乳酸菌对E.coli O157：H7（EDL933株）具有显著的抑制作用,发酵温度和初始pH值影响发酵液的抑菌作用,优化环境因子可以促进拮抗菌对E.coli O157：H7的抑制作用。本研究为进一步分离抗菌产物用于人畜共患病的预防和治疗提供了理论依据。