基于电子鼻和气相-离子迁移谱探究辣椒素对植物乳杆菌LP-CL-01产香特性的影响

本研究以传统发酵糍粑辣椒中分离出的植物乳杆菌LP-CL-01为研究对象,采用气相色谱-离子迁移谱（GC-IMS）结合电子鼻（E-Nose）探究辣椒素胁迫对植物乳杆菌发酵特性的影响。结果表明：E-Nose可以准确区分出辣椒素胁迫及不同发酵时间植物乳杆菌的风味差异。利用GC-IMS技术共检测出48种挥发性物质,在辣椒素胁迫下随着发酵时间的延长,植物乳杆菌LP-CL-01产生乙酸乙酯、2-庚酮和2-甲基丁基乙酸酯等的相对含量显著增加（P<0.05）;N-亚硝基吗啉和左旋香芹酮等的相对含量显著降低（P<0.05）。综上所述,辣椒素胁迫会影响植物乳杆菌产香特性。该研究为植物乳杆菌在辣椒素胁迫条件下代谢产物变化研究提供借鉴,同时为改善传统发酵辣椒制品的风味质量提供参考。     

蔬菜乳酸菌腌渍发酵过程亚硝酸盐变化研究

研究了蔬菜腌渍发酵过程中添加乳酸菌纯培养液对亚硝酸盐含量变化的影响。实验结果表明,接种乳酸菌能降低蔬菜腌渍发酵过程中亚硝酸盐含量。4组乳酸菌腌渍发酵实验中,接种混合菌种(干酪乳杆菌∶鼠李糖乳杆菌∶植物乳杆菌=1∶1∶1)对蔬菜湿腌发酵时菜料和菜汤的亚硝酸盐含量降低效果最佳,接种植物乳杆菌对蔬菜干腌发酵时菜料亚硝酸盐含量降低作用最显著。     

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。     

副干酪乳杆菌NCU622耐酸耐胆盐及其黏附性能

通过体外实验研究副干酪乳杆菌NCU622的耐酸、耐胆盐性能;采用体外细胞模型（人体结肠腺癌细胞系Caco-2细胞）测定副干酪乳杆菌NCU622的黏附性能,考察了菌体浓度、作用时间及生长阶段对其黏附性能的影响,并对该菌株进行细胞毒性检测。结果表明：副干酪乳杆菌NCU622在pH 2.5的MRS液体培养基中作用3 h,存活率为98.21%;在胆盐质量浓度为0.3、0.5 g/100 mL的MRS液体培养基中作用4 h,存活率分别为95.14%和85.07%。副干酪乳杆菌NCU622对Caco-2细胞的黏附能力较强,为（21.19±0.94）CFU/Caco-2细胞,且菌体浓度、作用时间及生长阶段对其黏附性能均有影响。副干酪乳杆菌NCU622与Caco-2单层细胞共培养24 h后,对其无裂解作用。这表明副干酪乳杆菌NCU622具有良好的耐酸耐胆盐能力及较强的黏附性能,且对Caco-2细胞无裂解作用,符合微生态制剂和乳酸菌发酵功能食品的菌种要求。     

酢辣椒中益生乳酸菌的筛选及其功能特性

为从酢辣椒筛选出具有益生特性的菌株,开发辣椒益生菌产品,本实验从地方特色发酵食品酢辣椒中分离得到16 株乳酸菌,以产酸速度、耐人工胃液能力为指标进行初筛,通过生化实验和16S rDNA序列分析方法鉴定;并通过研究菌株对工艺逆境的耐受能力,表面疏水性和自聚合能力以及抑菌活性、抗氧化能力、降解亚硝盐能力和安全特性来评价乳酸菌的益生特性。结果表明：发酵乳杆菌17-1、发酵乳杆菌18-2和短乳杆菌L3-5能耐受0.4%苯酚、溶酶菌和热处理;具有较高的表面疏水性和自聚合能力;能产生具有广谱抑菌效果的细菌素来抑制病原菌的生长;菌株L3-5和17-1具有较高的抗氧化能力;3 株菌都具有胆盐水解酶活性和产γ-氨基丁酸能力,并且都属于安全性菌株。综上所述,传统酢辣椒是分离益生乳酸菌新的天然来源,从中分离得到的发酵乳杆菌17-1、发酵乳杆菌18-2和短乳杆菌L3-5可以作为潜在的益生性菌株。     

1株具有拮抗空肠弯曲杆菌作用的唾液乳杆菌的研究

对分离自泡菜、发酵奶酒以及新鲜婴儿粪便的11株乳酸菌(已证明其发酵上清液对空肠弯曲杆菌生长具有明显抑制作用)进行研究。经对其人工胃、肠液的耐受能力测定,表明这11株乳酸菌通过胃肠道后均能存活。经对全部乳酸菌抑制共培养空肠弯曲杆菌生长能力的测定及其抑菌物质的鉴定,得到对共培养空肠弯曲杆菌生长具有强烈抑制作用的1株唾液乳杆菌ZX5,该菌发酵上清液的抑菌物质很可能为有机酸、过氧化氢及细菌素类物质。测定该株唾液乳杆菌抑制空肠弯曲杆菌黏附及侵袭HT-29细胞的能力,结果表明ZX5可将空肠弯曲杆菌对HT-29细胞的黏附及侵袭率降低38%~55%。其中,以排阻作用最为明显。     

发酵风干肠中乳酸菌的发酵性能

对从自然发酵风干肠中分离的6 株乳酸菌的发酵性能进行评价,主要包括测定菌株的生长曲线、产酸能力、对NaCl及NaNO2的耐受能力,同时通过吲哚实验和抗生素敏感性测定对菌株的安全性进行初步评价。结果表明：6 株乳酸菌生长趋势接近,均在8 h左右进入生长稳定期,pH值在0～8 h下降最快,清酒乳杆菌和发酵乳杆菌的产酸能力更强;所有菌株均可在6 g/100 mL NaCl和0.015 g/100 mL NaNO2条件下生长,植物乳杆菌和弯曲乳杆菌的NaCl耐受能力最优,清酒乳杆菌和发酵乳杆菌则对NaNO2具有最强的耐受能力;吲哚实验中6 株乳酸菌的反应结果均为阴性,对实验所选抗生素无耐药性,说明6 株乳酸菌具有较好的发酵性能和安全性,可作为功能性发酵剂用于发酵肉制品的生产。     

发酵乳杆菌和戊糖乳杆菌降解亚硝酸盐的效果比较研究

亚硝酸盐是潜在的致癌物质,在各类食品中广泛存在,研究食品中亚硝酸盐的降解对保证食品安全有很重要的意义。乳酸菌是具有多种生理功能的益生菌,对亚硝酸盐有一定的降解作用。在不同接种量、不同培养温度、不同起始pH和不同亚硝酸钠起始浓度条件下分别比较了发酵乳杆菌和戊糖乳杆菌对亚硝酸盐的降解效果。研究表明,发酵乳杆菌在接种量≥1%时,48h就有明显的降解效果;戊糖乳杆菌在接种量≥3%时,48 h才有明显的降解效果。pH值在3.5~5的情况下,2株乳酸菌对亚硝酸盐都有较好的降解效果。发酵乳杆菌在37℃环境下对亚硝酸盐降解效果最好;而戊糖乳杆菌则是在32℃时对亚硝酸盐的降解效果最好。2株乳酸菌对亚硝酸盐最适宜的降解初始浓度≤120μg/mL。结果表明,在相同条件下发酵乳杆菌比戊糖乳杆菌对亚硝酸钠的降解效果好。为发酵食品中优良乳酸菌株的筛选提供科学依据。     

传统发酵牦牛乳中2株高产胞外多糖乳酸菌在模拟消化道中耐受力的研究

从传统发酵牦牛发酵乳中分离出的2株高产胞外多糖乳酸菌,为了研究其在模拟消化道中耐受力,对2株乳酸菌(植物乳杆菌、干酪乳杆菌)分别在人工胃液、人工肠液、人工胆汁和高盐4个模拟人工胃肠道消化环境中进行培养,测其耐受力以及对Caco﹣2细胞的黏附能力。结果表明:植物乳杆菌和干酪乳杆菌在人工胃液中作用3 h的存活率随pH值的增大而增加。在pH4.5时,植物乳杆菌的存活率达到53.63%,干酪乳杆菌的存活率达到50.83%;在人工肠液中作用4h,植物乳杆菌的存活率达到了59.58%,干酪乳杆菌的存活率达到了51.42%;在胆盐环境中培养24 h后的植物乳杆菌和干酪乳杆菌活菌数随牛胆盐质量浓度的增加而降低,活菌数均保持在108cfu/m L以上;在高盐环境中培养24 h后的活菌数随盐质量浓度的增加而降低,活菌数均在108 cfu/mL以上;并且2株乳酸菌的黏附能力也很强,植物乳杆菌可以达到16.83%、干酪乳杆菌可以达到14.86%。结论:植物乳杆菌和干酪乳杆菌均能通过胃进入肠道并保持活力,而且能在肠道很好地定植,为植物乳杆菌和干酪乳杆菌作为益生菌应用在食品中提供了理论基础。     

抑制辣椒采后疫霉菌的乳酸菌筛选及相关特性分析

辣椒疫霉病对辣椒采后经济效益造成了较大损失,但目前暂未见关于采后辣椒疫霉病的生物防治研究。该试验从自然发酵蔬菜中分离筛选出一株对辣椒疫霉菌具有抑制效果的乳酸菌O2,其对辣椒疫霉菌的菌落生长抑制率为87.18%,经16S rDNA和生理生化实验鉴定其为植物乳杆菌（Lactobacillus plantarum）。采用固体稀释法分析O2发酵上清液的理化特性、对辣椒疫霉菌的最小抑菌浓度（MIC）和最小杀菌浓度（MBC）,采用固体稀释法和牛津杯法分别测定O2发酵上清液对辣椒采后致病菌和部分食源性致病菌的抑菌图谱。结果表明,O2发酵上清液对过氧化氢酶、蛋白酶K、胰蛋白酶、胃蛋白酶不敏感,在温度40~120 ℃和15 W紫外灯照射30~150 min、pH值5范围内抑菌物质稳定,对辣椒疫霉菌的MIC和MBC分别为12.8 mg/mL和25.6 mg/mL,对红色炭疽菌、大肠杆菌、沙门氏菌、志贺氏菌和阪崎肠杆菌具有显著抑制效果。综上所述,植物乳杆菌O2具有良好的抑制辣椒疫霉菌效果,其代谢产物稳定性好,可作为采后辣椒疫霉病的生物防治菌株进一步开发利用。     

酵母培养物对3种肠道有益菌体外增殖的影响

该文研究了酵母培养物对双歧杆菌、嗜酸乳杆菌和植物乳杆菌体外增殖的影响。结果显示由发酵培养基制备的酵母培养物具有较好地促进肠道有益菌体外增殖的效果,且添加1%酵母培养物能极显著促进嗜酸乳杆菌和植物乳杆菌体外增殖,但对双歧杆菌的影响不显著;添加5%或10%酵母培养物均能极显著促进3种肠道有益菌体外增殖。通过有益菌生长动力学曲线可以看出添加酵母培养物可以缩短延滞期,延长对数期,且生物量有大幅度提高。     

Identification and biochemical characteristics of yeast microflora of Rokpol cheese

The inhibiting characteristics of lactic acid bacteria on Shiga toxin-producing Escherichia coli (STEC) O157:H7 (three strains, clinically isolated) was investigated by using a batch fermentation system. The species such as Lactobacillus casei strain Shirota or L. acidophilus YIT 0070 exert growth inhibitory and bactericidal activities on STEC. The pH value and undissociated lactic acid (U-LA) concentration of the culture medium of STEC cocultured with L. casei or L. acidophilus dramatically lowered or increased, respectively [corrected], when compared with those of the control culture. The cytotoxic properties of U-LA on STEC strain 89020087 analyzed in vitro was divided into two phases, i.e., the bacteriostatic phase (between 3.2 to 62 mM) and the bactericidal phase (over 62 mM). These data suggest that the bactericidal effect of Lactobacillus on STEC depends on its lactic acid production and pH reductive effect.     

乳铁蛋白及乳铁素对嗜酸乳杆菌生长影响的研究

本实验主要针对乳铁蛋白和乳铁素对嗜酸乳杆菌的生长影响进行研究。结果表明,在37℃恒温培养下,添加一定浓度的乳铁蛋白或乳铁素,可促进嗜酸乳杆菌生长繁殖。乳铁蛋白的最适添加浓度为2.5mg/ml,乳铁素的最适添加浓度为0.15mg/ml,培养26h后活菌数分别达到6.7×108CFU/ml和8.0×108CFU/ml。     

乳酸菌对金黄色葡萄球菌生物拮抗作用的初步研究

利用试管混合培养特性实验发现,保加利亚乳杆菌、嗜热 链球菌和金黄色葡萄球菌共同生长时,保加利亚乳杆菌、 嗜热链球菌二者对金黄色葡萄球菌的生长具有明显的抑 制作用,在混合培养的前12h,实验组金黄色葡萄球菌的 活菌数比对照组下降2-3个对数级,到培养后期则没有 活的金黄色葡萄球菌检出。为了进一步探讨乳酸菌对金 黄色葡萄球菌抑制作用的机理,采用牛津杯法观察了保 加利亚乳杆菌、嗜热链球菌发酵液对金黄色葡萄球菌的 抑制作用,发现其抑制作用主要是由于有机酸和抗菌类 物质共同作用的结果。     

The influence of manufacturing and drying conditions on the survival and toxinogenesis of Staphylococcus aureus in two Spanish dry sausages (chorizo and salchichón)

The effects of formulation, starter culture and fermentation temperature on growth and synthesis of toxin A (SEA) and TNase by Staphylococcus aureus during fermentation and drying of Spanish chorizo were investigated. Inhibitory factors able to inhibit SEA synthesis in culture media were unable to prevent SEA production in chorizo fermented at 20 and 30°C, though a lower temperature and starter culture SP318 (Lactobacillus sake, Pediococcus pentosaceous and Staphylococcus xylosus) decreased staphylococcal growth and SEA formation. Reduction and even disappearance of the SEA during ripening was observed. In most batches, TNase was a reliable indicator of staphylococcal growth and SEA production. Dextrose added to the salchichón formulation repressed S. aureus growth during drying. Lactobacillus curvatus in combination with dextrose was an effective anti-staphylococcal agent during fermentation.     

植物乳杆菌KLDS 1.0318产酸、耐酸、耐胆盐能力及其免疫特性研究

目的:通过体外实验,研究植物乳杆菌KLDS 1.0318的生长曲线、产酸能力、耐酸耐胆盐性能,在此基础上对其可能的免疫调节活性进行研究。方法:采用平板计数法和紫外-可见分光光度法测定菌株生长曲线,pH计测定其产酸能力,平板计数法测定该菌株在酸性及高胆盐环境作用后的活菌数及存活率。采用CCK-8法观察不同剂量的植物乳杆菌KLDS 1.0318对小鼠脾淋巴细胞增殖能力以及对小鼠腹腔巨噬细胞能量代谢水平的影响,采用巨噬细胞吞噬中性红法评估不同剂量的植物乳杆菌KLDS 1.0318对巨噬细胞吞噬作用的影响。结果:植物乳杆菌KLDS 1.0318在4 h后进入对数期,12 h后达到稳定期。其产酸能力较强,pH在12 h后降至4.16。菌株在pH为2.5、3.5条件下培养至3 h时,其存活率分别为91.20%、97.50%,在胆盐质量浓度分别为0.3、0.5 g/100 mL的培养基中作用4 h后,其存活率分别为95.40%、87.76%。一定剂量的植物乳杆菌KLDS 1.0318能够促进脾淋巴细胞和巨噬细胞活性,并呈现剂量依赖关系。结论:植物乳杆菌KLDS 1.0318生长较快,具有较强的产酸、耐酸、耐胆盐能力,并具有潜在免疫调节功能。     

Amino acid profiles of lactic acid bacteria, isolated from kefir grains and kefir starter made from them

The characteristics of cell growth, lactic acid production, amino acid release and consumption by single-strain cultures of lactic acid bacteria (isolated from kefir grains), and by a multiple-strain kefir starter prepared from them, were studied. The change in the levels of free amino acids was followed throughout the kefir process: single-strain kefir bacteria and the kefir starter (Lactococcus lactis C15-1%+Lactobacillus helveticus MP12-3%+(Streptococcus thermophilus T15+Lactobacillus bulgaricus HP1 = 1:1)-3%) were cultivated in pasteurized (92 degrees C for 20 min) cow's milk (3% fat content) at 28 degrees C for 5 h (the kefir starter reached pH 4.7) and subsequently grown at 20 degrees C for 16 h; storage was at 4 degrees C for 168 h. The strain L. helveticus MP12 was unrivaled with respect to free amino acid production (53.38 mg (100 g)(-1)) and cell growth (17.8 x 10(8) CFU ml(-1)); however, it manifested the lowest acidification activity. L. bulgaricus HP1 released approximately 3.7 times less amino acids, nearly 5 times lower cell growth, and produced about 1.2 times more lactic acid. S. thermophilus T15 demonstrated dramatically complex amino acid necessities for growth and metabolism. With L. lactis C15, the highest levels of growth and lactic acid synthesis were recorded (18.3 x 10(8) CFU ml(-1) and 7.8 g l(-1) lactic acid at the 21st hour), and as for free amino acid production, it approximated L. bulgaricus HP1 (17.03 mg (100 g)(-1) maximum concentration). In the L. lactis C15 culture, the amino acids were used more actively throughout the first exponential growth phase (by the 10th hour) than during the second growth phase. The unique properties of the L. helveticus MP12 strain to produce amino acids were employed to create a symbiotic bioconsortium kefir culture, which, under conditions of kefir formation, enhanced lactic acid production and shortened the time required to reach pH 4.7; intensified cell growth activity, resulting in a respective 90- and 60-fold increase in the concentration of lactobacilli and cocci in the mixed culture compared to individual cultures; and accumulated free amino acids in the final kefir with higher total concentrations (56.88 mg (100 g)(-1)) and an individual concentration of essential amino acids (1.5 times) greater than that of yogurt.     

耐酸耐胆盐乳酸菌的鉴定及筛选

从自然发酵的酸奶中分离出2 株细菌,经16S rDNA分子鉴定为Lactobacillus plantarum SN1和Lactobacillusrhamnosus SN6,并对其生长曲线、产酸速率、耐酸耐胆盐能力进行了研究。L. plantarum SN1和L. rhamnosus SN6在2 h后进入对数期,16 h后达到稳定期,其OD600 nm值分别为8.47、7.43。L. plantarum SN1和L. rhamnosus SN6的产酸速率较快,pH值在8 h后就降到了4.2以下,48 h后降到3.3左右。L. plantarum SN1和L. rhamnosus SN6在pH 4的培养基培养16 h后,其相对OD600 nm值分别为49.29%、47.14%,具有较强的耐酸能力。L. plantarum SN1和L. rhamnosus SN6在0.3 g/L胆盐质量浓度下培养16 h后,相对OD600 nm值分别为57.7%、69.48%;在0.6 g/L胆盐质量浓度下的相对OD600 nm值分别为48.22%、29.56%,具有较强的耐胆盐能力。结果表明：L. plantarum SN1和L. rhamnosus SN6是生长性能好、产酸能力强、耐酸耐胆盐的益生菌株。     

Autolysis of Lactobacillus sanfranciscensis

 Autolysis of Lactobacillus sanfranciscensis in phosphate buffer was strain-dependent and maximal in the exponential growth phase and at pH 5.6. It decreased to 15% of the maximum at pH 4.5. In culture medium, autolysis did not correspond to the cell death rate because the low pH reached after fermentation limited it markedly. Appreciable autolysis was only found when buffering citrate or fumarate were added to the culture medium. Leakage of peptidases from cells to the culture medium confirmed the autolysis. Renaturating SDS-PAGE showed an autolytic profile composed of four clean lytic bands of ca. 102, 87, 76.5 and 61.5 kDa. This profile was observed in all strains and did not vary with the growth phase or with the use of the crude cell-envelope or crude extracts. Sourdough fermentations lasting 24–48 h showed no differences in the leakage of peptidases when strains which differed greatly for autolysis were compared. However, if citrate was added to the dough it enhanced the release of intracellular peptidases by fast autolytic strains because of the less acidic conditions which favored microbial autolysis during sourdough fermentation. Received: 5 February 1999