植物乳杆菌LB-B1产细菌素发酵条件的优化

为提高分离自新疆传统发酵乳制品酸马奶中植物乳杆菌LB-B1产细菌素的能力,对其产细菌素的发酵条件进行了优化,分别研究了培养条件(时间、温度、培养基初始pH值)和培养基成分对细菌素产量的影响。通过单因素试验和正交试验,确定产植物乳杆菌LB-B1的最佳培养条件为37℃静置培养20h,培养基初始pH值为6~7;最佳培养基成分组合为葡萄糖30g/L、胰蛋白胨10g/L、牛肉膏10g/L、酵母粉5g/L、无水乙酸钠5g/L、柠檬酸铵2g/L、磷酸氢二钾2g/L、硫酸镁0.28g/L、硫酸锰0.25g/L、吐温-80 4mL/L。在优化发酵条件下,植物乳杆菌LB-B1产细菌素高达10240AU/mL,提高了3倍。     

植物乳杆菌C8-1产细菌素发酵条件优化研究

以XMRS为基础培养基对植物乳杆菌C8-1产细菌素的培养基组成和发酵条件进行了优化,结果表明:最佳碳源为蔗糖,最佳氮源为大豆蛋白胨.刺激因子Tween 80最佳添加量为3‰(体积分数).在大豆蛋白胨1.5%,牛肉膏1.5%,蔗糖2.0%(均为质量分数),初始pH值为6.5,30℃培养28 h条件下培养植物乳杆菌C8-1所产细菌素的效价可达到271.36 IU/mL,增长34.3%,优化后产细菌素能力提高,效果显著.     

瑞士乳杆菌AJT产细菌素的发酵条件优化

瑞士乳杆菌AJT是一株广谱抗菌活性菌株,对革兰氏阳性、革兰氏阴性细菌和真菌均有较好的抑制作用。通过优化试验确定其最优的培养基成分为:乳糖15.0 g/L、酵母浸出粉7.0 g/L、胰蛋白胨6.0 g/L、牛肉浸膏12.0 g/L、乙酸钠7.0g/L、柠檬酸钠7.0 g/L、磷酸氢二钾2.0 g/L、硫酸镁200 mg/L、硫酸锰40 mg/L,吐温-80 1.0 g/L,起始pH6.5;最佳培养条件:接种量2.0%,37℃培养20 h。与未优化发酵条件相比,粗提取的瑞士乳杆菌AJT细菌素对蜡状芽孢杆菌的抗菌活性提高了53.8%,对黄色镰孢的抗菌活性提高了41.5%,对大肠杆菌的抗菌活性提高了68%。     

植物乳杆菌代谢产细菌素的培养基优化

本文对植物乳杆菌代谢产细菌素的培养基进行一系列优化。结果显示,不同培养基对菌株生长和细菌素产量有重要的影响,其中以碳源的影响最为显著。综合考虑,5%糖蜜、0.5%酵母膏、2%胰蛋白胨、0.4%KH2PO4、0.1%MgSO4.7H2O、0.5%CaCO3、0.05%MnSO4和0.3%吐温80是植物乳杆菌生长和代谢产细菌素的最优培养基组合。     

植物乳杆菌M1-NTG300产细菌素培养条件优化

以植物乳杆菌素的效价作为特征性考察指标,对植物乳杆菌M1-NTG300产细菌素培养条件进行优化。通过响应面分析结合实际值确定培养基最佳组分为:葡萄糖浓度3.5%、蛋白胨浓度3.5%、吐温80浓度0.35%、氯化镁浓度0.20%,此培养条件下植物乳杆菌M1-NTG300所产细菌素的效价为1 269.4IU/mL,细菌素效价提高了19.8%。     

响应曲面法优化乳杆菌产细菌素的条件研究

以分离自泡菜可产细菌素的乳杆菌作为实验菌,优化其产细菌素的最佳培养条件,以提高其产细菌素的能力。通过Plackett-Burman实验筛选出对乳杆菌产细菌素有显著影响的3个因素,分别为装液量、葡萄糖质量浓度以及蛋白胨质量浓度。以抑菌圈直径大小作为产细菌素能力大小的判断依据,通过最陡爬坡实验和Box-Behnken实验进一步优化,并对优化的结果进行验证,验证结果表明,预测值和实际值有良好的拟合性,此优化模型可靠。最后确定的乳杆菌产细菌素的优化培养基组成为:蛋白胨30g/L、葡萄糖15g/L、柠檬酸氢二铵2g/L、K2HPO42g/L、乙酸钠5g/L、MnSO4.4H2O0.25g/L、MgSO4.7H2O0.58g/L、吐温800.1%;最佳培养条件为:装液量25mL、温度30℃、培养时间24h、接种量1%、pH6.0。在此优化发酵条件下,细菌素的产量提高了30%。      

产细菌素戊糖乳杆菌B8发酵动力学模型的建立

从四川香肠中选育出一株具有产细菌素能力的戊糖乳杆菌B8,在10 L发酵罐内对其进行分批发酵动力学研究,建立菌体生长、产物合成、底物消耗及pH随时间变化的动力学模型,确定模型参数,得到其菌体生长动力学模型■ =0.56691-■、细菌素生产动力学模型■=75.25■ +122.94X、葡萄糖消耗动力学模型-■=5.843■+0.799 8X。pH值变化的数学模型y =■+5.992 8。结果表明,模型预测值与实验值吻合较好,为工业放大生产细菌素提供了理论依据和方法。     

棉籽糖乳球菌Y-12产细菌素培养条件优化

目的:以分离自独山盐酸菜产细菌素棉籽糖乳球菌Y-12为研究对象,对其产细菌素培养条件进行优化。方法:利用单因素和Plackett-Burman实验确定发酵温度、发酵时间、初始p H和葡萄糖浓度等发酵条件水平值,在单因素和Plackett-Burman实验的基础上,采用Box-Behnken法设计三因素三水平实验进行响应面优化,确定菌株Y-12产细菌素最佳发酵条件。结果:菌株Y-12产细菌素最佳发酵条件为:发酵温度35℃、发酵时间36 h、接种量2%、蛋白胨10.62 g/L、葡萄糖31.61 g/L,初始p H6.46,其他成分（同MRS培养基）保持不变。在此条件下,细菌素抑菌圈直径达16.87 mm,比优化前（14.12 mm）提高19.5%。结论:在最优条件下获得实验结果与模型预测值吻合,说明所建立回归方程模型切实可行。      

植物乳杆菌CGMCC.5297产细菌素条件的优化及应用

用响应面法对植物乳杆菌CGMCC.5297生产细菌素的培养基进行了优化。通过Plackett-Burman设计和中心组合试验设计,植物乳杆菌CGMCC.5297代谢产细菌素的最佳培养条件为酵母粉5.09g/L,牛肉膏10.85g/L,葡萄糖55.34g/L。此时的细菌素上清与指示菌单核细胞增多性李斯特菌CVCC1595共培养4h后,指示菌OD600nm为0.001 73,效价为4499 IU/mL,提高了1.4倍。在最优发酵条件下获得的试验结果与模型预测值吻合,说明所建立的模型是切实可行的。将优化后的植物乳杆菌上清加入到自制酸奶中,发现此细菌素对酸奶具有良好的保鲜效果。     

植物乳杆菌(Lactobacillus plantarum)8-6产细菌素发酵条件的优化

对植物乳杆菌(Lactobacillus plantarum)8-6产细菌素的发酵条件进行了优化,分别研究了培养时间、温度、接种量、培养基起始pH值、培养基碳源、氮源等因素对细菌素产生的影响,通过单因素水平试验和正交试验,确定产细菌素的最佳培养基组合和最佳发酵条件为葡萄糖3%,胰蛋白胨2%,蛋白胨1%,酵母膏1%,硫酸镁0.058%,吐温-80 0.2%,30℃培养24h,培养基起始pH值为6.5,接种量2%。乳杆菌8-6优化后效价为1825.56IU/mL,比优化前提高了373.15%。     

戊糖乳杆菌素pentocin LPEM818的初步纯化及特性研究

对戊糖乳杆菌(Lactobacillus pentosus)LPEM818所产戊糖乳杆菌素(pentocin)LPEM818进行了初步纯化,并对其生物学特性进行了研究。结果表明,采用80%硫酸铵沉淀和Sephadex G-25凝胶层析分离纯化后,细菌素的纯化倍数为11.09倍,回收率为6.4%;该细菌素在pH 2.0～8.0条件下稳定,121℃加热15 min保留84.52%的抑菌活性;对胰蛋白酶和蛋白酶K敏感;该细菌素的作用方式为杀菌;对供试的部分革兰氏阳性菌(G+)和革兰氏阴性菌(G-)具有较强抑制作用,因其抑菌谱较广,对多数致病菌和食品腐败菌有较好抑菌作用,所以具有作为食品生物防腐剂的潜在应用价值。     

戊糖乳杆菌S1-4所产抑菌物质的生物学特性研究

以内蒙古东部地区酸菜中分离得到的具有产抑菌活性的戊糖乳杆菌S1-4为供试菌,以大肠杆菌（Escherichia coli）3301为指示菌,采用双层琼脂扩散法对其所产抑菌物质的生物学特性进行研究。结果表明,戊糖乳杆菌S1-4所产的抑菌物经木瓜蛋白酶处理后,其抑菌活性明显降低,但对胃蛋白酶和胰蛋白酶不敏感。该抑菌物质经热处理后,对大肠杆菌仍保持较强的抑菌活性,在p H3.5⁵.5条件下,其抑菌活性较稳定。该菌株的发酵上清液分别经部分化学试剂和紫外线照射处理后,仍保持较好的抑菌活性。      

植物乳杆菌B_(28)产细菌素的发酵条件研究

从来自保加利亚传统燕麦饮料中分离得到的植物乳杆菌B28出发,以腊样芽胞杆菌Baeillus cereus为指示菌,研究了植物乳杆菌B28生长特性以及产生细菌素的最佳时期;不同氮源、碳源和磷酸盐对细菌素抑菌活性性影响以及不同浓度硫酸铵溶液对细菌素的盐析效果。结果表明,植物乳杆菌B28在37℃条件下培养,14~16 h,生长进入稳定期;产生细菌素最佳发酵时间为24 h;70%的硫酸酸铵是适植物乳杆菌细菌素的盐析质量分数为。与对照培养基对比,植物乳杆菌B28的生长情况是酵母提取物>大豆蛋白>胰蛋白胨、蛋白胨、肉膏;乳糖>D-果糖、蔗糖、D-麦芽糖>D-木糖;磷酸盐对植物乳杆菌B28的生长影响不大。并得到了产生细菌素的最佳培养基配方。     

戊糖乳杆菌S1-4产抑菌物质发酵条件的优化及其抑菌谱

通过单因素及正交试验对戊糖乳杆菌S1-4产抑菌物质的发酵条件进行了优化,并其对敏感菌株的抑菌效果进行了探讨。结果表明,戊糖乳杆菌S1-4产抑菌物质的最佳培养条件为：接种量2.0%,培养基初始pH 5.5,32 ℃培养26 h,其抑菌圈平均直径可达（30.08±0.69） mm,优化前其抑菌圈平均直径为（24.41±0.25）mm,优化后抑菌活性提高了0.23 倍。菌株S1-4所产抑菌物质对所试12 种G＋和G－致病菌的生长都起到抑制作用,呈现出较广谱的抑菌特性。因此,菌株S1-4具有可作为食品生物防腐剂的潜在应用价值。     

Physicochemical Properties,Fatty Acid Profiles,and Sensory Characteristics of Fermented Beef Sausage by Probiotics Lactobacillus plantarum IIA‐2C12 or Lactobacillus acidophilus IIA‐2B4

Probiotics may be used to enhance the functionality and nutritional values of fermented sausages. This study aims to evaluate the physicochemical and sensory properties of beef sausages fermented by lactic acid bacteria of Lactobacillus plantarum IIA‐2C12 and L. acidophilus IIA‐2B4. These strains were isolated from beef cattle and have shown to display probiotic features. While the nutrient contents were not affected by the probiotics, the pH, texture, and color varied among the sausages. Further analysis on fatty acids showed different profiles of saturated (C14:0, C17:0, and C20:0) and unsaturated (C14:1, C18:1n9c, C18:2n6c, and C22:6n3) fatty acids in sausages with probiotics. Gas chromatography–mass spectrometry further revealed some flavor development compounds including acid, alcohols, aldehydes, aromatic, ketones, sulfur, hydrocarbons and terpenes, varied among the sausages. Hedonic test showed no difference in the preference toward aroma, texture, and color for untrained panelists.     

Technological characterization of a bacteriocin-producing Lactobacillus sakei and its use in fermented sausages production

The aim of this paper was the technological characterization of a Lactobacillus sakei strain, able to produce the bacteriocin sakacin P, that was originally isolated from naturally fermented sausages. Experiments were conducted in situ, using MRS-based medium, and in situ, when the strain was inoculated as starter culture in real sausage fermentation. The results obtained underlined that the strain was able to grow in conditions that are commonly used in the production line, and only lactose and high concentrations of NaCl (5% w/v) reduced the capability for bacteriocin production. When inoculated in sausages, the strain showed a good performance, being able to colonize rapidly the ecosystem. A high number of isolates, capable of producing sakacin P, were already isolated after the third day of fermentation, and persisted throughout the course of the fermentation. The inoculated strain also affected other microbial colonization trends; in fact the total bacterial count and fecal enterococci showed a rapid decrease at the end of the fermentation. Moreover, during sensory evaluation, the final sausage product received high scores for the parameters of tenderness and juiciness, with medium acidity and low rancidity. Lastly, the panelists preferred the sausages produced with the L. sakei characterized in this study when compared to a fermented sausage produced with a commercial starter.     

Effect of inulin on growth and bacteriocin production by Lactobacillus plantarum in stationary and shaken cultures

The prebiotic effect of inulin added to MRS medium on growth and bacteriocin production by L. plantarum ST16 Pa was investigated in stationary cultures in anaerobic jars with medium containing 0.025% sodium thioglycolate or in flasks shaken at 100 rpm. In the presence of 1% inulin in anaerobic stationary cultures, this strain produced lactic acid at a level that was 36.5% higher than in the absence of the polysaccharide. In shaken cultures without inulin, cell count was 54% higher than in the stationary ones. Under stationary conditions in anaerobic jars, the addition of inulin increased the maximum specific growth rate from 0.37 to 0.49 h^?1 and reduced the generation time from 1.85 h to 1.40 h. Consequently, the exponential phase was shortened from 12 to 9 h when the cells were grown in stationary cultures with the oxygen scavenger. Despite this effect of inulin on growth rate, stationary cultures without inulin displayed higher antimicrobial activity against Listeria monocytogenes L104 (3200 AU/mL) than cultures with inulin (1600 AU/mL); therefore, inulin behaved as a compound able to accelerate growth rather than to stimulate bacteriocin production. The results presented in this study are very promising, as L. monocytogenes is a well‐known foodborne pathogenic microorganism. Moreover, L. plantarum ST16 Pa has proven to be a potential producer of a natural food preservative at an industrial level.     

植物乳杆菌C8-1产类细菌素的初步研究

从发酵2周的泡菜中分离到66株乳杆菌,以其中4株乳杆菌作为出发菌株进行紫外诱变处理得到一株产类细菌素的突变株C8-1。基于细胞形态、生理生化和16S rDNA测序数据,菌株C8-1被鉴定为植物乳杆菌(Lactobacillus plantarum)。菌株C8-1所产的类细菌素具有较宽的抑菌谱,能够抑制大肠杆菌和金黄色葡萄球菌等多种食品腐败菌和致病菌;有较好的热稳定性,在4℃冷藏5 d和-20℃冷冻5d以及60,80,100℃和121℃分别加热15 min,活性损失均不超过6%;且抑菌活性随pH值增大逐步降低,当pH≥6时,抑菌活性消失,对胃蛋白酶、木瓜蛋白酶耐受性较强,对胰蛋白酶较为敏感。这些数据表明,产类细菌素的植物乳杆菌C8-1在食品加工中具有进一步地潜在应用价值。     

干酪乳杆菌对数生长期与稳定期蛋白质组比较分析

研究建立干酪乳杆菌Lactobacillus casei XM2-1的蛋白质组双向电泳表达图谱,比较其在对数生长中期与稳定期初期的图谱差异。结果表明：有16个蛋白质点表达发生明显变化,经过基质辅助激光解吸/电离飞行时间质谱鉴定,其中有7个蛋白质点鉴定为应激蛋白质,分别为GroEL、DnaK、Hsp 20-1、Hsp 20-2和UspA蛋白质。可见,应激蛋白质可能在L.casei XM2-1稳定期对外界环境的抵御能力增强起到重要作用。