乳酸菌对黄曲霉毒素B1吸附作用的研究

为研究生物防霉去毒，探讨了乳酸菌吸附黄曲霉毒素B1的强度及被吸附的黄曲霉毒素B1的致突变性。将乳酸菌细胞与黄曲霉毒B1在生理盐水中相混合，在37℃振荡培养60min和120min后检测生理盐水中黄曲霉毒素B1的含量，同时利用Ames试验检测被吸附的黄曲霉毒素B1的致突变性。结果表明，在使用的8株乳酸菌中，乳酸菌结合黄曲霉毒素B1的强度在4％—50％之间，其中干酪乳杆菌干酪亚种CCMCCl．539吸附黄曲霉毒素B，能力最强。Ames试验表明，被结合的黄曲霉毒素B1仍有较强的致突变性。     

黄曲霉毒素B1的生物脱毒研究进展

简要介绍了黄曲霉毒素的分子结构、理化性质、对人体健康的危害及黄曲霉毒素B1在食品中的限量标准。重点阐述了近几年黄曲霉毒素B1生物脱毒方面的进展,其中微生物主要通过吸附和降解两方面去除黄曲霉毒素B1。     

乳酸菌对真菌毒素的吸附效果研究

本文探讨了乳酸菌吸附黄曲霉毒素B1的强度及被吸附的黄曲霉毒素B1的致突变性。将乳酸菌细胞与黄曲霉毒素B1在生理盐水中相混合,在37℃振荡培养60min和120min后检测生理盐水中黄曲霉毒素B1的含量,同时利用Ames试验检测被吸附的黄曲霉毒素B1的致突变性。结果表明。在使用的8株乳酸菌中,乳酸菌结合黄曲霉毒素B1的强度在4%-50％之间,其中干酪乳杆菌干酪亚种CGMCC1.539吸附黄曲霉毒素B1能力最强。Ames试验表明,被结合的黄曲霉毒素B1仍有较强的致突变性。     

黑曲霉菌降解黄曲霉毒素B_1的影响因素的研究

谷物类原料因保管不善造成或加工过程中操作不当易产生大量黄曲霉毒素B_1。目前,微生物法已成为降解黄曲霉毒素B1的研究热点。本研究用已筛选出具有降解黄曲霉毒素B1能力的黑曲霉菌为研究对象,从发酵液不同处理方式,热稳定性,p H稳定性,金属离子稳定性等方面,对其降解的影响因素进行了研究。通过对其发酵液不同处理途径和不同条件对其降解黄曲霉毒素B_1能力的影响的研究,初步判断筛选菌株是通过直接代谢和分泌胞外酶两种途径共同降解黄曲霉毒素B_1的,而分泌胞外酶又是其主要的降解黄曲霉毒素B1的手段,因此易受温度、p H、和金属离子的影响。     

生物技术对黄曲霉毒素B1的脱除及机制研究进展

黄曲霉毒素是危害最大的真菌毒素之一,而黄曲霉毒素B₁(AFB₁)是黄曲霉毒素中毒性最大的一种,具有高毒性、致癌、致畸和致突变的作用,对动物和人类健康造成危害。为了有效脱除AFB₁,综述了近年来研究的具有解毒作用的微生物,介绍了采用生物技术脱除AFB₁的方法,重点探讨了生物脱除AFB₁机制。用于脱除AFB₁的菌株有芽孢杆菌、假单胞菌、乳酸菌、非产毒曲霉等,可采用单菌种发酵、多菌种协同发酵和菌-酶协同作用脱除AFB₁。生物脱除AFB₁机制主要为降解脱除和吸附脱除。可进一步筛选具有高优良能力的菌株以及更深层次地研究微生物脱毒的机制,探索微生物制剂对AFB₁的降解作用。     

红茶菌中优势微生物发酵儿茶素的变化研究

以10%蔗糖、0.7%绿茶为主要原料制成的糖茶水为培养基质,传统的红茶菌菌膜分离得到的优势微生物裂殖酵母菌、产膜醋酸菌、乳酸菌A、乳酸菌P为试验菌种,在28℃恒温静止进行单一和混合培养12d,每4d取样分析。结果表明:不同菌种单一和混合培养不同时间,其培养液中的各儿茶素及总量存在明显差异,产膜醋酸菌混合培养有促进EGCG、ECG降解的作用。酵母菌、醋酸菌和乳酸菌A、P混合培养,其培养液中酯型儿茶素含量远远高于酵母菌、醋酸菌混合培养液,乳酸菌A、P有抑制酯型儿茶素降解的作用。     

降解黄曲霉毒素微生物筛选中降解与吸附结合作用的区分

黄曲霉毒素的污染不仅带来巨大的经济损失,而且严重危害人和动物的健康,因而生物降解真菌毒素一直引人关注。但在研究黄曲霉毒素微生物降解时,首先必须要有可靠的方法来判定毒素是被降解还是可逆的吸附结合。该文在黄曲霉毒素B1(AFB1)降解菌株筛选中,对区分降解与吸附结合作用的方法进行了研究,建立了可靠的分析方法,通过比较不同pH的影响,细胞灭活对AFB1去除的影响,分析菌株细胞水洗脱、有机溶剂萃取后AFB1的变化等方法,有效地排除了生物吸附结合以及pH的干扰,区分了降解作用和可逆的吸附作用,这些方法简单实用。据此,从动物粪便中成功筛选到了2株能高效降解AFB1的菌株F4、F7。     

农产品中真菌毒素的微生物脱除研究进展

农产品中的真菌毒素污染,不仅造成农业产业的巨大经济损失,而且直接危害人类的身体健康。虽然物理法与化学法在早期真菌毒素脱除中发挥了一定的作用,但是通过微生物脱除真菌毒素,作为一种安全、高效、经济的方式越来越受到认可。本文综述微生物对农产品中常见真菌毒素的两种主要脱除方式（吸附和降解）,前者主要包括乳酸菌及酵母,以菌体吸附的方式,对黄曲霉毒素、玉米赤霉烯酮、脱氧雪腐镰刀菌烯醇、赭曲霉毒素、T2毒素、伏马毒素B1、展青霉素等真菌毒素的脱除效果较好;后者则集中体现在红球菌、芽孢杆菌、假单胞菌及酵母,依靠微生物代谢的方式对上述毒素进行降解。通过对研究报道的归纳和总结,概述了常见的真菌毒素脱除菌株及其代谢机制的研究进展,以及其在农产品真菌毒素脱毒方面的创新性变革。     

细菌降解黄曲霉毒素B1的研究进展

黄曲霉毒素B1是目前已发现的黄曲霉毒素中毒性最强的一种,其具有强肝毒性、高致突变性和高致畸性。广泛存在于农产品及饲料食品中,对人类健康存在严重威胁,同时对粮食和畜牧业造成严重的经济损失。细菌降解黄曲霉毒素B1是一种有效、安全和环保的解毒方法,该文通过对黄曲霉毒素B1降解的影响因素、细菌胞外酶和胞内酶等对黄曲霉毒素B1的降解机理以及黄曲霉毒素B1降解菌活性产物的应用研究等方面对细菌降解黄曲霉毒素B1进行了论述,并对细菌降解黄曲霉毒素B1应用前景进行展望,为以后更进一步研究提供较为全面的资料。     

生物法防治黄曲霉毒素B1研究进展

黄曲霉毒素具有极强的致癌、致畸和致突变作用。受黄曲霉毒素污染的粮食不仅给人体和动物的健康带来严重危害,也给食品、畜牧等行业造成巨大经济损失。目前,黄曲霉毒素降解方法研究已成为各国科研工作者的一个热点。生物法降解黄曲霉毒素较物理、化学等方法具有安全系数高、特异性强、绿色清洁等独特优势,被视为最具发展前景和潜力的降解方法。利用微生物菌体的吸附作用、微生物酶解作用、微生物代谢作用等对黄曲霉毒素进行脱除,已逐渐成为生物法消减黄曲霉毒素的重要研究方向。通过筛选和改造获得可脱除黄曲霉毒素的优良菌株;通过分离、提取、纯化等手段获得高纯度和高活性的微生物源解毒产物;通过改进和优化获得最佳脱除工艺等,已成为研究生物法脱除黄曲霉毒素的重要手段和突破口。本文主要对国内外生物法防治黄曲霉毒素B_1的研究进行综述,并对今后生物防治的发展方向提出一些设想。     

枯草芽孢杆菌纤维素酶基因整合载体的构建

目的:以枯草芽孢杆菌(Bacillus subtilis)为宿主,构建纤维素酶基因整合表达载体,获得能够表达纤维素酶并且降解纤维素的工程菌。方法:通过聚合酶链式反应(polymerase chain reaction,PCR)从B.subtilis LN基因组中克隆同源片段M1、M2基因片段,以质粒pGEM-T为载体,将同源片段M1、M2、启动子P43和葡萄糖苷酶基因CelKg连接在一起构建整合载体pGEM-Kmpgmt,并采用双交换同源重组的方式将其转化进入B.subtilis LN基因组中。结果:通过PCR和双酶切验证整合载体构建完成,并成功整合到野生型B.subtilis LN中,获得重组菌B.subtilis Kpg。刚果红染色结果显示重组菌对羧甲基纤维素钠有降解作用。改良培养基37℃条件下摇瓶培养,重组菌B.subtilis Kpg生长至18 h时上清液中纤维素酶活力比野生型B.subtilis LN提高了115%。     

黄曲霉毒素B1降解菌株的筛选及鉴定

该研究以香豆素为唯一碳源,从豆类发酵食品、土壤、动物肠道及其内容物中筛选黄曲霉毒素B1（AFB1）降解菌株;然后通过复筛,从中筛选出AFB1降解能力较好的菌株,并对其降解作用与吸附作用进行区分;最后,通过形态观察、生理生化试验及分子生物学技术对其进行鉴定。结果表明,共筛选得到9株AFB1降解菌株,其中菌株YC2的AFB1降解能力最强,AFB1降解率达到90.7%,并确定菌株YC2通过降解作用去除AFB1。最后,菌株YC2被鉴定为枯草芽孢杆菌（Bacillus subtilis）。     

拮抗黄曲霉枯草芽孢杆菌21-1-2发酵条件的优化

以花生原产地土壤源拮抗黄曲霉（Aspergillus flavus）枯草芽孢杆菌（Bacillus subtilis）21-1-2为研究对象,抑菌圈直径为响应值,通过单因素试验和响应面试验,对其发酵条件进行优化。结果表明,Bacillus subtilis 21-1-2的最佳培养条件为培养时间72 h、培养温度为36 ℃、初始pH值6.7、转速188 r/min。在此优化条件下,Bacillus subtilis 21-1-2的平均抑菌圈直径为27.42 mm,是优化前（14.36 mm）的1.9倍。     

抗单增李斯特菌枯草芽孢杆菌C3增菌培养条件优化

枯草芽孢杆菌对单增李斯特菌有强烈抑制作用,该文对其增菌培养基和培养条件进行优化,为今后将其应用于食品和饲料奠定基础。在对培养基成分和培养条件进行单因素试验的基础上,设计5因素4水平正交试验对培养基成分进行优化。结果表明,培养基成分优化为葡萄糖1.0%,酵母浸粉1.0%,NaCl 0.5%,KH2PO4 0.2%,MgSO4·7H2O 0.2%,培养条件优化为pH5.4,装液量50 mL/250 mL,接种量3%,温度37 ℃,150 r/min培养14 h,在此条件下,活菌数可达到7.1×1010 CFU/mL,比优化前提高了7.89倍。     

Bacillus subtilis AprX involved in degradation of a heterologous protein during the late stationary growth phase

In Bacillus subtilis, extracellular protease-deficient mutants have been used in attempts to increase the productivity of heterologous proteins. We detected protease activity of AprX using protease zymography in the culture medium at the late stationary growth phase. An alpha-amylase-A522-PreS2 hybrid protein, in which the PreS2 antigen of human hepatitis B virus (HBV) is fused with the N-terminal 522-amino-acid polypeptide of B. subtilis alpha-amylase, has been produced in multiple-protease-deficient mutants. The B. subtilis KA8AX strain, which is deficient in eight extracellular proteases and AprX, did not show the proteolysis of alpha-amylase-A522-PreS2 in the late stationary growth phase. Moreover, the production of alpha-amylase-A522-PreS2 was about 80 mg/l, which was eight times higher than that by the KA8AX strain previously reported. In addition, we showed the degradation of the heterologous protein by AprX that leaked to the culture medium (probably caused by cell lysis) during the late stationary growth phase.     

Viability of probiotic micro-organisms (Lactobacillus acidophilus La-5 and Bifidobacterium animalis subsp. lactis Bb-12) in ice cream

The purpose of this research was to determine the survival of two probiotic micro-organisms in ice creams (4% fat). The micro-organisms were Lactobacillus acidophilus La-5 and Bifidobacterium animalis subsp . lactis Bb-12 . To meet this objective, an ice cream mixture was formulated and subjected to three treatments. Treatment 1 was inoculated with L. acidophilus , treatment 2 with B. lactis and the third treatment was inoculated with a mixture of both bacteria inoculated in 1 : 1 proportions. The inoculation was with 4% culture for each treatment. The final products were stored at −25°C for 60 days. The ice cream inoculated with L. acidophilus had a final concentration of 2 × 10 ⁶ cfu/g and the survival rate was 87%. The treatment inoculated with B. lactis had a final concentration of 9 × 10 ⁶ cfu/g, with a logarithmic decrease of 10%. When both micro-organisms were inoculated together, the survival rate was 86%.     

多菌混合发酵产纤维素酶及生物法预处理秸秆的研究

对实验室分离筛选的3株绿色木霉和6株枯草芽孢杆菌的生长及产酶情况进行了研究,综合确定绿色木霉绿2与芽孢杆菌S3为混合菌中产纤维素酶酶活最高的组合。在此基础上,采用解脂假丝酵母处理高粱秸秆。先将解脂假丝酵母的种子培养液按照3%的接种量接种到发酵产酶培养基中,隔24 h将绿色木霉绿2的孢子悬浮液按照2.67%的接种量接种到发酵产酶培养基中,再隔12 h将芽孢杆菌S3的种子培养液按照5.33%的接种量接种到发酵产酶培养基中,测定出的滤纸酶活（FPA）最高,为389.89 U/mL,比优化前提高了14.30%。     

NATTO BACILLUS CONTAINS A LARGE AMOUNT OF WATER-SOLUBLE VITAMIN K (MENAQUINONE-7)

Bacillus natto (Bacillus subtilis natto) was cultivated, and an analysis was conducted after performing lysozyme treatment and water extraction of the culture supernatant and the B. subtilis natto cells. The intracellular existence of a large amount of water‐soluble vitamin K (Menaquinone‐7: MK‐7) was established. The existence of small amounts of other types of vitamin K2 including MK‐4 and PK was also confirmed in the culture solution (water‐soluble fractions). The amount of water‐soluble menaquinone‐7 in Bacillus was 85 µg/g wet weight of the bacteria, and the amount was equivalent to more than 100 times as much as that contained in the culture solution (0.02 µg). Gel filtration using Sephacryl S‐200HR revealed that the molecular weight of the water‐soluble menaquinone‐7 is approximately MW 200,000, and isoelectric focusing revealed a behavior similar to that of protein, with a pI of about 4.2. A rabbit antibody was prepared with this water‐soluble vitamin K as the antigen. By using the Ouchterlony method, the antibody showed a reaction (precipitation line) with the water‐soluble menaquinone‐7 prepared from both the intracellular fraction and the extracellular culture solution, and it was found through the antigen–antibody reaction that the menaquinone‐7 disappears from the supernatant of the reactant (the water‐soluble menaquinone‐7 is thus neutralized). Based on these results, it was inferred that the vitamin K produced by B. subtilis natto becomes water‐soluble by forming an intracellular complex with protein and is released in the extracellular fraction during the culture process.     

Degradation of cyanuric acid in soil by Pseudomonas sp. NRRL B-12227 using bioremediation with self-immobilization system

The rates of degradation of cyanuric acid, a key intermediate in a metabolic pathway of s-triazine herbicides, were measured for Pseudomonas sp. NRRL B-12227. The rate of degradation was affected by the rate of cyanuric acid transport through cell membranes and the activity of cyanuric acid amidohydrolase inside the cells. At low concentrations of cyanuric acid, the acclimation of cells to cyanuric acid and/or added nutrients effectively enhanced the degradation rate. The strain was also applied to bioremediation using a Bioremediation with Self-Immobilization System (BSIS), in which Pseudomonas sp. NRRL B-12227 cells were co-immobilized with Bacillus subtilis, the latter of which secretes a viscous polymer, in a shallow layer of soil packed in a column. More than 70% of the Pseudomonas sp. NRRL B-12227 cells were co-immobilized with the B. subtilis in a 7.5 cm layer of the packed soil by self-aggregation. More than 60% of the 1 mM cyanuric acid supplied to the packed soil was degraded in this layer during a 72 h period.     

食（药）用蕈菌中高抑菌活性菌株筛选及培养基优化

对4个不同属24株食(药)用蕈菌对11株指示菌抑菌活性进行研究,通过初筛模型,从中筛选出3株功能菌,6株指示菌。对初筛菌株进一步复筛,确定功能菌株H2与枯草芽孢杆菌、沙门氏菌、蜡状芽孢杆菌为培养基优化的出发菌株和指示菌。通过响应面分析优化培养基配方,结果表明,当麦芽糖40.9g/L、蛋白胨11.2g/L、KH2PO4 2.1g/L、MgSO4 ·7H2O 1.1g/L时,H2对枯草芽孢杆菌、沙门氏菌、蜡状芽孢杆菌的抑菌活性均较理想,其抑菌圈半径分别达到3.513、4.610、8.800mm。