混合乳酸菌发酵改善罗非鱼蛋白酶解液风味的研究

通过嗜热乳链球菌（Streptococus thermophilus）和保加利亚乳杆菌（Lactococcus bulgarcus）混合发酵,改善罗非鱼（Oreochromis niloticus）下脚料蛋白酶解液风味,采用响应面设计试验考察乳酸菌发酵时间（X1）、温度（五）及接种量（恐）对酶解液风味感官评分值（Y）的影响,并利用同时蒸馏萃取与气相色谱-质谱（GC—MS）联用技术测定挥发性成分。结果表明,响应面分析法（RSM）优化的乳酸菌发酵条件为时间9h,温度45℃,接种量16％,预测风味感官评分值为4．1;酶解液发酵后的挥发性成分由原来的27种增加至33种,增加的主要是酯类物质,另外产生了辛酸及十六醛等风味物质。乳酸菌发酵能减弱罗非鱼酶解液的腥味,但脱苦效果不明显。     

微生物发酵对罗非鱼下脚料蛋白酶解液脱腥去苦效果比较

以嗜热链球菌(Streptococus thermophilus)、保加利亚乳杆菌(Lactobacillus bulgaricus)和瑞士乳杆菌(L.helveticus)及2种酿酒酵母菌(Saccharomyces cerevisiae)为菌种,对罗非鱼(Oreochromis niloticus)下脚料蛋白酶解液进行发酵,利用感官评定法,比较不同微生物发酵对酶解液脱腥去苦效果.试验结果表明,乳酸菌脱腥效果优于酵母菌,其中以嗜热链球菌脱腥效果最好,其适宜的发酵条件为接种量10%,发酵温度42℃,发酵时间9 h.微生物发酵去苦效果不明显.     

5种乳酸菌对奥尼罗非鱼免疫和抗病力的影响

选用体质量约3．49 g的奥尼罗非鱼,分别投喂基础饲料（空白组）和添加相同水平的嗜酸乳杆菌、植物乳杆菌、戊糖乳杆菌、鼠李糖乳杆菌、粪肠球菌的试验饲料。饲料中的乳酸菌数分别为1．30×103、5．10×108、2．97×108、3．03×108、2．30×108、3．47×108 cfu／g ,养殖期为8周,试验结束后采集血液并留部分鱼进行72 h的嗜水气单胞菌感染试验,计算72 h内的存活率。结果显示,植物乳杆菌组、戊糖乳杆菌组、鼠李糖乳杆菌和粪肠球菌组血清碱性磷酸酶活性均有不同程度升高,其中戊糖乳杆菌组最高,且显著高于嗜酸乳杆菌组;鼠李糖乳杆菌和粪肠球菌组血清抗超氧阴离子自由基能力显著高于其他各组;鼠李糖乳杆菌组血清溶菌酶活性显著高于空白组。注射嗜水气单胞菌12 h后,各添加组罗非鱼存活率均高于空白组,24～48 h ,鼠李糖乳杆菌组和粪肠球菌组存活率显著高于空白组,72 h时鼠李糖乳杆菌组存活率显著高于空白组。饲料中添加乳酸菌能提高奥尼罗非鱼免疫、抗氧化能力及抗嗜水气单胞菌感染能力,其中鼠李糖乳杆菌和粪肠球菌效果显著。     

罗非鱼下脚料蛋白水解液对钝顶螺旋藻生长的影响

将罗非鱼下脚料蛋白水解液添加到Zarrouk培养基中对螺旋藻进行混合营养培养,研究罗非鱼下脚料蛋白水解液对螺旋藻的生物量、叶绿素、藻蓝蛋白含量及氮素代谢的影响.试验结果表明,添加0.5‰～5.0‰的罗非鱼下脚料蛋白水解液,均能增加螺旋藻的生物量与叶绿素含量,其中以添加3.0‰时增幅最大,分别比对照组增加了40.4‰与35.4‰,同时可明显提高硝酸还原酶活性,但对藻蓝蛋白含量影响不大.添加罗非鱼下脚料蛋白水解液对藻液体系的pH值有一定的缓冲作用.     

海洋红酵母RH1菌株发酵培养条件的研究

该研究比较了不同碳源、氮源、无机盐对海洋红酵母菌（Rhodotorula sp.）RH1菌株发酵产量的影响,通过葡萄糖、蛋白胨、酵母膏和硫酸镁（MgSO4）4因素3水平的正交试验,确定了RH1菌株的最优培养基为蛋白胨10 g.L-1,酵母膏15 g.L-1,葡萄糖20 g.L-1,MgSO40.25 g.L-1,磷酸二氢钾（KH2PO4）0.25 g.L-1,氯化钠（NaCl）10 g.L-1。结果显示,该菌株最佳摇瓶发酵条件为接种量10%,初始pH 5.0,摇瓶装液量80 mL/500 mL三角瓶,培养温度28℃,经48 h培养,菌量可达10.46×108cfu.mL-1,比优化条件前提高23.9%。还进行了RH1菌株25 L发酵罐扩大培养试验,在接种量为8%、初始pH 5.0、搅拌速率350～400 r.min-1、通气量9 L.min-1、温度28℃的条件下,经28 h的培养,菌量可达33.6×108cfu.mL-1。预计通过连续补料的方式进行培养,有望进一步提高菌量。     

一株海洋红酵母的鉴定及其培养基的优化

通过菌落形态、培养特征和生理生化特征的测定,初步确定海洋红酵母HN-3为红酵母属的胶红酵母。比较不同的碳源、氮源、酵母膏质量分数和海水盐度对该酵母生长的影响,优化其培养基。试验结果表明,最佳培养基为2%葡萄糖、1.5%蛋白胨、1%酵母膏,盐度30。在该培养条件下,酵母菌HN-3的产菌量达到4.80×107cfu/mL,比初始发酵条件下的产菌量(4.20×107cfu/mL)提高了14.3%。     

罗非鱼肠道益生菌的筛选、鉴定及其抑菌性能研究

采用“先筛选后分离”方式对活体罗非鱼肠道菌进行分离,选取革兰氏阳性接触酶阴性的细菌,反复冻融法制备模板DNA,PCR扩增并测定了菌株的16S rDNA序列,得到1株乳酸乳球菌、1株德氏乳杆菌.采用牛津杯法测定其对病原菌的抑菌效果,结果表明,这2株乳酸菌对大肠杆菌、金黄色葡萄球菌有不同程度的抑制作用,为生态养鱼提供了发酵菌种.     

枯草芽孢杆菌培养基配方优化的研究

枯草芽孢杆菌培养基的组分是由葡萄糖、蛋白胨、酵母膏、磷酸二氢钾、碳酸钙等5种原料构成，采用L1（4^5）正交表，将5种原料作为枯草芽孢杆菌培养有影响的因素，通过试验数理统计的直观和理论分析，对其配方进行优化：试验结果表明，当培养基的配方为无水葡萄糖3．50g／L、蛋白胨0．83g／L、酵母膏0．50g／L、磷酸二氢钾0．35g／L和碳酸钙0．25g／L，温度（34±2）℃时，培养16h即可达到生长峰值。由于枯草芽孢杆菌光学密度（optical density，OD）与活菌数量的关系：Y=0．5182x^2＋1．4462x＋1．9714（r=0．996343），接种的枯草芽孢杆菌由1．9714×10^8cfu／mL提高到3．3124×10^8cfu／mL。优化的枯草芽孢杆菌培养基条件能有效促进枯草芽孢杆菌生长。     

鰤鱼诺卡氏菌培养条件及培养基的优化

对鰤鱼诺卡氏菌（Nocardia seriolea）ZJ0503的增菌培养基和生长条件进行优化。研究了温度、盐度、初始pH对鰤鱼诺卡氏菌生长的影响,并通过单因素试验对培养基的碳源、氮源和无机盐成分进行了筛选,采用正交实验法对培养基各主要成分的添加量进行了优化。结果表明,鰤鱼诺卡氏菌最适宜生长条件为温度25 ℃、盐度5、pH 6.5±0.2;经筛选,鰤鱼诺卡氏菌培养基中最佳碳源是葡萄糖,最佳氮源是酵母粉,促生长作用最强的2种无机盐是磷酸氢二钾（K2HPO4）和氯化钙（CaCl2）;确立了培养基优化配方为葡萄糖20 g·L-1,酵母粉15 g·L-1,K2HPO4 0.75 g·L-1,CaCl 20.2 g·L-1（单独灭菌）,氯化钠（NaCl2）5 g·L-1,pH 6.5±0.2。     

投喂乙醇假丝酵母对罗非鱼生长、免疫和肠道菌群的影响

为探究乙醇假丝酵母(Candida ethanolica GXU01)在罗非鱼养殖中的益生潜能,为罗非鱼可持续养殖寻找生态友好的饲用添加菌,该研究将乙醇假丝酵母作为饲料添加菌饲喂尼罗罗非鱼(Oreochroms niloticus),通过测定罗非鱼的生长性能、肠道消化酶、血清非特异性免疫指标、肠道微生物群落结构以及用无乳链球菌(Streptococcus agalactiae)对罗非鱼进行攻毒试验,全面评价了乙醇假丝酵母对罗非鱼生长及其免疫力的影响。结果表明,摄食乙醇假丝酵母可以使罗非鱼的生长性能、消化酶活性、血清溶菌酶活性和补体C3含量显著提高(P0.05)。投喂乙醇假丝酵母后,罗非鱼肠道中梭杆菌门、鲸杆菌属(Cetobacterium)和艾克曼菌属(Akkermansia)等有益菌群的丰度显著上调,蓝细菌门大幅减少。攻毒试验中,摄食酵母饲料的罗非鱼成活率增加26.66%。研究表明乙醇假丝酵母对罗非鱼肠道消化能力和免疫抗病能力均有促进作用。     

产虾青素海洋酵母菌YS-185的鉴定及发酵条件优化

以26S rDNA法将实验室保藏的1株产虾青素的海洋酵母菌YS-185鉴定为粘红酵母。以海洋酵母菌YS-185为试验菌株,运用摇瓶发酵优化的方式,探索培养基组分和发酵工艺条件对该菌发酵的影响。实验结果表明,该菌生长最适培养基组分为葡萄糖8 g/L、蛋白胨8 g/L,最适生长起始pH值为5.5、转速220 r/min、接种量8%、温度20℃;虾青素合成的最佳培养基组分葡萄糖8 g/L、蛋白胨8 g/L,最佳虾青素合成条件:pH 5.5,转速220 r/min,接种量8%,培养温度25℃。发酵优化后的虾青素产量2.670μg/ml,较优化前的1.572μg/ml提高了69.8%。温度对酵母菌的生长和虾青素的合成都有显著影响。海洋酵母菌YS-185优化后的发酵条件有规模化生产虾青素的应用潜力。     

不同乳酸菌对发酵草鱼品质的影响

为探明不同乳酸菌对发酵草鱼微生物数量和理化性质的影响,进一步提高发酵鱼制品的品质,实验对草鱼背部肌肉经不同乳酸菌(植物乳杆菌、戊糖片球菌和副干酪乳杆菌)发酵后制品的微生物数量、pH、总酸、水分含量、白度、氨基酸态氮、硫代巴比妥酸和挥发性盐基氮等进行分析,探究不同乳酸菌在草鱼发酵过程中(0～15d)对其品质的影响.结果显...     

乳酸菌在青贮中的应用及研究进展

青贮饲料是一个复杂的微生物共生体系,主要包括乳酸菌、酵母菌、芽孢杆菌、乙酸菌、梭状芽饱杆菌等,其中以乳酸菌的数量和种类最多,也是在青贮饲料发酵中起主要作用的微生物。着重介绍了乳酸菌微生物青贮剂的种类、选作微生物青贮剂的乳酸菌需符合的条件,阐述了乳酸菌微生物青贮剂的作用机制、添加效果以及影响因素,并对乳酸菌微生物青贮剂近年的研究进展和应用现状进行了总结,指出了乳酸菌微生物青贮剂的未来发展趋势将由单一型向复合型方向发展,同时需将现代基因工程、遗传工程技术引入乳酸菌微生物青贮剂,以开发新型制剂。     

Lactic acid bacteria effective for regulating the growth of contaminant bacteria during the fermentation of <Emphasis Type="Italic">Undaria pinnatifida</Emphasis> (Phaeophyta)

ABSTRACT:   Lactic acid fermentation of seaweed is a recent topic and quite limited information is available on culture conditions. To know the suitable strains for use as a starter culture for seaweed fermentation, 14 lactic acid bacteria (LAB) strains, including 11 species, were tested in culture conditions prepared with or without salt. A commercial product of Undaria pinnatifida powder was used as a substrate for fermentation without sterilizing. Starter-suitability of the LAB strains was assessed from their predominance after culture. Among the tested strains, Lactobacillus brevis, Lactobacillus plantarum, Lactobacillus casei and Lactobacillus rhamnosus showed high (>90%) predominance in their cultures, while control cultures prepared without inoculation of LAB did not show any detectable growth of acid producing bacteria and spoiled. A total of 102 strains not showing acid producing activity were isolated and characterized from spoiled cultures, and all the isolates were observed as Bacillus strains, including 64 strains (62.7%) and 16 strains (15.7%) of a Bacillus cereu s-related and B. fusiformis -related species, respectively. The Undaria substrate before fermentation contained culturable microorganisms at 1.4–3.1 × 10² CFU/g, but the Bacillus cereu s-related strain was not a major composition, suggesting a concern of selective growth of the Bacillus cereu s-related strain during the spoiled fermentation.     

Diet supplemented with probiotic for Nile tilapia in polyculture system with marine shrimp

The aim of this study was to assess the effect of a probiotic (Lactobacillus plantarum) supplemented diet on Nile tilapia (Oreochromis niloticus) in a polyculture system with marine shrimp (Litopenaeus vannamei) as regards culture performance, hematology, and gut bacterial microbiota. Ten 20-m2 pens were arranged in one earthen pond and stocked with 2 fish (41.9 g) m⁻² and 10 shrimp (2.3 g) m⁻², in total of 40 Nile tilapias and 200 shrimp per experimental unit. Tilapia groups in five of the experimental units were fed a commercial diet supplemented with L. plantarum and the other five with an unsupplemented commercial diet (control). After 12 weeks of culture, the tilapia groups fed the probiotic-supplemented diet presented values 13.6, 7.5, and 7.1% higher for feed efficiency, yield, and final weight, respectively. Viable culturable heterotrophic bacteria counts were reduced, and the number of lactic acid bacteria was increased in the gut of fish and shrimp fed the probiotic-supplemented diet. Hematological analyses showed higher number of thrombocytes and leukocytes in tilapia fed the supplemented diet. L. plantarum utilized in this study colonized the gut of tilapia and shrimp and resulted in reduced number of total bacteria and increased tilapia final weight and feed efficiency.     

降解亚硝酸盐的大山芽孢杆菌JY-1的分离、鉴定及其作用

为得到稳定高效降解亚硝酸盐的益生菌,通过菌株富集分离培养、菌株鉴定、发酵培养基优化等实验对菌株进行了分离、鉴定,对菌株降亚硝酸盐效果进行了分析,并克隆了亚硝酸盐还原酶基因.结果显示,从养殖池塘、污水处理厂等5处混合水体中分离、筛选出一株具有亚硝酸盐降解能力的菌株,命名为JY-1.菌株生理生化和16S rDNA序列分析显...     

Comparison of Lactic Acid Bacteria Fermentation with Acid Treatments for Chitosan Production from Shrimp Waste

The traditional procedure for chitosan production involves use of a strong acid (HCl) for demineralization of chitin. This study reports application of a mixed culture of lactic acid bacteria (Lactobacillus plantarum, Lactobacillus acidophilus, and Lactobacillus lactis) fermentation in demineralization of chitin for chitosan production from shrimp waste. Chitosan produced from shrimp waste with lactic acid bacteria fermentation at 30°C for 72 h or 1 M lactic acid treatment at room temperature for 2 h followed by alkaline treatments (0.5 M NaOH at 25°C for 4 h followed by 12.5 M NaOH at 70°C for 10 h) contained very low protein (0.8–1.1%) and ash (<0.01%) contents with the same solubility (100%) as those of chitosan produced with hydrochloric acid treatment. Lactic acid bacteria fermentation and lactic acid treatment may be utilized in chitosan production from shrimp waste to reduce use of strong chemicals.