Decrease of Lipid Oxidation for Dried Shrimp (Acetes chinensis) Preservation Using Alkaline Lipase Hydrolysis Technology

ABSTRACT

In this study, the degreasing technology using alkaline lipase hydrolysis for Chinese dried shrimp (Acetes chinensis) was investigated, with the purpose of decreasing lipid oxidation during dried shrimp preservation. The salt, moisture, and lipid contents of the shrimp were 6.01, 32.51, and 2.95%, respectively. The optimum enzymatic hydrolysis condition for effective decrease of shrimp lipid was obtained: lipase concentration 40 U/mL, pH 10, soaking time 60 min, soaking temperature 30°C, and shrimp/liquid ratio 1:20 (w:v). Under this optimum condition, the residual lipid of the shrimp was reduced to 2.28%, and the degreasing rate reached 49%. During 30-day preservation, the thiobarbituric acid-reactive substances (TBARS) value (0.185 mg/kg of dried shrimp and 0.131 mg/kg of degreased dried shrimp at Day 30) of degreased shrimp was lower than the shrimp without degreasing, indicating alkaline lipase hydrolysis could effectively prevent lipid oxidation and inhibit oxidative rancidity during dried shrimp preservation.     

一株高产脂肪酶产生菌16S rDNA的序列分析

[目的]对分离获得的高产脂肪酶菌株进行鉴定,为其改造和更好利用奠定基础.[方法]对从食堂下水道中分离获得的一株高效产脂肪酶细菌(JLΠ-4)进行培养,提取其基因组DNA.设计16S rDNA通用引物,扩增16S rDNA基因片段,并连接到pUC19-T载体上,转化大肠杆菌DH5X,经PCR鉴定的阳性克隆摇菌培养后测序.[结果]提取获得较高质量的基因组DNA,扩增获得新分离菌株16S rDNA基因片段,长度为1528 bp,BLAST相似性比对分析结果表明,其与伯克霍尔德氏菌16S rDNA序列相似性达97%,是一株与伯克霍尔德氏菌最近的革兰氏阴性菌.[结论]初步将高产脂肪酶细菌JTΠ-4鉴定为唐菖蒲伯克霍尔德菌.     

天然产物抑制脂肪酶活性的研究进展

胰脂肪酶是一种由胰腺分泌的脂肪分解酶,能够分解人体摄人的脂肪类物质,脂肪分解后才能被人体吸收。因此．那些具有胰脂肪酶抑制活性的物质具有减少人体脂肪吸收的作用。通过研究胰脂肪酶抑制剂可以获得防治肥胖的物质。天然产物中含有多种具有肪酶抑制作用的活性成分。本文从不同种类和来源上对天然源脂肪酶抑制剂进行了总结．为天然产物在脂肪酶抑制剂的筛选上提供一定的文献基础。     

植物油对刺糖多孢菌生长及其合成多杀菌素能力的影响

为研究不同种类植物油对刺糖多孢菌生长及其合成多杀菌素能力的影响,探索提高多杀菌素产量的方法,在发酵培养基中分别添加葵花油、花生油、大豆油、芝麻油、橄榄油和菜籽油,研究了其对菌体生长、脂肪酶活性和多杀菌素产量的影响,并利用RT-PCR对脂肪酶基因及多杀菌素合成相关基因的转录水平进行分析。结果表明:6种供试植物油对菌体生长和多杀菌素产量的影响程度不同,依次为菜籽油橄榄油花生油芝麻油葵花油大豆油,其中菜籽油有利于诱导脂肪酶的表达、延缓菌体的衰亡和延长产素期,脂肪酶活力、菌体生物量和多杀菌素产量分别提高310.09%、8.97%和33.94%;脂肪酶基因和多杀菌素合成基因的转录强度也有明显提高。因此,菜籽油是其最佳的辅助性脂类碳源。     

The effect of exogenous enzyme supplementation on growth performance and digestive enzyme activities in Oreochromis mossambicus fed kikuyu‐based diets

The utilization of plant‐based diets in fish is limited by the presence of anti‐nutrients, which bind to dietary nutrients and reduce their bioavailability. Exogenous enzyme supplementation may alleviate the effects of anti‐nutrients and improve feed utilization. In this study, a commercial multi‐enzyme Natuzyme50^® was added to a kikuyu‐based diet at a rate of 0 (control), 0.25, 0.5, 0.75 and 1.00 g kg^?1 DM. Each diet was fed to triplicate groups of Oreochromis mossambicus for 60 days. All fish fed diets containing Natuzyme50^® had higher (P < 0.05) growth performance compared with those fed the control diet. Fish fed the diet containing 0.50 g kg^?1 had the best growth performance, highest protein digestibility and the highest levels of digestive enzyme activities. When Natuzyme50^® was supplemented above 0.50 g kg^?1 in the diet, growth performance and enzyme activities decreased. The improved growth performance observed with Natuzyme50^® supplementation was attributed to the presence of enzymes such as cellulase, xylanase and phytase in the cocktail that are not naturally produced by fish. The presence of these enzymes released bound nutrients that would have not been available to the fish. Natuzyme50^® supplementation also increased (P < 0.05) the activities of endogenous enzymes, improving the efficacy of the digestive process. The optimal dietary level of Natuzyme50^® for optimal growth performance in O. mossambicus was 0.62 g kg^?1 DM feed. Cost benefit analysis indicate that adding up to 0.5 g Natuzyme50^® kg^?1 in the diet results in higher profits as the increased growth attained offset the additional cost of Natuzyme50^®.     

脂蛋白脂酶研究进展

脂蛋白脂酶(LPL)是动物组织中脂肪沉积的关键酶,是甘油三酯降解为甘油和游离脂肪酸(FFA)反应的限速酶,在脂质代谢和转运过程中起着重要作用。脂蛋白脂酶基因的表达具有特异性,营养等因素能够影响动物LPL基因的表达和LPL活性。论文综述了LPL的生物学功能、LPL在脂肪沉积中的作用及其在单胃动物和反刍动物中的研究现状。     

细菌A007菌株脂肪酶的纯化及性质研究

微生物产生的脂肪酶种类繁多、pH和温度的适应范围广,有十分广泛的应用。细菌在油脂培养基中30℃培养24 h,经1次硫酸铵沉淀和2次Sephadex G-75排阻层析得到电泳纯脂肪酶。经SDS-PAGE测得其分子量为29.5 ku,经酶促反应测定最适温度为40℃,最适pH为8.0,表现出较好的温度和pH稳定性。     

鲤脂蛋白脂肪酶基因特性、表达分布、重组蛋白获得及酶活性比较

为研究鲤脂蛋白脂肪酶(Cc LPLs)的基因特征、时空表达分布及酶活性,实验利用基因组同源搜索获取鲤CcLPLs同源基因并分析其序列特征;通过荧光定量PCR(qPCR)方法对CcLPLs在不同组织的表达进行分析;采用原核表达系统获取CcLPLs重组蛋白,并使用对硝基苯酚法测定各重组蛋白的酶活性。结果显示,鲤基因组中挖掘到5个CcLPLs基因(CcLPLA1a、CcLPLA1b、CcLPLA2a、CcLPLA2b*和CcLPLBa),经验证,CcLPLA2b*是假基因,共线性分析显示,鱼类特有基因组加倍过程中出现基因丢失的现象,而鲤特有的基因组加倍致使鲤存在5个CcLPLs。CcLPLA1a和CcLPLA1b核苷酸序列和氨基酸序列相同,同源性分析显示,CcLPLBa与CcLPLA1s的同源性为64%,与CcLPLA2a同源性为50.8%。qPCR结果显示,CcLPLs的表达量在肝脏、心脏、脂肪、肌肉、脑、肠道和脾脏中依次降低,在各个组织中,各基因表达量从高到底依次为CcLPLA1s、CcLPLA2a和CcLPLBa。鲤正常投喂、饥饿及再投喂状态下CcLPLA1s和CcLPLA2a在肝脏、...     

Pancreatic triglyceride lipase is involved in the virulence of the brown planthopper to rice plants

The brown planthopper (BPH), Nilaparvata lugens, an important rice insect pest, can enhance its virulence to BPH-resistant rice within as short a span as several generations. Here, we cloned a pancreatic triglyceride lipase (PTL) gene (NlPTL) in N. lugens, and found that its mRNA level was higher in the high virulence population (fed on variety Rathu Heenati, P-RH) than in the low virulence population (fed on variety Taichung Native 1, P-TN1). Knocking down NlPTL caused BPH individuals to spend more time in non-penetration and the pathway phases and less time feeding on the phloem of rice plants; these changes consequently decreased food intake, lipid content, survival rate, and fecundity in the insects. These findings reveal for the first time that PTL in BPH is involved in its virulence to rice plants.     

纳米氧化铈对蛋鸡胰脂肪酶活性及基因表达的影响

本文旨在建立胰脂肪酶实时荧光定量 ＰＣＲ检测方法的基础上研究纳米氧化铈对蛋鸡胰脂肪酶活性及基因表达的影响。试验选择 ２６周龄健康商品蛋鸡 ３８４只,随机分为 ４组,每组８个重复,每个重复 １２只鸡。以玉米 －豆粕型饲粮为基础饲粮,在基础饲粮中分别添加 ０（Ⅰ组）、３０（Ⅱ组）、６０（Ⅲ组）和 ９０ｍｇ／ｋｇ（Ⅳ组）的纳米氧化铈,试验期 ７周。结果表明：１）本试验建立的胰脂肪酶实时荧光定量 ＰＣＲ检测方法具有线性关系好,特异性、敏感性、重复性高等特点,可用于检测胰脂肪酶 ｍＲＮＡ表达水平;２）Ⅲ组胰脂肪酶活性显著或极显著高于Ⅰ组和Ⅳ组（Ｐ＜０．０５或 Ｐ＜０．０１）,胰脂肪酶 ｍＲＮＡ表达水平显著高于其他各组（Ｐ＜０．０５）。由此得出,饲粮中添加 ６０ｍｇ／ｋｇ纳米氧化铈可显著提高蛋鸡胰脂肪酶活性,上调胰脂肪酶 ｍＲＮＡ表达水平。