NaCl-activated extracellular proteinase from Virgibacillus sp. SK37 isolated from fish sauce fermentation

ABSTRACT:  Virgibacillus sp. SK37 exhibited high extracellular proteolytic activity in skim milk broth containing 10% NaCl. Optimum conditions of the crude proteinase were at pH 8.0 and 65 °C. The proteinase was strongly inhibited by phenylmethanesulfonyl fluoride (PMSF) and preferably hydrolyzed Suc-Ala-Ala-Pro-Phe-AMC, suggesting the serine proteinase with a subtilisin-like characteristic. Proteolytic activity increased with NaCl concentration up to 20%. Ca²⁺ activated the enzyme activity but reduced enzyme stability at 65 °C. Several proteinases with dominant molecular mass (MW) of 81, 67, 63, 50, 38, and 18 kDa were detected on native-polyacrylamide gel electrophoresis (native-PAGE) activity staining in the absence and presence of 25% NaCl. These results demonstrated that Virgibacillus sp. SK37 produced salt-activated extracellular proteinases. Virgibacillus sp. SK37 could be a promising strain for starter culture development used in fish sauce fermentation.     

己酸菌、液体窖泥的发酵罐混合培养及应用的进一步研究

对己酸菌、液体窖泥的混合培养进行了工艺调整以及应用的研究，其结果表明了：采用优质老窖泥一次性获得大量液体窖泥菌种的工艺调整是可行的；采用己酸菌、液体窖泥混合培养液进行窖泥养护的用量是有一定限制的；采用己酸菌、液体窖泥混合培养液进行退化窖泥的养护具有一定的效果，但要彻底改善退化窖泥有一定的难度。     

枸杞果汁发酵过程复合乳酸菌的实时定量检测

利用植物乳植杆菌（Lactiplantibacillus plantarum）、发酵粘液乳杆菌（Limosilactobacillus fermentum）和瑞士乳杆菌（Lactobacillus helveticus）混合菌种进行枸杞果汁发酵。该研究对乳酸菌亚致死修复液的组成和修复温度进行优化,分别针对3株乳酸菌设计特异性引物,利用叠氮溴化丙锭（PMA）-荧光定量聚合酶链式反应（fqPCR）的方法,实时荧光定量检测枸杞果汁发酵过程中乳酸菌活菌数。结果表明,优化修复液的组成为蛋白胨1 g/L、牛肉浸出粉0.3 g/L、氯化钠0.5 g/L、吐温80 0.10 g/L、丙酮酸钠0.09 g/L、过氧化氢酶0.04 g/L、MgCl2 3 mmol/L、Na2HPO4 1 mmol/L、MnCl2 2 mmol/L和FeCl2 2 mmol/L。在27 ℃条件下培养15 min,乳酸菌亚致死细胞修复率达到97%。利用该方法实现了枸杞果汁发酵过程不同乳酸菌的实时定量检测,为今后枸杞果汁发酵生产过程中的微生物动态监测提供了方法。     

中温菌的分离及其应用

从某温泉中分离一株中温菌,生长温度40~50℃,pH 1.5~2.0,中温菌是兼性化能自氧菌,能利用蛋白胨生长。中温菌与T.f菌在紫金山铜矿的浸出对比试验,中温菌比T.f菌浸出速度快1~2倍,考察了影响中温菌浸出的因素。     

生化去除南阳油田污水COD的研究

从南阳油田污水和污泥中分离驯化了一种厌氧菌和一种好氧菌,初步鉴定为假单胞菌属。两种菌都能起到去除油田污水COD的作用,其中,厌氧菌的最适条件为：pH值7~8、磷酸二氢钠添加量0.5g·L^-1、温度20~45℃;好氧菌的最适条件为：pH值6~7、硝酸铵添加量3g·L^-1、磷酸二氢钠添加量0.5g·L^-1、接种量50mL·L^-1、温度20~35℃;在最适条件下,厌氧菌和好氧菌对油田污水COD去除率分别达到44%和84%。     

冰核活性菌体蛋白微冻保鲜虾体的应用研究

本文首次把具冰核活性的菌体蛋白碎片应用在基围虾的低温微冻保鲜保藏技术中，保藏过程中，通过对虾体内各物质的检测，来判断保藏虾体的品质及风味的变化。研究结果表明，微冻保鲜20d后，经感官检测、品质检测和风味检测，其虾体的新鲜度变化趋势有相关性，且虾体的保鲜效果好，保存期长等特点；另外能耗低、易于管理和操作。     

紫外线消毒在回用水中的研究

检测和分析了紫外线消毒器前后中水中大肠杆菌和细菌总数，对紫外线消毒技术用于回用水消毒的可行性作了研究，对于提高水的安全性具有非常重要的意义。     

Corrosion inhibition approach of oil production systems in offshore oilfields

Synthesis and modification of imidazoline were carried out based on review of the corrosion inhibitor development and application for oilfields. A series of imidazoline compounds were synthesised through the solvent dewatering and vacuum dewatering methods. After reaction of imidazoline with ethane oxide, the produced compound was used to react with halogen hydrocarbon and polyphosphoric acid respectively. Finally an agent with performance of corrosion‐inhibition, sterilisation and anti‐scaling was obtained. The structures of the compounds were characterised by the Fourier transformation infrared spectrum. The relationships between corrosion inhibition effectiveness of the compounds and their structures were investigated so as to determine the structure of a novel corrosion inhibitor. The selected corrosion inhibitor was evaluated by a series of experiments to understand the characteristics of imidazoline derivative and some major factors associated with oil production in the oilfields of China. The experimental results showed that this corrosion inhibitor has outstanding performance of corrosion inhibition and sterilization, and is suitable for corrosion inhibition of the oil abstraction systems with high water‐content in the offshore oilfields.     

新型双季铵盐缓蚀杀菌剂的合成及其性能研究

合成了一种新型双季铵盐类缓蚀杀菌剂MBQA,探讨了其合成条件并对其分子结构进行了表征,研究了MBQA缓蚀、杀菌性能和机理.结果表明,MBQA是一种典型的阳极抑制型缓蚀剂,其杀菌性能较甲硝唑有明显改善,远远优于油田普遍使用的"1227".     

硫酸盐还原菌的微生物腐蚀及其防护研究进展

综述了硫酸盐还原菌(SRB)引起微生物腐蚀(MIC)的各种机理及其形成生物膜的腐蚀作用,以及利用微生物防治硫酸盐还原菌腐蚀的研究进展.