冻干嗜酸乳杆菌菌粉制备及特性研究

通过对嗜酸乳杆菌发酵曲线的测定,初步掌握了该菌的生长、繁殖和代谢规律。在此研究基础上进行的发酵试验结果表明,采用20g/kg接种量,37℃恒温静置培养6h,活菌数最多,菌龄处于对数生长期末期,适宜冻干;对几种复合保护剂的保护效果进行研究,得到冻干复合保护剂的最佳配比为:蔗糖40g/kg,甘油10g/kg,L-cys1g/kg和Vc1g/kg。

真空冷冻干燥与喷雾干燥长双歧杆菌的工艺比较研究

为有效延长双歧杆菌的保存期和耐受性,利用真空冷冻干燥及喷雾干燥法制备活性菌粉。研究两种干燥方法的工艺参数,并对干燥得到的活性菌粉性能进行比较。真空冷冻干燥法制备的长双歧杆菌活性菌粉的活菌数为7.98×109CFU/g、存活率90.9%、含水量3.8%,4℃保藏90d后活菌数为2.5×108CFU/g,菌粉的水溶性好;喷雾干燥法制备的活性菌粉的活菌数为4.4×109CFU/g、存活率82.2%、包埋率71.9%、含水量5.6%,4℃保藏90d后活菌数为4×108CFU/g,菌粉在水中的溶解时间较长。真空冷冻干燥成本较高、操作时间长、菌粉的保藏期较短;而喷雾干燥工艺简单、生产成本低、工作效率高,包埋的菌粉保藏期较长。

Biodiversity and Enzyme Activity of Indigenous Cellulolytic and Amylolytic Bacteria in Decayed Mangrove Stem Waste Product at Waai Seashore, Ambon Island

Mangrove （Sonneratia spp.） could be found at Waai seashore, Ambon island. The remainder of the mangrove stem will be decayed and become the waste product. Some indigenous bacteria species that live in the decayed mangrove stem waste product have cellulolytic and amylolytic characters. This research was done to： （1） identify and determine the cellulolytic bacteria species; （2） identify and determine the amylolytic bacteria species; （3） determine the cellulolytic bacteria species that have the highest cellulase activity; （4） determine the amylolytic bacteria species that have the highest amylase activity. This research was conducted at the Microbiology Laboratory, Department of Biology, State University of Malang, Microbiology Laboratory, Faculty of Medicine, Brawijaya University and Chemistry Laboratory, Muhammadiyah Malang University. In the experiment, 25 g sample were grinded and diluted in 225 mL nutrient broth to get 101 suspension. Then the suspension was diluted gradually until 101~. The suspension was inoculated on nutrient agar medium with 0.1 mL each, and incubated in 37 ~C during 24 h. Each bacteria colony was isolated and identified to know whether it was cellulolytic or amylolytic bacteria. Afterward, the cellulase activity as well as the amylase activity was analyzed. The research results show that： （1） there are four cellulolytic bacteria species, i.e., Micrococcus luteus, Bacillus pumilus, Planococcus citreus and Bacillus cereus; （2） there are four amylolytic bacteria species, i.e., Bacillus firmus, Nitrobacter sp., Bacillus mycoides and Pseudomonas aeruginosa; （3） Bacillus cereus has the highest cellulase activity; （4） Nitrobacter sp. has the highest amylase activity.

Gene Expression and Fungal Morphology in Submerged Culture Using Whole Barley of Aspergillus kawachii

The authors described a novel submerged batch culture system that produced high levels of amylase by Aspergillus kawachii using whole barley （WB）, the surface of which is covered by its husk. In this study, detailed analyses determining the amylase activities, residual sugars, fungal morphology and expression levels of genes were performed in a submerged culture using WB to address the mechanism underlying high amylase productivity in A. kawachii. High levels of glucoamylase and acid-stable u-amylase were produced in this culture, and expression levels of amylases, as well as glucose-repressive genes including high-affinity glucose transporter and peroxidase/catalase were also high. On the other hand, the morphology of mycelia was altered, with swollen, bulbous, multi-septum hyphae and conidiophores that normally form in a solid culture being partially generated. Furthermore, cell cycle and post-translational modification-related gene expression levels were altered, and were similar to those in the solid culture. These findings suggest that high amylase productivity in the submerged culture using WB is accompanied by both the up-regulation of amylase genes and activation of post-translational modifications due to fungal morphological changes being brought closer to those in the solid culture.

Screening and Preservation of Douchi Fibrinolytic Enzyme Producing Strain

[Objective] To isolate and preserve a high-activity Douchi fibrinolytic enzyme producing strain from Douchi products. [Method] The Douchi flbrinolytic enzyme producing strain was screened on the selected medium prepared with self-made pork blood powder, the strain with the highest activity was screened out according to the size of hydrolysis cycle, and then preserved in LB medium. [ Rebait] A Douchi fibrinolytic enzyme producing strain with high thrombolytic activity was successfully screened out from the Douchi produced in Hunan, Guangdong and Jiangxi Prov- inces. [ Ceadusioe] The study lays foundation for the development of new-type thrombolytic drugs.

Effects of Ionic Surfactants on Bacterial Luciferase and α-Amylase

In order to study the effects of ionic surfactants on bacterial luciferase,the cationic surfactant dodecyltrimethylammonium biomide (DTAB) and anionic surfactant sodium dodecylsulfate (SDS) were chosen.For comparison with bacterial luciferase,α-amylase was used since these two enzymes have similar electrostatic potential and charged active sites.After the enzymes were treated with the surfactants,the catalytic properties of bacterial luciferase andα-amylase were assayed,and fluorescence spectroscopy and circular dichroism (CD) were used to analyze the alteration of the protein structure.The results showed that when the DTAB concentration was low,the cationic surfactant DTAB enhanced the enzymatic activities of bacterial luciferase andα-amylase.On the other hand,the anionic surfactant SDS did not alter the enzymatic activity.The main interaction of cationic surfactant DTAB and the negatively charged surface of the proteins was the ionic interaction,which could alter the environment for the enzyme to work when the DTAB/enzyme molar ratio was low.However,at high cationic surfactant concentration,the ionic interaction and hydrophobic interaction might destroy the secondary and tertiary structures of the proteins,leading to the loss of enzymatic activities.