Comparative study of amylolytic enzymes production byAspergillus niger in liquid and solid-state cultivation

Summary Amylolytic enzymes produced by a strain ofAspergillus niger cultivated on cassava starch in liquid or solid culture were found to be mainly glucoamylases. For the same initial amount of substrate, the glucoamylase activity increased even after 60 h of culture on solid medium whereas it decreased in liquid culture. Some characteristics of the amylases produced in both culture conditions were compared. The pH optima for enzymes produced in solid and liquid cultures were 4.5 and 5.0 respectively. Glucoamylase synthetized in solid cultures was significantly more thermostable than that from liquid culture and was maximally active at 70°C compared to 50°C for the enzyme from liquid cultures. The Km values expressed as mg soluble starch/100 ml were 0.1% for crude enzyme from solid culture and 0.057% for crude enzyme from liquid culture.     

Purification and characterization of the amylolytic enzymes of Saccharomycopsis fibuligera

• 1.1. A complex of extracellular amylolytic enzymes produced by Saccharomycopsis fibuligera KZ, grown on fine fibre (waste product from corn starch production) and corn-steep liquor, has been studied.
• 2.2. α-Amylases and glucoamylases, as the main representatives of this complex, were separated by hydrophobic chromatography on Spheron 300 LC.
• 3.3. Individual isoenzymes of one type were separated on FPLC-Mono Q.
• 4.4. The relative molecular weight of α-amylases is 54,000, glucoamylases 62,000, maximal activity is reached by both enzymes between pH 5.0 and 6.2 at a temperature of 40–50°C.
• 5.5. Glucoamylases have a higher stability of the native structure than α-amylases, they retain 55% of their original activity, even after 10 min of incubation at 100°C.

     

四年间酵母样真菌感染的病原菌分布与耐药特征分析

目的了解临床酵母样真菌感染的流行特点及其耐药性,指导临床合理运用抗真菌药物。方法运用WHONET软件对中南大学湘雅三医院4年间临床分离出的酵母样真菌与其耐药进行回顾性分析。结果4年间临床酵母样真菌感染率由2002年的9.0%升至2005年的13.8%,白色念珠菌仍是引起临床感染的主要真菌,但其构成比由2002年的69.7%降至2005年的49.1%,而近平滑念珠菌的构成比4年间增加了9.5%,成为临床酵母样真菌感染的第二位病原菌。4年间临床酵母样真菌对唑类药物的耐药率增加了9.6%~16.8%。结论临床酵母样真菌引起的感染逐年增加,种类增多,对唑类药物的耐药情况日趋严重,应加强对临床真菌感染与耐药性情况的监测,以指导临床合理使用抗生素。     

Immunochemical study of surface glycoconjugates of yeast-like fungus of the Candida genus

Two complex preparations (extract I and extract II) of surface antigens were obtained from the yeast-like fungus Candida maltosa by treatment of intact cells with beta-mercaptoethylamine and pronase. Immune diffusion in agar gel revealed antigenic heterogeneity of the preparations. Both of the extracts were found to have at least 3 antigenic components. The extracts induce hypersensitivity of intact guinea pigs and candida sensitization on the 12th day after the injection of Candida maltose intact cells into the animals. The common antigen components of extracts I and II were found by means of immunochemical and chromatographic assays. The extracts preserved the antigenic activity after enzyme hydrolysis with pronase.     

药用真菌桑黄液体培养过程中的抗氧化活性研究

桑黄Sanghuangporus sanghuang是一种珍稀的药用真菌,具有较大的应用潜力。本研究主要以菌丝体生物量、多酚含量、黄酮含量、抗坏血酸(Ascorbic acid,AA)含量、总抗氧化能力(Total antioxidant capacity,T-AOC)、抑制羟自由基能力(Restraining ability to hydroxyl free radicals,RAHFR)、超氧阴离子清除能力、1,1-二苯基-2-三硝基苯肼(1,1-diphenyl-2-picrylhydrazyl,DPPH)自由基清除能力、2,2’-连氮-双(3-乙基苯并噻唑-6-磺酸)[2,2’-azino-bis(3-ethylbenzthiazoline-6-sulphonic acid),ABTS]自由基清除能力、铁离子还原能力(Ferric reducing antioxidant power,FRAP)和亚铁离子螯合能力为测定指标,对桑黄液体培养过程中的抗氧化活性进行了评价。结果显示,菌丝体生物量在2–10d内增长迅速,第10天达到最大值,在此过程中AA含量和T-AOC也出现了峰值,且多酚含量、黄酮含量和FRAP均呈上升趋势,说明菌株的抗氧化活性与其自身的生长状况、次级代谢产物分泌及还原能力等密切相关。此外,该菌株对羟自由基、超氧阴离子、DPPH自由基和ABTS自由基的清除能力也较强,于第12天、第10天、第2天和第14天分别达到73.06U/m L、46.78%、86.47%和94.16%,显示了较强的抗氧化活性。较高的亚铁离子螯合能力也说明桑黄在氧化胁迫下可启动自身的抗氧化系统以阻断自由基链反应。研究结果为更好地研究、开发和利用药用真菌桑黄提供了基础资料。     

Biosynthesis of hydrolytic enzymes during cocultivation of macro- and micromycetes

Effects of co-cultivation of higher Basidiomycetes and Phycomycetes on the biosynthesis of cellulases, amylases, and proteases was studied. Four optimal pairs of fungal cultures were selected. Of these, three pairs belonged to higher fungi, and one pair was constituted by fungi of distinct ecological groups, a macromycete and a micromycete. The activities of amylase and protease were 1.5 to 2 times higher, and the activity of cellulase was lower during the growth of higher fungi associations. The mixed association of the macromycete Schizophyllum commune and the micromycete Mucor sp. was the most active producer of hydrolytic enzymes. During the growth of this mixed association, a fourfold and 1.5-fold increases were observed in the activity of endoglucanase and protease, respectively, paralleled by stimulation of amylase formation.     

Biosynthesis of high concentrations of an exopolysaccharide during the cultivation of the microalgaBotryococcus braunii

Summary A non-axenic strain of the microalgaBotryococcus braunii Kützing, isolated from a small lake in Portugal, when cultured at 25°C in mineral medium and under continuous illumination, showed a poor production of hydrocarbons (5% of the dry biomass) but excreted remarkably high quantities of an exopolysaccharide (4–4.5g/l) into the medium. The production of soluble polysaccharide with galactose, fucose and uronic acid residues, follows growth. The role of the mucoid contaminating bacteria in polysaccharide production in the mixed culture was unproven.     

Biosynthesis of fumiquinazolines by the fungus Penicillium thymicola

Biosynthesis of fumiquinazolines F and G (FQs), PC-2, and pigments by the fungus P. thymicola VKM FW-869 is directly dependent on the content of carbon substrate (mannitol) in the medium. Pigment production prevailed at all of the tested mannitol concentrations. The necessary conditions for predominant FQ biosynthesis by the fungus P. thymicola are carbon source (mannitol) limitation and presence of NaCl in the cultivation medium. NaCl has a regulatory effect on the formation of secondary metabolites by enhancing FQ biosynthesis and reducing pigment formation. The maximum values of FQ biosynthesis and inhibition of pigment production are obtained at a mannitol concentration of 20 g/l and 2.5% NaCl in the medium.     

Biosynthesis of fumiquinazolines by the fungus Penicillium thymicola

Biosynthesis of fumiquinazolines F and G (FQs), PC-2, and pigments by the fungus P. thymicola VKM FW-869 is directly dependent on the content of carbon substrate (mannitol) in the medium. Pigment production prevailed at all of the tested mannitol concentrations. The necessary conditions for predominant FQ biosynthesis by the fungus P. thymicola are carbon source (mannitol) limitation and presence of NaCl in the cultivation medium. NaCl has a regulatory effect on the formation of secondary metabolites by enhancing FQ biosynthesis and reducing pigment formation. The maximum values of FQ biosynthesis and inhibition of pigment production are obtained at a mannitol concentration of 20 g/l and 2.5% NaCl in the medium.     

Effect of cultivation temperature on thermal stability of lipolytic enzymes of the fungus Rhizopus microsporus, UzLT-1

The yield, activity and thermal stability of lipolytic enzymes obtained from the culture fluid filtrates of Rhizopus microsporus, UzLT-1, cultivated at 28, 38 and 48 degrees C (preparations I, II and III, respectively) were investigated. Maximal lipolytic activity was found in Prepartion II, and maximal yield and thermal stability in Preparation III. By disc electrophoresis and DEAE-cellulose chromatography, the presence of three lipolytically active enzymes in the preparations was demonstrated.