L—苹果酸产生菌Aspergillus flavus HLD—12产酸条件的研究

本文报道ＨＬＤ－１２菌株发酵Ｌ－苹果酸的特点．研究了碳源、氮源、温度、ＣａＣＯ３、金属离子和促进剂等因素对ＨＬＤ－１２菌株苹果酸发酵的影响，确定了ＨＬＤ－１２菌株的最佳产酸条件，其中最适碳源为８％的葡萄糖，最适氮源为０．１５％的（ＮＨ４）２ＳＯ４，ＣａＣＯ３浓度为７％。生物素和丙氨酸在一定浓度范围内能显著提高ＨＬＤ－１２菌株的产酸水平。     

Biological control of aflatoxin contamination of crops

Aflatoxins produced primarily by two closely related fungi, Aspergillus flavus and Aspergillus parasiticus, are mutagenic and carcinogenic in animals and humans. Of many approaches investigated to manage aflatoxin contamination, biological control method has shown great promise. Numerous organisms, including bacteria, yeasts and nontoxigenic fungal strains of A.flavus and A. parasiticus, have been tested for their ability in controlling aflatoxin contamination. Great successes in reducing aflatoxin contamination have been achieved by application of nontoxigenic strains of A. flavus and A. parasiticus in fields of cotton, peanut, maize and pistachio. The nontoxigenic strains applied to soil occupy the same niches as the natural occurring toxigenic strains. They, therefore, are capable of competing and displacing toxigenic strains. In this paper, we review recent development in biological control of aflatoxin contamination.     

梁料脱色菌—无花果曲霉（Aspergillus ficuum）的紫外诱变育种

染料脱色菌无花果曲霉（Aspergillus ficuum）经紫外线诱变后，筛选出变株P11在33℃、120r／min振荡培养条件下，3d内以对染料直接耐酸大红4BS的脱色率为88．54％比出发菌株提高了13％，经斜面传代10次，脱色能力保持稳定。     

松墨天牛致病菌葡萄曲霉安全性研究

松墨天牛生葡萄曲霉Aspergillus vitis分生孢子对水蚤、果蝇、鲤鱼和对小白鼠经口、经皮、吸入急性毒性试验结果表明：水蚤在20mg／L浓度下72h死亡率23.3％;果蝇在浓度为21mg／L下72h死亡率15．0％;鲤鱼在浓度为22mg／L时72h死亡率4．0％。用3种途径对小鼠的试验表明,小鼠无死亡现象发生,小鼠的体重也无明显影响。该葡萄曲霉对这些实验动物表现为低毒或微毒。     

海洋烟曲霉菌代谢活性物质的萃取

以海洋烟曲霉菌为出发菌,在适宜的发酵条件下进行培养,提取代谢产物并检测其对白色念珠菌抑菌性.分别以硫酸铵、石油醚、乙酸乙酯为萃取剂,研究硫酸铵质量分数和有机溶剂的pH值对海洋烟曲霉菌代谢活性物质萃取效果的影响.结果表明,粗酶液的适宜萃取条件:萃取剂为石油醚,pH值为6,粗酶液与有机溶剂的体积比为1∶1.采用质量分数为70%的硫酸铵沉淀,萃取活性物质的酶活性最大为16.0μkat.L-1,比原粗酶液的酶活(7.9μkat.L-1)提高1倍;而采用石油醚为萃取剂,所萃取活性物质的酶活性最大为20.5μkat.L-1,比原粗酶液的酶活提高2.58倍,且抑菌性能最好,抑菌率达60%左右.     

Aspergillus usamii B_1-12果胶酶合成诱导的初步研究

A.usamii B_1-12果胶酶的合成受果胶类物质的诱导,不同诱导物诱导效果不同,同一诱导物在不同pH条件下诱导作用也有差别。桔子果胶脱酯化处理后,诱导作用降低,说明一定程度的甲酯化对诱导作用是有利的。用一定量果胶酶酶解桔子果胶可提高它的诱导效果,表明果胶降解后的中间产物或代谢物也是有效的诱导物。据此,本文对A.usamii B_1-12果胶酶合成诱导作用的机制提出了一种可能的解释。     

Fungal competition and mycotoxin production on corn

Summary Aflatoxin and secalonic acid D production in corn in laboratory and field by mixed cultures ofPencillium oxalicum andAspergillus flavus orA. parasiticus was lower than production by the pure cultures. However, mixed culture of these molds withFusarium spp. did not affect mycotoxin production.     

Research on Pectase Secreted by Aspergillus Niger Degumming Kenaf Bast Fiber

In this paper, the aerobic metabolism mechanism of Aspergillus Niger （AS 3.3 50 ）, which is the most suitable bacteria for degumming kenaf fiber, is expounded, and macromolecular structure of pectin is also analyzed. The fracture position of the macromolecular chain of kenaf pectin and its outgrowth structure, affected by Endo-PG and Exo-PG are secreted by AS 3. 350 and explored in molecule scale. The optimal value of degumming parameters are fixed： temperature 34 - 36℃, time 48 - 50 h, pH 6.5 - 7.5. Compared with kenaf fibers obtained by natural method, the ones deguntmed by bio-enzymatic method possess of smoother surface, .better. Separation, less impairment and higher strength with. residual pectin percentage of 14.5 %.     

两种重组真菌植酸酶的纯化及其酶学性质比较

对相同表达系统中产生的黑曲霉植酸酶(r-Anp)与烟曲霉植酸酶(r-Afp)的酶学特性进行了比较.两者的Km值都较低,但r-Anp的Vmax值远高于r-Afp（102.5 vs. 29.5 μmol·mg-1·min-1,P＜0.05）.r-Anp在pH 2.5仍具有植酸酶活力,而r-Afp则丧失全部活性.差示扫描量热法(DSC)研究发现r-Afp的蛋白质解链温度（Tm）低于r-Anp（59.1 ℃ vs. 62.1 ℃),但经热处理（90 ℃,20 min）后,前者残余更多的相对酶活（81% vs. 3