产朊假丝酵母处理马铃薯淀粉废水

研究了pH、接种量、无机盐(通过加入磷酸二氢钾进行无机盐补充)及DO等对产朊假丝酵母处理马铃薯淀粉废水的影响.结果表明.在pH为5.0、产朊假丝酵母接种量为10%(体积分数)、磷酸二氢钾(质量分散为0.1%)加入量为0.5 g/L、废水不灭菌的条件下,废水处理效果和产朊假丝酵母生长最佳.且当废水COD为5 074 mg/L时,COD去除率达到74.86%,同时可获得2.23g/L的单细胞蛋白.产朊假丝酵母处理马铃薯淀粉废水的最佳条件的实验研究对实现马铃薯淀粉废水资源化利用提供了理论参考.     

Supramolecular complex formation,a possible antigenotoxic mechanism of glucomannan against aflatoxin B1

Abstract

Glucomannan is a highly branched polysaccharide with glycosidic linkages, constituted of mannoses and glucoses. In recent years, its usefulness due to its immunological, antioxidant and antimutagenic activity has been recognized. The aim of the study was to determine the antigenotoxic ability of glucomannan extracted from Candida utilis orally administered (100–700?mg/kg) to mice, which subsequently received 1?mg/kg aflatoxin B₁. Hepatocytes obtained from these animals 4–16?h post administration were examined by means of the comet assay. The antigenotoxic effect was found to be higher than that observed in previous studies with α-mannan and β-D-glucan isolated from Saccharomyces cerevisiae., In order to explore the possibility of formation of a supramolecular complex between glucomannan and aflatoxin B₁, both compounds were co-crystallized, their melting points determined, and the complex analyzed through ultraviolet spectroscopy. The spectroscopy data suggest that the protective effect of glucomannan is related to the formation of a supramolecular complex between the two compounds.     

Biosorption effects of copper ions on Candida utilis under negative pressure cavitation

Under the optimal condition of copper ions adsorption on yeast,we found some different effects among static adsorption, shaking adsorption and negative pressure cavitation adsorption, and the methods of yeast with different pretreatments also affect adsorption of copper ions. At the same time, the change of intercellular pH before and after adsorption of copper with BCECF was studied. The copper distribution was located by using PhenGreen （dipotassium salt and diacetate）, and the surface of yeast was observed by an atomic force microscope. The results showed that negative pressure cavitation can improve bioadsorption capacity of copper ions on yeast. However, the yeasts＇ pretreatment has a higher effect on bioadsorption. It indicates that heavy metal bioadsorption on yeast has much relation with its cellular molecule basis. With the adsorping, the intercellular pH of yeast increased gradually and changed from acidity to alkalescence. These results may suggest that negative pressure cavitation can compel heavy metals to transfer from the cell surface into inside cell and make the surface of yeast coarse.     

流加发酵及添加L-半胱氨酸对产朊假丝酵母高密度培养合成谷胱甘肽的影响

通过7L罐考察了不同葡萄糖流加速率以及添加L-半胱氨酸对产朊假丝酵母(Candida utilis)WSH02-08高密度发酵生产谷胱甘肽(GSH)的影响.结果表明,在恒定速度(5.5g L-1h-1)流加葡萄糖30h的基础上,发酵45h后细胞干重最高达到73g L-1,此时向发酵罐中一次性添加L-半胱氨酸40mmol L-1,最终GSH产量和胞内GSH含量分别达到了1458mg L-1和2.26%.图4表1参11     

产朊假丝酵母生物吸附Cu2+影响因素及吸附机理的研究

选取产朊假丝酵母作为生物吸附材料,在确立Cu2 最佳吸附条件的基础上,通过细胞内pH值荧光探测剂测定酵母吸附重金属前后的pH值变化,以及运用phengreen细胞内外重金属荧光探测剂进行重金属分布定位,对酵母生物吸附的机理进行了初步的探讨.实验结果表明,最佳吸附条件为PH 4.49～5.04,[酵母]:[Cu2 ]为60:1;酵母细胞内pH值随吸附时间的增加而有所升高,并由酸性变为弱碱性,与此同时酵母死亡率也随吸附时间的增加而迅速增加;生物吸附主要集中在细胞壁的结合位点上,在细胞内部基本没有;生物吸附过程分为2个步骤,首先是一个快速过程,然后是一个慢速过程,但吸附中出现的慢速过程并不一定代表重金属由细胞外进入细胞内.     

Stoichiometric characteristics of nitrogen and phosphorus in Chimonobambusa utilis leaves at different elevations北大核心CSCD

海拔对植物养分元素的分配和生存策略的权衡具有重要影响.为了解金佛山方竹(Chimonobambusa utilis)叶片氮、磷养分对海拔梯度的响应,以四川盆地南缘3个海拔(1 400 m、1 600 m和1 800 m)金佛山方竹纯林为研究对象,建立12个典型样地,对生长季节叶片氮、磷含量和土壤养分含量、温度、含水量等进行定量研究和相关性分析.结果表明:(1)随海拔的升高,叶片氮含量呈上升趋势,叶片磷含量呈下降趋势,叶片氮磷比呈上升趋势;各海拔叶片氮磷比均大于16,表明金佛山方竹生长可能受到磷限制.(2)冗余分析表明,叶片氮含量和氮磷比与土壤温度、含水量和速效磷含量呈负相关,与土壤速效氮含量呈正相关;叶片磷含量与土壤全氮和速效氮含量呈负相关,与其余环境因子呈正相关;土壤温度、速效氮、全氮、含水量和速效磷含量对叶片氮、磷化学计量特征整体影响显著,变量解释度分别为72.10%、7.90%、8.80%、2.50%和1.20%.(3)相对重要性分析表明,土壤温度和速效氮含量是叶片氮含量变异的主导因子,土壤温度、速效磷和全氮含量是叶片磷含量变异的主导因子,土壤温度、速效磷含量和速效氮含量是叶片氮磷比变异的主导因子.上述研究结果说明,海拔引起的土壤温度和养分供应的差异调节着金佛山方竹叶片的氮、磷化学计量特征.(图4表3参49)     

产朊假丝酵母CANDIDA UTILIS细胞壁对铜离子吸附位点的研究

目前认为所有生物大分子都对重金属离子有较强吸附性 ,但某些分子可特异地吸附重金属 ,并介导酵母细胞对重金属的抗性[1] .其中细胞表面的高分子聚合物倍受关注 ,酵母细胞壁约含 4 0种蛋白分子 ,但有关这些蛋白质在对重金属离子吸附中的作用目前还未见报道 .产朊假丝酵母Ｃａｎｄｉｄａｕｔｉｌｉｓ是重要单细胞蛋白生产菌株之一 ,因其营养条件要求不高 ,对工业废水有较强耐受和转化能力而广泛用于生产和研究 .我们观察了产朊假丝酵母细胞与分离纯化的细胞壁对铜离子的吸附能力差异 ,并对细胞壁上重金属离子吸附位点进行了研究 .1　材料与方…     

Candida utilis生物合成谷胱甘肽的营养及环境条件

研究了摇瓶条件下Candida utilis WSH02—08生物合成谷胱甘肽(GSH)的营养条件，确定以葡萄糖作为碳源，硫酸铵和尿素作为混合氮源．在L6(4^5)正交试验的基础上，选用BP神经网络对营养条件进行优化和预测，得出较优的营养组合为：葡萄糖30gL^-1(NH4)2SO4gL^-1，尿素4gL^-1，KH2PO4 3gL^-1，MgSO4 0．25gL^-1．研究了GSH发酵的环境条件，得出较优的组合为：初始pH6．0，装液量30mL／250mL，接种量10％．利用优化后的营养及环境条件进行摇瓶发酵实验，结果表明，GSH产量和细胞干重均有较大幅度的提高．图7表2参13