冬虫夏草菌发酵溶氧条件的优化

目的:优化冬虫夏草菌发酵的溶氧条件。方法:在5 L机械搅拌发酵罐中培养冬虫夏草菌,以菌丝得率为响应值,对影响供氧的主要因素进行Box-Behnken响应面法优化,并对4种圆盘涡轮的搅拌效果进行对比。结果:最佳溶氧条件为:搅拌转速370 r/min,通气量6.5 L/min,罐压0.03 MPa;在此条件下虫草菌丝得率为9.21 g/L。4种圆盘涡轮促进供氧的顺序为:箭叶>斜直叶>弯叶>平直叶,以箭叶圆盘涡轮在响应面优化后的条件下发酵虫草菌丝得率最高,达9.65 g/L。结论:响应面法能较好地预测试验结果,优化后的条件更利于菌丝生长。

海鞘桔青霉Asc2-4培养基和溶氧条件优化对产油性能的影响

【目的】优化海鞘(Pyrosomella verticilliata)桔青霉(Penicillium citrinum)Asc2-4培养基和溶氧条件,以提高其生物量和产油率。【方法】采用单因素法优化培养基碳氮源及碳氮源比,通过正交试验优化无机盐,采用组合法优化溶氧条件,通过干质量法、酸热提油法及气相色谱法评价优化结果。【结果】经培养基优化,确定碳源为葡萄糖,葡萄糖质量浓度为100g/L,氮源种类为蛋白胨+酵母膏(1∶1),碳氮比为100,无机盐配比为KH2PO44 g/L、MgSO4150 mg/L、FeCl330.0μg/L;溶氧组合优化条件为转速220 r/min,250 mL锥形瓶装液量100m L。最终生物量和油脂质量浓度分别提高至19.90、8.76g/L,比未优化前约提高1.5倍和20倍;发酵油的不饱和脂肪酸质量分数达53.37%,其中油酸和亚油酸皆达到26%以上。【结论】优化后菌株的产油性能大幅提高,该菌有作为生产油酸和亚油酸的工业菌种潜力。

Solubility of Piperine in Supercritical and Near Critical Carbon Dioxide

Piperine is a member of the lipids family commonly found in peppercorn, ginger and other natural sources and is grouped as an alkaloid. The solubility of piperine has been determined in carbon dioxide at near critical and supercritical conditions in a dynamic extraction apparatus. The conditions studied were at pressures ranging from 10 to 20 MPa and temperatures at 293, 300, 313, 323 and 333 K. The results showed that piperine solubility increased with increasing pressure at all temperatures studied. The solubility of plperme in near critical conditions was slightly higher than that at supercritical conditions only at the low-pressure range. Two semi-empirical density dependent correlations, namely the Chrastil model and the Dilute Solution model, were also used to estimate the solubility data. Although both models showed good correlation with the solubility data, the Dilute Solution model performed better prediction than the Chrastil model.

Oxidation of Lingwu Coal Extraction Residue in Aqueous Sodium Hypochlorite under Mild Conditions

To investigate the structural features and provide an alternative method for high value-added utilization of coal, Lingwu coal was first extracted with organic solvent at room temperature. Then its extraction residue was oxidized in aqueous sodium hypochlorite(ASHC) under mild conditions. The effects of oxidation conditions, such as temperature, reaction time, the ratio of Lingwu coal extraction residue(LCER, g) to ASHC(m L) and p H value, on the product distributions and compositions were investigated. The results of gas chromatography/mass spectrometry(GC/MS) suggested that 53 kinds of methyl esterified products were detected in total, and benzene carboxylic acids were the main oxidation products, while chloro-substituted benzene carboxylic acids were the main by-products. Higher yield and fewer kinds of organic acids could be obtained at lower p H value, especially for the main objective product, benzene carboxylic acids.

Zinc Redistribution in a Soil Developed from Limestone During Pedogenesis

The long-term redistribution of Zn in a naturally Zn-enriched soil during pedogenesis was quantified based on mass balance calculations. According to their fate, parent limestones comprised three Zn pools: bound to calcite and pyritesphalerite grains, bound to phyllosilicates and bound to goethite in the inherited phosphate nodules. Four pedological processes, i.e., carbonate dissolution, two stages of redox processes and eluviation, redistributed Zn during pedogenesis. The carbonate dissolution of limestones released Zn bound to calcite into soil solution. Due to residual enrichment, Zn concentrations in the soil are higher than those in parent limestones. Birnessite, ferrihydrite and goethite dispersed in soil horizon trapped high quantities of Zn during their formation. Afterwards, primary redox conditions induced the release of Zn and Fe into soil solution, and the subsequent individualization of Fe and Mn into Zn-rich concretions. Both processes and subsequent aging of the concretions formed induced significant exportation of Zn through the bottom water table. Secondary redox conditions promoted the weathering of Fe and Mn oxides in cements and concretions. This process caused other losses of Zn through lateral exportation in an upper water table. Concomitantly, eluviation occurred at the top of the solum. The lateral exportation of eluviated minerals through the upper water table limited illuviation. Eluviation was also responsible for Zn loss, but this Zn bound to phyllosilicates was not bioavailable.

Influence of Solvent Polarity and Conditions on Extraction of Antioxidant, Flavonoids and Phenolic Content from A verrhoa bilimbi

This paper presents the influence of solvent polarity and extraction conditions on the extraction of total flavonoid, total phenolic and antioxidants from Averrhoa bilimbi. The experiment was performed using a different solvent at different extraction conditions, including extraction time （15-240 min）, temperature （30-70 ℃） and agitation speed （50-300 rpm）. Results showed that yields of extraction varies with solvent polarity. Extraction using 50% aqueous methanol gives the highest antioxidant activity and flavonoid content. The highest total flavonoid content （193.3 μg quercetin equivalent/g dry weight）, total phenolic content （717.8 μg gallic acid equivalent/g dry weight） and antioxidant activity （77%） was achieved using 50% methanol, at 70 ℃ and agitation speed of 300 rpm. This work may be useful for obtaining higher bioactive compounds during the extraction process of A. bilimbi.