壳聚糖絮凝纯化香菇多糖的研究

研究了壳聚糖对香菇多糖提取液的沉降作用,考察了壳聚糖用量、沉降时间、溶液酸度对吸附色素、沉降蛋白质和多糖损失的影响,同时考察了壳聚糖对超滤膜分离初始膜通量的影响。实验结果表明壳聚糖对香菇多糖提取液中色素和蛋白质具有较好的絮凝沉降效果,当壳聚糖的用量为5.0mg/mL,絮凝沉降时间为40min,溶液pH为5.0时,60r/min的转速搅拌条件下,色素含量降低了约28%,蛋白质含量降低了42%左右,而多糖含量只损失8.9%左右,溶液粘度降低了11.8%,采用超滤分离时,经壳聚糖沉降的多糖溶液初始膜通量增加了14%左右。     

壳聚糖絮凝法精制合欢皮多糖水提液的工艺

采用壳聚糖对合欢皮总多糖的絮凝纯化工艺进行研究。通过单因素和正交试验,得到优化的工艺条件:壳聚糖用量为生药量0.8 mL/g,絮凝温度35℃,絮凝时间4 h,药液浓缩比(质量体积比)为1∶10(g/mL),在此条件下,多糖保留率、脱蛋白率和多糖纯度分别为91.23%、22.26%和47.27%,优于传统的水提醇沉法。     

壳聚糖絮凝蛹虫草菌丝体多糖工艺优化及其失活动力学分析

利用响应面法对蛹虫草诱变菌株CSYB-2菌丝体多糖的制备工艺进行优化,结果显示在壳聚糖用量1.4mL/g、絮凝温度55℃、絮凝时间70min条件下,多糖保留率为(82.05±0.21)%。在壳聚糖絮凝诱变菌株CSYB-2菌丝体多糖浸提液的絮凝工艺基础上,通过构建壳聚糖失活动力学模型,探究絮凝剂（壳聚糖）在絮凝过程中的动力学规律和失活机理。结果表明壳聚糖的失活动力学符合一级反应的失活动力学方程,在考察溶液澄清率（絮凝率）在不同时间、温度下变化规律的基础上推算出失活速率常数、活化能等动力学函数值,为研究絮凝作用中絮凝剂失活的机理提供理论支持。     

壳聚糖对嘧啶核苷类新型抗真菌抗生素发酵液絮凝除菌作用的研究

利用天然高分子聚合物壳聚糖为絮凝剂去除抗生素发酵液中的菌体,结果表明:发酵液pH值、絮凝剂用量是影响絮凝效果的主要因素。最佳絮凝条件为pH7.0,絮凝剂用量0.4g/L,温度30℃,此时菌体絮凝率(FR%)可达70%以上。经絮凝预处理后,滤速为处理前的2.5倍,发酵液的效价由700 U/mL提高到860 U/mL。     

聚丙烯酸分离纯化苦瓜种仁碱性蛋白的方法及影响因素

以苦瓜籽为材料,研究了聚丙烯酸分离纯化苦瓜种仁碱性蛋白的方法及影响因素。等电点沉淀试验表明,柠檬酸、盐酸分别调节苦瓜种仁粗提液pH至6.0、4.0时,各有14.62%和32.49%的苦瓜种仁蛋白被沉淀。醋酸的等电点沉淀作用呈现阶段性特点,pH6.0和4.0时分别有26.17%和38.72%的苦瓜种仁蛋白被沉淀。醋酸、盐酸和柠檬酸处理的1mL苦瓜种仁粗提液(pH4.0),1%PAA选择性沉淀碱性蛋白(等电点pI为8.65~9.30)的最佳用量分别为100μL、120μL和100μL。醋酸调节苦瓜种仁粗提液pH分别至5.0、4.0和3.0,等电点沉淀后的上清液用PAA沉淀碱性蛋白,当PAA(1%)用量为160μL/mL提取液时,pH5.0和3.0样液分别有33.77%和43.56%蛋白质被沉淀;当PAA用量为120μL/mL提取液时,pH4.0样液中30.83%蛋白质被沉淀。PAA-蛋白质复合物溶解于碱性溶液(pH>9.0),当溶液NaCl浓度为3.0%时,溶液蛋白质浓度最高。PAA选择性沉淀的苦瓜种仁碱性蛋白经SephadexG-75柱层析分离,分别在175min和300min出现主峰Ⅰ和Ⅱ。SDS-PAGE和IEF分析表明主峰Ⅰ的分子量约为30kD,pI值约为9.5,主峰Ⅱ的分子量约为10kD,pI值约为9.3。     

美味牛肝菌多糖最佳提取工艺研究

对美味牛肝菌 (BoletusedulisBull)子实体多糖提取最佳工艺条件进行了研究。通过实验既探讨了温度、pH值、时间、料液比及浸提级数对提取效果的影响 ,也探讨了酶法、三氯乙酸—正丁醇法及复合法去除蛋白的工艺条件。结果表明 :蛋白质去除最佳工艺为酶法和三氯乙酸—正丁醇复合法 ,美味牛肝菌多糖提取最佳工艺为加水 2 0倍 ,80℃ ,pH 8时浸提 1h ,多糖浸提率可达 7.37%。     

响应面分析法优化超声波辅助酶法提取南五味子多糖工艺的研究

为了建立超声波辅助酶法提取南五味子多糖的方法,并研究其提取工艺。按照Box-Benhnken中心组合试验设计原理,以多糖得率为响应值,以单因素实验数据为基础,进行响应面分析实验,考察提取pH、提取温度和提取时间对多糖得率的影响。结果显示：最佳提取工艺条件为：提取pH为4.8、提取温度57℃、提取时间66 min、复合酶用量为3.0%,最佳工艺条件下南五味子多糖得率为8.73%±0.25%。研究结果表明,该提取方法可减少多糖提取时间和提取溶剂用量,降低温度,有效提高了多糖的提取得率,可应用于南五味子多糖的制备。研究结果为南五味子多糖的开发应用提供了较好的依据。     

磁性羧甲基壳聚糖微球结构及性能表征及其用于造纸废水处理研究

采用反相悬浮法制备改性壳聚糖磁性微粒絮凝剂,并探讨了该絮凝剂对造纸废水的絮凝作用,着重考察了絮凝剂的投入量、体系pH值、搅拌速度、搅拌时间、沉降时间对造纸废水中COD去除率的影响。结果表明在最佳条件下该絮凝剂对造纸废水的COD去除率可达56.52%,且具有投入量少、pH应用范围广、絮凝时间和沉降时间短的优点,说明改性壳聚糖磁性微粒作为絮凝剂对造纸废水的处理切实可行。     

葡萄皮色素提取条件的综合研究

利用葡萄饮料厂生产加工的废料葡萄皮提取天然色素,并对影响色素提取率的因素如:提取溶剂的选择、提取剂用量、提取温度、提取时间及提取pH等条件进行研究,初步确定获得最大提取收率的条件,即:以无水乙醇为提取剂,葡萄皮重(g)与提取剂的用量(mL)之比为1 7,提取温度60~80℃,时间为70min,pH为2~4。同时对提取次数进行了研究,结果表明提取2次较好。     

甘灵茶抗氧化成分的提取工艺研究

为了开发甘灵茶的应用价值,采用DPPH法对甘灵茶提取液的抗氧化性进行了研究。以提取液清除DPPH的效果为评价指标,采用单因素试验和正交试验,研究了甘灵茶的提取温度、pH值、提取时间、甘灵茶用量对抗氧化物质提取效果的影响,获得了提取的最佳工艺参数。结果显示：提取甘灵茶抗氧化物质的最优水平组合为提取温度为60℃、溶剂pH值为8.5、提取时间为15min、甘灵茶用量为3%,此条件下DPPH清除率为86.24%,多酚含量为0.187mg/mL,多糖含量为0.244mg/mL。     

Effective biomass harvesting of marine diatom Chaetoceros muelleri by chitosan-induced flocculation,preservation of biomass,and recycling of culture medium for aquaculture feed application

Microalgae are a promising new source of biomass; however, large-scale economical harvesting of microalgal biomass is a major technological and economic challenge, limiting the commercial production of microalgal biomass for high-value compounds. In this study, the cationic polymer chitosan was used for the harvesting of the marine diatom Chaetoceros muelleri. Natural flocculation, and pH and chitosan-induced flocculation were studied in detail. The effects of flocculant dosage, culture pH, initial biomass concentration, and sedimentation time were investigated on biomass recovery. The results showed that flocculation efficiency can reach > 99% with an optimum dosage of chitosan (80 mg L^?1) at pH 9.6 and settling time of 40 minutes for biomass concentration from 0.2 to 1.2 g L^?1. The reusability of the recycled water, preservation of biomass after harvesting, and cost of the harvesting process were evaluated. The results showed that the chitosan-induced flocculation offers an efficient, cost-effective, rapid, and sustainable harvesting method for C. muelleri biomass for food and feed applications in aquaculture.

     

Harvesting of microalgae using flocculation combined with dissolved air flotation

This study explored efficient methods of harvesting the Tetraselmis sp. KCTC12236BP using flocculation and dissolved air flotation. Concentration ranges of flocculation agents were optimized using jar tests (batch flocculation experiments) using inorganic (aluminum sulfate, ferric sulfate) and organic (chitosan) flocculants in a pH range of 4 ～ 10. The optimal dosage and pH level were 1.2 g/L and pH 5 ～ 6 for aluminum sulfate, 0.7 g/L and pH 4 ～ 8 for ferric sulfate, and 5.0 mg/mL and pH 7 ～ 8 for chitosan. The highest harvesting efficiency achieved with each of the four compounds was 85.6, 92.6, 93, and 91.3%, respectively.     

Harvesting the microalgae Phaeodactylum tricornutum with polyaluminum chloride, aluminium sulphate, chitosan and alkalinity-induced flocculation

The purpose of this study was to explore efficient methods of harvesting the microalga Phaeodactylum tricornutum. Natural sedimentation experiments, performed at different light and temperature conditions, did not yield significant improvements in efficiency even after 1?week. When alkalinity-induced flocculation was performed, both the flocculation efficiency and the concentration factor dramatically improved at pH?=?9.75 (0.5–0.7 units over the original pH of the culture) after 10?min settling time. Sedimentation rates are documented at pH ranging between pH?9.75 and 11.0. The results of the application of two conventional flocculants used in wastewater treatment, polyaluminium chloride and aluminium sulphate, are also presented. Chitosan was also used as a natural flocculating agent to improve possible contamination problems in the downstream process. pH was adjusted in order to determine optimum flocculation efficiency of chitosan in combination with a high concentration factor. Satisfactory results were found with chitosan at an adjusted pH of 9.9 using concentrations as low as 20?mg?L^?1, after testing a flocculant range of 5–200?mg?L^?1.     

Recovery of protein from discharged wastewater during the production of chitin

Studies were carried out to optimize the conditions for the recovery of protein. The results showed that pH of 6.00 for wastewater, the dosage of 1% chitosan solution in 1% acetic acid aqueous solution of 2.0 ml for 50 ml wastewater and 1% FeCl(3) aqueous solution of 2 ml for 5 0ml wastewater, the flocculation time of 4.0 h were the optimal conditions for the recovery of protein. The obtained protein sediment contained abundant amino acids, especially isoleucine, methione and lysine that are absent in other protein resource.     

Selective flocculation with chitosan in Escherichia coli disintegrates: effects of pH and nuclease treatment.

The flocculation of cell debris from a beta-galactosidase constitutive E. coli with chitosan as a flocculant was studied to investigate the possibility of obtaining a selective flocculation in cell disintegrates with high product recoveries. The flocculation removed 98% of the cell debris by 30 min sedimentation under gravity, which should be compared to a separation of the cell debris without flocculation of only 70% by centrifugation at 15,000 g. Optimal flocculation dosages varied between 12 and 43 mg chitosan g-1 dry weight of cells, depending on pH. The yield of the product beta-galactosidase reached 60% at optimal pH. Hydrolysis of the nucleic acids by DNAase and RNAase decreased the optimal flocculation dosages considerably. The study showed that the flocculation is somewhat selective, since chitosan also removed 85% of the nucleic acids and 50% of the proteins, which contributed to the purification of the protein solution.     

Flocculation performance of a cationic biopolymer derived from a cellulosic source in mild aqueous solution

The flocculation behavior of cationic, quaternary ammonium groups containing cellulosic biopolymers, CDACs, synthesized by cationizing dialdehyde cellulose in mild aqueous solution was studied in a kaolin suspension. In particular, the role of CDAC dosage and solution pH, NaCl concentration, and temperature were clarified. In addition, the initial apparent charge densities (CDs), particle sizes, ζ-potential, and stability of CDs were determined. CDACs possessed a high flocculation activity in neutral and acidic solutions, but a significant decrease was observed in alkaline solutions (pH >9). This was also seen as a decline in the apparent CD and particle size of the CDACs in alkaline conditions. The measurements also indicated that the apparent CD decreased to a constant level of 3 mmol/g in aqueous solutions. However, no notable decrease in flocculation performance was obtained after several days of storage. Moreover, the variation of NaCl concentration and temperature did not affect the flocculation activity.     

The impact of cell wall carbohydrate composition on the chitosan flocculation of Chlorella

The carbohydrate composition of the algal cell wall was investigated for its role in cell flocculation. Cultures of Chlorella variabilis NC64A, which were found to have different levels of neutral sugar, uronic acid and amino sugar in the cell wall when cultured in different nitrogen sources and concentrations, were subjected to flocculation with chitosan at dosages of 0–69.6 mg/l and pH values of 5.5, 7 and 8.5. In addition, flocculations of another three strains of Chlorella, which have different levels of cell wall components, were tested. Flocculation improved for all strains at pH 8.5 suggesting that inter molecular forces such as hydrogen bonding might be more important than charge neutralization in the flocculation of Chlorella. Total carbohydrate content in the cell wall was the most significant factor positively affecting the flocculation efficiency of C. variabilis NC64A cells with different cell wall compositions and the other Chlorella strains. The results presented in this study suggest that chitosan flocculation can be improved by optimizing the cell culture conditions to achieve higher cell wall polysaccharide content or selecting an algal strain with higher cell wall polysaccharide content.