一株产聚乙烯醇降解酶的紫色杆菌的发酵条件研究

从聚乙烯醇(PVA)污染环境中筛选出一株产聚乙烯醇降解酶活力较高的菌株WSH04-01,该菌株能够利用聚乙烯醇作为唯一碳源进行生长.通过一系列生理生化试验和16S rDNA序列分析结果,鉴定该菌株属于紫色杆菌属(Janthinobacterium sp.),实验室编号WSH04-01.这是目前国内外有关紫色杆菌产生PVA降解酶的首例报道.首先对菌株合成PVA降解酶的营养条件进行了考察,通过单因素试验和正交试验确定了菌株最优培养条件为PVA10 g·L-1,葡萄糖3 g·L-1,酵母膏6 g·L-1,K2HPO4 2 g·L-1,KH2PO4 0 25 g·L-1,MgSO4 0.05 g·L-1,CaCl2 0.05 g·L-1,FeSO4·7H2O0.02 g·L-1,NaCl 0.02 g·L-1.最适发酵温度为30℃,培养基初始pH为7.2,装液量为30 mL培养基(250mL摇瓶)-1,接种量为8%.在最优条件下,PVA降解酶酶活可以达到4.94 U·mL-1,略高于正交试验中的最高酶活(4.83 U·mL-1).同时利用凝胶渗透色谱得到分子量分布图,对最优发酵条件下发酵过程中聚乙烯醇的降解进行了验证.     

聚乙烯醇降解酶发酵过程模拟

应用Matlab软件对聚乙烯醇降解酶发酵过程数学模型进行最优参数估计和非线性曲线拟合,得到了假单胞菌Pseudomonas sp XT11-Z90S发酵生产聚乙烯醇(PVA)降解酶的菌体生长、底物PVA消耗和聚乙烯醇降解酶合成的数学模型.结果表明,模型计算值和实验结果非常接近,其平均相对误差绝大部分小于10％,说明所建数学模型能较好地对聚乙烯醇降解酶发酵过程进行模拟.     

一株产普鲁兰酶芽孢杆菌的筛选鉴定及发酵条件优化

从甘肃定西某淀粉加工厂附近土壤中分离得到一株产普鲁兰酶酶源菌AI-1,通过形态学、生理生化试验及16S rRNA序列鉴定并对其进行系统发育分析,鉴定为解淀粉芽孢杆菌(Bacillus amyloliquefaciens),对其发酵培养基成分和发酵条件进行了优化。优化后的发酵培养基成分为:可溶性淀粉1.5%,酵母膏1%,蛋白胨1%,NaCl0.5%,K2HPO40.1%,MgSO4·7H2O 0.05%;最佳发酵条件为:培养温度36℃,发酵培养基初始pH 7.0,接种量8%(V/V),摇床转速150 r/min,发酵周期72 h。在此优化条件下,菌株AI-1发酵所产普鲁兰酶的酶活由最初的2.45 U/m L提高到了4.52 U/m L。     

一株产普鲁兰酶芽孢杆菌的筛选鉴定及发酵条件优化

从甘肃定西某淀粉加工厂附近土壤中分离得到一株产普鲁兰酶酶源菌AI-1,通过形态学、生理生化试验及16S rRNA序列鉴定并对其进行系统发育分析,鉴定为解淀粉芽孢杆菌(Bacillus amyloliquefaciens),对其发酵培养基成分和发酵条件进行了优化。优化后的发酵培养基成分为:可溶性淀粉1.5%,酵母膏1%,蛋白胨1%,NaCl0.5%,K2HPO40.1%,MgSO4·7H2O 0.05%;最佳发酵条件为:培养温度36℃,发酵培养基初始pH 7.0,接种量8%(V/V),摇床转速150 r/min,发酵周期72 h。在此优化条件下,菌株AI-1发酵所产普鲁兰酶的酶活由最初的2.45 U/m L提高到了4.52 U/m L。     

高活性漆酶产生菌的发酵条件优化

对云芝菌产漆酶的发酵条件进行优化,考察C源、N源和诱导剂等因素对产酶的影响.结果表明:杂色云芝菌摇瓶产漆酶的最佳条件为葡萄糖1.25 g/L,羧甲基纤维素钠15 g/L,酵母膏15 g/L,KH2PO41 g/L,CaCl20.05 g/L,MgSO40.25 g/L,30℃、150 r/m条件下振荡培养,在72 h加入2 mmol/L 2,5-二甲基苯胺作为诱导剂,在96 h加入2 mmol/L Cu2+,经过7 d培养,菌的漆酶比活达到3 319.2 U/mL.     

一株聚乙烯醇降解菌的降解特性

从腐败的PVA胶水中分离到一株能高效降解并矿化聚乙烯醇的细菌Xa-5,经初步鉴定属于黄单胞菌属（Xanthomonas sp.）.该菌株生长需要复杂的有机氮,蛋白胨和牛肉膏可提高该菌对聚乙烯醇的降解速率,其中蛋白胨的加量对降解聚乙烯醇影响较大.该菌降解聚乙烯醇要求的pH范围较宽.不同聚合度的聚乙烯醇对其降解速率影响不大.该菌的降解过程可能是聚乙烯醇首先吸附在细胞表面,然后进行氧化降解.在静息细胞降解过程中,以TOC表示,1 g•L^-1（DCW）菌体可在52 h内将1 g•L^-1聚乙烯醇基本矿化,但该菌株的PVA氧化酶酶活、脱氢酶酶活和PVA降解总酶活则较难测出.     

一株耐热脂肪酶产生菌的筛选、产酶及催化条件研究

通过平板划线分离法,从15份土样中筛选到18株产耐热脂肪酶菌株。经复筛选取K2菌进行产酶条件研究,并通过盐析沉淀法分离脂肪酶,研究该酶最佳催化条件。实验结果表明,该菌株产脂肪酶的适宜发酵条件为培养温度55℃,初始pH5,摇床转速200 r/min,发酵时间48 h。采用硫酸铵分30%与75%两步盐析分离脂肪酶,经真空低温冷冻干燥浓缩酶液,用pH 6.0磷酸缓冲液溶解后,在50℃,pH=7条件下,对乳化橄榄油具有最高催化活性。     

聚乙烯醇改性及降解研究进展

从材料学的改性技术和环境学的相容性两个角度综述了国内外聚乙烯醇生物降解的研究概况。通过聚乙烯醇溶液及薄膜的降解过程的介绍,指出化学改性和微生物降解的结合将是今后处理含聚乙烯醇类废水和固体废弃物的主要方法。     

聚乙烯醇改性及降解研究进展

聚乙烯醇是水溶性高分子树脂，由于其相对于其他聚乙烯类高分子树脂而言具有一定的可生物降解性，对于其生物降解的过程和机理的研究已越来越受到人们的关注。本文从材料学的改性技术和环境学的相容性两个角度综述了国内外聚乙烯醇生物降解的研究概况。通过聚乙烯醇溶液及薄膜的降解过程的介绍，指出化学改性和微生物降解的结合将是今后处理含聚乙烯醇类废水及固体废弃物的主要方法。     

产碱杆菌DN25的氰降解代谢途径分析与产酶条件优化

本实验室分离保藏的一株产碱杆菌Alcaligenes sp.DN25具有较高降氰活性,通过分析氰降解代谢产物确定了其降解途径,并根据降氰酶催化活性部位特征对产酶条件进行了优化.结果显示,氰的降解代谢途径可推断为由氰水解酶、氰水合酶和酰胺水解酶共同作用的水解途径,而其中氰水解酶的活性占主要作用;在培养基中分别添加4种含硫...     

Thermal characteristics of poly(vinyl alcohol) and poly(vinylpyrrolidone) IPNs

Interpenetrating polymer network (IPN) hydrogels based on poly(vinyl alcohol) (PVA) and 1‐vinyl‐2‐pyrrolidone (VP) were prepared by radical polymerization using 2,2‐dimethyl‐2‐phenylacetophenone (DMPAP) and methylene bisacrylicamide (MBAAm) as initiator and crosslinker, respectively. The thermal characterization of the IPNs was investigated by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and dielectric analysis (DEA). Depressions of the melting temperatures of PVA segments in IPNs were observed with increasing VP content via the DSC. The DEA was employed to ascertain the glass transition temperature (T_g) of IPNs. From the result of DEA, IPNs exhibited two T_gs indicating the presence of phase separation in the IPN. The thermal decomposition of IPNs was investigated using TGA and appeared at near 270°C. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 1844–1847, 2002     

The influence of poly(vinyl alcohol) suspending agents on suspension poly(vinyl chloride) morphology

The requirements for PVC suspension resin have changed considerably in the last few years, so much so that few companies have products on their ranges that are more than 4 or 5 years old. The suspending agent has a crucial influence on the morphology of the resin, so the changes in resin characteristics have largely been achieved by changes in the suspending agent systems. After a brief review of the mechanism of PVC suspension polymerisation, the properties of polymers made using PVOH suspending agents are related to changes in the latter. The effect of variations in PVAc degree of hydrolysis and viscosity are related to changes in surface tension. Methods of achieving higher porosity by using low hydrolysis co-suspending agents are described. It is shown that higher bulk densities can be achieved by delayed addition of the PVOH. Levels of conjugated unsaturation and copolymer distributions are also shown to have important influences.     

Surface grafting of a poly(organophosphazene) onto poly(vinyl alcohol) and poly(ethylene-co-vinyl alcohol) using triethoxysilane as a coupling agent

Triethoxysilane HSi(OEt)₃ was used as coupling agent to graft a poly(organophosphazene) (POPZ) containing allylic functions to the surface of poly(vinyl alcohol) or poly(ethylene-co-vinyl alcohol) films. Hydrolyzed HSi(OEt)₃, which contained both inorganic (Si–OH) and organic (Si–H) reactivities, acted at the interface between the hydroxylated substrates (via a condensation reaction) and the allylic functions in POPZ (via a hydrosilylation reaction). Starting materials and grafting surfaces were studied by ATR-IR and XPS spectroscopies and contact angle measurements. Data obtained indicated that different POPZ layers were produced, depending on whether the functionalization of materials with silane, and the grafting reaction were separately or simultaneously made. The POPZ layer thickness was higher when the grafting reaction was preceded by the POPZ functionalization. In each cases, the modified surfaces showed marked increases in hydrophobicity character. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 69: 1965–1974, 1998     

Effects of the tacticities of poly(vinyl alcohol) on the structure and morphology of poly(vinyl alcohol) nanowebs prepared by electrospinning

The effects of tacticities on the characteristics of poly(vinyl alcohol) (PVA) nanowebs prepared by an electrospinning technique were investigated. PVA webs composed of uniform nanofibers with syndiotactic dyad (s‐dyad) contents of 53.5 and 57.3% were successfully obtained with electrospinning. By changing processing parameters such as the initial polymer concentration, applied voltage, and tip‐to‐collector distance, we found suitable conditions for forming PVA webs with uniform nanofibers. PVAs of higher s‐dyad contents were prepared at a lower solution concentration and at a higher applied voltage because of the easy formation of syndiotactic PVA chain entanglements at a very low polymer concentration. The average diameter of the nanofibers in a PVA web with the higher s‐dyad content of 57.3% (ca. 240 nm) was thinner than that of the nanofibers in a PVA web with the lowers‐dyad content of 53.5% (ca. 270 nm). In addition, the crystallinity and thermal stability were greatly increased with an increase in the s‐dyad content. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Synthesis of poly(vinyl propionate) from poly(vinyl alcohol) in nonaqueous medium using ethyl nitrate dimethyl sulfoxide as a catalyst

Poly(vinyl alcohol) (PVA) can be dissolved in a nonaqueous medium in the presence of catalytic concentration of ethyl nitrate dimethyl sulfoxide, C₂H₅ONO₂·DMSO. From the PVA solution, poly(vinyl propionate), PVPR was prepared by the homogeneous esterification of PVA with propionic acid. The ester thus formed contained some unconverted hydroxyl group. The formation of the ester was confirmed by the IR and ¹H‐NMR spectra. The molecular weight of the ester was determined by GPC and intrinsic viscosity (η) was determined by viscometric method. Glass transition temperature, T_g, was obtained from differential scanning calorimetric (DSC) analysis. Thermal stabilities of the ester were checked by thermogravimetric analysis (TGA) and differential thermogravimetric (DTG) analysis. The efficiency of the ester as a flow improver of crude oil was also examined. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 5675–5679, 2006     

Crosslinked poly(vinyl alcohol) supports for the immobilization of a lipolytic enzyme

Different esters of crosslinked poly(vinyl alcohol) (PVA) were synthetized. They were developed for protein fractionation and immobilization. PVA was crosslinked with epichlorohydrin (CL‐PVA) and esterified with linear fatty acids of different length (Cn‐CL‐PVA). A characterization of the obtained products was made. The swelling behavior, the solubility, and the percentage of esterification were examined. Values of equilibrium water content of about 81% were reached for CL‐PVA samples. The polymers' stability and morpholgy were also investigated. Thermal analysis showed an increase in matrices stability, while SEM data showed the superficial development due to crosslinking and esterification reactions. Moreover, evident morphological inhomogeneities, mainly in the commercial and crosslinked products rather than in the final polymer, were present. Finally, immobilization experiments with a commercial crude of Candida rugosa were performed. Experiments showed a greater affinity of the protein for carbon chain length ranging from 8 to 12. Data indicated that compared to Celite 545, C8‐CL‐PVA was a better support for enzyme immobilization by physical adsorption, confirming the fact that microbial lipases prefer hydrophobic supports. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 1881–1889, 1999     

Properties of branched and network poly(vinyl alcohols) prepared with poly(vinyl alcohol) having aldehyde groups at the chain ends

Branched and network poly(vinyl alcohols) (PVAs) were prepared with inter-acetalization of the PVA with aldehyde groups at the chain ends which was prepared by the cleavage of 1,2 glycol bonds in commercial PVA. The numbers of branches estimated from molecular weights were compared with those estimated by theory. Huggins' constant and crystallinity decreased with increasing branch number. Dissolution of branched PVAs into dimethylsulphoxide was not so easy compared with commercial PVA. The colour of branched PVA–iodine complex decreased rapidly with standing while that of commercial PVA decreased gradually. Network PVAs with Young's modulus of 1–8 MPa were prepared.