有机生姜生产的关键技术及规范研究

本文通过对有机生姜生产基地建设的研究实践,总结阐述了有机生姜栽培中基地选择、土壤培肥、病虫草防治、轮作模式和姜田覆草等关键技术,提出了生产中的一些操作规范要求和建议。     

Activation of protease by sol-gel entrapment into organically modified hybrid silicates

To prepare an immobilized protease with a high activity for transesterification of vinyl n-butyrate with 3-methyl-1-butanol (isoamyl alcohol) in organic media, a protease was entrapped into organic–inorganic hybrid silica gel on Celite 545 by the sol-gel method. When propyltrimethoxysilane was used as the organic silane precursor mixed with tetramethoxysilane at a molar ratio of 16:1, the hybrid gel-entrapped protease on Celite 545 had 8 times the activity of the protease deposited on Celite 545 from 35 to 85°C.     

有机物料对土壤镉形态及其生物有效性的影响

采用盆栽试验,研究了淹水种稻条件下添加猪粪和泥炭对红壤和潮土中内源和外源Cd形态及其生物有效性的影响。结果表明,土壤中内源Cd在各形态之间的分布比较均匀;添加外源Cd时Cd主要分布于交换态,从分蘖期到成熟期,内源Cd交换态普遍升高,添加外源Cd时交换态普遍降低。有机物料对内源Cd交换态的影响不显著,但当添加外源Cd时则对交换态有显著影响,在不添加外源Cd的条件下,有机物料普遍促进水稻根系对Cd的吸收。在添加外源Cd的条件下,有机物料普遍抑制水稻根系对Cd的吸收,猪粪的抑制效果强于泥炭,水稻根系对Cd与Fe的累积呈显著抑制作用。     

有机溶剂对缢蛏碱性磷酸酯酶分子构象和催化活力的影响

本文初步研究了三种有机溶剂甲醇、二甲基甲酰胺、二氧六环对缢蛏碱性磷酸酯酶(ALP)分子构象和催化活力的影响。发现在有机溶剂作用下,ALP的荧光发射光谱、紫外差光谱、园二色光谱都发生了显著的变化,而酶经甲醇、二甲基甲酰胺预处理后酶活力提高,经二氧六环预处理后活力下降,但当测活体系中有三种有机溶剂存在时,酶的活力却被大大抑制。     

不同发酵条件下产甘油假丝酵母有机酸代谢的研究

产甘油假丝酵母 (Candidaglycerolgenesis)发酵产生的有机酸对丙三醇产品质量和产率均有影响。发现在发酵其它条件恒定 ,装液比和玉米浆浓度增加时 ,发酵液总酸是递增的。在装液比为 0 2和玉米浆浓度为 8g L时 ,丙酮酸和乳酸在细胞生长期可分别积累达 4 1g L和 1 0g L ,比正常发酵时增加 2倍以上 ,丙三醇产率也低 ;然而 ,装液比为 0 0 8和玉米浆浓度为 4g L时 ,丙酮酸和乳酸产生较低 ,丙三醇产率较高 ,但乙酸积累比供氧不足时高 ,可达 2 6g L。发酵过程中有机酸被细胞代谢 ,含量逐渐下降 ,如在初糖浓度为 1 0 0g L时 ,有机酸在细胞生长期积累至高峰后 ,丙三醇和有机酸随之均降低至较低含量 ,并且丙酮酸或乳酸可以转化为乙酸。此外 ,在外加一些添加剂时对其产生有机酸也有影响 ,如添加 1 %油酸和VB1时可以降低乙酸的积累 ,同时增加丙酮酸的含量 ,丙三醇产量也有所增加 ;而丙酮酸结构类似物氟代丙酮酸和亚硫酸盐促进乙酸的产生 ,使酮戊二酸合成减少 ,丙三醇产量约增加 2 0 %。     

利用氮同位素技术探讨天津地表水氮污染

地表水的氮污染状况与水质、区域景观等密切相连。本文分析了天津地表水的三氮(NO3-N、NH4+-N、NO2-N)组成,以及部分水样NO3-N和NH4+-N的N同位素组成。结果显示:NO3-N的含量为0.01～16.51mg.L-1,均值为2.25mg.L-1,部分样品NO3-的含量超过50mg.L-1(以NO3-N计为11.29mg.L-1);NH4+-N的含量为0～10.60mg.L-1,均值为1.15mg.L-1,有1/4水样超过1.5mg.L-1;另外,在所有样品中有1/12水样有较高的NO2-N。NO3-N为大部分水样无机氮的主要形态,污水等部分水样以NH4+-N为主要形态。NO3-N同位素值的变化范围为-5.5‰～+28.6‰,均值为+9.0‰(n=49),中值为+8.5‰;NH4+-N同位素值的变化范围为-8.8‰～+34.3‰,均值+11.6‰(n=11),中值为+13.6‰。水化学和同位素结果分析表明,该区地表水的氮主要来源为生活污水,而且氮形态转化受硝化作用、挥发作用以及可能的反硝化作用影响明显。     

A rapid and direct method for the determination of active site accessibility in proteins based on ESI-MS and active site titrations

We have developed an electrospray ionisation mass spectrometry (ESI-MS) technique that can be applied to rapidly determine the number of intact active sites in proteins. The methodology relies on inhibiting the protein with an active-site irreversible inhibitor and then using ESI-MS to determine the extent of inhibition. We have applied this methodology to a test system: a serine protease, subtilisin Carlsberg, and monitored the extent of inhibition by phenylmethylsulfonyl fluoride (PMSF), an irreversible serine hydrolase inhibitor as a function of the changes in immobilisation and hydration conditions. Two types of enzyme preparation were investigated, lyophilised enzymes and protein-coated microcrystals (PCMC).     

Simultaneous removal of carbon and nitrogen from municipal-type synthetic wastewater using net-like rotating biological contactor (NRBC)

The treatment of municipal-type synthetic wastewater was carried out using a three stages net-like rotating biological contactor (NRBC). The results indicated that, compared with conventional rotating biological contactor (RBC), NRBC have several advantages, such as quick start-up, high biomass concentration and can handle high organic loading rates. The COD and total nitrogen removal rates achieved were 78.8–89.7% and 40.2–61.4%, respectively, in aerobic treatment of low COD municipal-type wastewater at hydraulic retention times (HRT) from 5 to 9 h. The COD removal rate achieved 80–95% when organic loading varied between 16 and 40 gCOD/m² d. A large amount of nematodes were found in the NRBC system, which made the NRBC system produce relatively low amounts of waste sludge, due to their grazing.     

Taenia crassiceps organic acids detected in cysticerci

Taenia crassiceps cysticerci is used as an experimental model to cysticercosis studies; however there are subcutaneous cases of cysticercosis caused by these cysticerci. It remains unclear in the literature the energetic and fatty acid metabolism in cestodes. Its metabolic study may provide knowledge of pathways that may serve as potential anti-helminthic drugs sites of action. In this work we studied the citric acid cycle organic acids and the fatty acid oxidation in cysticerci removed from mice with 21 and 42 days of infection in two different evolutive stages: growing and final. The organic acids were extracted using perchloric acid and analyzed by HPLC methodology. We found significant statistically differences in oxalate, malate, lactate, and beta-hydroxybutirate concentrations between cysticerci. These results indicate the aerobic metabolism in vivo in spite of the low oxygen concentration of its habitat, and also indicate the presence of fatty acid oxidation as an alternative energetic source.     

Molecular modeling of the human multidrug resistance protein 1 (MRP1/ABCC1)

Multidrug resistance protein 1 (MRP1/ABCC1) is a 190 kDa member of the ATP-binding cassette (ABC) superfamily of transmembrane transporters that is clinically relevant for its ability to confer multidrug resistance by actively effluxing anticancer drugs. Knowledge of the atomic structure of MRP1 is needed to elucidate its transport mechanism, but only low resolution structural data are currently available. Consequently, comparative modeling has been used to generate models of human MRP1 based on the crystal structure of the ABC transporter Sav1866 from Staphylococcus aureus. In these Sav1866-based models, the arrangement of transmembrane helices differs strikingly from earlier models of MRP1 based on the structure of the bacterial lipid transporter MsbA, both with respect to packing of the twelve helices and their interactions with the nucleotide binding domains. The functional importance of Tyr³²⁴ in transmembrane helix 6 predicted to project into the substrate translocation pathway was investigated.