Modeling uranium biosorption by Cystoseira sp. and application studies

The aim of the present work was to determine the applicability of raw and modified brown macroalga Cystoseira sp. as a biosorbent material for the sorption of uranium ions from aqueous solutions. Equilibrium of uranium biosorption was analyzed under isotherm models and thermodynamic parameters of the process. Recovery of uranium from acidic mine wastewater was also applied. The mechanism of biosorption was discussed considering experimental data and theoretical models. The bioremoval efficiency of modified biomass was higher than raw Cystoseira sp. and the theoretical biosorption capacity of modified biosorbent was calculated to be 468.01 mg U/g.     

Genes Involved in the Endoplasmic Reticulum N-Glycosylation Pathway of the Red Microalga Porphyridium sp.: A Bioinformatic Study

N-glycosylation is one of the most important post-translational modifications that influence protein polymorphism, including protein structures and their functions. Although this important biological process has been extensively studied in mammals, only limited knowledge exists regarding glycosylation in algae. The current research is focused on the red microalga Porphyridium sp., which is a potentially valuable source for various applications, such as skin therapy, food, and pharmaceuticals. The enzymes involved in the biosynthesis and processing of N-glycans remain undefined in this species, and the mechanism(s) of their genetic regulation is completely unknown. In this study, we describe our pioneering attempt to understand the endoplasmic reticulum N-Glycosylation pathway in Porphyridium sp., using a bioinformatic approach. Homology searches, based on sequence similarities with genes encoding proteins involved in the ER N-glycosylation pathway (including their conserved parts) were conducted using the TBLASTN function on the algae DNA scaffold contigs database. This approach led to the identification of 24 encoded-genes implicated with the ER N-glycosylation pathway in Porphyridium sp. Homologs were found for almost all known N-glycosylation protein sequences in the ER pathway of Porphyridium sp.; thus, suggesting that the ER-pathway is conserved; as it is in other organisms (animals, plants, yeasts, etc.).     

Effects of latitude and weather conditions on sugars,fruit acids and ascorbic acid in currant (Ribes sp.) cultivars

BACKGROUND: Sugars, acids and vitamin C are essential components influencing the sensory and nutritional properties of currants (Ribes sp.). In this study the effects of growth latitude and weather conditions on these components in red, white and green currant cultivars were systematically investigated for the first time. RESULTS: Red Dutch (a red Ribes rubrum cultivar) contained more malic acid but fewer sugars and had a lower sugar/acid ratio than Vertti (a green Ribes nigrum cultivar) and White Dutch (a white R. rubrum cultivar). Fructose (27–56 g L^?1 juice) and glucose (21–54 g L^?1) were the major sugars in all currant samples, but sucrose (7–20 g L^?1) was present only in Vertti. Vertti contained the most ascorbic acid. Sugars, malic acid and the sugar/acid ratio in Red Dutch were 11–28% higher in southern Finland than in northern Finland. The corresponding values in Vertti were 6–16% lower in the south than in the north, but no differences were found in White Dutch. As the relative humidity decreased, the amounts of citric acid and total acid increased in all cultivars, while the amount of sugars increased in Vertti but decreased in White Dutch and Red Dutch. In Red Dutch, high temperature and radiation levels increased the sugar content. CONCLUSION: The influence of latitude and weather conditions on qualitative parameters of currants varies with the cultivar. This study provides important guidance for currant cultivation and for further physiological and enzymological studies. Copyright © 2009 Society of Chemical Industry     

FAME Production and Fatty Acid Profiles from Moist Chlorella sp. and Nannochloropsis oculata Biomass

In the present study, we investigated the production of fatty acid methyl esters (FAME) from moist Chlorella sp. and Nannochloropsis oculata biomass using a hydrolysis–esterification process. Additionally, we evaluated for the first time the fatty acid profile before and after this process. Hydrolysis of the lipid fraction was performed on a moist biomass in the presence of differing amounts of an acid catalyst in both 50 and 100 % w/w water relative to the biomass. The esterification of the crude extracts of the free fatty acids (FFA) was then investigated. The experiments show that in the presence of 50 % w/w water relative to the biomass, the hydrolysis–esterification process results in higher FFA and FAME yields. The analysis of the fatty ester profiles did not reveal any degradation of the FFA from the microalgae biomass under the hydrolysis–esterification conditions. The results were compared with both extraction–transesterification and direct transesterification processes using dry biomass. The extraction–transesterification and hydrolysis–esterification processes resulted in similar FAME yields and similar profiles of the fatty esters from dry and moist biomass materials, respectively.     

海洋环境中假单胞菌对聚氨酯清漆涂层分解的影响

目的 研究在海洋环境中假单胞菌对聚氨酯清漆涂层分解作用的影响。方法 将聚氨酯清漆涂层样品分别浸泡于无菌海水与含假单胞菌的海水中,对浸泡环境不同的样品利用电化学阻抗谱（EIS）评价涂层防腐性能,使用扫描电子显微镜（SEM）和傅里叶变换红外光谱（FTIR）,观察对比涂层的表面形貌,并表征其分子结构变化。结果 1 h~35 d时,在无菌海水及假单胞菌海水中,样品Nyquist图的容抗弧直径以及Bode图的低频端阻抗模量均减小。与此同时,假单胞菌海水中浸泡样品的Nyquist图容抗弧直径与Bode图低频端阻抗模量的减小量明显大于无菌海水中的减小量。无菌海水浸泡的等效电路在1~48 h时为1个时间常数,5~35 d时增加为2个时间常数;假单胞菌海水浸泡的等效电路在1~48 h时只有1个时间常数,5~29 d时为2个时间常数,35 d时增加为3个时间常数。浸泡36 h时,无菌海水中浸泡样品的涂层电阻值为8.23× 107 Ω?cm2,而假单胞菌海水中样品的涂层电阻为5.14×107 Ω?cm2;至35 d时,无菌海水中样品的涂层电阻降为5.61×106 Ω?cm2,假单胞菌海水中样品的涂层电阻降至7.03×105 Ω?cm2。假单胞菌海水中样品的涂层电阻在36 h~35 d的减小量明显大于无菌海水中的减小量。由SEM结果可以观察到,浸泡30 d后,无菌海水中浸泡样品的表面光滑完整,而在含假单胞菌海水中的样品表面附着了大量细胞及其代谢产生的生物膜,并出现了大量微孔与粉化痕迹。通过FTIR结果可以发现,浸泡在假单胞菌海水中的样品的N—H和醚基中的C—O含量明显比无菌海水中浸泡的样品要低。结论 电化学结果表明,假单胞菌显著降低了涂层的腐蚀抗性,并导致了涂层的分解。SEM和FTIR的分析结果证明,假单胞菌通过破坏聚氨酯分子中的N—H和醚基中的C—O,造成了涂层的分解。     

煤矿生产中事故危险点的控制

在煤矿生产中要注重事故危险点的控制 ,及时准确地发现、确认事故危险点 ,推出控制的具体方法和措施 ,保证煤矿的安全生产     

Alterations in Membrane Phospholipid Fatty Acids of Gram-Positive Piezotolerant Bacterium Sporosarcina sp. DSK25 in Response to Growth Pressure

Pressure is an important thermodynamic property of the ocean and the deep biosphere that affects microbial physiology and biochemistry. Here, we report on our investigation of the response of Gram-positive piezotolerant bacterium Sporosarcina sp. DSK25 to hydrostatic pressure. Strain DSK25 responded in an adaptive manner to upshifts of growth pressure and showed systematic changes in phospholipid fatty acids. As the pressure increased from 0.1 to 10 MPa (Megapascal), unsaturated fatty acids in DSK25 increased from 21.7 to 31.1 % of total fatty acids, while the level of iso- and anteiso-branched fatty acids remained unchanged. At higher pressures (30, 50, and 60 MPa), the amount of unsaturated fatty acids decreased, and that of anteiso-branched fatty acids increased from 34.4 to 49.9 % at the expense of iso-branched fatty acids. For the first time, two polyunsaturated fatty acids (PUFA), 18:2n-6 and 18:2n-x, with the latter having much higher abundance than the former, were identified in DSK25. The concentration of the PUFA increased with growth pressure. These results indicate the involvement of unsaturated and methyl-branched fatty acids in the modulation of bacteria membrane fluidity and function over environmentally relevant parameter (pressure). Piezotolerant bacterium Sporosarcina sp. DSK25 appears to utilize two regulatory mechanisms for adaptation to high pressure, a rapid-responding mechanism on transient scale, expressed as increased biosynthesis of monounsaturated fatty acids, and a long-term adaptation mechanism in increased synthesis of anteiso-branched and polyunsaturated fatty acids. Our results further suggest that Gram-positive piezophilic bacteria respond differently than Gram-negative bacteria in adaptation to high pressure.     

黄绿木霉纤维素酶提纯及其性质研究

通过(NH4)2SO4分级沉淀、Sephadex G-100分子筛层析和DEAE Sephadex A-50离子交换层析等步骤,分离纯化出木霉T2纤维素酶系中达到电泳纯的3种内切葡聚糖酶(EGⅠ、EGⅡ、EGⅢ)和2种β-葡萄糖苷酶(BGⅠ、BGⅡ).通过SDS-PAGE和IEF电泳测得5个酶组分的相对分子质量分别为62.3 ku、71.9 ku、52.6 ku、85.3 ku和78.3 ku,等电点分别为5.4、4.8、5.0、5.6和5.8.此酶系均为糖蛋白,含糖量分别为17.7%、11.7%、15.6%、17.8%、19.3%.5个酶组分均属酸性纤维素酶,最适pH都是5.0;3种内切葡聚糖酶的最适温度皆为60℃,2种β-葡萄糖苷酶的最适温度都是55℃.Mn2 、Fe2 、Zn2 对5种纤维素酶都有一定的激活作用,尤其是Mn2 对内切葡聚糖酶的激活作用极为显著;Mg2 、Cu2 、脲对5种纤维素酶都具有不同程度的抑制作用.酶学动力学分析表明5种纤维素酶组分的Km值分别为0.093、0.083 8、0.079 0、0.085 1和0.077 8 mg/mL,Kcat值为101.7、119.6、11.4、111.4和162.1 s-1.内切葡聚糖酶对底物CMC-Na亲和力的大小与酶的催化效率之间并无相关性,BG对底物水杨苷亲和力的大小与酶的催化效率之间有一定的相关性.β-葡萄糖苷酶有较高的底物专一性,只对水杨苷有活力;内切葡聚糖酶在对羧甲基纤维素钠有活力的同时,对滤纸和秸秆粉也有微弱的活力.