产高温碱性蛋白酶菌株筛选及酶学性质研究

从高温堆肥土样中筛选到一株高产蛋白酶的菌株,经鉴定为Bacillus subtilis,命名为I15.对最适产酶发酵条件进行了优化,并研究了发酵产蛋白酶的酶学性质.结果表明,玉米淀粉和豆饼粉是该菌发酵产蛋白酶的最适经济碳氮源;该蛋白酶属高温碱性蛋白酶,具有很强的热稳定性和酸碱稳定性.另外,突出的性质是该蛋白酶对表面活性剂和温和型去垢剂具有超强的耐受性,将具有广阔的市场前景.     

产高温蛋白酶高温菌的筛选

利用平板透明圈法，从堆肥、土壤中筛选到88种产高温蛋白酶的高温菌，它们在酪素筛选平板上都产生明显的蛋白水解透明圈。这些产高温蛋白酶高温菌株的获得为进一步研究高温菌的耐热机制、高温酶的热稳定性机理等理论问题及高温蛋白酶的应用，奠定了基础。     

Sulfolobus tokodaii strain 7高温酸性α-淀粉酶基因在大肠杆菌中克隆表达及其酶学性质

以超嗜热古菌Sulfolobus tokodaii strain 7基因组DNA为模板,通过PCR扩增高温酸性α-淀粉酶基因ST0817,将此基因克隆至表达载体pET15b,并转化大肠杆菌Escherichia coli BL21-CodenPlus(DE3)-RIL,获得重组大肠杆菌工程菌。通过热处理、镍柱亲和层析和分子筛层析,得到纯化重组酶,SDS-PAGE分析表明,该酶分子量为53.0 kDa。酶学性质研究表明,该酶最适温度和pH分别为75℃和5.5;具有较强的热稳定性和pH稳定性,在85℃处理8 h保持50%左右活力,在pH 5.2处理120 min仍保持50%活力。此酶对不同底物水解活性不同,直连淀粉>可溶性淀粉>支链淀粉>β-极限糊精>糖原>环糊精>普鲁兰糖;该酶对有机溶剂、变性剂和金属离子具有一定抗性。     

一株嗜热菌产耐热木聚糖酶对馒头品质和保质期的影响

研究嗜热细菌Geobacillus sp. PZH1产耐热木聚糖酶对馒头品质及保质期的影响作用。从嗜热细菌Geobacillus sp. PZH1制备木聚糖酶,添加到面粉中制作馒头,观察其对馒头品质和保质期的影响。结果表明：在馒头中添加适量的耐热木聚糖酶,能明显降低馒头的持水性,提高面筋网络的弹性,改变面团的加工及稳定性能,增大馒头体积,并能有效抑制馒头中细菌的生长,延长馒头的保质期。     

气升式反应器中细菌氧化预处理 难浸金精矿的浸出参数优化

依据三相内循环流化床结构模型, 设计了实验室规模的气升式生物反应器, 用于高砷难处理金精矿的细菌氧化预处理。从酸性矿坑水中筛选到一种中度嗜热混合菌, 驯化后可在45 ℃, pH值1.2, As(As³⁺和As⁵⁺)浓度15 g/L条件下良好生长, 并且对难浸金精矿具有较好的氧化浸出能力。在气升式反应器中采用驯化后的混合菌氧化浸出高砷难浸金精矿, 设计正交实验研究矿物粒度、矿浆浓度、反应器充气量和初始pH值对浸出的影响, 结果得出矿物粒度-37 μm, 矿浆浓度5%, 充气量4 L/min, 初始pH值1.2为该反应器最佳浸出参数组合, 在此条件下高砷金精矿砷脱除率可达到95%。     

大庆头台油田微生物驱油先导性矿场试验室内评价研究

选定进行微生物先导性矿场试验的大庆头台油田,有效孔隙度11.5%,平均渗透率0.125μm2,油层温度60～65℃,原油含蜡25%,凝固点31.5℃,地下粘度4.0mPap·s,地面密度0.8624t/m3,地层水矿化度627mg/L,pH值7～8。对筛选出的多株采油菌进行了室内评价,结果表明:6个菌种(P24,SHB,X2,RB,A白,AQ)在65℃下与头台原油共同发酵后,原油中轻组分增加,按参数∑C21/∑C22计算的增加率为41.0%～97.0%,以X2(97.0%)和SHB(94.0%)为最高;原油粘度(48.9mPa·s)下降17.7%～44.2%,以A白(44.2%)和SHB(41.5%)下降最多;发酵液pH值由7.0降至5.0～6.0,发酵液与原油间的界面张力(35.6mN/m)下降56.8%～66.3%;5个菌种(SHB,X2,P24,U1 6,A白)在45～65℃下都能生长,菌数达108～1010个/mL以上;7种菌(以上5种及AU1,5号)尺寸最大为1.2～2.4μm,与头台油藏的渗透率相适应;在渗透率0.559,0.581,0.590μm2的2个均质、1个非均质人造岩心上,水驱之后(水驱采收率33.1%,36.5%,53.6%)注入菌数为107～108个/mL的菌液0.3PV,继续水驱,流出液菌数为108～109个/mL,采收率提高6.08%,5.81%,4.60%,平均为5.81%。图2表6参5。     

Purification of an Inducible DNase from a Thermophilic Fungus

The ability to induce an extracellular DNase from a novel thermophilic fungus was studied and the DNAse purified using both traditional and innovative purification techniques. The isolate produced sterile hyphae under all attempted growing conditions, with an average diameter of 2 μm and was found to have an optimal temperature of 45 °C and a maximum of 65 °C. Sequencing of the internal transcribed region resulted in a 91% match with Chaetomium sp., suggesting a new species, but further clarification on this point is needed. The optimal temperature for DNase production was found to be 55 °C and was induced by the presence of DNA and/or deoxyribose. Static growth of the organism resulted in significantly higher DNase production than agitated growth. The DNase was purified 145-fold using a novel affinity membrane purification system with 25% of the initial enzyme activity remaining. Electrophoresis of the purified enzyme resulted in a single protein band, indicating DNase homogeneity.     

Effect of some operating parameters on biogas production rate

In order to enhance the performance of a biogas generation process and prevent process failure, certain operataing parameters need to be controlled. This article presents the results of a series of studies in which the effect of temperature, pH, carbon -nitrogen ratio and retention time on biogas production from cowdung were investigated     

Improvement of treatment efficiency of thermophilic oxic process for highly concentrated lipid wastes by nutrient supplementation

The biodegradation of highly concentrated lipid wastes was conducted by a thermophilic oxic process (TOP). In order to improve the treatment efficiency of TOP, the stimulatory effect of nutrient supplementation was examined. A model nutrient supplement that satisfied the essential components necessary to promote degradation of lipid wastes was developed. The importance of balanced nutrient supplement consisting of organic and inorganic components was demonstrated. Regardless of the source of either vegetable oil or animal fat, the combination of 1.5 g of yeast extract, 1 g of urea and 60 ml of trace-element solution was effective to stimulate the degradation of 15 g of lipids by TOP. With this combination, degradation efficiencies of 68% and 77% in a 120-h treatment were attained for salad oil and lard, respectively. The conversion ratio of degraded lipid materials to CO2 was 0.91, confirming the advantage of TOP, i.e., very low excess sludge generation. The effectiveness of the model nutrient supplement for stimulating the degradation of lipid materials by TOP was also confirmed when tested on three kinds of actual highly concentrated lipid wastes. A constant degradation efficiency of around 60% in a 120-h treatment was attained for all lipid wastes although further improvement of degradation efficiency was possible by some nutrient addition into the model supplement combination. Based on the model nutrient supplement, the essential components for stimulating oil degradation by TOP and the possible alternative materials for the model nutrient supplement were discussed. The results demonstrated the possibility of employing TOP (stimulated by nutrient supplement) as a new biological treatment strategy for highly concentrated lipid wastes.