不同基质配比对农村生活垃圾厌氧发酵效率及稳定性的影响

以典型农村生活垃圾餐厨垃圾(Food Waste,FW)与纸类垃圾(Paper Waste,PW)为基质,通过中温(35℃)批次厌氧共发酵试验,探明不同配比的基质在厌氧共发酵4阶段(水解阶段、酸化阶段、乙酸化阶段、产甲烷阶段)的动力学特性,再结合挥发性脂肪酸(Volatile fatty acids,VFAs)在系统运行过程中的变化,确定FW与PW的最佳配比。结果表明,水解阶段是纸类垃圾的主要限速步骤,而VFAs积累限制了餐厨垃圾甲烷化进程的提高,且VFAs积累主要以丙酸与丁酸为主。当w(FW)≥35%时,产甲烷速率随VFAs质量浓度增大而线性减小,过高的VFAs质量浓度抑制了产甲烷菌的活性。FW与PW最佳基质配比为35∶65(质量比),在此条件下反应速率最为突出,系统运行高效,VFAs能及时被产甲烷菌利用,无有机酸积累,系统运行平稳。     

基于PLFA法分析亚硝氮、硝氮和氨氮对厌氧微生物细菌群落的影响

利用磷脂脂肪酸(PLFA)技术研究了亚硝氮、硝氮和氨氮在不同浓度水平下对中温厌氧颗粒污泥中厌氧细菌群落结构的影响.结果表明,高浓度亚硝氮(360 mg·L-1,以N计)、硝氮(300 mg·L-1,以N计)和氨氮(3000 mg·L-1,以N计)使系统COD去除率分别下降至3.49%、10.85%和71.53%,并使污泥表面主要细菌由杆菌变为球状菌;亚硝氮和硝氮引起厌氧细菌和革兰氏阳性菌的含量下降,氨氮引起革兰氏阴性菌的含量下降;PLFA香农-威尔多样性指数随着亚硝氮和硝氮浓度的升高从1.12分别下降至0.96和1.03,氨氮对PLFA香农-威尔多样性指数无明显影响.     

生物质炭对邻苯二甲酸二丁酯污染土壤微生物群落结构多样性的影响

在邻苯二甲酸二丁酯(DBP)污染的不同类型土壤(有机质含量低的新垦红壤、有机质含量高的熟化红壤)中添加不同种类(稻草炭、毛竹炭)以及不同用量(0%、0.5%和2%)的生物质炭,温室种植上海青并在56 d后采集土样,采用磷脂脂肪酸法(PLFA)考察了土壤类型、生物质炭种类以及用量对土壤微生物群落结构多样性的影响.结果表明:对细菌、真菌及微生物总PLFA这三者的含量而言,熟化红壤显著(p0.05)高于新垦红壤,熟化红壤中添加2%稻草炭使其显著(p0.05)增加,新垦红壤中添加毛竹炭使其显著(p0.05)降低.新垦红壤中添加2%稻草炭对革兰氏阴性菌/革兰氏阳性菌比值的增加效果最显著(p0.05),添加2%毛竹炭对土壤微生物群落Shannon指数的降低效果最显著(p0.05).添加2%稻草炭对DBP污染土壤中微生物压力指数降低效果最显著(p0.05).生物质炭对熟化红壤中真菌/细菌、革兰氏阴性菌/革兰氏阳性菌及微生物群落Shannon指数均无显著影响.PCA分析表明,土壤有机质含量以及生物质炭的种类和用量均会对土壤微生物群落结构产生一定影响,且生物质炭的影响与土壤有机质含量密切相关.     

污泥厌氧发酵产酸关键影响因素的函数模型研究

本研究以城市剩余污泥预处理液作为底物,调节底物不同C/N比,测定了厌氧发酵过程中几种关键酶的酶活及发酵产物乙酸、丙酸及丁酸的浓度.同时,利用Matlab软件通过回归分析和函数拟合构建了C/N比-关键酶活-酸产量之间的多项式函数模型,发现所建立的二元三次多项式模型的拟合优度R2均大于0.9,且残差平方和较小,因此,判定二元三次多项式更适合描述C/N比-关键酶活-酸产量的数学关系.最后,建立了关键酶活、C/N比和产酸量三因素间的曲面模型,发现该模型能够很好地描述污泥厌氧发酵中C/N比条件对关键酶和产酸类型的影响,并能进一步预测C/N比所对应的酶活和产酸发酵类型,可为今后的实验研究及工程放大提供理论参考.     

Natural resistance of rose petals to microbial attack

Petals of red, yellow and white roses (Rosa damascene Mill.) of the family Rosaceae were extracted with (1:1) methylene chloride/methanol and tested for their antimicrobial activities against four species of Gram-positive bacteria (Bacillus cereus, Bacillus subtilis, Micrococcus luteus and Staphylococcus aureus), five species of Gram-negative bacteria (Enterobacter aerogenes, Escherichia coli, Klebsiella pneumonia, Pseudomonas aeruginosa and Serratia marcescens) and five species of fungi (Penicillium notatum, Aspergillus niger, Rhizopus stolonifer, Saccharomyces cerevisiae and Fusarium oxysporum). All of the crude extracts showed a wide range of antimicrobial activities according to the tested organism and rose's type. Micrococcus luteus was found to be the most susceptible bacteria to all crude extracts. Red and yellow petal extracts showed much higher antibacterial activity than the white petals extract. Bacillus subtilis was found to be the least susceptible to all extracts. The fungus, Penicillium notatum was found to be the most susceptible with white petal extract being the most effective. Saccharomyces cerevisiae and Fusarium oxysporum were the least susceptible to all extracts. White roses extract showed much higher antifungal activities against Penicillium notatum than red or yellow roses, therefore, it was subjected to several bioassay guided chromatographic fractionations and purification to isolate the active chemical(s) responsible for the antifungal activity. Chemical structure of the isolated antifungal compounds were identified by spectroscopy techniques and found to be a γ-sitosterol and (Z,Z)-9,12-octadecadienoic acid. Antibacterial activity of the various types of rose extracts were due to complex mixtures of organic compounds which are still under chemical investigation and will be published later.     

Zeolites relieves inhibitory stress from high concentrations of long chain fatty acids

Protein and fat rich slaughterhouse waste is a very attractive waste stream for the production of biogas because of the high biochemical methane potential of the substrate. The material has however some drawbacks as the sole material for biogas production due to the production of several process disturbing metabolites such as ammonia, sulfides and long chain fatty acids. We can in this work present results that show that zeolites have the potential to relieve inhibitory stress from the presence of long chain fatty acids. Moreover, the results strongly indicate that it is mainly acetic acid consumers that are most negatively affected by long chain fatty acids and that the mechanism of stress relief is an adsorption of long chain fatty acids to the zeolites. In addition to this, it is shown that the effect is immediate and that only a small amount of zeolites is necessary to cancel the inhibitory effect of long chain fatty acids.     

短链氯化石蜡暴露对HepG2细胞代谢的影响

短链氯化石蜡(short-chain chlorinated paraffins,SCCPs)是一组成分复杂的氯代正构烷烃,在环境中普遍存在。然而有关其毒性机理的信息十分有限,限制了对其健康风险的评估。本研究采用液相色谱–串联质谱(LC-MS/MS)分析技术,研究了不同剂量的SCCPs暴露(0、1.0、10.0和100.0μg·L-1;C13-CPs;55.0%Cl)对人体肝癌细胞Hep G2的糖代谢、氨基酸代谢和脂肪酸代谢的影响。通过偏最小二乘判别分析(PLS-DA)鉴别各组代谢产物谱差异,发现3个SCCPs暴露剂量组均能够与对照组完全分开,表明SCCPs短期暴露能够引起细胞代谢活动的显著改变。SCCPs的低剂量暴露可明显刺激Hep G2细胞对氨基酸的吸收。与对照组相比,SCCPs低剂量暴露组(1.0μg·L-1)培养基中谷氨酰胺、色氨酸和丝氨酸的含量显著(P0.05)降低。而高剂量SCCPs(100.0μg·L-1)暴露抑制了细胞对氨基酸和葡萄糖吸收,但促进了乳酸、丙氨酸、半胱氨酸的生成。氨基酸吸收的抑制不可避免地会影响蛋白质的合成。同时,SCCPs的暴露使饱和脂肪酸代谢紊乱,使不饱和脂肪酸水平上调。为确定SCCPs的毒性作用方式,有必要从转录组和蛋白组层面进一步研究其毒性机制。     

Variation in soil organic carbon mineralization and microbial community structure induced by the conversion from double rice fields to drained fields北大核心CSCD

Land use conversion is an important factor influencing the carbon gas exchange between land and atmosphere. The effect of land use conversion on soil organic carbon mineralization and microbial function is important for soil organic carbon sequestration and stability. This research studied the effects of land use conversion on soil chemical properties, organic carbon mineralization and microbial community structure after two years of conversion from double rice cropping (RR) to maize-maize (MM) and soybean-peanut (SP) double cropping systems in southern China. The results showed that soil pH significantly decreased by 0.50 (MM) and 0.52 (SP, P = 0.002), and dissolved organic carbon significantly increased by 23%- 35% (P = 0.016). No significant difference was found in soil organic carbon mineralization rate with the land use conversion, though the accumulated mineralization decreased after 13 days of incubation (P = 0.019). Land use conversion from paddy to upland significantly changed soil microbial community structure. The total PLFAs, bacterial, gram-positive bacterial (G+), gram-negative bacterial (G-) and actinomycetic PLFAs decreased significantly (P < 0.05), the ratio of fungal PLFAs to bacterial PLFAs (F/B) increased significantly (P = 0.006). But no significant differences in microbial groups were found between MM and SP. The accumulated mineralization at the beginning period of the incubation were significantly positively correlated with soil actinomycetic PLFAs (P = 0.034). After 13 days of incubation, soil F/B showed a positive correlation with the accumulated mineralization (P = 0.004). However, soil microbial community structure(P = 0.014)and total PLFAs(P = 0.033)showed a positive correlation with the accumulated mineralization after 108 days of incubation. Our results indicated that after conversion from paddy soils to drained soils, soil pH and total nitrogen are the key factors regulating the variations in soil microbial community structure and biomass, and then influencing soil organic carbon mineralization.     

水稻种植对黑土微生物生物量和碳源代谢功能的影响

采用磷脂脂肪酸方法和Biolog-ECO微平板检测法,以吉林省长春市双阳区农业技术推广站实验区的土壤为对象,研究了水稻种植对黑土微生物生态结构和功能的影响.结果表明空地中有机质含量最高,其次为田间土,根际土中有机质含量最低;在夏季的样品中有机质含量最高,土壤中全氮的变化趋势与土壤有机质比较相似.土壤微生物群落功能多样性指数则表现为夏季显著高于秋季和春季,春、秋两季差异不明显,冬季最低,空地中微生物群落的Shannon-Wiener指数和Pielou均匀度指数高于田间和根际.全部样品微生物生长步入稳定期时间和碳源的颜色平均变化率变化范围不同,时间分别为216、192、216、120 h,范围分别为0.52~0.84、0.82~1.28、0.40~0.84、0.05~0.48,表明春秋季微生物步入稳定期和对碳源的代谢量比较相似,夏季最大,冬季最小.研究结果为科学评价典型水稻种植黑土区土壤生境质量退化与恢复过程中微生物特征的变化提供参考.     

Gemini1231双季铵盐选择性抑制赤潮生物生长的实验

以甲藻门的东海原甲藻、塔玛亚历山大藻、裸甲藻,黄藻门的赤潮异弯藻,硅藻门的中肋骨条藻等典型赤潮生物以及绿藻门的青岛大扁藻和亚心形扁藻2种非赤潮生物为研究对象,探讨了Gemini1231双季铵盐类表面活性剂的抑藻活性.结果表明,该表面活性剂在较低浓度下(0.2～0.5 mg·L^-1时),对东海原甲藻、塔玛亚历山大藻和赤潮异湾藻等赤潮生物的生长表现出了明显的抑制作用.当该双季铵盐的浓度增至0.5 mg·L^-1以上时,对中肋骨条藻的生长也表现出了一定的抑制作用.而在相同浓度范围内,对裸甲藻和所选用的2种非赤潮生物生长的影响不明显,表现出了抑藻作用的选择性.对各海洋微藻的脂肪酸组成分析表明,该表面活性剂的选择性抑藻作用与不同海洋微藻生物膜的脂肪酸组成,尤其是其多不饱和脂肪酸的含量明显相关.