桂林尧山地区20年生桉树林土壤呼吸昼夜变化特征

以桂林尧山地区20年生桉树林为研究对象,于2013年1—11月,分春、夏、秋和冬4个季节对土壤呼吸速率及环境因子日变化进行24 h的动态监测。结果表明:(1)20年生桉树林土壤呼吸具有明显日变化特征,呈单峰或双峰曲线形式。4季土壤呼吸速率均在17:00—19:00达最大值,在次日05:00—09:00达最小值。白天土壤呼吸速率变化较大,夜间变化较小;(2)4个季节土壤总呼吸速率之间存在显著差异(P0.05),从大到小依次为夏、春、秋和冬季,自养呼吸贡献率从大到小依次为春、冬、夏和秋季;(3)土壤总呼吸、自养呼吸和异养呼吸速率与土壤温度均呈显著正相关关系(P0.01),土壤温度分别可解释土壤总呼吸、自养呼吸和异养呼吸变化的64.18%、15.43%和83.58%;(4)土壤总呼吸、自养呼吸和异养呼吸速率与土壤含水量间呈显著正相关关系(P0.01),土壤含水量在一定范围内对土壤呼吸起促进作用。     

有机磷酸酯对青海弧菌Q67毒性的构效关系

以淡水发光菌Q67为受试生物,结合微孔板高通量检测技术,测定了15种常见有机磷酸酯的毒性,同时选用极化率(P)、分子表面积(TSA)、正辛醇/水分配系数(logD)和芳香环个数(N Ar)等有机磷酸酯的7种分子结构描述符,采用偏最小二乘回归分析方法建立了15种有机磷酸酯对Q67发光菌毒性的定量结构活性相关(quantitative structure-activity relationships,QSAR)模型。结果表明,15种有机磷酸酯的EC50在1.13×10-5~3.27×10-3mol·L-1之间。在7个结构变量中,4个变量发挥主要作用。其中分子极化率(P)在有机磷酸酯类污染物对发光菌的急性毒性中发挥重要作用,推断发光菌中的荧光素酶及其辅酶是其主要作用位点;脂溶性(logD)越大的化合物越较易穿过细胞膜,进而使Q67发光菌的毒性效应增大;芳香环数(N Ar)越多,有机磷酸酯对发光菌的急性毒性越大;对分子结构类似的有机磷酸酯,其Q67发光菌的毒性效应随TSA值的增大而增强。利用所构建的构效关系模型,其稳定性(Q2CUM=0.544)和预测能力(Q2EXT=0.808,RMSE=0.195)较好,可用来预测有机磷酸酯对Q67发光菌的急性效应。     

两相分配生物反应器中苍白杆菌PW对芘的降解效果

为降低PAHs对微生物的毒性,促进PAHs的降解,采用TPPB技术(two-phase patitioning bioreactor,两相分配生物反应器)对芘进行降解,研究了不同有机相(硅油、十二烷、十一醇、癸烷、十六烷、十八烷)、ρ(芘)、φ(有机相)和扰动速率对芘降解的影响. 结果表明:当φ(有机相)为10.0%、ρ(芘)为100~1 000 mg/L时,T0(纯水相)及T1(水-硅油)、T2(水-癸烷)、T3(水-十二烷)、T4(水-十一醇)、T5(水-十六烷)和T6(水-十八烷)体系中芘的降解率分别为92.5%~13.9%、69.3%~20.1%、79.6%~23.3%、81.9%~26.9%、86.7%~28.1%、87.7%~34.1%、89.6%~27.4%. ρ(芘)较低时,TPPB抑制了芘的降解;ρ(芘)较高时,TPPB则能促进芘的降解. 6种有机相中,十六烷对芘降解的促进效果最优. 最优φ(有机相)的确定和ρ(芘)有关,ρ(芘)为200 mg/L时,最优φ(十八烷)、φ(十六烷)、φ(十一醇)分别为5.0%、2.5%和5.0%;ρ(芘)为1 000 mg/L时,其均为20.0%. 液体扰动速率的提高能促进芘的降解,液体扰动速率为50~200 r/min时,T6和T5体系中的芘的降解率分别为50.1%~75.6%和54.1%~79.1%. 研究显示,TPPB技术是一种潜在治理高浓度PAHs污染的有效途径,TPPB的优化是多种影响因素综合作用的结果.      

Effect of phosphorus fluctuation caused by river water dilution in eutrophic lake on competition between blue-green alga Microcystis aeruginosa and diatom Cyclotella sp.

Tega-numa (Lake Tega) is one of the eutrophic lakes in Japan. For the improvement of water quality in Lake Tega, the Northchiba Water Conveyance Channel was constructed in 2000, which transfer water from Tone River into the lake. After 2000, the dominant species of diatoms, mainly Cyclotella sp., have been replacing blue-green algae, mainly Microcystis aeruginosa in Lake Tega. This transition of dominant species would be due to the dilution, but the detail mechanism has not been understood yet. This study examined the relationship between phosphorus fluctuation caused by river water dilution to Lake Tega and dominance of algal species, M. aeruginosa or Cyclotella sp. based on the single-species and the mixed-species culture experiments. The single-species culture experiment showed that the half-saturation constant and uptake rate of phosphorus were one order lower and seven times higher for M. aeruginosa than those for Cyclotella sp. These findings implied that M. aeruginosa would possess a potential for the growth and survival over Cyclotella sp. in the phosphorus limited condition. The superiority of M. aeruginosa was reflected in the outcome of the mixed-species culture experiment, i.e., dominance of M. aeruginosa, even phosphorus concentration was lowered to 0.01 mg-P/L. Therefore, it could be concluded that the decrease in phosphorus concentration due to the river water dilution to Lake Tega would be interpreted as a minor factor for the transition of dominant species from M. aeruginosa to Cyclotella sp.     

Isolation of Cr(Ⅵ) reducing bacteria from industrial effluents and their potential use in bioremediation of chromium containing wastewater

The present study is aimed at assessing the ability of Bacillus sp.JDM-2-1 and Staphylococcus capitis to reduce hexavalent chromium into its trivalent form.Bacillus sp.JDM-2-1 could tolerate Cr(Ⅵ) (4800 μg/mL) and S.capitis could tolerate Cr(Ⅵ) (2800 μg/mL).Both organisms were able to resist Cd2+ (50 μg/mL),Cu2+ (200 μg/mL),Pb2+ (800 μg/mL),Hg2+ (50 μg/mL) and Ni2+ (4000 μg/mL).S.capitis resisted Zn2+ at 700 μg/mL while Bacillus sp.JDM-2-1 only showed resistance up to 50 μg/mL.Bacillus sp.JDM-2-1 and S.capitis showed optimum growth at pH 6 and 7,respectively,while both bacteria showed optimum growth at 37℃.Bacillus sp.JDM-2-1 and S.capitis could reduce 85% and 81% of hexavalent chromium from the medium after 96 h and were also capable of reducing hexavalent chromium 86% and 89%,respectively,from the industrial effluents after 144 h.Cell free extracts of Bacillus sp.JDM-2-1 and S.capitis showed reduction of 83% and 70% at concentration of 10 μg Cr(Ⅵ)/mL,respectively.The presence of an induced protein having molecular weight around 25 kDa in the presence of chromium points out a possible role of this protein in chromium reduction.The bacterial isolates can be exploited for bioremediation of hexavalent chromium containing wastes,since they seem to have the potential to reduce the toxic hexavalent form to its nontoxic trivalent form.     

一株芽孢杆菌及其破乳特性研究

从某油污样品中分离、筛选出一株破乳菌株10#,经鉴定属芽孢杆菌属。该菌株对油田稳定O/W乳化液具明显的破乳效果。该菌株最佳培养条件为:温度30~35℃,pH7.0~7.5,生长时间48~72h,碳源为液体石蜡。该菌株在培养48h后具有明显而稳定的破乳效果,破乳活性部位为菌体。     

Modeling and prediction for the acute toxicity of pesticide mixtures to the freshwater luminescent bacterium Vibrio qinghaiensis sp.-Q67

In China, water pollution by pesticide mixtures has constituted a serious environmental problem due to potential toxicity and bioaccumulation. But few pesticide combinations have exactly similar and dissimilar mechanisms of action. For this purpose, in tests with the freshwater luminescent bacterium (Vibrio qinghaiensis sp.-Q67), ten pesticides, including three herbicides and seven insecticides, were selected as test substances. Concentration response analysis was performed for ten individual substances, an...     

3-PBA降解菌BA3的降解特性及基因工程菌构建

从石油污染土壤中分离到1株能以3-苯氧基苯甲酸(3-PBA)为唯一碳源生长的细菌,命名为BA3.根据其生理生化特征和16S rDNA序列相似性分析,将该菌鉴定为鞘脂菌属(Sphingobium sp.).该菌株在60 h内对100 mg·L-1的3-苯氧基苯甲酸的降解率达到99%.降解3-苯氧基苯甲酸的最适温度为30℃...     

Removal of sulfamethazine antibiotics by aerobic sludge and an isolated Achromobacter sp. S-3

Removal characteristics of sulfamethazine (SMZ) by sludge and a bacterial strain using an aerobic sequence batch reactor (ASBR) were studied. Operating conditions were optimized by varying the reaction time and sludge retention time (SRT). An Achromobacter sp. (S-3) with the ability to remove SMZ was isolated from the ASBR. The effects of different operating parameters (pH and temperature) on the biodegradation of SMZ by S-3 were determined. The results indicate that, between 0.5 and 4 hr, reaction time of the ASBR had a significant effect on the SMZ removal efficiency in the system. The SMZ removal efficiency also increased from 45% to 80% when SRT was prolonged from 5 to 25 days, although longer SRT had no impact on SMZ removal. The SMZ adsorption rate decreased with increasing temperature, which fitted Freundlich isotherm well. The removal of SMZ in the ASBR was due to the combined effects of adsorption and degradation, and degradation played a leading role.     

一株聚丙烯酰胺降解菌降解聚丙烯酰胺及原油性能研究

以聚丙烯酰胺为能源和碳源从油田采出水中分离到一株菌,根据其生理生化特性分析及生长试验,该株菌被鉴定为假单胞菌属PD 1菌株.对该菌的性能进行了评价,证明该菌能够在含原油、聚丙烯酰胺的水环境中生长,并对原油和聚丙烯酰胺具有降解作用.化学分析表明,在细菌的降解下,原油物性发生改变,姥鲛烷 nC17和植烷 nC18以及∑C-22和(C21+21 ∑C+C22)/(C28+C29)的比值明显增加,原油部分分解为丙酸、烯酸、十六烷酸;同时,聚丙烯酰胺的分子结构受到破坏,粘度降低,相对分子量由原来的1×107变为1×105～1×106,分子链上的酰胺基水解成羧基.