Kinetic analysis and bacterium metabolization of α-pinene by a novel identified Pseudomonas sp. strain

Biodegradation has become a popular alternative remediation technology for its economic and ecological advantages. An aerobic bacterium (strain ZW) capable of degrading αup-pinene was isolated from a biofilter by a selective enrichment. Based on the 16S rRNA gene analysis and physiochemical properties, this strain was identified as Pseudomonas veronii. Under the optimized condition achieved by the response surface methodology (RSM), as well as pH 6.82, temperature 26.3\textcelsius and NaCl concentration 1.36%, almost 100% αup-pinene could be removed within 45 hr. Enzymatic biodegradation by the crude intracellular enzyme could be described well by the Michaelis-Menten model in which the maximum degradation rate V_max and the half-saturation constant K_m were calculated to be 0.431 mmol/(L. min) and 0.169 mmol/L, respectively. Activity assay of catechol suggested that the strain ZW possessed a catechol-1,2-dioxygenase and could decompose benzene-ring through ortho ring cleavage. Based on the identified intermediates by GC/MS, a new metabolic pathway was proposed, in which the final metabolites were some simpler organic and inorganic compounds. The present work demonstrated that the strain ZW would have a great application prospect for the remediation of αup-pinene-contaminated environment.     

Replacement males in the western bluebird: opportunity for paternity, chick-feeding rules, and fitness consequences of male parental care

In western bluebirds (Sialia mexicana), most pairs remain together for life and share equally in post-hatching parental care. We removed resident males of socially monogamous pairs during laying and after clutch completion to examine chick-feeding rules used by replacement males and current and future fitness consequences of paternal care. Replacement males were not infanticidal and 7 (47%) fed nestlings. Feeding replacement males and the females they joined fed at rates similar to controls. Females without a feeding replacement male compensated by feeding more themselves so that overall feeding rates were not compromised, but they reduced their brooding time. Unlike assisted females, unassisted females exhibited reduced nesting success and their 14-day-old chicks weighed less than controls. Field metabolic rates of unassisted females were 17% higher than those of control females, but the difference was not statistically significant. Older females were better able to raise young without the male's help than were yearling females. Female condition was not affected by male provisioning and unassisted females were as likely to survive to the next breeding season as assisted females. We found no future benefits of provisioning by replacement males; those that fed were no more likely to breed with the female on her subsequent attempt than were males that did not feed, and subsequent clutch sizes were not reduced for females rearing young without the male's help. These experiments suggest that male parental care increases nesting success in western bluebirds and that replacement males use an all-or-none rule to determine whether or not to feed chicks: if they are present during the fertile period they feed at typical rates; if they are not, they usually do not feed at all. Because chick-feeding by males is tied to opportunity for paternity, influences success in the current nest, and does not affect the male's future breeding success, it appears to be parental rather than mating effort. Received: 8 May 1998 / Accepted after revision: 23 July 1998     

苯并［a］芘对黑鲷肝脏GST活性的影响及其与肝脏代谢酶和胆汁代谢产物之间的变化关系

为探讨苯并[a]芘(B[a]P)暴露对鱼类的影响并筛选特异、敏感的生物标志物,研究了B[a]P对黑鲷(Sparus macrocephalus)肝脏谷胱甘肽-S-转移酶(GST)活性的影响,并分析了肝脏7-乙氧基异吩唑酮-脱乙基酶(EROD)、GST活性与胆汁中B[a]P典型代谢产物3-羟基-苯并[a]芘(3-OHB[a]P)3者之间及与B[a]P之间的剂量、时间-效应关系.结果显示:在B[a]P(0.5、1.0、2.0和5.0μg·L-1)暴露期间,肝脏GST活性随暴露时间总体呈"钟"形的变化趋势,在第2d时达到峰值;在第12h、1d和2d时,GST活性与B[a]P暴露浓度呈显著正相关(R12h=0.966(p<0.05)、R1d=0.953(p<0.05)、R2d=0.824(p<0.05)).与前期研究结果对比分析发现,B[a]P(0.5、1.0、2.0和5.0μg·L-1)暴露7d时,胆汁中3-OHB[a]P浓度与B[a]P暴露浓度呈显著的剂量-效应关系(R=0.943,p<0.05);黑鲷肝脏GST、EROD活性与3-OHB[a]P的对数浓度均呈显著正相关(RGST=0.740(p<0.05)、REROD=0.839(p<0.05));2.0μg·L-1B[a]P暴露后,黑鲷肝脏EROD、GST活性与3-OHB[a]P随暴露时间的变化趋势基本相同,但并不完全一致.鱼类肝脏EROD、GST与胆汁中B[a]P代谢产物3者之间的变化关系较为复杂,暴露浓度和时间是影响其变化的重要因素,肝脏GST和EROD活性比胆汁中代谢产物更易受其影响,在B[a]P的环境监测中代谢产物可能是一种更为可行的生物标志物.     

Interactive effects of cadmium and hypoxia on metabolic responses and bacterial loads of eastern oysters Crassostrea virginica Gmelin

Pollution by toxic metals including cadmium (Cd) and hypoxia are important stressors in estuaries and coastal waters which may interactively affect sessile benthic organisms, such as oysters. We studied metabolic responses to prolonged hypoxic acclimation (2 weeks at 5% O₂) in control and Cd-exposed (30 d at 50 μg L⁻¹ Cd) oysters Crassostrea virginica, and analyzed the effects of these stressors on abundance of Vibrio spp. in oysters. Hypoxia-acclimated oysters retained normal standard metabolic rates (SMR) at 5% O₂, in contrast to a decline of SMR observed during acute hypoxia. However, oysters spent more time actively ventilating in hypoxia than normoxia resulting in enhanced Cd uptake and 2.7-fold higher tissue Cd burdens in hypoxia. Cd exposure led to a significant decrease in tissue glycogen stores, increase in free glucose levels and elevated activity of glycolytic enzymes (hexokinase and aldolase) indicating a greater dependence on carbohydrate catabolism. A compensatory increase in activities of two key mitochondrial enzymes (citrate synthase and cytochrome c oxidase) was found during prolonged hypoxia in control oysters but suppressed in Cd-exposed ones. Cd exposure also resulted in a significant increase in abundance of Vibrio parahaemolyticus and Vibrio vulnificus levels during normoxia and hypoxia, respectively. Overall, Cd- and hypoxia-induced changes in metabolic profile, Cd accumulation and bacterial flora of oysters indicate that these stressors can synergistically impact energy homeostasis, performance and survival of oysters in polluted estuaries and have significant consequences for transfer of Cd and bacterial pathogens to the higher levels of the food chain.     

Toxic effects of four sulphonylureas herbicides on soil microbial biomass

The effect of four triazinyl-sulfonylurea herbicides (cinosulfuron, prosulfuron, thifensulfuron methyl, triasulfuron) on soil microbial biomass, soil respiration, metabolic activity, metabolic quotient, and some enzymatic activities (acid and alkaline phosphatase, β-glucosidase, arylsulphatase, and fluorescein diacetate hydrolysis) were monitored under controlled conditions over 30 days. The herbicides were applied at the normal field dose (FD) and at ten-fold (10 FD) the field dose, in order to mimic a long term toxic effect. The measured soil microbial parameters showed that the FD had slight effects on soil microflora, while at 10 FD the tested herbicides exerted a stronger detrimental effect on soil microbial biomass and its biochemical activities.     

基于物质流分析的密云水库上游流域磷循环特征

运用物质流分析方法,对北京市地表饮用水源地--密云水库流域进行了磷循环特征的研究;分析了研究区域内种植业、畜牧业、人口和简单子系统内部及子系统间的磷输入输出状况,以及系统整体的代谢效率特征,讨论了流域水体磷污染负荷的影响因素.研究结果表明:①化肥、饲料添加剂和农药是流域磷输入的主要来源,占直接物质磷输入总量的52.9%;整个系统向环境输入磷2868.44t,其中的26.5%直接进入水体.②在水体磷负荷中,畜牧业系统的贡献最大,为1800.26 t,达到输出总量的82%,其次为种植业系统,占9.4%.③系统整体结构不协调.呈现单向和开放状态.研究区种植业系统运行出现磷亏缺,并具有区域性和不均衡性的特点;而畜牧业系统则出现磷盈余,整体结构不协调;畜禽的排泄物未能得到有效处置和循环再生,其中进入水体的量占畜禽粪尿磷总量的40.9%,从而造成严重的资源浪费和广泛的生态环境影响.④水体污染负荷与城市化率密切相关.     

一株Diaphorobacter属细菌对苯酚的降解特性和代谢途径

Diaphorobacter sp.ZW12菌株具有较高的苯酚耐受性和降解能力,通过摇瓶培养在以苯酚为唯一碳源的基本培养基中考察该菌株对苯酚的耐受性和苯酚降解特性。结果表明,该菌株能在苯酚浓度为4.0g/L的培养基中生长,完全降解苯酚的最高浓度可达3.0g/L。其最适生长pH、生长温度和代谢温度分别是pH7.0、33℃和30℃。利用苯酚羟化酶基因(Lph)、邻苯二酚-1,2-加氧酶基因(C12O)和邻苯二酚-2,3-加氧酶基因(C23O)特异性引物对ZW12总DNA进行PCR扩增,结果Lph基因和C23O基因PCR扩增阳性、C12O基因扩增呈阴性,表明ZW12对苯酚的代谢是通过C23O途径进行的。     

Microbial community characterization, activity analysis and purifying efficiency in a biofilter process

The growth and metabolism of microbial communities on biologically activated carbon(BAC) play a crucial role in the purification of drinking water.To gain insight into the growth and metabolic characteristics of microbial communities and the efficiency of drinking water treatment in a BAC filter,we analyzed the heterotrophic plate count(HPC),phospholipid,dehydrogenase,metabolic function and water quality parameters during start-up and steady-state periods.In the start-up process of the filter with natural biofilm colonization,the variation in heterotrophic plate count levels was S-curved.The total phospholipid level was very low during the first 5 days and reached a maximum value after 40 days in the filter.The activity of dehydrogenase gradually increased during the first 30 days and then reached a plateau.The functional diversity of the microbial community in the filter increased,and then reached a relatively stable level by day 40.After an initial decrease,which was followed by an increase,the removal rate of NH4+-N and COD Mn became stable and was 80% and 28%,respectively,by day 40.The consumption rate of dissolved oxygen reached a steady level after 29 days,and remained at 18%.At the steady operation state,the levels of HPC,phospholipid,dehydrogenase activity and carbon source utilization had no significant differences after 6 months compared to levels measured on day 40.The filter was shown to be effective in removing NH4+-N,NO2--N,COD Mn,UV 254,biodegradable dissolved organic carbon and trace organic pollutants from the influent.Our results suggest that understanding changes in the growth and metabolism of microorganisms in BAC filter could help to improve the efficiency of biological treatment of drinking water.     

过量氮输入对寡营养海水细菌群落代谢潜力的影响

细菌在海洋氮循环中起关键作用,而过量氮输入对细菌群落代谢潜力的影响还未被充分阐明.本研究通过构建3组寡营养海水生态微宇宙,包括对照组、一次性输入组(一次性输入硝酸盐使体系中硝氮浓度为1.0 mg·L-1)和连续性输入组(每隔2 d输入一次硝酸盐,使体系中硝氮浓度每次增加0.125 mg·L-1,直至与一次性输入组达到相同水平),利用Biolog-Eco板技术和16S rDNA PICRUSt(Phylogenetic investigation of communities by reconstruction of unobserved states)功能基因预测,研究过量氮输入下细菌群落代谢潜力的动态变化.结果表明,实验第16 d,氮的连续性输入提高了细菌群落的碳源利用能力,对照和连续性输入组中碳源利用特征随采样时间发生了显著变化.此外,预测到的功能基因家族组成随时间明显变化,并与亚硝酸盐、铵盐、磷酸盐、化学需氧量、溶解氧、pH和总磷密切相关,固氮、异化硝酸盐还原、反硝化、异化硝酸盐还原到铵和同化硝酸盐还原相关基因的相对丰度受到了氮输入的影响,而氮连续输入导致的氮代谢相关基因变化较一次性输入更为普遍.本研究初步揭示了过量氮输入对寡营养海水细菌群落代谢潜力的影响,为探明近岸海域过量氮输入的微生态效应提供了基础数据.     

双SBR脱氮除磷工艺的数学模型分析

应用ASM2和Delft代谢模型,结合双SBR(A2-SBR)脱氮除磷系统的特点,建立了数学模拟器,并将其运用于双SBR脱氮除磷系统运行特性的动力学分析.主要探讨了不同泥龄、碳氮比、碳磷比对系统的影响,并从模型的角度进行了分析.结果表明,利用ASM2和Delft代谢模型结合所建立的数学模拟器可以对双SBR(A2-SBR)脱氮除磷系统进行模拟.双SBR中具有脱氮除磷功能的A2-SBR的运行参数是关键因素,最佳污泥龄为9～12d时,碳氮比为3.75左右,碳磷比大于15条件下,双SBR运行正常,能得到较好的处理效果.当系统在泥龄大于12d条件下运行时,由于PAO储存了大量的聚合态磷(XPP/XPAO接近0.5)造成除磷效率降低.同样的原因也导致了碳磷比值低于15时,PAO的聚磷反应变慢或停止.