首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 62 毫秒
1.
微生物降解蔬菜残留农药研究   总被引:36,自引:2,他引:34  
从富集培养物中筛选到以甲胺磷为唯一碳源生长的菌株NMJ5和以乐果为唯一碳源生长的菌株NML3,经鉴定分别为芽孢杆菌属(Bacilussp.)和假单胞菌属(Pseudomonassp.).它们利用甲胺磷、乐果生长的最适条件及在无机盐培养基中农药最大耐受浓度分别为pH7.5,t=35℃,ρ=1000mg/L和pH7.5,t=30℃,ρ=2000mg/L.在无碳基础培养基内单菌株培养8d,524mg/L的甲胺磷好气降解42.5%,厌气降解35.9%,250mg/L的乐果好气降解50.2%,厌气降解16.4%.小区试验表明,NMJ5、NML3的菌液制剂对普通白菜的变种南农矮脚黄(Brasicacampestrissp.chinensisL.var.communisTsenetLee)中残留的甲胺磷、乐果有明显的去除作用.  相似文献   

2.
微生物降解苯胺的特性及其降解代谢途径   总被引:7,自引:0,他引:7  
从活性污泥中分离得到的一株细菌 A N3 ,能以苯胺为唯一碳、氮源和能源生长,苯胺的最高降解浓度5000 mg/ L 以上,鉴定为食酸丛毛单胞菌( Comamonas acidovorans) . A N3 还可降解乙酰苯胺,但不利用其他取代类苯胺,该菌株的生长细胞和完整细胞降解苯胺的最适p H7 .0 ,最适温度30 ℃,且完整细胞降解苯胺的活性比生长细胞高得多.9 种金属离子对该菌株的生长细胞和完整细胞降解苯胺均有不同程度的抑制作用,尤以 Ag + 和 Hg2 + 为明显. A N3 含有苯胺加双氧酶、邻苯二酚2 ,3加双氧酶等一系列与苯胺降解有关的酶类,它们均为诱导酶.对苯胺降解的关键酶进行了酶动力学特性的研究,根据这些结果提出了该菌株降解苯胺的代谢途径.  相似文献   

3.
农药降解酶的固定化及其降解特性   总被引:11,自引:0,他引:11  
采用海藻酸钙凝胶将 Alcaligenes sp . Y F11 农药降解酶进行固定化,并测定了固定化酶对杀灭菊酯的降解特性. 农药降解酶的固定化条件为:海藻酸钠质量浓度,30 g/ L;蛋白质量浓度,0 .2 g/ L;固定化时间t = 16h ;粒径4 mm . 固定化酶降解杀灭菊酯的最适p H 为8 .0 、最适温度为35 ℃, Km55 .0 μmol/ L  相似文献   

4.
食酸丛毛单胞菌AN3菌株降解苯胺的研究   总被引:3,自引:0,他引:3  
报道了各种环境因子对食酸丛毛单胞菌AN3菌株完整细胞降解苯胺的影响.在良好的通气条件下,该菌株完整细胞降解苯胺,最适湿细胞质量浓度ρFW(cel)=20g/L、最适pH和温度θ分别为7.0和30℃,苯胺ρ=1300mg/L左右,经过6h的作用即可被完全降解;各种有机物如葡萄糖和蛋白胨对苯胺的降解均有延缓的作用:除Hg2+和Ag+外,其他重金属离子对苯胺降解抑制作用较小  相似文献   

5.
不同菌源的微生物对邻苯二甲酸二甲酯生物降解性的比较   总被引:2,自引:0,他引:2  
从处理石化厂废水的活性污泥中分离出1 株邻苯二甲酸酯降解菌 F S1( 荧光假单胞菌 Pseudomonasfluorescens F S1) ,从处理焦化厂废水的活性污泥中分离出2 株邻苯二甲酸酯降解菌 F S2( 铜绿假单胞菌 Pseudomonasaeruginasa F S2) 和 F S3( 短杆菌 Brevibacterium sp . F S3) . 研究了邻苯二甲酸酯降解菌 F S1 , F S2 和 F S3 对邻苯二甲酸二甲酯( D M P) 的最适降解条件,比较了其降解特性. F S1 、 F S2 和 F S3 最适酸度分别为p H6 .5 ~8 .0 、p H7 .0 ~8 .0 和p H7 .0 ~8 .0 ,温度为20 ~35 ℃、15 ~35 ℃和15 ~35 ℃.邻苯二甲酸酯降解菌 F S1 、 F S2 和 F S3 对邻苯二甲酸二甲酯的降解的半寿期: F S1 < F S2 < F S3 ,邻苯二甲酸酯降解菌 F S1 是一株高效的邻苯二甲酸二甲酯降解菌  相似文献   

6.
利用动胶菌D2菌株处理含油废水的中间试验研究   总被引:1,自引:0,他引:1  
利用自行分离筛选的动胶菌( Zoogloea sp .) D2 菌株以生物接触氧化法对含机械润滑油的废水进行处理.在实验室条件下,控制入流流量qv = 33 L/h ,t H R= 6 h ,除油效果十分显著:当废水的含油浓度为424 ~1 432mg/ L时,经过试验运转,出流水中油浓度已降至0 ~20 mg/ L,除油率达97 % 以上,水质达到国家二级以上的排放标准  相似文献   

7.
丁草胺高效降解细菌的分离   总被引:12,自引:0,他引:12  
通过瓶培养法富集培养,从肥东县一块单晚稻田土中分离出一株丁草胺高效降解细菌WY306,经鉴定,该菌为节杆菌属菌Arthrobacter sp.WY306.Arthrobacter sp.WY306降解丁草胺的影响因素研究表明:丁草胺降解半衰期与初始菌量近似成反比;当丁草胺添加浓度为5、9mg/L时,其降解半衰期分别为0.97h和1.86h,随浓度的增大而增大,而当丁草胺添加浓度为0.8mg/L或其  相似文献   

8.
青霉菌BS-1生长时还原Cr^6+的条件下:最适碳源为蔗糖或糊精,最适氮源是硫酸铵,最适温度30℃,最适PH7.0,加入一定浓度的酵母浸出物可促进该菌对Cr^+的还原。不同预培养条件对该菌还原Cr^6+无明显影响,由此认为该菌对Cr^6+的还原是非诱导性的Hg^2+,Cu^2+,Co^2+和Ni^2+对BS-1生长及Cr^2|还在有明显抑制作用,但在ρ(Na2SeO4)=100mg/L时,则对该菌  相似文献   

9.
用分离获得的嗜热厌氧纤维素降解细菌 Clostridium sp . E V A4 菌株进行了直接转化纤维素产生乙醇的动力学、发酵最适条件及其影响因子的研究.结果表明, E V A4 菌株在p H6 .2 ~8 .9 ,θ45 ℃~60 ℃的范围内能直接转化纤维素滤纸产生乙醇,最适p H 为7 .5 ~8 .0 ,最适θ为55 ~60 ℃. E V A4 菌株能利用纤维素滤纸,纤维素粉 Whatman C F I I,微晶纤维素,纤维素粉 M N300 和未经处理的玉米秆芯,甘蔗渣,水稻秸秆产生乙醇.乙醇浓度 ,纤维素降解率和培养基还原糖浓度均随培养时间延长而增大.不同的纤维素材料、p H、θ、底物浓度、酵母粉含量、振荡、培养气相、外加 O2 和乙醇等条件均能影响 E V A4 菌株转化纤维素为乙醇的能力.最适条件下 E V A4 菌株利用1 % 纤维素滤纸培养120 h 产乙醇浓度为1 123 mg/ L,纤维素降解率为59 %  相似文献   

10.
用从土壤中筛选的假单胞菌(Pseudomonassp.)E4106株细胞进行了转化苯丙酮酸生产L苯丙氨酸实验研究.结果表明,转氨反应最适温度35~40℃;该转氨酶可在pH7~10范围内催化反应而活力变化不大;0.5%戊二醛处理细胞可降低其转氨酶活力;表面活性剂处理细胞或在反应液中加入Mg2+能显著提高转氨反应速度;L天冬氨酸是转氨反应的最适氨基供体;底物转化率与底物浓度、氨基供体浓度有关.在此反应体系中,E4106菌株单位湿重细胞的转氨酶活力为1039U/g;生成产物LPhe浓度为32.2g/L和50.4g/L时,苯丙酮酸摩尔转化率分别为97.5%、87.2%.生成产物用CGA688大孔吸附树脂进行分离、纯化.目标产物经熔点、比旋光度、元素分析、红外光谱和纸层析分析,证实是LPhe.产物收率为81.8%.  相似文献   

11.
A bioblitz inexpensively and quickly generates biodiversity data, but bioblitzes are often conducted with haphazard, unreplicated sampling. Results tend to be taxonomically, geographically, or temporally biased, lack metadata, and consist of lists of observed taxa that do not enable further analyses or correction for imperfect detection. A rapid, recurring, structured survey (RRSS) uses a structured sampling design and temporal and spatial replication to survey randomly selected sites on a conservation property. We participated in a loosely structured bioblitz and a subsequent RRSS at Big Canoe Creek Nature Preserve in Springville (St. Clair County), Alabama (USA) to compare observed richness derived from the 2 survey approaches. The RRSS data structure enabled us to fit models that accounted for imperfect detection to estimate abundances, occupancy probabilities, and habitat associations. The loosely structured bioblitz data could not be used in such models. We present a new integrated multispecies abundance model that we applied to avian RRSS data. Our model extension enables estimation for the community, employs data augmentation to estimate the number of undetected species, and incorporates covariates. The RRSS generated a more comprehensive and less biased list of observed taxonomic richness than the loosely structured bioblitz (e.g., 73 vs. 45 bird species and 104 vs. 63 insect families from the RRSS vs. loosely structured bioblitz, respectively). Models fit to the RRSS data identified seasonal patterns in avian community composition and allowed for estimation of habitat–occupancy relationships for insect taxa. The RRSS protocol has potential for broad transferability as a standardized, quick, and inexpensive way to inventory biodiversity and estimate ecological parameters while providing an outreach opportunity.  相似文献   

12.
Land-use change via human development is a major driver of biodiversity loss. To reduce these impacts, billions of dollars are spent on biodiversity offsets. However, studies evaluating offset project effectiveness that examine components such as the overall compliance and function of projects remain rare. We reviewed 577 offsetting projects in freshwater ecosystems that included the metrics project size, type of aquatic system (e.g., wetland and creek), offsetting measure (e.g., enhancement, restoration, and creation), and an assessment of the projects’ compliance and functional success. Project information was obtained from scientific and government databases and gray literature. Despite considerable investment in offsetting projects, crucial problems persisted. Although compliance and function were related to each other, a high level of compliance did not guarantee a high degree of function. However, large projects relative to area had better function than small projects. Function improved when projects targeted productivity or specific ecosystem features and when multiple complementary management targets were in place. Restorative measures were more likely to achieve targets than creating entirely new ecosystems. Altogether the relationships we found highlight specific ecological processes that may help improve offsetting outcomes.  相似文献   

13.
An argument is presented in which areas of natural arsenic contamination of modern groundwaters throughout Asia have a common origin. Arsenic originally accumulated in oceanic ferro-manganoan sediments of the eastern Palaeo-Tethys. This was further concentrated through oceanic crustal extinction in what later became the south-east Chinese accreted mineralised terrain. Proto-Himalayan uplift of this area created the palaeo-drainage systems of the Ganges – Brahmaputra, Irrawaddy, Mekong, and Red Rivers, with consequent headwater erosion of arsenic-rich sediments. Their downstream deposition as immature and easily redistributed Neogene sandstones, silts, and iron-rich clays has created secondary and tertiary reservoirs of adsorbed and authigenic arsenic, from which the current arsenic-rich groundwaters have evolved. Considering river basins within the above palaeo-hydrogeological framework provides a basis for assessing the risk of arsenic in groundwater basins of south and south-eastern Asia.  相似文献   

14.
How should managers choose among conservation options when resources are scarce and there is uncertainty regarding the effectiveness of actions? Well‐developed tools exist for prioritizing areas for one‐time and binary actions (e.g., protect vs. not protect), but methods for prioritizing incremental or ongoing actions (such as habitat creation and maintenance) remain uncommon. We devised an approach that combines metapopulation viability and cost‐effectiveness analyses to select among alternative conservation actions while accounting for uncertainty. In our study, cost‐effectiveness is the ratio between the benefit of an action and its economic cost, where benefit is the change in metapopulation viability. We applied the approach to the case of the endangered growling grass frog (Litoria raniformis), which is threatened by urban development. We extended a Bayesian model to predict metapopulation viability under 9 urbanization and management scenarios and incorporated the full probability distribution of possible outcomes for each scenario into the cost‐effectiveness analysis. This allowed us to discern between cost‐effective alternatives that were robust to uncertainty and those with a relatively high risk of failure. We found a relatively high risk of extinction following urbanization if the only action was reservation of core habitat; habitat creation actions performed better than enhancement actions; and cost‐effectiveness ranking changed depending on the consideration of uncertainty. Our results suggest that creation and maintenance of wetlands dedicated to L. raniformis is the only cost‐effective action likely to result in a sufficiently low risk of extinction. To our knowledge we are the first study to use Bayesian metapopulation viability analysis to explicitly incorporate parametric and demographic uncertainty into a cost‐effective evaluation of conservation actions. The approach offers guidance to decision makers aiming to achieve cost‐effective conservation under uncertainty.  相似文献   

15.
Parasitic wasps orient to green leaf volatiles   总被引:12,自引:0,他引:12  
Summary Undamaged plants emit low levels of green leaf volatiles (GLVs), while caterpillar-damaged and artificially damaged plants emit relatively higher levels of certain GLVs. Female braconid parasitoids,Microplitis croceipes, oriented to both damaged plants and to individual GLVs in no-choice tests in a wind tunnel, but seldom oriented to undamaged plants. Female ichneumonid parasitoids,Netelia heroica, also oriented to individual GLVs in a wind tunnel. Males of both wasp species failed to orient to the GLVs. These data show that leaf-feeding caterpillars can cause the release of GLVs, and that parasitic wasps can respond to these odors by flying upwind (chemoanemotactic response), which brings the wasps to their caterpillar hosts. This supports the hypothesis that plants communicate with members of the third trophic level,i.e., plants under herbivore attack emit chemical signals that guide natural enemies of herbivores to sites of plant damage. In this interaction, the GLVs serve as tritrophic plant-to-parasitoid synomones. That parasitoids from two different wasp families oriented to GLVs suggests that the response may be widespread among the Hymenoptera.Mention of a commercial or proprietary product does not constitute an endorsement by the U.S. Department of Agriculture  相似文献   

16.
Atlantic sturgeon (Acipenser oxyrhynchus) populations have been declared either endangered or threatened under the U.S. Endangered Species Act. Effective measures to repel sturgeon from fishing gear would be beneficial to both fish and fishers because they could reduce both fishery‐associated mortality and the need for seasonal and area closures of specific fisheries. Some chondrostean fishes (e.g., sturgeons and paddlefishes) can detect weak electric field gradients (possibly as low as 5 Μv/cm) due to arrays of electroreceptors (ampullae of Lorenzini) on their snout and gill covers. Weak electric fields, such as those produced by electropositive metals (typically mixtures of the lanthanide elements), could therefore potentially be used as a deterrent. To test this idea, we recorded the behavioral responses of juvenile Atlantic sturgeon (31–43 cm fork length) to electropositive metal (primarily a mixture of the lanthanide elements neodymium and praseodymium) both in the presence and absence of food stimuli. Trials were conducted in an approximately 2.5 m diameter × 0.3 m deep tank, and fish behaviors were recorded with an overhead digital video camera. Video records were subsequently digitized (x, y coordinate system), the distance between the fish and the electropositive metal calculated, and data summarized by compiling frequency distributions with 5‐cm bins. Juvenile sturgeon showed clear avoidance of electropositive metal but only when food was present. On the basis of our results, we conclude that the electropositive metals, or other sources of weak electric fields, may eventually be used to reduce the interactions of Atlantic sturgeon with fishing gear, but further investigation is needed. El Potencial del Metal Electropositivo para Reducir las Interacciones del Esturión Atlántico con Instrumentos de Pesca Bouyoucos, Bushnell & Brill 13–003  相似文献   

17.
Many conservation actions are justified on the basis of managing biodiversity. Biodiversity, in terms of species richness, is largely the product of rare species. This is problematic because the intensity of sampling needed to characterize communities and patterns of rarity or to justify the use of surrogates has biased sampling in favor of space over time. However, environmental fluctuations interacting with community dynamics lead to temporal variations in where and when species occur, potentially affecting conservation planning by generating uncertainty about results of species distribution modeling (including range determinations), selection of surrogates for biodiversity, and the proportion of biodiversity composed of rare species. To have confidence in the evidence base for conservation actions, one must consider whether temporal replication is necessary to produce broad inferences. Using approximately 20 years of macrofaunal data from tidal flats in 2 harbors, we explored variation in the identity of rare, common, restricted range, and widespread species over time and space. Over time, rare taxa were more likely to increase in abundance or occurrence than to remain rare or disappear and to exhibit temporal patterns in their occurrence. Space–time congruency in ranges (i.e., spatially widespread taxa were also temporally widespread) was observed only where samples were collected across an environmental gradient. Fifteen percent of the taxa in both harbors changed over time from having spatially restricted ranges to having widespread ranges. Our findings suggest that rare species can provide stability against environmental change, because the majority of species were not random transients, but that selection of biodiversity surrogates requires temporal validation. Rarity needs to be considered both spatially and temporally, as species that occur randomly over time are likely to play a different role in ecosystem functioning than those exhibiting temporal structure (e.g., seasonality). Moreover, temporal structure offers the opportunity to place management and conservation activities within windows of maximum opportunity.  相似文献   

18.
Summary. Myrmecophytic plants use obligate ant mutualists as a constitutive indirect defence mechanism. These plants often produce cellular food bodies (FBs) to nourish their resident ants. Lipids, proteins, and even highly specialised compounds such as glycogen have been reported from FBs, but detailed chemical analyses of FB composition have so far been presented only for Southeast Asian Macaranga and Central American Piper myrmecophytes. Here we report the chemical composition of FBs of five myrmecophytic Acacia (Fabaceae) species from Mexico using HPLC (carbohydrates and proteins) and GC-MS (lipids). Feeding experiments revealed no hints on any use of external food sources by the inhabiting Pseudomyrmex ants. These ants obviously rely completely on FBs and extrafloral nectar provided by their hosts. The total content of nutrients in Acacia FBs was 15-25% of FB dry mass, being much lower than in Macaranga or Piper FBs. Proteins were dominating (8-14 % dm) in Acacia FBs and thus were present in higher amounts than in Macaranga FBs, yet in lower amounts than in Piper. Lipids contributed 1-9 % of dry mass, showing a lower proportion than in FBs of Macaranga or Piper. Carbohydrates made up 3-11 % dm, reaching in most Acacia species the same range as observed in Macaranga and in Piper FBs. Water content was 18-24 % of FB fresh mass, and structural tissue obviously made up a much higher proportion in Acacia FBs than in Macaranga or Piper FBs. Both characters might represent an adaptation to producing FBs unprotected at the leaf tips under dry conditions. Acacia FBs contain all amino acids and all fatty acids that are considered essential for insects, and their contents of lipids and proteins are higher than in the leaves from which they are ontogenetically derived. This indicates a putatively adaptive enrichment of nutritionally valuable compounds in structures functioning as ant-food.  相似文献   

19.
Conservation biologists are generally united in efforts to curtail the spread of non‐native species globally. However, the colonization history of a species is not always certain, and whether a species is considered non‐native or native depends on the conservation benchmark. Such ambiguities have led to inconsistent management. Within the Tongass National Forest of Alaska, the status of American marten (Martes americana) on the largest, most biologically diverse and deforested island, Prince of Wales (POW), is unclear. Ten martens were released to POW in the early 1930s, and it was generally believed to be the founding event, although this has been questioned. The uncertainty surrounding when and how martens colonized POW complicates management, especially because martens were selected as a design species for the Tongass. To explore the history of martens of POW we reviewed other plausible routes of colonization; genetically and isotopically analyzed putative marten fossils deposited in the late Pleistocene and early Holocene to verify marten occupancy of POW; and used contemporary genetic data from martens on POW and the mainland in coalescent simulations to identify the probable source of the present‐day marten population on POW. We found evidence for multiple routes of colonization by forest‐associated mammals beginning in the Holocene, which were likely used by American martens to naturally colonize POW. Although we cannot rule out human‐assisted movement of martens by Alaskan Natives or fur trappers, we suggest that martens be managed for persistence on POW. More generally, our findings illustrate the difficulty of labeling species as non‐native or native, even when genetic and paleo‐ecological data are available, and support the notion that community resilience or species invasiveness should be prioritized when making management decisions rather than more subjective and less certain conservation benchmarks.  相似文献   

20.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号