外源降解菌对黄麻根区净化能力的生物强化作用

通过原生质体电融合得到经EGFP标记的外源细菌(蒽高效降解菌An和表面活性剂产生菌P)与黄麻根际优势菌融合的2株融合子Tu-An与融合子Tu-P,然后将两种融合子以及出发菌株分别定殖到播种了黄麻(Corchoruscapsulari)的蒽污染土壤中,对不同污染物浓度下的细菌定殖、植物生长及蒽降解做了初步研究.研究表明,在相同的初始接种量下,融合子的定殖数量明显高于出发菌株;在两种融合子共存的条件下,定殖数量也略高于单一融合子的定殖数量.在接种外源菌的土壤中,植物获得了更好的生长条件,得以良好生长;而没有投加降解菌的组别中,黄麻的生长明显受到了较严重的抑制.投加外源降解菌可以促进生物降解,达到生物强化的目的.实验研究说明,把外源降解菌投加到污染土壤中进行生物强化修复是可行的.图3表2参20     

luxAB基因标记甲基对硫磷降解菌DLL-1在土壤和植株根部的生态行为研究

发光酶标记是 1种有效的跟踪微生物在生态环境中动态行为的技术手段。采用luxAB基因标记技术对甲基对硫磷降解菌DLL - 1在土壤中的分布和植株内的定殖情况进行了研究。结果表明 ,DLL - 1可以较长时间的在植株根际定殖 ,3 0d后仍可用X -感光片检测到菌体的存在 ,而根际外未检测到DLL - 1。植株根剖开后在培养基上培养 2 4h后进行X -光片曝光 ,发现DLL - 1能够进入植株根内并定殖。菌株回收后采用测定其农药降解活力和检查质粒图谱 2种方法证实 ,所观测的回收菌株就是接种的DLL - 1菌株     

luxAB基因标记甲基对硫磷降解菌DLL—1在土壤和植株根部的生态行为研究

发光酶标记是1种有效的跟踪微生物在生态环境中动态行为的技术手段。采用luxAB基因标记技术对甲基对硫磷降解菌DLL-1在土壤中的分布和植株内的定殖情况进行了研究。结果表明，DLL-1可以较长时间的在植株根际定殖，30d后仍可用X-感光片检测到菌体的存在，而根际外未检测到DLL-1。植株根剖开后在培养基上培养24h后进行X-光片曝光，发现DLL-1能够进入植株内并定殖。菌株回收后采用测定其农药降解活力和检查质粒图谱2种方法证实，所观测的回收菌株就是接种的DLL-1菌株。     

3株芽孢杆菌在水稻根际定殖促生及其在土壤中的存活

植物根际促生菌(PGPR)可分泌植物生长激素,促进土壤养分循环,是生物肥料重要的种质资源。PGPR吸附于作物根系是形成定殖与功能的必要条件,抗性药物标记是研究功能菌株定殖促生能力的一种手段。利用解钾功能菌(Bacillus aryabhattai LZP01,简称LZP01)、解磷功能菌(Bacillus pumilus LZP02,简称LZP02)和溶磷功能菌(Bacillus megaterium LZP03,简称LZP03)这3株高效的水稻根际促生菌,通过抗生素药物利福平梯度筛选分别得到标记菌株K-LZP01、K-LZP02和K-LZP03,并且研究标记菌株的功能保留情况,进而检测标记菌株在水稻根际与土壤中定殖存活及促生能力。结果表明,水稻幼根浸入菌液后吸附量随浸入时间的增加而增大,其中K-LZP01在10min后吸附基本稳定;K-LZP01在50 min时吸附量达到最大;K-LZP03在5 min时吸附量达到最大,最大吸附量为12×10~7CFU·g~(-1),之后趋于动态稳定。将水稻幼苗浸入不同浓度菌悬液中,幼根吸附量随菌悬液浓度的增大而增大。标记菌株在接种于土壤中10 d后定殖量趋于稳定,且定殖能力较强。距离水稻根际越近标记菌株含量越高,表明菌株定殖竞争力越强。在灭菌土与未灭菌土条件下,3株菌株均具有促进水稻根系生长的能力。     

水环境中微塑料表面细菌群落特征研究进展

微塑料因其比表面积大、难降解等特点,在水环境中长期存在,可作为水环境中微生物的独特栖息地。以细菌群落为主的微生物可定殖在微塑料表面,对生态系统和人类健康产生潜在风险。本文综述了国内外海水、淡水环境中微塑料表面细菌群落特征的研究进展,阐述了微塑料表面细菌群落的研究方法和结构多样性,分析了暴露时间、地点及塑料理化性质对微塑料表面细菌群落多样性的影响,探讨了水环境中微塑料表面细菌群落的生态效应和健康风险。后续研究应采用宏基因组学全面地探究水环境中的“微塑料圈”,并关注远洋、入海口和内陆地表水微塑料表面微生物群落,从全球尺度上探索水环境中微塑料表面微生物群落的定殖规律及其生态效应。此外,鉴于微塑料表面存在降解菌,需进一步明确定殖在微塑料表面的微生物参与微塑料降解的效率及其机制,可为了解微塑料在水环境中的归宿问题提供科学依据。     

转Bt基因工程菌BioP8在环境中的消长动态及生物学效应

2001~2004年,在河北省保定市对转Bt基因荧光假单胞菌工程菌BioP8进行了环境释放,并跟踪调查该工程菌在田间的定殖、扩散、田间防效以及对田间节肢动物群落的影响.结果表明,BioP8在甘蓝叶、根及土壤中均能定殖、存活,在植物根部存活能力较强.在施药后d3,BioP8菌密度均达最高值,之后趋于衰减;BioP8对甘蓝田中天敌有较明显的保护作用,对田间节肢动物群落物种丰富度有一定的影响,BioP8防治区的节肢动物个体总量介于化防区和空白对照区的个体总量.图2表1参7     

酸雨胁迫下接种土壤微生物对栾树幼苗生长的影响

为探讨菌根真菌对宿主植物在酸雨逆境中的调节作用,以华北地区森林群落常见树种栾树(Koelreuteria paniculata)幼苗为研究对象,采用双因素完全随机试验设计开展盆栽试验,设置了3个酸雨梯度(pH分别为3.5、4.5、5.6)及2种土壤微生物接种方式(接种、不接种),对各处理下幼苗生长情况、叶片氮磷含量、根内泡囊-丛枝菌根真菌(Vescile-Arbuscular Mycorrhizal fungi)定殖情况进行测定及分析。结果表明:(1)栾树幼苗根系泡囊-丛枝菌根真菌表现出趋酸性的特征,其侵染率在pH 3.5中定殖率最高(76.3%),在pH 5.6中定殖率最低(34.4%);(2)在pH 3.5和pH 4.5酸雨处理中,接种土壤微生物显著促进了栾树幼苗的生长(P0.05),但在p H 5.6处理则无显著促进作用(P0.05),接种土壤微生物显著降低了3种酸雨胁迫下栾树幼苗叶片氮及氮磷比值,栾树幼苗在强酸胁迫下有更高的菌根依赖性(pH3.5:MD=54.2%,p H4.5:MD=38.7%,pH5.6:MD=0);(3)相关性分析表明,在pH3.5和pH4.5处理中,菌根真菌侵染率与苗木生物量、株高、基径、叶片氮及叶片氮磷比等显著相关(P0.05),而在pH 5.6处理中则均无显著相关关系。栾树幼苗泡囊-丛枝菌根真菌在强酸胁迫下表现出提高定殖率的适应策略;强酸胁迫下(pH 3.5、pH 4.5),泡囊-丛枝菌根真菌对栾树幼苗生长的调节作用较弱酸胁迫(pH5.6)明显;接种土壤微生物通过提高泡囊-丛枝菌根真菌的侵染率促进强酸雨下栾树幼苗基径、株高、地上及地下生物量。研究结果在一定程度上反映了接种土壤微生物对酸胁迫下栾树幼苗的促生长作用模式及调节作用。     

绿色荧光蛋白基因标记内生枯草芽孢杆菌

用枯草芽孢杆菌168菌株rpsD基因的启动子替换质粒pGFP4412中蜡状芽孢杆菌4412启动子,从而构建了能在枯草芽孢杆菌中表达绿色荧光蛋白基因gfpmut3a的载体pS4GFP,将其导入具有内生、防病、促生作用的野生型枯草芽孢杆菌BS-2菌株中,筛选获得遗传稳定性好且具有良好发光表型的标记菌株BS-2-gfp.该标记菌株在小白菜体内的定殖研究结果表明,该菌株能够在小白菜根际及根、茎、叶内定殖和传导,接菌50d后仍能在其体内分离到标记菌株.图5参17     

玉米内生固氮菌的回接分离及限菌条件下在玉米根内的定殖

对从玉米茎内分离的18株固氮菌进行了回接分离试验,经多碳源无氮培养基、菌落形态、颜色与REP－PCR相结合的方法,筛选、鉴定出了两株具有较高乙炔还原活性和能在玉米体内定殖的菌株R1和R6。把携带gfp标记基因的质粒pKK223-GFP和nifH-gfp的质粒pMGFP2.1分别转化R1和R6,得到携带gfp,且菌落带绿色荧光的转化子R1A和R6A,以及携带nifH-gfp的转化子R1B和R6B。在限菌条件下对R1A和R6A,在玉米根内的定殖以及R1B和R6B中nifH-gfp融合基因的表达进行了研究,结果表明了R1A和R6A主要定殖在根的皮层细胞、胞间隙、中柱细胞和导管内,有时在活的细胞内也可检测到,R1B和R6B中的融合基因因受玉米根内营养以及其它与固氮酶基因表达相关因素的限制,很难在玉米根内表达,只有在添加了1‰蔗糖后,nifH-gfp才能在根内表达。     

从水稻种子表面分离的紫云英根瘤菌与不同水稻品种亲合性的研究

采用紫云英琼脂管结瘤试验，在10个供试的不同水稻品种中，仅从“汕优63”和“珍A一代”2个品种的种子表面各分离筛选到在紫云英上结瘤较早且较多的1个菌株，分别命名为SY63－4和SA1D－3。采用无菌盆栽试验分别将这2个菌株接种于4个不同水稻品种“汕优63”、“珍A一代”、“马协63”及“博湛优19”，发现菌株ZA1D－3对4种水稻均表现出显著的促生作用，SY63－4仅对“汕优63”和“珍A一代”表现出明显的促生作用。利用MPN法检测不同水稻品种根内外根瘤菌ZA1D－3和SY63－4的数量，发现ZA1D－3和SY63－4在4种水稻根部的定殖数量也不相同。SY63－4在“汕优63”根部定殖的数量log(ncfumFW^-1/g^-1)为5．20，比在其余3种水稻根部高出2个数量级；ZA1D－3在“珍A一代”根部定殖的最大数量log(ncfumFW^-1/g^-1)为4．54，比在其余3种水稻根部高出1个数量级。这说明SY63－4与“汕优63”，ZA1D－3与“珍A一代”间存在着一定的亲和性。图1表2参12     

The Value of Species and the Ethical Foundations of Assisted Colonization

Abstract: Discourse around assisted colonization focuses on the ecological risks, costs, and uncertainties associated with the practice, as well as on its technical feasibility and alternative approaches to it. Nevertheless, the ethical underpinnings of the case for assisted colonization are claims about the value of species. A complete discussion of assisted colonization needs to include assessment of these claims. For each type of value that species are thought to possess it is necessary to determine whether it is plausible that species possess the type of value and, if so, to what extent their possessing it justifies assisted colonization. I conducted such an assessment for each of the predominant types of value ascribed to species: ecological, instrumental (including option value), existence, and intrinsic value (including interest‐based, objective, and valuer‐dependent intrinsic value). The vast majority of species, including several that have been proposed as candidates for assisted colonization, have much less value than is often presumed. Moreover, with respect to some types of value, assisted colonization would not fully preserve the value of the target species even if it were to keep the target species in existence. Therefore, the case for assisted colonization is significantly weaker and more qualified than its advocates often suppose. There may be exceptional species for which assisted colonization is well justified—and for this reason, case‐by‐case assessment is necessary—but in general the burden of justification generated by the ecological risks associated with assisted colonization is not met by the value potentially preserved by assisted colonization. This suggests that assisted colonization ought to have, at most, a very minor role in the portfolio of ecosystem management practices, even as it pertains to species conservation under conditions of rapid climate change.     

The effect of patch isolation on epifaunal colonization in two different seagrass ecosystems

The macrofaunal colonization of isolated habitats is affected by many factors, ranging from distance to the nearest source population to the dispersal mechanism of the species. We investigated the initial epifaunal colonization at two sites, one situated in the Northern Gulf of Mexico and the other in the Northern Baltic Sea. At each site, artificial seagrass units were placed at 10- and 20-m distances from a continuous seagrass meadow, as well as inside the meadow over a 5-day colonization time. With the exception of amphipods in Gulf of Mexico, patch isolation had a negative effect on colonization for the other faunal species, irrespective of the sites. This inverse colonization pattern of amphipods suggests that they are not equally sensitive to patch isolation in different regions. Our results indicate that increasing habitat isolation can have serious consequences for the community composition of seagrass epifauna. Furthermore, we emphasize the need for larger-scale latitudinal comparative studies.     

Colonization and Selection of Fly-Ash Substrates by Marine Invertebrates

Fly-ash dumped on the sea bed causes a local impoverishment of the benthos. Experiments on ash in sea water have shown bacterial colonization to occur, at a slower rate than on natural silt, limited meiofaunal colonization after 18 months, selection by meroplanktonic larvae for the ash, though inhibition of development after settlement, and selection against ash by mobile benthic adults. the major inhibition to colonization is the lack of organic content in the ash.     

沙田柚根围AM真菌的生境适宜性和季节变化性

以山地长寿沙田柚成年果树为对象,研究不同生境和季节对丛枝菌根(Arbuscular mycorrhiza,AM)真菌侵染以及根围土壤中AM真菌孢子密度的影响.试验结果表明,不同生境下,菌根侵染率和AM真菌孢子密度都是以梯田最高,坡地次之,洼地最低;在坡地和洼地生境下,生草区均高于清耕区.两块试验地AM真菌的菌丝侵染率均为夏季最高(16.8%±1.9%和16.0%±1.8%),秋季次之,冬季最低;丛枝和泡囊的形成也是夏/秋季较高,春/冬季较低;而根围土壤中AM真菌孢子密度则是秋季最高[(159±19)个/100 g和(167±17)个/100 g],夏季次之,冬季最低.总之,对于长寿沙田柚成年果树,AM真菌的菌根侵染率在夏季梯田最高,根围土壤中的AM真菌孢子密度在秋季梯田最高;在坡地和洼地生境中,生草处理均可显著提高菌根侵染率和AM真菌孢子密度.图4参27     

Neighborhood and habitat effects on vital rates: expansion of the Barred Owl in the Oregon coast ranges

In this paper, we modify dynamic occupancy models developed for detection-nondetection data to allow for the dependence of local vital rates on neighborhood occupancy, where neighborhood is defined very flexibly. Such dependence of occupancy dynamics on the status of a relevant neighborhood is pervasive, yet frequently ignored. Our framework permits joint inference about the importance of neighborhood effects and habitat covariates in determining colonization and extinction rates. Our specific motivation is the recent expansion of the Barred Owl (Strix varia) in western Oregon, USA, over the period 1990-2010. Because the focal period was one of dramatic range expansion and local population increase, the use of models that incorporate regional occupancy (sources of colonists) as determinants of dynamic rate parameters is especially appropriate. We began our analysis of 21 years of Barred Owl presence/nondetection data in the Tyee Density Study Area (TDSA) by testing a suite of six models that varied only in the covariates included in the modeling of detection probability. We then tested whether models that used regional occupancy as a covariate for colonization and extinction outperformed models with constant or year-specific colonization or extinction rates. Finally we tested whether habitat covariates improved the AIC of our models, focusing on which habitat covariates performed best, and whether the signs of habitat effects are consistent with a priori hypotheses. We conclude that all covariates used to model detection probability lead to improved AIC, that regional occupancy influences colonization and extinction rates, and that habitat plays an important role in determining extinction and colonization rates. As occupancy increases from low levels toward equilibrium, colonization increases and extinction decreases, presumably because there are more and more dispersing juveniles. While both rates are affected, colonization increases more than extinction decreases. Colonization is higher and extinction is lower in survey polygons with more riparian forest. The effects of riparian forest on extinction rates are greater than on colonization rates. Model results have implications for management of the invading Barred Owl, both through habitat alteration and removal.     

Colonization and Selection of Fly-Ash Substrates by Marine Invertebrates

Abstract

Fly-ash dumped on the sea bed causes a local impoverishment of the benthos. Experiments on ash in sea water have shown bacterial colonization to occur, at a slower rate than on natural silt, limited meiofaunal colonization after 18 months, selection by meroplanktonic larvae for the ash, though inhibition of development after settlement, and selection against ash by mobile benthic adults. the major inhibition to colonization is the lack of organic content in the ash.     

Relation between extinction and assisted colonization of plants in the arctic‐alpine and boreal regions

Assisted colonization of vascular plants is considered by many ecologists an important tool to preserve biodiversity threatened by climate change. I argue that assisted colonization may have negative consequences in arctic‐alpine and boreal regions. The observed slow movement of plants toward the north has been an argument for assisted colonization. However, these range shifts may be slow because for many plants microclimatic warming (ignored by advocates of assisted colonization) has been smaller than macroclimatic warming. Arctic‐alpine and boreal plants may have limited possibilities to disperse farther north or to higher elevations. I suggest that arctic‐alpine species are more likely to be driven to extinction because of competitive exclusion by southern species than by increasing temperatures. If so, the future existence of arctic‐alpine and boreal flora may depend on delaying or preventing the migration of plants toward the north to allow northern species to evolve to survive in a warmer climate. In the arctic‐alpine region, preventing the dispersal of trees and shrubs may be the most important method to mitigate the negative effects of climate change. The purported conservation benefits of assisted colonization should not be used to promote the migration of invasive species by forestry.     

Securing the Demographic and Genetic Future of Tuatara through Assisted Colonization

Abstract: Climate change poses a particular threat to species with fragmented distributions and little or no capacity to migrate. Assisted colonization, moving species into regions where they have not previously occurred, aims to establish populations where they are expected to survive as climatic envelopes shift. However, adaptation to the source environment may affect whether species successfully establish in new regions. Assisted colonization has spurred debate among conservation biologists and ecologists over whether the potential benefits to the threatened species outweigh the potential disruption to recipient communities. In our opinion, the debate has been distracted by controversial examples, rather than cases where assisted colonization may be a viable strategy. We present a strategic plan for the assisted migration of tuatara (Sphenodon punctatus), an endemic New Zealand reptile. The plan includes use of extant populations as reference points for comparisons with assisted‐colonization populations with respect to demography, phenotypic plasticity, and phenology; optimization of genetic variation; research to fill knowledge gaps; consideration of host and recipient communities; and inclusion of stakeholders in the planning stage. When strategically planned and monitored, assisted colonization could meet conservation and research goals and ultimately result in the establishment of long‐term sustainable populations capable of persisting during rapid changes in climate.     

An island biogeography approach for understanding changes in compositional similarity at present scenario of biotic homogenization

Local extinction of native species and colonization of non-native species are commonly invoked as responsible for changes in species similarity among biotas of different regions. In this study we used a model of species similarity between islands to assess the emergent, and unexplored, effects of changes in colonization by native species, extinction of non-native species, and propagule pressure on species similarity among insular communities. The model predicts that extinction probability of endemic species has a positive but asymptotic effect on species similarity, which is exacerbated by increasing colonization and reducing extinction of non-native species. Species similarity tends to increase with increasing colonization probability by non-native species, however this effect may be reduced, or even reverted, when the islands are exposed to an elevated number of non-native species that are prone to extinction, high levels of endemic species loss, and an initially large number of native species shared between islands. Species similarity was positively affected by the propagule pressure rate of non-native species only when their colonization and extinction probabilities were large and small enough, respectively. A negative effect of propagule pressure rate can be caused by an increase in the pool size of non-native species, which involves the introduction of different species into different islands, promoting biotic differentiation between islands. Our results indicate that the interactions between colonization, extinction and species pool lead to nonlinear responses and unexpected scenarios of biotic change. In order to validate model predictions, future research programs should focus on understanding the dynamics on such complex meta-communities where coexist native, non-native and endemic species.     

Colonization dynamics in trophic-functional structure of periphytic protist communities in coastal waters

The colonization dynamics in trophic-functional patterns of periphytic protist communities was studied in coastal waters of the Yellow Sea, northern China, from May to June, 2010. The periphytic protists represented different trophic-functional structures during colonization process. Only certain trophic-functional groups (e.g., photoautotrophs, algivores and non-selectives) occurred within the protist communities with low species number and abundance at the initial stage (1–3 days), while more trophic-functional groups (e.g., photoautotrophs, algivores, non-selectives and raptors) contributed to the communities with increased and peaked species number and abundance at the transitional (7–10 days) and equilibrium (14–28 days) stages, respectively. All heterotrophic groups were significantly fitted the MacArthur–Wilson model in colonization curves and represented higher species number and colonization rates at a depth of 1 m than at 3 m. These results may provide necessary understandings for ecological researches and monitoring programs using periphytic protists with different colonization ages in marine ecosystems.