Predator-induced changes of bacterial size-structure and productivity studied on an experimental microbial community
Predator-induced changes of bacterial size-structure and productivity studied on an experimental microbial community
复制标题
在实验微生物群落中研究捕食者引起的细菌大小结构和生产力的变化
DOI：
10.3354/ame018235
复制
发表时间：
1999
影响因子：
1.4
通讯作者：
R. Psenner
中科院分区：
文献类型：
--
作者：
T. Posch;K. Šimek;J. Vrba;J. Pernthaler;J. Nedoma;B. Sattler;B. Sonntag;R. Psenner
在一个二级流动系统中，利用一个小型的、功能可重复的微型生物食物网，研究了3种原生动物在一个安静的细菌群落中的摄食冲击。第一阶段，藻Rhodiasp生长在无机介质中，其伴随的细菌群落（BC）生长在藻分泌物上，第二阶段，藻分泌物上的细菌群落（BC）生长在无机介质中。将藻类和绿藻的混合物转移到4个第二阶段容器中（1）对照和3个接种有（2）异养纳米鞭毛虫Bodo saltans（3）Scuticocate，Cyclldlum glaucoma和（4）mxotroph鞭毛虫的容器，本文应用图象分析技术，在15 d的实验期内，跟踪观察了嗜铬单胞菌的菌体数和菌体对原虫总生物量的变化。用[ 3 ~ ] thymidine和[3 ~] cleuc ~ne测定了放牧和未放牧的BC的生产力。由于总放牧率和大小选择摄食量的结果，我们观察到最初相同的BC对3种原生动物放牧的3种不同反应（1）B菌低浓度接触可使细菌细胞数从14 × 10 ~（-1）h细胞/m ~ 3缓慢下降到5 × 10 ~（-1）H细胞/m ~ 3，但平均细胞体积（MCV）和细菌产物无明显变化。细菌丰度达3.3 × 106个细胞ml ~（-1），MCV加倍至0.207 μ m ~ 3，DNA和蛋白质合成率高。由于也能吃小猎物（<1.5 μ m），MCV的增加似乎提供了高的抗放牧性或至少降低了抗放牧性。(3)结果表明，Ochromonas sp.的摄食率最高，2d内细菌数减少了20倍。只有少量的食草保护细菌（<0.9 pm）存活，此后增加到几乎初始的细菌密度。尽管细菌MCV下降到0.038 pm 3，每个细胞的[3 H]胸苷摄取率大大提高，并且高度可变。我们的研究结果反映了BC对不同捕食制度的潜在反应和表型性状的优势，以便与各种食草动物共存。这应该在影响自下而上效应和单个细菌物种改变形态，生长策略和活动模式的不同潜力的背景下看到。
The grazlng unpact of 3 different protozoan specles on a muted bacter~al community was studled by means of a s ~ m p h i ~ e d and funct~onally reproducible expenmental m~crobial food web In a 2stage flow-through system In the first stage the algae Rhodomonas sp was grown on an inorganic medlurn wlth its accompanying bacterial community (BC) growing on algal exudates T h ~ s m t u r e of algae and bacterla was transferled Into 4 second stage vessels (1) a control and 3 vessels inoculated wlth (2 ) a heterotrophic nanoflagellate Bodo saltans (3) a scuticoc~l~ate, Cyclldlum glaucoma, and (4) a mxotroph~c flagellate, Ochromonas sp Us~ng Image analysis techn~ques we followed the changes In bactenal s u e &stnbut~ons and bactenal to protozoan total biovolume rat~os over an expermental period of 15 d In add~tion productivity of the grazed and ungrazed BC was measured using [ 3 ~ ] t h y m ~ dine and ['"C]leuc~ne As a consequence of total grazing rates and size-select~ve feedlng we observed 3 d~fferent responses of the initially ident~cal BC to grazing of the 3 protists (1) LOW grazlng by B saltans caused a slow decrease of bactenal cell numbers from 14 to 5 9 X 10h cells m ' , but no s~gnlflcant shlft of the mean cell volume (MCV, average 0 107 pm3) and bacter~al product~on (2) H~gher grazing rates of C glaucoma resulted In the dechne o! bactenal abundance to 3 3 X 106 cells ml-' In parallel with a doubllng of the MCV to 0 207 pm3 and high DNA and protein synthes~s rates Due to the cha te S ab~lity to graze also on small prey ( < l 5 pm) an increase in MCV seemed to provide h l g h e ~ grazing resistance or at least decreased vulnerab~lity. (3) Ochromonas sp. showed the hlghest grazlng rates and reduced bacterial numbers by 20 times wlthin 2 d. Only the smal les tobv ious ly more grazing-protectedbacteria (<0.9 pm) survived, which increased thereafter to almost initial bacterial densities Although the bacterial MCV dropped to 0.038 pm3, [3H]thymidine uptake rates per cell were greatly enhanced and highly variable. Our results reflect the potential of BC responses to different predation regimes and the advantages of phenotypic traits in order to coexlst with various grazers This should be seen in the context of influencing bottom-up effects and the varying potential of individual bacter~al specles to change morphology, growth strategies, and activ~ty patterns.