Institute for Inorganic and Analytical Chemistry, Bioorganic Analytics, Friedrich Schiller University Jena, Jena, Germany.
Max Planck Institute for Chemical Ecology, Jena, Germany.
Microbiologyopen. 2019 Aug;8(8):e00818. doi: 10.1002/mbo3.818. Epub 2019 Feb 27.
Algicidal bacteria are important players regulating the dynamic changes of plankton assemblages. Most studies on these bacteria have focused on the effect on single algal species in simple incubation experiments. Considering the complexity of species assemblages in the natural plankton, such incubations represent an oversimplification and do not allow making further reaching conclusions on ecological interactions. Here, we describe a series of co-incubation experiments with different level of complexity to elucidate the effect of the algicidal bacterium Kordia algicida on mixed cultures of a resistant and a susceptible diatom. The growth of the resistant diatom Chaetoceros didymus is nearly unaffected by K. algicida in monoculture, while cells of the susceptible diatom Skeletonema costatum are lysed within few hours. Growth of C. didymus is inhibited if mixed cultures of the two diatoms are infected with the bacterium. Incubations with filtrates of the infected cultures show that the effects are chemically mediated. In non-contact co-culturing we show that low concentrations of the lysed algae support the growth of C. didymus, while higher concentrations trigger population decline. Complex cascading effects of algicidal bacteria have thus to be taken into account if their ecological role is concerned.
杀藻细菌在调节浮游生物群落的动态变化中起着重要作用。大多数关于这些细菌的研究都集中在简单孵育实验中对单一藻类物种的影响上。考虑到自然浮游生物中物种组合的复杂性，这种孵育方法过于简单化，无法对生态相互作用做出进一步的结论。在这里，我们描述了一系列具有不同复杂程度的共孵育实验，以阐明杀藻细菌 Kordia algicida 对耐受力和易感性硅藻混合培养物的影响。在纯培养中，耐受力硅藻 Chaetoceros didymus 的生长几乎不受 K. algicida 的影响，而易感性硅藻 Skeletonema costatum 的细胞在数小时内被裂解。如果两种硅藻的混合培养物感染了这种细菌，C. didymus 的生长就会受到抑制。用感染培养物的滤液进行孵育表明，这些影响是化学介导的。在非接触共培养中，我们发现低浓度的裂解藻类支持 C. didymus 的生长，而较高浓度则引发种群下降。因此，如果涉及杀藻细菌的生态作用，就必须考虑到它们复杂的级联效应。
