赤潮过程中“藻-菌”关系研究进展

A review of the relationship between algae and bacteria in harmful algal blooms

微生物对促进海洋物质循环,维持水生环境的生态平衡具有重要作用。在赤潮事件中,基于微生物(尤其是细菌)的多样性和重要性,它们与藻类之间的相互关系成为了研究的热点。过去20年里,人们从不同角度对"藻-菌"间的关系进行了探索,包括物理学过程、生物学过程、环境过程以及化学过程。就化学过程而言,它作为一种较早出现的技术,在以往的研究中带给人们许多认识藻菌关系的方法。随着学科的渗透,化学法有了拓展与延伸,为人们认识藻菌关系带来了新的契机。从化学生态学领域来梳理"藻-菌"关系中涉及的现象和行为,包括菌对藻的有益面、菌对藻的有害面、以及藻类应答细菌行为的化学途径;并从信号语言(群体感应、化感作用)的角度来阐释两者之间的互生或克生关系。通过文献综述的方式来解读藻菌关系的互作过程和机理,为认识赤潮的发生和防控方法提供借鉴。

Marine microbes play important roles in the marine ecological system. They influence the climate, mediate primary production, participate in biogeoehemical cycles, and maintain ecological balance. The microbes that make up harmful algal blooms （including bacteria, archaea, microbial eukaryotes and their associated viruses） are being studied closely by scientists. Because of high diversity and complexity, the interaction between algae and bacteria has become the concern of many researchers. Over the past 20 years, people have explored the relationships between algae and bacteria from different perspectives, including the physical, biological, environmental and chemical processes involved. Chemical ecology offers many methods to study and understand the relationships between algae and bacteria. Researchers have observed many different interactions between alage and bacterial, including competition, mutuatism and parasitism. These microbes, which exist as free-living forms as well as securely attached to algal cells, have now been demonstrated to modulate （ either positively or negatively） algal growth rates and transitions between life history stages, influence toxin production, and even induce the rapid lysis of algal cells. However, given the complex array of interactions that have evolved between them, some ecological functions and related mechanisms have not yet been fully elucidated. Biotic interactions play an important role in community regulation. Though some of the chemical response mechanisms can be clearly attributed to either the alga or to itsepibiont, in many cases the producers, as well as the mechanisms triggering the biological behaviour, remain ambiguous. Chemical ecology brings new opportunities to explore the interactions between algae and bacteria. This paper reviews the relationships between algae and bacteria from a chemical ecology viewpoint, including both benefical and negative effects on the algae. Positive algae-bacteria interactions include phytohormone production, morphogenesis of microalgae triggered by bacterial products, specific antibiotic activities affecting epibionts and the elicitation of oxidative burst mechanisms. Deleterious algae-bacteria interactions include induction of algal diseases, growth inhibition, an influence on algal metabolism and production of antibiotic compounds. The mechanisms concerning the algal response to bacteria from a chemical signal perspective （ such as, quorum sensing and allelopathy） are also addressed. Signal molecules are considered to play a potentially important role in structuring phytoplankton communities and affect the population dynamics of harmful algae species. Future work should focus on three research aspects. 1 ） how microbes and their secondary metabolites regulate their ecological division and social characterization with chemical signals in the phycosphere environment. 2） analysis of the secondary metabolites of algae and bacteria in situ in the algal-bacterial symbiotic system possibly using a new method called desorption electrospray ionization mass spectrometry （ DESI-MS ）. 3 ） Coupled application of chemical and molecular biological methods to study the interaction of alage and bacterial. Some new tools should be widely applicable, such as bioinformatics, metagenomic technology and development of online monitoring instruments. The aim of this paper is to interpret the complex ecological interaction and the related mechanisms between planktonic algae and bacteria in a new way. This review can provide a reference for readers to understand red tide processes and help develop novel ways to prevent or control harmful algal blooms.