Biological interactions between microorganisms in the sea

• Published in: Marine chemistry 1977-01, Vol.5 (4), p.553-555
• Main Authors: Aubert, M., Gauthier, M.J.
• Format: Article
• Language: English
• ISSN: 0304-4203; 1872-7581
• DOI: 10.1016/0304-4203(77)90041-X

Marine ecosystems, like terrestrial biological communities, are generally considered to depend, regarding their structure and functioning, upon the trophic and sexual relationships between organisms, either “horizontally”, between individuals at the same level, or “vertically”, all the way down the various levels of the food chains. Nevertheless, the functioning of biosystems is mostly governed by their structure, i.e., the qualitative and quantitative distribution of individuals within biocenoses, as well as the relationships with one another and with the environment. Therefore, it is vital to get to know how these connections work in order to outline the main causes of microbiological equilibrium in the sea. Actually, the major problem remains that of communication between individuals in biocenoses. This is a general problem as far as life is concerned, but it proves especially acute when it comes to microbial life because of its importance in the oceanic cycles. Data available in the literature, together with the results of our own studies in this field, led us to the assumption that some of the dissolved organic substances present in seawater might well be responsible for the control of the relationships between species. These substances would be active at various degrees of concentration, after they have been released into the medium by certain species. This theory, already adumbrated by Lucas (1938, 1947, 1955), Nigrelli (1958) and Fontaine (1970) concerning direct relationships between marine species or groups of organisms, was resumed and generalized by M. Aubert (1971) who called these substances “telemediators”. Such chemical communication plays a major role in a variety of fields including sexual behaviour, nutrition and predation, as well as defense mechanisms, mobility and migration. Remote connection of two organisms through a chemical mediation involves a sequence of actions and reactions which raises a number of problems of biochemical microecology. The organism that produces the telemediator must synthesize it — either spontaneously or in an induced way — and release it into the medium, during its active growth or after cell lysis. Next, the mediator is conveyed to the remote receiving organism, which it should reach without being degraded or chemically modified (or after such a modification. Its concentration must remain equal to or higher than its activity threshold. The receptor detects it, with or without absorption, and reacts by modi