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Physiological characteristics and ecological role of small and large size bacteria in a polluted river (Seine River, France)

par Garnier, Josette;Billen, Gilles ;Servais, Pierre
Référence Ergebnisse der Limnologie, 37, 1, page (83-94)
Publication Publié, 1992

Article révisé par les pairs

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Résumé :

In the Seine River, the effluent of a water treatment plant introduces large bacteria ( greater than or equal to 1 mu m) leading to a sharp increase in both bacterial biomass and activity; a rapid decrease is then observed downstream. Incorporation of four tracers (amino acids mixture, glucose, thymidine and leucine) has shown that specific activity of large bacteria ( greater than or equal to 1 mu m) was, in average, 3 times higher that of small bacteria (0.2-1 mu m). Potential proteolytic activity as well as half saturation constant (Ks) were, however, similar for large and small bacteria. A model of bacterial dynamics has been established providing a good simulation of observed bacterial biomass and production as well as of dissolved organic matter. The model has been used to describe the competition between the two populations. With a higher growth rate and a similar affinity for substrates, the large bacteria appeared to limit the development of smaller ones, but their rapid disappearance in the river resulted in a slower degradation of organic matter.