engleski

Interactions within a methanotrophic-heterotrophic groundwater community

The main objective of this work was to study relationships and interactions within the methanotrophic-heterotrophic community enriched from aquifer solids and characterized to be a stable association, consisting of one obligate (type II) methanotroph and four to five heterotrophs of different nutritional and metabolic characteristics (1). All experiments were performed in a closed system (sealed shake flasks) in nitrate mineral salts (NMS) medium with the addition of methane as the only carbon and energy source. Growth kinetic experiments were performed under different methane and oxygen concentrations in the headspace (CH_4, 4.5-19.4 percent; O_2, 15.5-19 percent) at the temperatures of 20and 30^oC. To evaluate possible relationships between community populations, a series of experiments were carried out in which nutritional requirements of individual populations and the mutual growth inhibition/stimulation effects were studied by cross-growing the methanotroph in the presence of individual heterotrophs and their lysates. The results of growth kinetic experiments confirmed previous observation that the six-membered groundwater community possessed stable growth characteristics under various conditions, with almost regular appearance of all community populations. This illustrated the capacity of the community to self-regulate in response to changing growth conditions and suggested that groundwater community was structured on specific relationships between the obligate methanotroph and the present heterotrophs.

relationships; interactions; methanotrophic-heterotrophic community

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