Numerical analysis on planktonic bacterial communities of red belt surrounded "inner-lakes" of Lake Ferto

The so-called "inner-lakes" (Herlanki, Kis-Herlanki, Hidegsegi-to) of the shallow, turbid and sodic steppe-lake, Lake Ferto (Hungary) are isolated water bodies. They separated from the open lake water by wide red belts and concomitantly have a very special water chemistry. The typically brown waters are characterised by high organic content (humic acids too) and high salinity (Na+=450 mg/l, Mg2+=140 mg/l, SO2- 4=440 mg/l). Open water samples were taken from the three "inner-lakes", and the composition of bacterial communities was investigated by detailed biochemical-physiological characterisation of selected strains using numerical methods. The dominant microorganisms in the open water of all the three "inner-lakes" constitute of Micrococcus variants and of Flavobacterium species. The former seems to be highly adapted to these unique environments. Unfortunately the typically oligocarbophilic flavobacteria showed very little activity in the standard biochemical and physiological tests. Pleomorphic Gram positive rods were also isolated in lower numbers, which turned to be members of the genus Arthrobacter, a typical soil organism. Their presence in probably associated with the high organic substrate, especially hardy degradable biopolymer concentration of the inner lake water. Other very much pleomorphic but Gram negative rods could have been identified as members of the Cytophaga-Flavobacterium group belonging into genera Flectobacillus, Flexibacter and Cytophaga. These organisms are also active in the degradation of most diverse biopolymers. A local variety of Staphylococcus xylosus seems to play much less role in these special habitat as the above mentioned organisms, but the presence of Staphylococcus in such habitats at least noticeable. Similarly the loss of importance of Pseudomonas species can possibly be elucidated by the special water chemistry of "inner-lakes", since these organisms are in dominant populatory position in the open water of Lake Ferto