Extracellular enzyme activities of aquatic bacteria in polluted environment: 2. Amylolytic activity

Water samples were taken from Lake Drukshiai tributaries (Ricanka); Gulbinele Stream affected by urban rain sewerage from Visaginas; Gulbinele Stream into which municipal sewage from Visaginas (MS) and industrial rain sewerage from the Ignalina NPP and their mouth, and Lake Dringis. Lake Dringis, in Aukstaitija National Park, was selected as an ecosystem pattern of a weak anthropogenic influence, while Lake Drukshiai was chosen as a regularly polluted water body. Lake Drukshiai, the cooling basin of the Ignalina NPP (IRS-1.2), is being polluted with industrial and municipal sewage through its tributaries. The amylolytic activity (AA) of heterotrophic aquatic bacteria was tested. The highest total mean AA of aquatic bacteria was calculated in Lake Dringis. Here, the results were significantly higher than in Lake Drukshiai tributaries and their mouths, excepting the mouths of the Ricanka and MS. The lowest mean of AA in Lake Drukshiai was characteristic of the IRS-1.2 tributary. A comparison of the mean AA of active isolates showed that certain bacterial strains from the sites of varying degrees of pollution could be noted for a relatively high level of enzymatic activity. Thus, anthropogenic pollution exerts a negative effect on the total mean AA, although certain strains of bacteria are able to adapt to the stressful environment and remain active. (author)