The occurrence of lipolytic bacteria and the activity of extracellular lipases in a riverine ecosystem

This study determined the numbers and distribution of heterotophic and lipolytic bacteria and the activity of lipases in the water of the Słupia River, in the section of the river that flows through the city of Słupsk. From spring to fall the mean number of heterotrophic bacteria remained at a relatively constant level (158.3 × 10³ cells cm^-3-169.4 × 10³ cells cm^-3), whereas in winter a sudden drop to only 18.3 × 10³ cells cm^-3 was found. The numbers of heterotrophic bacteria in the whole studied section of the river were similar. The mean number of lipolytic bacteria reached a maximum in spring (12.9 × 10³ cells cm^-3), was high in summer (10.5 × 10³ cells cm^-3), and reached a minimum (1.3 × 10³ cells cm^-3) in winter. Lipolytic bacteria accounted for only 5 to 8% of the total number of heterotrophic bacteria. No marked differences in the numbers of lipolytic bacteria were determined within the section of the river studied. The highest levels of lipase activity were determined in spring (18.9 nM MUF dm^-3 h^-1) and fall (19.9 nM MUF dm^-3 h^-1), while the lowest (11.0 nM MUF dm^-3 h^-1) were noted in winter. There were no differences in the level of activity of lipolytic enzymes among the sites studied.