Because of the low affinity for organic matter, copiotrophic bacteria favors an abundance of readily available organic matter in the environment, while oligotrophic bacteria with high affinity for organic matter are adapted to the conditions of a small amount of readily available organic matter. The aim of the study was to determine whether there is a limitation of copiotrophic and oligotrophic bacteria with regard to organic matter during different seasons. The survey was conducted during the year 2008/2009 in the Kopački Rit, and water samples for research were collected from the bottom water layer of Sakadaš Lake. One part of the water samples was enriched with peptone in different concentrations and durations of preincubation to determine whether are bacteria limited with organic matter by comparing the number of bacterial colonies in the sample with the addition and without the addition of peptone. Addition of peptone caused a significant increase in the number of bacterial colonies in all four seasons, which means that bacteria are limited with regard to organic matter throughout the year. During spring and summer the concentration of labile organic matter increased enough to support the development of oligotrophic bacteria, while copiotrophic bacteria only slightly increased in the summer. The strongest stimulation of copiotrophic bacteria was in the spring and summer, while at the same time oligotrophic bacteria were least stimulated with peptone. Significant stimulation of copiotrophic and oligotrophic bacteria was achieved already at a concentration of 100 mg / L and preincubation of 18h, while the maximum stimulation was achieved with peptone concentration of 1000 mg / L at preincubation of 72 hours.