Resumen
Balaton is the largest shallow lake in Central Europe. It is one of the few lakes where eutrophication processes have been successfully reversed. The creation of a wetland area on the lower part of the main inflow river played a major role in the re-oligotrophication processes. After several decades of operation and multiple transformations, an attempt was made to explore the microbial community of the water reservoir and its relationship with algal groups and environmental parameters. In the main inflow river, floods had the greatest effect on the microbial community composition, while in the open water areas of the wetland system, the algae production that develops due to external nutrient load was the main driver of the bacterial community. In the high-macrophyte-covered areas, the decomposition processes of the dying algae biomass were the most decisive. Finally, in the large open water areas of Lake Balaton, the external and internal nutrient loads together determined the algal production and thus the bacterial community composition.