Baltic Sea constitutes a unique environment of brackish water conditions, with a significant influence of seasonal freshwater deposits and of agricultural and industrial pollution from the surrounding lands. This challenging ecological niche leads to bacterial adaptation to diverse stress conditions. The long-term goal of this project is to identify molecular mechanisms that govern stress responses and fitness advantages of Baltic Sea bacteria in a number of stress conditions previously reported by The Baltic Marine Environment Protection Commission (HELCOM) to affect the Baltic Sea biodiversity. To achieve this goal, bacterial species isolated from the Gulf of Gdansk, a southeastern bay of the Baltic Sea region, are analyzed at the genome, transcriptome and proteome levels.