Abstract

Microalgae and bacteria are the primary colonists of marine surfaces, forming the initial biofilm layer needed for posterior macro organism fixation. This phenomenon, termed biofouling, greatly deteriorates ships, piers, and aquaculture systems. Biofouling is currently treated with toxic and poorly degradable chemicals, resulting in significant environmental concerns. Consequently, increasing research efforts are focused on antifouling microorganisms as a measure to take care of the environment and avoid the use of harmful chemicals for marine flora and fauna. The objective of the present study was to evaluate the ability of the marine bacterium Bacillus pumilus (C32-MESO) in inhibiting to the substrate fixation of the benthic microalgae Nitzschia ovalis arnott and Navicula incerta known for forming biofilms on substrates. A total of 26 bacterial morphotypes were isolated that grow associated with microalgae cultures N. ovalis arnott and N. incerta. The results showed that the bacteria B. pumilus (C32-MESO) inhibited 96.4% of these isolated morphotypes and significantly decreased microalgae density when inoculated with the cultures. Substrate adherence assessments revealed that B. pumilus (C32-MESO) decreased the adherence of both microalgae to shell and PVC substrates. In conclusion, this study lays the foundation for future research into characterizing the active metabolites derived from B. pumilus (C32-MESO) and evaluate the biotechnological applications of this bacterium in naturally inhibiting the early stages of biofilms such as fixing to substrates of microalgae.