The phycobiota-derived proteins Pµ84 and Pµ19 suppress bacterial biofilm formation in gram-negative pathogens

Microalgae are typically found in freshwater and marine systems and they harbor a mostly a beneficial growth promoting microbiota. We have recently isolated several small proteins from the microbiomes of microalga (Scenedesmus quadricauda, Microasterias crux-melintensis, Chlorella saccherophilia) and have tested them for their role in either inhibition of biofilm formation and/or biofilm degradation. Thereby we have identified two candidate proteins that showed promising activities on biofilm inhibition and degradation. These proteins were designated Pµ84 and Pµ19 and strongly affected biofilm formation in several human- and plant-pathogenic bacteria. Recombinant and purified Pµ84 and Pµ19 were applied in biofilm assays in microtiter plates and reduced biofilms formed by Stenotrophomonas maltophilia, Pseudomonas aeruginosa and Klebsiella pneumonia. If expressed in the different hosts, biofilms were reduced by a factor of 40% and if applied as exogenous proteins, biofilms were reduced up to 20%. Pµ84 application also resulted in a delayed biofilm formation and biofilm formation was affected by a factor of 17%. The microprotein Pµ19 consist of 57 aa and Pµ84 consists of 49 aa. Ongoing work elucidates the mechanism of Pµ84 and Pµ19 on the reduction of biofilm in order to achieve the optimal activity.