Epiphytic bacteria, Ulva lactuca, culture-based bioprospecting, genome of a producer bacteria of laccases

Marine enzymes have characteristics of interest in various biotechnological processes, because, many are active under exceptional physicochemical conditions. In this sense, the epiphytic bacterial communities of macroalgae of the species U. lactuca are a promising source of novel enzymes produced by the bacteria to metabolize different substrates provided by the macroalgal surface. In this study, functional screening of two enzymes (ulvane-lyases and lacases) was performed on 90 epiphytic bacteria isolated from the surface of U. lactuca, collected in La punta de la Loma, Santa Marta (Colombian Caribbean). A total of 24 isolates were screened positive to laccase activity tested in three substrates (guaiacol, 2,6-DMP, and tannic acid), belonging to the genera Bacillus, Brevibacterium, Lysinibacillus, Pseudomonas, Shewanella, Vibrio, Alcaligenes, and Achromobacter. The assess for lyases did not show conclusive results regarding the production of this type of enzyme in the isolates of interest. In order to corroborate the presence of laccase-coding genes in the isolates obtained, the Achromobacter denitrificans EPI-24 strain was selected due to its bioremediation potential. The in silico confirmation of the presence of laccase was verified by the assembly and annotation of its genome. The results identified two gene products (Multicopper Oxidase and Multicopper Polyphenol Oxidase), which could be responsible for the laccase activity detected in the plate, demonstrating the potential of epiphytic bacteria of U. lactuca in the production of enzymes, which could present unique functional properties under more versatile and efficient conditions, compared to conventional lacases produced by terrestrial fungi.