Purificação, caracterização e avaliação de peptídeo antimicrobiano produzido pela cianobactéria amazônica Lyngbya sp. CACIAM 07

Abstract

Cyanobacteria are photosynthesizing microorganisms that, together with micro and macroalgae, are responsible for most of the oxygen released into the atmosphere. One defense mechanism of cyanobacteria is the production of compounds that exhibit antimicrobial, allelopathic, and antiparasitic activities, protecting the organism against attacks from other species of cyanobacteria, predators, and microorganisms in general. The genus Lyngbya is one of the most studied due to its promising production of molecules of biotechnological interest, such as peptides, proteins, and secondary metabolites, which can be used in various areas to address problems that afflict society and the environment, such as crop pests, food contamination, and the lack of new commercial antimicrobials. The aim of this study was to obtain, evaluate, and characterize the peptide with antimicrobial activity produced by the Amazonian cyanobacterium Lyngbya sp. CACIAM 07. The extract was obtained from the dried biomass of the cyanobacterium, and its antimicrobial activity was evaluated by well diffusion against gram-positive (Bacillus subtilis ATCC 6633, Listeria monocytogenes ATCC 6477, and Corynebacterium fimi NCTC 5) and gram-negative (Salmonella typhimurium ATCC 14021) bacteria. The aqueous extract showed the greatest activity against the target bacteria, inhibiting the growth of three of the four bacteria used in this study: Bacillus subtilis ATCC 6633, Salmonella typhimurium ATCC 14021, and Listeria monocytogenes ATCC 6477. It also inhibited the growth of the cyanobacterium Cyanobium sp. CACIAM 14. The crude aqueous extract was purified using molecular exclusion chromatography and then reversed-phase liquid chromatography. The collected fractions were tested for their antimicrobial and allelopathic activity, with fraction C7B1 showing the best activity against Bacillus subtilis ATCC 6633, Salmonella typhimurium ATCC 14021 and demonstrating allelopathic activity against Synechococcus sp. CACIAM 66. According to the chromatograms, it was possible to determine the size of the molecule, which was 12 kDa, consistent with an antimicrobial peptide. Thus, in this work, it was possible to isolate, analyze, and partially characterize the activity of the possible AMP obtained from Lyngbya sp. CACIAM 07, a cyanobacterium isolated from the Amazon region. We would point out that no molecule with antimicrobial or allelopathic activity from this strain has been described in the literature to date.