Caracterização polifásica de microrganismos fotossintetizantes da Chapada das Mesas

Abstract

The great diversity of cyanobacteria does not only include the morphological variability and habitat preferences, but also the bioactive metabolites produced by these microorganisms. The National Park of Chapada das Mesas is home to a diversity of photosynthetic microorganisms still underutilized and with biotechnological potential and direct consequences for tourism in the region. The objective of this work was to characterize, through a polyphase approach, photosynthetic microorganisms isolated from Chapada das Mesas - Maranhão. Isolation was obtained by collecting sediment and water samples in water bodies inside and outside the park area. The morphological characterization was performed through optical microscope observations and ultrastructural analysis using atomic force microscopy. Isolates were also identified using phylogenetic and functional gene markers (16S rRNA and the saxotoxin and microcystin genes). In addition, analyzes of mass spectrometry and bioactivity tests against bacteria, fungi and ticks were carried out. Morphological characterization identified samples GBBB01 and GBBB02 as belonging to the genus Nostoc/Desmonostoc and GBBB05 as Pantanalinema, a description which was confirmed by the sequencing which had comparative results above 94% similarity for GBBB02 and 05. In the analyzes of ultrastructure in AFM strain GBBB01 (Nostoc sp.) showed cells arranged alone, not forming trichomes. For GBBB05 the cells were arranged in the joined filaments along the trichomes, being possible to observe differentiated cells and cylindrical apical cell corroborating with the description by morphology. The presence of cyanotoxin metabolic pathway genes could not be detected via polymerase chain reaction. It was not possible to identify characteristic spectra of bioactive compounds known as cyanotoxins or cyanobacins in mass spectrometry of extracts from GBBB01, 02 and 05 samples. The bioactivity tests also showed no positive results, within the concentrations used, against any of the strains tested. The results indicate that the cyanobacteria present in the water bodies of the Chapada das Mesas are not toxic, and there is no imminent risk for local residents and tourists. However additional analyzes are required to completely rule out the production of bioactive secondary metabolites in the isolates obtained.