Identification and molecular characterization of tropical cyanobacteria of the genus Nostoc, Calothrix, Tolypothrix and Scytonema (Nostocales: Nostocaceae), with possible biotechnological potential. Cyanobacteria or "Blue-Green" algae comprise a diverse cluster of prokaryotic photoautotrophs that share a high morphological and molecular abundance. Biotechnological advances on nitrogen fixation, bioremediation, pharmaceutical and nutritional value have been developed. Traditional identification based on morphology has been the most common applied technique, but it may be inaccurate because of the phenotypic plasticity that those organisms present. For this reason, molecular techniques had become robust tools for taxonomic positioning of tropical cyanobacterial isolates, associated with morphology identification. This study focuses on the morphological identification and molecular characterization of cyanobacteria isolated in different tropical environments of Costa Rica, for biotechnological prospects. Strains were grown in BG 0 -11 media, photographed under light microscope and classified at genera level. Molecular identification was carried by PCR and sequencing using DNA-dependent RNA polymerase (rpoC1) and small-subunit ribosomal RNA (16S rRNA) gen primers. Subsequently, a phylogenetic positioning analysis was performed by MAFFTv.7 alignment and maximum likelihood by raxMLGUI. Based on phenotypic characteristics, four genera of Nostocales were identified: Calothrix sp., Tolypothrix sp., Scytonema sp. and Nostoc sp. Molecular analysis shows a taxonomic grouping that is consistent with the observed morphology, with the 16S rDNA gene yielding robust and stable results. The identified genera are known for their nitrogen fixation capability: Nostoc and Calothrix have been used in maintaining fertility and soil recovering studies. Nostoc is known for its nutritional properties and biofuel production; a characteristic shared by Tolypothrix as well. The last genera; Scytonema, it is known for its pharmacological properties. With the successful identification of cyanobacteria strains isolated from tropical environments, it is possible to continue the study of genes responsible for properties of biotechnological interest and to evaluate their potential, with future perspectives of application and biodiversity conservation.Key words: Cyanobacteria, 16S rRNA, rpoC1, characterization molecular, morphological identification, biotechnological potential. RESUMEN:Las cianobacterias son procariotas fotoautótrofos, morfoló-gica y molecularmente diversas, en las cuales se han reportado avances biotecnológicos sobre fijación de nitrógeno, biorremediación y valor nutricional-farmacéutico. La identificación tradicional de cianobacterias basada en morfología puede ser imprecisa, por lo que las técnicas moleculares son una herramienta robusta para el posicionamiento taxonómico de estas cepas tropicales. Este estudio se enfoca en la identificación morfológica y caracterización molecular de cianobacterias de ambientes tropica...
Abstract:Currently, nitrogen has become the main element of water pollution, causing riverine, lacustrine and coastal eutrophication. The continuous contamination of aquifers and the absence of planned water resource utilization, boost its scarcity, and has been the only way in which our societies become aware of the urgent need to process the generated wastewater. The objective of this research was to evaluate the nitrifying capacity of different autochthonous bacterial isolates from soils from nearby sources of domestic wastewater drainage. For this, bacteria were isolated from Pirro River, contaminated with nitrogen of domestic sewage. Nitrifying bacteria were counted by serial dilution and agar plates, and were isolated until obtaining axenic colonies. These were identified by biochemical batteries or genetic sequencing, and the quantification of their nitrifying capacity was obtained by the methods 4500-NH4 + -F and 4500-NO-2-B, all between September 26, 2011 and March 16, 2014. A total of seven strains of nitrifying microorganisms were isolated and purified, including four Streptomyces sp., one Pseudomonas putida, one Sphingomonas sp. and one Aeromonas sp. We found that there were 2.23 x 10 5 UFC/g of soil of ammonium oxidizing bacteria and 2.2 x 10 4 CFU/g of soil of nitrite oxidizing bacteria in the samples. The quantification of the nitrifying capacity of the strains by colorimetric methods, determined that the maximum ammonium removal capacity was 0.050 mg N/L/day and 0.903 mg N/L/day of nitrite. The collection of few strains of nitrifying organisms and a low CFU count, can be attributed to the technique used, since this only recovers 1 % of the microorganisms present in a sample, which, however, is acceptable for studies which main purpose is to obtain cultivable microorganisms. Future research should consider removal tests with higher ammonium and nitrite levels, to find the maximum capacity of the isolated microorganisms, and evaluate their potential use in wastewater treatment systems. Rev. Biol. Trop. 65 (4): 1527-1539. Epub 2017 December 01.
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