Bioprospecção de uma cianobactéria isolada no rio Joanes/BA para síntese de produtos visando aplicações biotecnológicas

Abstract

Cyanobacteria represent the most diverse group of photosynthetic organisms on the planet and hold high potential for the discovery of novel bioactive compounds. Their pigments have well-established applications in food and nutraceutical products and also serve as valuable sources of proteins and other biomolecules. These characteristics broaden their potential use in sectors such as biofuels, food, animal feed, and, more recently, in the emerging field of phyconanotechnology. In this context, the aim of this study was to isolate a cyanobacterial strain from a river located in northeastern Brazil, analyze its potential for cyanotoxin production, and evaluate its application potential for obtaining bioproducts such as phycocyanin and carotenoids, as well as for the synthesis of carbon dots from laboratory-cultivated biomass and post-extraction residual biomass. The strain was isolated using a thermal method. Identification was carried out through a polyphasic approach, and cyanotoxin production potential was assessed by molecular and chemical methods (PCR and LC-MS²). Cultivation and growth kinetics were conducted under controlled temperature and light conditions to produce biomass, which was subsequently used for phycocyanin extraction, carotenoid identification, and carbon dot synthesis from residual biomass after bioactive extraction. The isolated and laboratory-cultivated strain was identified as Leptolyngbya boryana and was non-toxigenic. Phycocyanin extraction followed a protocol combining different solvents with freeze–thaw cycles. The most efficient extraction method employed calcium lactate at pH 9.47, yielding the highest phycocyanin content (153.24 mg/g of biomass). HPLC analysis revealed the presence of echinenone and chlorophyll a homologs in the biomass. Additionally, carbon dots were synthesized via a hydrothermal process from the cultivated species’ biomass (both before and after bioactive extraction), as well as from Chlorella vulgaris for comparison. Characterization of the carbon dot nanomaterials showed high fluorescence, photostability, and consistent performance in potential applications such as bioimaging, fluorescent sensors, and optoelectronic devices. Overall, the results indicate that the identified L. boryana strain possesses significant biotechnological potential, both for the production of phycocyanin and carotenoids and for the generation of nanomaterials of interest, highlighting the prospects for valorizing biomass into high-value products and commercial applications.