Macroalgas verdes como recursos sustentáveis: identificação, caracterização, exploração do potencial bioativo e o desenvolvimento de materiais celulósicos a partir da biomassa de Ulva sp. e Chaetomorpha sp. coletada em viveiros de aquicultura em Tibau do Sul, Brasil

Abstract

The growing demand for sustainable resources and the need to reduce environmental impact drive the search for new sources of renewable and versatile raw materials. In this context, marine macroalgae emerge as promising alternatives, offering applications ranging from the production of functional foods to the manufacture of packaging and biodegradable materials. Thus, this study investigated the biotechnological potential of the green macroalgae Ulva sp. and Chaetomorpha sp., collected in aquaculture ponds in the municipality of Tibau do Sul, Northeast Brazil, with emphasis on their physical-chemical, morphological characterization, bioactive, antioxidant, antibacterial properties and the use of fresh algae pulp as cellulosic materials. The identification at the genus level of the collected macroalgae was carried out, showing the presence of Ulva sp. and Chaetomorpha sp. which emerged spontaneously, without intentional cultivation. Physicochemical and phytochemical analysis revealed a profile rich in fibers, minerals and bioactive compounds, such as pigments, phenolic compounds and fatty acids, in the algal extracts. Methanolic extracts demonstrated greater efficiency in the extraction of bioactives and superior antioxidant activity compared to aqueous and ethanolic extracts, through pretreatment with ultrasound followed by a solid-liquid extraction. The methanolic extracts of Ulva sp. presented total phenolic contents greater than 7 mg GAE/100 g of oven-dried powder, while the extraction of pigments, total chlorophylls and carotenoids, presented 73 mg/g and 17.75 mg/g, respectively. The analysis of fatty acids in Ulva sp. detected essential compounds, such as palmitic acid and linoleic acid, highlighting the functional potential of these macroalgae. Antioxidant activity tests demonstrated the ability to capture free radicals using the DPPH and ABTS methods, with inhibition values of 20% in methanolic extracts, while assessments of the minimum inhibitory concentration indicated the effectiveness of methanolic and ethanolic extracts against Gram-positive and Gram-negative bacterias. Furthermore, among the polysaccharides extracted from both species studied, cellulose extracted from Chaetomorpha sp. presented an average yield of approximately 20%, twice as high as that extracted from Ulva sp., and a crystallinity index of approximately 90%, demonstrating the extraction of pure cellulose with the capacity to form cellulosic material from Chaetomorpha sp. with potential for packaging. These cellulosic handsheets exhibited promising characteristics, presenting an average thickness of 0.680 ± 0.130 mm and a surface structure with the presence of long, well-organized fibers, reinforcing the potential of this biomass as a cellulosic material. The results of this study highlight the value of green macroalgae as a sustainable and environmentally responsible resource, and also highlights its relevance for the advancement of the blue bioeconomy, promoting the appreciation of local marine biodiversity and contributing to the development of more sustainable solutions in various industries, including food, packaging, cosmetics and pharmaceuticals.