Effects of BG11 and CHU nutrient media on the laboratory cultivation of Nostoc cf. punctiforme: implications for sustainable production of an Andean bioresource

Nostoc cf. punctiforme, a filamentous cyanobacterium traditionally consumed in the Andean region, is valued for its high nutritional content and its potential for sustainable aquaculture. However, increasing demand for this organism has intensified the harvesting pressure on natural populations. Cultivation strategies that improve biomass production under controlled conditions may contribute to reducing this pressure and supporting conservation-oriented management. In this study, under controlled laboratory conditions we evaluated the effects of different concentrations of BG11 and CHU culture media on the growth and biomass production of Nostoc cf. punctiforme. Nine treatments were tested, including a control without nutrients (T0) and four concentrations of each culture medium (25%, 50%, 100% and 125%). The cultures were maintained for 35 days in both liquid and solid media, and growth performance was assessed through wet weight, dry weight and, in liquid cultures, specific growth rate. In solid medium, the highest wet biomass was observed in treatments T3 (100% BG11) and T8 (125% CHU), reaching 2.09 g and 2.87 g, respectively. In liquid medium, treatment T2 (50% BG11) showed the highest biomass production, with an average of 1.18 g and a specific growth rate of 2.77 % d⁻¹. In contrast, the control treatment exhibited the highest dry-matter fraction, suggesting differences in water content or extracellular matrix organization among treatments, rather than higher biomass productivity. Although nutrient enrichment improved growth-related variables in several treatments, it was also associated with a reduction in the occurrence of intact colonies. These results indicate that nutrient enrichment significantly influences biomass production, growth dynamics and colony stability in Nostoc cf. punctiforme. Therefore, the evaluated conditions provide preliminary laboratory-scale evidence for controlled cultivation, although colony integrity will need to be improved before pilot-scale production systems can be proposed.