Biopolymer production by rhizobacteria associated with Cactaceae

Bacterial biopolymers are biodegradable substances and sustainable alternatives to conventional polymers. Thus, they have been gaining prominence as sustainable alternatives to petroleum-derived polymers, promoting research aimed at optimizing their production and application in various industrial sectors. In this context, this study aims to select rhizobacteria from the Caatinga with the potential to synthesize exopolysaccharides (EPS) and define the optimal conditions for their production. Bacterial suspensions were inoculated on sterile filter paper discs on culture medium inducing EPS production. EPS production was determined by the formation of a mucoid layer and confirmed in the presence of absolute ethanol. The isolates that accumulated the highest amount of EPS were subjected to tests based on the Rotational Central Composite Design (RCCD), varying pH, temperature, and glucose as a carbon source. EPS recovery was evaluated in two treatments: static fermentation and under constant agitation. Among the 15 isolates selected, PH9.1 had the best performance in assay 13 (pH 7.0; temperature 38.5°C; glucose 1%), with a mucoid layer diameter of 2.15 cm, higher than the others. Moreover, static fermentation resulted in a higher yield of fresh (0.64 g) and dry (0.42 g) mass, standing out as the most efficient condition, which reinforces the biotechnological potential of Caatinga rhizobacteria for sustainable EPS production and boosts new industrial applications.