Brazilian mangrove sediments as a source of biosurfactant-producing yeast Pichia pseudolambica for bioremediation.

This work highlights the biosurfactant production potential of yeasts from mangroves in northeastern Brazil. The biosurfactants were evaluated by their emulsifying capacity (EI24), with 6 isolates showing values between 50% and 62%. Surfactant properties from crude extract were measured using drop collapse, oil displacement, Parafilm® M, surface tension and critical micellar concentration tests. The effects of temperature, salinity, pH, and the ability to emulsify different hydrocarbons were analyzed, showing a promising potential of the yeast species investigated to tolerance to high temperatures and acidic pH, in addition to emulsifying different sources of hydrocarbons with environmental impact. It is important to note that the Pichia pseudolambica isolates showed a remarkable ability to reduce the surface tension of water, from 70.82 mN/m to 36.47 mN/m. In addition, the critical micellar concentration (CMC) values ranged from 7 to 16 mg/mL, highlighting the promising surfactant activity of these isolates for future applications. It was identified that the biosurfactant adhered to the yeast cell wall, and FTIR and 1H NMR spectroscopy analysis was carried out on the yeast biomass and its post-sonication supernatant. The results indicate the presence of characteristic functional groups and peaks found in biosurfactants of a glycolipid nature. Taking together the results reveals the promising potential of biosurfactant biosynthesis of P. pseudolambica yeast, a trait not reported in the literature so far for this species. P. pseudolambica presents a relevant metabolic potential for alternative substrate use and resilience to adverse conditions that could enable it to produce biosurfactants for the biotechnological remediation of areas contaminated by oil derivatives. The metabolic properties herein investigated, together with their presence in Brazilian mangroves, make P. pseudolambica an emerging candidate for developing industrial processes and sustainable strategies for the recovery of ecosystems impacted by oil spills, being positioned as a sustainable alternative to conventional surfactants.