Manganese (Mn2+) tolerance and biosorption by Meyerozyma guilliermondii and Meyerozyma caribbica strains.

Abstract

Bioremediation of manganese (Mn) is notoriously difficult to achieve because of the high stability of Mn2+ in aqueous solutions. Regarding the biotechnology strategies for removal of Mn from water, the use of bioremediation by bacteria and fungi is well known, but little is known about how yeasts can participate in this process. Hence, the study’s aim was to isolate yeasts with the ability to remove Mn2+, also elucidate the mechanism related to Mn bioremediation. Two kinds of yeast organisms were isolated from Brazilian mining water and identified as Meyerozyma guilliermondii and Meyerozyma caribbica by biochemical and phylogenetic analyses. Both isolates survived and their colonies grew in up to 32 mM of Mn2+, and they were able to remove 100% of Mn2+ from the culture medium in small-scale batch experiments conducted overall 1-week period. It was observed that for both isolates the removal of Mn is independent of pH. Analysis by SEM/EDX revealed that the Mn was adsorbed by the cell walls of M. guilliermondii and M. caribbica in the biosorption assays in the biological removal of bound Mn2+. These results demonstrated that both yeasts, with living and dead biomass, have an excellent Mn2+ ion biosorption capacity, as demonstrated by kinetic equations, in which M. caribbica showed a higher velocity when compared to M. guilliermondii. (respectively 1.088 and 0.324 mgMn day−1). Taken together, our results showed that these two yeasts isolates have potential roles in developing new biotechnology applications related to Mn bioremediation from waters contaminated with this persistent ion.