Bivalent copper ions presence triggers removal and homeostatic mechanisms in the metal-resistant microorganism Apiotrichum loubieri M12

BONILLA, JOSÉ OSCAR; CALLEGARI, EDUARDO ALBERTO; PAEZ, MARÍA DANIELA; GIL, RAÚL ANDRÉS; VILLEGAS, LILIANA BEATRIZ

RESEARCH IN MICROBIOLOGY

ELSEVIER SCIENCE BV

Año: 2022

0923-2508

Extreme environments are promising sites to isolate heavy metal-resistant microorganisms. The present work aimed to isolate and study a microorganism capable to remove heavy metals, from sediments of an Acid Mine Drainage-affected environment located in San Luis (Argentina). Apiotrichum loubieri M12 was selected for its ability to tolerate heavy metals. The microorganism was able to remove 30-35% of copper from liquid media when faced to 40 µg mL-1Cu(II). The analysis of the biomass exposed to the metal through SEM-EDS showed uniform bioadsorption of the metal on the cell surface (4.09% w/w) and variations in the proportion of other biomass constituent elements. Proteomics revealed that the presence of Cu(II) induces differential expression of intracellular proteins involved in a wide variety of metabolic processes. Interestingly, a specific response to the metal was detected in cell-free supernatants, in which copper binding proteins were identified. A large number of proteins with metal ion binding sites were detected both at the intra and extracellular levels. The readjustment of protein expression is crucial to counteract the metabolic imbalances produced by the metal and to sequester and transport copper, being fundamental to reduce the toxic effects that Cu(II) could exert on the cell.