Effect of pH on the tolerance towards As, Pb, Zn by microfungi isolated from mine tailings.
Effect of pH on the tolerance towards As, Pb, Zn by microfungi isolated from mine tailinEffect of pH on the tolerance towards As, Pb, Zn by microfungi isolated from mine tailings
Effect of pH on the tolerance towards As, Pb, Zn by microfungi isolated from mine tailings
Valeria-Sofia Hernandez1*,2, Patricia Velez2, Yunuen Tapia-Torres3, Bruno Chávez-Vergara4, Jorge Valdivia-Anistro5
1Posgrado en Ciencias Biológicas, Universidad Nacional Autónoma de México, Mexico City, Mexico
2Instituto de Biología, Universidad Nacional Autónoma de México, Mexico City, Mexico
3Escuela Nacional de Estudios Superiores Unidad Morelia, Universidad Nacional Autónoma de México, Michoacán, Mexico
4Departamento de Ciencias Ambientales y del Suelo, Instituto de Geología, Universidad Nacional Autónoma de México, Mexico City, Mexico
5Facultad de Estudios Superiores Zaragoza, Universidad Nacional Autónoma de México, Mexico City, Mexico
*E-mail: vasoherna99@gmail.com
Mine tailings generate from the residue of shredded rocks after minerals’ extraction. These residues are characterized by fluctuating and extreme pH values, low availability of nutrients, and the copious presence of toxic heavy metals, such as As, Pb, Zn. These metals cause the oxidation of nucleic acids leading to cell damage and alterations in DNA repair mechanisms. In the environment, they limit the accessibility to essential nutrients (N and P), altering ecosystem functions. The ability of fungi to tolerate toxic elements and to cope with fluctuating pH conditions promotes their occurrence in polluted environments, such as mine tailings, posing them as a suitable model for the remediation of heavy metals in mine tailings. Myco-remediation practices use fungi for the mineralization, transformation or accumulation of toxic metals. So, the objective of this research was to evaluate the effect of pH on the tolerance towards As, Pb and Zn on microfungi isolated from mine tailings (Aspergillus sp., Fusarium sp. and Purpurecillium sp.). Tolerance assays were performed by supplementing heavy metals (Na2HAsO4-7H2O, Pb (NO3)2, and Zn) to culture media in three different concentrations under two experimental pH conditions (3 and 8). Our results on the tolerance index indicated that fungi grew on culture media when supplemented with As, Pb, Zn in different concentrations particularly at pH 3. This finding indicates that acidic pH does not represent a detrimental factor for fungal growth. Our preliminary data confirm the potential of fungi in the bioremediation of heavy metals under fluctuating pH conditions in mine tailings.