ABSTRACT
The millenary activity of extracting heavy metals (HM) is nowadays considered to be one of the main economic activities of the world with México, Chile, China and Australia being some of the countries with higher productions. Due to their particular properties, HM were and still are, used in many industries and production activities. The impact of heavy metals in the diversity of microbial communities has been studied for several years. The methods used have evolved with the passage of time. Metals and metalloids can be classified into three categories according to their biological roles and effects on microorganisms Metatranscriptomics deals with the massive sequencing of the whole RNA of a microbial community and gives information on the genes that are expressed in certain conditions and time. Metagenomics, the massive sequencing of the microbial community DNA, can be applied to a specific gene, for example the 16S rRNA, or to the entire genetic material.
