Caracterização molecular de arqueias em rejeitos siderúrgicos

Abstract

Mining and activities arising from it, such as steel, are considered crucial to economic development, but is responsible for many environmental damage. The steelmaking process generates 700 kg of wastes per ton of steel and these tailings have high concentrations of undesirable metals, which hinder their recycling, with a negative impact on the economy and environment. The microbial diversity of environments impacted by human activities has been widely studied due to the possibility of recovery of various metals as also the environment. Using an independent approach to cultivating the present study investigated the diversity of wastes in steel arches, newly produced (RRP) and deposit (RD) four years ago in an area adjacent to the steel industry. The clone libraries of the 16S rRNA gene of the archaea were constructed from environmental DNA of these tailings. The 158 sequences from clone libraries constructed from the two tailings were grouped into 14 OTUs (operational taxonomic unit), 13 of RRP and only one RD. Phylogenetic analysis of gene fragments of 16S rRNA of archaea revealed that OTUs were affiliated to three phyla: Crenarchaeota represented in both libraries, while Euryarchaeota and were Thaumarchaeota exclusive library RRP. The Shannon diversity index and Simpson showed limited archaeal diversity, although the library RRP present greater diversity compared with RD. Only one OTU found in RRP was identified at the species level, being affiliated with Halobacterium salinarum species, found in extremely salty. Furthermore, an OTU affiliated with Thaumarchaeota was identified in the family level, Cenarchaeaceae which has members that play a fundamental role in the nitrification. Moreover, the great majority of OTUs of RRP may represent new classes of these three phyla. The only OTU found in RD was affiliated with a crenarchaea uncultivable. The analysis revealed PCRq greater abundance of archaea in RRP and bacteria in RD. Therefore, the data obtained demonstrate the diversity of archaea in these two types of tailings. This study provides the first information about the phylogeny of archaea in steelmaking wastes, opening new perspectives for studies on the structure and function of archaea indigenous communities in this environment, and possibly establish possible mechanisms and cycle chemicals.