Diversity and potential of the mobilome present along the Tietê river basin.

Author(s)

Luiz Ricardo Olchanheski

• Document type: Doctoral Thesis
• Press: São Paulo.
• Institution: Universidade de São Paulo (USP). Instituto de Ciências Biomédicas (ICB/SDI)
• Defense date: 2019-03-15

Examining board members

Welington Luiz de Araujo; Leticia Veras Costa Lotufo; Valeria Maia Merzel; Maria Inês Zanoli Sato

• Advisor: Welington Luiz de Araujo; Fernando Lucas de Melo

Abstract

Freshwater systems have vital importance for the livelihood of the population, in addition to contributing to agricultural production and industrial processes. Changes in physical-chemical characteristics in freshwater environments directly influence bacterial diversity, but little is known about the impacts on the functional profile in the bacterial community. Thus, one of the initial objectives of this work was to assess the correlation of the functional profiles in ten samples with different geographic positions and physical-chemical characteristics. From these analyzes, it was possible to verify that the geographical position is not correlated with the functional profile in the bacterial communities. In addition, salinity and genes for sulfur metabolism are the main characteristics that influence the functional profile. With the objective of analyzing the mobilome profile in detail using plasmid metagenome analysis, two points of the Tietê river were used as the object of study. The Tietê river, located in the state of São Paulo (Brazil), runs 1,136 km. Along this route, the river passes through several preserved areas of the Atlantic Forest and metropolitan regions, such as the city of São Paulo where the river receives a large amount of industrial pollutants and domestic sewage. The two points sampled are contrasting when compared to the IQA, one being classified as bad and the other as optimal. The genes present in plasmids at the point with greater anthropic activity were related to the functions of transmembrane transporters, efflux pumps, and genes that confer resistance to xenobiotic compounds and heavy metals, which confer adaptive advantages mainly the presence of toxic compounds. At the point of low pollutants, the genes of greater abundance are involved in the transport and assimilation of substances found in low concentrations, such as phosphorus. Also, with respect to the point with lower anthropogenic activity, the possible hosts more abundant belong to the phylum Cyanobacteria, which justifies the presence of more genes aimed at photosynthesis in plasmids. Also, in the Tietê river, it was possible to estimate the diversity of genes that confer resistance to antibiotics in four contrasting points when compared to the IQA. Higher abundance of genes that confer multidrug resistance at point with optimal IQA, and genes for resistance to sulfonamides at the point with poor IQA were observed. It was observed that the presence of heavy metals correlates with the increase of genes that confer resistance to antibiotics, determining a situation of co-selection of these genes. Metagenomic analyzes helped to understand how environmental characteristics modulate functional diversity in the bacterial community, as well as determine the selection pressure for laterally transferable genes, such as plasmids. (AU)

• FAPESP's process: 14/09692-5 - Diversity and biotechnological potential of the mobilome present in the Tietê River Basin
• Grantee: Luiz Ricardo Olchanheski
• Support Opportunities: Scholarships in Brazil - Doctorate