Microbial diversity and contamination in Reconquista River sediments: culture dependent and independent approach to detect microorganisms with potential biotechnological applications

PORZIONATO NATALIA; AGUSTINA ZILIANI; CELESTE GRIMOLIZZI; ANA TUFO; SUSANA VAZQUEZ; ANGELA CABEZAS; GUSTAVO CURUTCHET

Simposio; The Sixth International Symposium on Environmental Biotechnology and Engineering; 2018

Sediments from contaminated water courses accumulate large amounts of organic matter and toxic persistent pollutants like heavy metals and pesticides. The stress caused by severe contamination leads to the selection of microorganisms which, in addition to being involved in in situ self-purification processes, have a clear biotechnological potential. In this work, we studied the microbial communities from fluvial sediments in areas with different degree and type of contamination at the Reconquista River basin, one of the most polluted watercourses in the metropolitan area of Buenos Aires, Argentina. The sediment samples were analyzed to determine their physicochemical parameters and respirometry experiments were performed. Bacterial community structure in sediment samples was analyzed through 16S rRNA gene amplicon sequencing (V4 variable region, Illumina MiSeq platform, and data were processed using Mothur and R packages). Cultures were performed to enrich in sulphate and iron reducers and sulfur and iron oxidizers using selective media, and isolates were obtained in solid media. Taxonomic identification of isolates was achieved by partial sequencing of the 16S rRNA gene after DNA extraction using the Wizard® Genomic DNA Purification Kit (Promega) and PCR amplification using the universal primers 27F/1492R for bacteria and ITS1/ITS5 for yeasts. Growth kinetics and metabolites production was studied for the enrichment cultures and isolates obtained. Bacterial communities from areas with different contamination status differ in their structure (and therefore, in their functional potential and performance). Aerobic and anaerobic isolates, affiliated to Acidithiobaclllus, Clostridium, Desulfovibrio, and Shewanella among others, were obtained. These microorganisms possess a great potential for applications in environmental biotechnological processes.