EFFECT OF ARSENIC ON MICROORGANISMS AND BIOFILMS IN MIC OF WATER NETWORK MATERIALS

RASTELLI S.E.; VIERA M.R. ; ROSALES B.M.

Porto Alegre

Simposio; 8th Latin American Biodeterioration and Biodegradation Symposium; 2013

Inetrnational Biodeteriration and Biodegradation Society, Federal University of Rio Grande do Sul

During water distribution operation, tubing material is submitted to permanent contact with aquatic microbial species. They colonize the network surface forming biofilms which frequently cause corrosion on metallic substrata. On the other hand, the presence of arsenic in natural waters is a serious global problem due to its adverse impact on human health. However there are many microorganisms able to tolerate or metabolize this contaminant. In this work, different materials commonly found in water distribution networks (Fe, Zn, Cu and polypropylene) were submerged in waters with and without arsenic. The main objectives were: 1) To study the influence of As on the microbial communities developed on different substrata applying molecular techniques (PCR-DGGE) and their correlation with the deterioration of the substrata using microscopic techniques (SEM, ESEM) in an ample range of magnification; 2) To study the influence of high As(V) concentrations (50 to 1,000 mg/L) on the sessile microbial communities developed on each substratum. All the materials revealed very different behaviors which were not influenced by the presence of arsenic. Fe and Zn presented hemispherical localized attack with corrosion products accumulated at the bottom, while Cu exhibited localized attack revealing the alloy crystallography. PP samples did not reveal any biodegradation damage associated to the bacterial biofilm settlement. The DGGE band pattern of the biofilm communities was different for each material, and it was not affected by the presence of As(V). Culturing of sessile communities, even in the presence of high As(V) concentrations allowed the recovery of bacterial populations which were not detected in the source samples, thus a higher diversity was observed in all the cultures.