International Journal of Hygiene and Environmental Health 213 (2010) 437–443 Contents lists available at ScienceDirect International Journal of Hygiene and Environmental Health journal homepage: www.elsevier.de/ijheh Assessment of perchlorate-reducing bacteria in a highly polluted river Giovanni Vigliotta a , Oriana Motta b,∗ , Francesco Guarino a , Patrizia Iannece a , Antonio Proto a a Department of Chemistry, University of Salerno, via Ponte don Melillo, 84084 Fisciano, SA, Italy b Department of Educational Science, University of Salerno, via Ponte don Melillo, 84084 Fisciano, SA, Italy article info Article history: Received 10 February 2010 Received in revised form 29 July 2010 Accepted 3 August 2010 Keywords: Sarno River Perchlorate reduction Dechlorospirillum Dechlorosoma PCR abstract A 1-year monitoring experiment of the Sarno River basin was conducted during 2008 to evaluate the overall quality of the water over time and to compare the results with those obtained previously. The physico-chemical and microbiological characteristics of the water course had not changed appreciably with respect to previous determinations, thus emphasizing the major contribution of untreated urban wastewater to the overall pollution of the river. Moreover, attention was paid to the perchlorate ion, one of the so-called emerging contaminants, which is widespread in natural environments and is known to have adverse effects on the human thyroid gland. Over the entire monitoring program, we did not find apprecia- ble levels of perchlorate, although the particular environmental condition could support its development. Thus, a dedicated study was designed to assess the presence of bacteria that can reasonably reduce per- chlorate levels. By enrichment and molecular procedures, we identified - and -Proteobacteria strains, classified by 16S rDNA sequences as Dechlorospirillum sp. and Dechlorosoma sp., respectively. Further physiologic characterization and the presence of the alpha subunit gene (pcrA) of the perchlorate reduc- tase in both strains confirmed the presence in the river of viable and active perchlorate dissimilatory bacteria. © 2010 Elsevier GmbH. All rights reserved. Introduction In a previous work, we reported the results of a 1-year mon- itoring study of Sarno River water quality. We identified high anthropogenic activity as the predominant source of microbial con- tamination, whereas chemical contamination was mainly related to uncontrolled release of polluting materials as well as to byprod- ucts of the wastewater treatment plant (WWTP) located along one of the tributaries (Motta et al., 2008). The river and its tributaries are used extensively as sources of irrigation water for the intensive agricultural activity in the basin. Therefore, contamination of the river, for which the indiscriminate increase in pollution factors has made natural purification capac- ities insufficient, is of particular concern to public health. Many years after the Ministry of the Environment declared the area to be at high environmental risk (Ministry Council, 1994), it was found that adequate chemical and bacteriological data to support this claim were almost completely absent. A further 1-year monitoring study of the Sarno River basin was conducted during 2008 to evaluate the overall water quality over time. Moreover, attention was paid to the perchlorate ion, one of the so-called emerging contaminants because the characteristic pollu- ∗ Corresponding author. Tel.: +39 089 963083; fax: +39 089 963083. E-mail address: omotta@unisa.it (O. Motta). tion and the particularly anoxic condition of the river suggested it could be present. The importance of perchlorate in the environment was first noted in the United States because of the high concentration of military and spatial activities, especially in areas of Southwestern states such as Nevada, Utah and California where contamination levels in many rivers and water wells used for human consump- tion and rural uses reached values associated with adverse health outcomes (Kirk, 2006; NRC, 2005; Renner, 1998). Health concerns mainly arise from the ability of perchlorate to disrupt thyroid gland utilization of iodine in metabolic hormones, which could affect normal metabolism, growth and development (Greer et al., 2002; Wolterink et al., 1998; Xu et al., 2003). Perchlorate is a ubiquitous salt that is released into the environment by both anthropogenic and natural sources. Anthropogenic perchlorate sources include military and commercial application of perchlorate salts as oxidiz- ers in propellants, flares, munitions, matches, fireworks, blasting agents and other materials. Although the natural occurrence of per- chlorate is poorly understood and the exact role of atmospheric processes in the formation of perchlorate remains uncertain, recent studies have demonstrated that significant quantities of perchlo- rate can form naturally in the atmosphere, especially during thunderstorms (Dasgupta et al., 2005; Parker et al., 2008). However, it has also been demonstrated that the perchlorate concentration ultimately occurring in groundwater is mitigated by factors such as hydrologic balance and microbial reduction (Plummer et al., 2006). 1438-4639/$ – see front matter © 2010 Elsevier GmbH. All rights reserved. doi:10.1016/j.ijheh.2010.08.001