Characterization of protein and small molecule profiles in wastewater by mass spectrometry for wastewater based epidemiology and water quality monitoring

Abstract

Introduction Wastewater-based epidemiology (WBE) is a powerful approach to assessing the health and lifestyle of a population. In this study, a comprehensive characterization of proteins, pesticides and pharmaceuticals in the influent and effluent waters of several WWTPs has provided new potential markers for industrial and living activities (1). These compounds can also give a more thorough evaluation of WWTP treatment. This is routinely evaluated through bulk parameters such as chemical and biochemical oxygen demand. However, with a plethora of dynamic and changing conditions linked to water practices, the diagnosis of water quality based on this data is far from optimal.

Methods We studied the protein and small molecule composition in the influent and effluent waters of 3 WWTP in Catalonia which serve communities of different population and industrial profile. Water samples (24-h composites) were filtered and the soluble part was submitted to the different analysis. Proteins in the water samples were concentrated in a SDS-PAGE gel, digested with trypsin and analyzed by HR-LC-MS/MS. Database protein identification was done using the complete Uniprot database and a semiquantitative analysis was performed based on the area of the unique peptides of each protein (1). Small molecules were obtained through different solid phase extraction methods targeting more than 140 micropollutants, including pesticides, pharmaceuticals and antibiotics (2). Extracts were analyzed by LC-QqQ.

Preliminary data We have identified hundreds of proteins from different species including human, livestock and bacteria. Our data provide a comprehensive semiquantitative description of wastewater proteins and their distribution among different organisms. Most proteins originated from main sources: excreta (urine and feces) from humans, and blood and other residues from livestock. Species-specific protein forms allowed obtaining separate profiles for species such as rat, mouse, cattle, pigs, and poultry. This capability provided useful markers of industrial activity in the areas studied. The integration of the protein and small molecule data (pharmaceuticals) reveals relations between the origin of the proteins and some drugs. For example, the amount of proteins derived from livestock correlates with higher levels of veterinary antibiotics. Our findings also provide new insights into the characterization of wastewater proteomics that allow for the proposal of specific bioindicators useful for practical purposes related to wastewater-based environmental monitoring and wastewater treatment plant management. Some relevant examples include Immunoglobulins and amylases for mammalian population monitoring (applicable, for instance, to rodent pest surveys) and albumins as indicators of the cattle processing industry. This study also provides of a full set of complementary information that can increase the understanding of the processes happening at the water treatment plants. This data will be very valuable to implement new control methodologies in the WWTPs and to investigate the effect of wastewater discharge in environmental buffers but also to identify contaminants that have been so far overlooked but are persistent or formed at a significant concentration

Novel aspect Monitoring proteins and pharmaceuticals will generate complementary and unique data that will help understanding population characteristics and evaluate wastewater treatments.