Utilization of multiple organisms in a proposed early-warning biomonitoring system for real-time detection of contaminants: preliminary results and modeling.

During past decades, biomonitors were deployed in lakes and rivers to rapidly detect hazardous chemicals by measuring the endpoints of a single aquatic species at defined short intervals. Most biomonitors, however, are only capable of indicating a departure from baseline water conditions without identifying the cause. In order to provide a more comprehensive assessment, a biomonitoring system which features a library of stereotyped responses of multiple aquatic species in various water conditions is proposed. A preliminary library was constructed by characterizing the behavioural and physiological responses of Daphnia magna, Hyalella azteca, Lumbriculus variegatus, and Pseudokirchneriella subcapitata to various concentrations of atrazine and tributyltin. By employing multivariate statistical tools such as principal component analysis (PCA) and discriminant analysis, this library (which contained responses after 6h of exposure to contaminants) was used as a template to classify and to model other sets of earlier measurements at 2 and 4h, resulting in an accuracy of 73 and 97%, respectively. These findings demonstrated the potential capability of the proposed early-warning biomonitoring system to provide real-time water quality assessment and early-warning contaminant detection.

Evaluation of low-copy genetic targets for waterborne bacterial pathogen detection via qPCR.

Recent developments in water quality research have highlighted difficulties in accurately predicting the incidence of pathogens within freshwater based on the viability, culturability and metabolic activity of indicator organisms. QPCR-driven assays are candidates to replace standard culture-based methods, however, protocols suitable for routine use have yet to be sufficiently validated. The objective of this study was to evaluate five oligonucleotide primers sets (ETIR, SINV, exoT, VS1 and ipaH2) for their potential applicability in qPCR assays to detect contamination from five waterborne bacterial pathogens (Escherichia coli O157:H7, Salmonella Typhimurium, Campylobacter jejuni, Pseudomonas aeruginosa, and Shigella flexneri). An enrichment-free qPCR protocol was also tested using S. Typhimurium-seeded source water, combining membrane filtration and mechanical, chemical and enzymatic lysis techniques to recover the bacterial cells. All five primer sets were found to have high specificity and sensitivity for the tested organisms. Four of the primers were able to detect pathogen loads as low as 10 cells/mL while 200 cells/mL of C. jejuni were detectable in pure culture. Although sensitivity decreased in an artificially contaminated environmental matrix, it was still possible to detect as few as 10 S. Typhimurium cells without enrichment. The primers and protocols evaluated in this study have demonstrated potential for further validation for possible application alongside traditional indicator techniques.