A 'culture' change in catchment microbiology?

Abstract

The development of a robust evidence base to inform policy and practice related to catchment microbial dynamics, water quality and human health must be grounded on proven techniques used for microbial water quality analysis. Currently, water regulators are in an exciting transition period with new techniques borne out of the ‘molecular revolution’ beginning to offer a means of characterising microbial watercourse pollution that challenge ‘tried and tested’ culture-based reference methods. In this commentary we advocate caution regarding the reliability of quantitative molecular tools and stress the need to continue programmes of cross-validation between enumeration approaches. In turn, novel detection (molecular) methodologies can be validated over time at the larger landscape scale (i.e. the scale at which the policy is implemented) against well-established ‘tried and tested’ (culture-based) reference methods. This will ensure that hydrologically relevant research and policy questions under consideration still deliver a demonstrable impact for regulators. Indeed, the current European Union (EU) legislation for the microbial quality of bathing and shellfish harvesting waters demands that specific standards are derived from culture-based criteria, highlighting the need to sustain such approaches without their complete abandonment in the face of emerging molecular detection techniques (CEC, 2006a,b). Thus, paradoxically, new molecular technology may compromise the development of the existing, and rather immature, evidence base of catchment microbial dynamics if cross-validation is not properly undertaken. The danger then is that molecular approaches could move on to become the ‘gold-standard’ without a thorough understanding of the implications for regulation and aspects of modelling and applied research required to meet current water policy frameworks.