Rapid Detection and Monitoring of Flavobacterium psychrophilum in Water by Using a Handheld, Field-Portable Quantitative PCR System

Abstract

Advances in technology are making it easier for rapid field detection of microbes in aquaculture. Specifically, real-time quantitative PCR (qPCR) analysis, which has traditionally been confined to laboratory-based protocols, is now available in a handheld, field-portable system. The feasibility of using the Biomeme handheld qPCR system for rapid (<50 min) on-site detection and monitoring of Flavobacterium psychrophilum from filtered water samples was evaluated. Paired water samples were collected over a 23-d period from microcosm tanks that housed fish injected with known levels of F. psychrophilum. Water samples were filtered through 0.45-μm nitrocellulose filters and were analyzed with both the Biomeme qPCR platform and a traditional bench qPCR protocol. The two methods identified similar fluctuations in F. psychrophilum DNA throughout the study. Standard curves relating quantification cycles to the number of F. psychrophilum colony-forming units (CFU) were constructed and analyzed; results indicated that CFU increased rapidly between days 6 and 8 of the trial and then progressively decreased during the remaining 15 d. Average calculated log10(CFU/mL) values were significantly correlated between the two platforms. Rapid, field-based qPCR can be incorporated into daily water quality monitoring protocols to help detect and monitor microbes in aquaculture systems.