Abstract
Harmful algal blooms (HABs) are the proliferation of toxic nuisance algae that cause a negative impact on natural resources or humans. Worldwide increases in the frequency, duration, and geographical distribution of HABs suggest that these species are becoming an increasingly important influence on the aquaculture industry, human health, coastal economies, and subsistence shellfish harvesters. Significant indirect impacts that promote critical habitat loss or disrupt the microbial food web balance also have been documented. Innovative methods for the detection and identification of toxic algal species are needed to meet increased demands for better monitoring of HABs and for understanding their causes and effects. A whole-cell biosensor using bioluminescent stress fingerprinting was developed for rapid detection and identification of harmful algae. Four toxic algal cultures, Karlodinium micrum, Pfiesteria piscicida, Chattonella marina and Prorocentrum minimum, collected from Chesapeake Bay were employed. Stress fingerprints were acquired upon contact with a panel of six bioluminescent strains containing selected stress-responsive E. coli promoters fused to the Photorhabdus luminescens luxCDABE reporter. These fusions are: recA-lux (in SOS regulon), grpE-lux (in heat shock regulon), katG-lux (in OxyR regulon), inaA-lux (in Sox and Mar regulon), yciG-lux (in sigma s-dependent stress response regulon), and o513-lux (in sigma s-independent, stationary phase inducible stimulon). The stress responsive signals emitted by the panel upon contact with toxic algae were distinctive for each toxic species. Characterization of bioluminescence enables quantification of stress fingerprints specific to the toxic algae, suggesting the potential of detecting the presence and severity of harmful algae in the coastal water.