Graduation date: 2007
The microbial loop plays a crucial role in remineralization of organic matter and fuels recycled production in the aquatic environment. The capability of microbes to utilize particular compounds can be examined through their ectoenzyme (found outside the cell) activities using fluorogenic substrate analogs. These catalysts hydrolyze polymers otherwise too large for cell uptake, and this activity can act as an indicator of the nutritional needs of a microbial community. This thesis describes a new flow-through instrument developed for automated measurement of in-situ rates of microbial ectoenzyme activity intended for use at cabled coastal ocean observatories. This system, the Multiple Enzyme Analyzer (MEA), functions by assaying up to four different ectoenzyme activities in seawater via separate flow channels by quantifying changes in fluorescence at specific wavelengths over time. Details of design, comparisons of performance with laboratory fluorometers, an exploration of instrument and reagent stability, and a preliminary experiment from a seawater tank at Hatfield Marine Science Center in Newport, OR are addressed. These results demonstrate that MEA is capable of
detecting variable ectoenzyme activity in seawater. Future strategies for the first coastal deployment of MEA are also discussed in the context of the Long-term Ecosystem Observatory (LEO-15) operated by Rutgers University.