Contamination of aquaculture products by compounds that produce off-flavors is a major problem in the industry. When off-flavor is detected in fish, harvesting can be delayed, processing impeded, and if tainted fish reach the market, consumers may be dissatisfied and adverse to future purchases of the cultured species. Channel catfish farming represents the largest sector of the aquaculture industry in the U.S. with an annual production of over 200,000 tons. Off-flavor problems are estimated to cost channel catfish producers $15 - $23 million annually and to affect up to 70% of catfish operations. Bioluminescent bioreporters are bacterial strains that produce bioluminescence in response to specific chemicals. The purpose of this project is to develop a bioluminescent bioreporter to detect off-flavor compounds in water and to design a ready-to-use system for channel catfish farmers. The bioreporter system will allow rapid, inexpensive, and quantifiable detection of these compounds by farmers on the pond bank and by personnel in processing plants. This novel and innovative approach to managing off-flavor problems in aquaculture has potential to significantly decrease production costs and increase profits in the channel catfish industry. This system could also be used by suppliers of municipal drinking water and facilities storing agricultural grains where off-flavor compounds also cause a problem. OBJECTIVES: The occurrence of off-flavors in food and water intended for human consumption is an important limitation in many industries. Off-flavors affect profitability by decreasing consumer demand and increasing the cost of production, and considerable effort and expense is dedicated to eliminating the presence of improper tastes and odors in consumer products. The compounds, geosmin and 2-methylisoborneol (2-MIB), are produced by microorganisms in aquatic environments and are often attributed to off-flavor episodes in fish and drinking water. Off-flavors induced by 2-MIB and geosmin are a major problem (affecting up to 70% of producers) in the channel catfish industry and cost producers $15-$23 million annually. The objective of the proposed project is to develop a bacterial bioluminescent bioreporter to detect off-flavor compounds in water and to design a ready-to-use system for channel catfish farmers. The bioreporter system will allow rapid, inexpensive, and quantifiable detection of 2-MIB and geosmin by farmers on the pond bank and by personnel in processing plants. This novel and innovative approach to managing off-flavor problems in aquaculture has potential to significantly decrease production costs and increase profits in the channel catfish industry, and could also be used extensively by suppliers of municipal drinking water and facilities storing agricultural grains. APPROACH: The objective of this Phase I project is to design and construct a bacterial bioluminescent bioreporter to detect off-flavor compounds, specifically 2-MIB, and to demonstrate feasibility and potential for use in the channel catfish aquaculture industry. At the end of Phase I, a bioluminescent bioreporter strain will be completed and tested to determine the levels of detection of 2-MIB in water samples. Water samples will be collected from channel catfish ponds presenting off-flavor problems and will be tested by the bioreporter system. The technical feasibility of using a bioreporter to detect the off-flavor compound 2-MIB will be demonstrated by addressing several separate and distinct tasks. The specific tasks are: 1. Construct a bioluminescent bioreporter to detect 2-MIB. 2. Determine the analytical parameters of the bioreporter. 3. Evaluate performance of the bioreporter using collected aquaculture pond samples. 4. Evaluate the use of solid phase extraction membranes for concentration of 2-MIB 5. Identify and isolate a genetic element that is responsive to geosmin. 6. Prepare and submit the final report
