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Research Project: Management of Off-flavors and Undesirable Bacteria in Aquaculture

Location: Natural Products Utilization Research

Title: Temperature effects on biomass, geosmin, and 2-methylisoborneol production and cellular activity by Nocardia spp. and Streptomyces spp. isolated from rainbow trout recirculating aquaculture systems

Author
item Schrader, Kevin
item Harries, Marcuslene
item Page, Phaedra

Submitted to: Journal of Industrial Microbiology and Biotechnology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/11/2015
Publication Date: 2/28/2015
Publication URL: http://handle.nal.usda.gov/10113/60684
Citation: Schrader, K., Harries, M.D., Page, P. 2015. Temperature effects on biomass, geosmin, and 2-methylisoborneol production and cellular activity by Nocardia spp. and Streptomyces spp. isolated from rainbow trout recirculating aquaculture systems. Journal of Industrial Microbiology and Biotechnology. 42:759-767.

Interpretive Summary: Several types of bacteria that produce “earthy” and “musty” compounds which cause off-flavor in fish raised in recirculating aquaculture systems (RAS) were evaluated for the effects of different temperature on production of the off-flavor compounds. Results determined the specific species of bacteria as the likely main contributor for the off-flavor problems in the fish from the RAS.

Technical Abstract: Isolates of Nocardia cummidelens, Nocardia fluminea, Streptomyces albidoflavus, and Streptomyces luridiscabiei attributing to geosmin-related off-flavor in rainbow trout (Oncorhynchus mykiss) raised in recirculating aquaculture systems (RAS) were evaluated for the effect of temperature (10-30 degrees Celcius) on biomass, geosmin, and 2-methylisoborneol (MIB) production and cellular activity. Cultures of these isolates were monitored over 7 days by measuring culture dry weight, geosmin and MIB production using solid phase microextraction-gas chromatography-mass spectrometry (SPME-GC-MS), and ATP production via a luminometer. Compared to the other isolates, S. luridiscabiei had higher biomass (8.17 mg/mL) at 15 degrees Celcius (water temperature in the RAS) after 4 and 7 days incubation. In addition, S. luridiscabiei produced substantially higher geosmin (69,976.0 ng/L) at 15 degrees Celcius. All isolates produced MIB at 15 degrees Celcius but S. luridiscabiei produced substantially higher MIB (97,143.0 ng/L) and ATP at 15 degrees Celcius. Therefore, S. luridiscabiei appears to be the main contributor of geosmin and MIB in the RAS.