Geosmin-producing species of Streptomyces and Lyngbya from aquaculture ponds

Abstract

Water and sediment samples collected monthly from six aquaculture ponds in east-central Alabama were analyzed for the presence of actinomycetes and cyanobacteria capable of producing geosmin and (or) 2-methylisoborneol, which cause earthy–musty off-flavors in fish. Six actinomycetous isolates were identified as geosmin producers, five of which were capable of producing 2-methylisoborneol. The one actinomycetous isolate producing geosmin but not 2-methylisoborneol was identified as Streptomyces halstedii. Only one of several cyanobacterial isolates was found to produce geosmin. This isolate was identified as Lyngbya cf. subtilis and was prevalent throughout the sampling period in a pond with a history of off-flavor problems. None of the cyanobacterial isolates produced 2-methylisoborneol in laboratory culture.Key words: geosmin, Streptomyces, Lyngbya, off-flavor, aquaculture.