Start Date: Mar 01, 2009
End Date: Feb 28, 2011
In order to identify geosmin and methylisoborneol (MIB)-producing microorganisms, biosolids (organic matter) samples from the RAS will be used to inoculate various types of media that can support the growth of certain types of microorganisms known to be capable of geosmin and/or MIB production. Geosmin and MIB production by microbial isolates producing earthy-musty odors will be confirmed by instrumental methods. Instrumental analytical methods [solid phase microextraction and gas chromatography-mass spectrometry (SPME-GC-MS)] will be used to identify and quantify levels of the common microbial metabolites geosmin and 2-methylisoborneol (MIB) responsible for “earthy” and “musty” off-flavors, respectively, in the following: 1) microbial isolates identified as producing earthy and/or musty odors; 2) water and biosolids samples obtained from within the RAS; and 3) the flesh of barramundi from the RAS. The conditions required to increase depuration rates or enhance removal of common off-flavor compounds from barramundi will be determined through depuration studies that include instrumental analysis of fish fillets. The evaluation of management methods for reducing common off-flavor compounds in RAS will include monitoring the effects of the addition of oxidizing agents (e.g., hydrogen peroxide) on levels of off-flavor compounds in the water and subsequently in the flesh of barramundi.