The effect of the form and concentration of nitrogen on geosmin production by an aquatic actinomycete (streptomyces isolate WM1C1).

Abstract

Actinomycetes are organisms that produce geosmin which is one of the organic compounds responsible for the earthy (musty) odor in water. This study was designed to isolate an actinomycete, confirm it as a geosmin producer, and determine the effects of the form and concentration of nitrogen on the production of geosmin by the isolate. Five actinomycetes were isolated from the muds of Lake Waco; four were identified as Streptorayces and one as a possible Nocardia sp. or Micromonospora sp., and two Streptomyces spp. were confirmed to be geosmin producers by GC-MS. The effects of nitrogen on one Streptomyces sp. were reported as affecting threshold odor number (R.O.N.), biomass production (mg dry wt),

and Specific T.O.N. (T.O.N.-mg dry wt ^). The forms of nitrogen used were NO^-N as KNO^, NH^-N as NH^Cl, and organic nitrogen (ORG-N) as asparagine and the concen- tration range of nitrogen was 0.000 mg'L to 0.600 mg * L. T.O.N. values increased linearly as concentrations of NO^-N and NH^-N increased while ORG-N (0.300 mg'L inhibited geosmin production. Biomass production increased linearly as concentrations of NO^-N and ORG-N increased (0.000 mg*L ^ to 0.600 mg'L"'*") but low concentrations of all three nitrogen forms did not promote significantly larger biomass proudction than the nitrogen-free media. Specific T.O.N. increased as concentrations of NH^-N and NO^-N increased with NH^-N producing significantly higher Specific T.O.N. per flask.