No abstract

No abstract

SUMMARYALipomyces sp. of soil yeast, probably of the ' starkeyi' or 'lipofer ' type, degraded paraquat over a wide range of pH and temperatures, extreme values of which reduced growth but not paraquat degradation. The organism withstood high concentrations of the herbicide.Growth in nitrogen-depleted broth amended with paraquat showed a lag phase of about 24 h. There was no lag with (NH,),SO, either alone or with paraquat, but in the latter case paraquat degradation was delayed for 24 h.A 24 h exposure to paraquat and a carbon source was necessary for synthesis of the paraquat-catabolizing system.The organism grew well on soil extract and malt extract and media containing (NH,),S04 or NH,N03 as nitrogen sources; it grew with urea or NaNO, after a lag of 24 h or longer, but not on biuret or NaNO,. Atmospheric N, was fixed in the presence of added molybdate. The presence of alternative nitrogen sources did not prevent or delay paraquat degradation.A variety of mono-, di-and polysaccharide materials was used as carbon and energy source. Growth was not obtained with powdered cellulose, carboxy-methylcellulose, lactose or paraquat as sole carbon source. The organism was unable to ferment carbohydrates or degrade paraquat anaerobically; it degraded commercial formulations of paraquat, but growth and degradation were affected by increasing concentrations of formulating additives.

No abstract

No abstract