USE OF THE 5-CYANO-2,3-DITOLYL TETRAZOLIUM CHLORIDE REDUCTION TEST TOASSESS RESPIRING MARINE-BACTERIA AND GRAZING EFFECTS BY FLOW-CYTOMETRY DURING LINEAR ALKYLBENZENE SULFONATE DEGRADATION

Viable, total and metabolically active bacteria were determined during linear alkylbenzene sulfonate degradation in coastal seawater. Viable bacteria were estimated by plate counts on marine agar media while th e total and metabolically active bacteria were determined with the nuc leic acid stain SYTO-13 and the tetrazolium salt 5-cyano-2,3-ditolyl t etrazolium chloride, respectively, in double stain procedures analyzed by flow cytometry. The double stain SYTO-13/5-cyano-2,3-ditolyl tetra zolium chloride is a rapid and simple method that discriminates bacter ioplankton populations according to nucleic acid content and formazan formation. Linear alkylbenzene sulfonate degradation was monitored by high-performance liquid chromatography analysis. Bacterioplankton degr aded linear alkylbenzene sulfonate by growing to communities with a hi gh percentage of viable and metabolically active bacteria. The bacteri a produced were rapidly grazed by protozoa; however, the grazing took place mostly on metabolically active cells, which were larger than the rest of the population. (C) 1998 Published by Elsevier Science B.V. A ll rights reserved.