01492nas a2200169   4500008004100000245014300041210006900184300001500253490000700268520092100275100001101196700001801207700001601225700001601241700001801257856004701275       1995                        eng d00aOptimal staining and sample storage time for direct microscopic enumeration of total and active bacteria in soil with two fluorescent dyes0 aOptimal staining and sample storage time for direct microscopic   a3367 -33720 v613 aDirect counting techniques, first developed for aquatic samples, can be used to enumerate bacteria in soil and groundwater sediments. Two fluorescent dyes, 5-cyano-2,3-ditolyl tetrazolium chloride (CTC) for actively respiring bacteria and 4(prm1),6-diamidino-2-phenylindole (DAPI) for total bacteria, were tested for their usefulness in epifluorescent direct bacterial enumeration in soil. Both dyes can be used for the same soil sample without affecting enumeration results. Staining for 8 h with CTC and for 40 min with DAPI resulted in maximum numbers of stained cells. The optimal DAPI staining concentration is 10 mg liter(sup-1). After preparation, slides should be stored at 4(deg)C and counted within 2 days for CTC and within 24 h for DAPI. Sodium PP(infi) or sodium chloride solutions were used to desorb bacteria from soil prior to counting. Counts were significantly higher when sodium chloride was used.1 aYu, W.1 aDodds, W., K.1 aBanks, M.K.1 aSkalsky, J.1 aStrauss, E.A.  uhttp://aem.asm.org/content/61/9/3367.short