Hello Julie: We do a lot of work with freshwater bacteria and use DAPI, Hoechst 33342, SYBR Green I, Syto 13, all with good results, even for very small bacteria. I realized that some stains are particularly sensitive to pH. Our formol fixed samples often have a pH below 4.5. So we usually add a small amount of Na-citrate/K-citrate buffer to the sample prior to staining in order to bring the pH to about 7.5, where most fluorescent dyes work very good. Maybe you should measure the pH in your samples. Best luck Stefan Julie Hall wrote: > > I have just been working with a student who is wanting to count > bacteria from estuarine and coastal samples from oyster feeding > experiments. We use SYBR Green II to count bacterial samples from > the open ocean and have had few problems with separating the > population from background. With the estuarine and coastal samples > with SYBRII the background noise is elevated and differentiating the > population becomes difficult. > > Any body used a more effective stain or found a better way of > approaching this??? > > Julie > ---------------------------------- > Julie Hall > Manager > Aquatic Ecology and Laboratory Services > NIWA, Box 11-115, Hamilton, NZ > Ph. +64-7-856 1709 Fax +64-7-856 0151 > eMail j.hall@niwa.cri.nz -- ------------------------------------------------- Stefan Andreatta Institute of Zoology and Limnology University of Innsbruck, Austria phone: ++43-512-507-6122; fax (..)-2930
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