Direct counting of bacteria preserved with lugol iodine solution

Lugol iodine solution was compared with glutaraldehyde as a preservative for marine bacteria. Direct counts with the fluorochrome 4',6-diamidino-2-phenylindole show no significant difference between the preservatives, but the use of Lugol solution has several advantages over glutaraldehyde, especially in the handling and storage of samples. Bacteria were counted in water samples that were preserved with Lugol iodine solution and stored at room temperature for 4 years. Microprotozoa were also counted in samples preserved with Lugol iodine solution by using the fluorochrome fluorescein isothiocyanate.