Detection of bacterial contamination in starch and resin-based papermaking chemicals using fluorescencce techniques

Liisa Nohynek (Corresponding Author), Eija Saski, Auli Haikara, Laura Raaska

    Research output: Contribution to journalArticleScientificpeer-review

    9 Citations (Scopus)


    Rapid fluorescence techniques were evaluated for the detection of bacterial contaminants in papermaking chemicals including starch and the resin-based sizes and starch slurries used in the paper industry. Viable and non-viable bacterial cells were visualised by fluorescent probes and detected by epifluorescence microscopy and flow cytometry. The best discrimination ability was obtained with the fluorescent probes LIVE/DEAD and SYBR Green, based on the staining of cellular nucleic acid, and ChemChrome V3, which demonstrated cellular enzymatic activity. The process samples had to be diluted and filtered before fluorescence staining and analysis because they were viscous and contained solid particles. Fluorescence microscopic counts of bacteria in highly contaminated process samples were similar to plate counts, but flow cytometric enumeration of bacterial cells in process samples yielded 2- to 10-fold lower counts compared with plate counts, depending on the consistency of the sample. The detection limits in flow cytometric analysis and in epifluorescence microscopy were 103–106 cells ml−1 and 105–106 cells ml−1, respectively. Intrinsic bacterial contamination was detectable with fluorescence techniques and highly contaminated process samples could be analysed with fluorescence methods.
    Original languageEnglish
    Pages (from-to)239-244
    Number of pages6
    JournalJournal of industrial microbiology and biotechnology
    Issue number4
    Publication statusPublished - 2003
    MoE publication typeA1 Journal article-refereed


    • Starch
    • Fluorescence techniques
    • Paper industry
    • Hygiene


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