A reverse transcriptase PCR technique for the detection and viability assessment of Kluyveromyces marxianus in yoghurt.

A fast and sensitive reverse transcriptase PCR (RT-PCR) method was developed for the detection of viable Kluyveromyces marxianus in yoghurt. Yeast-specific primers were used with the RT-PCR to evaluate the suitability of 18S rRNA as a target for the detection of viable yeasts in pure culture and yoghurt. The RT-PCR assay was able to detect down to 10(2) CFU ml(-1) in yoghurt samples contaminated with viable yeast cells. Application of the RT-PCR method to commercial yoghurt samples demonstrated the utility of this technique for detection of low concentrations of viable yeast cells in naturally contaminated dairy products. The 18S rRNA molecule is an appropriate target for cell viability assessment because of its limited persistence after cell death and the resultant high level of sensitivity of the assay.