Evaluation of propidium monoazide (PMA) treatment directly on membrane filter for the enumeration of viable but non cultivable Legionella by qPCR.

A PMA (propidium monoazide) pretreatment protocol, in which PMA is applied directly to membrane filters, was developed for the PCR-based quantification (PMA-qPCR) of viable Legionella pneumophila. Using this method, the amplification of DNA from membrane-damaged L. pneumophila was strongly inhibited for samples containing a small number of dead bacteria.

Sensitive counting of viable Enterobacteriaceae in seawaters and relationship with fecal indicators.

A fluorescent in situ hybridization based assay was used to enumerate viable Enterobacteriaceae members in seawaters by solid phase cytometry. The method was specific, highly sensitive (1cell/100ml) and allowed the quantification of VNC Enterobacteriaceae cells during an osmotic stress. Investigations on contaminated coastal seawater revealed a strong correlation between Enterobacteriaceae counts and standard fecal indicators.