Thursday, February 28, 2008

Assaying microbial activities in paper machine processes.

To evaluate the potential of microbial growth in paper industry processes, traditional colony count analyses do not fulfil all needs.

Colony count analyses (cfu/ml or cfu/g) are well-known methods to detect certain microbes or microbial groups. The are valuable when specified troublemakers shall be detected.

Total effects of microbial growth cannot be seen by using only cfu methods because
* they do not show the activities of microbes, only their counts
* they are performed in artificial environment (nutrient media), not in the original samples

Rapid incubation of process samples is needed to show potential hazard, caused by process population. Biocide testing is also better to do in original samples from beginning to the end.

The most promising method to perform these kind of "mini-fermentations" today is PMEU incubation (Portable Microbiological Enrichment Unit; FINNOFLAG Oy; Kuopio, FINLAND) which gives results of microbial activities and effects of biocides in hours (compared with days when cfu methods are applied). No protecting, stimulating, inhibiting or other selecting effects of nutrient media are also totally excluded in process sample incubations.

One of the main ideas of microbiology is: Both the counts and activities of microbes shall be taken into account. Populations with relatively high colony counts can have slow metabolic activity - and in opposite.

As a summary: microbial activity, not the count of colonies, causes problems in paper industry processes.

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