The poster describes key results of the method validation for the analysis of four different packaging board grades from two board mills.
Bacteria were separated from the fibre based material before DNA extraction. Differentiation between viable and dead bacterial cells was based on a Propidium monoazide (PMA) treatment. DNA was extracted by an in-house method (enzymatic, chemical and mechanical disruption of cells and isopropanol precipitation of DNA) prior to determination of viable bacteria with quantitative polymerase chain reaction (qPCR).
Assay for total bacteria and specific assays for two relevant contaminating bacterial clusters, class Bacilli and genus-level Bacillus D cluster, were developed. Additionally, the method was proven to validly detect a broader range of bacterial clusters present in board processes.
Validation was successful for multiple operators with good statistical characteristics (linearity, accuracy and precision). The viable qPCR method can be used for determination of bacterial levels in packaging boards. Later end product measurements already provided support for data and conclusions of the validation report. In the future, accumulation of authentic end product data from packaging board process will further strengthen validity of the approach.