Browsing by Author "Oikkonen, Hanna"

The use of recycled fibers in paper production has increased during recent years. Recycled fibers are a more sustainable alternative compared to virgin fibers made from wood. However, paper mills utilizing recycled fibers have more microbiological problems compared to mills using only virgin fibers. Especially, anaerobic bacteria are harmful for papermaking processes utilizing recycled fibers. Bacteria of the class Clostridia comprise a very diverse group and have many different metabolic properties. Bacteria of class Clostridia can ferment different substrates, for example cellulose and starch, crucial in paper mills utilizing recycled fibers. Fermentation does not only decrease material efficiency, but also the acids produced during fermentation deteriorate papermaking processes. Volatile fatty acids are odorous compounds causing bad odors in the mills and in the final products. Clostridia can also produce, for example, hydrogen which is an explosive gas endangering the safety of the mill employees. Quantitative PCR is a feasible detection method for microbes. Here, a qPCR method was developed for the detection of most abundant bacteria in the class Clostridia in the recycled fiber mills. The designed primers targeted the most harmful bacteria from the genera Clostridium, Ethanoligenens, Fonticella and Ruminococcus identified in the recycled fiber mills. Three primer sets were designed for the target bacterial group. Positive controls of each target bacterial genus was included and close relatives from class Bacilli were used as negative controls. The designed primer sets were compared in efficiency, specificity and performance with process samples collected from paper mills using recycled fibers. One of the primer sets was found the most potential for the qPCR detection method for the diverse target bacterial group. All positive controls were amplified with the designed qPCR assay, whereas the designed primers discriminated well each negative control in vitro. The applicability of the designed qPCR assay was yet confirmed with process samples collected from mills utilizing recycled pulp. Even though the efficiency of the designed primer set was not optimal, the designed assay was determined feasible for the detection of the target group in the recycled fiber mills usually high in bacterial density.