Methods for eliminationg bacterial infections in lignocellulosic material

Licentiate thesis, 2011

Bacterial infection is a major problem in industrial fermentations and may cause tremendous losses in ethanol yield if not dealt with properly. Lignocellulose is an inhibitory fermentation media which may impose increased stress on the fermenting organism, Saccahromyces cerevisiae, often leading to a decreased cell viability and fermentation performance deteriorating. This makes elimination and control of bacterial infections troublesome. Within this project two methods for controlling bacterial infections in lignocellulosic fermentations were investigated. It was investigated how different cultivation conditions for the pitching agent influence the ability of the culture to survive and boost the ethanol production capacity in an SSL-based fermentation process. It was confirmed that the cultivation conditions play an immense role for the performance of the pitching agent. Investigations on antimicrobial agents were also performed and focused on sodium chloride and ethanol. It was found that a combination of these decreased bacterial growth wile yeast viability was maintained.