Improved Enrichment Cultivation of Beer Spoiling Lactic Acid Bacteria by Continuous Glucose Addition to the Culture

Sanna Taskila^1,6, Peter Neubauer^1,2, Mika Tuomola³, Antje Breitenstein⁴, Jukka Kronlöf⁵ and Tomi Hillukkala¹
¹ Bioprocess Engineering Laboratory, Department of Process and Environmental Engineering, University of Oulu, P. O. Box 43100, FI-90014 Oulu, Finland.
² Current address: Department of Biotechnology, Technische Universität Berlin, Ackerstr. 71-76, D-13355 Berlin, Germany.
³ Current address: Thermo Fisher Scientific Ltd., Ratastie 2, P. O. Box 100, FI-01621, Vantaa, Finland.
⁴ Scanbec GmbH, Weinbergweg 23, D-03120 Halle/S., Germany.
⁵ Hartwall Ltd., Kasaajankatu 13, P. O. Box 44, FI-15101 Lahti, Finland.
⁶ Corresponding author. E-mail: sanna.taskila@oulu.fi.

J. Inst. Brew. 115(3), 177–182, 2009 | VIEW ARTICLE

ABSTRACT
Lactic acid bacteria (LAB) are known as predominant beer spoilers. They cause turbidity, acidity, gas formation and offflavors in beer by formation of side metabolites. Beer spoiling LAB have a substantial financial impact in the brewing industry making their rapid detection and identification essential. Despite the developed rapid diagnostic methods, the bottleneck in detection remains the lengthy enrichment cultivation step. This paper describes the applicability of a novel glucose auto delivery system, EnBase™, for the improved enrichment cultivation of beer spoiling LAB in MRS medium. By means of the applied system, glucose is slowly released into the culture during growth, which results in faster enrichment. Growth of Lactobacillus brevis DSM 20054T and several beer spoiling LAB was accelerated resulting in up to a 300% increase in the cell density after 48 h of cultivation compared to the commonly used MRS medium. A test of naturally contaminated beer samples indicated that the addition of glucose by means of EnBase allows faster detectionof LAB in breweries.

Key words:
beer spoilage, contaminant detection, enrichment cultivation, lactic acid bacteria, Lactobacillus.