Strictly anaerobic bacteria in beer and in breweries.

Abstract

The content of oxygen is one of the main factors affecting microbiological stability of beer. The current trend in the development of bottling technologies therefore accentuates lowering of oxygen tension in finished beer to a minimum. Beer thus becomes a medium in which strictly anaerobic bacteria that require for their growth and proliferation very low or zero oxygen level can thrive. Strictly anaerobic bacteria capable of spoiling beer or contaminating brewer's yeast belong to the genera Pectinatus, Megasphaera, Zymophilus and Selenomonas. The increasing frequency of beer spoilage cases is also promoted by increasing production of beers that have a higher propensity to microbial spoilage - nonpasteurized, nonalcoholic, low-alcoholic and low hopped beers. A survey is presented here of basic morphological, biochemical and physiological properties of this group of bacteria.The content of oxygen is one of the main factors affecting microbiological stability of beer. The current trend in the development of bottling technologies therefore accentuates lowering of oxygen tension in finished beer to a minimum. Beer thus becomes a medium in which strictly anaerobic bacteria that require for their growth and proliferation very low or zero oxygen level can thrive. Strictly anaerobic bacteria capable of spoiling beer or contaminating brewer's yeast belong to the genera Pectinatus, Megasphaera, Zymophilus and Selenomonas. The increasing frequency of beer spoilage cases is also promoted by increasing production of beers that have a higher propensity to microbial spoilage - nonpasteurized, nonalcoholic, low-alcoholic and low hopped beers. A survey is presented here of basic morphological, biochemical and physiological properties of this group of bacteria.

Keywords

• strictly anaerobic bacteria
• Pectinatus
• Zymophilus
• Selenomonas
• Megasphaera
• beer spoilage
• yeast contamination