Comparative genetic and physiological characterisation of Pectinatus species reveals shared tolerance to beer-associated stressors but halotolerance specific to pickle-associated strains

Abstract

Obligate anaerobic bacteria from the genus Pectinatus have been known to cause beer spoilage for over 40 years. Whole genome sequencing was performed on eleven beer spoilage strains (nine Pectinatus frisingensis, one Pectinatus cerevisiiphilus and one Pectinatus haikarae isolate), as well as two pickle spoilage species (Pectinatus brassicae MB591 and Pectinatus sottacetonis MB620) and the tolerance of all species to a range of environmental conditions was tested. Exploration of metabolic pathways for carbohydrates, amino acids and vitamins showed little difference between beer spoilage-and pickle spoilage-associated strains. However, genes for certain carbohydrate and sulphur-containing amino acidassociated enzymes were only present in the beer spoilage group and genes for specific transporters and regulatory genes were uniquely found in the pickle spoilage group. Transporters for compatible solutes, only present in pickle-associated strains, likely explain their experimentally observed higher halotolerance compared to the beer spoilers. Genes involved in biofilm formation and ATP Binding Cassette (ABC) transporters potentially capable of exporting hop-derived antimicrobial compounds were found in all strains. All species grew in the presence of alcohol up to 5% alcohol by volume (ABV) and hops extract up to 80 ppm of iso-α-acids. Therefore, the species isolated from pickle processes may pose novel hazards in brewing.

High rate acidogenic fermentation in an up-flow anaerobic sludge bed reactor at extremely low pH

“…Prevotella were reported to be able to grow at pH as low as 5.0-5.5 and could utilize glucose to produce organic acids such as formic acid, acetate, fumaric acid succinic acid [37]. Dialister are obligate anaerobic and nonfermentative organisms [38], While Pectinatus could degrade organic substrate to acetate, propionate and H 2 S [39]. The acidogenic granular sludge in this study was mixed-cultured and the different microorganisms were likely with different fermentative routes.…”