Modified Multiplex PCR Methods for Comprehensive Detection of Pectinatus and Beer-Spoilage Cocci

Specific PCR primers were designed based on the 16S rRNA genes of recently proposed beer-spoilage species, Pectinatus haikarae, Megasphaera sueciensis, and M. paucivorans, and two sets of our previously reported multiplex PCR methods for Pectinatus spp. and beer-spoilage cocci were reconstructed. Each modified multiplex PCR method was found specifically to detect beer-spoilage species of Pectinatus and cocci, including new species.     

Metabolic pathway to propionate of Pectinatus frisingensis,a strictly anaerobic beer-spoilage bacterium

      Pectinatus frisingensis, a recently described species of anaerobic mesophilic beer-spoilage bacteria, grows by fermenting various organic compounds, and produces mainly propionate, acetate, and succinate. Although acrylate and succinate were both dismutated by dense resting-cell suspensions, propionate production proceeded through the succinate pathway: [3-¹³C]pyruvate consumption led to equal ¹³C-labeling of propionate on methyl and methylene groups. Growth on glucose or glycerol led to a similar propionate to acetate ratio, suggesting dihydroxyacetone phosphate as being a common metabolic intermediate. Diacetyl, 1,3-propanediol, and 2,3-butanediol were not growth substrates or fermentation products, but they were all dismutated by dense resting-cell suspensions to acetate and propionate. Acetoin was a minor fermentation product. The consumption of [2-¹³C] or [3-¹³C]pyruvate by dense resting-cell suspensions demonstrated the involvement of two equivalent pyruvate molecules during acetoin production. Key enzymes involved in this metabolism were measured in anoxic cell-free extracts. A tentative metabolic pathway to the main fermentation products was proposed from the above results. Received: 17 February 1994 / Accepted: 30 August 1994     

Lipopolysaccharides of anaerobic beer spoilage bacteria of the genus Pectinatus--lipopolysaccharides of a Gram-positive genus

Bacteria of the genus Pectinatus emerged during the seventies as contaminants and spoilage organisms in packaged beer. This genus comprises two species, Pectinatus cerevisiiphilus and Pectinatus frisingensis; both are strict anaerobes. On the basis of genomic properties the genus is placed among low GC Gram-positive bacteria (phylum Firmicutes, class Clostridia, order Clostridiales, family Acidaminococcaceae). Despite this assignment, Pectinatus bacteria possess an outer membrane and lipopolysaccharide (LPS) typical of Gram-negative bacteria. The present review compiles the structural and compositional studies performed on Pectinatus LPS. These lipopolysaccharides exhibit extensive heterogeneity, i.e. several macromolecularly and structurally distinct LPS molecules are produced by each strain. Whereas heterogeneity is a common property in lipopolysaccharides, Pectinatus LPS have been shown to contain exceptional carbohydrate structures, consisting of a fairly conserved core region that carries a large non-repetitive saccharide that probably replaces the O-specific chain. Such structures represent a novel architectural principle of the LPS molecule.