Structures of the O-specific Polysaccharide Chains of Pectinatus cerevisiiphilus and Pectinatus frisingensis Lipopolysaccharides

Pectinatus spp. - Unpleasant and recurrent brewing spoilage bacteria

Traditionally, beer has been recognised as a beverage with high microbiological stability because of the hostile growth environment posed by beer and increasing attention being paid to brewery hygiene. However, the microbiological risk has increased in recent years because of technological advances toward reducing oxygen in beers, besides the increase in novel beer styles production, such as non-pasteurised, flash pasteurised, cold sterilised, mid-strength, and alcoholic-free beer, that are more prone to spoilage bacteria. Moreover, using innovative beer ingredients like fruits and vegetables is an added cause of microbial spoilage. To maintain quality and good brand image, beer spoilage microorganisms are a critical concern for breweries worldwide. Pectinatus and Megasphaera are Gram-negative bacteria mostly found in improper brewing environments, leading to consumer complaints and financial losses. Because of the lack of compiled scientific knowledge on Pectinatus spoilage ability, this review provides a comprehensive overview of the occurrence, survival mechanisms, and the factors affecting beer spoilage Pectinatus species in the brewing process.

Antibacterial activity of a disaccharide isolated from Streptomyces sp. strain JJ45 against Xanthomonas sp

Of the 316 actinomycetes strains isolated from various habitats, Streptomyces sp. strain JJ45 showed the strongest antibiotic activity against the plant pathogenic bacteria Xanthomonas campestris pv. campestris and was thus chosen for further study. The 16S rRNA gene sequence (1500 bp) and rpoB gene partial sequence (306 bp) of Streptomyces strains JJ45A and JJ45B were determined. The respective strain JJ45B sequences exhibited 96.8% identity with the Streptococcus gelaticus 16S rRNA gene sequence and 98.4% identity with the Streptococcus vinaceus ATCC 27478 rpoB partial sequence. The fermentation broth of the JJ45B strain was extracted to find an inhibitor of bacterial growth. The distilled water extract showed the highest activity against pathogenic bacteria. The active molecule was isolated by column chromatography on polyacrylamide or silica gel, thin-layer chromatography, and HPLC. It showed growth inhibition activity only toward phytopathogenic Xanthomonas sp. The structure of the compound was identified as alpha-l-sorbofuranose (3-->2)-beta-D-altrofuranose based on the interpretation of the nuclear magnetic resonance spectra.

The flagellin gene and protein from the brewing spoilage bacteria Pectinatus cerevisiiphilus and Pectinatus frisingensis

Flagellin genes from the anaerobic Gram-negative beer-spoilage bacteria Pectinatus cerevisiiphilus and Pectinatus frisingensis were sequenced and the flagellin proteins initially characterized. Protein microsequencing led to the design of two degenerate PCR primers that allowed the P. cerevisiiphilus flagellin gene to be partially sequenced. A combination of PCR and Bubble PCR was then used to sequence the flagellin genes of three isolates from each species. Cloning and gene expression, followed by immunoblotting, confirmed the gene identities as flagellin. Analysis of the gene sequences revealed proteins similar to other bacterial flagellins, including lengths of 446 or 448 amino acids, putative sigma 28 promoters, and a termination loop. Antibody binding studies with isolated flagella correlated with gene sequence comparisons, with both indicating that the P. cerevisiiphilus isolates studied are very similar but that the P. frisingensis isolates show greater variation. Purified flagellins were found to be glycosylated, probably through an O linkage. Phylogenetic analysis revealed greater diversity within the flagellin sequences than within the 16S rRNA genes. Despite the Gram-negative morphology of Pectinatus, this genus proved most closely related to Gram-positive Firmicutes.Key words: beer spoilage, Firmicutes, flagellin, glycosylation, Pectinatus cerevisiiphilus, Pectinatus frisingensis, phylogenetics, taxonomy.

Lipopolysaccharides of anaerobic beer spoilage bacteria of the genusPectinatus– 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.

Structure of the exceptionally large nonrepetitive carbohydrate backbone of the lipopolysaccharide of Pectinatus frisingensis strain VTT E-82164

The structures of the oligosaccharides obtained after acetic acid hydrolysis and alkaline deacylation of the rough-type lipopolysaccharide (LPS) from Pectinatus frisingensis strain VTT E-82164 were analysed using NMR spectroscopy, MS and chemical methods. The LPS contains two major structural variants, differing by a decasaccharide fragment, and some minor variants lacking the terminal glucose residue. The largest structure of the carbohydrate backbone of the LPS that could be deduced from experimental results consists of 25 monosaccharides (including the previously found Ara4NP residue in lipid A) arranged in a well-defined nonrepetitive structure: We presume that the shorter variant with R1 = H represents the core-lipid A part of the LPS, and the additional fragment is present instead of the O-specific polysaccharide. Structures of this type have not been previously described. Analysis of the deacylation products obtained from the LPS of the smooth strain, VTT E-79100T, showed that it contains a very similar core but with one different glycosidic linkage.

Impact of thermal variations on biochemical and physiological traits in Pectinatus sp

The influence of temperature on cellular fatty acid composition and on heat stress tolerance was studied in the two species of Pectinatus, an anaerobic gram-negative bacterium. Cellular fatty acid (FA) patterns were determined for Pectinatus species cultivated in MRS medium at various defined conditions of temperature and pH. Our study shows that fluctuations of growth temperature and pH induced important changes in the ratio of unsaturated FAs (UFAs) to saturated FAs (SFAs). The major differences in the FA composition as a function of growth temperature concerned C15:0 and C17:0 for the SFAs and C15:1 and C17:1 for the UFAs. The most significant adaptation of lipid composition to lower growth temperatures was the strong increase of UFAs, particularly for C15:1 and C17:1 concomitantly with a decrease of SFAs (C15:0 and C17:0). When the pH of the culture medium was lowered from 6.2 to 4.0, a notable drop in the synthesis of the UFAs C15:1 and C17:1 was observed together with an important increase of C18-cyclopropane (C18-cyc) and high carbon number SFAs. Thermal modifications also provoked changes in Pectinatus behaviour. We observed that P. cerevisiiphilus was more heat sensitive than P. frisingensis. Mild exponential phase cells were treated for 1 h, at 40 degrees C for P. cerevisiiphilus or at 41 degrees C for P. frisingensis. This thermal adaptation induced tolerance against heat challenge (49 and 50 degrees C for P. cerevisiiphilus and P. frisingensis, respectively). Survival of P. cerevisiiphilus and P. frisingensis adapted cells was, respectively, 3400- and 790-fold higher than control. Interestingly, adapted cells of P. cerevisiiphilus were more thermotolerant than P. frisingensis pretreated cells.

Chemical structure of a polysaccharide from Campylobacter jejuni 176.83 (serotype O:41) containing only furanose sugars

A neutral polysaccharide was obtained by hot phenol-water extraction of biomass from Campylobacter jejuni 176.83 and subsequently separated from acid-liberated core oligosaccharide of lipopolysaccharide by sequential GPC on Bio-Gel P6 and TSK-40 columns. All sugar components of the trisaccharide repeating unit of the polysaccharide were found to be of the furanose ring form. The major trisaccharide contained beta-L-arabinose, 6-deoxy-beta-D-altro-heptose (beta-D-6d-altHep) and 6-deoxy-beta-L-altrose (beta-L-6d-Alt), whereas in the minor trisaccharide the beta-L-6d-Alt is replaced by its C-5 epimer alpha-D-Fuc. On the basis of 1H and 13C NMR spectroscopic studies, including 2D ROESY, HMQC and HMQC-TOCSY experiments, the following structures of the repeating units were established: [formula: see text]

Structure of the O-specific polysaccharide of an Aeromonas trota strain cross-reactive with Vibrio cholerae O139 Bengal

The O-specific polysaccharide of an Aeromonas trota strain was isolated by hydrolysis of the lipopolysaccharide at pH 4.5 followed by gel-permeation chromatography and found to consist of hexasaccharide repeating units containing D-galactose, L-rhamnose, 3,6-dideoxy-L-xylo-hexose (colitose, Col), 2-acetamido-2-deoxy-D-glucose and 2-acetamido-2-deoxy-D-galactose in the ratios 1:1:2:1:1. Partial hydrolysis of the polysaccharide with 48% hydrofluoric acid resulted in selective removal of colitose to give a modified polysaccharide containing the other four sugar constituents. On the basis of methylation analysis and NMR spectroscopic studies of the initial and modified, colitose-free polysaccharide, it was concluded that the repeating unit of the O-specific polysaccharide has the following structure [sequence: see text] The known cross-reactivity between the strain studied and Vibrio cholerae O139 Bengal is substantiated by the presence of a common colitose-containing epitope shared by the O-specific polysaccharide of A. trota and the capsular polysaccharide of V. cholerae, which is thought to carry determinants of O-specificity.