Pectinatus, a New Genus of the Family Bacteroidaceae

Abstract

The properties of an anaerobic, rod-shaped bacterium having an unusual flagellar arrangement are described. The flagella emanate from only one side of the cell body and are not limited to the center portion as they are with selenomonads. The organism is a gramnegative, nonsporeforming mesophile producing acetic, propionic, and succinic acids and traces of lactic acid from glucose fermentation. The guanine-plus-cytosine content of the deoxyribonuleic acid is 39.8 mol%. The characteristics of this organism indicate that it belongs in none of the presently described genera. For this organism, we propose a new genus, Pectinatus, and a new species, Pectinatus cerevisiiphilus, in the family Bacteroidaceae. The type strain, CCC B-1022, has been deposited in the American Type Culture Collection under the number 29359.Few organisms are capable of growing in normal packaged beers because of the inherent selectivity brought about by pH, alcohol content, hop residuals, and the lack of oxygen. The organisms generally referred to as "beer spoilage bacteria" are classified in the following genera: Acetobacter, Acetomonas, Lactobacillus, Pediococcus, and Zymomonas. Other bacteria, such as enterobacters and flavobacteria, are considered to be problems in the early brewing process but never in the final packaged product (1). During the course of routine identification work on bacteria in our brewery, we isolated an unusual bacterium capable of growing in beer. Unlike other common organisms, this organism was a strict anaerobe, producing no growth aerobically on solid media. Under anaerobic conditions it fermented several sugars. Scanning electron microscopy (SEM) revealed that flagella were attached on only one side of the cell body, giving the cells the appearance of hair combs. The unique features of this organism clearly indicated that it was not a "typical" beer bacterium, and to our knowledge an organism of this type has not, to date, been described in the literature. The purpose of this study was to present some of the morphological and biochemical characteristics of this new isolate and to determine its taxonomic position. MATERIALS AND METHODSBacterial strain. Only one strain (CCC B-1022) was studied. It was isolated from beer which had been stored at 30°C for 30 days. Stock cultures were maintained by biweekly transfers in freshly prepared MRS lactobacilli broth (Difco) with minimal head space in the tube and with incubation at 30°C. Between transfers, cultures were stored at 2°C.Media. For sugar utilization tests and for gas chromatographic analyses of volatile and nonvolatile fatty acids, prereduced media were used as described in the VPI Anaerobe Laboratory Manual (4). Cultures were grown in MRS lactobacilli broth (Difco) for determination of deoxyribonucleic acid (DNA) base composition, for preparation of cells for SEM photography, and for thin sections for electron microscopy. Thioglycolate agar with glucose (Difco) was used to obtain growth on solid media in Hungate roll tubes (5).Biochemical tests. Peptone yeast e...

Enhancing the Microbiological Stability of Malt and Beer - A Review

“…Pectinatus cerevisiiphilus was first described by Lee et al 109 Currently, Pectinatus species have been implicated in 20-30% of bacterial spoilage incidents encountered in finished product, usually in non-pasteurised rather than pasteurised beers 5 . The natural habitats and sources of the Pectinatus spp.…”

“…Beer spoilage by Pectinatus spp. is characterised by extensive turbidity and an offensive 'rotten egg' smell as a result of the production of hydrogen sulphide and methyl mercaptan 72,109,110 .…”

Thermosinus carboxydivorans gen. nov., sp. nov., a new anaerobic, thermophilic, carbon-monoxide-oxidizing, hydrogenogenic bacterium from a hot pool of Yellowstone National Park

“…Strain Nor1 T differs from Thermanaerovibrio species by the ability to grow chemolithotrophically on CO, producing H 2 and CO 2 , and the phylogenetic distance between Nor1 T strain and Thermanaerovibrio species. A phylogenetic analysis revealed that strain Nor1 T adds to the list of bacterial genera that show Gram-negative-type cell walls but belong to the phylogenetic lineage of Gram-positive bacteria (Lee et al, 1978). By similarity percentage, the closest relative appears to be D. quercicolus (Strömpl et al, 2000).…”

Occurrence of Pectinatus and Megasphaera in the Major UK Breweries

“…Pectinatus was reported as a new genus of Gram negative, catalase negative, motile, obligate beer spoilage bacteria in the 1970s, when it was first isolated from a brewery in the United States in unpasteurized beer stored at 30°C 31 . P. cerevisiiphilus was later isolated from breweries in Finland, Germany, Norway, Japan, Spain, Netherlands, Sweden and France 15,29,45,50 .…”

“…In recent studies, a third species, Pectinatus haikarae was identified on the basis of 16S rRNA gene sequence analysis and differences in sugar utilization, catalase activity, antibiotic resistance and temperature tolerance compared to the two previously characterised 25 . The growth of Pectinatus species is accompanied by extensive turbidity and an offensive aroma similar to rotten egg due to the production of various fatty acids, hydrogen sulphide and methyl mercaptan 15,31 .…”