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International Journal of Systematic and... Jul 2003Eleven psychrophilic bacteria isolated from Antarctic coastal marine environments were subjected to a polyphasic taxonomic study. The isolates were oxidase-positive,...
Eleven psychrophilic bacteria isolated from Antarctic coastal marine environments were subjected to a polyphasic taxonomic study. The isolates were oxidase-positive, halotolerant, gram-negative, non-motile coccobacilli with a strictly oxidative metabolism. The DNA G + C content ranged from 44 to 47 mol%. DNA-DNA hybridization experiments showed six homology groups, two of them related at the species level to the type strain of Psychrobacter immobilis, LMG 7203T (70-83%). The highest DNA relatedness of two other groups to known Psychrobacter species was found to the type strain of Psychrobacter glacincola, LMG 21282T (51-57%), and no significant similarity was found between Psychrobacter type strains and the last two groups. The predominant cellular fatty acids detected were typical of the genus Psychrobacter and included 18:1omega9c, 16:1omega7c and 17:1omega8c. 16S rRNA gene sequence analysis confirmed that the strains isolated belonged to the genus Psychrobacter. The results of the study assigned five isolates to P. immobilis, three isolates to P. glacincola and three isolates to novel Psychrobacter species. The names Psychrobacter luti sp. nov. (type strain NF11T=LMG 21276T=CECT 5885T) and Psychrobacter fozii sp. nov. (type strain NF23T=LMG 21280T=CECT 5889T) are proposed for these organisms.
Topics: Antarctic Regions; Base Composition; DNA, Bacterial; DNA, Ribosomal; Fatty Acids; Gammaproteobacteria; Microscopy, Electron; Molecular Sequence Data; Phenotype; Phylogeny; RNA, Bacterial; RNA, Ribosomal, 16S
PubMed: 12892132
DOI: 10.1099/ijs.0.02457-0 -
International Journal of Food... Jul 2003Salt-cured and dried salt-cured cod rehydrated using sterile water and equipment have a short shelf life at 4 degrees C due to high bacterial counts. The microbiota...
Salt-cured and dried salt-cured cod rehydrated using sterile water and equipment have a short shelf life at 4 degrees C due to high bacterial counts. The microbiota develops off-odours which partly can be described as musty, causing sensory rejection within 7-10 days of chilled storage. The microbiota composition was studied in a total of 38 samples obtained from 10 different, both commercial and laboratory produced, salt-cured and dried salt-cured cod products. The dominating bacterium, representing at least 90% of the total viable count in all products studied, was identified as belonging to the genus Psychrobacter; a Gram-negative, oxidase- and catalase-positive, nonpigmented, halotolerant, psychrotolerant, facultative aerobe and nonmotile bacterium. The morphology of the bacterium resembles coccobacilli and the cells occur most often in pairs. The bacterium was able to hydrolyze lipids, but not proteins. It did not produce H(2)S or TMA and the spoilage in rehydrated salt-cured and dried salt-cured cod is therefor different from what is observed in fresh cod. However, samples inoculated with Psychrobacter immobilis gave the same musty odour as spoiled control samples but earlier in the storage period and of a stronger intensity. In a field experiment, carried out to investigate the origin of the dominating bacterium, it was found that the microbiota in both sterile rehydrated commercially produced and laboratory (aseptically) produced salt-cured cod was dominated by this same bacterium. The bacterium was also isolated from cod skin mucus immediately after capture. The bacterium survived NaCl concentrations up to 25% (w/v) NaCl, stating its ability to survive during the salt-curing process. The dominating bacterium in rehydrated salt-cured and dried salt-cured cod seems to mainly originate from the fresh fish itself and not from contamination during processing.
Topics: Animals; Colony Count, Microbial; Fishes; Food Contamination; Food Handling; Food Microbiology; Food Preservation; Gram-Negative Facultatively Anaerobic Rods; Odorants; Temperature; Time Factors
PubMed: 12781940
DOI: 10.1016/s0168-1605(02)00418-x -
International Journal of Systematic and... Mar 2003Unusual Gram-negative, catalase- and oxidase-positive, coccus-shaped bacteria isolated from the lungs of two lambs were characterized by phenotypic and molecular-genetic...
Unusual Gram-negative, catalase- and oxidase-positive, coccus-shaped bacteria isolated from the lungs of two lambs were characterized by phenotypic and molecular-genetic methods. Comparative 16S rRNA gene sequencing studies demonstrated that the unknown isolates were genealogically highly related to each other (99.8% sequence similarity) and represent a novel subline within the genus Psychrobacter. The unknown bacterium was phylogenetically closely related to, but distinct from, Psychrobacter phenylpyruvicus, Psychrobacter immobilis, Psychrobacter glacincola and Psychrobacter urativorans. The novel Psychrobacter isolates were readily distinguished from all other Psychrobacter species and other Gram-negative, oxidase-positive bacteria usually responsible for lung infections in sheep by physiological and biochemical tests. Based on molecular-genetic and phenotypic evidence, it is proposed that the unknown Psychrobacter isolates from lambs be classified as Psychrobacter pulmonis sp. nov. The type strain is strain S-606T (=CECT 5989T =CCUG 46240T).
Topics: Animals; Gammaproteobacteria; Gram-Negative Bacterial Infections; Lung; Molecular Sequence Data; Phylogeny; RNA, Ribosomal, 16S; Sequence Analysis, DNA; Sheep; Sheep Diseases
PubMed: 12710606
DOI: 10.1099/ijs.0.02413-0 -
Journal of Clinical Microbiology Mar 2003CDC eugonic oxidizer group 2 (EO-2) is a group of unclassified gram-negative bacterial strains isolated from various human sources. As determined by biochemical tests...
CDC eugonic oxidizer group 2 (EO-2) is a group of unclassified gram-negative bacterial strains isolated from various human sources. As determined by biochemical tests and analyses of fatty acid compositions, these organisms form a homogeneous group that appears to be distinct from but related to other Paracoccus species. Molecular studies were performed on a set of 13 EO-2 strains from various clinical sources and geographic locations in the United States and Canada to determine their relationship to the Paracoccus genus. Control strains were Paracoccus denitrificans ATCC 17741(T), P. versutus ATCC 25364(T), P. aminophilus ATCC 49673(T), P. solventivorans ATCC 700252(T), and Psychrobacter immobilis ATCC 43116(T), which are phenotypically similar to EO-2. Nearly complete (1,500-base) 16S rRNA gene sequencing of eight EO-2 strains showed a high level of sequence similarity (>99.3%) within the group, and a BLAST search of GenBank placed the EO-2 cluster in close proximity to Paracoccus species (95 to 97% similarity). DNA-DNA hybridization studies of 13 of the EO-2 strains showed all to be related at the species level, with >70% relatedness under stringent conditions and a divergence within the group of less than 2%. None of the Paracoccus control strains hybridized at >54% with any of the EO-2 strains. These results indicate that EO-2 represents a new Paracoccus species, the first isolated from human clinical specimens. A new species, Paracoccus yeeii, is proposed for the EO-2 strains. The type strain of P. yeeii is CDCG1212 (ATCC BAA-599 and CCUG 46822), isolated in Pennsylvania from dialysate of a 77-year-old male with peritonitis.
Topics: DNA, Bacterial; Gram-Negative Bacterial Infections; Humans; Molecular Sequence Data; Paracoccus; Phenotype; Phylogeny; RNA, Ribosomal, 16S
PubMed: 12624070
DOI: 10.1128/JCM.41.3.1289-1294.2003 -
Systematic and Applied Microbiology Apr 2001An Antarctic marine bacterium (strain 116) excreting an extracellular cold-adapted metalloprotease was subjected to a detailed polyphasic taxonomic investigation. Strain...
Psychrobacter proteolyticus sp. nov., a psychrotrophic, halotolerant bacterium isolated from the Antarctic krill Euphausia superba Dana, excreting a cold-adapted metalloprotease.
An Antarctic marine bacterium (strain 116) excreting an extracellular cold-adapted metalloprotease was subjected to a detailed polyphasic taxonomic investigation. Strain 116 was previously isolated from the stomach of a specimen of the Antarctic krill Euphasia superba Dana and tentatively characterized as Sphingomonas paucimobilis 116. The 16S rDNA sequence analysis showed that the strain is in fact related to species of the genus Psychrobacter, next to Psychrobacter glacincola (97.4% similarity). Sequence similarities between strain 116 and other Psychrobacter species ranged from 96.9% (with P. urativorans) to 95.4% (with P. immobilis). Key phenotypic characteristics as well as chemotaxonomic features of the bacterium were congruent with the description of the genus Psychrobacter i.e. cells were strictly aerobic, strongly oxidase-positive, psychrotrophic, halotolerant, gram-negative non-motile coccobacilli, with ubiquinone-8 as the main respiratory lipoquinone and 18:1 cis 9, 16:1 cis and 17:1 (omega8c being the predominant cellular fatty acids. The G+C content of the DNA was 43.6 mol%. DNA-DNA hybridization studies showed that the relatedness between strain 116 and Psychrobacter glacinola is only 62.2%. Further differences were apparent in whole-cell SDS-PAGE protein pattern, cellular fatty acid profile and in a number of physiological and biochemical characteristics as well as in enzymatic activities. Tolerance to 5% bile salts, nitrate reduction, citrate utilization, acid production from carbohydrates, alkaline phosphatase, acid phosphatase, C4 esterase, C14 lipase and valine arylamidase were found to differentiate strain 116 from Psychrobacter glacincola. On the basis of this phenotypic and molecular evidences, strain 116, previously known as Sphingomonas paucimobilis 116, was recognized as a new species of the genus Psychrobacter for which the name Psychrobacter proteolyticus is proposed. Strain 116 has been deposited in the Collection de l'Institut Pasteur, France, as CIP106830T and in the Deutsche Sammlung von Mikroorganismen and Zellkulturen, as DSM13887.
Topics: Adaptation, Biological; Animals; Antarctic Regions; Bacterial Proteins; Bacterial Typing Techniques; Cold Temperature; Crustacea; DNA, Ribosomal; Drug Resistance, Microbial; Fatty Acids; Gammaproteobacteria; Gram-Negative Aerobic Rods and Cocci; Metalloendopeptidases; Molecular Sequence Data; RNA, Ribosomal, 16S; Salts
PubMed: 11403398
DOI: 10.1078/0723-2020-00006 -
Microbios 2000A new lysis solution designated TZ, consisting of 2.0% Triton X-100 plus 2.5 mg sodium azide/ml in 0.1 M Tris-HCl buffer at pH 8.0, yielded higher levels of genomic DNA...
A new lysis solution designated TZ, consisting of 2.0% Triton X-100 plus 2.5 mg sodium azide/ml in 0.1 M Tris-HCl buffer at pH 8.0, yielded higher levels of genomic DNA from Escherichia coli O157:H7 cells compared with a number of other commonly used cell lysis methods. Ethidium bromide stained DNA bands resulting from PCR amplification of target DNA from 100 CFU of E. coli O157:H7 were readily detected following electrophoresis of agarose gels. In contrast, conventional cell lysis methods failed to detect target DNA from 100 CFU after PCR amplification. The new solution was highly effective for lysing cell suspensions of Salmonella enteritidis, Pseudomonas putida, Lysteria monocytogenes and Psychrobacter immobilis.
Topics: Buffers; DNA, Bacterial; Escherichia coli O157; Fluorometry; Image Processing, Computer-Assisted; Indicators and Reagents; Listeria monocytogenes; Polymerase Chain Reaction; Pseudomonas putida; Salmonella enteritidis; Sodium Azide
PubMed: 10756522
DOI: No ID Found -
Journal of Food Protection Mar 2000Three phenotypic identification systems were employed to identify 106 strains of gram-negative, nonmotile, aerobic bacteria obtained during iced storage of wild (Salmo...
Three phenotypic identification systems were employed to identify 106 strains of gram-negative, nonmotile, aerobic bacteria obtained during iced storage of wild (Salmo trutta and Esox lucius) and farmed (Oncorhynchus mykiss) freshwater fish. Using diagnostic tables and computer-assisted identification, the isolates were Psychrobacter (64 strains), Acinetobacter (24 strains), Moraxella (6 strains), Chryseobacterium (5 strains), Myroides odoratus (2 strains), Flavobacterium (1 strain), Empedobacter (1 strain), and unidentified (3 strains). Overall similarities of all strains were determined for 108 characters by numerical analysis (simple matching coefficient of similarity [S] and clustering by unweighted pair group average linkage [UPGMA]). At the 77% similarity level, 92 strains formed nine major clusters (3 or more strains) and four small clusters (2 strains). Cluster 1 (25 isolates divided into two main subclusters) could be assigned to Psychrobacter phenylpyruvicus, clusters 2 and 3 (26 isolates) were designated as Psychrobacter immobilis, and clusters 4 (3 isolates) and 7 (4 isolates) were identified as Psychrobacter urativorans and Psychrobacter spp., respectively. Clusters 5 (five isolates), 6 (three isolates), and 9 (five isolates) were labeled as Acinetobacter spp., Acinetobacter johnsonii, and Acinetobacter lwoffii, respectively. Cluster 8 (12 isolates), with a high resemblance to Thornley's phenon 4 (a heterogeneous group of bacteria isolated from poultry and related to Acinetobacter), remained unnamed. The restriction pattern was identical for strains grouped into clusters 2 and 3 (P. immobilis) but was different for the remaining Psychrobacter isolates. A large proportion of isolates belonging to the family Moraxellaceae were closely related. Psychrobacters and A. johnsonii were present in freshly caught fish and river water. In the latter stages of storage, P. phenylpyruvicus and acinetobacters tended to decrease, whereas P. immobilis increased.
Topics: Animals; Bacterial Typing Techniques; Cold Temperature; DNA, Ribosomal; Esocidae; Fishes; Food Handling; Fresh Water; Gram-Negative Aerobic Bacteria; Numerical Analysis, Computer-Assisted; Oncorhynchus mykiss; Phenotype; RNA, Ribosomal, 16S; Restriction Mapping; Trout
PubMed: 10716558
DOI: 10.4315/0362-028x-63.3.315 -
Comparative Biochemistry and... Nov 1997Two novel phenylalanine-rich antimicrobial peptides, Styelin A and Styelin B, were purified from the hemocytes of Styela clava. The peptides had very similar masses...
Two novel phenylalanine-rich antimicrobial peptides, Styelin A and Styelin B, were purified from the hemocytes of Styela clava. The peptides had very similar masses (Styelin A, 3685.8; Styelin B, 3700.6) and amino acid compositions, and at least 17 of their first 20 N-terminal residues were identical. Both Styelins were effective against a panel of gram negative and gram positive bacterial pathogens of humans, usually acting with minimal inhibitory concentrations < 1.5 microgram/ml (< 0.5 microM), even in the presence of 100 mM NaCl. Styelins also killed marine bacteria, Psychrobacter immobilis and Planococcus citreus, in media containing 0.4 M NaCl. The presence of antimicrobial peptides (Styelins) in tunicate hemocytes is evidence that such molecules are ancient mediators of host defense within the vertebrate lineage. Peptide antibiotics from marine organisms could afford design template for the development of topical microbicides that manifest broad-spectrum antibacterial activity in the presence of physiological or elevated NaCl concentrations.
Topics: Amino Acids; Animals; Anti-Bacterial Agents; Drug Evaluation, Preclinical; Gram-Negative Aerobic Bacteria; Gram-Positive Bacteria; Hemocytes; Hydrogen-Ion Concentration; Microbial Sensitivity Tests; Peptides; Proteins; Urochordata
PubMed: 9467865
DOI: 10.1016/s0305-0491(97)00109-0 -
European Journal of Biochemistry Feb 1997A heat-labile beta-lactamase has been purified from culture supernatants of Psychrobacter immobilis A5 grown at 4 degrees C and the corresponding chromosomal ampC gene...
A heat-labile beta-lactamase has been purified from culture supernatants of Psychrobacter immobilis A5 grown at 4 degrees C and the corresponding chromosomal ampC gene has been cloned and sequenced. All structural and kinetic properties clearly relate this enzyme to class C beta-lactamases. The kinetic parameters of P. immobilis beta-lactamase for the hydrolysis of some beta-lactam antibiotics are in the same range as the values recorded for the highly specialized cephalosporinases from pathogenic mesophilic bacteria. By contrast, the enzyme displays a low apparent optimum temperature of activity and a reduced thermal stability. Structural factors responsible for the latter property were analysed from the three-dimensional structure built by homology modelling. The deletion of proline residues in loops, the low number of arginine-mediated H-bonds and aromatic-aromatic interactions, the lower global hydrophobicity and the improved solvent interactions through additional surface acidic residues appear to be the main determinants of the enzyme flexibility.
Topics: Adaptation, Physiological; Amino Acid Sequence; Antarctic Regions; Base Sequence; Chromosomes, Bacterial; Cold Temperature; Enzyme Stability; Genes, Bacterial; Gram-Negative Aerobic Bacteria; Hot Temperature; Molecular Sequence Data; beta-Lactamases
PubMed: 9063463
DOI: 10.1111/j.1432-1033.1997.00186.x -
The Biological Bulletin Dec 1996The antimicrobial defenses of anthozoans were investigated in vitro by extracting amoebocytes from the mesenteric filaments of the beadlet anemone, Actinia equina, and...
The antimicrobial defenses of anthozoans were investigated in vitro by extracting amoebocytes from the mesenteric filaments of the beadlet anemone, Actinia equina, and testing for their ability to phagocytose and kill the gram-negative bacterium Psychrobacter immobilis. Only the hyaline amoebocytes exhibited phagocytosis in vitro, with about 40% seen to ingest one or more bacteria over 45 min. Mixed cultures of viable amoebocytes were further found to produce O2- ions and other reactive oxygen species (ROS) after stimulation with phorbol myristate acetate or lipopolysaccharide. Co-incubation of viable amoebocytes with P. immobilis for 3 h in vitro resulted in reduced growth of the bacterium compared to saline-incubated bacteria, but because the growth of P. immobilis was also impaired by lysed control amoebocytes, the contribution made to bacterial killing by ROS could not be evaluated. Instead, as confirmed by additional experiments using lysate supernatants of the amoebocytes, it appears that the cells contain soluble bactericidal factors. The nature of these agents is at present unknown, although preliminary tests indicate that killing is not mediated by lysozyme.
PubMed: 29215925
DOI: 10.2307/1543017