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PubMed2003

Psychrobacter okhotskensis sp. nov., a lipase-producing facultative psychrophile isolated from the coast of the Okhotsk Sea.

A facultatively psychrophilic bacterium, strain MD17(T), which hydrolyses lipids at 5 degrees C, was isolated from the Monbetsu coast of the Okhotsk Sea in Hokkaido, Japan, when ice carried by the cold current came to the area. The isolate is an aerobic, non-motile coccobacillus that reduces nitrate to nitrite and hydrolyses Tweens 20, 40, 60 and 80, but not gelatin, DNA or alginic acid. The isolate grows at 0 degrees C, but not at temperatures higher than 36 degrees C; its optimum growth temperature is 25 degrees C. It grows in the presence of 0-10 % NaCl. Its major isoprenoid quinone is ubiquinone-8 (Q-8) and its DNA G+C content is 46.7 mol%. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain MD17(T) is closely related to Psychrobacter glacincola DSM 12194(T) (99.0 % similarity) and Psychrobacter immobilis DSM 7229(T) (98.7 % similarity). DNA-DNA hybridization revealed 45.9 % relatedness between strain MD17(T) and P. immobilis ATCC 43116(T) and 33.4 % between strain MD17(T) and P. glacincola ATCC 700754(T). Based on physiological and biochemical characteristics, phylogenetic position (as determined by 16S rRNA gene sequence analysis) and DNA-DNA relatedness, it is concluded that the isolate should be designated as a novel species, for which the name Psychrobacter okhotskensis sp. nov. is proposed. The type strain is MD17(T) (=NCIMB 13931(T)=JCM 11840(T)).

Base Composition↗

PubMed1987

Relationship of CDC group EO-2 and psychrobacter immobilis.

Thirty strains of microorganisms previously classified in the CDC group EO-2 were studied to determine the relationship of this group and the recently proposed Psychrobacter immobilis. Results of transformation studies indicated that 9 of the 30 studied strains should be reclassified as P. immobilis. While transformation studies should be used to identify the Psychrobacter genus definitively, some presumptive characteristics useful in differentiating the CDC group EO-2 and P. immobilis were observed. The Psychrobacter genus, compared with the CDC group EO-2, grew well at 25 degrees C, lightly or not at all at 35 degrees C, and not at all at 42 degrees C, grew in nutrient broth without NaCl and with only one exception grew in 6% NaCl, usually did not produce acid from adonitol, dextrin, fructose, or D-mannitol, did not demonstrate the O-shaped cellular morphology, and usually possessed an odor resembling that noted from a phenylethyl alcohol blood agar plate.

DNA, Bacterial↗

PubMed2006

Surgical wound infection associated with Psychrobacter phenylpyruvicus-like organism.

A case of surgical wound infection caused by Psychrobacter phenylpyruvicus-like organism is described. The strain showed phenotypic characteristics typical of P. phenylpyruvicus, but 16S rRNA sequencing showed 98.2% relatedness to Moraxella phenylpyruvica strain 752/52 and only 94.8% with P. phenylpyruvicus type strain ATCC 23333(T). The results of molecular analysis suggest that the strain we isolated may represent a new species within the genus Psychrobacter.

Aged↗

PubMed2005

Psychrobacter bacteraemia in a cirrhotic patient after the consumption of raw geoduck clam.

Psychrobacter species rarely cause infections in human. We reported herein a 62-year-old cirrhotic patient who presented with fever and diarrhoea after the consumption of raw geoduck clam. Blood culture grew Psychrobacter phenylpyruvicus which was sensitive to most anti-microbial agents. The patient responded promptly to intravenous antibiotics. This is the first report of human infection with this unusual organism which illustrates the potential health hazards of eating raw geoduck clam in patients with advanced liver disease.

Ampicillin↗

PubMedDate not supplied

Isolation and characterization by conventional methods and genetic transformation of Psychrobacter and Acinetobacter from fresh and spoiled meat, milk and cheese.

Of 126 samples of fresh and spoiled meat and dairy products, 40% were positive for the presence of Moraxella-like bacteria and 64% of Acinetobacter; 279 and 466 strains, respectively, were isolated and a part of these were tested by biochemical methods and DNA transformation assays. In some cases, the Moraxellaceae in the samples examined reached considerable quantitative levels, but their percentage in the microflora was generally low. Moraxella-like bacteria were predominant in fresh meat, Acinetobacter in spoiled meat and milk. Most acinetobacters belonged to biotype lwoffii (sensu lato) and all 90 strains tested were positive for DNA transformation with an auxotrophic Acinetobacter. Moraxella-like bacteria were identified as Psychrobacter immobilis in 96% of 103 transformation assays. Moraxellaceae show lipolytic activity but they are considered of low incidence in food spoilage. Only 3.7% of acinetobacters from dairy sources was able to produce ropy milk. Unlike strains from clinical isolates, psychrobacters and acinetobacters isolated from food often do not grow at 37 degrees C.

Acinetobacter↗

PubMed2003

Origin and spoilage potential of the microbiota dominating genus Psychrobacter in sterile rehydrated salt-cured and dried salt-cured cod (Gadus morhua).

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.

Animals↗

PubMed2002

The Antarctic Psychrobacter sp. TAD1 has two cold-active glutamate dehydrogenases with different cofactor specificities. Characterisation of the NAD+-dependent enzyme.

Psychrobacter sp. TAD1 is a psychrotolerant bacterium from Antarctic frozen continental water that grows from 2 to 25 degrees C with optimal growth rate at 20 degrees C. The new isolate contains two glutamate dehydrogenases (GDH), differing in their cofactor specificities, subunit sizes and arrangements, and thermal properties. NADP+-dependent GDH is a hexamer of 47 kDa subunits and it is comparable to other hexameric GDHs of family-I from bacteria and lower eukaria. The NAD+-dependent enzyme, described in this communication, has a subunit weight of 160 kDa and belongs to the novel class of GDHs with large size subunits. The enzyme is a dimer; this oligomeric arrangement has not been reported previously for GDH. Both enzymes have an apparent optimum temperature for activity of approximately 20 degrees C, but their cold activities and thermal labilities are different. The NAD+-dependent enzyme is more cold active: at 10 C it retains 50% of its maximal activity, compared with 10% for the NADP+-dependent enzyme. The NADP+-dependent enzyme is more heat stable, losing only 10% activity after heating for 30 min, compared with 95% for the NAD+-dependent enzyme. It is concluded that in Psychrobacter sp. TAD1 not only does NAD+-dependent GDH have a novel subunit molecular weight and arrangement, but that its polypeptide chains are folded differently from those of NADP+-dependent GDH, providing different cold-active properties to the two enzymes.

Adaptation, Physiological↗

PubMed2000

NADP+-dependent glutamate dehydrogenase in the Antarctic psychrotolerant bacterium Psychrobacter sp. TAD1. Characterization, protein and DNA sequence, and relationship to other glutamate dehydrogenases.

The Antarctic psychrotolerant bacterium Psychrobacter sp. TAD1 contains two distinct glutamate dehydrogenases (GDH), each specific for either NADP+ or NAD+. This feature is quite unusual in bacteria, which generally have a single GDH. NADP+-dependent GDH has been purified to homogeneity and the gene encoding GDH has been cloned and expressed. The enzyme has a hexameric structure. The amino acid sequence determined by peptide and gene analyses comprises 447 residues, yielding a protein with a molecular mass of 49 285 Da. The sequence shows homology with hexameric GDHs, with identity levels of 52% and 49% with Escherichia coli and Clostridium symbiosum GDH, respectively. The coenzyme-binding fingerprint motif GXGXXG/A (common to all GDHs) has Ser at the last position in this enzyme. The overall hydrophilic character is increased and a five-residue insertion in a loop between two alpha-helices may contribute to the increase in protein flexibility. Psychrobacter sp. TAD1 GDH apparent temperature optimum is shifted towards low temperatures, whereas irreversible heat inactivation occurs at temperatures similar to those of E. coli GDH. The catalytic efficiency in the temperature range 10-30 degrees C is similar or lower than that of E. coli GDH. Unlike E. coli GDH the enzyme exhibits marked positive cooperativity towards 2-oxoglutarate and NADPH. This feature is generally absent in prokaryotic GDHs. These observations suggest a regulatory role for this GDH, the most crucial feature being the structural/functional properties required for fine regulation of activity, rather than the high catalytic efficiency and thermolability encountered in several cold-active enzymes.

Amino Acid Motifs↗

PubMed2004

Psychrobacter nivimaris sp. nov., a heterotrophic bacterium attached to organic particles isolated from the South Atlantic (Antarctica).

An aggregate-attached bacterium, strain 88/2-7, was isolated from samples of the Southern Ocean and investigated in a polyphasic approach. The novel marine isolate is an aerobic, Gram-negative, oxidase- and catalase-positive, non-motile short rod and grows in form of cream-colored colonies. Growth was observed at 5-35 degrees C. The bacterium tolerated concentrations of 0-13% (w/v) NaCl and utilized a relatively restricted spectrum of carbon sources. The analysis of the fatty acids revealed 18:1 cis 9 (18:1omega9c) as main fatty acid. The G+C content of the DNA was approximately 42 mol%. The sequence of the 16S rDNA assigned strain 88/2-7 to the gamma-subclass of Proteobacteria with a similarity of 99.65% to Psychrobacter proteolyticus (DSM 13887T). A DNA-DNA-hybridization study showed only 26.8% renaturation to the respective strain. Based on the morphological, physiological and molecular properties of the new isolate, the name Psychrobacter nivimaris sp. nov. (type strain 88/2-7T) is proposed.

Antarctic Regions↗

PubMed2007

A proteomic analysis of Psychrobacter articus 273-4 adaptation to low temperature and salinity using a 2-D liquid mapping approach.

Psychrobacter 273-4 was isolated from a 20,000-40,000-year-old Siberian permafrost core, which is characterized by low temperature, low water activity, and high salinity. To explore how 273-4 survives in the permafrost environment, proteins in four 273-4 samples cultured at 4 and 22 degrees C in media with and without 5% sodium chloride were profiled and comparatively studied using 2-D HPLC and MS. The method used herein involved fractionation via a pH gradient using chromatofocusing followed by nonporous silica (NPS) RP-HPLC and on-line electrospray mass mapping. It was observed that 33 proteins were involved in the adaptation to low temperature in the cells grown in the nonsaline media while there were only 14 proteins involved in the saline media. There were 45 proteins observed differentially expressed in response to salt at 22 degrees C while there were 22 proteins at 4 degrees C. In addition, 5% NaCl and 4 degrees C showed a combination effect on protein expression. A total of 56 proteins involved in the adaptation to low temperature and salt were identified using MS and database searching. The differentially expressed proteins were classified into different functional categories where the response of the regulation system to stress appears to be very elaborate. The evidence shows that the adaptation of 273-4 is based primarily on the control of translation and transcription, the synthesis of proteins (chaperones) to facilitate RNA and protein folding, and the regulation of metabolic pathways.

Acclimatization↗

PubMed2006

Proteomic analysis of Psychrobacter cryohalolentis K5 during growth at subzero temperatures.

It is crucial to examine the physiological processes of psychrophiles at temperatures below 4 degrees C, particularly to facilitate extrapolation of laboratory results to in situ activity. Using two dimensional electrophoresis, we examined patterns of protein abundance during growth at 16, 4, and -4 degrees C of the eurypsychrophile Psychrobacter cryohalolentis K5 and report the first identification of cold inducible proteins (CIPs) present during growth at subzero temperatures. Growth temperature substantially reprogrammed the proteome; the relative abundance of 303 of the 618 protein spots detected (approximately 31% of the proteins at each growth temperature) varied significantly with temperature. Five CIPs were detected specifically at -4 degrees C; their identities (AtpF, EF-Ts, TolC, Pcryo_1988, and FecA) suggested specific stress on energy production, protein synthesis, and transport during growth at subzero temperatures. The need for continual relief of low-temperature stress on these cellular processes was confirmed via identification of 22 additional CIPs whose abundance increased during growth at -4 degrees C (relative to higher temperatures). Our data suggested that iron may be limiting during growth at subzero temperatures and that a cold-adapted allele was employed at -4 degrees C for transport of iron. In summary, these data suggest that low-temperature stresses continue to intensify as growth temperatures decrease to -4 degrees C.

Adaptation, Physiological↗

PubMed2004

Cold-active esterase from Psychrobacter sp. Ant300: gene cloning, characterization, and the effects of Gly-->Pro substitution near the active site on its catalytic activity and stability.

The gene encoding an esterase (PsyEst) of Psychrobacter sp. Ant300, a psychrophilic bacterium isolated from Antarctic soil, was cloned, sequenced, and expressed in Escherichia coli. PsyEst, which is a member of hormone-sensitive lipase (HSL) group of the lipase/esterase family, is a cold-active, themolabile enzyme with high catalytic activity at low temperatures (5-25 degrees C), low activation energy (e.g., 4.6 kcal/mol for hydrolysis of p-nitrophenyl butyrate), and a t(1/2) value of 16 min for thermal inactivation during incubation at 40 degrees C and pH 7.9. A three-dimensional structural model of PsyEst predicted that Gly(244) was located in the loop near the active site of PsyEst and that substitution of this amino-acid residue by proline should potentially rigidify the active-site environment of the enzyme. Thus, we introduced the Gly(244)-->Pro substitution into the enzyme. Stability studies showed that the t(1/2) value for thermal inactivation of the mutant during incubation at 40 degrees C and pH 7.9 was 11.6 h, which was significantly greater than that of the wild-type enzyme. The k(cat)/K(m) value of the mutant was lower for all substrates examined than the value of the wild type. Moreover, this amino-acid substitution caused a shift of the acyl-chain length specificity of the enzyme toward higher preference for short-chain fatty acid esters. All of these observations could be explained in terms of a decrease in active-site flexibility brought about by the mutation and were consistent with the hypothesis that cold activity and thermolability arise from local flexibility around the active site of the enzyme.

Amino Acid Sequence↗

PubMed2026

Psychrobacter sp. XL111, a novel bacterial species from hadal amphipods: genomic insights into environmental adaptation and biotechnological potential.

The hadal zone presents one of the most extreme environments on Earth. While amphipods dominate this realm, the adaptive mechanisms of their resident gut microbiota are not fully understood, which is essential both for understanding the limits of life and for unlocking novel microbial resources. This study investigates Psychrobacter sp. XL111, a novel bacterial species isolated from the gut of hadal amphipods, to elucidate its survival strategies and biotechnological potential. Pan-genome analysis confirms the high genomic plasticity of this genus and highlights the genomic innovations in genes related to environmental adaptation. Genomic analysis revealed specialized adaptations to the deep-sea niche, including expansions in signal transduction systems, pathways for degrading complex organics and the capacity to synthesize stress-resistant compounds. A notable loss of oligosaccharide transporters alongside an enrichment of glycosyltransferases suggests a distinctive evolutionary reconfiguration of carbohydrate metabolism. Functional characterization confirmed that the strain produces an exopolysaccharide with potent radical-scavenging activity, underscoring a key mechanism for mitigating oxidative stress. Our results position hadal micro-organisms as a valuable source of novel enzymes and bioactive molecules for industrial and biomedical applications.

Animals↗

PubMed2006

Predominance of Roseobacter, Sulfitobacter, Glaciecola and Psychrobacter in seawater collected off Ushuaia, Argentina, Sub-Antarctica.

Bacterial diversity in sub-Antarctic seawater, collected off Ushuaia, Argentina, was examined using a culture independent approach. The composition of the 16S rRNA gene libraries from seawater and seawater contaminated with the water soluble fraction of crude oil was statistically different (P value 0.001). In both libraries, clones representing the Alphaproteobacteria, Gammaproteobacteria, the Cytophaga-Flavobacterium-Bacteroidetes group and unculturable bacteria were dominant. Clones associated with the genera Roseobacter, Sulfitobacter, Staleya, Glaciecola, Colwellia, Marinomonas, Cytophaga and Cellulophaga were common to both the libraries. However, clones associated with Psychrobacter, Arcobacter, Formosa algae, Polaribacter, Ulvibacter and Tenacibaculum were found only in seawater contaminated with hydrocarbons (Table 1). Further, the percentage of clones of Roseobacter, Sulfitobacter and Glaceicola was high in seawater (43%, 90% and 12% respectively) compared to seawater contaminated with hydrocarbons (35%, 4% and 9% respectively). One of the clones F2C63 showed 100% similarity with Marinomonas ushuaiensis a bacterium identified by us from the same site.

Alteromonadaceae↗

PubMed2004

Relationship of critical temperature to macromolecular synthesis and growth yield in Psychrobacter cryopegella.

Most microorganisms isolated from low-temperature environments (below 4 degrees C) are eury-, not steno-, psychrophiles. While psychrophiles maximize or maintain growth yield at low temperatures to compensate for low growth rate, the mechanisms involved remain unknown, as does the strategy used by eurypsychrophiles to survive wide ranges of temperatures that include subzero temperatures. Our studies involve the eurypsychrophilic bacterium Psychrobacter cryopegella, which was isolated from a briny water lens within Siberian permafrost, where the temperature is -12 degrees C. P. cryopegella is capable of reproducing from -10 to 28 degrees C, with its maximum growth rate at 22 degrees C. We examined the temperature dependence of growth rate, growth yield, and macromolecular (DNA, RNA, and protein) synthesis rates for P. cryopegella. Below 22 degrees C, the growth of P. cryopegella was separated into two domains at the critical temperature (T(critical) = 4 degrees C). RNA, protein, and DNA synthesis rates decreased exponentially with decreasing temperatures. Only the temperature dependence of the DNA synthesis rate changed at T(critical). When normalized to growth rate, RNA and protein synthesis reached a minimum at T(critical), while DNA synthesis remained constant over the entire temperature range. Growth yield peaked at about T(critical) and declined rapidly as temperature decreased further. Similar to some stenopsychrophiles, P. cryopegella maximized growth yield at low temperatures and did so by streamlining growth processes at T(critical). Identifying the specific processes which result in T(critical) will be vital to understanding both low-temperature growth and growth over a wide range of temperatures.

Bacterial Proteins↗

PubMed2000

A rolling-circle plasmid from Psychrobacter sp. TA144: evidence for a novel rep subfamily.

In this paper we report the cloning and sequencing of two small plasmids, pTAUp and pTADw, from the Antarctic Gram-negative Psychrobacter sp strain TA144. The observation that pTAUp contains a putative Rep-coding gene (Psyrep) suggested that its duplication occurs via a rolling-circle replication mechanism. This hypothesis was confirmed by the identification of the pTAUp single-stranded DNA form. The putative pTAUp plus origin of replication was found at the 3' end of the Psyrep by using an in vivo complementation assay. Structural similarities at the level of (i) gene organization, (ii) protein sequence, and (iii) nick site sequences strongly suggest that the psychrophilic enzyme belongs to a new subfamily of replication enzymes.

Amino Acid Sequence↗

PubMed2001

A new isolation method for labyrinthulids using a bacterium, Psychrobacter phenylpyruvicus.

A new isolation method for labyrinthulids, marine microbes with spindle-shaped vegetative cells and gliding movement, is presented. The method for isolating labyrinthulids has been found to be more difficult and less reproducible than that for thraustochytrids, classified in the same order. So far serum seawater agar fortified with antibiotics has been proposed to be the best for isolation of labyrinthulids. The method presented here involves placing plant samples on an agar medium on which a marine bacterium, Psychrobacter phenylpyruvicus, has been grown. The new method, which utilizes fallen mangrove leaves as source material, was more than twice as effective as isolation agar medium without the bacterium. The increased effectiveness appears to derive partly from the bacterial colonies' delaying extension of fungal mycelium. The bacterium was more effective for the isolation of labyrinthulids than either the bacterium Shewanella sp. or the yeast Rhodotorula rubra.

Journal Article↗

PubMed1993

Cloning, sequence and structural features of a lipase from the antarctic facultative psychrophile Psychrobacter immobilis B10.

A lipase gene (lip1) from the facultative psychrophilic strain Psychrobacter immobilis B10 has been cloned and sequenced. The deduced preprotein sequence is composed of 317 amino acids with a predicted M(r) of 35,288. A primary structure alignment of lipases including lip1 shows conserved elements for which a structural role is proposed in the light of recent crystallographic studies. The analysis of the psychrophilic enzyme sequence suggests characteristics in relation with the adaptation to cold.

Amino Acid Sequence↗