Identification of a slime exopolysaccharide depolymerase in mucoid strains ofPseudomonas aeruginosa

Strains ofPseudomonas aeruginosa recovered from pulmonary infections in cystic fibrosis (CF) patients are often mucoid in appearance owing to the secretion of a viscous slime exopolysaccharide (EPS). Unlike most mucoid isolates, strains WcM#2, P10, and P11 produce mucoid colonies after 24 h of incubation at 37°C, which become nonmucoid upon further incubation; this suggests the presence of a slime-degrading enzyme or depolymerase. Using both qualitative and quantitative assays, the presence of a slime EPS depolymerase was confirmed in each of these three strains as well as in four of four additional mucoid strains. Depolymerase activity was lower but still detectable in four of four nonmucoid strains. Enzyme preparations from strains WcM#2, P10, and P11 were active on most, but not all, slime EPS preparations fromP. aeruginosa strains, as well as sodium alginate; greater activity was observed on substrates after deacetylation. Comparisons are made between the enzyme described in this study and previous reports of slime EPS depolymerase in mucoid strains ofP. aeruginosa.     

Polysaccharide-producing bacteria isolated from paper machine slime deposits

Development of novel enzymatic methods for slime deposit control in paper mills requires knowledge of polysaccharide-producing organisms and the polysaccharide structures present in deposits. In this work, 27 polysaccharide-producing bacteria were isolated from slime samples collected from different parts of a paper machine. Most of the isolates produced polysaccharides in liquid culture and nine of them were selected for production of polysaccharides for characterisation. The selected isolates belonged to seven different genera: Bacillus, Brevundimonas, Cytophaga, Enterobacter, Klebsiella, Paenibacillus and Starkeya. Using ribotyping, partial 16S rDNA sequencing, physiological tests and fatty acid analysis, four of the nine isolates: Bacillus cereus, Brevundimonas vesicularis, K. pneumoniae and P. stellifer were identified to the species level. Production of polysaccharides by the selected isolates varied between 0.07 and 1.20 g L^–1, the highest amount being produced by B. vesicularis. The polysaccharides were heteropolysaccharides with varying proportions of galactose, glucose mannose, rhamnose fucose and uronic acids.     

Biodegradation of dissolved jet fuel in chemostat by a mixed bacterial culture isolated from a heavily polluted site

A mixed bacterial culture capable of biodegrading of jet fuel was isolated from a heavily polluted site in Tapa, Estonia. Residual concentrations of pollutants in the chemostat culture were determined. The total residual concentrations of dissolved jet fuel in culture medium were 0.42 and 2.1 μg l^-1 at the dilution rates 0.1 and 0.17 h^-1respectively. Benzene, toluene, ethylbenzene, and xylenes were completely degraded and thus not detected in culture broth (detection limit 0.1 μg l^-1)at the dilution rates 0.1 and 0.17 h^-1. The values of apparent substrate saturation constant(K_Sapp) in multisubstrate growth conditions were estimated from the experimental data. The residual concentrations satisfy the regulations in the Republic of Estonia for petroleum hydrocarbons (0.00 mg l^-1 – ‘very good’). Results obtained indicate that use of the biodegradation could be sufficient for the treatment of polluted with kerosene-type jet fuel groundwater up to the acceptable quality. This revised version was published online in August 2006 with corrections to the Cover Date.     

Characterization of mucoid Pseudomonas aeruginosa strains isolated from technical water systems

The occurrence of mucoid Pseudomonas aeruginosa strains was investigated in water samples and surface material from non-clinical aquatic environments. Ten of 81 environmental isolates displayed a mucoid colony type after incubation at 36°C for 24 h on Pseudomonas Isolation Agar. The mucoid strains obtained exclusively from surfaces of technical water systems were characterized in terms of medium-dependent expression of mucoid colonial phenotype, exoenzyme profile, pigment production and O-antigen type. The mucoid strains secreted substantially higher quantities of carbohydrate and uronic acid-containing material compared to non-mucoid environmental isolates. Major slime components of the mucoid strains were identified as O-acetylated alginates that contained higher proportions of mannuronate than guluronate monomer residues and were composed of blocks of poly-mannuronate and poly-mannuronate/guluronate, whereas blocks of poly-guluronate were absent. The results suggest that surfaces in aquatic environments may represent a natural habitat for mucoid (i.e. alginate-overproducing) strains of Ps. aeruginosa with properties similar to clinical mucoid strains.     

Some properties of vacuoles isolated from Neurospora crassa slime variant

A method for the isolation of vacuoles based on polybase induced lysis of protoplasts of the cell wall deficient Neurospora crassa slime variant is described. Isolated vacuoles are characterized by 12 to 50 times increased specific activities of several hydrolases as compared with the total homogenate of protoplasts. Total -amino nitrogen, arginine, and polyphosphate are also greatly enriched in these vacuoles. Vacuoles are equipped with a permease for the transport of basic amino acids across the tonoplast.Non-Standard Abbreviation DEAE-dextran diethylaminoethyl-dextran     

Two new species ofPichia isolated from slime fluxes of deciduous trees

Two new homothallic species ofPichia, associated with exudates ofPopulus trichocarpa andSalix sp. have been described.Pichia trehalophila sp.n. was isolated from slime exudates in two widely separatedPopulus trichocarpa trees andPichia salictaria sp.n. was isolated from two exudates ofSalix sp. The latter species was previously present as an unidentified strain ofPichia in the culture collection of the Centraalbureau voor Schimmelcultures and had been isolated from a patient in Germany. The natural habitat ofP. salictaria is considered to be in association with willow trees.     

Psychrophilic yeasts isolated from marine fish

Yeasts were isolated from marine fish using low incubation temperatures. The isolates were screened for their ability to grow at 4 C and 30 C. Isolates growing at 4 C but not at 30 C were considered to be psychrophilic and were selected for further study. Approximately 25% of the isolates were in this category. The isolates comprised the following genera:Candida, Cryptococcus, Debaryomyces, Rhodotorula, Torulopsis andTrichosporon. Rhodotorula infirmo-miniata accounted for 50% of the isolates andTrichosporon pullulans 10%. Other species were present in numbers below the 10% level. The distribution of the species between the two sample areas is discussed. The vitamin requirements and optimum growth temperatures of the isolates were assessed.     

Characteristics of a new reovirus isolated from epizootic ulcerative syndrome infected snakehead fish.

Epizootic ulcerative syndrome (EUS) has been infecting a wide range of fishes in the South and Southeast Asia for the last 2 decades. One reovirus-like agent (snakehead reovirus, SKRV), isolated from an EUS-infected snakehead fish and investigated in the present study, is the only reovirus so far isolated from an EUS-infected fish. SKRV was characterised by the presence of a double-stranded RNA genome with icosahedral symmetry and double capsid. The virus had an average size of 71 nm, a buoyant density of 1.36 g ml(-1) in CsCl and lacked a lipid-containing envelope. Apart from the above, the presence of a segmented genome and structural proteins falling into 3 specific size classes confirmed that the virus belongs to the family Reoviridae. SKRV differed from aquareoviruses by the lack of a cytopathic effect (CPE) with syncitium formation and in the segmentation pattern of RNA genome. The resistance to pH (3.0 to 9.0) and heat treatment and inability to multiply in mammalian cell lines and haemagglutinate human 'O' red blood cells (RBCs) differentiated SKRV from the rest of the similar genera in the family Reoviridae. Serological comparison indicated the antigenic distinctness of the isolate from selected American and European aquareoviruses. SKRV grew well in SSN-1 and SSN-3 cells at 25 to 30 degrees C but not in the most common Aquareovirus susceptible coldwater fish cell line--CHSE-214.     

The biological characteristics of micromycetes isolated from fish roe

The fungi Aspergillus fumigatus Fres., and Fusarium sporotrichiella Bilai were studied for their effect on certain biochemical indices of two-year carp and spawn of grass carp under laboratory conditions. The intraperitoneal introduction of A. fumigatus in a dose of 5 and 20 min conidia per individual to two-year carp decreased significantly the protein level in blood serum, the decrease being more considerable with the introduction of the smaller dose of fungal conidia. Joint incubation of the grass carp spawn and F. sporotrichiella induced changes in the protein level, amylolytic and phosphate (acid phosphatase) activity in spawn. In that case the time of the fungus action on grass carp spawn was a decisive factor. Activity of certain hydrolytic enzymes in mycelium and conidia of A. fumigatus and F. sporotrichiella was determined. The amylolytic activity was not revealed in the checked samples. The proteolytic activity was established in all samples of fungi and culture liquid, the highest level being observed in mycelia and conidia of A. fumigatus. The alkaline and acid phosphatase activity was found in F. sporotrichiella: the acid phosphatase activity was higher in mycelium, the acid phosphatase one in the fungus conidia. The problem on the A. fumigatus ability to produce extracellular enzymes is under discussion.     

Chararacteristics of Vagococcus salmoninarum isolated from diseased salmonid fish

Isolates of the salmonid pathogen Vagococcus salmoninarum were recovered from Atlantic salmon, rainbow trout and brown trout with peritonitis. The phenotypes of these isolates and the type strain of Vag. salmoninarum NCFB 2777 were determined by morphological, biochemical and physiological tests and whole cell protein profiles by SDS-PAGE. There was a high level of phenetic similarity between the salmonid isolates and the type strain. The species forms short Gram-positive rods, hydrolyses L-pyrrolidonyl-β-naphthylamide, is α-haemolytic on sheep's blood agar, grows at pH 9·6 and 10°C but not at 40°C or in 6·5% NaCl and is catalase-negative; a Lancefield group N antigen is not present. Vagococcus salmoninarum can be distinguished phenetically from similar fish pathogens including Carnobacterium piscicola, Enterococcus seriolicida and Lactococcus piscium.     

First bacterial chalcone isomerase isolated from Eubacterium ramulus

The human fecal anaerobe Eubacterium ramulus is capable of degrading various flavonoids, including the flavone naringenin. The first step in the proposed degradation pathway is the isomerization of naringenin to the corresponding chalcone. Cell-free extracts of E. ramulus displayed chalcone isomerase activity. The enzyme from E. ramulus was purified to homogeneity. Its apparent molecular mass was estimated to be 136 and 129 kDa according to gel filtration and native polyacrylamide gel electrophoresis, respectively. Chalcone isomerase is composed of one type of subunit of 30 kDa. The purified enzyme catalyzed the isomerization of naringenin chalcone, isoliquiritigenin, and butein, three chalcones that differ in their hydroxylation pattern. N-bromosuccinimide, but also naringenin and phloretin, inhibited the purified enzyme considerably. This is the first report on a bacterial chalcone isomerase. The physiological function of the purified enzyme is unclear, but an involvement in the conversion of the flavanone naringenin to the chalcone is proposed.     

Characterization of corrosive bacterial consortia isolated from petroleum-product-transporting pipelines

Microbiologically influenced corrosion is a problem commonly encountered in facilities in the oil and gas industries. The present study describes bacterial enumeration and identification in diesel and naphtha pipelines located in the northwest and southwest region in India, using traditional cultivation technique and 16S rDNA gene sequencing. Phylogenetic analysis of 16S rRNA sequences of the isolates was carried out, and the samples obtained from the diesel and naphtha-transporting pipelines showed the occurrence of 11 bacterial species namely Serratia marcescens ACE2, Bacillus subtilis AR12, Bacillus cereus ACE4, Pseudomonas aeruginosa AI1, Klebsiella oxytoca ACP, Pseudomonas stutzeri AP2, Bacillus litoralis AN1, Bacillus sp., Bacillus pumilus AR2, Bacillus carboniphilus AR3, and Bacillus megaterium AR4. Sulfate-reducing bacteria were not detected in samples from both pipelines. The dominant bacterial species identified in the petroleum pipeline samples were B. cereus and S. marcescens in the diesel and naphtha pipelines, respectively. Therefore, several types of bacteria may be involved in biocorrosion arising from natural biofilms that develop in industrial facilities. In addition, localized (pitting) corrosion of the pipeline steel in the presence of the consortia was observed by scanning electron microscopy analysis. The potential role of each species in biofilm formation and steel corrosion is discussed.     

Characteristics of leucine transport by isolated hepatocytes of antarctic fish at low temperatures

Hepatocytes prepared by collagenase perfusion from Antarctic nototheniid fish of genus Trematomus are active in uptake of [¹⁴C]leucine at 0, 5, and 10°C. The system is saturable with apparent $\text{K}{}_{\mathrm{<mtext>m</mtext>}}$ about 1.0 mM. Isoleucine and phenylalanine were major competitors, valine was about one-half as effective, while alanine, glycine and histidine had no effect. Temperature dependency of rates in the 0–10°C range yielded $\text{E}{}_{\mathrm{<mtext>a</mtext>}}\text{= 65}\text{kJ/mol}$ ($\text{Q}{}_{10}\text{= 2.7}$). The average first-order rate constant at 0°C was 0.1 min^?1, one-third the value of 0.3 min^?1 estimated for clearance of [¹⁴C]leucine by liver of these species in vivo. Affinity and specificity agreed well with in vivo data on liver clearance of leucine, both in Antarctic fish at 0°C and in temperate fish acclimated to 10°C and 20°C. The results indicate similar modifications of leucine transport associated with evolutionary cold adaptation and seasonal acclimation in fish.     

Outer membrane antigens of mucoid Pseudomonas aeruginosa isolated directly from the sputum of a cystic fibrosis patient

Abstract The antigenicity of the outer membrane components of mucoid Pseudomonas aeruginosa directly isolated from the sputum of a cystic fibrosis patient and those of the same isolate cultivated under iron-depleted conditions in the presence of sub-in-hibitory concentrations of piperacillin and/or tobramycin was investigated by immunoblotting using the patient's own serum. The results indicated that iron-regulated membrane proteins as well as other major outer membrane proteins were antigenic and recognised by the patient's serum. The antibiotics used profoundly influenced the surface antigen pattern.     

Antibiotic resistance of Salmonella strains isolated from fish and crustaceans

A total of 240 Salmonella strains, 158 from 730 fish samples and 82 from 276 crustacean samples, obtained during a 2 year period, were examined for resistance to 10 antibiotics. More than 90% of the strains were resistant to bacitracin, penicillin and novobiocin. The least resistance was observed to chloramphenicol (6·7%) and nalidixic acid (12%). Multiple antibiotic resistance indexing of the strains showed that more than 95% originated from high risk sources of contamination such as poultry, swine, cattle and human environments where antibiotics are often used.     

Characteristics of methanogens isolated from bovine rumen

Six strains of methanogens were isolated from 10(-8) and 10(-9) ml of bovine rumen contents. All strains had the morphologic and physiologic characteristics of Methanobrevibacter spp. Four strains required coenzyme M; two did not. Growth of all strains either depended on or was stimulated by a mixture of isobutyric, isovaleric, 2-methylbutyric, and valeric acids. None of the strains reacted with antiserum against the type strain of Methanobrevibacter ruminantium.     

Characteristics of staphylococci isolated from newborn infants

The microflora of the skin and the nasal mucosa was studied in 14 healthy newborns, 3 newborns with purulent infections and a nurse working in a neonatal ward. To make this study, washings were obtained with the use of 0.1% Triton X-100 solution. The determination of the number of microorganisms, the percentage of staphylococci, the percentage of lecithinase-positive staphylococci and the number of colonies with antagonistic properties revealed that these characteristics differed according to the state of health of the newborns and the time elapsed after their birth, and that changes in the number of antagonistically active bacteria occurred in parallel with changes in the total number of bacteria. Among S. aureus strains isolated from the subjects covered by the survey strains belonging to phagovar 80, as well as untyped strains, and among S. epidermidis strains those belonging to biovars I and II occurred most frequently. Strains belonging to the same biovar or phagovar differed in their plasmid markers.