Diversity and distribution of Klebsiella capsules in Escherichia coli.

E. coli strains responsible for elevated counts (blooms) in freshwater reservoirs in Australia carry a capsule originating from Klebsiella. The occurrence of Klebsiella capsules in E. coli was about 7% overall and 23 different capsule types were detected. Capsules were observed in strains from phylogroups A, B1 and C, but were absent from phylogroup B2, D, E and F strains. In general, few A, B1 or C lineages were capsule-positive, but when a lineage was encapsulated multiple different capsule types were present. All Klebsiella capsule-positive strains were of serogroups O8, O9 and O89. Regardless of the phylogroup, O9 strains were more likely to be capsule-positive than O8 strains. Given the sequence similarity, it appears that both the capsule region and the O-antigen gene region are transferred to E. coli from Klebsiella as a single block via horizontal gene transfer events. Pan genome analysis indicated that there were only modest differences between encapsulated and non-encapsulated strains belonging to phylogroup A. The possession of a Klebsiella capsule, but not the type of capsule, is likely a key determinant of the bloom status of a strain.

Biohydrogen production from fermentation of cotton stalk hydrolysate by Klebsiella sp. WL1316 newly isolated from wild carp (Cyprinus carpio L.) of the Tarim River basin.

A new hydrogen-producing bacterium was isolated from the intestine of wild carp (Cyprinus carpio L.) of the Tarim River Basin. The isolate was identified as Klebsiella sp. based on 16S rDNA gene sequencing and examination of physiological and biochemical characteristics. The isolated strain, Klebsiella sp. WL1316, could effectively produce a high yield of hydrogen by using cotton stalk hydrolysate as substrate. The optimum fermentation conditions for hydrogen production were determined as follows: an initial sugar concentration of 40 g/L, a fermentation temperature of 37 °C and an initial pH value of 8.0. The scaled-up fermentation process was conducted in a 5-L fermenter using these parameters. Higher productivities with maximum daily hydrogen production of 937.0 ± 41.0 mL L-1 day-1, cumulative hydrogen production of 2908.5 ± 47.4 mL L-1, viable cell count of (20.2 ± 0.6) × 108 CFU mL-1 and hydrogen yield of 1.44 ± 0.08 mol mol-1sugarconsumed were obtained. The cumulative hydrogen production was predicted by the modified Gompertz equation with R 2 of 0.997, and values of R m and P were 44.8 mL L-1 h-1 and 3057.6 mL L-1, respectively. These results indicated that the strain Klebsiella sp. WL1316 resulted in a high hydrogen production rate (HPR) and good hydrogen production potential. Moreover, this strain exhibited higher values of maximum hydrogen yield and HPR than the reported pure cultures.

Abiotic process for Fe(II) oxidation and green rust mineralization driven by a heterotrophic nitrate reducing bacteria (Klebsiella mobilis).

Green rusts (GRs) are mixed Fe(II)-Fe(III) hydroxides with a high reactivity toward organic and inorganic pollutants. GRs can be produced from ferric reducing or ferrous oxidizing bacterial activities. In this study, we investigated the capability of Klebsiella mobilis to produce iron minerals in the presence of nitrate and ferrous iron. This bacterium is well-known to reduce nitrate using an organic carbon source as electron donor but is unable to enzymatically oxidize Fe(II) species. During incubation, GR formation occurred as a secondary iron mineral precipitating on cell surfaces, resulting from Fe(II) oxidation by nitrite produced via bacterial respiration of nitrate. For the first time, we demonstrate GR formation by indirect microbial oxidation of Fe(II) (i.e., a combination of biotic/abiotic processes). These results therefore suggest that nitrate-reducing bacteria can potentially contribute to the formation of GR in natural environments. In addition, the chemical reduction of nitrite to ammonium by GR is observed, which gradually turns the GR into the end-product goethite. The nitrogen mass-balance clearly demonstrates that the total amount of ammonium produced corresponds to the quantity of bioreduced nitrate. These findings demonstrate how the activity of nitrate-reducing bacteria in ferrous environments may provide a direct link between the biogeochemical cycles of nitrogen and iron.

Simultaneous production of 2,3-butanediol, ethanol and hydrogen with a Klebsiella sp. strain isolated from sewage sludge.

A Klebsiella sp. HE1 strain isolated from hydrogen-producing sewage sludge was examined for its ability to produce H2 and other valuable soluble metabolites (e.g., ethanol and 2,3-butanediol) from sucrose-based medium. The effect of pH and carbon substrate concentration on the production of soluble and gaseous products was investigated. The major soluble metabolite produced from Klebsiella sp. HE1 was 2,3-butanediol, accounting for over 42-58% of soluble microbial products (SMP) and its production efficiency enhanced after increasing the initial culture pH to 7.3 (without pH control). The HE1 strain also produced ethanol (contributing to 29-42% of total SMP) and a small amount of lactic acid and acetic acid. The gaseous products consisted of H2 (25-36%) and CO2 (64-75%). The optimal cumulative hydrogen production (2.7 l) and hydrogen yield (0.92mol H2 mol sucrose(-1)) were obtained at an initial sucrose concentration of 30g CODl(-1) (i.e., 26.7gl(-1)), which also led to the highest production rate for H2 (3.26mmol h(-1)l(-1)), ethanol (6.75mmol h(-1)l(-1)) and 2,3-butanediol (7.14mmol h(-1)l(-1)). The highest yield for H2, ethanol and 2,3-butanediol was 0.92, 0.81 and 0.59molmol-sucrose(-1), respectively. As for the overall energy production performance, the highest energy generation rate was 27.7kJ h(-1)l(-1) and the best energy yield was 2.45kJmolsucrose(-1), which was obtained at a sucrose concentration of 30 and 20g CODl(-1), respectively.

Bacterial counts in organic materials used as free-stall bedding following treatment with a commercial conditioner.

An acidic conditioner was tested in recycled manure and sawdust used as free-stall bedding to determine the effect on bacterial counts of common environmental mastitis pathogens. Free stalls were bedded with 10 kg of either kiln-dried sawdust or recycled manure per stall. All bedding was removed and fresh bedding was applied every 7 d. Approximately 1 kg of commercial bedding conditioner containing 93% sodium hydrosulfate (wt/wt) was spread evenly over bedding in the back one-third of each treated stall. Control bedding received no treatment. Cows were bedded on the same material for 3 consecutive weeks. After 3 wk on a bedding treatment, cows remained in the same pens and bedding treatments were changed between rows within pens in a switchback design. The addition of bedding conditioner to sawdust reduced gram-negative bacterial, coliform, Klebsiella spp., and streptococcal counts immediately after application and 1 d after application. Bacterial counts did not differ between treated and untreated sawdust on d 2 and 6 after the conditioner treatment. Each bacterial count measured was reduced in recycled manure immediately after application. Gram-negative bacterial and streptococcal counts were reduced in treated recycled manure compared with untreated recycled manure on d 1 after conditioner was applied. Bacterial counts did not differ between treated and untreated recycled manure bedding on d 2 and 6 after application in free stalls. The antibacterial activity of the conditioner was related to the pH of the bedding and was diminished by d 2 after application in both bedding types.

Klebsiella singaporensis sp. nov., a novel isomaltulose-producing bacterium.

Cells of strain LX3(T), isolated from soil, were Gram-negative, facultatively anaerobic, non-motile, capsulated and non-endospore-forming straight rods, able to grow at 10 degrees C, unable to produce gas from lactose at 45 degrees C and unable to produce indole. The isolate converted sucrose to isomaltulose and did not produce detectable glucose by-products. The G+C content of the DNA was 56.4 mol%. Furthermore, comparison of 16S rRNA and rpoB gene sequences showed that the isolate clearly belongs to the genus Klebsiella. The closest phylogenetic relative was Klebsiella pneumoniae, there being 99.3 and 97.5 % similarity in 16S rRNA and rpoB gene sequences, respectively. DNA-DNA hybridization analysis demonstrated a very low level of relatedness to other members of the genus Klebsiella, indicating that the isolated strain and other species in the genus Klebsiella were not related at the species level. The isolate could be differentiated from other previously described members of the genus Klebsiella on the basis of phenotypic differences and 16S rRNA and rpoB gene sequence divergence, together with DNA-DNA reassociation data. Therefore, it is proposed that strain LX3(T) (=DSM 16265(T)=JCM 12419(T)) should be classified as the type strain of a novel species of genus Klebsiella, Klebsiella singaporensis sp. nov.

Potent antibacterial activity of halogenated metabolites from Malaysian red algae, Laurencia majuscula (Rhodomelaceae, Ceramiales).

Red algae genus Laurencia (Rhodomelaceae, Ceramiales) are known to produce a wide range of chemically interesting secondary halogenated metabolites. This investigation delves upon extraction, isolation, structural elucidation and antibacterial activity of inherently available secondary metabolites of Laurencia majuscula Harvey collected from two locations in waters of Sabah, Malaysia. Two major halogenated compounds, identified as elatol (1) and iso-obtusol (2) were isolated. Structures of these compounds were determined from their spectroscopic data such as IR, 1H-NMR, 13C-NMR and optical rotation. Antibacterial bioassay against human pathogenic bacteria was conducted using disc diffusion (Kirby-Bauer) method. Elatol (1) inhibited six species of bacteria, with significant antibacterial activities against Staphylococcus epidermis, Klebsiella pneumonia and Salmonella sp. while iso-obtusol (2) exhibited antibacterial activity against four bacterial species with significant activity against K. pneumonia and Salmonella sp. Elatol (1) showed equal and better antibacterial activity compared with tested commercial antibiotics while iso-obtusol (2) only equaled the potency of commercial antibiotics against K. pneumonia and Salmonella sp. Further tests conducted using dilution method showed both compounds as having bacteriostatic mode of action against the tested bacteria.

Induction of 4-hydroxycinnamate decarboxylase in Klebsiella oxytoca cells exposed to substrates and non-substrate 4-hydroxycinnamate analogs.

The 4-hydroxycinnamate decarboxylase (4-HCD)-inducing activity of several substrate analogs toward Klebsiella oxytoca was investigated. Four E-cinnamate-class compounds, E-4-hydroxycinnamic acid (1), caffeic acid (2), ferulic acid (3) and E-2,4-dihydroxycinnamic acid (4), all of which were accepted as substrates, all of which were accepted as substrates of 4-HCD, enable K. oxytoca cells to induce the decarboxylase at a 2.0 mM concentration, while five non-substrate compounds of the E-cinnamate class so far tested were completely inactive. However, 6-hydroxy-2-naphthoic acid (11) and 7-hydroxycoumarin 3-carboxylic acid (14), both of which are non-cinnamate-class analogs of the substrate, acted as strong 4-HCD inducers, even at a 0.5 mM concentration. The 4-HCD-inducing activities of compounds 11 and 14 at 0.5 mM were 10-12-fold higher than that of substrate 1. Compound 11 maintained its 4-HCD-inducing activity toward cultured cells through the late-log and stationary phases, unlike 1 that induced 4-HCD only in the early log phase. SDS-PAGE electrophoresis of protein mixtures from the cultured cells exposed to any 4-HCD inducer indicated that the 21.5 kDa protein was always present.

Phylogenetic evidence for reclassification of Calymmatobacterium granulomatis as Klebsiella granulomatis comb. nov.

By sequencing a total of 2089 bp of the 16S rRNA and phoE genes it was demonstrated that Calymmatobacterium granulomatis (the causative organism of donovanosis) shows a high level of identity with Klebsiella species pathogenic to humans (Klebsiella pneumoniae, Klebsiella rhinoscleromatis). It is proposed that C. granulomatis should be reclassified as Klebsiella granulomatis comb. nov. An emended description of the genus Klebsiella is given.

Cytologic diagnosis of rhinoscleroma.

The cytologic diagnosis of a case of rhinoscleroma was made on brushing specimens of a laryngeal lesion. The cytologic picture included aggregates of the characteristic Mikulicz cells, large, rounded histiocytes with an eccentric nucleus and vacuolar cytoplasm containing the short rods of Klebsiella rhinoscleromatis. Although the diagnosis of this chronic infectious disease involving the upper respiratory tract is routinely made by tissue biopsy and bacteriologic study of the lesions, the present report indicates that cytology has a definite place in its diagnosis.

Isolation of a salt tolerant pleomorphic Klebsiella strain from a case of diabetic periodontitis.

An unusual Klebsiella strain was isolated from a deep periodontal pocket of a diabetic patient. According to its biochemical reactions the new strain differed from Klebsiella pneumoniae and other described biotypes. In addition, the new isolate was very salt tolerant; in the presence of 7.5% sodium chloride the bacterium changed into a spirillum-like form, with highly pleomorphic filaments, and reverted immediately to the short rod form at lower sodium chloride concentrations or in the absence of sodium chloride. Optimum growth was observed in the presence of 2% sodium chloride. A wide range of carbohydrates was fermented with a large amount of gas production. It appears that the adaptation of the isolated Klebsiella strain to sodium chloride allows it to enter the ecological niche of periodontal lesions.

[Morphological studies on antibacterial activities of cefotiam (author's transl)].

1. Cefotiam was demonstrated to be more potent than cefazolin in its antibacterial activities against clinical isolates of E. coli, Klebsiella, Serratia, Proteus mirabilis, Proteus morganii and Proteus inconstans. MICs of cefotiam with 10(6) cells/ml inoculum size were considerably lower than those with 10(8) cells/ml. 2. Organisms lysed when exposed to cefotiam at concentrations higher than the MICs with 10(8) cells/ml. Morphological changes of organisms into filament occurred even at concentrations lower than the MICs with 10(6) cells/ml. This indicates that cefotiam is incorporated into organisms at remarkably low concentrations and exerts its antibacterial activities. 3. Cefotiam showed a high affinity for penicillin-binding proteins (PBP) 1A, 1Bs and 3. The formation of filament at low concentrations of cefotiam is possibly attributable to the high affinity of cefotiam for PBP 3 in addition to its high permeability through outer cell membrane. 4. As the antibacterial activities of cefotiam are displayed at lower concentrations, it is reasonable to consider that doses of cefotiam on clinical use can be reduced in comparison with those of conventional cephalosporins.

Klebsiella rhinoscleromatis: a clinical and pathogenic enigma.

Rhinoscleroma is a chronic, slowly progressive, infectious disease of the respiratory tract that can produce disability and death, if untreated. Once considered an anomaly in the United States, the disease is now seen more frequently in this country, owing to increased travel from endemic areas. This report presents a comprehensive review of the several types of therapy that have been published in the literature. The results of a clinical experiment are also presented.