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Two bacterial strains, 46-1 and 46-2 T , were isolated from garden soil. These strains were observed to be aerobic, Gram-stain negative, rod-shaped, non-spore-forming, motile and catalase and oxidase positive. Phylogenetic analysis based on 16S rRNA gene sequences showed that the two strains shared 100 % sequence similarity with each other and belong to the genus Pseudomonas in the class Gammaproteobacteria. The concatenated 16S rRNA, gyrB, rpoB and rpoD gene sequences further confirmed that the isolates belong to the Pseudomonas koreensis subgroup (SG), with P. koreensis Ps 9-14 T , Pseudomonas moraviensis 1B4 T and Pseudomonas granadensis F-278,770 T as their close relatives (>96 % pairwise similarity). DNA-DNA hybridization with the closely related type strain P. koreensis SG revealed a low level of relatedness (<50 %). A cladogram constructed using whole-cell matrix-assisted laser desorption/ionization time-of-flight (WC-MALDI-TOF) MS analysis showed the isolates formed a completely separate monophyletic group. The isolates were negative for utilization of glycogen, D-psicose, α-keto butyric acid, α-keto valeric acid, succinamic acid and D, L-α-glycerol phosphate. In contrast, all these reactions were positive in P. koreensis JCM 14769 T and P. moraviensis DSM 16007 T . The fatty acid C 17:0 cyclo was detected as one of the major cellular fatty acids (>15 %) in the isolates but it was a minor component (<4 %) in both reference type strains. In contrast, the fatty acid, C 12:0 was not observed in the isolates but was present in both reference strains. Based on differences such as phylogenetic position, low-level DNA-DNA hybridization, WC-MALDI-TOF MS analysis, fluorescence pigmentation, fatty acid profiles, and substrate utilization, we propose that the isolates 46-1 and 46-2 T represent a novel species of the genus Pseudomonas, for which the name Pseudomonas kribbensis sp. nov. is proposed; the type strain is 46-2 T (=KCTC 32541 T  = DSM 100278 T ).

A Gram-negative, non-mobile, polar single flagellum, rod-shaped bacterium WZBFD3-5A2(T) was isolated from a wheat soil subjected to herbicides for several years. Cells of strain WZBFD3-5A2(T) grow optimally on Luria-Bertani agar medium at 30 °C in the presence of 0-4.0 % (w/v) NaCl and pH 8.0. 16S rRNA gene sequence analysis revealed that strain WZBFD3-5A2(T) belongs to the genus Pseudomonas. Physiological and biochemical tests supported the phylogenetic affiliation. Strain WZBFD3-5A2(T) is closely related to Pseudomonas nitroreducens IAM1439(T), sharing 99.7 % sequence similarity. DNA-DNA hybridization experiments between the two strains showed only moderate reassociation similarity (33.92 ± 1.0 %). The DNA G+C content is 62.0 mol%. The predominant respiratory quinine is Q-9. The major cellular fatty acids present are C(16:0) (28.55 %), C(16:1ω6c) or C(16:1ω7c) (20.94 %), C(18:1ω7c) (17.21 %) and C(18:0) (13.73 %). The isolate is distinguishable from other related members of the genus Pseudomonas on the basis of phenotypic and biochemical characteristics. From the genotypic, chemotaxonomic and phenotypic data, it is evident that strain WZBFD3-5A2(T) represents a novel species of the genus Pseudomonas, for which the name Pseudomonas nitritereducens sp. nov. is proposed. The type strain is WZBFD3-5A2(T) (=CGMCC 1.10702(T) = LMG 25966(T)).

A soil bacterium SW4, capable of degrading the sulfonylurea herbicide ethametsulfuron-methyl (ESM), was isolated from the bottom soil of a herbicide factory. Based on physiological characteristics, biochemical tests and phylogenetic analysis of the 16S rRNA gene sequence, the strain was identified as a Pseudomonas sp. The total degradation of ESM in the medium containing glucose was up to 84.6% after 6 days of inoculation with SW4 strain. The inoculation of strain SW4 to soil treated with ESM resulted in a higher degradation rate than in noninoculated soil regardless of the soil sterilized or nonsterilized. Five metabolites of ESM degradation were analyzed by liquid chromatography/mass spectrometry. Based on the identified products, strain SW4 seemed to degrade ESM after two separate and different pathways: one leads to the cleavage of the sulfonylurea bridge, whereas the other to the dealkylation and opening of the triazine ring of ESM.

Thirty rhizobacteria isolated from maize grown in Pakistani and Indonesian soils were evaluated for their morphological characteristics, nitrogen fixation, P-solubilization, indole acetic acid (IAA) and siderophores production. Nitrogenase activity was detected in nineteen isolates ranging from 21.8-3624 n moles C2H4 produced/h/mg protein. Most of the isolates produced IAA, ten were capable of siderophore production while four were P-solubilizers. Ultrastructural studies of Pseudomonas sp. F14 indicated characteristic rhizospheric colonization within 48 h that was observed to change considerably with the passage of time from few bacteria to micro colonies. Random amplified polymorphic DNA (RAPD) analysis of 30 bacterial strains using 30 oligonucleotide primers resulted in considerable level of genetic diversity, with genetic distance ranging from 2-16%. Indonesian isolates were found to be more diverse as compared to Pakistani isolates. The characterization and screening of rhizobacteria of maize rhizosphere has helped in selection of isolates F7, LS-1, 3.1.1.C, F2, F3 and F13 as superior strains for use as bioinoculant. Moreover isolate F14 identified, as Pseudomonas fulgida by partial 16S rRNA sequence analysis is a novel strain regarding its tremendous potentials for inoculum production to enhance the yield of maize., (((c) 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim).)

The transfer of catabolic genes on conjugative plasmids to indigenous organisms from which they may spread further into the community allows the introduction of new biodegradative pathways for metabolic conversion of pollutants to the community. Biomonitoring of IncP plasmid pJP4-carrying Pseudomonas chlororaphis from the rhizosphere of Arabidopsis thaliana was achieved using antisera specific for proteins from the plasmid transfer machinery. Antisera were generated that recognized TrbC and TrbF, the putative major and minor components of pJP4-determined pili, respectively, and the putative lipoprotein TrbH. Cell fractionation studies showed association of TrbC, TrbF and TrbH with the cells and suggested that TrbC and TrbF are part of extracellular pJP4-determined pili. TrbF and TrbH antisera allowed specific detection of IncP compared with IncN or IncW plasmid-carrying cells and even permitted differentiation between bacteria carrying IncPalpha plasmid RP4 and IncPbeta plasmid pJP4. Immunofluorescence microscopy was applied to detect TrbF and TrbH signal at the cell periphery, allowing distinction from autofluorescing cells and soil debris. In situ experiments showed specific recognition of pJP4-carrying cells from laboratory cultures, as well as from the rhizosphere of A. thaliana grown in natural soil. After co-inoculation of donor P. chlororaphis pJP4 and recipient Ralstonia eutropha, a combination of immunofluorescence and oligonucleotide hybridization techniques permitted the detection of plasmid transfer between both organisms in the A. thaliana rhizosphere. This strategy may be generally applicable for the analysis of plasmid transfer in natural ecosystems.

Plant-growth-promoting rhizobacteria (PGPRs) are used as inoculants for biofertilization, phytostimulation and biocontrol. The interactions of PGPRs with their biotic environment, for example with plants and microorganisms, are often complex. Substantial advances in elucidating the genetic basis of the beneficial effects of PGPRs on plants have been made, some from whole-genome sequencing projects. This progress will lead to a more efficient use of these strains and possibly to their improvement by genetic modification.

A Gram-negative bacterium (CRB5) was isolated from a chromium-contaminated site that was capable of reducing hexavalent chromium to an insoluble precipitate, thereby removing this toxic chromium species from solution. Analysis of the 16S rRNA from the isolate revealed that it was a pseudomonad with high similarity to Pseudomaonas synxantha. CRB5 was tolerant to high concentrations of chromate (500 mg l(-1)) and can reduce Cr(VI) under aerobic and anaerobic conditions. It also exhibited a broad range of reduction efficiencies under minimal nutrient conditions at temperatures between 4 degrees C and 37 degrees C and at pH levels from 4 to 9. As reduction increased, so did total cellular protein, indicating that cell growth was a requirement for reduction. Under low nutrient conditions with CRB5 or when using non-sterile contaminated groundwater from the site, reduction of Cr(VI) was followed by a increase in solution turbidity as a result of the formation of fine-grained Cr(III) precipitates, most probably chromium hydroxide mineral phases such as Cr(OH)3. Chromium adsorption and precipitation, as observed by transmission electron microscopy coupled with energy dispersive X-ray spectroscopy (TEM/EDS), revealed that the surfaces of the cells were uniformly stained with bound Cr(III) and amorphous precipitates (as determined by selected area electron diffraction; SAED). A mass balance of chromium in a batch bioreactor revealed that up to 30% of the total Cr was as settable precipitates or bound to cells.

A bacterial strain FP2001 isolated from the exudate of land reclaimed for municipal waste was identified as Pseudomonas paucimobilis. Cells of strain FP2001 were mobile by means of polar monotrichous flagellum, only when rhamnose was added as a carbon source in the liquid medium. The replacement of rhamnose by arabinose, galactose, glucose or xylose did not lead to the formation of flagella.

Arthrobacter globiformis and a Pseudomonas soil isolate were incubated separately and in combination in soil that had been presterilized by autoclaving. Growth and other responses of the cells in situ in this soil were monitored by plate counts and transmission electron microscopy examinations of cell sections. During the soil incubations, some of the samples were first allowed to dry and then were remoistened with water or with a dilute or a concentrated nutrient solution. Based on plate counts and ultrastructural analysis. Arthrobacter seemed to be in a non-multiplying coccoid-rod resting state and to be virtually immune to soil drying. Addition of a dilute nutrient solution helped maintain cell ultrastructure and prevent a low level of lysing that occurred in the absence of nutrient addition. Addition of a concentrated nutrient solution brought on cell multiplication as both coccoid-rods and long rods, but the ultimate form with further incubation was the coccoid-rod. The Pseudomonas strain suffered death and ultrastructural deterioration as water became less available. It responded by cell multiplication to an equal extent when either water or dilute nutrients were added, but possibly was able to give a growth response to nutritive amendment when a concentrated nutrient addition was made. The Arthrobacter was not affected by the presence of Pseudomonas in dual culture. The Pseudomonas, however, possibly suffered a nutritive deficiency under these conditions.