Pseudoxanthomonas bacteria that drive deposit formation of wood extractives can be flocculated by cationic polyelectrolytes.

Runnability problems caused by suspended bacteria in water using industries, have, in contrast to biofilms, received little attention. We describe here that Pseudoxanthomonas taiwanensis, a wide-spread and abundant bacterium in paper machine water circuits, aggregated dispersions of wood extractives ("pitch") and resin acid, under conditions prevailing in machine water circuits (10(9) cfu ml(-1), pH 8, 45°C). The aggregates were large enough (up to 50 µm) so that they could be expected to clog wires and felts and to reduce dewatering of the fiber web. The Pseudoxanthomonas bacteria were negatively charged over a pH range of 3.2-10. Cationic polyelectrolytes of the types used as retention aids or fixatives to flocculate "anionic trash" in paper machines were effective in flocculating the Pseudoxanthomonas bacteria. The polyelectrolyte most effective for this purpose was of high molecular weight (7-8 × 10(6) g mol(-1)) and low charge density (1 meq g(-1)), whereas polyelectrolytes that effectively zeroed the electrophoretic mobility (i.e., neutralized the negative charge) of the bacterium were less effective in flocculating the bacteria. Based on the results, we concluded that the polyelectrolytes functioning by bridging mechanism, rather than by neutralization of the negative charge, may be useful as tools for reducing harmful deposits resulting from interaction of bacteria with wood extractives in warm water industry.

Thermomonas koreensis sp. nov., a mesophilic bacterium isolated from a ginseng field.

A Gram-negative, non-spore-forming, rod-shaped, motile bacterium, strain Ko06(T), was isolated from soil from a ginseng field in South Korea and was characterized in order to determine its taxonomic position. 16S rRNA gene sequence analysis revealed that strain Ko06(T) belongs to the Gammaproteobacteria, and the highest levels of sequence similarity were with Thermomonas brevis LMG 21746(T) (98.4 %), Thermomonas fusca LMG 21737(T) (97.7 %), Thermomonas haemolytica A50-7-3(T) (96.5 %) and Thermomonas hydrothermalis SGM-6(T) (95.8 %). Chemotaxonomic data revealed that strain Ko06(T) possesses ubiquinone Q-8 and that the predominant fatty acids are C(15 : 0) iso, C(11 : 0) iso and C(11 : 0) iso 3-OH, all of which corroborated assignment of the strain to the genus Thermomonas. The results of DNA-DNA hybridization and physiological and biochemical tests clearly demonstrated that strain Ko06(T) represents a distinct species. On the basis of these data, strain Ko06(T) (=KCTC 12540(T)=NBRC 101155(T)) should be classified as the type strain of a novel Thermomonas species, for which the name Thermomonas koreensis sp. nov. is proposed.

Pseudoxanthomonas kalamensis sp. nov., a novel gammaproteobacterium isolated from Johnston Atoll, North Pacific Ocean.

An aerobic, mesophilic bacterium, strain JA40T, was isolated from soil contaminated with polycyclic aromatic hydrocarbons and polychlorinated biphenyls collected from Johnston Atoll in the North Pacific Ocean. The strain formed yellow-pigmented colonies on heterotrophic media. The cells were Gram-negative, non-motile, non-sporulating rods. The strain reduced nitrite to nitrous oxide, the DNA G+C content was 64 mol% and the dominant fatty acids were 15 : 0 iso, 17 : 1 iso cis7 and 11 : 0 iso 3-OH. DNA sequencing of 1457 nt of the 16S rRNA gene established that JA40T belongs in the genus Pseudoxanthomonas within the Xanthomonadaceae branch of the Gammaproteobacteria. Strain JA40T can be differentiated from other mesophilic species in the genus on the basis of its physiological and biochemical characteristics and distinctive fatty acid profile. Thus strain JA40T (=ATCC BAA-1031T=CIP 108476T) is the type strain of a novel species of the genus Pseudoxanthomonas, for which the name Pseudoxanthomonas kalamensis sp. nov. is proposed.

Lysobacter concretionis sp. nov., isolated from anaerobic granules in an upflow anaerobic sludge blanket reactor.

The taxonomic positions of Lysobacter species with validly published names and a novel strain Ko07(T), which was newly isolated from an upflow anaerobic sludge blanket reactor treating wastewater from a brewery, were (re)estimated on the basis of results obtained by using a polyphasic taxonomy approach. Phylogenetic inference based on 16S rRNA gene sequences showed that strain Ko07(T) and all Lysobacter species with validly published names clustered together in a phylogenetic branch within the class 'Gammaproteobacteria'. The sequence similarity of strain Ko07(T) to the type strains of established Lysobacter species was in the range 94.9-96.7 %. Ubiquinone Q-8 and branched fatty acids, C(11 : 0) iso, C(15 : 0) iso, C(16 : 0) iso, iso C(17 : 1)omega9c and C(11 : 0) iso 3OH, predominantly appeared in strain Ko07(T) as well as in all type strains of the recognized Lysobacter species. The DNA-DNA hybridization values of strain Ko07(T) with those of recognized Lysobacter species were estimated to be 2-20 %. Despite sharing common taxonomic features in important phenotypic characteristics, such as gliding movement, long-rod shape and proteolytic activity, strain Ko07(T) could be distinguished from the Lysobacter species with validly published names by its low DNA-DNA hybridization value, a comparatively low DNA G + C content (63.8 mol%), substrate utilization and some physiochemical characteristics. On the basis of the results obtained in this study, it is proposed that strain Ko07(T) should be classified as representing a novel member of the genus Lysobacter, for which the name Lysobacter concretionis sp. nov. is proposed. The type strain is Ko07(T) (=KCTC 12205(T) = DSM 16239(T)).

Pseudoxanthomonas mexicana sp. nov. and Pseudoxanthomonas japonensis sp. nov., isolated from diverse environments, and emended descriptions of the genus Pseudoxanthomonas Finkmann et al. 2000 and of its type species.

Three mesophilic bacteria (strains AMX 26B(T), UR374_02 and 12-3(T)) isolated respectively from an anaerobic digester, human urine and urban riverside soil were characterized. Cells were Gram-negative, motile, non-sporulating, straight to curved rods with one polar flagellum and had a strictly respiratory metabolism with O(2) as the preferential terminal electron acceptor. Phylogenetic analysis based on 16S rRNA gene sequences revealed that all strains clustered within the Xanthomonadaceae branch of the Proteobacteria. Isolates AMX 26B(T) and UR374_02 exhibited 100 % 16S rRNA gene sequence similarity and both were related to strain 12-3(T) (99.6 % similarity). The closest relative of all the isolates was Pseudoxanthomonas broegbernensis DSM 12573(T) (similarity 97.1-97.5 %), and they were equidistantly related to Xanthomonas species (95.4-96.6 %), Stenotrophomonas species (95.3-96.1 %) and Pseudoxanthomonas taiwanensis ATCC BAA-4040(T) (95.3-95.4 %). Chemotaxonomic and biochemical data (branched-chain cellular fatty acid pattern without C(13 : 0) iso 3-OH, ubiquinone with eight isoprenoid units, limited range of substrates used, ability to reduce nitrite but not nitrate with the production of N(2)O) supported their affiliation to the genus Pseudoxanthomonas. The results of DNA-DNA hybridization and/or phenotypic analysis allowed them to be differentiated from the two Pseudoxanthomonas species with validly published names and showed that strain 12-3(T) was genomically and phenotypically distinct from the other two isolates. On the basis of these results, two novel species of the genus Pseudoxanthomonas are proposed: Pseudoxanthomonas mexicana sp. nov., consisting of strains AMX 26B(T) (=ATCC 700993(T)=CIP 106674(T)=JCM 11524(T)) (type strain) and UR374_02 (=DSM 15133), and Pseudoxanthomonas japonensis sp. nov., consisting of strain 12-3(T) (=CCUG 48231(T)=CIP 107388(T)=JCM 11525(T)). The report of these two novel species leads to the emendation of the description of the genus Pseudoxanthomonas and the re-evaluation of the phenotype of P. broegbernensis DSM 12573(T) necessitates the emendation of its description.

Hydrocarboniphaga effusa gen. nov., sp. nov., a novel member of the gamma-Proteobacteria active in alkane and aromatic hydrocarbon degradation.

Novel alkane-degrading strains of bacteria were isolated from soil contaminated with fuel oil from a leaking underground tank in New Jersey, USA. Two phenotypically similar strains (designated AP102 and AP103T) possessed 16S rRNA sequences unique among the majority of known hydrocarbon-degrading bacteria. The 16S rRNA sequences showed a moderate but distant relationship to the genus Nevskia and a substantial similarity to strains that had previously been isolated for growth on phenol (in Japan) and on toluene (in Canada) by other researchers. The hydrocarbon-degrading strains from Japan, Canada and New Jersey showed no resemblance to the typical morphology of Nevskia but did share a striking similarity among themselves in cell morphology, in the unusual appearance of colonies on various solid media and in various physiological properties. A full taxonomic analysis was performed, including DNA-DNA hybridization and nutritional screening with 117 organic compounds as sole sources of carbon and energy. The strains are active in the degradation of important environmental pollutants, and their phenotypic, physiological, metabolic and genomic properties suggest that they are members of a novel taxon in the gamma-Proteobacteria, for which the name Hydrocarboniphaga gen. nov. is proposed, with the single species Hydrocarboniphaga effusa sp. nov. The type strain is AP103T (=ATCC BAA-332T=DSM 16095T).

Distribution of Nevskia ramosa and other rosette-forming neustonic bacteria.

Samples from 27 natural and artificial aquatic environments were analyzed for the presence of rosette-forming bacteria by a combined cultivation and molecular biological approach. Rosette-forming bacteria developed in 20 enrichment cultures with ammonia-free medium under air. Three morphotypes could be distinguished. The most abundant type I resembled Nevskia ramosa and formed hydrophobic, flat, and dichotomously branching rosettes. Type II rosettes were three-dimensional and were observed in 10 enrichments, often together with those of type I. These rosettes were hydrophilic indicating life in the hyponeuston underneath the air-water interface. Rosettes of a third type consisted of hydrophilic slime stalks that were excreted at the cell poles and were observed in only one sample. Using fluorescence in situ hybridization (FISH) with the Nevskia-specific probes NEV177 and NEV656, the presence of Nevskia ramosa was demonstrated in exactly those samples that showed type I rosettes. In a series of most-probable-number experiments, during a calm and sunny weather period 430,000 Nevskia-like bacteria per mL were found in surface samples, while during rainy weather and within the water body the numbers were lower by several orders of magnitude. Five pure cultures isolated from various enrichments were characterized in detail. The two isolates forming type I rosettes were identified as Nevskia ramosa by 16S rDNA analysis. However, comparison by genomic fingerprinting (ERIC-PCR) revealed differences between the two isolates and previously characterized strains. The 16S rDNA of two isolates forming type II rosettes showed 97.6% similarity to that of Pseudomonas fluorescens. The closest relative of the isolate forming type III rosettes was Sphingomonas parapaucimobilis (96.4% sequence similarity of the 16S rRNA sequence). All isolates grew homogeneously submersed if ammonia was added to the medium. Our results indicate that Nevskia ramosa is a widely distributed epineustonic bacterium, which can specifically be deleted by its flat and hydrophobic rosettes on ammonia-free media.