A bacterial strain, designated AST4T, was isolated from activated sludge. The bacterium did not show significant growth on nutrient broth, but growth was clearly stimulated by addition of supernatant from other bacterial cultures. Culture filtrate of a strain related to the genus Sphingomonas in particular increased the cell yield and growth rate of strain AST4T. Phylogenetic analysis based on the 16S rRNA gene sequences showed that strain AST4T is located within the ‘Rhodobacter group’ in the α-3 subclass of Proteobacteria, but is clearly distant from related genera in this group such as Paracoccus, Rhodobacter and Rhodovulum. Strain AST4T is a Gram-negative, non-motile, rod-shaped (0·6–0·8×1·3–2·0 μm) and aerobic bacterium. It was not able to reduce nitrate to nitrite or N2. No phototrophic growth was observed. Optimal growth occurred at 30 °C and pH 6·5–7·5. The dominant cellular fatty acid in the isolate was C18 : 1 cis11. Ubiquinone-10 was the major respiratory quinone. The G+C content was 64·5 mol% (by HPLC). Based on the phylogenetic and phenotypic traits, the name Catellibacterium nectariphilum gen. nov., sp. nov. is proposed for this isolate; the type strain is AST4T (=NBRC 100046T=JCM 11959T=DSM 15620T).

No abstract

Potato scab is a serious plant disease caused by several Streptomyces sp., and effective control methods remain unavailable. Although antagonistic bacteria and phages against potato scab pathogens have been reported, to the best of our knowledge, there is no information about fungi that are antagonistic to the pathogens. The aim of this study was to isolate fungal antagonists, characterize their phylogenetic positions, determine their antagonistic activities against potato scab pathogens, and highlight their potential use as control agents under lower pH conditions. Fifteen fungal stains isolated from potato field soils were found to have antagonistic activity against three well-known potato scab pathogens: Streptomyces scabiei, Streptomyces acidiscabiei, and Streptomyces turgidiscabiei. These 15 fungal strains were phylogenetically classified into at least six orders and nine genera based on 18S rRNA gene sequencing analysis. These fungal isolates were related to members of the genera Penicillium, Eupenicillium, Chaetomium, Fusarium, Cladosporium, Mortierella, Kionochaeta, Pseudogymnoascus, and Lecythophora. The antagonistic activities of most of the fungal isolates were highly strengthened under the lower pH conditions, suggesting the advantage of combining their use with a traditional method such as soil acidification. This is the first report to demonstrate that phylogenetically diverse fungi show antagonistic activity against major potato scab pathogens. These fungal strains could be used as potential agents to control potato scab disease.

Flow cytometric sorting based on its large cell size enabled an enriched fraction of Oscillospira guillermondii cells to be obtained from the rumen contents of a sheep. Phylogenetic analysis based on cloned 16S rDNA sequences indicated that the bacterium is a member of the low-G+C Gram-positive bacterial cluster. Sporobacter termitidis and Papillibacter cinnamivorans were the most closely related known species, with sequence similarities of only 86?3-88?1 %. Fluorescently labelled 16S rRNA-targeted oligonucleotide probes specific for Oscillospira were designed and applied to the rumen sample from which the enriched fraction was obtained. The probes hybridized specifically with the large, morphologically conspicuous Oscillospira cells.Oscillospira guillermondii is a large bacterium (3-66 10-40 mm), often observed in the rumen contents of sheep and cattle as well as the alimentary tract of other herbivorous animals. Oscillospira is characterized as a Grampositive bacterium, with closely spaced transverse septa and endospores (Gibson, 1974(Gibson, , 1986Grain & Senaud, 1976;Stewart et al., 1997). Although this bacterium was first described almost a century ago (Chatton & Pérard, 1913), growth in pure culture has not been reported (Gibson, 1974(Gibson, , 1986Stewart et al., 1997), hence, little is known of its ecological role and physiological properties in the intestinal tract. Clarke (1979) found that Oscillospira and other large bacteria attached rapidly to the cuticular surface of clover and grass leaves in the rumen, suggesting that the cuticle of green leaves constitutes a specific niche for these bacteria. Warner (1966) investigated the relationship between grazing behaviour and changes in rumen microbial populations in sheep and found that the population of Oscillospira in the rumen fluctuated and the length of the trichome also changed depending upon the amount of feed consumed. Kurihara et al. (1968) reported that total counts of Oscillospira in the sheep rumen tended to decrease in the presence of ciliates. Although the number of Oscillospira cells is relatively small compared with other bacterial cells, they may make a significant contribution to rumen fermentation because of their large biomass, roughly equivalent to that of ruminal ciliate protozoa (Clarke, 1979;Williams & Coleman, 1997).To date, culture-based techniques have not enabled the phylogenetic relatedness of Oscillospira to known bacteria to be studied. Flow cytometry (FCM), a well-established technology in cell biology and medical microbiology, is now being applied to microbial ecology studies. FCM allows the rapid analysis of bacterial communities and enables single cells to be detected, quantified and sorted according to differences in size, DNA content or phylogenetic affiliation as assessed by fluorescently labelled rRNA-targeted oligonucleotide probes (Amann et al., 1990;Button et al., 1996;Davey & Kell, 1996;Jansson & Prosser, 1997;Wallner et al., 1997). Very recently, Zoetendal et al. (2002) have detected and enumerated uncultured R...

Key Words--effects of sodium acetate; lactate racemase; lactic acid bacteria; Lactobacillus coryniformis; Lactobacillus sakei; production of lactic acid; type of stereoisomers of lactic acid

We describe an application of gel microdroplet (GMD) and flow cytometry techniques to selective enrichment of non-growing Leuconostoc mesenteroides cells, which are well culturable on other media, from a mixture with Bacillus subtilis cells in nutrient broth. After encapsulating cells of the mixed population within GMDs and a brief incubation in nutrient broth, the inability of L. mesenteroides cells to form microcolonies within GMDs allowed their discrimination from B. subtilis cells. After staining the GMD mixture with 6-carboxyfluorescein diacetate, which showed no influence on cell viability, the GMDs containing single cells of L. mesenteroides were selectively collected using flow cytometry sorting based on differences in fluorescence intensity. The cells of L. mesenteroides retained viability during the process. ß

We describe an application of gel microdroplet (GMD) and flow cytometry techniques to selective enrichment of non-growing Leuconostoc mesenteroides cells, which are well culturable on other media, from a mixture with Bacillus subtilis cells in nutrient broth. After encapsulating cells of the mixed population within GMDs and a brief incubation in nutrient broth, the inability of L. mesenteroides cells to form microcolonies within GMDs allowed their discrimination from B. subtilis cells. After staining the GMD mixture with 6-carboxyfluorescein diacetate, which showed no influence on cell viability, the GMDs containing single cells of L. mesenteroides were selectively collected using flow cytometry sorting based on differences in fluorescence intensity. The cells of L. mesenteroides retained viability during the process.

Phosphate accumulating organisms (PAOs) stained with 4',6-diamidino-2-phenylindol dihydrochloride (DAPI) at polyphosphate probing concentration were sorted from enhanced biological phosphorus removal (EBPR) sludge by flow cytometric sorting. All the genome DNA was extracted from the sorted bacteria and the 16S rDNA genes were cloned. Cloned 16S rDNA was PCR-amplified and analyzed by restriction fragment length polymorphism (RFLP) analysis. Eighty eight clones were analyzed and the RFLP patterns which appeared more than twice were classified into seven groups. The most dominant group (Group 1) contained four clones and accounted for 4.5% of the total clones. Four groups (from Group 2 to Group 5) contained three clones. Group 6 and 7 consisted of two clones. Sixty-eight clones gave unique RFLP patterns. By sequencing 16S rDNA in seven groups, Group 1, 2 and 5 were Rhodocyclus relatives (11%, 10/88). Rhodocyclus relatives were suggested to be one of the bacteria responsible for EBPR in this sludge. Groups 6 and 7 were related to b- or g-Proteobacteria. Group 4 belonged to e-Proteobacteria. Group 3 was related to green nonsulfur bacteria. Considering the complex RFLP pattern and the existence of the groups not related to Rhodocyclus by sequence analysis, in this EBPR system, together with Rhodocyclus relatives, some other bacteria might also play a role as PAOs.