Use of molecular and isotopic techniques to monitor the response of autotrophic ammonia-oxidizing populations of the beta subdivision of the class proteobacteria in arable soils to nitrogen fertilizer.
(1/369)
This study examined the effects of NH(4)NO(3) fertilizer on the size and activity of nitrifying, autotrophic, ammonia-oxidizing populations of the beta subdivision of the class Proteobacteria in arable soils. Plots under different long-term fertilizer regimes were sampled before and after NH(4)NO(3) additions, and the rates of nitrification were determined by (15)N isotopic pool dilution assays. Ammonia-oxidizing populations in the plots were quantified by competitive PCR assays based on the amoA and ribosomal 16S genes. Prior to fertilizer addition, ammonium concentrations and nitrification rates in the plots were comparatively low; ammonia-oxidizing populations were present at 10(4) to 10(5) gene copies g of soil(-1). Three days after the application of fertilizer, nitrification rates had risen considerably but the size of the ammonia-oxidizing population was unchanged. Six weeks after fertilizer treatment, ammonium concentrations and nitrification rates had fallen while the ammonia-oxidizing populations in plots receiving fertilizer had increased. The rapidity of the rise in nitrification rates observed after 3 days suggests that it results from phenotypic changes in the ammonia-oxidizing bacterial population. Associated increases in population sizes were only observed after 6 weeks and did not correlate directly with nitrifying activity. Phylogenetic analyses of PCR products from one of the plots revealed a population dominated by Nitrosospira-type organisms, similar to those prevalent in other soils. (+info)
Purification, characterization, and gene analysis of a chitosanase (ChoA) from Matsuebacter chitosanotabidus 3001.
(2/369)
The extracellular chitosanase (34,000 M(r)) produced by a novel gram-negative bacterium Matsuebacter chitosanotabidus 3001 was purified. The optimal pH of this chitosanase was 4.0, and the optimal temperature was between 30 and 40 degrees C. The purified chitosanase was most active on 90% deacetylated colloidal chitosan and glycol chitosan, both of which were hydrolyzed in an endosplitting manner, but this did not hydrolyze chitin, cellulose, or their derivatives. Among potential inhibitors, the purified chitosanase was only inhibited by Ag(+). Internal amino acid sequences of the purified chitosanase were obtained. A PCR fragment corresponding to one of these amino acid sequences was then used to screen a genomic library for the entire choA gene encoding chitosanase. Sequencing of the choA gene revealed an open reading frame encoding a 391-amino-acid protein. The N-terminal amino acid sequence had an excretion signal, but the sequence did not show any significant homology to other proteins, including known chitosanases. The 80-amino-acid excretion signal of ChoA fused to green fluorescent protein was functional in Escherichia coli. Taken together, these results suggest that we have identified a novel, previously unreported chitosanase. (+info)
Janthinobacterium agaricidamnosum sp. nov., a soft rot pathogen of Agaricus bisporus.
(3/369)
A novel bacterium has been found that causes a soft rot disease of Agaricus bisporus, the cultivated mushroom. It has been characterized using nutritional, physiological, chemical and molecular techniques. Based on these data, it was shown to have many characteristics in common with members of the genus Janthinobacterium. Despite similarities to the only described species within this genus, Janthinobacterium lividum, there were a number of differences between the mushroom pathogen isolated and this species. Despite the high degree of genotypic similarity between members of the genus Janthinobacterium and Herbaspirillum, as evidenced by DNA-RNA hybridization, and the high degree of 16S rDNA sequence similarity between members of the genera Janthinobacterium, Herbaspirillum, Oxalobacter and Duganella, as well as the generically misnamed Pseudomonas lemoignei, it was possible to show that members of the genus Janthinobacterium could be easily distinguished from these taxa. The data also indicated that the mushroom pathogenic strains represent a novel species within the genus Janthinobacterium for which the name Janthinobacterium agaricidamnosum sp. nov. is proposed. The type strain of this species has been deposited in the Deutsche Sammlung von Mikroorganismen und Zellkulturen GmbH, Braunschweig, Germany, as DSM 9628T and at the National Collection of Plant-pathogenic bacteria, UK, as NCPPB 3945T. To aid practical control of the disease, the effect of the relative humidity on symptom expression on Agaricus bisporus was determined. (+info)
Endosymbiotic microbiota of the bamboo pseudococcid Antonina crawii (Insecta, Homoptera).
(4/369)
We characterized the intracellular symbiotic microbiota of the bamboo pseudococcid Antonina crawii by performing a molecular phylogenetic analysis in combination with in situ hybridization. Almost the entire length of the bacterial 16S rRNA gene was amplified and cloned from A. crawii whole DNA. Restriction fragment length polymorphism analysis revealed that the clones obtained included three distinct types of sequences. Nucleotide sequences of the three types were determined and subjected to a molecular phylogenetic analysis. The first sequence was a member of the gamma subdivision of the division Proteobacteria (gamma-Proteobacteria) to which no sequences in the database were closely related, although the sequences of endosymbionts of other homopterans, such as psyllids and aphids, were distantly related. The second sequence was a beta-Proteobacteria sequence and formed a monophyletic group with the sequences of endosymbionts from other pseudococcids. The third sequence exhibited a high level of similarity to sequences of Spiroplasma spp. from ladybird beetles and a tick. Localization of the endosymbionts was determined by using tissue sections of A. crawii and in situ hybridization with specific oligonucleotide probes. The gamma- and beta-Proteobacteria symbionts were packed in the cytoplasm of the same mycetocytes (or bacteriocytes) and formed a large mycetome (or bacteriome) in the abdomen. The spiroplasma symbionts were also present intracellularly in various tissues at a low density. We observed that the anterior poles of developing eggs in the ovaries were infected by the gamma- and beta-Proteobacteria symbionts in a systematic way, which ensured vertical transmission. Five representative pseudococcids were examined by performing diagnostic PCR experiments with specific primers; the beta-Proteobacteria symbiont was detected in all five pseudococcids, the gamma-Proteobacteria symbiont was found in three, and the spiroplasma symbiont was detected only in A. crawii. (+info)
Identification of polyphosphate-accumulating organisms and design of 16S rRNA-directed probes for their detection and quantitation.
(5/369)
Laboratory-scale sequencing batch reactors (SBRs) as models for activated sludge processes were used to study enhanced biological phosphorus removal (EBPR) from wastewater. Enrichment for polyphosphate-accumulating organisms (PAOs) was achieved essentially by increasing the phosphorus concentration in the influent to the SBRs. Fluorescence in situ hybridization (FISH) using domain-, division-, and subdivision-level probes was used to assess the proportions of microorganisms in the sludges. The A sludge, a high-performance P-removing sludge containing 15.1% P in the biomass, was comprised of large clusters of polyphosphate-containing coccobacilli. By FISH, >80% of the A sludge bacteria were beta-2 Proteobacteria arranged in clusters of coccobacilli, strongly suggesting that this group contains a PAO responsible for EBPR. The second dominant group in the A sludge was the Actinobacteria. Clone libraries of PCR-amplified bacterial 16S rRNA genes from three high-performance P-removing sludges were prepared, and clones belonging to the beta-2 Proteobacteria were fully sequenced. A distinctive group of clones (sharing >/=98% sequence identity) related to Rhodocyclus spp. (94 to 97% identity) and Propionibacter pelophilus (95 to 96% identity) was identified as the most likely candidate PAOs. Three probes specific for the highly related candidate PAO group were designed from the sequence data. All three probes specifically bound to the morphologically distinctive clusters of PAOs in the A sludge, exactly coinciding with the beta-2 Proteobacteria probe. Sequential FISH and polyphosphate staining of EBPR sludges clearly demonstrated that PAO probe-binding cells contained polyphosphate. Subsequent PAO probe analyses of a number of sludges with various P removal capacities indicated a strong positive correlation between P removal from the wastewater as determined by sludge P content and number of PAO probe-binding cells. We conclude therefore that an important group of PAOs in EBPR sludges are bacteria closely related to Rhodocyclus and Propionibacter. (+info)
Confirmation of Thiobacillus denitrificans as a species of the genus Thiobacillus, in the beta-subclass of the Proteobacteria, with strain NCIMB 9548 as the type strain.
(6/369)
Thiobacillus denitrificans is physiologically similar to the type species of the genus Thiobacillus, Thiobacillus Thioparus, and both are located in the beta-subclass of the Proteobacteria. T. denitrificans is distinguished from all other Thiobacillus species by its ability to grow as a facultatively anaerobic chemolithotroph, coupling the oxidation of inorganic sulfur compounds to the reduction of nitrate, nitrite and other oxidized nitrogen compounds to dinitrogen. A definitive description of this species is provided and strain NCIMB 9548T is designated as the type strain of the species, thereby correcting an earlier error in the literature. (+info)
Tepidimonas ignava gen. nov., sp. nov., a new chemolithoheterotrophic and slightly thermophilic member of the beta-Proteobacteria.
(7/369)
A bacterial isolate with an optimum growth temperature of about 55 degrees C was recovered on a medium composed of one part Kligler's iron agar and four parts of Thermus Agar from the host spring at Sao Pedro do Sul in central Portugal. Phylogenetic analyses using the 16S rRNA gene sequence of strain SPS-1037T indicated that the new organism represented a new genus and species of beta-Proteobacteria. The major fatty acids of strain SPS-1037T are C16:0 and C17:0. Ubiquinone 8 is the major respiratory quinone, and the major polar lipids are phosphatidylethanolamine and phosphatidylglycerol. The new isolate is aerobic and chemolithoheterotrophic. Thiosulfate and tetrathionate were oxidized to sulfate. The growth yield of the organism was improved by the addition of thiosulfate to media containing organic carbon sources, but the organism did not grow autotrophically under the conditions examined. Heterotrophic growth of strain SPS-1037T occurs on amino acids and organic acids, but this organism does not assimilate carbohydrates. On the basis of the phylogenetic analyses, and physiological and biochemical characteristics, it is proposed that strain SPS-1037T represents a new genus and a new species for which the name Tepidimonas ignava is proposed. (+info)
Description of Pandoraea gen. nov. with Pandoraea apista sp. nov., Pandoraea pulmonicola sp. nov., Pandoraea pnomenusa sp. nov., Pandoraea sputorum sp. nov. and Pandoraea norimbergensis comb. nov.
(8/369)
A polyphasic taxonomic study was performed on a group of isolates tentatively identified as Burkholderia cepacia, Ralstonia pickettii or Ralstonia paucula (formerly known as CDC group IVc-2). The isolates were mainly cultured from sputum of cystic fibrosis patients or from soil. SDS-PAGE of whole-cell proteins and AFLP fingerprinting distinguished at least five different species, and this was confirmed by DNA-DNA hybridizations. 16S rDNA sequence analysis of representative strains indicated that these organisms belong to the beta-subclass of the Proteobacteria, with the genera Burkholderia and Ralstonia as closest neighbours. Based on genotypic and phenotypic characteristics, the organisms were classified in a novel genus, Pandoraea. The DNA base composition of the members of the new genus is between 61.2 and 64.3 mol%. This novel genus includes four new species, Pandoraea apista (the type species) (type strain is LMG 16407T), Pandoraea pulmonicola (type strain is LMG 18106T), Pandoraea pnomenusa (type strain is LMG 18087T) and Pandoraea sputorum (type strain is LMG 18819T), and Pandoraea norimbergensis (Wittke et al. 1997) comb. nov. (type strain is LMG 18379T). The available clinical data indicate that at least some of these organisms may cause chronic infection in, and can be transmitted amongst, cystic fibrosis patients. (+info)