Publications

3826

Winter oilseed rape (Brassica napus L.) is widely grown in Poland to produce vegetable oil for industrial processing of human and animal feed. In recent years, according to European Union directives on the use of biofuels (Directive 2003/30/EC), the area under oilseed rape cultivation in Poland has dramatically increased to 810,000 ha in 2009 and is still increasing. Morphological deformations of winter oilseed rape indicative of phytoplasma infection have been observed sporadically in Poland since 2000 (3). Plants exhibiting floral virescence, phyllody, as well as auxiliary bud proliferation, reduced leaves, and malformation of siliques were identified during surveys of research fields in Wielkopolska during May and June of 2009 and 2010. To confirm phytoplasma infection of these plants, inflorescence and leaf tissues were collected from nine diseased and three symptomless plants from three different field locations with 1 to 16% disease incidence. Total DNA was extracted from each plant tissue sample with a modified cetyltrimethylammoniumbromide method (2). Samples were analyzed for phytoplasma DNA with a nested PCR assay employing phytoplasma universal rRNA operon primer pair P1/P7 followed by R16F2n/R16R2, using previously described conditions (1). PCR products of 1.8 and 1.2 kb were obtained from all diseased plants only following PCRs with P1/P7 and nested primer pair R16F2n/R16R2, respectively. PCR products were not obtained from symptomless plants. Eight 1.2-kb amplicons were sequenced (GenBank Accession Nos. JN193475 to JN193482). Comparative analysis of the R16F2n/R16R2 rDNA sequences confirmed the phytoplasma origin of the rDNA sequences that shared 100 to 99% identity with Maize bushy stunt phytoplasma (GenBank Accession No. HQ530152), Alfalfa stunt phytoplasma (GenBank Accession No. GU289675), Primula green yellows phytoplasma (GenBank Accession No. HM590623), and other aster yellows group phytoplasmas. A 1.8-kb amplicon of isolate designated RzW14 was sequenced (GenBank Accession No. HM561990) and had 99% identity with Aster yellow group phytoplasmas from Lithuania (GenBank Accession Nos.GU223208 and AY744071). A virtual restriction fragment length polymorphism analysis of the 16S rDNA sequences from the R16F2n/R16R2 amplicons was performed with iPhyClassifier (4). Restriction profile comparisons identified all aster yellows group phytoplasmas as subgroup 16SrI-B strains. To our knowledge, this is the first report of a ‘Candidatus Phytoplasma asteris’-related strain infecting oilseed rape in Poland. References: (1) I. M. Lee et al. Int. J. Syst. Bacteriol. 48:1153, 1998. (2) A. C. Padovan et al. Aust. J. Grape Wine Res. 1:25, 1995. (3) M. Starzycki and E. Starzycka. Oilseed Crops 21:399, 2000. (4) Y. Zhao et al. Int. J. Syst. Evol. Microbiol. 59:2582, 2009.

An aerobic, saccharolytic, obligately thermophilic, motile, non-spore-forming bacterium, strain T49T, was isolated from geothermally heated soil at Hell’s Gate, Tikitere, New Zealand. On the basis of 16S rRNA gene sequence similarity, T49T is the first representative of a new class in the newly described phylum Armatimonadetes, formerly known as candidate division OP10. Cells of strain T49T stained Gram-negative and were catalase-positive and oxidase-negative. Cells possessed a highly corrugated outer membrane. The major fatty acids were 16 : 0, i17 : 0 and ai17 : 0. The G+C content of the genomic DNA was 54.6 mol%. Strain T49T grew at 50–73 °C with an optimum temperature of 68 °C, and at pH 4.7–5.8 with an optimum growth pH of 5.3. A growth rate of 0.012 h−1 was observed under optimal temperature and pH conditions. The primary respiratory quinone was MK-8. Optimal growth was achieved in the absence of NaCl, although growth was observed at NaCl concentrations as high as 2 % (w/v). Strain T49T was able to utilize mono- and disaccharides such as cellobiose, lactose, mannose and glucose, as well as branched or amorphous polysaccharides such as starch, CM-cellulose, xylan and glycogen, but not highly linear polysaccharides such as crystalline cellulose or cotton. On the basis of its phylogenetic position and phenotypic characteristics, we propose that strain T49T represents a novel bacterial genus and species within the new class Chthonomonadetes classis nov. of the phylum Armatimonadetes. The type strain of Chthonomonas calidirosea gen. nov., sp. nov. is T49T ( = DSM 23976T = ICMP 18418T).

Incidence and severity of Huanglongbing (HLB) disease were assessed in Apr. 2010 among eight citrus cultivars representing diverse scion types growing in commercial groves in Florida's Indian River region, an area with a high incidence of HLB. In each grove, 20 trees of each cultivar were rated for visual HLB symptoms and leaves were collected for quantitative polymerase chain reaction quantification of Candidatus Liberibacter asiaticus (CLas), the presumptive causal agent of HLB. There was a strong correlation between HLB rating and CLas titer (titer represented by Ct, r2 = 0.37 and 0.40, for whole tree and leaf sample, respectively, both with P < 0.0001) across all cultivars and groves. Although incidence and severity of HLB varied considerably among the groves, scion-specific differences were apparent, even when analyses excluded potentially confounding grove effects. ‘Temple’ tangor showed the most consistently low incidence of HLB symptoms and CLas titer; in contrast, ‘Murcott’ tangor and ‘Minneola’ tangelo had the highest incidence of HLB symptoms and highest CLas titer. These results suggest useful resistance to HLB with reduced symptoms and reduced CLas titer may be found in conventional scion cultivars and further work is needed to assess this potential and its commercial value.

A sustainable option for nitrogen removal is the anaerobic ammonium-oxidizing (anammox) process in which ammonium is oxidized to nitrogen gas with nitrite as electron acceptor. Application of this process, however, is limited by the availability of anammox biomass. In this study, two Brocadia-like anammox phylotypes were successfully enriched, detected and identified from an activated sludge taken from a domestic wastewater treatment plant (Minas Gerais, Brazil) employing a Sequencing Batch Reactor (SBR). The dominant phylotype was closely related to ‘Candidatus Brocadia sinica’, but one clone seemed to represent a novel species for which we propose the name ‘Candidatus Brocadia brasiliensis’. Based on Fluorescence in situ hybridization (FISH) analysis, this enrichment led to a relative population size of 52.7% (±15.6) anammox bacteria after 6 months of cultivation. The cultivation process can be divided into three phases: phase 1 (approximately 25 days) was characterized by heterotrophic denitrification metabolism, phase 2 was the propagation phase and phase 3 (from the 87th day onwards), in which significant anammox activity was detected. A long-term performance of the SBR showed a near perfect removal of nitrite based on the influent NO2−-N concentration of 61–95 mg L−1. The average ammonia removal efficiency was 90% with the influent NH4+-N concentration of 55–82 mg L−1. Therefore, anammox cultivation and enrichment from activated sludge was possible under a controlled environment within 3 months.

ABSTRACT The sequence of the genome of “ Candidatus Tremblaya princeps” strain PCVAL, the primary endosymbiont of the citrus mealybug Planococcus citri , has been determined. “ Ca . Tremblaya princeps” presents an unusual nested endosymbiosis and harbors a gammaproteobacterial symbiont within its cytoplasm in all analyzed mealybugs. The genome sequence reveals that “ Ca . Tremblaya princeps” cannot be considered an independent organism but that the consortium with its gammaproteobacterial symbiotic associate represents a new composite living being.

ABSTRACT Ammonia-oxidizing archaea are ubiquitous microorganisms which play important roles in global nitrogen and carbon cycle on earth. Here we present the high-quality draft genome sequence of an ammonia-oxidizing archaeon, “ Candidatus Nitrosopumilus koreensis” MY1, that dominated an enrichment culture of a soil sample from the rhizosphere. Its genome contains genes for survival in the rhizosphere environment as well as those for carbon fixation and ammonium oxidation to nitrite.