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4466

In January 2011, tomato (Solanum lycopersicum) plants exhibiting stunting, yellow mosaic, short, chlorotic leaves, aborted flowers, and reduced-size fruits, symptoms similar to those exhibited by plants infected by ‘Candidatus Liberibacter solanacearum’ (2), were observed in approximately 5% of tomato plants in greenhouses in Jocotitlan in the State of Mexico, Mexico. Occasional plant recovery was also observed. Tomato plants in this facility were previously shown to be infected by Mexican papita viroid (MPVd), Pepino mosaic virus (PepMV), and aster yellows phytoplasma. Eight symptomatic leaf samples (designated MX11-01 to MX11-08) were collected and screened against selected tomato viruses and pospiviroids by reverse transcription (RT)-PCR using purified plant RNA or for ‘Ca. L. solanacearum’ by PCR using purified plant DNA. As expected, both PepMV and MPVd were detected in these samples. However, two ‘Ca. L. solanacearum’-specific PCR products (1,168 and 669 bp) were also amplified in two samples (MX11-02 and MX11-05) using primers OA2 (2) and OI2c (1) or CL514F/CL514R (3), respectively. Each ‘Ca. L. solanacearum’-specific PCR product was gel purified with Geneclean (Q-Biogene, Carlsbad, CA) and cloned into pCR2.1 using TOPO TA cloning kit (Invitrogen, Carlsbad, CA) and sequenced (Functional Biosciences, Madison, WI). Sequences of 16S rRNA (1,168 bp) in both isolates (GenBank Accession Nos. JF811596 and JF811597) were identical. However, the 669-bp 50S rRNA sequences in these two isolates (GenBank Accession Nos. JF811598 and JF811599) contained two single nucleotide polymorphism (SNP) mutations. BLASTn searches showed that both 16S rRNA and 50S gene sequences in MX11-05 were identical to the ‘Ca. L. solanacearum’ previously identified on potato in Chihuahua (GenBank Accession Nos. FJ829811 and FJ829812) and Saltillo (GenBank Accession Nos. FJ498806 or FJ498807) in eastern Mexico. These ‘Ca. L. solanacearum’ isolates were recently classified as the “b” haplotype (4). Alignment analysis of the ‘Ca. L. solanacearum' 16S rRNA sequences also revealed the conserved SNP mutations (g.212T > G and g.581T > C) in MX11-02 and MX11-05 as previously identified for other “b” haplotype isolates (4). ‘Ca. L. solanacearum’ was first identified in greenhouse tomatoes in 2008 in New Zealand (2). It has also been identified in greenhouse and field tomatoes in the United States. ‘Ca. L. solanacearum’ was previously reported to infect field tomatoes in Sinaloa, Mexico (3), which was recently considered as the “a” haplotype (4). To our knowledge, this is the first report of ‘Ca. L. solanacearum’ naturally infecting tomatoes in Jocotitlan in the State of Mexico, Mexico. The greenhouse tomato ‘Ca. L. solanacearum’ may be transmitted from infected solanaceous plants by potato psyllids (Bactericera cockerelli), which were observed in this facility. References: (1) S. Jagoueix et al. Int. J. Syst. Bacteriol. 44:379, 1994. (2) L. W. Liefting et al. Plant Dis. 93:208, 2009. (3) J. E. Munyaneza et al. Plant Dis. 93:1076, 2009 (4) W. R. Nelson et al. Eur. J. Plant Pathol. 130:5, 2011.

The present study investigated the phylogenetic affiliation and physiological characteristics of bacteria responsible for anaerobic ammonium oxidization (anammox); these bacteria were enriched in an anammox reactor with a nitrogen removal rate of 26.0 kg N m−3day−1. The anammox bacteria were identified as representing ‘CandidatusBrocadia sinica’ on the basis of phylogenetic analysis of rRNA operon sequences. Physiological characteristics examined were growth rate, kinetics of ammonium oxidation and nitrite reduction, temperature, pH and inhibition of anammox. The maximum specific growth rate (μmax) was 0.0041 h−1, corresponding to a doubling time of 7 days. The half-saturation constants (Ks) for ammonium and nitrite of ‘Ca.B. sinica’ were 28±4 and 86±4 µM, respectively, higher than those of ‘CandidatusBrocadia anammoxidans’ and ‘CandidatusKuenenia stuttgartiensis’. The temperature and pH ranges of anammox activity were 25–45 °C and pH 6.5–8.8, respectively. Anammox activity was inhibited in the presence of nitrite (50 % inhibition at 16 mM), ethanol (91 % at 1 mM) and methanol (86 % at 1 mM). Anammox activities were 80 and 70 % of baseline in the presence of 20 mM phosphorus and 3 % salinity, respectively. The yield of biomass and dissolved organic carbon production in the culture supernatant were 0.062 and 0.005 mol C (molNH4+)−1, respectively. This study compared physiological differences between three anammox bacterial enrichment cultures to provide a better understanding of anammox niche specificity in natural and man-made ecosystems.

The taxonomic status of the families Actinosynnemataceae and Pseudonocardiaceae was assessed based on 16S rRNA gene sequence data available for the 151 taxa with validly published names, as well as chemotaxonomic and morphological properties available from the literature. 16S rRNA gene sequences for the type strains of all taxa within the suborder Pseudonocardineae were subjected to phylogenetic analyses using different algorithms in arb and phylip. The description of many new genera and species within the suborder Pseudonocardineae since the family Actinosynnemataceae was proposed in 2000 has resulted in a markedly different distribution of chemotaxonomic markers within the suborder from that observed at that time. For instance, it is noted that species of the genera Actinokineospora and Allokutzneria contain arabinose in whole-cell hydrolysates, which is not observed in the other genera within the Actinosynnemataceae, and that there are many genera within the family Pseudonocardiaceae as currently described that do not contain arabinose. Phylogenetic analyses of 16S rRNA gene sequences for all taxa within the suborder do not provide any statistical support for the family Actinosynnemataceae, nor are signature nucleotides found that support its continued differentiation from the family Pseudonocardiaceae. The description of the family Pseudonocardiaceae is therefore emended to include the genera previously classified within the family Actinosynnemataceae and the description of the suborder Pseudonocardineae is also emended to reflect this reclassification.