Publications

4478

A novel slightly halophilic, aerobic, and Gram-stain-negative strain, designated as CH-27T, was isolated during a bacterial resource investigation of intertidal sediment collected from Xiaoshi Island in Weihai, PR China. Cells of strain CH-27T were rod-shaped with widths of 0.3–0.6 µm and lengths of 2.0–11.0 µm. Strain CH-27T grew optimally at 37 °C, pH 7.0 and with 2.0 % (w/v) NaCl. Catalase activity was weakly positive and oxidase activity was positive. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain CH-27T was most related to Marinihelvus fidelis KCTC 92639T (93.6 %), followed by Wenzhouxiangella marina MCCC 1K00261T (92.0 %). Based on genome comparisons between strain CH-27T and M. fidelis KCTC 92639T, the average amino acid identity was 63.6 % and the percentage of conserved proteins was 48.3 %. The major cellular fatty acid of strain CH-27T (≥10 %) was iso-C15 : 0 and the sole respiratory quinone was quinone-8. The polar lipids were phosphatidylglycerol, phosphatidylethanolamine, diphosphatidylglycerol, and aminophospholipid. The DNA G+C content was 62.7 mol%. Based on comprehensive analysis of its phylogenetic, physiological, biochemical, and chemotaxonomic characteristics, strain CH-27T represents a novel species in a novel genus, for which the name Elongatibacter sediminis gen. nov., sp.nov. is proposed. The type strain is CH-27T (=MCCC 1H00480T=KCTC 8011T).

The unculturable bacterium ‘ Candidatus Liberibacter solanacearum’ (CLso) is responsible for a growing number of emerging crop diseases. However, we know little about the diversity and ecology of CLso and its psyllid vectors outside of agricultural systems, which limits our ability to manage crop disease and understand the impacts this pathogen may have on wild plants in natural ecosystems. In North America, CLso is transmitted to crops by the native potato psyllid ( Bactericera cockerelli). However, the geographic and host plant range of the potato psyllid and CLso beyond the borders of agriculture are not well understood. A recent study of historic herbarium specimens revealed that a unique haplotype of CLso was present infecting populations of the native perennial Solanum umbelliferum in California decades before CLso was first detected in crops. We hypothesized that this haplotype and other potentially novel CLso variants are still present in S. umbelliferum populations. To test this, we surveyed populations of S. umbelliferum in Southern California for CLso and potato psyllid vectors. We found multiple haplotypes of CLso and the potato psyllid associated with these populations, with none of these genetic variants having been previously reported in California crops. These results suggest that CLso and its psyllid vectors are much more widespread and diverse in North American natural plant communities than suggested by data collected solely from crops and weeds in agricultural fields. Further characterization of these apparently asymptomatic haplotypes will facilitate comparison with disease-causing variants and provide insights into the continued emergence and spread of CLso.