Genome Resource for Pseudomonas sp. Strain L22-9: A Potential Novel Species with Antifungal Activity.

Pseudomonas is a complex genus with increasing numbers of new species. Recently, we isolated Pseudomonas sp. strain L22-9, which showed antifungal activity against several fungal phytopathogens. Here, we report the whole genome sequence of strain L22-9. Genomic analysis revealed that strain L22-9 contains one circular DNA chromosome of 6,730,360 bp length with 60.9% GC content. Bioinformatics analysis identified gene clusters in the genome that synthesize antimicrobial metabolites such as 2,4-diacetylphloroglucinol synthesis and hydrogen cyanide synthase. Further analysis suggests that strain L22-9 is a novel species of the genus Pseudomonas. This genome would be a valuable resource for future research in phytopathology.

Pseudomonas bijieensis sp. nov., isolated from cornfield soil.

Strain L22-9T, a Gram-stain-negative and rod-shaped bacterium, motile by one polar flagellum, was isolated from cornfield soil in Bijie, Guizhou Province, PR China. Based on 16S rRNA gene sequences, it was identified as a Pseudomonas species. Multilocus sequence analysis of concatenated 16S rRNA, gyrB, rpoB and rpoD gene sequences showed that strain L22-9T formed a clearly separated branch, located in a cluster together with Pseudomonas brassicacearum LMG 21623T, Pseudomonas kilonensis DSM 13647T and Pseudomonas thivervalensis DSM 13194T. Whole-genome comparisons based on average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) confirmed that strain L22-9T should be classified as a novel species. It was most closely related to P. kilonensis DSM 13647T with ANI and dDDH values of 91.87 and 46.3 %, respectively. Phenotypic features that can distinguish strain L22-9T from P. kilonensis DSM 13647T are the assimilation ability of N-acetyl-d-glucosamine, poor activity of arginine dihydrolase and failure to ferment ribose and d-fucose. The predominant cellular fatty acids of strain L22-9T are C16 : 0, summed feature 3 (C16 : 1 ω6c and/or C16 : 1 ω7c) and summed feature 8 (C18 : 1 ω7c and/or C18 : 1 ω6c). The respiratory quinones consist of Q-9 and Q-8. The polar lipids are diphosphatidylglycerol, phosphatidylethanolamine, two unidentified phosphoglycolipids, two unidentified aminophospholipids and an unidentified glycolipid. Based on the evidence, we conclude that strain L22-9T represents a novel species, for which the name Pseudomonas bijieensis sp. nov. is proposed. The type strain is L22-9T (=CGMCC 1.18528T=LMG 31948T), with a DNA G+C content of 60.85 mol%.

A-to-I mRNA Editing in a Ferric Siderophore Receptor Improves Competition for Iron in Xanthomonas oryzae pv. oryzicola.

Iron is an essential element for the growth and survival of pathogenic bacteria; however, it is not fully understood how bacteria sense and respond to iron deficiency or excess. In this study, we show that xfeA in Xanthomonas oryzae pv. oryzicola senses extracytoplasmic iron and changes the hydrogen bonding network of ligand channel domains by adenosine-to-inosine (A-to-I) RNA editing. The frequency of A-to-I RNA editing during iron-deficient conditions increased by 76.87%, which facilitated the passage of iron through the XfeA outer membrane channel. When bacteria were subjected to high iron concentrations, the percentage of A-to-I editing in xfeA decreased, which reduced iron transport via XfeA. Furthermore, A-to-I RNA editing increased expression of multiple genes in the chemotaxis pathway, including methyl-accepting chemotaxis proteins (MCPs) that sense concentrations of exogenous ferrienterobactin (Fe-Ent) at the cytoplasmic membrane. A-to-I RNA editing helps X. oryzae pv. oryzicola move toward an iron-rich environment and supports our contention that editing in xfeA facilitates entry of a ferric siderophore. Overall, our results reveal a new signaling mechanism that bacteria use to adjust to iron concentrations. IMPORTANCE Adenosine-to-inosine (A-to-I) RNA editing, which is catalyzed by the adenosine deaminase RNA-specific family of enzymes, is a frequent posttranscriptional modification in metazoans. Research on A-to-I editing in bacteria is limited, and the importance of this editing is underestimated. In this study, we show that bacteria may use A-to-I editing as an alternative strategy to promote uptake of metabolic iron, and this form of editing can quickly and precisely modify RNA and subsequent protein sequences similar to an "on/off" switch. Thus, bacteria have the capacity to use a rapid switch-like mechanism to facilitate iron uptake and improve their competitiveness.