Publications

4783

A motile, rod-shaped and anaerobic strain WK13T was isolated from a secondary root canal infection of a human tooth. WK13T cells were Gram-stain-negative, catalase-positive and oxidase-negative. The major fatty acids (≥ 5.0%) were C16 : 0, C18 : 0, C16 : 1  ω7c, C18 : 1  ω9c and C18 : 2  ω6,9c. The DNA G+C content was 57.94 mol%. The major polar lipids were phosphatidylethanolamine, phosphatidylserine, diphosphatidylglycerol, phosphatidylcholine and lysophosphatidylcholine. There were no respiratory quinones detectable. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain WK13T belongs to the class Betaproteobacteria. WK13T showed a 93.6% and 93.5% 16S rRNA gene sequence similarity to the most closely related cultured species, Propionivibrio pelophilus strain DSM 12018T and Propionivibrio dicarboxylicus strain DSM 5885T, respectively. On the basis of physiological and biochemical data, the isolate is considered to represent a novel species of a new genus in the class Betaproteobacteria, for which we propose the name Dentiradicibacter hellwigii gen. nov., sp. nov. The type strain is WK13T (=DSM 112713T=NCTC 14938T).

This study describes a Gram-stain-negative, rod-shaped, facultatively anaerobic bacterial species isolated from the octocoral Litophyton sp. inhabiting the live coral aquarium at Oceanário de Lisboa in Portugal. Four strains, NE35, NE40T, NE41 and NE43, were classified into the genus Endozoicomonas by means of 16S rRNA gene and whole-genome sequence homologies. We then performed phylogenetic, phylogenomic and biochemical analyses to examine their novel species status within the Endozoicomonas genus, based on comparisons with the designated novel type strain NE40T. The closest 16S rRNA gene relatives to strain NE40T are Endozoicomonas montiporae CL-33T (98.2%), Endozoicomonas euniceicola EF212T (97.6%) and Endozoicomonas gorgoniicola PS125T (97.2%). The four strains show genome-wide average nucleotide identity scores above the species level cut-off (95%) with one another and below the cut-off with all Endozoicomonas type strains with publicly available genomes. Digital DNA–DNA hybridization further supported the classification of the strains as a novel species, showing values below 70% when compared with other Endozoicomonas type strains. The DNA G+C content of NE40T was 49.0 mol%, and its genome size was 5.45 Mb. Strain NE40T grows from 15 to 37 °C, with 1–5% (w/v) NaCl, and between pH 6.0 and 8.0 in marine broth and shows optimal growth at 28–32 °C, 2–3% NaCl and pH 7.0–8.0. The predominant cellular fatty acids are summed feature 3 (C16 : 1 ω6c and/or C16 : 1 ω7c), summed feature 8 (C18 : 1 ω6c and/or C18 : 1 ω7c), C16 :0 and C14 :0. Strain NE40T presents oxidase, catalase and β-galactosidase activities and can reduce nitrates to nitrites and degrade cellulose, chitin, agarose and xylan. Based on the polyphasic approach employed in this study, we propose the novel species name Endozoicomonas lisbonensis sp. nov. (type strain NE40T=DSM 118084T=UCCCB 212T).

Understanding the characteristics of microbes during long-term space missions is essential for safeguarding the health of astronauts and maintaining the functionality of spacecraft. In this study, a Gram-positive, aerobic, spore-forming, rod-shaped strain JL1B1071T was isolated from the surface of hardware on the China Space Station. This strain belongs to the genus Niallia, with its closest relative being Niallia circulans ATCC 4513T. The genome of JL1B1071T is 5 166 230 bp in size, with a G+C content of 35.6 mol%. The average nucleotide identity and digital DNA–DNA hybridization values between JL1B1071T and N. circulans ATCC 4513T are 83.3 and 27.5%, respectively, both below the recommended thresholds for species delineation. The major cellular fatty acids were anteiso-C15:0 and iso-C15:0. The major quinone was menaquinone-7 (MK-7). Notably, strain JL1B1071T demonstrates a unique ability to hydrolyse gelatin, suggesting that it can utilize gelatin as a substrate in nutrient-limited environments. Genomic analysis of JL1B1071T revealed two conserved signature indels in the GAF domain-containing protein and DNA ligase D protein, which are specific to the genus Niallia. Additionally, structural and functional differences in proteins BshB1 and SplA were identified, which may enhance biofilm formation, oxidative stress response and radiation damage repair, thereby aiding its survival in the space environment. Based on phenotypic, physiological and chemotaxonomic characteristics, as well as genome annotation, strain JL1B1071T was considered a novel species within the genus Niallia and is proposed to be named Niallia tiangongensis sp. nov. The type strain is JL1B1071T (=GDMCC 1.4642=KCTC 43715).

AbstractBACKGROUNDHuanglongbing (HLB) is a systemic disease of citrus caused by the bacterial pathogen Candidatus Liberibacter asiaticus (CLas) that limits citrus production worldwide. CLas is an obligate bacterial pathogen that multiplies in citrus trees and in the insect vector, the Asian citrus psyllid (ACP), Diaphorina citri Kuwayama. There is no cure for HLB currently and broad‐spectrum antibiotics represent one possible therapeutic against disease symptoms. Single‐stranded nucleic acid analogs, 2′‐deoxy‐2’‐Fluoro‐β‐D‐arabinonucleic antisense oligonucleotides (FANA ASOs), can modulate gene expression by enzymatic degradation or steric blocking of an RNA target. FANA ASOs recognize and bind to specific RNA forms, including mRNA, miRNA and long noncoding RNA, through complementary base‐pairing.RESULTSInjection of oxytetracycline (OTC) into mature citrus trees with HLB ameliorated symptoms of disease, increased fruit yield and quality of juice as compared with that produced by noninjected controls. Injection of trees with FANA ASOs reduced CLas abundance but did not improve fruit yield and quality above control levels at the injection dosage tested. Reduced pathogen relative abundance following OTC injection was coincident with lower CLas acquisition and inoculation by laboratory deployed and wild‐type D. citri collected from the field, respectively. However, injections of FANA ASOs did not consistently reduce CLas transmission as compared with noninjected controls.CONCLUSIONSTrunk injection of OTC may be useful in management of HLB by reducing CLas infection in trees and disrupting transmission. However, more research is needed to verify the potential usefulness of FANA ASOs. Optimizing FANA ASO dosage in trees and exploring the potential of multiplex FANA ASOs that simultaneously target multiple mRNAs could possibly enhance their efficacy against CLas. © 2024 Society of Chemical Industry.

AbstractBACKGROUNDHuanglongbing (HLB) is the primary and most destructive disease affecting citrus, caused by a pathogen transmitted by an insect vector, Diaphorina citri. There are no curative methods for the disease, and rapid and accurate methods are needed for early detection in the field, even before symptoms appear. These will facilitate the faster removal of infected trees, preventing the spread of the bacteria through commercial citrus orchards.RESULTSIt was possible to determine ranges of hyperspectral bands that demonstrated significant differences in relative reflectance between treatments consisting of healthy and infected plants from the first days of evaluation, when plants infected with ‘Candidatus Liberibacter asiaticus’ (CLas) were still in the asymptomatic stage of the disease. From the Week 2 of evaluation [58 days after infection (DAI) of plants] until the last week, spectral differences were detected in the red edge region (660–750 nm). From the Week 6 onwards (86 DAI), spectral differences between healthy and symptomatic plants were observed in bands close to the visible region (520–680 nm).CONCLUSIONSpectral differences were detected in the leaves of C. sinensis infected by CLas before the appearance of symptoms, making it feasible to use the hyperspectral sensor to monitor the disease. Our results indicate the need for future studies to validate the use of hyperspectral sensors for managing and detecting HLB in commercial citrus orchards, contributing to the integrated management of the disease. © 2024 Society of Chemical Industry.

Abstract In 2022, EFSA was mandated by the European Commission's Directorate‐General for Health and Food Safety (M‐2022‐00070) to provide technical assistance on the list of Union quarantine pests qualifying as priority pests, as specified in Article 6(2) of Regulation (EU) 2016/2031 on protective measures against plant pests. As part of Task C, EFSA conducted comprehensive expert knowledge elicitations for candidate priority pests on the lag period, rate of expansion and impact on production (yield and quality losses) and the environment. This report provides the rationale for the dataset on the three Candidatus Liberibacter species associated with citrus greening disease, delivered to the European Commission's Joint Research Centre, to feed into the Impact Indicator for Priority Pest (I2P2) model and complete the pest prioritisation ranking exercise.