Publications

4381

Abstract Background: Ehrlichia is a genus of Rickettsiales bacteria closely related to human/animal disease and it plays an important role in public health. Naturally they are hosted by mammals such as canines, bovines, wild rodents and vectored by ticks. Results: In this study, we collected 121 rodent samples including 67 Niviventer fulvescens, 27 Rattus tanezumi, 24 Chiromyscus sp., 2 Rattus nitidus and 1 Leopoldamys edwardsi from Hainan province, which consists of the second largest island in China. The presence and genetic diversity of Ehrlichia was evaluated and characterized by amplifying and sequencing the 16S rRNA, groEL and gltA genes. An Ehrlichia species was detected in 5 of the 67 Niviventer fulvescens samples (7.46%). The 16S rRNA, groEL and gltA genes show highest 99.20%, 89.87% and 83.86% identity to known Ehrlichia sequences. In the phylogenetic trees they form a distinct cluster from any other species. Conclusions: We propose that this species present a putative novel Ehrlichia species nominated as ‘Candidatus Ehrlichia hainanensis’. Its pathogenicity to human is still to be further researched and molecular surveillance in local populations is needed.

Abstract Background Huanglongbing (HLB) is a major botanical pandemic of citrus crops caused by Candidatus Liberibacter asiaticus (Clas). It is important to understand the different mechanisms involved in interaction of pathogen with plants to develop novel management strategy against HLB. However, until now there has been no control strategy to manage this disease in vitro and on large scale in citrus grove. We found that, indigenous endophyte Bacillus subtilis L1-21, a patented strain isolated from healthy citrus tree, may have the potential to reduce the impact of pathogen through restructuring of core endophytes. Results A novel half-leaf method was developed to test the efficacy of B. subtilis L1-21 against Clas. Concentration of B. subtilis L1-21 at 104 cfu ml− 1 resulted in a 1000-fold reduction in Clas copy densities per gram of leaf midrib (107 to 104) by 4 d after treatment. With endophytes, where HLB incidence was reduced to < 3% and Clas copy density was reduced from 109 to 104 pathogen g− 1 of diseased leaf midrib. We found that 16 of 93 tree samples became Clas-free and functional pathways and pathogen resistance genes were regulated in diseased citrus trees after treatment. Conclusions This is the first large-scale study using an indigenous endophyte and shows its potential utility in sustainable disease management through strengthening the citrus microbiome.

Abstract Me.tha.no.tri.cha.ce'ae. N.L. fem. n. Methanothrix type genus of the family; suff. – aceae ending to denote a family; N.L. fem. pl. n. Methanotrichaceae the Methanothrix family. Sheathed, rod‐shaped cells with flat ends, usually 0.8–1.3 μm wide by 2.0–6.0 μm long. Nonmotile. Gram‐stain‐negative. Oxygen‐tolerant anaerobe. Slow‐growing organotrophic, splitting acetate into methane and CO 2 for energy generation. Some strains split formate into hydrogen and CO 2 without generating methane. CO 2 can be reduced into methane when cocultured with electrogenic Geobacter spp. via direct interspecies electron transfer (DIET). Lipids contain myo ‐inositol, ethanolamine, and galactose as the polar head groups. Genome sequences have been determined for all described species. Habitats : Widely distributed in anaerobic river mud, paddy field soil, hot springs, thermal lakes, thermophilic and mesophilic anaerobic wastewater digestors treating domestic wastes, granular sludge, anaerobic fixed‐bed reactors, and other types of anaerobic systems. DNA G + C content (mol%) : 51–61 (Genome). Type genus : Methanothrix Huser et al. 1982, VL10. Taxonomic and Nomenclature Notes According to the List of Prokaryotic names with Standing in Nomenclature (LPSN), the taxonomic status of the family Methanotrichaceae is: correct name (last update, February 2025) * . LPSN classification: Archaea / Methanobacteriati / Methanobacteriota / Methanosarcinia / Methanosarcinales / Methanotrichaceae The family Methanotrichaceae can also be recovered in the Genome Taxonomy Database (GTDB) as f__Methanotrichaceae (version v220) ** . GTDB classification: d__Archaea / p__Halobacteriota / c__Methanosarcinia / o__Methanotrichales / f__Methanotrichaceae * Meier‐Kolthoff et al. ( 2022 ). Nucleic Acids Res , 50 , D801 – D807 ; DOI: 10.1093/nar/gkab902 ** Parks et al. ( 2022 ). Nucleic Acids Res , 50 , D785 – D794 ; DOI: 10.1093/nar/gkab776

Abstract Me.tha'no.thrix. N.L. neut. n. methanum methane; Gr. fem. n. thrix , hair; N.L. fem. n. Methanothrix , methane (‐producing) hair. Straight, rod‐shaped cells with flat ends, usually 0.8–1.3 μm wide by 2.0–6.0 μm long enclosed in a tubular sheath. Forms short (∼5–25 μm) to long (>150 μm) flexible chains of cells within the sheath. Nonmotile. Gram‐stain‐negative. Lipids contain myo ‐inositol, ethanolamine, and galactose as the polar head groups. Oxygen‐tolerant anaerobe. Organotrophic, splitting acetate into methane and CO 2 for energy generation. Some strains split formate into H 2 and CO 2 without producing methane. CO 2 can be reduced to methane in coculture with Geobacter spp. via direct interspecies electron transfer (DIET). Growth factors such as vitamins are stimulatory. Yeast extract is required, stimulatory or inhibitory, depending on the strain. NaCl is not required for growth. Optimal temperatures range from 34 to 37°C for mesophilic strains and 55 to 60°C for thermophilic strains; optimal pH range is 7.0–7.8. Gas vacuoles are generally found in thermophilic strains. Occur in both mesophilic and thermophilic anaerobic sludge digesters as well as anaerobic sediments. Synonymous with the genus Methanosaeta . DNA G + C content (mol%) : 51–61 (genome). Type species : Methanothrix soehngenii Huser et al. 1982, VL10. Taxonomic and Nomenclature Notes According to the List of Prokaryotic names with Standing in Nomenclature (LPSN), the taxonomic status of the genus Methanothrix is: correct name (last update, February 2025) * . LPSN classification: Archaea / Methanobacteriati / Methanobacteriota / Methanosarcinia / Methanosarcinales / Methanotrichaceae / Methanothrix The genus Methanothrix can also be recovered in the Genome Taxonomy Database (GTDB) as g__Methanothrix (version v220) ** . GTDB classification: d__Archaea / p__Halobacteriota / c__Methanosarcinia / o__Methanotrichales / f__Methanotrichaceae / g__Methanothrix * Meier‐Kolthoff et al. ( 2022 ). Nucleic Acids Res , 50 , D801 – D807 ; DOI: 10.1093/nar/gkab902 ** Parks et al. ( 2022 ). Nucleic Acids Res , 50 , D785 – D794 ; DOI: 10.1093/nar/gkab776