Publications

4992

Resumen. Interpolación espacial de Candidatus Liberibacter asiaticus1 junto Con su vector Diaphorina citri2 en Tamaulipas, México: Un enfoque geoestadístico incorporando variables climáticas La producción de cítricos en Tamaulipas, México, se ha visto afectada por el Huanglongbing (HLB), una enfermedad de distribución global en árboles cítricos causada por la bacteria Candidatus Liberibacter asiaticus Jagoueix (CLas) (Hyphomicrobiales: Rhizobiaceae). Debido a la falta de tratamiento para el patógeno, los métodos de control se han centrado principalmente en su vector: el psílido asiático de los cítricos, Diaphorina citri Kuwayama (Hemiptera: Psyllidae), para combatirlo. Para apoyar y mejorar la vigilancia y el control de la propagación del HLB, este estudio empleó métodos geoestadísticos para modelar y predecir la distribución espacial continua de CLas. Empleamos Kriging Ordinario (KO) y CoKriging Ordinario (CKO) empleando covariables climáticas, temperatura media y máxima, precipitación y número de días lluviosos. La validación cruzada mostró que el modelo CKO que incorporo la precipitación (CKO -P) tuvo el mejor desempeño predictivo, seguidos por los que incluían temperatura media (CKO -Tmed) y máxima (CKO -Tmax), mientras que KO y CKO con días lluviosos (CKO -D) presentaron un rendimiento menos eficiente. Los mapas de interpolación identificaron a Güémez, Victoria y Padilla como los principales puntos críticos, coincidiendo con los grupos previamente reportados. Tula, Jiménez, Altamira, Abasolo y Soto la Marina fueron identificados como áreas climáticamente favorables fuera de la región tradicional de producción de cítricos y más allá de los grupos significativos. Estos resultados indican que la predicción de la ocurrencia de CLas y D. citri no depende solo de la proximidad a casos previamente registrados, sino que también puede mejorarse con la variabilidad ambiental. Esto amplía la información de las zonas de vigilancia, lo que puede fortalecer el monitoreo epidemiológico y el manejo regional del HLB en Tamaulipas y otras regiones.

The family Gallionellaceae includes neutrophilic, aerobic, iron-oxidizing bacteria, many of which remain uncultured and known only from metagenomic data. In this study, two high-quality Gallionellaceae genomes were assembled from a ferruginous spring in the Voronezh region, Russia. Phylogenetic analysis based on 120 concatenated proteins, ANI (average nucleotide identity), and AAI (average amino acid identity) indicates that BG-057 belongs to the genus Gallionella and BG-364 to the genus 39-52-133. We propose the names “Candidatus Gallionella aquifuscii” sp. nov. for BG-057 and “Candidatus Dubininella ochracea” gen. nov., sp. nov. for BG-364. Both genomes encode genes for the Calvin-Benson-Bassham (CBB) cycle. Both are potentially capable of aerobic respiration due to the presence of electron transfer chain components. Both genomes encode the iron oxidase Cyc2, and BG-057 also encodes MtoA. BG-057 is potentially capable of lithotrophic growth in the presence of H2 and H2S. BG-364 is potentially capable of growth via Mn (II) oxidation; arsenite oxidation; the direct oxidation of thiosulfate; H2S, elemental sulfur, and sulfite oxidation. BG-364 encodes denitrification genes (narGHI, nirS, norBC). BG-057 possesses systems for the biosynthesis and export of siderophores, while BG-364 lacks these systems but retains Ton-dependent receptors, suggesting the use of exogenous siderophores.

ABSTRACT The recovery of partial nitritation and anammox (PN/A) process after starvation remains challenging. Substrate limitation disrupts microbial activity and delays the restoration of nitrogen removal performance. Therefore, PN/A nitrogen removal performance was evaluated in a 20‐L laboratory‐scale continuous stirred‐tank reactor (CSTR) containing sponge carriers across four operational phases. The four phases included 3‐month starvation, gradual substrate reintroduction under suspended‐growth conditions, transitional stabilization with sponge media, and attached‐growth recovery under higher nitrogen loading without external acetate supplementation. The laboratory reactor was operated at a nitrogen loading rate of 0.4–0.7 kg N/(m 3 ·d), dissolved oxygen below 0.1 mg/L, and without organic carbon addition. The nitrogen removal efficiency, microbial community composition, and microbial markers of the laboratory‐scale reactor were compared with those of two well‐operated full‐scale systems in Korea and the United States. Total nitrogen removal efficiency exceeded 90% across all three systems when the ammonia‐to‐nitrite ratio (NH₄ + :NO 2 − ) was maintained between 1:1 and 1:1.5 at low BOD/TN ratio of < 0.05. Next‐generation sequencing (Illumina MiSeq, 16S rRNA amplicon profiling at a sequencing depth of 41,120–57,097 reads/sample) was employed to determine the relative abundance of nitrogen‐transforming microbial communities, specifically the anammox group, across the three systems. The results showed that the anammox bacteria in all three systems belonged to Candidatus Brocadia. Following gene‐specific PCR amplification of the anammox community, denaturing gradient gel electrophoresis (DGGE) identified Candidatus Brocadia fulgida. This species exhibits high environmental adaptability and is commonly detected in full‐scale systems operated for > 5 years. Molecular analysis indicated that Candidatus Brocadia fulgida persisted in the system throughout the 3‐month starvation period, facilitating the re‐establishment of the attached‐growth PN/A process. The successful recovery of the laboratory‐scale reactor yielded nitrogen removal performance comparable to that of the full‐scale PN/A systems, demonstrating that the Brocadia group serves as a keystone taxon during process recovery.

‘ Candidatus Sarcina troglodytae’ (‘ Ca . S. troglodytae’), a proposed bacterial species in the family Clostridiaceae , has been epidemiologically associated with a lethal disease in sanctuary chimpanzees in Sierra Leone, epizootic neurologic and gastroenteric syndrome (ENGS). As sarcinae are known to be difficult to culture, a lack of viable in vitro growth conditions has limited further characterization of this bacterium. Such studies are critical to elucidating the relationship between ‘ Ca . S. troglodytae’ and ENGS. Here, we isolate a Gram-stain-positive, endospore-forming coccus and anaerobic bacterial strain, designated JB3 T , from brain tissue of a western chimpanzee ( Pan troglodytes verus ) using a reinforced clostridial medium. We describe the growth of strain JB3 T at a pH range of 6 to 9 (optimum 6) at 37 °C in an atmosphere composed of 5% H 2 , 5% CO 2 and 90% N 2 and demonstrate endospore production under alkaline conditions, suggesting the possibility of an environmental reservoir. We identify ethanol as the primary non-gaseous fermentation byproduct which we hypothesize to have relevance for ENGS. Antibiotic susceptibility testing shows susceptibility to common antimicrobial agents with notable resistance to ceftriaxone. By establishing in vitro conditions for the viable culture, propagation and storage of ‘ Ca . S. troglodytae’, this study lays the groundwork for future infection studies to test hypotheses about pathogenic mechanisms and prevention/treatment measures for ENGS.

Abstract The archaeal symbiotic Nanobdellales have been isolated with their hosts from a shallow hot marine vent off Iceland and from terrestrial hot springs in Yellowstone National Park and Japan. They have highly reduced genomes and rely on their archaeal hosts for most of their metabolic needs. Here, to provide further insights into the ecology and evolution of this order, we greatly expand their phylogenomic distribution using metagenome assembled genomes from deep-sea hydrothermal vents in the Atlantic, Pacific and Indian Oceans, and the Gulf of California. We show that at least 11 novel genus-level lineages occur at deep-sea vents. We conservatively propose two new genera with their nomenclatural types, Nanoprofundum liuii Rb-1Ts gen. nov. sp. nov. and Nanojejuna irisiana Rb-38Ts gen. nov. sp. nov. We also describe a second species of Nanoarchaeum, N. abyssimaris 17S-22Ts sp. nov. Our genomic and metabolic characterisation of the high-quality metagenome-assembled genomes confirm their highly reduced metabolic capabilities and likely symbiotic lifestyle. With the exception of Nanoarchaeum, all deep-sea genera resemble their terrestrial relatives in that they have genes that encode for archaella and RNAase P protein subunits, and have several genes involved in glycolysis and gluconeogenesis. Using an inferred lateral gene transfer analysis, our data suggest that deep-sea Nanobdellales may potentially associate with a greater taxonomic breadth of hosts than previously reported, spanning members of the Sulfolobales (Ignicoccaceae), the Archaeoglobales and Methanococcales.

SUMMARY The ubiquitin proteasome system (UPS) and autophagy cooperatively orchestrate plant immune homeostasis, while diverse phytopathogens deploy secreted effectors to disrupt their crosstalk for successful colonization. Proteaphagy, the autophagic turnover of intact 26S proteasome holoenzymes, is a conserved stress response co‐opted by Pseudomonas syringae effector HopM1 to cripple host proteolysis. However, how the Huanglongbing (HLB) pathogen ‘ Candidatus Liberibacter asiaticus’ ( C Las) simultaneously manipulates UPS and autophagy to subvert citrus immunity remains largely uncharacterized. Here, we functionally characterize the secreted C Las effector SDE5640, which exacerbates HLB susceptibility in sweet orange ( Citrus sinensis ). SDE5640 directly binds the 19S proteasome chaperone CsPSMD10, whose homodimerization via Cys163/Cys190 disulfide bonds is required for immune suppression. CsPSMD10 overexpression enhances citrus susceptibility to C Las, whereas the dimerization‐deficient CsPSMD10‐C190S mutant confers robust HLB resistance. Mechanistically, CsPSMD10 targets CsATG8 isoforms for UPS‐dependent degradation to restrain autophagic flux; SDE5640 competitively occupies the Ank2/Ank3 domains of CsPSMD10 to disrupt CsPSMD10‐CsATG8c complexes, thereby stabilizing CsATG8c and triggering autophagy dependent on CsPSMD10. Moreover, SDE5640‐induced autophagy drives selective autophagic degradation of the 20S proteasome catalytic subunit CsPBA1, which ultimately disrupts cellular proteasome activity and attenuates salicylic acid‐mediated citrus immunity. Collectively, our findings identify a novel SDE5640‐CsPSMD10‐CsATG8c‐CsPBA1 regulatory cascade, illustrating how a single C Las effector synchronously rewires the UPS‐autophagy crosstalk to facilitate pathogen proliferation.