Pasteurella multocida strains of a novel capsular serotype and lethal to Marmota himalayana on Qinghai-Tibet plateau in China.

Pasteurella multocida is a zoonotic pathogen causing serious diseases in humans and animals. Here, we report P. multocida from wildlife on China's Qinghai-Tibet plateau with a novel capsular serotype, forming a single branch on the core-genome phylogenetic tree: four strains isolated from dead Himalayan marmot (Marmota himalayana) and one genome assembled from metagenomic sequencing of a dead Woolly hare (Lepus oiostolus). Four of the strains were identified as subspecies multocida and one was septica. The mouse model showed that the challenge strain killed mice within 24 h at an infectious dose of less than 300 bacteria. The short disease course is comparable to septicemic plague: the host has died before more severe pathological changes could take place. Though pathological changes were relatively mild, cytokine storm was obvious with a significant rise of IL-12p70, IL-6, TNF-αand IL-10 (P < 0.05). Our findings suggested P. multocida is a lethal pathogen for wildlife on Qinghai-Tibet plateau, in addition to Yersinia pestis. Individuals residing within the M. himalayana plague focus are at risk for P. multocida infection, and public health warnings are necessitated.

Combined genome and transcriptome provides insight into the genetic evolution of an edible halophyte Suaeda salsa adaptation to high salinity.

Suaeda salsa L. is a typical halophyte with high value as a vegetable. Here, we report a 447.98 Mb, chromosomal-level genome of S. salsa, assembled into nine pseudomolecules (contig N50 = 1.36 Mb) and annotated with 27,927 annotated protein-coding genes. Most of the assembled S. salsa genome, 58.03%, consists of transposable elements. Some gene families including HKT1, NHX, SOS and CASP related to salt resistance were significantly amplified. We also observed expansion of genes encoding protein that bind the trace elements Zn, Fe, Cu and Mn, and genes related to flavonoid and α-linolenic acid metabolism. Many expanded genes were significantly up-regulated under salinity, which might have contributed to the acquisition of salt tolerance in S. salsa. Transcriptomic data showed that high salinity markedly up-regulated salt-resistance related genes, compared to low salinity. Abundant metabolic pathways of secondary metabolites including flavonoid, unsaturated fatty acids and selenocompound were enriched, which indicates that the species is a nutrient-rich vegetable. Particularly worth mentioning is that there was no significant difference in the numbers of cis-elements in the promoters of salt-related and randomly selected genes in S. salsa when compared with Arabidopsis thaliana, which may affirm that plant salt tolerance is a quantitative rather than a qualitative trait in terms of promoter evolution. Our findings provide deep insight into the adaptation of halophytes to salinity from a genetic evolution perspective.

Elongatibacter sediminis gen. nov., sp. nov., isolated from intertidal sediment, and genomic comparison with all genera in the family Wenzhouxiangellaceae.

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).

Genome analysis of vB_SupP_AX, a novel N4-like phage infecting Sulfitobacter.

Sulfitobacter is a bacterium recognized for its production of AMP-independent sulfite oxidase, which is instrumental in the creation of sulfite biosensors. This capability underscores its ecological and economic relevance. In this study, we present a newly discovered phage, Sulfitobacter phage vB_SupP_AX, which was isolated from Maidao of Qingdao, China. The vB_SupP_AX genome is linear and double-stranded and measures 75,445 bp with a GC content of 49%. It encompasses four transfer RNA (tRNA) sequences and 79 open reading frames (ORFs), one of which is an auxiliary metabolic gene encoding thioredoxin. Consistent with other N4-like phages, vB_SupP_AX possesses three distinct RNA polymerases and is characterized by the presence of four tRNA molecules. Comparative genomic and phylogenetic analyses position vB_SupP_AX and three other viral genomes from the Integrated Microbial Genomes/Virus v4 database within the Rhodovirinae virus subfamily. The identification of vB_SupP_AX enhances our understanding of virus-host interactions within marine ecosystems.

Comparative genomic analysis and functional investigations for MCs catabolism mechanisms and evolutionary dynamics of MCs-degrading bacteria in ecology.

Microcystins (MCs) significantly threaten the ecosystem and public health. Biodegradation has emerged as a promising technology for removing MCs. Many MCs-degrading bacteria have been identified, including an indigenous bacterium Sphingopyxis sp. YF1 that could degrade MC-LR and Adda completely. Herein, we gained insight into the MCs biodegradation mechanisms and evolutionary dynamics of MCs-degrading bacteria, and revealed the toxic risks of the MCs degradation products. The biochemical characteristics and genetic repertoires of strain YF1 were explored. A comparative genomic analysis was performed on strain YF1 and six other MCs-degrading bacteria to investigate their functions. The degradation products were investigated, and the toxicity of the intermediates was analyzed through rigorous theoretical calculation. Strain YF1 might be a novel species that exhibited versatile substrate utilization capabilities. Many common genes and metabolic pathways were identified, shedding light on shared functions and catabolism in the MCs-degrading bacteria. The crucial genes involved in MCs catabolism mechanisms, including mlr and paa gene clusters, were identified successfully. These functional genes might experience horizontal gene transfer events, suggesting the evolutionary dynamics of these MCs-degrading bacteria in ecology. Moreover, the degradation products for MCs and Adda were summarized, and we found most of the intermediates exhibited lower toxicity to different organisms than the parent compound. These findings systematically revealed the MCs catabolism mechanisms and evolutionary dynamics of MCs-degrading bacteria. Consequently, this research contributed to the advancement of green biodegradation technology in aquatic ecology, which might protect human health from MCs.

Taxonomic characterization and comparative genomic analysis of a novel Devosia species revealed that phenolic acid-degrading traits are ubiquitous in the Devosia genus.

Phenolic acids (PAs) are widely distributed allelochemicals in various environments. To better understand the fate of PAs in environments, a halotolerant PAs-degrading bacterium (named strain RR2S18T) isolated from rhizosphere soil was identified as a novel species of Devosia, named Devosia rhizosphaerae sp. nov. The strain initially degraded PAs into central ring-fission intermediates (protocatechuic acid) using the CoA-dependent non-ß-oxidation pathway. The produced ring-fission intermediates were then consecutively degraded by an ortho-cleavage reaction and the ß-ketoadipic acid pathway. A comparative genomics analysis of 62 Devosia strains revealed that PAs-degrading genes were ubiquitous in their genomes, indicating that PAs degradation is universal among members of this genus. The analysis also suggested that the genes involved in CoA-dependent non-ß-oxidation are inherent to Devosia strains, while those involved in ring-fission and ß-ketoadipic acid pathways were obtained by horizontal gene transfer.

Assembly and Genome Annotation of Different Strains of Apple Fruit Moth Virus (Cydia pomonella granulovirus).

Cydia pomonella granulovirus is a natural pathogen for Cydia pomonella that is used as a biocontrol agent of insect populations. The study of granulovirus virulence is of particular interest since the development of resistance in natural populations of C. pomonella has been observed during the long-term use of the Mexican isolate CpGV. In our study, we present the genomes of 18 CpGV strains endemic to southern Russia and from Kazakhstan, as well as a strain included in the commercial preparation "Madex Twin", which were sequenced and analyzed. We performed comparative genomic analysis using several tools. From comparisons at the level of genes and protein products that are involved in the infection process of virosis, synonymous and missense substitution variants have been identified. The average nucleotide identity has demonstrated a high similarity with other granulovirus genomes of different geographic origins. Whole-genome alignment of the 18 genomes relative to the reference revealed regions of low similarity. Analysis of gene repertoire variation has shown that BZR GV 4, BZR GV 6, and BZR GV L-7 strains have been the closest in gene content to the commercial "Madex Twin" strain. We have confirmed two deletions using read depth coverage data in regions lacking genes shown by homology analysis for granuloviruses BZR GV L-4 and BZR GV L-6; however, they are not related to the known genes causing viral pathogenicity. Thus, we have isolated novel CpGV strains and analyzed their potential as strains producing highly effective bioinsecticides against C. pomonella.

Comparative genomic analysis of five coprinoid mushrooms species.

Although coprinoid mushrooms are widely known for the phenomenon of deliquescence and production of fungal laccases and extracellular peroxygenases, the genome structure and genetic diversity of coprinoid mushroom species have not been extensively studied. To reveal the genomic structure and diversity in coprinoid mushroom species, the genomes of five coprinoid mushroom species were compared and analyzed. A total of 24,303 orthologous gene families, including 89,462 genes, were identified in the five species. The numbers of core, softcore, dispensable, and private genes were 5617 (25.6%), 1628 (7.4%), 2083 (9.5%), and 12,574 (57.4%), respectively. Differentiation time analysis revealed that Coprinellus micaceus and Coprinellus angulatus differentiated approximately 181.0 million years ago. Coprinopsis cinerea and Coprinopsis marcescibilis differentiated approximately 131.0 million years ago, and they were differentiated from Candolleomyces aberdarensis approximately 176.0 million years ago. Gene family contraction and expansion analyses showed that 1465 genes and 532 gene families were expanded, and 95 genes and 134 gene families were contracted. Ninety-five laccase-coding genes were detected in the five species, and the distribution of the laccase-coding genes in the five species was not uniform. These data provide a reference for a deeper understanding of the genetic structure of the genomes of coprinoid mushroom species. Furthermore, this study provides a reference for follow-up studies on the genome structure of coprinoid mushroom species and the diversity of specific functional genes.

Genetic characterization of tetracycline-resistant Staphylococcus aureus with reduced vancomycin susceptibility using whole-genome sequencing.

This study aimed to analyze the genetic characteristics of Staphylococcus aureus with reduced vancomycin susceptibility (RVS-SA). Whole-genome sequencing was performed on 27 RVS-SA clinical isolates, and comparative genomic analysis was performed using S. aureus reference strains. Pan-genome orthologous groups (POGs) were identified that were present in RVS-SA but absent in the reference strains, but further analysis showed that the presence of these POGs was influenced by tetracycline resistance rather than vancomycin resistance. Therefore, we restricted our analysis to tetracycline-resistant (tetR) RVS-SA and tetR vancomycin-susceptible S. aureus (VSSA). Phylogenomic analysis showed them to be closely related, and further analysis revealed the presence of an uncharacterized protein SAB0394 and the absence of lytA in tetR RVS-SA, which are involved in cell wall thickening. In summary, using whole-genome sequencing we identified gain or loss of genes in tetR RVS-SA strains. These findings provide insights into the investigation of mechanisms associated with reduced vancomycin susceptibility and have the potential to contribute to the development of molecular biomarkers for the rapid and efficient detection of RVS-SA.

Insights from cyanobacterial genomic and transcriptomic analyses into adaptation strategies in terrestrial environments.

Phylogenomic analysis of Nostocsp. MG11, a terrestrial cyanobacterium, and some terrestrial and freshwater Nostoc strains showed that the terrestrial strains grouped together in a distinctive clade, which reveals the effect of habitat on shaping Nostoc genomes. Terrestrial strains showed larger genomes and had higher predicted CDS contents than freshwater strains. Comparative genomic analysis demonstrated that genome expansion in the terrestrial Nostoc is supported by an increase in copy number of the core genes and acquisition of shared genes. Transcriptomic profiling analysis under desiccation stress revealed that Nostoc sp. MG11 protected its cell by induction of catalase, proteases, sucrose synthase, trehalose biosynthesis and maltodextrin utilization genes and maintained its normal metabolism during this condition by up-regulation of genes related to phycobilisomes and light reactions of photosynthesis, CO2 fixation and protein metabolism. These results provide insights into the strategies related to survival and adaptation of Nostoc strains to terrestrial environments.

Comparative study on gene expression in psoriatic lesions versus chronic wound healing processes.

Psoriasis and chronic ulcers not only significantly impair quality of life but also pose a challenge in dermatological treatment. This study aimed to identify new therapeutic targets and biomarkers for psoriasis and chronic ulcers by comparing their gene expression profiles. The gene expression profiles of psoriatic, wound and chronic ulcer patients, as well as healthy controls, were determined via RNA extraction and next-generation sequencing of biopsies. In order to identify biomarkers, functional enrichment, differential expression analysis and machine learning algorithms were implemented. It is worth mentioning that the genes IL17A, TNF, KRT16, MMP9, and CD44 exhibited substantial correlations with the pathogenesis of the conditions being studied. As evidenced by their AUC-ROC values approaching 0.90, machine learning models accurately identified these biomarkers. The differential gene expression was consequently validated via qRT-PCR, which highlighted the increased expression of matrix remodelling enzymes and inflammatory cytokines. Additionally, genes essential for maintaining epidermis integrity and facilitating wound healing exhibited downregulation. These insights into the molecular mechanisms of psoriasis and chronic ulcers pave the way for the development of targeted therapies, offering hope for improved treatment strategies.

Comparative Genomic Analysis of Salmonella enterica Serovar Typhimurium Isolates from Passerines Reveals Two Lineages Circulating in Europe, New Zealand, and the United States.

Salmonella enterica serovar Typhimurium strains from passerines have caused wild bird deaths and human salmonellosis outbreaks in Europe, Oceania, and North America. Here, we performed comparative genomic analysis to explore the emergence, genetic relationship, and evolution of geographically dispersed passerine isolates. We found that passerine isolates from Europe and the United States clustered to form two lineages (EU and US passerine lineages), which were distinct from major S. Typhimurium lineages circulating in other diverse hosts (e.g., humans, cattle, pigs, chickens, and other avian hosts, such as pigeons and ducks). Further, passerine isolates from New Zealand clustered to form a sublineage (NZ passerine lineage) of the US passerine lineage. We inferred that the passerine isolates mutated at a rate of 3.2 × 10-7 substitutions/site/year, and the US, EU, and NZ passerine lineages emerged in approximately 1952, 1970, and 1996, respectively. Isolates from the three lineages presented genetic similarity, such as lack of antimicrobial resistance genes and accumulation of the same virulence pseudogenes. In addition, genetic diversity due to microevolution existed in the three passerine lineages. Specifically, pseudogenization in the type 1 fimbrial gene fimC (deletion of G at position 87) was detected only in the US and NZ passerine isolates, while single-base deletions in type 3 secretion system effector genes (i.e., gogB, sseJ, and sseK2) cooccurred solely in the EU passerine isolates. These findings provide insights into the evolution, host adaptation, and epidemiology of S. Typhimurium in passerines. IMPORTANCE Passerine-associated S. Typhimurium strains have been linked to human salmonellosis outbreaks in recent years. Here, we investigated the phylogenetic relationship of globally distributed passerine isolates and profiled their genomic similarity and diversity. Our study reveals two passerine-associated S. Typhimurium lineages circulating in Europe, Oceania, and North America. Isolates from the two lineages presented phylogenetic and genetic signatures that were distinct from those of isolates from other hosts. The findings shed light on the host adaptation of S. Typhimurium in passerines and are important for source attribution of S. Typhimurium strains to avian hosts. Further, we found that S. Typhimurium definitive phage type 160 (DT160) from passerines, which caused decades-long human salmonellosis outbreaks in New Zealand and Australia, formed a sublineage of the US passerine lineage, suggesting that DT160 might have originated from passerines outside Oceania. Our study demonstrates the importance of whole-genome sequencing and genomic analysis of historical microbial collections to modern epidemiologic surveillance.

Idiomarina rhizosphaerae sp. nov. isolated from rhizosphere soil of Kalidium cuspidatum, and reclassification of Idiomarina andamanensis as Pseudidiomarina andamanensis comb. nov., and Idiomarina mangrovi as Pseudidiomarina mangrovi comb. nov.

A Gram-stain-negative, strictly aerobic, gliding motile, non-spore forming, rod-shaped indole-3-acetic acid producing bacterial strain, designated M1R2S28T, was isolated from the rhizosphere soil of Kalidium cuspidatum, in Tumd Right Banner, Inner Mongolia, China. Strain M1R2S28T grew at pH 5.0-10.0 (optimum 8.0), 10-45 °C (optimum 37 °C), in the presence of 0-20% (w/v) NaCl (optimum 5%). The phylogenetic trees based on the 16S rRNA gene sequences and the core-genome both revealed that strain M1R2S28T clustered tightly with Idiomarina loihiensis L2-TRT, and shared 99.3, 99.2, 98.7, and < 98.7% of the 16S rRNA gene sequence similarities with I. loihiensis L2-TRT, I. abyssalis KMM 227 T, I. ramblicola R22T, and all the other current type strains. The strain contained ubiquinone-8 (Q-8) as the sole respiratory quinone. Its major polar lipids were phosphatidylethanolamine, phosphatidylglycerol, diphosphatidylglycerol, an unidentified aminolipid, an unidentified phospholipid, and three unidentified lipids. Its major fatty acids were iso-C15:0, iso-C17:0, and iso-C17:1 ω9c. The genomic DNA G + C content was 46.8%. The average nucleotide identity based on BLAST (ANIb) and the digital DNA-DNA hybridization (dDDH) values of strain M1R2S28T to I. loihiensis L2-TRT, I. ramblicola R22T, and I. abyssalis KMM 227 T were 93.0, 82.9, and 81.8%, and 51.2, 26.0, and 25.0%, respectively. The phylogenetic and physiological results allowed the discrimination of strain M1R2S28T from its phylogenetic relatives. Idiomarina rhizosphaerae sp. nov. is, therefore, proposed with strain M1R2S28T (= CGMCC 1.19026 T = KCTC 92133 T) as the type strain. Additionally, based on the phylogenomic and genomic analysis results, Idiomarina andamanensis and Idiomarina mangrovi were transferred into genus Pseudidiomarina and be named Pseudidiomarina andamanensis comb. nov. and Pseudidiomarina mangrovi comb. nov., respectively.

Comparative genomic analysis of the genus Marinomonas and taxonomic study of Marinomonas algarum sp. nov., isolated from red algae Gelidium amansii.

Members of the genus Marinomonas are known for their environmental adaptation and metabolically versatility, with abundant proteins associated with antifreeze, osmotic pressure resistance, carbohydrase and multiple secondary metabolites. Comparative genomic analysis focusing on secondary metabolites and orthologue proteins was conducted with 30 reference genome sequences in the genus Marinomonas. In this study, a Gram-stain-negative, rod-shaped, non-flagellated and strictly aerobic bacterium, designated as strain E8T, was isolated from the red algae (Gelidium amansii) in the coastal of Weihai, China. Optimal growth of the strain E8T was observed at temperatures 25-30 °C, pH 6.5-8.0 and 1-3% (w/v) NaCl. The DNA G + C content was 42.8 mol%. The predominant isoprenoid quinone was Q-8 and the major fatty acids were C16:0, summed feature 3 and summed feature 8. The major polar lipids were phosphatidylglycerol (PG) and phosphatidylethanolamine (PE). Based on data obtained from this polyphasic taxonomic study, strain E8T should be considered as a novel species of the genus Marinomonas, for which the name Marinomonas algarum is proposed. The type strain is E8T (= KCTC 92201T = MCCC 1K07070T).

Streptomyces liliifuscus sp. nov and an anti-ginger plague agent Streptomyces liliiviolaceus sp. nov, two novel species isolated from soil of Lilium lancifolium.

Two novel strains of actinobacteria, ZYC-3T and BH-SS-21T, were isolated from Hunan Province, PR China. The fermentation broth of BH-SS-21T inhibited the rapid spread of ginger blast, unlike that of ZYC-3T. The taxonomic characteristics of ZYC-3T and BH-SS-21T were defined using a polyphasic approach. The analysis of the full-length 16S rRNA gene sequence revealed that ZYC-3T and BH-SS-21T represented members of the genus Streptomyces. ZYC-3T had less than 98.7% sequence similarities to all species of the genus Streptomyces, while BH-SS-21T exhibited 99.97, 98.95, 98.83, 98.82, 98.75 and less than 98.7% sequence similarities to 'Streptomyces dioscori' A217, Streptomyces ederensis JCM 4958T, Streptomyces glomeroaurantiacus NBRC 15418T, Streptomyces aurantiacus NBRC 13017T, Streptomyces umbrinus JCM 4521T and other species with validly published names in the genus Streptomyces. However, the digital DNA-DNA relatedness and average nucleotide identity values between ZYC-3T, BH-SS-21T, and their closely related strains were significantly lower than the recommended threshold values. Also, phenotypic, chemotaxonomic and genetic features distinguished ZYC-3T and BH-SS-21T from their reference strains. On the basis of their genotypic and phenotypic characteristics, strains ZYC-3T and BH-SS-21T were classified as representing novel species of the genus Streptomyces under the names Streptomyces liliifuscus sp. nov. ZYC-3T (=CICC 25040T=JCM 34560T=MCCC 1K04978T) and Streptomyces liliiviolaceus sp. nov. BH-SS-21T (=MCCC 1K06236T=JCM 34767T), respectively.

Whole genomic comparative analysis of Streptococcus pneumoniae serotype 1 isolates causing invasive and non-invasive infections among children under 5 years in Casablanca, Morocco.

BACKGROUND: Streptococcus pneumoniae serotype 1 remains a leading cause of invasive pneumococcal diseases, even in countries with PCV-10/PCV-13 vaccine implementation. The main objective of this study, which is part of the Pneumococcal African Genome project (PAGe), was to determine the phylogenetic relationships of serotype 1 isolates recovered from children patients in Casablanca (Morocco), compared to these from other African countries; and to investigate the contribution of accessory genes and recombination events to the genetic diversity of this serotype. RESULTS: The genome average size of the six-pneumococcus serotype 1 from Casablanca was 2,227,119 bp, and the average content of coding sequences was 2113, ranging from 2041 to 2161. Pangenome analysis of the 80 genomes used in this study revealed 1685 core genes and 1805 accessory genes. The phylogenetic tree based on core genes and the hierarchical bayesian clustering analysis revealed five sublineages with a phylogeographic structure by country. The Moroccan strains cluster in two different lineages, the five invasive strains clusters altogether in a divergent clade distantly related to the non-invasive strain, that cluster with all the serotype 1 genomes from Africa. CONCLUSIONS: The whole genome sequencing provides increased resolution analysis of the highly virulent serotype 1 in Casablanca, Morocco. Our results are concordant with previous works, showing that the phylogeography of S. pneumoniae serotype 1 is structured by country, and despite the small size (six isolates) of the Moroccan sample, our analysis shows the genetic cohesion of the Moroccan invasive isolates.

Genome sequencing and comparative genomic analysis of highly and weakly aggressive strains of Sclerotium rolfsii, the causal agent of peanut stem rot.

BACKGROUND: Stem rot caused by Sclerotium rolfsii is a very important soil-borne disease of peanut. S. rolfsii is a necrotrophic plant pathogenic fungus with an extensive host range and worldwide distribution. It can infect peanut stems, roots, pegs and pods, leading to varied yield losses. S. rolfsii strains GP3 and ZY collected from peanut in different provinces of China exhibited a significant difference in aggressiveness on peanut plants by artificial inoculation test. In this study, de-novo genome sequencing of these two distinct strains was performed aiming to reveal the genomic basis of difference in aggressiveness. RESULTS: Scleotium rolfsii strains GP3 and ZY, with weak and high aggressiveness on peanut plants, exhibited similar growth rate and oxalic acid production in laboratory. The genomes of S. rolfsii strains GP3 and ZY were sequenced by Pacbio long read technology and exhibited 70.51 Mb and 70.61 Mb, with contigs of 27 and 23, and encoded 17,097 and 16,743 gene models, respectively. Comparative genomic analysis revealed that the pathogenicity-related gene repertoires, which might be associated with aggressiveness, differed between GP3 and ZY. There were 58 and 45 unique pathogen-host interaction (PHI) genes in GP3 and ZY, respectively. The ZY strain had more carbohydrate-active enzymes (CAZymes) in its secretome than GP3, especially in the glycoside hydrolase family (GH), the carbohydrate esterase family (CBM), and the polysaccharide lyase family (PL). GP3 and ZY also had different effector candidates and putative secondary metabolite synthetic gene clusters. These results indicated that differences in PHI, secreted CAZymes, effectors and secondary metabolites may play important roles in aggressive difference between these two strains. CONCLUSIONS: The data provided a further understanding of the S. rolfsii genome. Genomic comparison provided clues to the difference in aggressiveness of S. rolfsii strains.

Comparative Analysis of Genome of Ehrlichia sp. HF, a Model Bacterium to Study Fatal Human Ehrlichiosis.

BACKGROUND: The genus Ehrlichia consists of tick-borne obligatory intracellular bacteria that can cause deadly diseases of medical and agricultural importance. Ehrlichia sp. HF, isolated from Ixodes ovatus ticks in Japan [also referred to as I. ovatus Ehrlichia (IOE) agent], causes acute fatal infection in laboratory mice that resembles acute fatal human monocytic ehrlichiosis caused by Ehrlichia chaffeensis. As there is no small laboratory animal model to study fatal human ehrlichiosis, Ehrlichia sp. HF provides a needed disease model. However, the inability to culture Ehrlichia sp. HF and the lack of genomic information have been a barrier to advance this animal model. In addition, Ehrlichia sp. HF has several designations in the literature as it lacks a taxonomically recognized name. RESULTS: We stably cultured Ehrlichia sp. HF in canine histiocytic leukemia DH82 cells from the HF strain-infected mice, and determined its complete genome sequence. Ehrlichia sp. HF has a single double-stranded circular chromosome of 1,148,904 bp, which encodes 866 proteins with a similar metabolic potential as E. chaffeensis. Ehrlichia sp. HF encodes homologs of all virulence factors identified in E. chaffeensis, including 23 paralogs of P28/OMP-1 family outer membrane proteins, type IV secretion system apparatus and effector proteins, two-component systems, ankyrin-repeat proteins, and tandem repeat proteins. Ehrlichia sp. HF is a novel species in the genus Ehrlichia, as demonstrated through whole genome comparisons with six representative Ehrlichia species, subspecies, and strains, using average nucleotide identity, digital DNA-DNA hybridization, and core genome alignment sequence identity. CONCLUSIONS: The genome of Ehrlichia sp. HF encodes all known virulence factors found in E. chaffeensis, substantiating it as a model Ehrlichia species to study fatal human ehrlichiosis. Comparisons between Ehrlichia sp. HF and E. chaffeensis will enable identification of in vivo virulence factors that are related to host specificity, disease severity, and host inflammatory responses. We propose to name Ehrlichia sp. HF as Ehrlichia japonica sp. nov. (type strain HF), to denote the geographic region where this bacterium was initially isolated.

Whole genome de novo sequencing and comparative genomic analyses suggests that Chlamydia psittaci strain 84/2334 should be reclassified as Chlamydia abortus species.

BACKGROUND: Chlamydia abortus and Chlamydia psittaci are important pathogens of livestock and avian species, respectively. While C. abortus is recognized as descended from C. psittaci species, there is emerging evidence of strains that are intermediary between the two species, suggesting they are recent evolutionary ancestors of C. abortus. Such strains include C. psittaci strain 84/2334 that was isolated from a parrot. Our aim was to classify this strain by sequencing its genome and explore its evolutionary relationship to both C. abortus and C. psittaci. RESULTS: In this study, methods based on multi-locus sequence typing (MLST) of seven housekeeping genes and on typing of five species discriminant proteins showed that strain 84/2334 clustered with C. abortus species. Furthermore, whole genome de novo sequencing of the strain revealed greater similarity to C. abortus in terms of GC content, while 16S rRNA and whole genome phylogenetic analysis, as well as network and recombination analysis showed that the strain clusters more closely with C. abortus strains. The analysis also suggested a closer evolutionary relationship between this strain and the major C. abortus clade, than to two other intermediary avian C. abortus strains or C. psittaci strains. Molecular analyses of genes (polymorphic membrane protein and transmembrane head protein genes) and loci (plasticity zone), found in key virulence-associated regions that exhibit greatest diversity within and between chlamydial species, reveal greater diversity than present in sequenced C. abortus genomes as well as similar features to both C. abortus and C. psittaci species. The strain also possesses an extrachromosomal plasmid, as found in most C. psittaci species but absent from all sequenced classical C. abortus strains. CONCLUSION: Overall, the results show that C. psittaci strain 84/2334 clusters very closely with C. abortus strains, and are consistent with the strain being a recent C. abortus ancestral species. This suggests that the strain should be reclassified as C. abortus. Furthermore, the identification of a C. abortus strain bearing an extra-chromosomal plasmid has implications for plasmid-based transformation studies to investigate gene function as well as providing a potential route for the development of a next generation vaccine to protect livestock from C. abortus infection.

De novo genome assembly of a foxtail millet cultivar Huagu11 uncovered the genetic difference to the cultivar Yugu1, and the genetic mechanism of imazethapyr tolerance.

BACKGROUND: Setaria italica is the second-most widely planted species of millets in the world and an important model grain crop for the research of C4 photosynthesis and abiotic stress tolerance. Through three genomes assembly and annotation efforts, all genomes were based on next generation sequencing technology, which limited the genome continuity. RESULTS: Here we report a high-quality whole-genome of new cultivar Huagu11, using single-molecule real-time sequencing and High-throughput chromosome conformation capture (Hi-C) mapping technologies. The total assembly size of the Huagu11 genome was 408.37 Mb with a scaffold N50 size of 45.89 Mb. Compared with the other three reported millet genomes based on the next generation sequencing technology, the Huagu11 genome had the highest genomic continuity. Intraspecies comparison showed about 94.97 and 94.66% of the Yugu1 and Huagu11 genomes, respectively, were able to be aligned as one-to-one blocks with four chromosome inversion. The Huagu11 genome contained approximately 19.43 Mb Presence/absence Variation (PAV) with 627 protein-coding transcripts, while Yugu1 genomes had 20.53 Mb PAV sequences encoding 737 proteins. Overall, 969,596 Single-nucleotide polymorphism (SNPs) and 156,282 insertion-deletion (InDels) were identified between these two genomes. The genome comparison between Huagu11 and Yugu1 should reflect the genetic identity and variation between the cultivars of foxtail millet to a certain extent. The Ser-626-Aln substitution in acetohydroxy acid synthase (AHAS) was found to be relative to the imazethapyr tolerance in Huagu11. CONCLUSIONS: A new improved high-quality reference genome sequence of Setaria italica was assembled, and intraspecies genome comparison determined the genetic identity and variation between the cultivars of foxtail millet. Based on the genome sequence, it was inferred that the Ser-626-Aln substitution in AHAS was responsible for the imazethapyr tolerance in Huagu11. The new improved reference genome of Setaria italica will promote the genic and genomic studies of this species and be beneficial for cultivar improvement.