Evolutionary trends of carbapenem-resistant and susceptible Acinetobacter baumannii isolates in a major tertiary care setting from North India.

Emergence of carbapenem-resistant A. baumannii (CRAB) is a global, ongoing healthcare concern. CRAB is among the topmost priority pathogens, with various studies focusing on its global population structure and resistant allelic profiles. However, carbapenem-susceptible A. baumannii (CSAB) isolates are often overlooked due to their sensitivity to beta-lactams, which can provide important insights into origin of CRAB lineages and isolates. In the present study, we report genomic investigation of CRAB and CSAB coexisting in Indian hospital setting. MLST based population structure and phylogenomics suggest they mainly follow distinct evolutionary routes forming two phylogroups. PG-I exclusively for a successful clone (ST2) of CRAB and PG-II comprises diversified CSAB isolates except PG3373, which is CRAB. Additionally, there are few CRAB isolates not belonging to PG-I and sharing clonal relationship with CSAB isolates indicating role of genome plasticity towards extensive drug resistance in the nosocomial environment. Further, genealogical analysis depicts prominent role of recombination in emergence and evolution of a major CRAB lineage. Further, CRAB isolates are enriched in resistomes as compared to CSAB isolates, which were encoded on the genomic island. Such comparative genomic insights will aid in our understanding and localized management of rapidly evolving pandrug resistant nosocomial pathogens.

Evaluation of Human Dental Plaque Lactic Acid Bacilli for Probiotic Potential and Functional Analysis in Relevance to Oral Health.

Members of the lactic acid bacillus group are well-known probiotics and primarily isolated from fermented food, dairy products, intestinal and gut environment of human. Since probiotics from the human source are preferred, there exists a huge repertoire of lactobacilli in the human oral cavity which could prove a much better niche to be exploited for these beneficial microorganisms. Therefore, in this study, four lactobacilli strains, including strain DISK7, reported earlier, isolated from dental plaque samples of a healthy humans were evaluated for their probiotic potential. Strains displayed 99.9% of 16S rRNA gene sequence identity with species of the genera Lactobacillus and Limosilactobacillus. All strains showed lactic acid production, tolerance to low pH and antibiotic sensitivity. Variations were observed among strains in their aggregation ability, biofilm formation, bile salt resistance and cholesterol degradation. Further, we analyzed the interaction of strains with other oral commensals and opportunistic pathogens in co-culture experiments. Isolates DISK7 and DISK26 exhibited high co-aggregation (> 70%) with secondary colonizers, Streptococcus pyogenes and Veillonella parvula, respectively, but their aggregation ability was decreased with opportunistic pathogens. Furthermore, strains showed a substantial increase in biofilm in co-culture with other Lactobacillus isolates, indicating their ability to proliferate commensal bacteria in the oral environment. These microbes continually evolve in terms of niche adaptation as evidenced in genome analysis. The highlight of the investigation is the isolation and evaluation of the probiotic lactobacilli from the human oral cavity, which could prove a much better niche to be exploited for the effective commercialization of these beneficial microbes. Taken together, probiotic properties and interaction with commensal bacteria, these isolates exhibit the huge potential to be developed as alternative bioresource agents for maintenance of oral health. Supplementary Information: The online version contains supplementary material available at 10.1007/s12088-023-01108-2.

Lysobacter arvi sp. nov. Isolated from Farmland Soil.

A bacterial strain designated as UC was isolated from farmland soil. Strain UCT formed a pale yellow colony on nutrient agar. Cell morphology revealed it as the rod-shaped bacterium that stained Gram-negative. The 16S rRNA gene sequence analysis identified strain UCT as a member of the genus Lysobacter that showed high identity with L. soli DCY21T (99.5%), L. panacisoli CJ29T (98.7%), and L. tabacisoli C8-1T (97.9%). It formed a distinct cluster with these strains in the neighbor-joining phylogenetic tree. A similar tree topology was observed in TYGS-based phylogenomic analysis. However, genome sequence analyses of strain UCT showed 87.7% average nucleotide identity and 34.7% digital DNA-DNA hybridization similarity with the phylogenetically closest species, L. soli DCY21T. The similarity was much less with other closely related strains of the genus Lysobacter. The G + C content of strain UCT was 68.1%. Major cellular fatty acids observed were C14:0 iso (13.4%), C15:0 iso (13.6%), and C15:0 anteiso (14.8%). Quinone Q-8 was the major respiratory ubiquinone. Predominant polar lipids were phosphatidylethanolamine, diphosphatidylglycerol, and phosphatidylglycerol. Production of xanthomonadin pigment was observed. Based on phenotypic differences and phylogenomic analysis, strain UCT represents a novel species of the genus Lysobacter, for which the name Lysobacter arvi is proposed. The type strain of the novel species is UCT (= KCTC 92613T = JCM 23757T = MTCC 12824T).

Genomic features, antimicrobial susceptibility, and epidemiological insights into Burkholderia cenocepacia clonal complex 31 isolates from bloodstream infections in India.

Introduction: Burkholderia cepacia complex (Bcc) clonal complex (CC) 31, the predominant lineage causing devastating outbreaks globally, has been a growing concern of infections in non-cystic fibrosis (NCF) patients in India. B. cenocepacia is very challenging to treat owing to its virulence determinants and antibiotic resistance. Improving the management of these infections requires a better knowledge of their resistance patterns and mechanisms. Methods: Whole-genome sequences of 35 CC31 isolates obtained from patient samples, were analyzed against available 210 CC31 genomes in the NCBI database to glean details of resistance, virulence, mobile elements, and phylogenetic markers to study genomic diversity and evolution of CC31 lineage in India. Results: Genomic analysis revealed that 35 isolates belonging to CC31 were categorized into 11 sequence types (ST), of which five STs were reported exclusively from India. Phylogenetic analysis classified 245 CC31 isolates into eight distinct clades (I-VIII) and unveiled that NCF isolates are evolving independently from the global cystic fibrosis (CF) isolates forming a distinct clade. The detection rate of seven classes of antibiotic-related genes in 35 isolates was 35 (100%) for tetracyclines, aminoglycosides, and fluoroquinolones; 26 (74.2%) for sulphonamides and phenicols; 7 (20%) for beta-lactamases; and 1 (2.8%) for trimethoprim resistance genes. Additionally, 3 (8.5%) NCF isolates were resistant to disinfecting agents and antiseptics. Antimicrobial susceptibility testing revealed that majority of NCF isolates were resistant to chloramphenicol (77%) and levofloxacin (34%). NCF isolates have a comparable number of virulence genes to CF isolates. A well-studied pathogenicity island of B. cenocepacia, GI11 is present in ST628 and ST709 isolates from the Indian Bcc population. In contrast, genomic island GI15 (highly similar to the island found in B. pseudomallei strain EY1) is exclusively reported in ST839 and ST824 isolates from two different locations in India. Horizontal acquisition of lytic phage ST79 of pathogenic B. pseudomallei is demonstrated in ST628 isolates Bcc1463, Bcc29163, and BccR4654 amongst CC31 lineage. Discussion: The study reveals a high diversity of CC31 lineages among B. cenocepacia isolates from India. The extensive information from this study will facilitate the development of rapid diagnostic and novel therapeutic approaches to manage B. cenocepacia infections.

Comparative genomics reveals the emergence of copper resistance in a non-pigmented Xanthomonas pathogen of grapevine.

Xanthomonas citri pv. viticola (Xcv) is the causal agent of bacterial canker in grapevine. The pathogen is restricted to India, where it was first reported in the 1970s, and Brazil. In the present study, we report the first complete genome sequence of Xcv LMG965, which is a reference pathotype strain. We also report genome sequences of additional isolates from India and comparative genome-based studies of isolates from Brazil. Apart from revealing the monophyletic origin of the pathovar, we could also confirm a common frameshift mutation in a gene that is part of the Xanthomonadin pigment biosynthetic gene cluster in all the isolates. The comparative study also revealed multiple intrinsic copper resistance-related genes in Brazilian isolates, suggesting intense selection, possibly because of heavy and indiscriminate usage of copper as an antimicrobial agent in the orchards. There is also the association of a Tn3-like transposase in the vicinity of the copper resistance genes, indicating a potential for rapid diversification through horizontal gene transfer events. The findings, along with genomic resources, will allow for systematic genetic and functional studies of Xcv.

Taxonomic and Phylogenomic Assessment Identifies Phytopathogenicity Potential of Stenotrophomonas maltophilia Complex.

Stenotrophomonas maltophilia is a versatile bacterium found in plants, water, air, and even hospital settings. Deep taxono phylogenomics studies have revealed that S. maltophilia is a complex of several hidden species that are not differentiated using conventional approaches. In the last two decades, there have been increasing reports of S. maltophilia as a pathogen of diverse plants. Hence, proper taxonogenomic assessment of plant-pathogenic strains and species within the S. maltophilia complex (Smc) is required. In the present study, we formally propose a taxonomic amendment of Pseudomonas hibiscicola and P. beteli, reported as pathogens of Hibiscus rosa-sinensis and Betelvine (Piper betle) plants, respectively, as a misclassified member species of the Smc. Recently, a novel species of the genus, S. cyclobalanopsidis, was reported as a leaf spot pathogen of the oak tree genus Cyclobalanopsis. Interestingly, our investigation also revealed S. cyclobalanopsidis as another plant-pathogenic member species of the Smc lineage. In addition, we provide deep phylo-taxonogenomic evidence that S. maltophilia strain JZL8, reported as a plant pathogen, is a misclassified strain of S. geniculata, making it the fourth member species of the Smc harboring plant-pathogenic strains. Therefore, a proper taxonomic assessment of plant-pathogenic strains and species from the Smc is required for further systematic studies and management.

UVC-Based Air Disinfection Systems for Rapid Inactivation of SARS-CoV-2 Present in the Air.

The World Health Organization (WHO) declared in May 2021 that SARS-CoV-2 is transmitted not only by close contact with infectious respiratory fluids from infected people or contaminated materials but also indirectly through air. Airborne transmission has serious implications for the control measures we can deploy, given the emergence of more transmissible variants. This emphasizes the need to deploy a mechanism to reduce the viral load in the air, especially in closed and crowded places such as hospitals, public transport buses, etc. In this study, we explored ultraviolet C (UVC) radiation for its ability to inactivate the SARS-CoV-2 particles present in aerosols and designed an air disinfection system to eliminate infectious viruses. We studied the virus inactivation kinetics to identify the UVC dosage required to achieve maximum virus inactivation. Based on the experimental data, UVC-based devices were designed for the sanitization of air through HVAC systems in closed spaces. Further, a risk assessment model to estimate the risk reduction was applied which showed that the use of UVC radiation could result in the reduction of the risk of infection in occupied spaces by up to 90%.

Limosilactobacillus walteri sp. nov., a novel probiotic antimicrobial lipopeptide-producing bacterium.

A Gram-positive facultative anaerobe, nonspore forming, and nonmotile bacterial strain M31 was isolated from faecal contaminated soil. The strain is previously reported to produce a novel antimicrobial lipopeptide and displayed probiotic properties. The strain M31 is catalase negative and fermented d-galactose, d-glucose, esculin, d-maltose, d-lactose, d-melibiose, d-raffinose, d-saccharose (weak reaction), d-xylose (weak reaction), d-ribose (weak reaction), and l-arabinose (weak reaction). The majority of fatty acids were C16:0 (53.9%), C18:0 (26.9%), and C19:0 cyclo ω8c (19.1%). The genome is 2 234 040 bp long with 38.81% guanine-cytosine (GC) content. The pairwise ortho average nucleotide identity and digital DNA-DNA hybridization values of strain M31 with its closest relative species from Limosilactobacillus reuteri clade and Lm. rudii is below the recommended cut-off of 95% and 70%, respectively. Herein, we propose Lm. walteri sp. nov. as a novel species of the genus Limosilactobacillus with M31 = MTCC 12838 = JCM 32759 = KCTC 25569.

Insights into the Diversity of Transcription Activator-Like Effectors in Indian Pathotype Strains of Xanthomonas oryzae pv. oryzae.

Xanthomonas oryzae pv. oryzae (Xoo) is a major rice pathogen, and its genome harbors extensive inter-strain and inter-lineage variations. The emergence of highly virulent pathotypes of Xoo that can overcome major resistance (R) genes deployed in rice breeding programs is a grave threat to rice cultivation. The present study reports on a long-read Oxford nanopore-based complete genomic investigation of Xoo isolates from 11 pathotypes that are reported based on their reaction toward 10 R genes. The investigation revealed remarkable variation in the genome structure in the strains belonging to different pathotypes. Furthermore, transcription activator-like effector (TALE) proteins secreted by the type III secretion system display marked variation in content, genomic location, classes, and DNA-binding domain. We also found the association of tal genes in the vicinity of regions with genome structural variations. Furthermore, in silico analysis of the genome-wide rice targets of TALEs allowed us to understand the emergence of pathotypes compatible with major R genes. Long-read, cost-effective sequencing technologies such as nanopore can be a game changer in the surveillance of major and emerging pathotypes. The resource and findings will be invaluable in the management of Xoo and in appropriate deployment of R genes in rice breeding programs.

Lacrimispora defluvii PI-S10-B5AT sp. nov., an Obligate Anaerobe, Isolated from an Industrial Waste and Reclassification of Hungatella xylanolytica as Lacrimispora xylanolytica and Clostridium indicum as Lacrimispora indica Comb. nov.

A bacterial strain was isolated from the waste slurry of an industrial effluent treatment plant near Patancheru, Hyderabad, India, and designated as PI-S10-B5AT. It was an obligately anaerobic, spore-forming, rod-shaped, motile bacterium that stained Gram-positive. The strain revealed high 16S rRNA gene sequence identity with Hungatella xylanolytica DSM 3808T (99.4%) followed by members of the genus Lacrimispora (98.8-93.3%). However, the average nucleotide identity (ANI) and digital DNA-DNA hybridization of genome sequence exhibited similarity in the range of 94.3-68.7% and 57.4-18.8%, respectively, with all closely related strains. A multi-gene phylogenetic analysis of strain PI-S10-B5AT was performed to investigate the taxonomic affiliation, which revealed formation of a coherent cluster with the members of the genus Lacrimispora. The DNA G + C content was 41.8 mol%. Major polar lipids were glyco- and phospholipids. The fatty acids analysis showed C16:0 to be the major fatty acid. The predominant respiratory quinone was menaquinone-7 (MK-7). Based on phenotypic, chemotaxonomic, and whole-genome phylogenetic analysis, strain PI-S10-B5AT is assigned as a novel species of the genus Lacrimispora, for which the name Lacrimispora defluvii is proposed. The type strain of the novel species is PI-S10-B5AT (= MTCC 12280T; = DSM 24980T) isolated from waste slurry of effluent treatment plant. The genomic analysis of type strains of C. indicum PI-S10-A1BT and H. xylanolytica DSM 3808T showed ANI and AAI values consistent with members of the genus Lacrimispora. Therefore, these strains are ascertained to the genus Lacrimispora and reclassified as Lacrimispora indica and Lacrimispora xylanolytica comb. nov.

Genome dynamics mediated by repetitive and mobile elements in Xanthomonas citri pv. durantae.

Xanthomonas is a highly evolved group of phytopathogenic bacteria infecting nearly 400 host plants having vast genomic resources available with heterogenicity in representation from different species and pathovars. Unfortunately, the wealth of data is extremely biased and restricted to a few Xanthomonas pathogens that infect economically important plants, while those reported to infect the most diverse plants remain neglected. In the present study, we report the first complete genome sequence of Xanthomonas citri pv. durantae that was reported to infect Duranta repens L. or golden dewdrop, a hedge plant of ornamental importance native to the American region. Phylogenomic analysis with its closest relatives placed it amongst X. citri pv. citri A* pathotype strains and further comparative studies revealed various large unique genomic regions of chromosomal origin. The association of integrative and conjugative elements and prophages with unique genomic regions suggests the role of mobilome in genome dynamics. A large number of IS elements and transcription activator-like effectors encoding genes on each of the four plasmids indicate the further scope of diversification in Xanthomonas .

Xanthomonas indica sp. nov., a Novel Member of Non-Pathogenic Xanthomonas Community from Healthy Rice Seeds.

Xanthomonas is a major group of pathogenic bacteria infecting staple food crops like rice. Increasingly it is being recognized that non-pathogenic Xanthomonas (NPX) are also important members of a healthy plant microbiome. However, the vast majority of the species described in this genus are of pathogenic nature, and only a few NPX species have been reported till now. Genomic and taxonogenomic analysis of NPX is needed for the management of this important group of bacteria. In this study, two yellow-pigmented bacterial isolates were obtained from healthy rice seeds in Punjab, India. The isolates designated PPL560T and PPL568 were identified as members of the genus Xanthomonas based on biochemical tests and 16S rRNA gene sequence analysis retrieved from the whole-genome sequences. Isolates formed a distinct monophyletic lineage with Xanthomonas sontii and Xanthomonas sacchari as the closest relatives in the phylogenetic tree based on core gene content shared by the representative species of the genus Xanthomonas. Pairwise ortho Average Nucleotide Identity and digital DNA-DNA hybridization values calculated against other species of Xanthomonas were below their respective cut-offs. In planta studies revealed that PPL560T and PPL568 are non-pathogenic to rice plants upon leaf clip inoculation. The absence of type III secretion system-related genes and effectors further supported their non-pathogenic status. Herein, we propose Xanthomonas indica sp. nov. as novel species of the genus Xanthomonas with PPL560T = MTCC 13185 = CFBP 9039 = ICMP 24394 as its type strain and PPL568 as another constituent member.

Deep Population Genomics Reveals Systematic and Parallel Evolution at a Lipopolysaccharide Biosynthetic Locus in Xanthomonas Pathogens That Infect Rice and Sugarcane.

The advent of high-throughput sequencing and population genomics has enabled researchers to investigate selection pressure at hypervariable genomic loci encoding pathogen-associated molecular pattern (PAMP) molecules like lipopolysaccharide (LPS). Xanthomonas is a model and a major group of phytopathogenic bacteria that infect hosts in tissue-specific manner. Our in-depth population-based genomic investigation revealed the emergence of major lineages in two Xanthomonas pathogens that infect xylem of rice and sugarcane is associated with the acquisition and later large-scale replacement by distinct type of LPS cassettes. In the population of the rice xylem pathogen, Xanthomonas oryzae pv. oryzae (Xoo) and sugarcane pathogens Xanthomonas sacchari (Xsac) and Xanthomonas vasicola (Xvv), the BXO8 type of LPS cassette is replaced by a BXO1 type of cassette in Xoo and by Xvv type LPS cassette in Xsac and Xvv. These findings suggest a wave of parallel evolution at an LPS locus mediated by horizontal gene transfer (HGT) events during its adaptation and emergence. Aside from xylem pathogens, two closely related lineages of Xoo that infect parenchyma of rice and Leersia hexandra grass have acquired an LPS cassette from Xanthomonas pathogens that infect parenchyma of citrus, walnut, and strawberries, indicating yet another instance of parallel evolution mediated by HGT at an LPS locus. Our targeted and megapopulation-based genome dynamic studies revealed the acquisition and dominance of specific types of LPS cassettes in adaptation and success of a major group of phytopathogenic bacteria. IMPORTANCE Lipopolysaccharide (LPS) is a major microbe associated molecular pattern and hence a major immunomodulator. As a major and outer member component, it is expected that LPS is a frontline defense mechanism to deal with different host responses. Limited studies have indicated that LPS loci are also highly variable at strain and species level in plant-pathogenic bacteria, suggesting strong selection pressure from plants and associated niches. The advent of high-throughput genomics has led to the availability of a large set of genomic resources at taxonomic and population levels. This provides an exciting and important opportunity to carryout megascale targeted and population-based comparative genomic/association studies at important loci like those encoding LPS biosynthesis to understand their role in the evolution of the host, tissue specificity, and also predominant lineages. Such studies will also fill major gap in understanding host and tissue specificity in pathogenic bacteria. Our pioneering study uses the Xanthomonas group of phytopathogens that are known for their characteristic host and tissue specificity. The present deep phylogenomics of diverse Xanthomonas species and its members revealed lineage association and dominance of distinct types of LPS in accordance with their origin, host, tissue specificity, and evolutionary success.

Genomic data resource of type strains of genus Pseudoxanthomonas.

Genus Pseudoxanthomonas represents a relatively newly characterized group of gamma-proteobacterium of environmental origin. Species of the genus have very similar morphology to strains belonging to Xanthomonas, Xylella and Stenotrophomonas. However, the genome resource of this genus was largely unexplored. The species belonging to the genus are from a wide range of environmental sites including hydrocarbon polluted fields. Here, we have provided the whole genome sequence of all available type strains of the genus of Pseudoxanthomonas. In order to deduce the differences with closely related genera, we have employed the whole genome-based investigation of the type species of genus Pseudoxanthomonas.

Novel insights into the role of the mobilome in ecological diversification and success of Staphylococcus haemolyticus as an opportunistic pathogen.

Staphylococcus haemolyticus is a species of coagulase-negative staphylococci that has primarily been studied as a human skin microbiome member and an emerging nosocomial pathogen. Here, we present the first complete genome of S. haemolyticus strains SE3.9, SE3.8 and SE2.14 reported as an endophyte of rice seed. Detailed investigation of the genome dynamics of strains from diverse origins revealed an expanded genome size in clinical isolates, and a role of many insertion sequence (IS) elements in strain diversification. Interestingly, several of the IS elements are also unique or enriched in a particular habitat. Comparative studies also revealed the potential movement of mobile elements from rice endophytic S. haemolyticus to strains from other pathogenic species such as Staphylococcus aureus. The study highlights the importance of ecological studies in the systematic understanding of genome plasticity and management of medically important Staphylococcus species.

Phylo-Taxonogenomics Supports Revision of Taxonomic Status of 20 Xanthomonas Pathovars to Xanthomonas citri.

Based on phylo-taxonogenomics criteria, we present amended descriptions for 20 pathovars to Xanthomonas citri. Incidentally, 18 were first reported from India. Seven out of twenty are classified as X. axonopodis, 12 out of 20 as X. campestris, and one as X. cissicola. In this study, we have generated genome sequence data of four pathovars, and the genomes of the remaining 16 were used from the published data. Comprehensive genome-based phylogenomic and taxonogenomic analyses reveal that all these pathovars belong to X. citri and need to reconcile their taxonomic status. This proposal will aid in systematic studies of a major species and its constitutent members that infect economically important plants.

Deep phylo-taxono genomics reveals Xylella as a variant lineage of plant associated Xanthomonas and supports their taxonomic reunification along with Stenotrophomonas and Pseudoxanthomonas.

Genus Xanthomonas is a group of phytopathogens that is phylogenetically related to Xylella, Stenotrophomonas, and Pseudoxanthomonas, having diverse lifestyles. Xylella is a lethal plant pathogen with a highly reduced genome, atypical GC content and is taxonomically related to these three genera. Deep phylo-taxono genomics reveals that Xylella is a variant Xanthomonas lineage that is sandwiched between Xanthomonas clades. Comparative studies suggest the role of unique pigment and exopolysaccharide gene clusters in the emergence of Xanthomonas and Xylella clades. Pan-genome analysis identified a set of unique genes associated with sub-lineages representing plant-associated Xanthomonas clade and nosocomial origin Stenotrophomonas clade. Overall, our study reveals the importance of reconciling classical phenotypic data and genomic findings in reconstituting the taxonomic status of these four genera. SIGNIFICANCE STATEMENT: Xylella fastidiosa is a devastating pathogen of perennial dicots such as grapes, citrus, coffee, and olives. An insect vector transmits the pathogen to its specific host wherein the infection leads to complete wilting of the plants. The genome of X. fastidiosa is significantly reduced both in terms of size (2 Mb) and GC content (50%) when compared with its relatives such as Xanthomonas, Stenotrophomonas, and Pseudoxanthomonas that have higher GC content (65%) and larger genomes (5 Mb). In this study, using systematic and in-depth genome-based taxonomic and phylogenetic criteria and comparative studies, we assert the need to unify Xanthomonas with its relatives (Xylella, Stenotrophomonas and Pseudoxanthomonas). Interestingly, Xylella revealed itself as a minor variant lineage embedded within two major Xanthomonas lineages comprising member species of different hosts.

Xanthomonas sontii sp. nov., a non-pathogenic bacterium isolated from healthy basmati rice (Oryza sativa) seeds from India.

We report three yellow-pigmented, Gram-negative, aerobic, rod-shaped, motile bacterial isolates designated as PPL1T, PPL2, and PPL3 from healthy basmati rice seeds. Phenotypic and 16S rRNA gene sequence analysis assigned these isolates to the genus Xanthomonas. The 16S rRNA showed a 99.59% similarity with X. sacchari CFBP 4641T, a sugarcane pathogen. Further, biochemical and fatty acid analysis revealed it to be closer to X. sacchari. Still, it differed from other species in general and known rice associated species such as X. oryzae (pathogenic) and X. maliensis (non-pathogenic) in particular. Interestingly, the isolatess in this study were isolated from healthy rice plants but are closely related to species that is pathogenic and isolated from diseased sugarcane. Accordingly, in planta studies revealed that PPL1T, PPL2, and PPL3 are non-pathogenic to rice plants upon leaf inoculation. Taxonogenomic studies based on orthologous average nucleotide identity (OrthoANI) and digital DNA-DNA hybridization (dDDH) values with type strains of Xanthomonas species were below the recommended threshold values for species delineation. Whole genome-based phylogenomic analysis revealed that these isolates formed a distinct monophyletic clade with X. sacchari CFBP 4641T as their closest neighbour. Further, pangenome analysis revealed PPL1T, PPL2, and PPL3 isolates to comprise NRPS cluster along with a large number of unique genes associated with the novel species. Based on polyphasic and genomic approaches, a novel lineage and species associated with healthy rice seeds for which the name Xanthomonas sontii sp. nov. is proposed. The type strain for the X. sontii sp. nov. is PPL1T (JCM 33631T = CFBP 8688T = ICMP 23426T = MTCC 12491T) and PPL2 (JCM 33632 = CFBP 8689 = ICMP 23427 = MTCC 12492) and PPL3 (JCM 33633 = CFBP 8690 = ICMP 23428 = MTCC 12493) as other strains of the species.