Microbial Pathogenesis

The cryptococcal Amt family of ammonium transporters have been identified from our previous studies as one of the most highly upregulated proteins during transmigration in an in vitro blood-brain barrier (BBB) model, however, the role of this gene family has never been reported. Therefore, this study aimed to investigate the role of the Amt2 gene in the transmigration of C. neoformans across the BBB, examine its association with other common virulence factors, and assess its relevance to morphological changes in C. neoformans. The results showed that the C. neoformans mutant strain lacking the Amt2 gene (amt2{Delta}) exhibited a significantly reduced ability to transmigrate across the BBB in an in vitro model. Our findings suggest that C. neoformans primarily utilizes a transcellular mechanism for invasion, as indicated by the FITC-dextran permeability assays. Additionally, the size of polysaccharide capsule was significantly smaller in the mutant strain compared to the wild-type. In conclusion, our study proposed that the Amt2 gene plays a crucial role in both the transmigration process and capsule production in C. neoformans, without affecting morphological changes. Our study provides a foundation for future research into the underlying mechanisms of the Amt2 gene in C. neoformans pathogenesis. Author summaryCryptococcus neoformans transmigrates the blood-brain barrier through various mechanisms, with transcellular migration being the major route leading to cryptococcal meningitis. In this study, we identified the Amt2 gene, a member of the Amt family of ammonium transporters, as playing a crucial role in the funguss transmigration process. Our findings indicate that the Amt2 gene promotes capsule production and facilitates the transmigration of C. neoformans, all while not causing damage to human endothelial cells.

Dengue infections are considered an increasing threat to mankind due to their rapid global spread rate. The development of a widely accepted drug/vaccine is hindered due to an incomplete understanding of the virus lifecycle. Present data suggest that a cytoskeleton protein, called MYH9 binds to the 3UTR, at A4 region, a highly conserved part of the UTR across the serotypes. The levels of this protein were found to be elevated in the cells infected with the virus and the above increase is commensurate with the virus load. This protein is found to accumulate at the endoplasmic reticulum (site of virus replication) and interacts with dsRNA (a replicative intermediate), suggesting its involvement in replication. Inhibition of this proteins expression by its siRNA reduced viral load, supporting its role in viral replication. Immunofluorescence studies indicate that this protein accumulates at the cell periphery and pulldown studies suggest that this protein interacts with the viral envelope protein, suggesting a role in the dengue viruss cellular entry, possibly by acting as a receptor. Use of an anti-MYH9 drug, ML-7 indicated the reduction of the virus load, prevented the accumulation at the periphery and aided in regaining the cell morphology of virus infected cells, confirming its role in replication and entry. Collectively, these studies demonstrate a dual function of MHY9 in the virus life cycle, which may serve as a general paradigm for the other viruses and hence to develop specific drugs.

In the present study, we assessed the pathogenicity of H5N8 avian influenza viruses belongs to the clade 2.3.4.4b in chicken. Birds of three different dose groups, 102, 104, and 106 EID50 were used in the study. No mortality was observed in 102 EID0 group. Percent cumulative mortality of 104 and 106 EID50 group was 66.67 and 100 %, respectively. Varying duration of MDT of 3.2 and 2 days was observed in 104 and 106 EID50 group, respectively. The CID50 of virus was found to be 104.5 EID50. High no. of viral RNA copies were found both in oropharyngeal and cloacal swabs and in various organs of birds infected in 104 and 106 EID50 group. Significant gross and histological changes and presence of viral antigen in various organs were observed in 104 and 106 EID50 group. So, the study concludes that Indian HPAI, H5N8 isolates are highly pathogenic in nature to chicken by affecting most organs systemically. CID50 of this H5N8 virus indicates poor adaption in chicken and it implies poor transmission possibility of this virus for host species in field condition. Though this virus is highly pathogenic in nature as that of HPAI, H5N1 viruses, absence of endothelial staining in most organ attributes variation in replication process and pathogenesis from HPAI, H5N1 viruses. Hence, further studies need to be done to elucidate the pathobiology of this virus in various bird species. HighlightsO_LIH5N8 virus belong to the clade 2.3.4.4b, Indian isolate is highly pathogenic in nature as that of HPAIV, H5N1. C_LIO_LIThe dose inocula, 102 EID50 is noninfectious to chicken. C_LIO_LIThe dose inocula, 104 and 106 EID50 had caused significant mortality in the inoculated chicken with MDT of 2 and 3.2 days, respectively. C_LIO_LIH5N8 virus was detected with high viral titres in clocal and oral shedding and in multiple organ with the dose inocula, 104 and 106 EID50. C_LIO_LI104 and 106 EID50 of H5N8 inocula virus caused significant gross and histological changes in multiple organs and viral antigens were detected in respective organs. C_LI

This work explores the relationship between glucose uptake by human endothelial cells and infection by Human Herpesvirus 8 (HHV8). The results indicate that HHV8-infected endothelial cells uptake significantly more glucose than uninfected cells. In addition, when the endothelial cells are treated with diabetes type 2 serums (DM2), the uptake of glucose is even greater in HHV8 infected cells, but it is significantly depressed in not-infected cells. The authors conclude that HHV8 infection could play a role in metabolic modifications which characterize DM2 patients.

Cell-mediated immune responses are crucial for protecting the host against Toxoplasma gondii infection. However, impaired immunity, such as T-cell exhaustion, is a common phenomenon during chronic infection. This may represent a strategy employed by T. gondii to evade host defenses. T-cell immunoglobulin and mucin-domain containing 3 (Tim-3) is an important regulatory molecule involved in cell-mediated immunity. This study examined the expression of Tim-3 and the effects of its blockade in a mouse model of toxoplasmosis. In mice with chronic T. gondii infection, we found that Tim-3 is highly expressed in both cyst-bearing and non-cyst-bearing tissues, and its expression correlates with the parasite burden. Blocking the Tim-3 pathway with an anti-Tim-3 antibody enhances the immune response, resulting in elevated levels of cytokines (IFN-{gamma}, IL-12p70, IL-2, IL-9) and the chemokine CXCL1 in the serum, increased leukocyte infiltration (CD3+, CD14+ cells) in the brain, and downregulation of Tim-3 expression in microglial cells. As a result, the anti-Tim-3 treatment resulted in a 62% reduction in the number of tissue cysts and a trend towards an increase in the homeostatic signature, P2RY12, in microglia. Our study provides proof of concept for an anti-Tim-3 approach in treating chronic T. gondii infection and potentially other brain-residing pathogens.

RATIONALEThe host-protective role of alpha-1-antitrypsin (AAT) against mycobacteria may be partly attributed to its binding to the cytoplasmic glucocorticoid receptor (GR) that results in gene regulation in macrophages that favors killing of ingested mycobacteria. The AAT-GR complex was found to be significantly responsible for limiting Mycobacterium avium complex (MAC) burden in macrophages; this host-protective function of AAT-GR is due, in part, to induction of COLONY STIMULATING FACTOR-2 (CSF-2) gene which encodes for granulocyte-monocyte colony stimulating factor (GM-CSF). METHODSTo better understand the role of AAT-GR binding during mycobacterial infection, we performed bulk RNA sequencing (RNA-seq) on four different groups of cells: (i) control THP-1 cells (THP-1control); (ii) THP-1control cells infected with Mycobacterium intracellulare (MAC); (iii) THP-1control cells incubated with MAC + AAT; and (iv) THP-1 cells knocked down for GR (THP-1GR-KD) incubated with MAC + AAT. RESULTSOur analyses revealed that MAC infection significantly upregulated 1,977 genes and significantly downregulated 2,303 genes in THP-1control cells. Additionally, AAT significantly upregulated 1,200 genes and downregulated 890 genes in MAC-infected THP-1control cells. Furthermore, the regulation of 1,624 genes that are regulated by AAT+GR in THP-1control cells was augmented in THP-1GR-KD cells, indicating that the regulation of these genes by AAT+MAC is inhibited by GR. Conversely, the regulation of 1,683 genes by AAT+MAC in THP-1control cells was attenuated in THP-1GR-KD cells, indicating that the regulation of these genes by AAT+MAC is enhanced by GR. MAC also induced both CSF2 (GM-CSF) and CSF1 (encodes for monocyte colony stimulating factor, M-CSF) expression. Whereas AAT inhibited MAC-induced M-CSF mRNA was dependent on GR, this inhibition of M-CSF protein was not dependent on GR. In contrast, AAT did not inhibit MAC-induced CSF2 (GM-CSF) expression. Since either MAC or AAT induced GM-CSF expression in macrophages, further investigation revealed that AAT-inhibition of cell-associated MAC burden was abrogated upon neutralization of endogenous GM-CSF. CONCLUSIONSThe ability of AAT to induce GM-CSF and to inhibit MAC-induced M-CSF may skew macrophages to a phenotype that is better endowed to control mycobacterial infection.

The R2TP is a multimeric protein complex consists of RUVBL1, RUVBL2, PIH1D1, and RPAP3, and it is known to functions as a specialized co-chaperone. We hypothesize that PIH1D1 recognizes p53 and stabilizes it via R2TP complex. Upon successful completion of this study, innovative mechanism has been found for the interaction and stabilization of p53 and hence govern the cell cycle. Upon interaction between p53 and PIH1D1 protein, p53 is stabilized by PIH1D1 protein, without affecting its C-terminal domain. We have also observed that p53 protein levels were affected after the alteration in expression levels of PIH1D1. Based on the finding, we suggest that the R2TP complex stabilizes and regulates P53. Therefore, this novel method will work as a flashpoint to restore the function of p53 in cancer cells, controlling cancer and cell cycle progression.

Mycoplasma synoviae is an avian pathogen that causes respiratory disease and synovitis, and its hemagglutinin plays a critical role in host cell adhesion. However, the key residues and structural mechanisms underlying hemagglutination remain unclear. In this study, domain analysis of the hemagglutinin family of Mycoplasma synoviae revealed that it contains long-chain and short-chain types, among which LAM HA (VY93_RS01465) was selected as the bait protein due to its complete C-terminal conserved domain. Through yeast two-hybrid screening, 18 host proteins interacting with LAM HA were identified. Furthermore, five key amino acid residues S83, R85, Y88, N124, and K192 were found to mediate hemagglutination activity. Deletion of these residues reduced the hemagglutination titer of LAM HA under acidic conditions. Secondary structure analysis showed that the deletion mutation decreased the -helix content while increasing the proportions of {beta}-sheet and random coil. Molecular dynamics simulations revealed that the mutant exhibited generally higher root mean square deviation and root mean square fluctuation values than the wild-type under different pH conditions, with a marked decrease in structural stability particularly at pH 5.0 and 6.0. These findings indicate that LAM HA, as a critical adhesin, exerts its hemagglutination function dependent on specific key residues and pH-sensitive conformational stability. IMPORTANCEMycoplasma synoviae (M. synoviae) causes significant economic losses to the poultry industry worldwide. Lipid-related membrane protein hemagglutinin (LAM HA) is a surface adhesin essential for host cell attachment, but its precise amino acid residues and structural features have not been defined. In this study, five key residues (S83, R85, Y88, N124, and K192) were identified as critical for LAM HA-mediated hemagglutination activity. Deletion of these residues altered the secondary structure composition, reduced conformational stability under acidic pH conditions, and decreased hemagglutination activity. These findings reveal a previously unknown structure-function relationship of M. synoviae LAM HA, demonstrating that its hemagglutination activity depends on specific residues and pH-sensitive structural integrity. This provides new insights into the molecular mechanisms of M. synoviae adhesion and offers potential targets for the development of novel intervention strategies against avian mycoplasmosis.

It has been known for decades that bacteriophages encode tRNA genes, but their function and the factors contributing to their acquisition and retention are unclear. Although tRNAs are found in a variety of phages infecting a variety of bacteria, many large-scale computational studies investigating tRNA acquisition and retention in phages are specific to Mycobacterium phages; however, these findings may not be representative of other phages or bacteria. This work uses a broader sampling of phages and hosts to investigate the relationships between codon usage bias, infection cycle, and tRNA gene numbers in phage genomes. We analyzed 154 phages infecting 7 host genera, including Gram-negative (Escherichia, Shigella, Salmonella) and Gram-positive (Bacillus, Lactobacillus, Staphylococcus, Mycobacterium) bacteria. Phages included temperate and virulent representatives, plus a range of tRNA numbers and morphologies. All phages and hosts were analyzed using four metrics: GC content, Effective Number of Codons, Relative Synonymous Codon Usage, and tRNA Adaptation Index. On a global scale, virulent phages with many tRNA genes show greater differences in codon usage and codon adaptation compared to their respective hosts. Gram-negative bacteria and their phages generally exhibit greater differences in codon usage compared to Gram-positive bacteria and their phages. Phages infecting Gram-negative hosts also tend to encode more tRNA genes. In nearly all genus-level comparisons, Mycobacterium phages were different from any other host and from global patterns. This suggests previous computational studies performed in Mycobacterium phages are likely not applicable on a global scale or to phages infecting other host genera. AUTHOR SUMMARYBacteriophages, or phages, are viruses infecting bacteria. They are abundant in all environments, yet how they interact with their bacterial hosts is still not well-understood. Like other viruses, phages must rely on the host translational components to replicate and form new phage particles; and similarly to other parasites, phages have genomes that differ significantly from their hosts in terms of composition. In this work, we explore the relationship between phage lifestyle, number of tRNA genes encoded, and genome differences from the host using a variety of phages and their associated hosts. Phages can be either virulent (do not integrate into the host genome) or temperate (capable of integrating into the host genome), with differences from the host genome more pronounced in virulent phages. There are many phages that also carry tRNA genes, and having higher numbers of tRNAs is associated with larger differences from the host genome. The findings here indicate that virulent phages carrying large numbers of tRNAs diverge the most from host genome composition.

Successful transmission of malaria depends on the complex interactions between the Anopheles mosquito vector and the Plasmodium parasites. Plasmodium ovale, a neglected malaria parasite, successfully develops from ookinete to sporozoite within the Anopheles vector. To elucidate the molecular mechanisms underlying this interaction, we compared RNA-seq-based gene expression profiles of Anopheles gambiae infected with P. ovale and uninfected mosquitoes at 24 hours, 9 days, and 17 days post-infection. The results showed that 2,885 P. ovale transcripts were present only 24 hours after infection. During ookinete invasion (24 h post-infection), differential gene expression analyses revealed the up-regulation of genes related to metabolic processes and the down-regulation of genes associated with cytoskeletal activity in the mosquito. Notably, the non-immune genes with unspecific function AGAP003776, (Fold Change, FC 132.0), AGAP003777, (FC 88.3), and AGAP003778, (FC 104.1), Troponin C (Fold Change, FC 85) and Myofilin (FC 33.3) exhibited the most significant overexpression. Among the immune genes that were upregulated CTL3 (FC 55.9), CLIPB12 (FC 49.4), CTLMA5 (FC 14.5), TRYP7 (FC 24.4), CLIP C9 (FC 12.1) TRYP5 (FC 12.2), LRIM10 (FC 11.2), PPO6 (FC 7.7). This initial analysis of the interaction between P. ovale and An. gambiae identified several well-known candidates for transmission-blocking strategies, including LRIM1, APN1, and D7 family proteins. In addition, new potential candidates, including AGAP003776, AGAP003777, and AGAP003778 cluster, CLIPB12, LRIM10, the APN cluster, AGAP004860, ABCC9, CYP9K1 and GSTD3 were identified. These potential new candidate genes could play a significant role in the development of transmission-blocking strategies for An. gambiae infected with Plasmodium, particularly P. ovale. The urgent functional validation of these genes is required.

The present study evaluated the immunogenicity and protective efficacy of the chitosan (CS)-modified poly-lactide-co-glycolic acid (PLGA) nanoparticles (NPs) delivering Brucella abortus L7/L12 DNA in a mouse model. The NPs were prepared by solvent displacement method and characterized for size, charge, morphology, cellular uptake and cytotoxicity. The cationic CS-PLGA NPs were spherical with a mean size of [~]165 nm with a positive zeta potential (+20 mV). DNA loading efficiency of 1.2% and DNA adsorption shifted zeta potential to -45 mV. In vitro studies in RAW 264.7 cell line demonstrated efficient uptake of the DNA loaded cationic NPs and expression of L7/L12 protein. Intramuscular immunization of the L7/L12 DNA vaccine loaded CS-PLGA NPs elicited both humoral and cell-mediated immunity with upregulation of Th1 and Th2 cytokines along with induction of IgG antibodies in mice. IFN-{gamma}, IL-2, and IL-4 levels were significantly (P < 0.001) higher than control group. The protective efficacy of the DNA loaded NPs against virulent B. abortus 544 infection (105 CFU) was significantly higher than that of the naked DNA (P<0.001). These findings suggest that the CS-PLGA NPs were efficiently delivered L7/L12 DNA and exhibited adjuvant potential, conferring protection against experimental murine brucellosis.

BackgroundAcinetobacter baumannii is a common bacterial pathogen in nosocomial infections. It has become one of the greatest threats to human health for its growing resistance to last resort antibiotics, which has led to a revival of phage therapy as a potential treatment. However, conventional methods for isolating A. baumannii-infecting phages are labor-intensive and often unsuccessful. MethodsOur approach involves a computational pipeline to identify temperate phages (prophages) integrated into A. baumannii genomes, followed by mitomycin C (MMC) induction of those strains to screen for active prophages. ResultsHere we show a prophage analysis for nearly 900 A. baumannii genomes. We observed MMC-triggered excision of nine prophages from eight A. baumannii strains by PCR and sequencing. Further we show four prophage form virions detectable by transmission electron microscopy, and two which can plaque on other A. baumannii isolates. ConclusionThis work demonstrates the utility and diversity of prophages for further development as therapeutics for antibiotic resistant A. baumannii.

Campylobacter jejuni is a leading global cause of acute foodborne gastroenteritis however, C. jejuni lacks some of the classic virulence determinants associated with other common enteric bacterial pathogens. In recent years an increasing number of C. jejuni isolates have been identified to encode Type Six Secretion System (T6SS), an apparatus utilised by Gram-negative bacteria to secrete toxic bacterial effectors into neighbouring cells. Despite the prevalence of the T6SS and previous investigations, the roles of the C. jejuni T6SS are still not well characterised especially when compared to our knowledge of other clinically relevant T6SS-positive bacterial species. Additionally, as of yet, no C. jejuni T6SS cargo effectors have been characterised. In this study, we show the C. jejuni 488 strain T6SS displays contact-dependent antagonistic behaviour towards T6SS-negative C. jejuni, Campylobacter coli, Escherichia coli and Enterococcus faecium strains suggesting the presence of the T6SS contributes to the competitive capacity of this C. jejuni T6SS-positive strain. Moreover, this antagonistic activity is linked to the functionality of CJ488_0980 and CJ488_0982, two novel putative Tox-REase-7 domain-containing effectors, which were identified through bioinformatical analysis of the C. jejuni 488 strain genome. Additionally, our investigations propose the C. jejuni 488 T6SS contributes to interaction, invasion and intracellular survival in human intestinal epithelial cells (IEC). Collectively, these initial findings are the first examples of in vitro investigation of putative cargo effectors in Campylobacter spp. and provide valuable insights into the roles of C. jejuni T6SS effectors in bacterial competition and pathogenesis. This study highlights the importance of T6SS as an emerging virulence determinant in Campylobacter spp. warranting further investigation.

The study presented here shows Biofilm quantification in microtiter plates in strains of Candida auris and Candida albicans evaluated by means of Crystal violet, MTT, ATP-Luminescence and NBTZ/BCIP assays. The results showed significant differences in biofilm formation between Candida auris and Candida albicans but also within Candida auris outbreak strains in contrast to Candida auris DSM 21092 reference strain.

Varicella Zoster Virus (VZV) is a dsDNA virus that infects dermal cells and causes characteristic cutaneous lesions. The virus undergoes neurotropism and later causes secondary cycles of infection. In the host nucleus, Promyelocytic Leukaemia Nuclear Bodies (PML-NBs) spontaneously form around the VZV genome to repress viral gene expression. VZV encodes for a ubiquitin E3 ligase ORF61 to disperse PML-NBs and alleviate repression. ORF61 functions as a ubiquitin E3 ligase with a conserved RING domain at the N-terminal end. It carries three SUMO-interacting motifs (SIMs) that mediate interactions with SUMOylated proteins within PML bodies. The mechanism by which ORF61 disperses PML-NBs is poorly understood. To understand how ORF61 interacts with SUMOylated proteins, we investigated its interaction with SUMO and studied its SUMO-Targeted Ubiquitin Ligase (STUbL) activity. Our studies reveal that ORF61 co-opts the E2D family for ubiquitination activity. A specific network of interactions between the E2 enzyme, ORF61, and Ub facilitates polyubiquitination. ORF61 can synthesize branched polyubiquitin chains of K11, K48, and K63 linkages. The C-terminal SIM in ORF61 is a high-affinity binder of SUMO chains. Utilizing the SIM, ORF61 targets specific lysines on SUMO chains for ubiquitination. These studies provide crucial insights into the functional mechanism of viral STUbL ORF61.

The MAT_HMGbox domain in the MAT1-1-1 protein and the HMG-box_ROX1-like domain in the MAT1-2-1 protein play essential roles in DNA binding and regulating the transcription of genes that control sexual reproduction in Ophiocordyceps sinensis. Previous studies have documented differential occurrences, differential transcription, and alternative splicing of the MAT1-1-1 and MAT1-2-1 and pheromone receptor genes in Hirsutella sinensis (Genotype #1 among 17 genome-independent O. sinensis genotypic fungi). This study further revealed that the DNA-binding domains of the paired MAT1-1-1 and MAT1-2-1 proteins derived from each of the 20 O. sinensis strains exhibit heteromorphic tertiary structures, as predicted by AlphaFold 3D structural modeling. The differentially paired mating proteins, characterized by different truncations, 1-4 amino acid substitutions at distinct sites, altered hydrophobicity and secondary structures, and heteromorphic tertiary structures, indicate divergency in the fungal origins of the mating proteins within the mycologically and genetically impure O. sinensis strains. These findings support the hypothesis of O. sinensis self-sterility and are likely ensure the fidelity and genetic diversity of heterothallic or hybrid reproduction throughout the lifecycle of the Cordyceps sinensis insect-fungal complex.

Mycobacterium tuberculosis (Mtb) primarily infects human lung macrophages, which serve as its major replication niche. Mtb can manipulate host macrophage cell death pathways to its advantage by inhibiting apoptosis and inducing necrotic cell death. However, the specific necrotic cell death pathway activated in human macrophages after Mtb infection remains unclear. Here, we used the THP-1 cell line and primary human monocyte-derived macrophage (hMDM) to analyze multiple programmed cell death pathways during days 1-3 after Mtb infection. Confocal microscopic analysis demonstrates that Mtb-infected THP-1 cells or hMDMs rarely exhibited apoptosis. Immunoblotting shows that Mtb induces significant CASP3 and GSDME activation in THP-1 cells, but not in hMDMs. We show that Mtb, in THP-1 cells but not hMDM, induces a significant increase in GSDMD cleavage, a hallmark of pyroptosis. MLKL phosphorylation was not observed in THP-1 cells or hMDMs during Mtb infections, indicating an absence of necroptosis. No changes in ferroptosis markers such as GPX4 expression or lipid peroxidation levels were detected. Time-lapse live-cell imaging revealed no lysosomal membrane permeabilization prior to plasma membrane rupture (PMR). However, we observed DNA release from Mtb-infected THP-1 cells and hMDMs after PMR. The DNA released from THP-1 cells exhibits low levels of myeloperoxidase and histone H3 citrullination. High-resolution confocal imaging shows that Mtb is associated with the released DNA. We demonstrate that pyroptosis induction in THP-1 cells is dispensable for the DNA release and cell death induction. In conclusion, our results reveal that Mtb-triggered cell death in hMDMs bypasses canonical cell death pathways like apoptosis, pyroptosis, necroptosis, and ferroptosis. Instead, cell death in both THP-1 cells and hMDMs correlates with DNA release, potentially through a pathway similar to NETosis in neutrophils.

Regulator of G-protein signaling 10 (RGS10) has been shown to regulate multiple inflammatory pathways relevant to disease pathogenesis. Of particular importance is the ability of RGS10 to negatively regulate the NFkB pathway, a prominent pro-inflammatory pathway implicated in multiple inflammatory disease phenotypes. However, the exact mechanism by which RGS10 regulates NFkB is unknown. Considering that RGS10 translocates into the nucleus upon stimulation, we hypothesize that RGS10 may regulate NFKB through transcription. To determine whether RGS10 mediates NFkB transcription, we stimulated RGS10 KO and B6 peritoneal macrophages and collected cell lysate over 24 hours to assess transcript levels of NFkB and related proinflammatory cytokines. Here we found that RGS10 differentially regulates the transcription of N{kappa}KB subunits and NF{kappa}B-dependent cytokines. Further studies are warranted to understand the potential role of RGS10 in transcriptional regulation of inflammatory states.

Non-pathogenic Xanthomonas (NPX) from a diverse plant hosts are being reported on an increasing basis. There are also reports of multiple species forming communities on a single host plant, such as rice, and, given their role as core endophytes in protecting plants from pathogens, it is essential to isolate and characterization of more NPX species from diverse host plants. Using phylogenomic analysis of publicly available Xanthomonas genome sequences, we identified a novel clade comprising NPX strains from diverse hosts. One of the strains previously reported from our lab is from healthy rice seeds and was reported to be non-pathogenic, with bio-protection function against the bacterial leaf blight pathogen. Genomic investigation confirmed the lack of type III secretion system and its effectors, consistent with their non-pathogenic nature. These strains also harbour core and unique biosynthetic loci identified in other non-pathogenic Xanthomonas (NPX) strains. Further investigation using multiple genomic-based taxonomic indices indicates that these strains represent a potential new species. Hence, we propose Xanthomonas imtechensis sp. nov. as a new species of the genus Xanthomonas, with the type strain being PPL568 = MTCC 13186 = CFBP 9040 = ICMP 24395.

It is well established that Staphylococcus aureus can incorporate straight-chain unsaturated fatty acids (SCUFAs) into its lipids in addition to the normally biosynthesized branched-chain and straight-chain saturated fatty acids. Incorporation of oleic acid into S. aureus lipids has recently been shown to significantly enhance S. aureus growth at low temperatures due to the greater fluidity imparted to the membrane. Here, we show that low-temperature growth of S. aureus is not limited to oleic acid but enhanced also by various antimicrobial SCUFAs when present at low concentrations. A fakA-deficient strain did not show SCUFA-induced growth stimulation, which indicates that the fatty acid kinase is necessary for SCUFA incorporation into membrane lipids to promote low-temperature growth. Determination of total lipid fatty acid composition showed that incorporated SCUFAs make up [~]12% or less of the total fatty acids. Lipidomic investigations revealed elevated synthesis of diglucosyldiglyceride in the absence or presence of SCUFAs. SCUFAs were incorporated into diglucosyldiglyceride to a greater extent than phosphatidyglycerol at both 12 {degrees}C and 37 {degrees}C. The presence of SCUFAs at low temperatures also enhanced production of the carotenoid staphyloxanthin. The results suggest that multiple strategies are at play in the membrane adaptation of S. aureus to low temperatures. Inclusion of oleic acid in media decreased the minimum growth temperature of S. aureus, suggesting that the presence of SCUFAs in food may facilitate the growth of S. aureus at low temperature. Also, incorporation of SCUFAs into lipids may promote the disruption of the membrane by SCUFAs.