Project description:We report the application of transcriptome sequencing technology for high-throughput profiling of Serratia marcescens for producing prodigiosin. By obtaining over 163 million bases of sequence from Serratia marcescens genome DNA, we generated transcriptome -state maps of Serratia marcescens 12h cells, 24h cells, and 36h cells at 30C and 37C,respectively. We explored the mechanism of S. marcescens response temperature regulation at the transcription level through transcriptome sequencing technology. We found that the pig gene cluster at low temperature would favor at the transcriptional level, however, higher temperature resulting in instability and loss of enzyme activity. Numerous amino acid metabolic pathways involved in prodigiosin biosynthesis in S. marcescens responded to temperature changes, and metabolic fluxes were directed towards prodigiosin biosynthesis. At the same time, quorum sensing, two-component regulatory system and sRNA were stimulated by temperature to regulate PG biosynthesis and involve strain virulence and exclusive genes. Moreover, inhibition factors was the one reason for S. marcescens incapable synthesis of prodigiosin at 37C. This study laid a good foundation for understanding the biological functions of prodigiosin, improving the temperature tolerance of industrial strains, and excavating temperature-sensitive regulatory elements.
Project description:Serratia marcescens is a bacterium frequently found in the environment, but over the last several decades it has evolved into a concerning clinical pathogen, causing fatal bacteremia. To establish such infections, pathogens require specific nutrients; one very limited but essential nutrient is iron. We sought to characterize the iron acquisition systems in S. marcescens isolate UMH9, which was recovered from a clinical bloodstream infection. Using RNA sequencing (RNA-seq), we identified two predicted siderophore gene clusters (cbs and sch) that were regulated by iron. Mutants were constructed to delete each iron acquisition locus individually and in conjunction, generating both single and double mutants for the putative siderophore systems. Mutants lacking the sch gene cluster lost their iron-chelating ability as quantified by the chrome azurol S (CAS) assay, whereas the cbs mutant retained wild-type activity. Mass spectrometry-based analysis identified the chelating siderophore to be serratiochelin, a siderophore previously identified in Serratia plymuthica. Serratiochelin-producing mutants also displayed a decreased growth rate under iron-limited conditions created by dipyridyl added to LB medium. Additionally, mutants lacking serratiochelin were significantly outcompeted during cochallenge with wild-type UMH9 in the kidneys and spleen after inoculation via the tail vein in a bacteremia mouse model. This result was further confirmed by an independent challenge, suggesting that serratiochelin is required for full S. marcescens pathogenesis in the bloodstream. Nine other clinical isolates have at least 90% protein identity to the UMH9 serratiochelin system; therefore, our results are broadly applicable to emerging clinical isolates of S. marcescens causing bacteremia.
Project description:The spread of carbapenemase-producing Enterobacterales (CPE) is emerging as a significant clinical concern in tertiary hospitals and in particular, long-term care facilities with deficiencies in infection control. This study aims to evaluate an advanced matrix-assisted laser desorption/ionization mass spectrometry (A-MALDI) method for the identification of carbapenemases and further discrimination of their subtypes in clinical isolates. The A-MALDI method was employed to detect CPE target proteins. Enhancements were made to improve detectability and mass accuracy through the optimization of MALDI-TOF settings and internal mass calibration. A total of 581 clinical isolates were analyzed, including 469 CPE isolates (388 KPC, 51 NDM, 40 OXA, and 2 GES) and 112 carbapenemase-negative isolates. Clinical evaluation of the A-MALDI demonstrated 100% accuracy and precision in identifying all the collected CPE isolates. Additionally, A-MALDI successfully discriminated individual carbapenemase subtypes (KPC-2 or KPC-3/4; OXA-48 or OXA-181 or OXA-232; GES-5 or GES-24) and also differentiated co-producing carbapenemase strains (KPC & NDM; KPC & OXA; KPC & GES; NDM & OXA), attributed to its high mass accuracy and simultaneous detection capability. A-MALDI is considered a valuable diagnostic tool for accurately identifying CPE and carbapenemase’s subtypes in clinical isolates. It may also aid in selecting appropriate antibiotics for each carbapenemase subtype. Ultimately, we expect that the A-MALDI method will contribute to preventing the spread of antibiotic resistance and improving human public health.
Project description:The spread of carbapenemase-producing Enterobacterales (CPE) is emerging as a significant clinical concern in tertiary hospitals and in particular, long-term care facilities with deficiencies in infection control. This study aims to evaluate an advanced matrix-assisted laser desorption/ionization mass spectrometry (A-MALDI) method for the identification of carbapenemases and further discrimination of their subtypes in clinical isolates. The A-MALDI method was employed to detect CPE target proteins. Enhancements were made to improve detectability and mass accuracy through the optimization of MALDI-TOF settings and internal mass calibration. A total of 581 clinical isolates were analyzed, including 469 CPE isolates (388 KPC, 51 NDM, 40 OXA, and 2 GES) and 112 carbapenemase-negative isolates. Clinical evaluation of the A-MALDI demonstrated 100% accuracy and precision in identifying all the collected CPE isolates. Additionally, A-MALDI successfully discriminated individual carbapenemase subtypes (KPC-2 or KPC-3/4; OXA-48 or OXA-181 or OXA-232; GES-5 or GES-24) and also differentiated co-producing carbapenemase strains (KPC & NDM; KPC & OXA; KPC & GES; NDM & OXA), attributed to its high mass accuracy and simultaneous detection capability. A-MALDI is considered a valuable diagnostic tool for accurately identifying CPE and carbapenemase’s subtypes in clinical isolates. It may also aid in selecting appropriate antibiotics for each carbapenemase subtype. Ultimately, we expect that the A-MALDI method will contribute to preventing the spread of antibiotic resistance and improving human public health.
Project description:In order to identify changes in the global mRNA transcriptome caused by deletion of the RNA-binding protein Hfq in Serratia marcescens, total mRNA was isolated from wild type Serratia marcescens Db10 and an otherwise isogenic strain carrying an in-frame deletion of the hfq gene (SMDB11_4482) and analysed by RNAseq. Four independent biological replicates were sequenced for each strain using the Illumina HiSeq platform. The data was used to identify the nature and extent of changes in transcript level between the two strains and to inform on the role of Hfq in virulence of Serratia marcescens, an opportunist bacterial pathogen.
Project description:In order to identify mRNA and sRNAs associated with the RNA-binding protein Hfq in Serratia marcescens strain Db10, Hfq-bound RNA was immunoprecipitated from a strain encoding an Hfq-3FLAG fusion protein at the normal location and sequenced, in parallel with the wild type strain (no fusion) as negative control. Additionally global transcriptional start site mapping was performed on total RNA, with or without TEX treatment, isolated from wild type Serratia marcescens. The data was used to identify regions of mRNA and sRNAs associated with Hfq in this organism. Associated work in Serratia marcescens Db10, an opportunistic bacterial pathogen, has shown that Hfq is essential for virulence in several models and exerts a wide-ranging impact on the transcriptome and, particularly, genes encoding virulence factors.
Project description:Transcriptional profiling of P. pacificus young adult worms exposed to pathogen Serratia marcescens for 4 hours versus age-matched worms exposed to control lab food E. coli OP50. The goal was to identify genes regulated in response to pathogen. The broader goal of study was to study evolution of pathogen response by comparing this expression profile to that obtained by exposing the nematode C. elegans to the same pathogen. Other experiments which are a part of this study include expression profiling of C. elegans and P. pacificus on other pathogens including , Bacillus thuringiensis DB27, Serratia marcescens and Xenorhabdus nematophila. One-condition experiments. P. pacificus young adults: Exposed to Serratia marcescens versus exposed to E. coli OP50 : 4 hours. 4 biological replicates for each condition, including 2 dye-swaps.