Project description:This study aimed to compare differentially expressed transcripts in Salmonella recovered from the inoculated onion bulbs using transcriptome profiling (RNA-seq). The Salmonella strains of Salmonella enterica subsp. enterica ser. Newport, isolated from clinical cases affected by the onion-linked outbreak in 2020 (CDC, 2020), was used for the onion bulb inoculation. Transcriptomic analysis of Salmonella was performed 1 day (24 hours) and 7 days post-inoculation to identify Differentially Expressed Genes (DEGs) . 925 and 736 genes were upregulated within 24 hours and seven days after inoculation, while the number of downregulated genes in the same timeframe was 690 and 826, respectively (FDR<0.05 and Abs (log 2(Y/X) >0).
Project description:The obligate intracellular bacterium, Ehrlichia ruminantium (ER) is the causal agent of Heartwater, a fatal disease in ruminants. It is transmitted by ticks of the genus Amblyomma. Here, we report the genomic comparative and the global transcriptional profile of 4 strains of ER, Gardel and Senegal, two distant virulent strains with their corresponding attenuated strains. Our results showed a higher metabolic activity in attenuated strains compared to virulent strains, suggesting a better adaptation in vitro of attenuated strains to the host cells. There was a strong modification of membrane protein encoding genes expression for the 4 strains. A major over-expression of map1-related genes was observed for virulent strains, whereas attenuated strains over-expressed genes encoding for hypothetical membrane proteins. This result suggests that in vivo, MAP-1 related proteins could induce non-protective immune responses for virulent strains. For the attenuated strains, the lack of expression of map1-related genes and over-expression of other membrane proteins encoding genes could be important in induction of efficient immune responses.The diminution of expression of many genes in attenuated Senegal was caused by severe mutation. One of them, the gene recO is involved in DNA repair and its mutation could explain the higher proportion of mutated genes in attenuated Senegal, inducing the faster attenuation of Senegal compared to Gardel.
Project description:Multidrug-resistant (MDR; resistance to >3 antimicrobial classes) Salmonella enterica serovar I 4,[5],12:i:- strains were linked to a 2015 foodborne outbreak from pork. Strain USDA15WA-1, associated with the outbreak, harbors an MDR module and the metal tolerance element Salmonella Genomic Island 4 (SGI-4). Characterization of SGI-4 revealed that conjugational transfer of SGI-4 resulted in the mobile genetic element (MGE) replicating as a plasmid or integrating into the chromosome. Tolerance to copper, arsenic, and antimony compounds was increased in Salmonella strains containing SGI-4 compared to strains lacking the MGE. Following Salmonella exposure to copper, RNA-seq transcriptional analysis demonstrated significant differential expression of diverse genes and pathways, including induction of numerous metal tolerance genes (copper, arsenic, silver, and mercury). Evaluation of swine administered elevated concentrations of zinc oxide (2,000 mg/kg) and copper sulfate (200 mg/kg) as an antimicrobial feed additive (Zn+Cu) in their diet for 4 weeks prior to and 3 weeks post-inoculation with serovar I 4,[5],12:i:- indicated that Salmonella shedding levels declined at a slower rate in pigs receiving in-feed Zn+Cu compared to control pigs (no Zn+Cu). The presence of metal tolerance genes in MDR Salmonella serovar I 4,[5],12:i:- may provide benefits for environmental survival or swine colonization in metal-containing settings.
Project description:RNA-sequencing of two Salmonella enterica strains (WT, ∆yebEFG) in standard laboratory conditions (LB to ESP), and in SOS-response inducing conditions (LB+nalidixic acid)
Project description:In this study, we have defined the NsrR regulon in Salmonella enterica sv. Typhimurium 14028s using a transcriptional microarray. Wild-type and nsrR mutant S. Typhimurium were grown aerobically to early log-phase (OD600~0.5) at 37C in LB medium. Total RNA was isolated from three independent cultures of both strains and interrogated on a PCR product array representing almost all ORFs.
Project description:<p>The study of antimicrobial resistance (AMR) in infectious diarrhea has generally been limited to cultivation, antimicrobial susceptibility testing and targeted PCR assays. When individual strains of significance are identified, whole genome shotgun (WGS) sequencing of important clones and clades is performed. Genes that encode resistance to antibiotics have been detected in environmental, insect, human and animal metagenomes and are known as "resistomes". While metagenomic datasets have been mined to characterize the healthy human gut resistome in the Human Microbiome Project and MetaHIT and in a Yanomani Amerindian cohort, directed metagenomic sequencing has not been used to examine the epidemiology of AMR. Especially in developing countries where sanitation is poor, diarrhea and enteric pathogens likely serve to disseminate antibiotic resistance elements of clinical significance. Unregulated use of antibiotics further exacerbates the problem by selection for acquisition of resistance. This is exemplified by recent reports of multiple antibiotic resistance in Shigella strains in India, in Escherichia coli in India and Pakistan, and in nontyphoidal Salmonella (NTS) in South-East Asia. We propose to use deep metagenomic sequencing and genome level assembly to study the epidemiology of AMR in stools of children suffering from diarrhea. Here the epidemiology component will be surveillance and analysis of the microbial composition (to the bacterial species/strain level where possible) and its constituent antimicrobial resistance genetic elements (such as plasmids, integrons, transposons and other mobile genetic elements, or MGEs) in samples from a cohort where diarrhea is prevalent and antibiotic exposure is endemic. The goal will be to assess whether consortia of specific mobile antimicrobial resistance elements associate with species/strains and whether their presence is enhanced or amplified in diarrheal microbiomes and in the presence of antibiotic exposure. This work could potentially identify clonal complexes of organisms and MGEs with enhanced resistance and the potential to transfer this resistance to other enteric pathogens.</p> <p>We have performed WGS, metagenomic assembly and gene/protein mapping to examine and characterize the types of AMR genes and transfer elements (transposons, integrons, bacteriophage, plasmids) and their distribution in bacterial species and strains assembled from DNA isolated from diarrheal and non-diarrheal stools. The samples were acquired from a cohort of pediatric patients and controls from Colombia, South America where antibiotic use is prevalent. As a control, the distribution and abundance of AMR genes can be compared to published studies where resistome gene lists from healthy cohort sequences were compiled. Our approach is more epidemiologic in nature, as we plan to identify and catalogue antimicrobial elements on MGEs capable of spread through a local population and further we will, where possible, link mobile antimicrobial resistance elements with specific strains within the population.</p>
Project description:SrfJ is an effector of the type III secretion systems of the Gram-negative intracellular pathogen Salmonella enterica serovar Typhimurium. To study the effects of this effector on global gene expression in host cells, we have infected murine RAW264.7 macrophages with two strains of Salmonella enterica serovar Typhimurium. The comparison between cells infected with the wild-type strain and cells infected with a srfJ mutant revealed a number of genes that are differentially expressed when SrfJ is present.