Project description:The mechanisms of action of common food preservatives are poorly understood. As there is a drive to develop alternative preservatives, understanding the mechanisms of action of current preservatives can inform development of novel food preservatives to ensure their efficacy. Here we used TraDIS-Xpress, a large-scale, genome-wide unbiased screen to determine the mechanisms of action of common food preservatives by determining the genes that affect preservative susceptibility in Salmonella enterica serovar Typhimurium.
Project description:Antimicrobials have been shown to select for changes in biofilm formation and multidrug susceptibility in common human pathogens. We investigated whether common food preservatives selected for these changes in the food pathogen Salmonella enterica serovar Typhimurium. Bacteria were exposed to four food preservatives in either planktonic cultures or biofilms grown on stainless steel beads. Cultures were passaged into fresh media supplemented with the food preservative every 72 hours. Following approximately 1000 generations of continuous preservative exposure, populations were sequenced to determine the single nucleotide polymorphisms that were selected for over evolutionary time.
Project description:The gene expression of Salmonella enterica Typhimurium MB282 residing in the food vacuole (phagosome) of Tetrahymena was analyzed by microarray.
Project description:Salmonella enterica serovar Typhimurium is a gram-negative bacterium that can colonize the gut of humans and several species of food producing farm animals to cause enteric or septicaemic salmonellosis. Besides compromising public health and food safety, sub-clinical salmonellosis is also believed to be a major problem affecting the profitability of the pig industry. Distinct responses to Salmonella infection have been observed in pigs, some recovering faster and shedding lower levels of Salmonella in faeces than others (low shedders, LS versus persistent shedders, PS). This trait variation could indicate the existence of a genetic component to Salmonella shedding and resistance that may be exploited in animal breeding and disease diagnostics. The study aimed to characterize changes in miRNA expression in response to Salmonella infection.
Project description:Salmonella enterica serovar Typhimurium is a gram-negative bacterium that can colonize the gut of humans and several species of food producing farm animals to cause enteric or septicaemic salmonellosis. Besides compromising public health and food safety, sub-clinical salmonellosis is also believed to be a major problem affecting the profitability of the pig industry. Distinct responses to Salmonella infection have been observed in pigs, some recovering faster and shedding lower levels of Salmonella in faeces than others (low shedders, LS versus persistent shedders, PS). This trait variation could indicate the existence of a genetic component to Salmonella shedding and resistance that may be exploited in animal breeding and disease diagnostics. The study aimed to identify porcine genes and gene co-expression networks that differentiate distinct responses to Salmonella challenge with respect to faecal Salmonella shedding.
Project description:Many non-typhoidal serovars of Salmonella such as Salmonella enterica serovar Typhimurium (S. Typhimurium) are the leading cause of food-borne gastroenteritis, resulting in millions of infections each year and sometimes death. Salmonella enterica serovar Typhimurium is the most common non-typhoidal Salmonella strain isolated from patients around the world and is used as a mouse model to study bacterial pathogenesis and host-microbe interactions. Furthermore, S. Typhimurium is an important pathogen in livestock animals including chickens and cattle. S. Typhimurium utilises a multitude of virulence factors to reach and invade host cells and for its intracellular survival. However, little is known about the mechanism of protein synthesis of these virulence factors at the codon level. Here, we performed RNA-seq and ribosome profiling. Ribosome profiling allows the global mapping of translating ribosomes on the transcriptome and therefore provides direct measure of protein synthesis.
Project description:Salmonella enterica serovar Agona (S. Agona) is a foodborne pathogen that caused recurrent multistate outbreaks associated with cereal between 1998 and 2008, underscoring the endurance of Salmonella over time in low-moisture food (LMF) processing facilities. In this study, we aimed to determine the molecular mechanism of survival of S. Agona in LMF and confirm their impact on phenotype by the knockout study. S. Agona strain (CFSAN 000477), isolated from cereal, was selected for this study. A 100µl suspension with a concentration of ~10^11 cfu/ml was inoculated into 3g of rice cereals. Three replications of inoculated cereals were subjected to desiccation stress (aw ≤ 0.25) for 24h at room temperature (25⁰C). Inoculated cereal samples were collected at 6 timepoints post-inoculation. Cells were separated from the food matrix for RNA extraction. RNA sequencing was performed using the NextSeq 2000 platform. Read counts were generated with Salmon v1.9.0. Downstream analysis was conducted with R and KEGG mapper. There were 1120 differentially expressed genes (DEGs) in S. Agona in response to desiccation stress (Padj < 0.01, |log2FoldChange| >1), with 647 downregulated and 473 upregulated. Functional analysis of downregulated DEGs revealed that most of the genes were associated with metabolic pathways, followed by translation, suggesting slower growth in the surviving population. The top 3 upregulated genes/operons: kdp and ccm operon, and tisB were knocked out and checked for survival study. Approximately 1-2 log reduction (p>0.05) was noticed in the survival of the mutants compared with the wild type. This transcriptome data suggests that Salmonella Agona survives in low-moisture food by conserving energy, lowering metabolism, and reducing replication.