Project description:In this study, we used mass spectrometry-based discovery proteomic analysis to examine the cell-wide changes of Mycobacterium smegmatis, in response to sub-lethal concentrations of H2O2 and nitric oxide (NO) over time. Preliminary results have shown that sub-lethal concentrations of reactive oxygen and nitrogen species may act as signalling molecules by playing a role in the overall protein abundance that may be conducive to survival in vivo. The presented study showed that both treatments induced: the DosR regulon, alterations in protein expression and lipid metabolism. In addition to the proteomic changes observed, we have also observed increased survival after macrophage infection of Mycobacterium smegmatis pre-exposed to sub-lethal doses of H2O2 or DETA-NO. ¬ In total, 27 samples yielded approximately 3300 M. smegmatis protein group identifications. More in-depth analysis of this new dataset will provide a better understanding as to the inner workings of mycobacteria under oxidative and nitrosative stress and potential mechanisms by which exposure to sub-lethal concentrations of stressors results in an increased resistance to stress.
Project description:The study aims essentially in the analysis of the transcriptomic and metabolomic profiles induced by the presence of the tested ionic liquids in the metabolism of Aspergillus nidulans. Focusing specially on the secondary metabolism, which genes are clustered.
Project description:Non-typeable Haemophilus influenzae (NTHi) is a common acute otitis media pathogen, with an incidence that is increased by previous antibiotic treatment. NTHi is also an emerging causative agent of other chronic infections in humans, some linked to morbidity, and all of which impose substantial treatment costs. In this study we explore the possibility that antibiotic exposure may stimulate biofilm formation by NTHi bacteria. We discovered that sub-inhibitory concentrations of beta-lactam antibiotic (i.e., amounts that partially inhibit bacterial growth) stimulated the biofilm-forming ability of NTHi strains, an effect that was strain and antibiotic dependent. When exposed to sub-inhibitory concentrations of beta-lactam antibiotics NTHi strains produced tightly packed biofilms with decreased numbers of culturable bacteria but increased biomass. The ratio of protein per unit weight of biofilm decreased as a result of antibiotic exposure. Antibiotic-stimulated biofilms had altered ultrastructure, and genes involved in glycogen production and transporter function were up regulated in response to antibiotic exposure. Down-regulated genes were linked to multiple metabolic processes but not those involved in stress response. Antibiotic-stimulated biofilm bacteria were more resistant to a lethal dose (10M-BM-5g/mL) of cefuroxime. Our results suggest that beta-lactam antibiotic exposure may act as a signaling molecule that promotes transformation into the biofilm phenotype. Loss of viable bacteria, increase in biofilm biomass and decreased protein production coupled with a concomitant up-regulation of genes involved with glycogen production might result in a biofilm of sessile, metabolically inactive bacteria sustained by stored glycogen. These biofilms may protect surviving bacteria from subsequent antibiotic challenges, and act as a reservoir of viable bacteria once antibiotic exposure has ended. 12 samples
Project description:Non-typeable Haemophilus influenzae (NTHi) is a common acute otitis media pathogen, with an incidence that is increased by previous antibiotic treatment. NTHi is also an emerging causative agent of other chronic infections in humans, some linked to morbidity, and all of which impose substantial treatment costs. In this study we explore the possibility that antibiotic exposure may stimulate biofilm formation by NTHi bacteria. We discovered that sub-inhibitory concentrations of beta-lactam antibiotic (i.e., amounts that partially inhibit bacterial growth) stimulated the biofilm-forming ability of NTHi strains, an effect that was strain and antibiotic dependent. When exposed to sub-inhibitory concentrations of beta-lactam antibiotics NTHi strains produced tightly packed biofilms with decreased numbers of culturable bacteria but increased biomass. The ratio of protein per unit weight of biofilm decreased as a result of antibiotic exposure. Antibiotic-stimulated biofilms had altered ultrastructure, and genes involved in glycogen production and transporter function were up regulated in response to antibiotic exposure. Down-regulated genes were linked to multiple metabolic processes but not those involved in stress response. Antibiotic-stimulated biofilm bacteria were more resistant to a lethal dose (10µg/mL) of cefuroxime. Our results suggest that beta-lactam antibiotic exposure may act as a signaling molecule that promotes transformation into the biofilm phenotype. Loss of viable bacteria, increase in biofilm biomass and decreased protein production coupled with a concomitant up-regulation of genes involved with glycogen production might result in a biofilm of sessile, metabolically inactive bacteria sustained by stored glycogen. These biofilms may protect surviving bacteria from subsequent antibiotic challenges, and act as a reservoir of viable bacteria once antibiotic exposure has ended.
Project description:Stress survival tactics in bacteria utilize the up- and down-regulation of stress response genes. In bacteria that lack classical stress response genes for oxidative stress, other cellular systems can be used for cell survival. We used custom microarrays to study the regulation of genes in Bifidobacterium animalis ssp. lactis strains to oxidative stress to elucidate novel stress response mechanisms. Bifidobacterium cells were grown to late log phase then harvested and exposed to a sub-lethal level of hydrogen peroxide. Samples were taken at 5 and 20 mins for RNA extraction and hybridization on Affymetrix microarrays. Controls were prepared for each time point which recieved no hydrogen peroxide treatment.
Project description:We have analyzed the genome-wide redistribution of RNA polymerase in E.coli upon methylglyoxal stress. Herefore, we have used ChIP-chip against the beta subunit of RNA polymerase and we have assessed changes in RNA polymerase distribution upon sub-lethal and lethal concentrations of methylglyoxal.
Project description:This project aimed to investigate the effects of glyphosate-based herbicide Roundup LB Plus on bacteria. For this, ten environmental strains of Salmonella enterica were exposed to the increasing concentrations of Roundup over several passages to obtain Roundup-resistant mutants. Four stable re-sequenced resistant mutants and their respective ancestors were characterized by global proteomics in the presence and absence of sub-inhibitory (1/4xMIC) concentrations of the herbicide. By comparing the proteomes of the Roundup-challenged ancestors with constitutive non-challenged ancestors, it became possible to deepen the understanding of how Roundup stress affects naïve bacteria. Similarly, comparing Mutants versus Ancestors in the absence of Roundup allowed to understand how Roundup resistance constitutively affects bacterial physiology, while the comparison of Roundup-challenged mutants versus constitutive mutants helped improve the understanding of the inducible responses in the resistant background.
Project description:This study investigates transcriptional responses of the springtail Folsomia candida to two relevant concentrations of diclofenac A direct design was used where springtails were exposed to 3two concentrations of diclofenac (EC10 and EC50 on reproduction) and microarrays were directly contrased to those from animals exposed to clean LUFA2.2 soil. 4 biological replicates were used with each containing 25 grams of soil and 30 adult, randomly selected, age sychronized springtails