Project description:Spores of Bacillales and Clostridiales species contain 100s of different mRNAs, and their major function in Bacillus subtilis is to provide ribonucleotides for new RNA synthesis when spores germinate. In new work, RNA was isolated from spores of five Bacillales and one Clostridioides species and relative spore mRNA levels were determined by RNA-seq. Determination of RNA levels in single spores allowed calculation of RNA nt/spore, and assuming mRNA is 3% of spore RNA allowed calculation that only ~6% of spore mRNAs were present at ≥ 1/spore. Bacillus subtilis, Bacillus atrophaeus and Clostridioides difficile spores had 49, 42 and 51 mRNAs at >1/spore, respectively. Numbers of mRNAs at ≥1/spore were ~10 to 50% higher in Geobacillus stearothermophilus and Bacillus thuringiensis Al Hakam spores, respectively, and ~ 4-fold higher in Bacillus megaterium spores. Notably, in all species: i) many of the 60 most abundant spore mRNAs were transcribed by RNA polymerase with forespore-specific s factors; ii) some to many of the most abundant spore mRNAs encoded orthologs of those encoded by abundant B. subtilis spore mRNAs and proteins present in dormant spores ; and iii) some spore mRNAs were likely transcribed in the mother cell compartment of the sporulating cell. Indeed , analysis of the coverage of RNA-seq reads on mRNAs from all six species suggested that abundant spore mRNAs were at least somewhat fragmented. This observation was confirmed by RT-qPCR analysis of three abundant mRNAs each from B. subtilis and C. difficile spores. These data add to a growing body of evidence indicating that the great majority of mRNAs in spores of Firmicutes are degradation and function as a ribonucleotide depot for new RNA synthesis when spores germinate.
Project description:Heat-treated spores show delayed and slower germination and outgrowth compared to untreated spores presumably due to spore damage repair. This study was performed to identify genes possibly involved in spore damage repair in B. cereus. In this study we compared the transcriptomic profiles of untreated and heat-treated spores during germination and outgrowth in BHI at 30C.
Project description:Bacterial spores play an important role in disease initiation, transmission and persistence. The outermost spore layer, the exosporium, is important as it is the first point of contact between the spore and the environment and may be involved in spore adherence, protection and germination. Clostridium sordellii is a highly lethal, spore forming pathogen that causes soft-tissue infections, enteritis and toxic-shock syndrome. Despite the importance of C. sordellii spores in disease, spore proteins from this bacterium have not been defined or interrogated functionally. In this study, we identified the C. sordellii outer spore proteome and two of the identified proteins, CSA and CSB, were characterised using a genetic and phenotypic approach. Both proteins were essential for the correct formation and positioning of the C. sordellii spore coat and exosporium. The absence of CSA reduced sporulation levels and increased spore sensitivity to heat, sodium hydroxide and hydrochloric acid. By comparison, CSB was required for normal levels of spore adherence to cervical, but not vaginal, cells, with csb mutant spores having increased adherence properties. The establishment of a mouse infection model of the gastrointestinal tract for C. sordellii allowed the role of CSA and CSB to be interrogated in an infected host. Following the oral administration of spores to mice, the wild-type strain efficiently colonized the gastrointestinal tract, with the peak of bacterial numbers occurring at one day post-infection. Colonization was reduced by two logs at four days post-infection. By comparison, mice infected with the csb mutant did not show a reduction in bacterial numbers. The absence of CSB therefore allows the csb mutant to persist within the gastrointestinal tract. We conclude that C. sordellii outer spore proteins are important for the structural and functional integrity of spores, and for colonization and persistence during infection. Finally, Clostridium difficile, Bacillus cereus and Bacillus anthracis encode proteins with homology to CSA and CSB but these bacteria produce spores that are structurally dissimilar to those of C. sordellii, and the function of the proteins in these hosts is different to that in C. sordellii. These findings suggest that, despite their homology, spore proteins can have variable functions in different bacterial species which highlights the necessity of studying each spore protein in the cognate species from which it originates.
Project description:Rhizopus delemar is an invasive fungal pathogen, responsible for the frequently fatal disease mucormycosis. Germination, a crucial mechanism by which spores of Rhizopus delemar infect and cause disease, is a key developmental process that transforms the dormant spore state into a vegetative one. Understanding the molecular mechanisms which underpin this transformation may be key to controlling mucormycosis; however, the regulation of germination remains poorly understood. This study describes the transcriptional changes which take place over the course of germination.
Project description:Using RNA-seq, we cataloged messenger RNAs in highly purified dormant Bacillus subtilis spores prepared either on plates or in liquid. Almost all of the most abundant spore mRNAs are encoded by genes expressed only in the developing spore late in sporulation under control of the forespore-specific RNA polymerase sigma factor, sG. Given the levels of the ~40 most abundant mRNAs in dormant spores, we calculated the great majority of the low abundance mRNAs can be present in only a small fraction of the spore population.
Project description:Moorella thermoacetica spores are the most heat-resistant so far retrieved in food industry and we previously showed that the resistance properties of these spores to wet- heat and biocides were lower when spores were produced at low limit temperature than at optimal temperature. By electron microcopy, we observed that the ultrastructure of the spore coat differed according to the sporulation temperature, with spores produced at 55 °C mainly exhibiting lamellar inner coat tightly associated to diffuse outer coat, while spores produced at 45 °C showing an inner and outer coat separated by a less electron- dense zone. Moreover, misarranged coat structures were more frequently observed when spores were produced at low limit temperature. We analyzed the proteome of spore ob- tained at 45° and 55 °C and focused our data analysis on putative spore coat, exosporium proteins or proteins playing a role in spore resistance. Some putative spore coat proteins, such as CotSA, were only identified in spores produced at 55 °C, while some other puta- tive exosporium and coat proteins were significantly less abundant in spores produced at 45 °C. Altogether, our results suggest that sporulation temperature affects the structure and the protein composition of M. thermoacetica spores.
Project description:Bacillus subtilis forms dormant spores upon nutrient depletion. Under favorable environmental conditions, the spore breaks its dormancy and resumes growth in a process called spore germination and outgrowth. To elucidate the physiological processes that occur during the transition of the dormant spore to an actively growing vegetative cell, we studied this process in a time-dependent manner by a combination of microscopy, analysis of extracellular metabolites and a genome-wide analysis of transcription. The results indicate the presence of abundant levels of late sporulation transcripts in dormant spores. In addition, results suggest the existence of a complex and well-regulated spore outgrowth program, involving the temporal expression of at least 30 % of the B. subtilis genome. Keywords: time course, spore outgrowth
Project description:This SuperSeries is composed of the following subset Series: GSE36224: Comparison of transcript abundance in aerial mycelium of the Magnaporthe oryzae TRA1-deleted mutant and its parental strain GSE36225: Comparison of transcript abundance in ungerminated spores of the Magnaporthe oryzae TRA1-deleted mutant and its parental strain Refer to individual Series