Deciphering the transcriptional adaptation of Corynebacterium glutamicum in transition from aerobiosis via microaerobiosis to anaerobiosis via RNA-seq
ABSTRACT: To investigate the adaptation of Corynebacterium glutamicum to altering oxygen availabilities, we conceived a triple-phase fermentation process that describes a gradual reduction of dissolved oxygen depicting a shift from aerobiosis via microaerobiosis to anaerobiosis. The distinct process phases were clearly bordered by the bacteria’s physiologic response such as reduced growth rate, biomass substrate yield and altered yield of fermentation products. During the process, sequential samples were drawn at six points and analyzed via RNA-sequencing of Illumina TruSeq Stranded mRNA libaries sequenced paired end on an Illumina MiSeq system using 75 nt read length. We found transcriptional alterations of almost 50 % (1421 genes) of the entire protein coding genes and observed an upregulation of fermentative pathways, a rearrangement of respiration and mitigation of the basic cellular mechanisms such as transcription, translation and replication as a transient response related to the installed oxygen dependent process phases.
Project description:By the direct comparison of illuminated and non-illuminated microtiter plate cultures of Streptomyces lividans TK24 transcriptomes, the effects of differing cultivation systems by the relevance of light, a parameter that is usually out of scope during heterotrophic bioprocesses, could be addressed.
Project description:The Saccharomyces cerevisiae SFP1 is required for proper regulation of ribosome biogenesis and cell size in response to nutrients. A mutant deleted for SFP1 shows specific traits among which a slow growth phenotype, which is particularly evident during growth on glucose. To assess the effects of nutrients on the activity of Sfp1 independent by growth rate related feedback we grew an sfp1Δ mutant and its isogenic reference strain in chemostat cultures, at the same specific growth rate, under glucose/ethanol-limitation. Our data show that Sfp1 is involved in the modulation of cell size and RiBi gene expression and that these two functions are differently influenced by nutrients. The continuous cultures were then pulsed with a glucose excess generating a situation of batch growth similar to shake flask cultures. The dynamic analysis of the metabolic and transcriptional response following the glucose addition suggested that Sfp1 plays a role at the crossroads of ribosome biogenesis and central carbon metabolism regulation. Finally, we show that the down-regulation of RP genes, which was observed in an sfp1Δ strain during shake flask growth, cannot be directly ascribed to the absence of Sfp1 but is most probably a secondary effect due to the low growth potential of the mutant strain. Experiment Overall Design: After ten volume changes, few seconds after the samples for the steady state analysis were collected, the anaerobic glucose pulse experiments were started by sparging the medium reservoir and the fermenter with pure nitrogen gas (airflow of 0.5 L min-1, Hoek-Loos, Schiedam, <5 ppm O2). NorpreneTM tubing and butyl septa were used to minimize oxygen diffusion into the anaerobic culture. Two minutes after nitrogen sparging and just before the addition of glucose, the medium and the effluent pumps were switched off. At this time point (which we will refer to as time T=0) the 200 mM glucose pulse was injected aseptically through a rubber septum. Experiment Overall Design: Sampling from chemostats, total RNA extraction, probe preparation and hybridization to Affymetrix Genechip® microarrays were performed as previously described (1). Samples were collected at steady state and then at 5, 10, 30, 60 and 120 minutes after the pulse. The results relative to steady state samples were derived from three independent cultures, those relative to the time course analysis were derived from two independent cultures. Experiment Overall Design: 1) Cipollina C., van den Brink J., Daran-Lapujade P., Pronk J.T., Vai M. and de Winde J.H. (2007) Revisiting the role of yeast Sfp1 in ribosome biogenesis and cell size control: A chemostat study. Microbiology. In press.
Project description:Oxygen and carbon dioxide are common protective gases used in modified atmosphere packaging (MAP) of meat. Within the package, they selectively suppress members of the spoilage microbiome, reshaping it to adapted species concomitantly growing upon MAP. Thus, this species must exhibit adaptation mechanisms to withstand the inhibitory effect of carbon dioxide and oxygen, and cope with selective nutrition on MAP meat. In order to uncover these mechanisms, the typical representative meat-spoiling bacteria Brochothrix (B.) thermosphacta TMW2.2101 and four lactic acid bacteria (LAB) Carnobacterium (C.) divergens TMW2.1577, C. maltaromaticum TMW2.1581, Leuconostoc (L.) gelidum subsp. gelidum TMW2.1618 and L. gelidum subsp. gasicomitatum TMW2.1619 were grown in a meat simulation medium under a controlled, sterile environment, aerated constantly with either air, 100%_N2, 30%_CO2/70%_O2 or 30%_CO2/70%_N2. Growth dynamics were monitored and a label-free quantitative mass spectrometric approach was employed to determine changes within the bacterial proteomes in response to the different gas atmospheres. Revealed bacterial tolerance to modified atmospheres (MA) comprise two possible scenarios: Either bacteria were intrinsically adapted to MA, exhibiting no proteomic regulation of enzymes (L. gelidum subsp. gelidum and gasicomitatum) or, tolerance was provided by varying specific metabolic adaptation (B. thermosphacta, C. divergens, C. maltaromaticum). In detail, metabolic adaptation mechanisms to oxygen comprised an enhanced oxidative stress reduction response, adjustment of the pyruvate metabolism and catabolic oxygen consuming reactions. Adaptation to carbon dioxide was characterized by an upregulation of proteins involved in intracellular pH homeostasis, maintenance of osmotic balance and alteration of the fatty acid composition of the cell membrane. We furthermore predict species-specific strategies for different and preferential carbon source utilization enabling a non-competitive coexistence on meat and resulting in a synergistic spoilage. We conclude that a gas atmosphere containing 30%_CO2/70%_O2 has no inhibitory effect on the analyzed prominent meat-spoiling bacteria whereas 30%_CO2/70%_N2 predictively inhibits C. divergens TMW21577 and B. thermosphacta TMW2.2101 but not the other three species. This gives a mechanistically explanation of their acknowledged status as typical spoilage organisms on packaged meats.
Project description:In this study, we focused on chemically defined inducers or substrates to drive expression of cellulases, hemicellulases and accessory enzymes in the model filamentous fungus Aspergillus oryzae. Cellohexaose (O-CHE), mannohexaose (O-MHE), xylopentaose (O-XPE), arabinoheptaose (O-AHP), 1,3:1,4-β-glucohexaose (O-BGHEXA), 63-α-D-glucosyl-maltotriosyl-maltotriose (O-GMH), 61-α-D-galactosyl-mannotriose (O-GM3), xyloglucan (X3Glc4-borohydride reduced; O-X3G4R), turanose (TYR) and sophorose (SOP) were used to induce the plant polysaccharide degradation machinery of A. oryzae. The strain used in this study was the A. oryzae sequenced strain RIB40, obtained from IBT culture collection at Technical University of Denmark. To obtain a global view of the A. oryzae transcriptome activated for plant biomass conversion, mRNA from growth after 2 h on 10 different carbohydrate active enzyme inducers (di- and –oligo saccharides) was subjected to custom-designed Agilent microarray analysis.
Project description:Wild type strain CEN.PK113-7D was grown in an aerobic batch cultivation with a start concentration of 20 g/L galactose. During exponential growth at a biomass concentration of 3 g dry weight/L LiCl was added to a concentration of 10 mM. Just before addition of LiCl (time 0) and 20, 40, 60 and 140 minutes after addition of LiCl samples were taken for transcription analysis. Lithium inhibits phosphoglucomutase whereby both galactose uptake and growth is strongly affected.
Project description:The growth rate (µ) of microbes is a fundamental property influencing its production capacity. To identify the transcriptomic changes of Corynebacterium glutamicum ATCC13032 with increasing growth rate, three transitions, induced by different pre-culture conditions, were sampled in triplicate at growth rates ranging from 0.02 to 0.4 h-1. The pre-culture conditions differed in limiting substrate (phosphate, nitrogen, carbon) and the length of the stationary phase. Samples of 2 mL were withdrawn from the bioreactor in biological triplicates and immediately centrifuged at 20000 g for 30 seconds at 4 °C. The supernatant was discarded and the remaining cell pellet was immediately flash frozen in liquid nitrogen. Total RNA was isolated from three biological replicates using RNeasy Mini Kit along with a DNase Kit (both from Qiagen). Initially RNA quality was checked by Trinean Xpose (Gentbrugge,Belgium) and Agilent RNA Nano 6000 kit on Agilent 2100 Bioanalyzer (Agilent Technologies, Böblingen, Germany). Samples contaminated with DNA were treated with DNase (Qiagen), cleaned as described above and rechecked by Xpose and Agilent Bioanalyzer. Finally RNA was free of DNA with an RNA Integrity Number (RIN) > 9 and rRNA Ratio [23s / 16s] > 1.5. Ribo-Zero rRNA Removal Kit (Bacteria) from Illumina (San Diego, CA, USA) was used to remove the ribosomal RNA molecules from the isolated total RNA. Removal of rRNA was checked by Agilent RNA Pico 6000 kit on Agilent 2100 Bioanalyzer (Agilent Technologies, Böblingen, Germany). RNA was free of detectable rRNA. TruSeq Stranded mRNA Library Prep Kit from Illumina (San Diego, CA, USA) was used to prepare cDNA libraries. The resulting cDNAs were sequenced paired end on an Illumina MiSeq system using 75 bp read length and on Illumina HiSeq 1500 system using 70 bp read length and 50 bp read length for one single sample. Through the comparison of these three datasets, each containing three biological replicates, the pre-condition independent gene expression changes could be deduced and the growth rate modulon was identified.
Project description:High throughput sequencing is a powerful tool to investigate complex cellular phenotypes in functional genomics studies. Sequencing of transcriptional molecules, RNA-seq, has recently become an attractive method of choice in the studies of transcriptomes, promising several advantages compared to traditional expression analysis based on microarrays. In this study, we sought to assess the contribution of the different analytical steps involved in analysis of RNA-seq data and to cross-compare the results with those obtained through a microarray platform. We used the well-characterized Saccharomyces cervevisiae strain CEN.PK 113-7D grown under two different physiological conditions (batch and chemostat) as a case study. In our work, we addressed the influence of genetic variability on the estimation of gene expression level using three different aligners for read-mapping (Gsnap, Stampy and Tophat), the capabilities of five different statistical methods to detect differential gene expression (baySeq, Cuffdiff, DESeq, edgeR and noiSeq) and we explored the consistency between the two main approaches for RNA-seq: reference mapping and de novo assembly. High reproducibility in data generated through RNA-seq among different biological replicates (correlation ≥ 0.99) and high consistency with the results identified with RNA-seq and microarray data analysis (correlation ≥ 0.91) were observed. The results from differential gene expression identification as well as the results of integrated analysis based on the different methods are in good agreement. Overall, our study provides a useful and comprehensive comparison of the workflow for transcriptome analysis using RNA-seq technique. Microarray ananlysis were perfomed from the same RNA extraction then compare the result with RNA-seq analysis
Project description:Here we used microarrays to characterize changes in global gene expression in the hepatopancreas of Pacific white shrimp, Litopenaeus vannamei, exposed to short term (4 h) hypoxia (H) or hypercapnic hypoxia (HH) or long term (24 h) H or HH, compared to animals in air-saturated water (normoxia). The transcriptomes of crustaceans exposed to low O2 and high CO2 contained both shared and treatment-specific signature genes (q ≤ 0.01, FC ≥ 1.5), with shifts characteristic of metabolic depression rather than anaerobic metabolism. Down-regulated signature genes dominated the transcript profile in three of the four treatments (H 4 h, H 24 h, 4 h HH); many of these genes were involved in amino acid or RNA metabolism or in translation, including several tRNA synthetases. Unique patterns of gene expression such as increased lipid metabolism and hemocyanin synthesis (H 24 h) and initiation of apoptosis (24 h HH) were tied to specific treatments. This work contributes insight to the effects that human perturbations might have on estuarine organisms, and the importance of examining the impacts of environmentally relevant combinations of hypoxia and hypercapnia on estuarine populations. L. vannamei were exposed for 4 or 24 hours to one of the following conditions: normoxia, hypoxia or hypercapnic hypoxia. Hepatopancreas tissue from individual animals was dissected, total RNA extracted, labelled and hybridized to oligonucleotide microarrays with probes for 21,864 L. vannamei unigenes. Treatments were repeated until a total of 7 biological replicates was obtained for each time:treatment combination, except for the 24 h normoxia group, represented by 6 replicates.
Project description:Cells usually respond to changing growth conditions with a change in the specific growth rate (μ) and adjustment of their proteome to adapt and maintain metabolic efficiency. Description of the principles behind proteome resource allocation is thus important for understanding metabolic regulation in responce to changing specific growth rate. We analysed the allocation dynamics of Escherichia coli proteome resources into different metabolic processes in response to changing μ. E. coli was grown on minimal and defined rich media in steady state continuous cultures at different μ and characterised by absolute quantitative LC-MS/MS based proteomics. We detected slowly growing cells investing more proteome resources in energy generation and carbohydrate transport and metabolism whereas for achieving faster growth cells needed to devote most resources to translation and processes closely related to the protein synthesis pipeline. Furthermore, down-regulation of energy generation and carbohydrate metabolism proteins with faster growth displayed very similar expression dynamics with the global transcriptional regulator CRP (cyclic AMP receptor protein), pointing to a dominant protein resource allocating role for this protein. Our data also suggest that acetate overflow may be the result of global proteome resource optimisation as cells saved proteome resources by switching from fully respiratory to respiro-fermentative growth. The presented results give a quantitative overview how E. coli adjusts its proteome to achieve faster growthin response to perturbations in μ. Quantitative understanding of proteome resource allocation could contribute to the design of more efficient cell factories through proteome optimisation towards proteins related to target molecule synthesis.
Project description:Expression data for Desulfovibrio alaskensis strain G20 grown on lactate in sulfate-limited monoculture and syntrophic coculture with Methanococcus maripaludis in chemostats at a high growth rate of 0.047h-1 5 replicates of coculture and 3 replicates of sulfate-limited monoculture