Project description:Transcriptomics analysis of biopolymer (medium chain length polyhydroxyalkanoate) producing strain P.putida LS46 cultured with biodiesel derived waste carbon sources: studies of cellular adaptation to the industrial waste streams and metabolic profiling under the polymer producing conditions. We are reporting RNAseq analysis data here as part of our multi-level Omics study of medium chain length polyhydroxyalkanoate (mcl-PHA) producing strain P.putida LS46 culture with biodiesel derived waste glycerol and waste fatty acids. The data presented here will be used in two separate manuscripts. The objectives of this study are a): to evaluate cellular responses of P.putida LS46 under industrial waste stream. b): to study gene expression profile under two selected mcl-PHA producing conditions of P.putida LS46. Comparative multi-level Omics study: for objective a): Exponential P.putida LS46 cell from waste glycerol culture compared against reagent grade pure glycerol culture. For objective b): Two mcl-PHA producing conditions, namely stationary phase waste glycerol culture and exponential phase waste fatty acid culture of P.putida LS46, were compared against exponential phase waste glycerol culture of P.putida LS46. Major results from objective a): The waste glycerol substrate induced expression of a large number of genes putatively involved in heavy metal tolerance, including three gene clusters: a putative cusABC transcript unit and two copies of copAB, which are usually involved in copper resistance and tolerance to other monovalent heavy metals. A local gene relocation was observed in cluster 1 consisting cusABC and copAB relative to the KT2440 type strain according to the phylogenetic and gene neighbourhood analyses on various P. putida strains. P. putida LS46 also contains 11 putative MerR family regulators, which sense various environmental stimuli including heavy metals. MerR-1 is an ortholog of the copper response regulator of other gram-negative bacteria, and was highly up-regulated in waste glycerol cultures. Finally, a number of genes involved in cell responses to high extra-cellular Na+ concentrations, and genes of the fatty acid beta-oxidation pathway were up-regulated in waste glycerol cultures Major results from objective b): Regardless to the type of substrates, up-regulation of two mcl-PHA synthase (PhaC1 and PhaC2), and two phasin proteins (PhaF and PhaI) are the most common genotype under mcl-PHA production conditions. PhaG and possible PhaJ4 connect fatty acid de novo synthesis to mcl-PHA in waste glycerol culture. Interestingly, expression of gene, fabZ, in production of unsaturated fatty acid from fatty acid de novo synthesis was only observed in waste glycerol culture. On the other hand, PhaJ1 and PhaJ4 derived mcl-PHA production via fatty acid beta-oxidation was observed under waste fatty acid culture. These results would help to explain observed different production kinetics and monomer distribution of the polymer. Although under active mcl-PHA production condition, depression on the expression of glpF genes in glycerol transportation system prevent further channelling extra-cellular glycerol into the cell. Waste glycerol culture also triggers trahalose synthesis pathway, a potential competing pathway during mcl-PHA synthesizing. In waste fatty acid culture, the intermediates (acyl-CoA and 3-hydroxyacyl-CoA) of fatty acid beta-oxidation were used for mcl-PHA production and were also likely hydrolysed to their free acid forms via an up-regulated thioesteras coding gene, tesA. Acetyl-CoA cleaved from the pathway was clearly channeled into glyoxylate shut for C2 carbon assimilation over spillage as CO2 through TCA cycle or used in fatty acid biosynthesis pathway.
Project description:Transcriptomics analysis of biopolymer (medium chain length polyhydroxyalkanoate) producing strain P.putida LS46 cultured with biodiesel derived waste carbon sources: studies of cellular adaptation to the industrial waste streams and metabolic profiling under the polymer producing conditions. We are reporting RNAseq analysis data here as part of our multi-level Omics study of medium chain length polyhydroxyalkanoate (mcl-PHA) producing strain P.putida LS46 culture with biodiesel derived waste glycerol and waste fatty acids. The data presented here will be used in two separate manuscripts. The objectives of this study are a): to evaluate cellular responses of P.putida LS46 under industrial waste stream. b): to study gene expression profile under two selected mcl-PHA producing conditions of P.putida LS46. Comparative multi-level Omics study: for objective a): Exponential P.putida LS46 cell from waste glycerol culture compared against reagent grade pure glycerol culture. For objective b): Two mcl-PHA producing conditions, namely stationary phase waste glycerol culture and exponential phase waste fatty acid culture of P.putida LS46, were compared against exponential phase waste glycerol culture of P.putida LS46. Major results from objective a): The waste glycerol substrate induced expression of a large number of genes putatively involved in heavy metal tolerance, including three gene clusters: a putative cusABC transcript unit and two copies of copAB, which are usually involved in copper resistance and tolerance to other monovalent heavy metals. A local gene relocation was observed in cluster 1 consisting cusABC and copAB relative to the KT2440 type strain according to the phylogenetic and gene neighbourhood analyses on various P. putida strains. P. putida LS46 also contains 11 putative MerR family regulators, which sense various environmental stimuli including heavy metals. MerR-1 is an ortholog of the copper response regulator of other gram-negative bacteria, and was highly up-regulated in waste glycerol cultures. Finally, a number of genes involved in cell responses to high extra-cellular Na+ concentrations, and genes of the fatty acid beta-oxidation pathway were up-regulated in waste glycerol cultures Major results from objective b): Regardless to the type of substrates, up-regulation of two mcl-PHA synthase (PhaC1 and PhaC2), and two phasin proteins (PhaF and PhaI) are the most common genotype under mcl-PHA production conditions. PhaG and possible PhaJ4 connect fatty acid de novo synthesis to mcl-PHA in waste glycerol culture. Interestingly, expression of gene, fabZ, in production of unsaturated fatty acid from fatty acid de novo synthesis was only observed in waste glycerol culture. On the other hand, PhaJ1 and PhaJ4 derived mcl-PHA production via fatty acid beta-oxidation was observed under waste fatty acid culture. These results would help to explain observed different production kinetics and monomer distribution of the polymer. Although under active mcl-PHA production condition, depression on the expression of glpF genes in glycerol transportation system prevent further channelling extra-cellular glycerol into the cell. Waste glycerol culture also triggers trahalose synthesis pathway, a potential competing pathway during mcl-PHA synthesizing. In waste fatty acid culture, the intermediates (acyl-CoA and 3-hydroxyacyl-CoA) of fatty acid beta-oxidation were used for mcl-PHA production and were also likely hydrolysed to their free acid forms via an up-regulated thioesteras coding gene, tesA. Acetyl-CoA cleaved from the pathway was clearly channeled into glyoxylate shut for C2 carbon assimilation over spillage as CO2 through TCA cycle or used in fatty acid biosynthesis pathway. In total 4 sampling points, namely exponential phase of pure glycerol, waste glycerol and waste free fatty acids cultures, and stationary phase of waste glycerol culture. For each sampling point, 2 biological replicates were taken. (Thus 8 samples in total)
Project description:Clostridium sp. strain CT7 is a new emerging microbial cell factory with high butanol ratio owing to the non-traditional butanol fermentation mode with uncoupled acetone and 1,3-propanediol formation. Significant change of products profile was shown in glycerol- and glucose-fed strain CT7, especially much higher butanol and lower volatile fatty acids production from glycerol-fed one. However, the mechanism of this interesting phenomenon was still unclear. To better elaborate the bacterial response towards glycerol and glucose, the quantitative proteomic analysis through iTRAQ strategy was performed to reveal the regulated proteomic expression levels under different substrates. Proteomics data showed highly increased proteomic expression levels of proteins related with glycerol utilization and solvent generation under glycerol media. In addition, the up-regulation of hydrogenases, ferredoxins and electron-transferring proteins may attribute to the internal redox balance, while the earlier triggered sporulation response in glycerol-fed media may be associated with the higher butanol fermentation. This study will provide the platform for metabolic engineering of this emerging industrial microorganism for more efficient butanol production from glycerol.
Project description:Biotechnology suggests that microorganisms can be used as chemical factories that transform renewable feedstock into value-added chemicals. Conversion of glycerol, using direct transformation or fermentation, into valuable products such as polymers, surfactants, solvents, and chemical intermediates has attained growing interest in recent years due to the dramatic growth of the biodiesel industry. However, the use of cell factories could be limited by low growth and uptake rates under certain environmental conditions, thus understanding microbial nutritional requirements is a critical point to use them as cell factories. Here, we compared E. coli ATCC 8739 transcriptomic responses to glycerol under aerobic conditions in an optimized culture medium (Condition 3) and one evolved strain in glycerol using as a reference a glycerol-based medium (Condition 11). Our analyses revealed 478 and 431 differentially expressed genes (DEGs) with log2 fold change (FC) > |2| and p Adjusted value < 0.05, for the bacteria growing in the optimized culture medium and the evolved strain, respectively. Among the DEGs, glp operon was found to be up-regulated as a response to glycerol uptake. Interestingly, between them, it was found genes that requires the use of phosphorous to ovoid the toxicity during glycerol consumption. Previously, we identified using a computational approach that phosphorous and nitrogen are essential compound that support high glycerol consumption in E. coli.
Project description:Glycerol offers several advantages as a substrate for biotechnological applications. An important step towards using the popular production host Saccharomyces cerevisiae for glycerol-based bioprocesses have been recent studies in which commonly used S. cerevisiae strains were engineered to grow in synthetic medium containing glycerol as the sole carbon source. In order to boost extensive S. cerevisiae metabolic engineering incentives aiming at the use of glycerol, we realized that promoters with predictable expression levels in synthetic glycerol medium were required. In the current study, we used transcriptome analysis and a yECitrine-based fluorescence reporter assay to select and characterize useful 25 promoters for driving expression of target genes in S. cerevisiae under the given conditions. The promoters of the genes ALD4 and ADH2 showed 4.2- and 3-fold higher activities compared to the well-known strong TEF1 promoter. Moreover, the collection contains promoters with graded activities in synthetic glycerol medium and different degrees of glucose repression. To demonstrate the general applicability of the promoter collection, we successfully used a subset of the characterized promoters with graded activities in order to optimize growth on glycerol in an engineered derivative of CEN.PK, in which glycerol catabolism exclusively occurs via a non-native DHA pathway.
Project description:The rainbow smelt (Osmerus mordax, Mitchill, 1814) is an anadromous teleost that overwinters in the estuaries and inshore waters along the North American Atlantic coastline. In the winter months, smelt avoid freezing in subzero temperatures by the production of antifreeze proteins and high levels of glycerol. Glycerol production (glyceroneogenesis) occurs in the liver via a branch point in glycolysis and gluconeogenesis and is directly activated by low temperature. In these studies, hepatocytes were isolated from the liver of individual warm fish and incubated at either a warm (8ºC; non-glycerol accumulating) or cold (0.4ºC; glycerol accumulating) temperature over a 72 h time course. Functional genomic techniques were used to identify and validate hepatic transcripts that were differentially expressed between the warm and cold cells. Reciprocal suppression subtractive hybridization (SSH) cDNA libraries enriched for cold-responsive liver transcripts were constructed at the 72 h incubation time. Microarray analyses using the consortium for Genomic Research on All Salmonids Project (cGRASP) 16K (salmonid) cDNA array were performed at the 24, 48 and 72 h incubation times. For quantitative reverse transcription – polymerase chain reaction (QPCR) studies, we focused specifically on the non-colligative [type II antifreeze protein (AFPII)] and colligative (glycerol accumulation) freeze prevention strategies. AFPII (SSH identified) and 21 transcripts (SSH and/or microarray identified or selected by the authors based on a conceptual link to glycerol production) involved in the metabolism of glycolytic (glycogen, glucose) and gluconeogenic (amino acids) sources of glycerol and of lipids with a glycerol backbone (triglyceride, phosphoplipid) were analyzed using QPCR.
Project description:Lactobacillus reuteri is a heterofermentative lactic acid bacterium best known for its ability to co-ferment glucose and glycerol. Its genome sequence has recently been deduced enabling the implementation of genome-wide analysis. In this study we developed a dedicated cDNA microarray platform and a genome-scale metabolic network model of L. reuteri and use them to revisit the co-fermentation of glucose and glycerol. The model was used to simulate experimental conditions and to visualize and integrate experimental data in particular the global transcriptional response of L. reuteri to the presence of glycerol. We show how the presence of glycerol affects cell physiology and triggers specific regulatory mechanisms allowing simultaneously a better yield and more efficient biomass formation. Furthermore we were able to predict and demonstrate for this well-studied condition the involvement of previously unsuspected metabolic pathways for instance related to amino acids and vitamins. These could be used as leads in future studies aiming at the increased production of industrially relevant compounds such as vitamin B12 or 1 3- propanediol. Keywords: cell type comparison
Project description:Lactobacillus reuteri is a heterofermentative lactic acid bacterium best known for its ability to co-ferment glucose and glycerol. Its genome sequence has recently been deduced enabling the implementation of genome-wide analysis. In this study we developed a dedicated cDNA microarray platform and a genome-scale metabolic network model of L. reuteri and use them to revisit the co-fermentation of glucose and glycerol. The model was used to simulate experimental conditions and to visualize and integrate experimental data in particular the global transcriptional response of L. reuteri to the presence of glycerol. We show how the presence of glycerol affects cell physiology and triggers specific regulatory mechanisms allowing simultaneously a better yield and more efficient biomass formation. Furthermore we were able to predict and demonstrate for this well-studied condition the involvement of previously unsuspected metabolic pathways for instance related to amino acids and vitamins. These could be used as leads in future studies aiming at the increased production of industrially relevant compounds such as vitamin B12 or 1 3- propanediol. Keywords: cell type comparison