Project description:Transcriptome analysis of strains LT-ΔfadE (control) and FRT-ΔfadE (FadR overexpressor) after 12h of fatty acid production. The strains used are described in detail in Zhang F, M Ouellet, TS Batth, CJ Petzold, A Mukhopadhyay and JD Keasling. Enhancing fatty acid production by the expression of the regulatory transcription factor FadR. (In preparation) Three independent cultures of control strain LT-ΔfadE and four independent cultures of FadR overexpressor strain FRT-ΔfadE were induced. One sample derived from each culture was hybridized.
Project description:Transcriptome analysis of strains LT-ΔfadE (control) and FRT-ΔfadE (FadR overexpressor) after 12h of fatty acid production. The strains used are described in detail in Zhang F, M Ouellet, TS Batth, CJ Petzold, A Mukhopadhyay and JD Keasling. Enhancing fatty acid production by the expression of the regulatory transcription factor FadR. (In preparation)
Project description:Microbial physiology plays a pivotal role in construction of a superior microbial cell factory for efficient production of desired products. Here we identified pcnB repression through genome-scale CRISPRi modulation combining fluorescence-activated cell sorting (FACS) and next-generation sequencing (NGS), which confers improved physiology for free fatty acids (FFAs) overproduction in Escherichia coli. The repression of pcnB could improve the stability and abundance of the transcripts involved in proton-consuming system, conferring a global improvement on cell membrane, redox state, and energy level. These physiological advantages facilitated further identification of acrD repression enhancing FFAs efflux. The engineered strain pcnBi-acrDi-fadR+ achieved 35.1 g l−1 FFAs production in fed-batch fermentation, which is the maximum titer in E. coli reported to date. This study underscores the significance of hidden genetic determinants in microbial biosynthesis and sheds light on the role of microbial physiologies in boosting microbial biosynthesis.
Project description:Microbial physiology plays a pivotal role in construction of a superior microbial cell factory for efficient production of desired products. Here we identified pcnB repression through genome-scale CRISPRi modulation combining fluorescence-activated cell sorting (FACS) and next-generation sequencing (NGS), which confers improved physiology for free fatty acids (FFAs) overproduction in Escherichia coli. The repression of pcnB could improve the stability and abundance of the transcripts involved in proton-consuming system, conferring a global improvement on cell membrane, redox state, and energy level. These physiological advantages facilitated further identification of acrD repression enhancing FFAs efflux. The engineered strain pcnBi-acrDi-fadR+ achieved 35.1 g l−1 FFAs production in fed-batch fermentation, which is the maximum titer in E. coli reported to date. This study underscores the significance of hidden genetic determinants in microbial biosynthesis and sheds light on the role of microbial physiologies in boosting microbial biosynthesis.
Project description:The only membrane-anchored and essential ATP-dependent protease in Escherichia coli is FtsH. It controls the intracellular concentration of the deacetylase LpxC, which catalyses the first committed step in lipopolysaccharide biosynthesis. LpxC stability is strictly regulated in a growth rate-dependent manner to ascertain a vital equilibrium of lipopolysaccharide (LPS) and phospholipid biosynthesis. Previous studies suggested the involvement of yet unknown factors in LpxC degradation. Aiming at the identification of such factors that are predicted to be associated with LpxC and/or FtsH at high and low growth rates, we established a quantitative super-SILAC LC-MS/MS-based approach. The identification of known LpxC and FtsH interactors validated our approach. Several enzymes involved in fatty acid biosynthesis and degradation, including the central regulator FadR, interacted with LpxC and/or FtsH and showed a significant impact on LpxC stability. The newly identified LpxC and FtsH interactor WaaH, a LPS-modifying enzyme, stimulates LpxC degradation. Our results go beyond the previously established link between LPS and phospholipid biosynthesis and uncover a far-reaching network that controls LPS biosynthesis by involving multiple enzymes in fatty acid metabolism and phospholipid biosynthesis and modification.
Project description:Purpose: The goals of this study are to find out the differential expression genes in the fadR mutant strain(ΔfadR) compared with wild-type (WT) and to further explore the regulation mechanisms of fadR. Methods: Shewanella oneidensis MR-1 WT and ΔfadR were collected in log phage(OD~0.6). RNA extraction was performed using the RNeasy minikit (Qiagen) and the RNA was quantified by using a NanoVue spectrophotometer (GE Healthcare). RNA seq was performed using Illumina NextSeq 500, 2×150 bp. Results: Our study represents that the expression of 146 genes were decreased and 94 genes were increased inΔfadR compared with WT. Branched-chain keto acid dehydrogenase (BKD) produces corresponding branched-chain acyl coenzyme A which further participating branchend-chain fatty acids synthesis. The expression of bkdA2 was also promoted in △fadR compared with WT. Conclusions: Combined with our expression results, it declared that FadR can suppress bkd operon in some degree,which further increase the synthesis of branched-chain fatty acids in ΔfadR.
Project description:Comparative analysis of changes in gene and protein expression and fatty acid profiles between Escherichia coli K-12 MG1655 ΔfadD ΔaraBAD expressing an acyl-acyl carrier protein thioesterase from Umbellularia californica (BTE) or a non-functional mutant thioesterase (BTE-H204A) to determine the functional basis for losses in cell viability, membrane integrity, or other stresses and metabolic perturbations that may be present. New hypotheses obtained from the study will assist in metabolic engineering efforts of improved strains exhibiting higher fatty acid yields and productivities.
Project description:Persisters represent a small bacterial population that is dormant and that survives under antibiotic treatment without experiencing genetic adaptation. Persisters are also considered one of the major reasons for recalcitrant chronic bacterial infections. Although several mechanisms of persister formation have been proposed, it is not clear how cells enter the dormant state in the presence of antibiotics or how persister cell formation can be effectively controlled. A fatty acid compound, cis-2-decenoic acid, was reported to decrease persister formation as well as revert the dormant cells to a metabolically active state. We reasoned that some fatty acid compounds may be effective in controlling bacterial persistence because they are known to benefit host immune systems. This study investigated persister cell formation by pathogens that were exposed to nine fatty acid compounds during antibiotic treatment. We found that three medium chain unsaturated fatty acid ethyl esters (ethyl trans-2-decenoate, ethyl trans-2-octenoate, and ethyl cis-4-decenoate) decreased the level of Escherichia coli persister formation up to 110-fold when cells were exposed to ciprofloxacin or ampicillin antibiotics. RNA sequencing analysis and gene deletion persister studies elucidated that these fatty acids inhibit bacterial persistence by regulating antitoxin HipB. A similar persister cell reduction was observed for pathogenic E. coli EDL933, Pseudomonas aeruginosa PAO1, and Serratia marcescens ICU2-4 strains. This study demonstrates that fatty acid ethyl esters can be used to disrupt bacterial dormancy to combat persistent infectious diseases.
Project description:Comparative analysis of changes in gene and protein expression and fatty acid profiles between Escherichia coli K-12 MG1655 ΔfadD ΔaraBAD expressing an acyl-acyl carrier protein thioesterase from Umbellularia californica (BTE) or a non-functional mutant thioesterase (BTE-H204A) to determine the functional basis for losses in cell viability, membrane integrity, or other stresses and metabolic perturbations that may be present. New hypotheses obtained from the study will assist in metabolic engineering efforts of improved strains exhibiting higher fatty acid yields and productivities. Cultures of fatty acid overproducing (BTE-expressing) and negative control (non-functional BTE-H204A-expressing) strains of Escherichia coli K-12 MG1655 delta-fadD delta-araBAD (deficient in beta-oxidation and L-arabinose catabolism) were sampled under two different sets of media/induction/antibiotic conditions. These conditions were shake flasks at 37C, 250 rpm shaking, in EZ rich defined medium supplemented with 0.2% glucose and 0.01 mM biotin (EZglu), and in fermentors at 37C with controlled air sparging, agitation, and pH in EZ rich defined medium supplemented with 0.4% glycerol and 0.01 mM biotin (EZgly). Two strains were analyzed in the EZglu experiment, the background strain harboring either pTrc99A-BTE (fatty acid overproducing) or pTrc99A-BTE-H204A (control phenotype). Three strains were analyzed in the EZgly experiment, with the background strain haboring either pBAD35-BTE and pBAD33 (fatty acid overproducing), pBAD35-BTE and pBAD33-ACC (fatty acid overproducing, ACC are the 4 subunits of E. coli K-12 acetyl-CoA carboxylase expressed as an artificial operon accDABC in plasmid pBAD33), and pBAD35-BTE-H204A and pBAD33 (control phenotype). RNA was extracted from harvested cell pellets from biological triplicates (EZglu) or biological duplicates (EZgly) of each strain at three different sampling times as defined in each sample description. Due to a hybridization or scanning problem, biological duplicates rather than triplicates were analyzed at the mid-stationary phase sampling point in the EZglu experiment for the control strain harboring pTrc99A-BTE-H204A. Multiple technical replicates at either the hybridization or sample level were analyzed from the biological duplicates of the fermentor experiment. The form of technical replicate (sample or hybridization) is specified in each EZgly sample description.
Project description:transcriptome analysis of enterohemorrhagic E. coli treated with either one of two different concentrations of short chain fatty acid mixes or the corresponding sodium chloride osmolarity control