Project description:Limited functional annotation of the Z. mobilis genome is a current barrier to both basic studies of Z. mobilis and its development as a synthetic-biology chassis. To gain insight, we collected sample-matched multiomics data including RNA-seq, transcription start site sequencing (TSS-seq), termination sequencing (term-seq), ribosome profiling, and label-free shotgun proteomic mass spectrometry across different growth conditions to improve annotation and assign functional sites in the Z. mobilis genome. Proteomics and ribosome profiling informed revisions of protein-coding genes, which included 44 start codon changes and 42 added proteins.
Project description:Investigation of whole-genome gene expression level changes in RDM-4 strain of Zymomonas mobilis respiration-deficient mutant compared to the wild-type strain. The mutant strains were isolated from the antibiotics-resistant mutants of Z. mobilis ZM6. The RDM strains exhibited much higher ethanol fermentation abilities than the wild-type strain under aerobic conditions. The strains also gained thermotolerance and exhibited higher ethanol productivities at high temperature (39 ºC) under both non-aerobic and aerobic conditions compared with the wild-type strain. To evaluate the mechanisms of aerobic fermentation and thermotolerance of the RDM strain, we performed the microarray experiments.
Project description:Investigation of whole-genome gene expression level changes in RDM-4 strain of Zymomonas mobilis respiration-deficient mutant compared to the wild-type strain. The mutant strains were isolated from the antibiotics-resistant mutants of Z. mobilis ZM6. The RDM strains exhibited much higher ethanol fermentation abilities than the wild-type strain under aerobic conditions. The strains also gained thermotolerance and exhibited higher ethanol productivities at high temperature (39 ºC) under both non-aerobic and aerobic conditions compared with the wild-type strain. To evaluate the mechanisms of aerobic fermentation and thermotolerance of the RDM strain, we performed the microarray experiments. A four-chip study using total RNA recovered from the shaking cultures of wt and RDM-4 strains grown at 30ºC, a non-aerobic culture of wt strain grown at 30ºC, and a non-aerobic culture of RDM-4 strain grown at 38ºC. Each chip measures the expression level of 1,998 genes from Z. mobilis.
Project description:We report the genome changes associated with a Zymomonas mobilis sodium acetate-tolerant mutant (AcR). We used comparative genomics, transcriptomics, and genetics to show nhaA over-expression conferred sodium acetate (NaAc) tolerance in Z. mobilis. We observed a synergistic effect for sodium and acetate ions that enhanced toxicity against the wild-type strain (ZM4), which was not observed for similar concentrations of potassium and ammonium acetate under controlled laboratory conditions. We extended our studies and demonstrated that Saccharomyces cerevisiae sodium-proton antiporter genes contribute to NaAc tolerance for this important ethanologen. The application of classical and systems biology tools is a paradigm for industrial strain improvement and combines benefits of few a priori assumptions with detailed, rapid, mechanistic studies. Finally, our studies reinforce the idea that one obtains what one selects for in mutant screens and that a genetic system is important for industrial strain development. ZM4_ACr_NaCl_NaAc_study. Whole-genome expression profiles of exponential and stationary phase cells were analyzed for the wild-type Zymomonas mobilis ZM4 and the acetate-tolerant mutant AcR under 12g/L sodium acetate and same molar concentration of sodium chloride (8.55g/L) control conditions.
