Project description:Streptomyces albus S12, TK and Tet30Chl25 are the parental strain , low-yield and high-yield of salinomycin mutant obtained by ARTP and ribosome engineering ,respectively. There are total 1602 differentially expressed genes (DEGs) show differences in expression between the mutant strain TK, Tet30Chl25 and the initial strain S12. KEGG pathway analysis of differentially expressed genes (DEGs) between the mutant strain TK, Tet30Chl25 and the initial strain S12 show that the relevant differential pathways affecting salinomycin production were mainly related to butanoate metabolism, starch and sucrose metabolism, glyoxylate metabolism. Besides , the transcription of genes in the salinomycin biosynthesis gene cluster and the transcription level of related genes in the precursors biosynthesis pathway were more active in the high-yield salinomycin production strain Tet30Chl25. Furthermore, the transcription level ribosomal protein, string response, two component system and sigma factors are more active in high-yield of salinomycin mutants and that may involve in regulation of salinomycin biosynthesis and may account for the high-yield of salinomycin.
Project description:Pseudomonas putida S12 is an inherently solvent-tolerant strain and constitutes a promising platform for biotechnology applications in whole-cell biocatalysis of aromatic compounds. The genome of P. putida S12 consists of a 5.8 Mbp chromosome and a 580 kbp megaplasmid pTTS12. pTTS12 encodes several genes which enable the tolerance to various stress conditions, including the main solvent efflux pump SrpABC. Removal (curing) of megaplasmid pTTS12 and subsequent loss of solvent efflux pump SrpABC caused a significant reduction in solvent tolerance of the resulting strain. In this study, we succeeded in restoring solvent tolerance in the megaplasmid-cured P. putida S12 using adaptive laboratory evolution (ALE) and molecular analysis to investigate the intrinsic solvent tolerance of P. putida S12. RNA-seq was performed to study the global transcriptomic response of the solvent-adapted plasmid-cured P. putida S12 in the presence of toluene. This analysis revealed the downregulation of ATP synthase, flagella and other RND efflux pumps, which indicates the importance of maintaining proton motive force during solvent stress.
Project description:Several microorganisms have wide temperature growth range and versatility to tolerate large thermal fluctuations in diverse environments. To better understand thermal adaptation of psychrotrophs, Exiguobacterium sibiricum strain 255-15 was used, a psychrotrophic bacterium that grows from -5°C to 39°C. Its genome is approximately 3 Mb in size, has a GC content of 47.7% and includes 2,978 putative protein-encoding genes (CDS). The genome and transcriptome analysis along with the organism's known physiology was used to better understand its thermal adaptation. A total of about 27%, 3.2% and 5.2% of E. sibiricum strain 255-15 CDS spotted on the DNA microarray yielded differentially expressed genes in cells grown at -2.5°C, 10°C and 39°C, respectively, when compared to cells grown at 28°C. The hypothetical and unknown genes represented 10.6%, 0.89% and 2.3% of the CDS differentially expressed when grown at -2.5°C, 10°C and 39°C versus 28°C. The transcriptome analyses showed that E. sibiricum is constitutively adapted to cold temperatures since little differential gene expression was observed at growth temperatures of 10°C and 28°C, but at the extremities of its Arrhenius growth profile, namely -2.5°C and 39°C, much more differential gene expression occurred. The genes that responded were more typically associated with stress response. Keywords: stress response to cold and hot temperatures