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Dynamic cell responses in Thermoanaerobacterium sp. under hyperosmotic stress.

ABSTRACT: As a nongenetic engineering technique, adaptive evolution is an effective and easy-to-operate approach to strain improvement. In this work, a commercial Thermoanaerobacterium aotearoense SCUT27/?ldh-G58 was successfully isolated via sequential batch fermentation with step-increased carbon concentrations. Mutants were isolated under selective high osmotic pressures for 58 passages. The evolved isolate rapidly catabolized sugars at high concentrations and subsequently produced ethanol with good yield. A 1.6-fold improvement of ethanol production was achieved in a medium containing 120?g/L of carbon substrate using the evolved strain, compared to the start strain. The analysis of transcriptome and intracellular solute pools suggested that the adaptive evolution altered the synthesis of some compatible solutes and activated the DNA repair system in the two Thermoanaerobacterium sp. evolved strains. Overall, the results indicated the potential of adaptive evolution as a simple and effective tool for the modification and optimization of industrial microorganisms.

SUBMITTER: Zhu M

PROVIDER: S-EPMC5577258 | biostudies-literature | 2017 Aug

REPOSITORIES: biostudies-literature

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Dynamic cell responses in Thermoanaerobacterium sp. under hyperosmotic stress.

Zhu Muzi M Fan Wudi W Cha Yaping Y Yang Xiaofeng X Lai Zhicheng Z Li Shuang S Wang Xiaoning X

Scientific reports 20170830 1

As a nongenetic engineering technique, adaptive evolution is an effective and easy-to-operate approach to strain improvement. In this work, a commercial Thermoanaerobacterium aotearoense SCUT27/Δldh-G58 was successfully isolated via sequential batch fermentation with step-increased carbon concentrations. Mutants were isolated under selective high osmotic pressures for 58 passages. The evolved isolate rapidly catabolized sugars at high concentrations and subsequently produced ethanol with good yi ...[more]

PMID: 28855699

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Project description:The Atlantic killifish (Fundulus heteroclitus), native to estuarine areas of the Atlantic coast of the United States, has become a valuable ecotoxicological model as a result of its ability to acclimate to rapid environmental changes and adapt to polluted habitats. MicroRNAs (miRNAs) are highly conserved small RNAs that regulate gene expression and play critical roles in stress responses in a variety of organisms. Global miRNA expression in killifish and the potential roles miRNA have in environmental acclimation have yet to be characterized. Accordingly, we profiled miRNA expression in killifish gill for the first time and identified a small group of highly expressed, well-conserved miRNAs as well as 16 novel miRNAs not yet identified in other organisms. Killifish respond to large fluctuations in salinity with rapid changes in gene expression and protein trafficking to maintain osmotic balance, followed by a secondary phase of gene and protein expression changes that enable remodeling of the gills. Arsenic, a major environmental toxicant, was previously shown to inhibit gene expression responses in killifish gill, as well the ability of killifish to acclimate to a rapid increase in salinity. Thus, we examined the individual and combined effects of salinity and arsenic on miRNA expression in killifish gill. Using small RNA sequencing, we identified 270 miRNAs expressed in killifish, and found that miR-135b was differentially expressed in response to arsenic and at 24?h following transfer to salt water. Predicted targets of miR-135b are involved in ion transport, cell motility and migration, GTPase mediated signal transduction and organelle assembly. Consistent with previous studies of these two environmental stressors, we found a significant interaction (i.e., arsenic dependent salinity effect), whereby killifish exposed to arsenic exhibited an opposite response in miR-135b expression at 24?h post hyperosmotic challenge compared to controls. By examining mRNA expression of predicted miRNA targets during salinity acclimation and arsenic exposure, we found that miR-135b targets were significantly more likely to decrease during salinity acclimation than non-targets. Our identification of a significant interaction effect of arsenic and salinity on miR-135b expression supports the hypothesis that arsenic alters upstream regulators of stress response networks, which may adversely affect the killifish response to osmotic stress. The characterization of miRNAs in this ecotoxicological model will be a valuable resource for future studies investigating the role of miRNAs in response to environmental stress.

Dataset Information

Dynamic cell responses in Thermoanaerobacterium sp. under hyperosmotic stress.

Publications

Dynamic cell responses in Thermoanaerobacterium sp. under hyperosmotic stress.

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