Environmental regulation of PndbA600, an auto-inducible promoter for two-stage industrial biotechnology in cyanobacteria

Madsen, M. A., Hamilton, G., Herzyk, P. and Amtmann, A. (2021) Environmental regulation of PndbA600, an auto-inducible promoter for two-stage industrial biotechnology in cyanobacteria. Frontiers in Bioengineering and Biotechnology, 8, 619055. (doi: 10.3389/fbioe.2020.619055)

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Cyanobacteria are photosynthetic prokaryotes being developed as sustainable platforms that use renewable inputs (light, water and air) for diverse applications in energy, food, environment and medicine. Despite the attractive promise cyanobacteria offer industrial biotechnology, slow growth rates pose a major challenge in processes which typically require large amounts of biomass and are often toxic to the cells. Two-stage cultivation strategies are an attractive solution to prevent any undesired growth inhibition by de-coupling biomass accumulation (stage I) and the industrial process (stage II). In cyanobacteria, two-stage strategies involve costly transfer methods between stages I and II and little work has focused on using the distinct growth and stationary phases of batch cultures to auto-regulate stage transition. In this work, we identified and characterised a growth phase-specific promoter, which can serve as an auto-inducible switch to regulate two-stage bioprocesses in cyanobacteria. First, growth phase-specific genes were identified from a new RNAseq dataset comparing two growth phases and six nutrient conditions in Synechocystis sp. PCC 6803 including two new transcriptomes for low Mg and low K. A type II NADH dehydrogenase (ndbA) showed robust induction when the cultures transitioned from exponential to stationary growth. Behaviour of a 600-bp promoter sequence (PndbA) was then characterised in detail following expression of PndbA:GFP in Synechococcus sp. PCC 7002. Culture density and growth media analyses showed that PndbA activation was not dependent on increases in culture density per se, but on N availability and another activating factor present in the spent media of stationary phase cultures (Factor X). PndbA deactivation was dependent on changes in culture density and either N availability or Factor X. Electron transport inhibition studies revealed a photosynthesis-specific enhancement of active PndbA levels. Our findings are summarised in a model describing the environmental regulation of PndbA which can now inform the rational design of two-stage industrial processes in cyanobacteria.

Item Type:Articles
Glasgow Author(s) Enlighten ID:Hamilton, Dr Graham and Madsen, Miss Mary Ann and Amtmann, Professor Anna and Herzyk, Dr Pawel
Authors: Madsen, M. A., Hamilton, G., Herzyk, P., and Amtmann, A.
College/School:College of Medical Veterinary and Life Sciences
College of Medical Veterinary and Life Sciences > Institute of Molecular Cell and Systems Biology
Journal Name:Frontiers in Bioengineering and Biotechnology
Publisher:Frontiers Media
ISSN (Online):2296-4185
Copyright Holders:Copyright © 2021 Madsen, Hamilton, Herzyk and Amtmann
First Published:First published in Frontiers in Bioengineering and Biotechnology 8:619055
Publisher Policy:Reproduced under a Creative Commons licence

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Project CodeAward NoProject NamePrincipal InvestigatorFunder's NameFunder RefLead Dept
190359Biodesalination: from cell to tap.Anna AmtmannEngineering and Physical Sciences Research Council (EPSRC)EP/J004871/1MCSB - Plant Sciences
302195Combining chemical priming and quantitative genetics to increase salt tolerance of soybeanAnna AmtmannBiotechnology and Biological Sciences Research Council (BBSRC)BB/R019894/1Institute of Molecular, Cell & Systems Biology
172121Funding SchemesAnna DominiczakWellcome Trust (WELLCOTR)105614/Z/14/ZInstitute of Cardiovascular & Medical Sciences