Risk assessment and bioburden evaluation of Agrobacterium tumefaciens-mediated transient protein expression in plants using the CaMV35S promoter

Springer Science and Business Media LLC - Tập 23 - Trang 1-12 - 2023
Matthias Knödler1,2, Paul Winman Reunious1,2, Johannes Felix Buyel1,2,3
1Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Aachen, Germany
2Institute for Molecular Biotechnology, RWTH Aachen University, Aachen, Germany
3Department of Biotechnology (DBT), Institute of Bioprocess Science and Engineering (IBSE), University of Natural Resources and Life Sciences, Vienna (BOKU), Vienna, Austria

Tóm tắt

Large-scale transient expression of recombinant proteins in plants is increasingly used and requires the multi-liter cultivation of Agrobacterium tumefaciens transformed with an expression vector, which is often cloned in Escherichia coli first. Depending on the promoter, unintentional activity can occur in both bacteria, which could pose a safety risk to the environment and operators if the protein is toxic. To assess the risk associated with transient expression, we first tested expression vectors containing the CaMV35S promoter known to be active in plants and bacteria, along with controls to measure the accumulation of the corresponding recombinant proteins. We found that, in both bacteria, even the stable model protein DsRed accumulated at levels near the detection limit of the sandwich ELISA (3.8 µg L−1). Higher levels were detected in short cultivations (< 12 h) but never exceeded 10 µg L−1. We determined the abundance of A. tumefaciens throughout the process, including infiltration. We detected few bacteria in the clarified extract and found none after blanching. Finally, we combined protein accumulation and bacterial abundance data with the known effects of toxic proteins to estimate critical exposures for operators. We found that unintended toxin production in bacteria is negligible. Furthermore, the intravenous uptake of multiple milliliters of fermentation broth or infiltration suspension would be required to reach acute toxicity even when handling the most toxic products (LD50 ~ 1 ng kg−1). The unintentional uptake of such quantities is unlikely and we therefore regard transient expression as safe in terms of the bacterial handling procedure.

Tài liệu tham khảo

Hundleby PAC, Sack M, Twyman RM. Biosafety, risk assessment, and regulation of molecular farming. Mol Pharm. 2018. https://doi.org/10.1002/9781118801512.ch13.

Potts PJMJ. Centers for Disease Control and Prevention National Institutes of Health: Biosafety in Microbiological and Biomedical Laboratories. U.S. Department of Health and Human Services, Revised June 2020. 6th Edition.

Richmond JY. The 1, 2, 3's of biosafety levels. Office of Health and Safety: Centers for Disease Control and Prevention. https://www.aphl.org/programs/preparedness/Smallpox/pdf/the-1-2-3s-of-biosafety-levels.pdf. Accessed 8 Apr 2022.

Salerno RM, Gaudioso J. Laboratory biorisk management: biosafety and biosecurity. UK: CRC Press; 2015.

Benfey PN, Chua NH. The cauliflower mosaic virus 35S promoter: combinatorial regulation of transcription in plants. Science. 1990;250(4983):959–66.

Lewin A, et al. Gene expression in bacteria directed by plant-specific regulatory sequences. Transgenic Res. 2004;7:403–11.

Bennett A, et al. Laboratory biosafety manual fourth edition and associated monographs laboratory design and maintainance. 2020: World Health Organization.

Partiament E. DIRECTIVE 2000/54/EC OF THE EUROPEAN PARLIAMENT AND OF THE COUNCIL. Official Journal of the European Communities, 2000: p. L 262/21.

DiBerardinis LJ, et al. Guidelines for laboratory design: health, safety, and environmental considerations. In: Guidelines for laboratory design: health, safety, and environmental considerations. Wiley; 2013. p. 196–215.

Bundesministerium für Ernährung, L.u.V., Bekanntmachung der Liste risikobewerteter Spender-und Empfängerorganismen für gentechnische Arbeiten. 2013.

Tabor, S., Expression using the T7 RNA polymerase/promoter system. Current Protocols in Molecular Biology, 2001. Chapter 16: p. Unit16.2.

Limpert E, Stahel WA, Abbt M. Log-normal Distributions across the Sciences: Keys and Clues: On the charms of statistics, and how mechanical models resembling gambling machines offer a link to a handy way to characterize log-normal distributions, which can provide deeper insight into variability and probability—normal or log-normal: that is the question. Bioscience. 2001;51(5):341–52.

Buyel JF, et al. The impact of Pseudomonas syringae type III effectors on transient protein expression in tobacco. Plant Biol. 2015;17(2):484–92.

Morton ER, Fuqua C. Laboratory maintenance of Agrobacterium. Current protocols in microbiology, 2012. Chapter 1: p. Unit3D.1.

Trivedi RN, et al. High-level production of plasmid DNA by Escherichia coli DH5α ΩsacB by introducing inc mutations. Appl Environ Microbiol. 2014;80(23):7154–60.