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Development of a fixative protocol using formaldehyde and gluteraldehyde for preservation of microbial art on agar plates.

Wilson, Sammi; Law, Samantha P.; McEwan, Neil R.; Wright, Rebecca; Macaskill, Jenny S.


Sammi Wilson

Samantha P. Law

Neil R. McEwan

Rebecca Wright

Jenny S. Macaskill


Aims: Agar art bridges the gap between science and art using microbes instead of paint. Afterwards, the art can change in response to microbial fluctuation, meaning preservation of the original art is essential. Here, formaldehyde and glutaraldehyde were investigated as preservatives, involving techniques used in healthcare settings to preserve samples. Methods and Results: Formaldehyde was tested at 1.0%, 2.0% and 3.7%, w/v, whereas glutaraldehyde was tested at 1% and 2.5%, w/v. Both compounds and respective concentrations were tested for different time periods. Escherichia coli, Serratia marcescens, Staphlococcus aureus and Micrococcus luteus were used as bacteria for “drawing” the works of art. The effectiveness of fixation was determined using integrated densities and visual assessment. Initially, both compounds showed potential promise, albeit with a loss of bacteria. Ser. marcescens was prone to colour changes and glutaraldehyde caused discolouration of agar and bacteria. These could be caused by a pH decrease in the agar, due to residual free aldehyde groups. Reduction of this was tested using 300 mM sodium metabisulfite to neutralize excess aldehydes. This initially led to reduced bacterial loss and avoided colour changes, however measurements 24 h post-fixation showed colour loss to some bacterial clusters. Conclusions: Here, at least 2% formaldehyde for a short fixation period, typically 1min, depending on the species, was most promising for the preservation of art. Given the success of this with different bacteria, it would make a good starting combination for anyone trying to fix agar art, although methodology refinement may be needed for optimisation depending on the bacterial species used. Significance and Impact of Study: This study shows, for the first time, successful fixation and preservation of different bacterial species on agar. The impact of this is to preserve agar art while making it safe and non-infective to those in contact with the microbial art.


WILSON, S., LAW, S.P., MCEWAN, N.R., WRIGHT, R. and MACASKILL, J.S. [2022]. Development of a fixative protocol using formaldehyde and gluteraldehyde for preservation of microbial art on agar plates. Journal of applied microbiology [online], 133(2), pages 665-672. Available from:

Journal Article Type Article
Acceptance Date Apr 20, 2022
Online Publication Date Apr 27, 2022
Publication Date Aug 31, 2022
Deposit Date May 10, 2022
Publicly Available Date May 10, 2022
Journal Journal of applied microbiology
Print ISSN 1364-5072
Electronic ISSN 1365-2672
Publisher Wiley
Peer Reviewed Peer Reviewed
Volume 133
Issue 2
Pages 665-672
Keywords Fixation (Histology); Agar plates; Agar art; Bacterial art; Science and art
Public URL


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