Skip to main content

Research Repository

Advanced Search

Effect of natural antibacterial clays against single biofilm formation by Staphylococcus aureus and Salmonella Typhimurium bacteria on a stainless-steel surface

Wan Omar, Wan Hasyera; Mahyudin, Nor Ainy; Azmi, Nur Naqiyah; Mahmud Ab Rashid, Nor-Khaizura; Ismail, Roslan; Mohd Yusoff, Mohd Hafis Yuswan; Khairil Mokhtar, Nur Fadhilah; Sharples, Gary J.


Wan Hasyera Wan Omar

Nor Ainy Mahyudin

Nur Naqiyah Azmi

Nor-Khaizura Mahmud Ab Rashid

Roslan Ismail

Mohd Hafis Yuswan Mohd Yusoff

Nur Fadhilah Khairil Mokhtar


Staphylococcus aureus and Salmonella Typhimurium have a propensity to develop biofilms on food contact surfaces, such as stainless-steel, that persist despite rigorous cleaning and sanitizing procedures. Since both bacterial species pose a significant public health risk within the food chain, improved anti-biofilm measures are needed. This study examined the potential of clays as antibacterial and anti-biofilm agents against these two pathogens on appropriate contact surfaces. Natural soil was processed to yield leachates and suspensions of both untreated and treated clays. Soil particle size, pH, cation-exchange capacity, and metal ions were characterized to assess their importance in bacterial killing. Initial antibacterial screening was performed on nine distinct types of natural Malaysian soil using a disk diffusion assay. Untreated leachate from Kuala Gula and Kuala Kangsar clays were found to inhibit S. aureus (7.75 ± 0.25 mm) and Salmonella Typhimurium (11.85 ± 1.63 mm), respectively. The treated Kuala Gula suspension (50.0 and 25.0 %) reduced S. aureus biofilms by 4.4 and 4.2 log at 24 and 6 h, respectively, while treated Kuala Kangsar suspension (12.5 %) by a 4.16 log reduction at 6 h. Although less effective, the treated Kuala Gula leachate (50.0 %) was effective in removing Salmonella Typhimurium biofilm with a decrease of >3 log in 24 h. In contrast to Kuala Kangsar clays, the treated Kuala Gula clays contained a much higher soluble metal content, especially Al (301.05 ± 0.45 ppm), Fe (691.83 ± 4.80 ppm) and Mg (88.44 ± 0.47 ppm). Elimination of S. aureus biofilms correlated with the presence of Fe, Cu, Pb, Ni, Mn and Zn irrespective of the pH of the leachate. Our findings demonstrate that a treated suspension is the most effective for eradication of S. aureus biofilms with a potential as a sanitizer-tolerant, natural antibacterial against biofilms for applications in the food industry.


Wan Omar, W. H., Mahyudin, N. A., Azmi, N. N., Mahmud Ab Rashid, N., Ismail, R., Mohd Yusoff, M. H. Y., …Sharples, G. J. (2023). Effect of natural antibacterial clays against single biofilm formation by Staphylococcus aureus and Salmonella Typhimurium bacteria on a stainless-steel surface. International Journal of Food Microbiology, 394, Article 110184.

Journal Article Type Article
Acceptance Date Mar 15, 2023
Online Publication Date Mar 28, 2023
Publication Date Jun 2, 2023
Deposit Date Jan 18, 2024
Journal International Journal of Food Microbiology
Print ISSN 0168-1605
Publisher Elsevier
Peer Reviewed Peer Reviewed
Volume 394
Article Number 110184
Keywords General Medicine; Microbiology; Food Science
Public URL