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Lookup NU author(s): Leah Ada Constantinou Constantinou, Robin Kaur, Dr Gary Caldwell
This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).
© 2026 by the authors.Zeolites are naturally abundant, low-cost aluminosilicate minerals commonly found in sedimentary rock. The surface chemistry of zeolite can be modified via cationic surfactant loading, termed a surfactant-modified zeolite (SMZ), that can be used as an antimicrobial technology in water treatment processes. This raises the possibility that SMZs could be utilised to treat blooms of harmful algae and cyanobacteria; however, there is a lack of understanding of the toxicity of SMZs to non-target microorganisms, including non-problematic algae and cyanobacteria. To address this knowledge gap, this research investigates whether hexadecyltrimethylammonium-bromide (HDTMA-Br) SMZs are toxic to the cyanobacterium Synechococcus elongatus and the microalgae Chlorella vulgaris, Nannochloropsis oculata and Duniallela salina. The cells were exposed to natural zeolite, HDTMA-Br surfactant and HDTMA-Br SMZ for 24 h and analysed 2- and 26 h post-exposure via flow cytometry and imaging pulse amplitude modulated fluorometry. There was an overall trend of reduced cell density in the SMZ and surfactant treatments. The SMZ treatment reduced the effective PSII quantum yield (Y(II)) but increased the quantum yield of regulated energy dissipation for C. vulgaris. When exposed to the surfactant treatment, no Y(II) signals were detected from any species. We conclude that SMZs are toxic to non-target microorganisms, with resilience dependent upon cell wall structure.
Author(s): Constantinou LA, Kaur RN, Caldwell GS
Publication type: Article
Publication status: Published
Journal: Applied Sciences
Year: 2026
Volume: 16
Issue: 10
Online publication date: 11/05/2026
Acceptance date: 06/05/2026
Date deposited: 08/06/2026
ISSN (electronic): 2076-3417
Publisher: Multidisciplinary Digital Publishing Institute (MDPI)
URL: https://doi.org/10.3390/app16104741
DOI: 10.3390/app16104741
Data Access Statement: The raw data supporting the conclusions of this article will be made available by the authors on request
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