Broad-Spectrum Antimicrobial and Antibiofilm Activity of a Natural Clay Mineral from British Columbia, Canada

ABSTRACT Worldwide increases in antibiotic resistance and the dearth of new antibiotics have created a global crisis in the treatment of infectious diseases. These concerns highlight the pressing need for novel antimicrobial agents. Natural clay minerals have a long history of therapeutic and biomed...

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Autores principales:	Shekooh Behroozian, Sarah L. Svensson, Loretta Y. Li, Julian E. Davies
Formato:	article
Lenguaje:	EN
Publicado:	American Society for Microbiology 2020
Materias:	antibacterial agent clay mineral antimicrobial clay bacterial biofilm fungal pathogen Microbiology QR1-502
Acceso en línea:	https://doaj.org/article/2c6f4652c70244d4adbd067758a8d91a
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spelling	oai:doaj.org-article:2c6f4652c70244d4adbd067758a8d91a2021-11-15T16:19:07ZBroad-Spectrum Antimicrobial and Antibiofilm Activity of a Natural Clay Mineral from British Columbia, Canada10.1128/mBio.02350-202150-7511https://doaj.org/article/2c6f4652c70244d4adbd067758a8d91a2020-10-01T00:00:00Zhttps://journals.asm.org/doi/10.1128/mBio.02350-20https://doaj.org/toc/2150-7511ABSTRACT Worldwide increases in antibiotic resistance and the dearth of new antibiotics have created a global crisis in the treatment of infectious diseases. These concerns highlight the pressing need for novel antimicrobial agents. Natural clay minerals have a long history of therapeutic and biomedical applications and have lately received specific attention for their potent antimicrobial properties. In particular, Kisameet clay (KC) has strong antibacterial activity against a variety of multidrug-resistant (MDR) bacterial pathogens in vitro. Here, we have extended the known spectrum of activity of KC by demonstrating its efficacy against two major fungal pathogens, Candida albicans and Cryptococcus neoformans. In addition, KC also exhibits potent activity against the opportunistic bacterial pathogen Mycobacterium marinum, a model organism for M. ulcerans infection. Moreover, aqueous KC leachates (KC-L) exhibited broad-spectrum antibacterial activity, eradicated Gram-negative and Gram-positive biofilms, and prevented their formation. The mechanism(s) underlying KC antibacterial activity appears to be complex. Adjusting KC-L to neutral pH rendered it inactive, indicating a contribution of pH, although low pH alone was insufficient for its antibacterial activity. Treatment of KC minerals with cation-chelating agents such as EDTA, 2,2′-bipyridyl, and deferoxamine reduced the antibacterial activity, while supplementation of KC-L with these chelating agents eliminated the inhibitory activity. Together, the data suggest a positive role for divalent and trivalent cations, including iron and aluminum, in bacterial inhibition by KC. Collectively, these studies demonstrate the range of KC bioactivity and provide a better understanding of the mechanism underlying its antibacterial effects. IMPORTANCE The escalating emergence of multidrug-resistant (MDR) bacteria, together with the paucity of novel antimicrobial agents in antibiotic development, is recognized as a worldwide public health crisis. Kisameet clay (KC), found in British Columbia (BC), Canada, is a clay mineral with a long history of therapeutic applications among people of the First Nations. We previously reported the antibacterial activity of KC against a group of MDR clinical pathogens. Here, we demonstrate its activity against two major human-pathogenic fungal species, as well as against bacterial biofilms, which underlie many recalcitrant bacterial infections. In these studies, we also identified several geochemical characteristics of KC, such as metal ions and low pH, which are involved in its antibacterial activity. These findings provide a better understanding of the components of KC antibacterial activity and a basis for developing defined preparations of this clay mineral for therapeutic applications.Shekooh BehroozianSarah L. SvenssonLoretta Y. LiJulian E. DaviesAmerican Society for Microbiologyarticleantibacterial agentclay mineralantimicrobial claybacterial biofilmfungal pathogenMicrobiologyQR1-502ENmBio, Vol 11, Iss 5 (2020)
institution	DOAJ
collection	DOAJ
language	EN
topic	antibacterial agent clay mineral antimicrobial clay bacterial biofilm fungal pathogen Microbiology QR1-502
spellingShingle	antibacterial agent clay mineral antimicrobial clay bacterial biofilm fungal pathogen Microbiology QR1-502 Shekooh Behroozian Sarah L. Svensson Loretta Y. Li Julian E. Davies Broad-Spectrum Antimicrobial and Antibiofilm Activity of a Natural Clay Mineral from British Columbia, Canada
description	ABSTRACT Worldwide increases in antibiotic resistance and the dearth of new antibiotics have created a global crisis in the treatment of infectious diseases. These concerns highlight the pressing need for novel antimicrobial agents. Natural clay minerals have a long history of therapeutic and biomedical applications and have lately received specific attention for their potent antimicrobial properties. In particular, Kisameet clay (KC) has strong antibacterial activity against a variety of multidrug-resistant (MDR) bacterial pathogens in vitro. Here, we have extended the known spectrum of activity of KC by demonstrating its efficacy against two major fungal pathogens, Candida albicans and Cryptococcus neoformans. In addition, KC also exhibits potent activity against the opportunistic bacterial pathogen Mycobacterium marinum, a model organism for M. ulcerans infection. Moreover, aqueous KC leachates (KC-L) exhibited broad-spectrum antibacterial activity, eradicated Gram-negative and Gram-positive biofilms, and prevented their formation. The mechanism(s) underlying KC antibacterial activity appears to be complex. Adjusting KC-L to neutral pH rendered it inactive, indicating a contribution of pH, although low pH alone was insufficient for its antibacterial activity. Treatment of KC minerals with cation-chelating agents such as EDTA, 2,2′-bipyridyl, and deferoxamine reduced the antibacterial activity, while supplementation of KC-L with these chelating agents eliminated the inhibitory activity. Together, the data suggest a positive role for divalent and trivalent cations, including iron and aluminum, in bacterial inhibition by KC. Collectively, these studies demonstrate the range of KC bioactivity and provide a better understanding of the mechanism underlying its antibacterial effects. IMPORTANCE The escalating emergence of multidrug-resistant (MDR) bacteria, together with the paucity of novel antimicrobial agents in antibiotic development, is recognized as a worldwide public health crisis. Kisameet clay (KC), found in British Columbia (BC), Canada, is a clay mineral with a long history of therapeutic applications among people of the First Nations. We previously reported the antibacterial activity of KC against a group of MDR clinical pathogens. Here, we demonstrate its activity against two major human-pathogenic fungal species, as well as against bacterial biofilms, which underlie many recalcitrant bacterial infections. In these studies, we also identified several geochemical characteristics of KC, such as metal ions and low pH, which are involved in its antibacterial activity. These findings provide a better understanding of the components of KC antibacterial activity and a basis for developing defined preparations of this clay mineral for therapeutic applications.
format	article
author	Shekooh Behroozian Sarah L. Svensson Loretta Y. Li Julian E. Davies
author_facet	Shekooh Behroozian Sarah L. Svensson Loretta Y. Li Julian E. Davies
author_sort	Shekooh Behroozian
title	Broad-Spectrum Antimicrobial and Antibiofilm Activity of a Natural Clay Mineral from British Columbia, Canada
title_short	Broad-Spectrum Antimicrobial and Antibiofilm Activity of a Natural Clay Mineral from British Columbia, Canada
title_full	Broad-Spectrum Antimicrobial and Antibiofilm Activity of a Natural Clay Mineral from British Columbia, Canada
title_fullStr	Broad-Spectrum Antimicrobial and Antibiofilm Activity of a Natural Clay Mineral from British Columbia, Canada
title_full_unstemmed	Broad-Spectrum Antimicrobial and Antibiofilm Activity of a Natural Clay Mineral from British Columbia, Canada
title_sort	broad-spectrum antimicrobial and antibiofilm activity of a natural clay mineral from british columbia, canada
publisher	American Society for Microbiology
publishDate	2020
url	https://doaj.org/article/2c6f4652c70244d4adbd067758a8d91a
work_keys_str_mv	AT shekoohbehroozian broadspectrumantimicrobialandantibiofilmactivityofanaturalclaymineralfrombritishcolumbiacanada AT sarahlsvensson broadspectrumantimicrobialandantibiofilmactivityofanaturalclaymineralfrombritishcolumbiacanada AT lorettayli broadspectrumantimicrobialandantibiofilmactivityofanaturalclaymineralfrombritishcolumbiacanada AT julianedavies broadspectrumantimicrobialandantibiofilmactivityofanaturalclaymineralfrombritishcolumbiacanada
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Broad-Spectrum Antimicrobial and Antibiofilm Activity of a Natural Clay Mineral from British Columbia, Canada

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