title: Dirty Money: A Matter of Bacterial Survival, Adherence, and Toxicity.
abstract: In this study we report the underlying reasons to why bacteria are present on banknotes and coins. Despite the use of credit cards, mobile phone apps, near-field-communication systems, and cryptocurrencies such as bitcoins which are replacing the use of hard currencies, cash exchanges still make up a significant means of exchange for a wide range of purchases. The literature is awash with data that highlights that both coins and banknotes are frequently identified as fomites for a wide range of microorganisms. However, most of these publications fail to provide any insight into the extent to which bacteria adhere and persist on money. We treated the various currencies used in this study as microcosms, and the bacterial loading from human hands as the corresponding microbiome. We show that the substrate from which banknotes are produced have a significant influence on both the survival and adherence of bacteria to banknotes. Smooth, polymer surfaces provide a poor means of adherence and survival, while coarser and more fibrous surfaces provide strong bacterial adherence and an environment to survive on. Coins were found to be strongly inhibitory to bacteria with a relatively rapid decline in survival on almost all coin surfaces tested. The inhibitory influence of coins was demonstrated through the use of antimicrobial disks made from coins. Despite the toxic effects of coins on many bacteria, bacteria do have the ability to adapt to the presence of coins in their environment which goes some way to explain the persistent presence of low levels of bacteria on coins in circulation.
authors.affiliation: Department of Food Science and Agri-food Supply Chain Management, Harper Adams University, Newport TF10 8NB, UK. fvriesekoop@harper-adams.ac.uk.|School of Science and Engineering, Federation University, Ballarat 3353, Australia. fvriesekoop@harper-adams.ac.uk.|School of Life Sciences, Heriot Watt University, Edinburgh EH14 4AS, UK. fvriesekoop@harper-adams.ac.uk.
authors.forename: Frank
authors.initials: F
authors.lastname: Vriesekoop
authors.affiliation: School of Science and Engineering, Federation University, Ballarat 3353, Australia. chenjing1983@gmail.com.|College of Life Science and Technology, Beijing University of Chemical Technology, Beijing 100029, China. chenjing1983@gmail.com.
authors.forename: Jing
authors.initials: J
authors.lastname: Chen
authors.affiliation: School of Science and Engineering, Federation University, Ballarat 3353, Australia. j_oldaker_3@hotmail.com.
authors.forename: Jenna
authors.initials: J
authors.lastname: Oldaker
authors.affiliation: Department of Food Science and Agri-food Supply Chain Management, Harper Adams University, Newport TF10 8NB, UK. flbesnard.biotech@gmail.com.
authors.forename: Flavien
authors.initials: F
authors.lastname: Besnard
authors.affiliation: Department of Food Science and Agri-food Supply Chain Management, Harper Adams University, Newport TF10 8NB, UK. reecesmith345@gmail.com.
authors.forename: Reece
authors.initials: R
authors.lastname: Smith
authors.affiliation: School of Science and Engineering, Federation University, Ballarat 3353, Australia. wleversha@bigpond.com.
authors.forename: William
authors.initials: W
authors.lastname: Leversha
authors.affiliation: School of Science and Engineering, Federation University, Ballarat 3353, Australia. Cheralee.Smith-Arnold@sjog.org.au.
authors.forename: Cheralee
authors.initials: C
authors.lastname: Smith-Arnold
authors.affiliation: School of Science and Engineering, Federation University, Ballarat 3353, Australia. j.worrall@federation.edu.au.
authors.forename: Julie
authors.initials: J
authors.lastname: Worrall
authors.affiliation: School of Life Sciences, Heriot Watt University, Edinburgh EH14 4AS, UK. rufrayemilie@yahoo.ca.
authors.forename: Emily
authors.initials: E
authors.lastname: Rufray
authors.affiliation: School of Science and Engineering, Federation University, Ballarat 3353, Australia. yuanqp@mail.buct.edu.cn.|College of Life Science and Technology, Beijing University of Chemical Technology, Beijing 100029, China. yuanqp@mail.buct.edu.cn.
authors.forename: Qipeng
authors.initials: Q
authors.lastname: Yuan
authors.affiliation: College of Life Science and Technology, Beijing University of Chemical Technology, Beijing 100029, China. starslh@163.com.
authors.forename: Hao
authors.initials: H
authors.lastname: Liang
authors.affiliation: College of Life Sciences, University College Dublin, Dublin D04 V1W8, Ireland. amalia.scannell@ucd.ie.
authors.forename: Amalia
authors.initials: A
authors.lastname: Scannell
authors.affiliation: Faculty of Science and Technology, Eastern Institute of Technology, Taradale 4112, New Zealand. CRussell@eit.ac.nz.
authors.forename: Cryn
authors.initials: C
authors.lastname: Russell
keywords: bacteria; banknotes; coins; microbiome; microcosm; substrate