Bacterial biofilms colonizing plastics in estuarine waters, with an emphasis on Vibrio spp. and their antibacterial resistance

Abstract

Since plastics degrade very slowly, they remain in the environment on much longer timescales than most natural organic substrates and provide a novel habitat for colonization by bacterial communities. The spectrum of relationships between plastics and bacteria, however, is little understood. The first objective of this study was to examine plastics as substrates for communities of Bacteria in estuarine surface waters. We used next-generation sequencing of the 16S rRNA gene to characterize communities from plastics collected in the field, and over the course of two colonization experiments, from biofilms that developed on plastic (low-density polyethylene, high-density polyethylene, polypropylene, polycarbonate, polystyrene) and glass substrates placed in the environment. Both field sampling and colonization experiments were conducted in estuarine tributaries of the lower Chesapeake Bay. As a second objective, we concomitantly analyzed biofilms on plastic substrates to ascertain the presence and abundance of Vibrio spp. bacteria, then isolated three human pathogens, V. cholerae, V. parahaemolyticus, and V. vulnificus, and determined their antibiotic-resistant profiles. In both components of this study, we compared our results with analyses conducted on paired samples of estuarine water. This research adds to a nascent literature that suggests environmental factors govern the development of bacterial communities on plastics, more so than the characteristics of the plastic substrates themselves. In addition, this study is the first to culture three pathogenic vibrios from plastics in estuaries, reinforcing and expanding upon earlier reports of plastic pollution as a habitat for Vibrio species. The antibiotic resistance detected among the isolates, coupled with the longevity of plastics in the aqueous environment, suggests biofilms on plastics have potential to persist and serve as focal points of potential pathogens and horizontal gene transfer.

Vibrio Colonization Is Highly Dynamic in Early Microplastic-Associated Biofilms as Well as on Field-Collected Microplastics

“…However, several studies have shown that Vibrio is also abundant in young biofilms (≤7 days) on other substrates, such as chitin, fibreglass, wood, glass, or feathers [ 8 , 14 , 51 , 58 , 59 ].…”

“…Following a report of a polypropylene particle from the North Atlantic colonized with a Vibrio strain in high abundance [ 5 ], several studies addressed this issue. Across the world, potentially pathogenic Vibrio species were isolated from plastic debris [ 6 , 7 , 8 ] or detected by specific PCR [ 9 ]. Overall, Vibrio abundances on plastic debris appeared low [ 10 , 11 ], especially when compared to natural particles [ 12 ].…”

Interactions Between Microplastics and Heavy Metals in Aquatic Environments: A Review

“…Many studies have found that the bacterial communities that accumulated on the surface of MPs were more correlated with human disease than in the water column Xue et al, 2020). Laverty et al (2020) isolated three human pathogens from MPs, including Vibrio cholerae, Vibrio parahaemolyticus, and Vibrio traumatica, which may pose a risk to aquatic ecosystems and human health. Presence of heavy metals in waters may exacerbate the risk of microbes to human health, as a study has found that heavy metals (Cu 2+ and Zn 2+ ) significantly increased the horizontal transfer of plasmids in pathogenic bacteria, which may lead to the prevalence of drugresistant pathogenic bacteria in the water environment (Wang et al, 2021c).…”

<em> </em>Current Research on Microbe-Plastic Interactions in the Marine Environment

“…Our knowledge of the functional potential as well as the functional capacity of the plastisphere is currently very limited, although the abilities of plastisphere isolates have been more comprehensively tested. There are just three metagenomic datasets available 12,14,15 as well as several studies that measure one or several aspects of plastisphere function (discussed further below), e.g., alkane degradation 93,94,111 , antimicrobial resistance 26,33,49,56,130,218 or pathogenesis 80,114,138…”

“…Table S4: Potential pathogens (prokaryotic and eukaryotic) found on plastics by the studies reviewed here. Includes references 7,13,26,33,49,56,57,60,69,71,80,83,97,114,127,130,131,137,138,150,362 .…”