Plastisphere
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The plastisphere consists of ecosystems that have evolved to live in human-made plastic environments. All plastic accumulated in marine ecosystems serves as a habitat for various types of microorganisms, with the most notable contaminant being microplastics.[1][2] There are an estimate of about 51 trillion microplastics floating in the oceans.[3] Relating to the plastisphere, over 1,000 different species of microbes are able to inhabit just one of these 5mm pieces of plastic.[4]
History
Discovery
The plastisphere was first described by a team of three scientists, Dr. Linda Amaral-Zettler from the Marine Biological Laboratory, Dr. Tracy Mincer from Woods Hole Oceanographic Institution and Dr. Erik Zettler from Sea Education Association.[10][11] They collected plastic samples during research trips to study how the microorganisms function and alter the ecosystem. They analyzed plastic fragments collected in nets from multiple locations within the Atlantic Ocean.[11] The researchers used a combination of scanning electron microscopy and DNA sequencing to identify the distinct microbial community composition of the plastisphere.[11] Among the most notable findings were "pit formers," crack and pit forming organisms that provide evidence of biodegradation.[11][12] Moreover, pit formers may also have the potential to break down hydrocarbons.[11] In their analysis, the researchers also found members of the genus Vibrio, a genus which includes the bacteria that cause cholera and other gastrointestinal ailments.[13] Some species of Vibrio can glow, and it is hypothesized that this attracts fish that eat the organisms colonizing the plastic, which then feed from the stomachs of the fish.[14] Studies carried out in the Baltic Sea[15] and in the Mediterranean Sea,[16] also found microorganisms of the genus Vibrio, in plastic films and fragments, and in plastic fibres, respectively.
Anthropogenic sources
The smaller, more inconspicuous microplastic particles have been aggregating in the oceans since the 1960s.[21] A more recent worry in the pollution of microplastics comes from the use of plastic films in agriculture. 7.4 million tons of plastic films are used each year to increase food production.[22] Scientists have found that microbial biofilms are able to form within 7–14 days on plastic film surfaces, and have the ability to alter the chemical properties of the soil and plants that we are ingesting.[23] Microplastics have been recorded everywhere, even the Arctic due to atmospheric circulation.[24]
Research
Diversity
Large scale sequencing studies have found alpha diversities to be lower in the plastisphere relative to surrounding soil samples due to a decrease in species richness in the plastisphere.[25][26][27][28] Polymer film fragments affect microbes in different ways, leading to mixed effects on microbial growth rates in the plastisphere.[25][28][29] Certain polymer degrading bacteria release toxic byproducts as a result of the degradation of the plant fragment, serving as a deterrent to the colonization of the plastisphere by susceptible species.[25] Phylogenetic diversity is also decreased in the plastisphere relative to nearby soil samples.[25]
The bacterial and microbial communities in the plastisphere are significantly different from those found in surrounding soil samples, creating a new ecological niche within the ecosystem.[25][30][31] The specific growth of bacteria caused by film fragments is a primary cause for the creation of a unique bacterial community.[25][32] Changes in bacterial community composition over time in the plastisphere have also been shown to drive changes in surrounding land.[25][28][33]
In another study which looked at the factors influencing the diversity of the plastisphere, the researchers found that the highest degree of unique microorganisms tended to favor plastic pieces that were blue.[34]
A recent experiment carried across the Atlantic Ocean and the Mediterranean Sea aimed at studying the colonisation and genetic variety of plastics in the marine environment, identified tardigrades in in situincubated plastics for the first time.[35]
Taxonomy
The growth of specific bacteria in their plastisphere occurs because of the ability of certain bacteria to degrade polymers. Phyla of bacteria that have increased presences in the plastisphere relative to soil samples without plastic micro-fragments include
Community metabolism
The metabolism of bacterial communities in the plastisphere are enhanced.
Relationship to carbon, nitrogen, and phosphorus cycling
The presence of hydrocarbon degrading species in the plastisphere proposes a direct link between the plastisphere and the carbon cycle.[25][42][43] Metagenome analyses suggest that genes involved in carbon degradation, nitrogen fixation, organic nitrogen conversion, ammonia oxidation, denitrification, inorganic phosphorus solubilization, organic phosphorus mineralization, and phosphorus transporter production are enriched in the plastisphere, demonstrating the potential impact on biogeochemical cycles by the plastisphere.[25][44][45][46][47][48][49][50] Specific bacterial phyla present in the plastisphere due to their biodegradation abilities and their role in the carbon, nitrogen, and phosphorus cycles include Proteobacteria and Bacteroidetes.[25][42][43][51][52] Some carbon-degrading bacteria are able to use plastics as a food source.[53][54]
Research in the South Pacific Ocean has investigated the plastisphere's potential in CO2 and N2O contribution where fairly low greenhouse gas contributions by the plastisphere were noted. However, it was concluded that greenhouse gas contribution was dependent on the degree of nutrient concentration and the type of plastic.[55]
Significance to human health
KEGG Pathway enrichment analyses of plastisphere samples suggest that sequences related to human disease are enriched in the plastisphere.[25] Cholera causing Vibrio cholerae, cancer pathways, and toxoplasmosis sequences are enriched in the plastisphere.[13][25] Pathogenic bacteria are sustained in the plastisphere in part due to the adsorption of organic pollutants onto biofilms and their usage as nutrition.[25][39][40] Current research also aims to identify the relationship between the plastisphere and respiratory viruses and whether the plastisphere affects viral persistence and survival in the environment.[56]
Degradation by microorganisms
Some microorganisms present in the plastisphere have the potential to degrade plastic materials.[19] This could be potentially advantageous, as scientists may be able to utilize the microbes to break down plastic that would otherwise remain in our environment for centuries.[57] On the other hand, as plastic is broken down into smaller pieces and eventually microplastics, there is a higher likelihood that it will be consumed by plankton and enter into the food chain.[58] As plankton are eaten by larger organisms, the plastic may eventually cause there to be bioaccumulation in fish eaten by humans.[58] The following table lists some microorganisms with biodegradation capacity[19]
Microorganism | Plastic type | Degradation Capacity |
---|---|---|
Aspergillus tubingensis[59] | Polyurethane | Degraded 90% within 21 days[19] |
Pestalotiopsis microspora[60] | Polyurethane | Degraded 90% within 16 days[19] |
Bacillus pseudofirmus[61] | LDPE
|
Degraded 8.3% over 90 day observation period [61] |
Salipaludibacillus agaradhaerens[62] | LDPE
|
Degraded 18.3 ± 0.3% and 13.7 ± 0.5% after 60 days of incubation [62] |
Tenebrio molitor larvae[63] | Polystyrene (PS) | Degradation rates doubled for meal worms with diets that consisted of 10% PS
and 90% bran in comparison to meal worms who were exclusively fed PS[63] |
Enterobacter sp.[19] | Polystyrene (PS) | Degraded a maximum of 12.4% in 30 days [19] |
Phanerochaete chrysosporium[19] | Polycarbonate | Degraded 5.4% in 12 months [19] |
Marine microbial consortium [19] | Polycarbonate | Degraded 8.3% in 12 months [19] |
Ideonella sakaiensis[64] | PET | Fully degraded within six weeks [19] |
Activated sludge[65] | PET | Degraded up to 60% within a year [19] |
Galleria mellonella caterpillars[66] | Polyethylene | Degraded 13% within 14 hours[66] Average degradation rate of 0.23 mg cm-2 h-1[66] |
Zalerium maritimum[67] | Polyethylene | Degraded 70% within 21 days [19] |
Oftentimes the degradation process of plastic by microorganisms is quite slow.[19] However, scientists have been working towards genetically modifying these organisms in order to increase plastic biodegradation potential. For instance, Ideonella sakaiensis has been genetically modified to break down PET at faster rates.[68] Multiple chemical and physical pretreatments have also demonstrated potential in enhancing the degree of biodegradation of different polymers. For instance UV or c-ray irradiation treatments, have been used to heighten the degree of biodegradation of certain plastics.[19]
See also
References
- ^ S2CID 10002632.
- ^ "FAU Scientists Uncover 'Missing' Plastics Deep in the Ocean". www.fau.edu. Retrieved 2023-04-20.
- ^ Zettler E. "The "Plastisphere:" A new marine ecosystem | Smithsonian Ocean". ocean.si.edu. Retrieved 2023-04-20.
- ^ Thomas R (14 June 2021). "Plastic rafting: the invasive species hitching a ride on ocean litter". The Guardian.
- ^ Sahagun L (27 December 2013). "An ecosystem of our own making could pose a threat". Los Angeles Times.
- ^ "Behold the 'Plastisphere'". Consortium for Ocean Leadership. Archived from the original on 2015-11-19. Retrieved 2015-11-18.
- ^ "Scientists Discover Thriving Colonies of Microbes in Ocean 'Plastisphere'". Woods Hole Oceanographic Institution. Retrieved 2015-09-27.
- ^ "Our Trash Has Become A New Ocean Ecosystem Called "The Plastisphere"". Gizmodo. January 2014. Retrieved 2015-10-20.
- S2CID 10002632.
- ^ a b c d e "Behold the 'Plastisphere'". Ocean Leadership. 2015-11-19. Archived from the original on 2015-11-19. Retrieved 2023-04-12.
- ^ Zettler E, Amaral-Zettler L, Mincer T (18 July 2013). "Welcome to The Plastisphere: ocean-going microbes on vessels of plastic". The Conversation. Retrieved 2023-04-12.
- ^ a b "Scientists Discover Thriving Colonies of Microbes in Ocean 'Plastisphere'". Woods Hole Oceanographic Institution. Retrieved 2023-04-12.
- ^ "Glowing Bugs May Lure Fish in the 'Plastisphere'". NBC News. 25 February 2014. Retrieved 2023-04-12.
- PMID 27411093.
- PMID 36449472.
- ^ "The Age of Plastic: From Parkesine to pollution". Science Museum. Retrieved 2023-04-20.
- ^ S2CID 104312770.
- PMID 28776036.
- ^ "International Marine Litter Research Unit". University of Plymouth. Retrieved 2023-04-20.
- S2CID 244942866. Retrieved 2023-04-20 – via FAODocuments.
- PMID 20408641. Retrieved 2023-04-20.
- ^ "Microplastics: what they are and how you can reduce them". www.nhm.ac.uk. Retrieved 2023-04-26.
- ^ PMID 34449345.
- S2CID 10002632.
- S2CID 52945987.
- ^ S2CID 221179856.
- PMID 31441645.
- ISSN 0038-0717.
- S2CID 11935199.
- PMID 25245856.
- PMID 30949147.
- S2CID 221721483.
- PMID 38290365.
- S2CID 105107805.
- S2CID 199507465.
- S2CID 209474917.
- ^ PMID 28514840.
- ^ ISSN 0931-7597.
- PMID 25894657.
- ^ PMID 17014499.
- ^ ISSN 0929-1393.
- S2CID 10672506.
- S2CID 256744433.
- ISSN 0038-0717.
- ISBN 978-1-4020-4019-1
- PMID 21606316.
- PMID 28626450.
- S2CID 208554425.
- PMID 20350306.
- PMID 23663960.
- PMID 21719036.
- PMID 29269847.
- S2CID 209893532.
- S2CID 235198536.
- ^ Davis J (2021-02-10). "How Long Does It Take for Plastic to Decompose?". Chariot Energy. Retrieved 2021-04-16.
- ^ a b "Welcome to The Plastisphere: ocean-going microbes on vessels of plastic". The Conversation. 18 July 2013. Retrieved 2015-11-14.
- ^ Khan, S., Nadir, S., Shah, Z. U., Shah, A. A., Karunarathna, S. C., Xu, J., ... Hasan, F.
(2017). Khan S, Nadir S, Shah ZU, Shah AA, Karunarathna SC, Xu J, Khan A, Munir S, Hasan F (2017-06-01). "Biodegradation of polyester polyurethane by Aspergillus tubingensis". Environmental Pollution. 225: 469–480. PMID 28318785.
- PMID 21764951.
- ^ a b Dela Torre DY, Delos Santos LA, Reyes ML, Baculi RQ (2018). "Biodegradation of low-density polyethylene by bacteria isolated from serpentinization-driven alkaline spring" (PDF). Philippine Science Letters. 11.
- ^ a b Muyot ML, Cada EJ, Sison JM, Baculi RQ (July 2019). "Enhanced in vitro biodegradation of low-density polyethylene using alkaliphilic bacterial consortium supplemented with iron oxide nanoparticles". Philippine Science Letters. 12 – via Research Gate.
- ^ PMID 29145143.
- S2CID 31146235.
- ISSN 0141-3910.
- ^ PMID 28441558.
- PMID 32989159.
Further reading
- "Welcome to the plastisphere". The Economist. 20 July 2013.
- Dunning B (16 December 2008). "Skeptoid #132: The Sargasso Sea and the Pacific Garbage Patch". Skeptoid.
- Dvorsky G (13 November 2013). "New life found on plastic waste gives rise to the 'plastisphere'". io9.
- Marshall M (2 July 2013). "Plastisphere microbes go to sea on flotsam fragments". New Scientist.