Besides
the ecotoxicological consequences of microplastics and
associated chemicals, the association of microbes on plastics has
greater environmental implications as microplastics may select for
unique microbiome participating in environmentally significant functions.
Despite this, the functional potential of the microbiome associated
with different types of plastics is understudied. Here, we investigate
the interaction between plastic and marine biofilm-forming microorganisms
through a whole-genome sequencing approach on four types of microplastics
incubated in the marine environment. Taxonomic analysis suggested
that the microplastic surfaces exhibit unique microbial profiles and
niche partitioning among the substrates. In particular, the abundance
of Vibrio alginolyticus and Vibrio campbellii suggested that microplastic pollution
may pose a potential risk to the marine food chain and negatively
impact aquaculture industries. Microbial genera involved in xenobiotic
compound degradation, carbon cycling, and genes associated with the
type IV secretion system, conjugal transfer protein TraG, plant–pathogen
interaction, CusA/CzcA family heavy metal efflux transfer proteins,
and TolC family proteins were significantly enriched on all the substrates,
indicating the variety of processes operated by the plastic–microbiome.
The present study gives a detailed characterization of the rapidly
altering microbial composition and gene pools on plastics and adds
new knowledge surrounding the environmental ramifications of marine
plastic pollution.
Microplastics (MPs) exposed to the
natural environment provide
an ideal surface for biofilm formation, which potentially acts as
a reactive phase facilitating the sorption of hazardous contaminants.
Until now, changes in the contaminant sorption capacity of MPs due
to biofilm formation have not been quantified. This is the first study
that compared the capacity of naturally aged, biofilm-covered microplastic
fibers (BMFs) to adsorb perfluorooctane sulfonate (PFOS) and lead
(Pb) at environmentally relevant concentrations. Changes in the surface
properties and morphology of aged microplastic fibers (MF) were studied
by surface area analysis, infrared spectroscopy, and scanning electron
microscopy. Results revealed that aged MFs exhibited higher surface
areas because of biomass accumulation compared to virgin samples and
followed the order polypropylene>polyethylene>nylon>polyester.
The
concentrations of adsorbed Pb and PFOS were 4–25% and 20–85%
higher in aged MFs and varied among the polymer types. The increased
contaminant adsorption was linked with the altered surface area and
the hydrophobic/hydrophilic characteristics of the samples. Overall,
the present study demonstrates that biofilms play a decisive role
in contaminant-plastic interactions and significantly enhance the
vector potential of MFs for toxic environmental contaminants. We anticipate
that knowledge generated from this study will help refine the planetary
risk assessment of MPs.
The present work was conducted to understand the basis of adaptation in Caragana jubata in its niche environment at high altitude cold desert of Himalaya. Molecular data showed predominance of genes encoding chaperones and those involved in growth and development at low temperature (LT), a major cue operative at high altitude. Importantly, these genes expressed in C. jubata in its natural habitat. Their homologues in Arabidopsis thaliana, Oryza sativa, and Glycine max did not exhibit similar trend of gene expression at LT. Constitutive expression and a quick up-regulation of the above genes suggested the ability of C. jubata to adjust its cellular machinery to maintain growth and development in its niche. This was reflected in LT50 (the temperature at which 50% injury occurred) and LT mediated photosynthetic acclimatory response. Such molecular and physiological plasticity enables C. jubata to thrive in the high altitude cold desert of Himalayas.
The long-term aging of plastic leads to weathering and biofouling that can influence the behavior and fate of plastic in the marine environment. This is the first study to fingerprint the contaminant profiles and bacterial communities present in plastic-associated inorganic and organic matter (PIOM) isolated from 10 year-aged plastic. Plastic sleeves were sampled from an oyster aquaculture farm and the PIOM was isolated from the intertidal, subtidal, and sediment-buried segments to investigate the levels of metal(loid)s, polyaromatic hydrocarbons (PAHs), perfluoroalkyl substances (PFAS) and explore the microbial community composition. Results indicated that the PIOM present on long-term aged high-density polyethylene plastic harbored high concentrations of metal(loid)s, PAHs, and PFAS. Metagenomic analysis revealed that the bacterial composition in the PIOM differed by habitat type, which consisted of potentially pathogenic taxa including Vibrio, Shewanella, and Psychrobacter. This study provides new insights into PIOM as a potential sink for hazardous environmental contaminants and its role in enhancing the vector potential of plastic. Therefore, we recommend the inclusion of PIOM analysis in current biomonitoring regimes and that plastics be used with caution in aquaculture settings to safeguard valuable food resources, particularly in areas of point-source contamination.
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