Where Have You Been? Backtracking Microplastic to Its Source Using the Biomolecular Composition of the Ecocorona

Microplastics are
a diffuse contaminant with various global sources,
pathways, and sinks. This study aimed to backtrack microplastics across
environments using metaproteomic and eDNA metabarcoding information
stored within the ecocorona. Pristine polyamide (PA) fibers, polyethylene
terephthalate (PET) fibers and fragments, and PET and PA preincubated
in bovine serum albumin (BSA) were deployed into a tank housing Penaeus monodon to develop an ecocorona. Upon collection,
BSA was detected within the ecocorona, along with P. monodon proteins, using mass spectrometry. BSA preincubation influenced
the diversity and abundance of ecocorona proteins with pristine microplastics
having more significantly enriched proteins. Most ecocorona proteins
reflected the marine environment, confirming that the protein assemblage
on microplastics records environmental signatures. Microplastic tracking
was validated using polyethylene plastics unintentionally discharged
from an aquaculture facility into Moreton Bay and collected after
7 days. Orthogonal Partial Least Square models predicted the source
with 69–92% accuracy based on 16S eDNA taxa and 69–123%
accuracy based on untargeted metaproteomics. Several identified taxa
from both analyses were specific to the aquaculture source, including
genera Leucothrix and Rugeria and
species Salmo salar and P. monodon. Overall tracking of microplastics using the ecocorona proved effective
over short time scales and reliably reflected the surrounding biological
milieu.