@conference{
author = "de Guzman, Maria Krishna and Wimmer, Lukas and Dailey, Lea Ann and Van Haute, Sam and Ćirković-Veličković, Tanja",
year = "2022",
abstract = "The prevalence of microplastics (MP) pollution in
different zones of the environment has been
established by several studies [1]. Due to its
widespread presence, MP have found its way into
food items. Fish, shellfish, water, milk, salt, and
sugar are just some examples of the food we
commonly consume that are contaminated with MP
[2]. Human ingestion of MP is already well-established
but there is limited data regarding how
MP affect human gastric digestion of food
components, especially proteins.
In this study, we investigated the effects of
polystyrene (PS) MP on pepsin, the major protease
in human gastric digestion. Pepsin activity was
tested during exposure to two different sizes -10 μm
(PS10) and 100 μm (PS100), and three different
quantities- low count (142 particles), moderate
count (1420 particles), and high count
(14200 particles), of PS using haemoglobin as
substrate. Results showed that exposure to PS100
has no effect on enzyme activity. However,
exposure to high count PS10 considerably reduced
pepsin activity from 2957 ± 310 U/mg to 1674 ± 270
U/mg.
To test the effect on food digestion, high count
PS10 was added to a sample of commercially
available liquid bovine milk (defatted). In this case,
the static in vitro simulation of gastric digestion was
followed to mimic human digestion of food [3].
Milk digesta at different time points (5, 10, 15, 20,
30, 60, 90, 120 minutes) were obtained to monitor
the progress of protein degradation.
SDS-PAGE showed no difference in the peptide
bands from 30-120 minutes. However, bands
corresponding to caseins were not observed at 5
minutes when PS10 was present. Additionally,
14 kDa fragments were not observed at 10-20
minutes.
Washing of the PS particles followed by SDSPAGE
revealed a faint pepsin band from all time
points. At 5 and 10 minutes, faint peptide bands
>10kDa were also observed. These suggest that
pepsin and some milk peptides were adsorbed on
the surface of PS10. Zeta potential analysis of PS
revealed a slightly negative surface charge which
could explain the adsorption and disappearance of
peptide bands. This adsorption of pepsin on PS did
not seem to affect its overall protease activity.
However, the interaction of milk peptides with PS
may reduce the nutrients human could acquire from
milk.
Acknowledgements
This study was supported by Ghent University
Global Campus; Special Research Fund (BOF) of
Ghent University (grant number 01N01718) and
IMPTOX European Union’s Horizon 2020 research
and innovation program (grant number 965173).
References
[1] S. Sharma, S. Basu, N. P. Shetti, M. N. Nadagouda, T.
M. Aminabhavi (2021) Chem. Eng. J., 408, 127317.
[2] K. D. Cox, G. A. Covernton, H. L. Davies, J. F. Dower,
F. Juanes, S. E. Dudas (2019) Environ. Sci. Technol.,
53(12), 7068–7074.
[3] A. Brodkorb et al. (2019) Nat. Protoc., 14(4), 991–
1014.",
publisher = "University of Ljubljana Press",
journal = "Book of Abstracts of the 22nd European Meeting on Environmental Chemistry, Ljubljana, Slovenia, 5-8 December 2022",
title = "Implications of Polystyrene Microplastics on the Gastric Digestion of Bovine Milk",
pages = "124-124",
url = "https://hdl.handle.net/21.15107/rcub_cherry_5908"
}
