An in vitro phytotoxicity assessment of UV-enhanced biodegradation of plastics for spinach cultivation

Highlights

	● PGPR, Plant growth promoting rhizobacteria was identified as Pseudomonas aeruginosa .
	● Pseudomonas aeruginosa was used to degrade plastic and to enhance plant growth.
	● Biochar was proven as good soil amendment for degradation of microplastic (MPs).
	● P. aeruginosa , biochar and UV rays enhanced plastic degradation and Spinacea oleracea growth.

Abstract

Polyethylene-based plastic mulch films are widely utilized in agriculture due to their benefits in improving soil conditions and crop yield. However, their degradation into microplastics has been shown to negatively impact plant growth and development, posing a significant source of plastic pollution in the agroecosystem. In response to this issue, the present study aimed to design an innovative bioremediation system based on PGPR (Pseudomonas aeruginosa), biochar, and UV treatment for the degradation of plastics. Additionally, the phytotoxic effects of plastic residues on the growth of Spinacia oleracea (spinach) were evaluated to understand the impact of plastic contamination on plant health. Bacterial strains were isolated from vegetable-cultivated soil with plastic mulch. The bacterial strain demonstrating the most effective plant growth-promoting properties and plastic degradation efficiency was identified as Pseudomonas aeruginosa (OP007126). Biochar was prepared from food waste and thoroughly characterized. Polyethylene (PE) was exposed to UV radiation to induce degradation. A glass house experiment was then designed to assess the effect of PGPR, biochar, and UV radiation on mitigating plastic-induced stress and promoting plant growth. Fourier transform infrared spectroscopy (FTIR) and weight loss measurement showed a maximum degradation of 62% with a combination of all treatments. PE negatively affected the morphology of the plant as it decreased the shoot and root fresh weight by up to 60%. Biochemical parameters of spinach were also affected by PE, as proline content increased by up to 45%. The use of amendments demonstrated effectiveness in alleviating the detrimental impact of PE on spinach plants, as evidenced by improvements in morphological, physiologic, and biochemical parameters. This approach presents a promising strategy to mitigate the detrimental effects of plastic mulch and warrants further investigation through field trials.

Graphical abstract

Keywords

Microplastics / Biochar / Degradation / PGPR / UV

References

[1] Abnisa F, Arami-Niya A, Daud W W, Sahu J N. (2013). Characterization of bio-oil and bio-char from pyrolysis of palm oil wastes. BioEnergy Research, 6(2): 830–840

[2] Ábrahám E, Hourton-Cabassa C, Erdei L, Szabados L. (2010). Methods for determination of proline in plants. Methods in Molecular Biology, 639: 317–331

[3] Azeem I, Adeel M, Ahmad M A, Shakoor N, Zain M, Yousef N, Zhao Y, Azeem K, Zhou P, White J C. . (2022). Microplastic and nanoplastic interactions with plant species: trends, meta-analysis, and perspectives. Environmental Science & Technology Letters, 9(6): 482–492

[4] Belzagui F, Buscio V, Gutiérrez-Bouzán C, Vilaseca M. (2021). Cigarette butts as a microfiber source with a microplastic level of concern. Science of the Total Environment, 762: 144165

[5] Biki S P, Mahmud S, Akhter S, Rahman M J, Rix J J, Al Bachchu M A, Ahmed M. (2021). Polyethylene degradation by Ralstonia sp. strain SKM2 and Bacillus sp. strain SM1 isolated from landfill soil site. Environmental Technology & Innovation, 22: 101495

[6] Bostan N, Ilyas N, Akhtar N, Mehmood S, Saman R U, Sayyed R Z, Shatid A A, Alfaifi M Y, Elbehairi S E I, Pandiaraj S. (2023). Toxicity assessment of microplastic (MPs): a threat to the ecosystem. Environmental Research, 234: 116523

[7] BruuinsmaJ (1963). The quantitative analysis of chlorophylls a and b in plant extracts. Photochemistry and Photobiology, 2

[8] Buang Y.. (2013). Antioxidant activities of chloroform and aqueous fractions of myrmecodia pendenss extract: a preliminary study. Journal of Applied Chemical Sciences, 2(1): 187–195

[9] Cafiero L, Fabbri D, Trinca E, Tuffi R, Vecchio Ciprioti S. (2015). Thermal and spectroscopic (TG/DSC–FTIR) characterization of mixed plastics for materials and energy recovery under pyrolytic conditions. Journal of Thermal Analysis and Calorimetry, 121: 1111–1119

[10] Charles J. (2009). Qualitative analysis of high-density polyethylene using FTIR spectroscopy. Asian Journal of Chemistry, 21(6): 4477–4484

[11] Chaudhary K, Chaitanya K, Vijayakumar R P. (2021). Synergistic effect of UV and chemical treatment on biological degradation of polystyrene by Cephalosporium strain NCIM 1251. Archives of Microbiology, 203(5): 2183–2191

[12] Chen Z, Zhao W, Xing R, Xie S, Yang X, Cui P, Lü J, Liao H, Yu Z, Wang S. . (2020). Enhanced in situ biodegradation of microplastics in sewage sludge using hyperthermophilic composting technology. Journal of Hazardous Materials, 384: 121271

[13] Dalvand K, Ghiasvand A. (2019). Simultaneous analysis of PAHs and BTEX in soil by a needle trap device coupled with GC-FID and using response surface me/thodology involving Box-Behnken design. Analytica Chimica Acta, 1083: 119–129

[14] Ding L, Mao R, Ma S, Guo X, Zhu L. (2020). High temperature depended on the ageing mechanism of microplastics under different environmental conditions and its effect on the distribution of organic pollutants. Water Research, 174: 115634

[15] Dubois M L, Gilles J K, Hamilton P A, Smith F. (1951). A calorimetric method for the determination of sugar. Nature, 168: 167

[16] Fotopoulou K N, Karapanagioti H K. (2015). Surface properties of beached plastics. Environmental Science and Pollution Research International, 22(14): 11022–11032

[17] Ghatge S, Yang Y, Ahn J H, Hur H G. (2020). Biodegradation of polyethylene: a brief review. Applied Biological Chemistry, 63(27): 1–14

[18] Giannopolitis C N, Ries S K. (1977). Superoxide Dismutases: I. Occurrence in higher plants. Plant Physiology, 59(2): 309–314

[19] Gong W, Zhang W, Jiang M, Li S, Liang G, Bu Q, Xu L, Zhu H, Lu A. (2021). Species-dependent response of food crops to polystyrene nanoplastics and microplastics. Science of the Total Environment, 796: 148750

[20] Han Y N, Wei M, Han F, Fang C, Wang D, Zhong Y J, Guo C L, Shi X Y, Xie Z K, Li F M. (2020). Greater biofilm formation and increased biodegradation of polyethylene film by a microbial consortium of Arthrobacter sp. and Streptomyces sp. Microorganisms, 8(12): 1979

[21] Hou L, Xi J, Liu J, Wang P, Xu T, Liu T, Qu W, Lin n Y B. (2022). Biodegradability of polyethylene mulching film by two Pseudomonas bacteria and their potential degradation mechanism.. Chemosphere, 286: 131758

[22] Kane S, Van Roijen E, Ryan C, Miller S. (2022). Reducing the environmental impacts of plastics while increasing strength: biochar fillers in biodegradable, recycled, and fossil-fuel-derived plastics. Composites Part C: Open Access, 8: 100253

[23] Keunen E L S, Peshev D, Vangronsveld J, Van Den Ende W I M, Cuypers A N N. (2013). Plant sugars are crucial players in the oxidative challenge during abiotic stress: extending the traditional concept. Plant, Cell & Environment, 36(7): 1242–1255

[24] Kundungal H, Gangarapu M, Sarangapani S, Patchaiyappan A, Devipriya S P. (2019). Efficient biodegradation of polyethylene (HDPE) waste by the plastic-eating lesser waxworm (Achroia grisella). Environmental Science and Pollution Research International, 26(18): 18509–18519

[25] Liu A Y, He Z, Uchimiya M. (2015). Comparison of biochar formation from various agricultural by-products using FTIR spectroscopy. Modern Applied Science, 9(4): 246

[26] Liu H, Weisman D, Ye Y B, Cui B, Huang Y H, Colón-Carmona A, Wang Z H. (2009). An oxidative stress response to polycyclic aromatic hydrocarbon exposure is rapid and complex in Arabidopsis thaliana. Plant Science, 176(3): 375–382

[27] Liu Y, Li R, Yu J, Ni F, Sheng Y, Scircle A, Cizdziel J V, Zhou Y. (2021). Separation and identification of microplastics in marine organisms by TGA-FTIR-GC/MS: a case study of mussels from coastal China. Environmental Pollution, 272: 115946

[28] Mehmood S, Ilyas N, Akhtar N, Chia W Y, Shati A A, Alfaifi M Y, Sayyed R Z, Pusparizkita Y M, Halimatul Munawaroh H S, Quan P M. . (2023). Structural breakdown and phytotoxic assessments of PE degradation through acid hydrolysis, starch addition, and Pseudomonas aeruginosa bioremediation. Environmental Research, 217: 114784

[29] Méndez A, Gómez A, Paz-Ferreiro J, Gascó G. (2012). Effects of sewage sludge biochar on plant metal availability after application to a Mediterranean soil. Chemosphere, 89(11): 1354–1359

[30] Miao Y, Zhang G. (2012). study about characteristics of FTIR and XRD for corn stalk surface with KH-560 treatment. Energy Procedia, 16: 1135–1140

[31] Mochizuki M, Hayashi T, Nakayama K, Masuda T.. (1999). Studies on biodegradable poly (hexane-6-lactone) fibers. Part 2: Environmental degradation. Pure and Applied Chemistry, 71(11): 2177–2188

[32] NabipourZ, Nourbakhsh M S, BaniasadiM (2016). Synthesis, characterization and biocompatibility evaluation of hydroxyapatite-gelatin polyLactic acid ternary nanocomposite. Nanomedicine Journal. 3(2): 127–134

[33] Nair R R, Mondal M M, Weichgrebe D. (2020). Biochar from co-pyrolysis of urban organic wastes: investigation of carbon sink potential using ATR-FTIR and TGA. Biomass Conversion and Biorefinery, 12(10): 4729–4743

[34] Park S Y, Kim C G. (2019). Biodegradation of micro-polyethylene particles by bacterial colonization of a mixed microbial consortium isolated from a landfill site. Chemosphere, 222: 527–533

[35] Porta R. (2021). Anthropocene, the plastic age and future perspectives. FEBS Open Bio, 11(4): 948–953

[36] Qi R, Jones D L, Li Z, Liu Q, Yan C. (2020). Behavior of microplastics and plastic film residues in the soil environment: a critical review. Science of the Total Environment, 703: 134722

[37] Roberts C, Edwards S, Vague M, León-Zayas R, Scheffer H, Chan G, Swartz N A, Mellies J L. (2020). Environmental consortium containing Pseudomonas and Bacillus species synergistically degrades polyethylene terephthalate plastic. MSphere, 5(6): 20–1151

[38] Sa’adu I, Farsang A. (2023). Plastic contamination in agricultural soils: a review. Environmental Sciences Europe, 35(1): 13

[39] Saeed M, Ilyas N, Arshad M, Sheeraz M, Ahmed I, Bhattacharya A. (2021a). Development of plant microbiome bioremediation system for crude oil contamination. Journal of Environmental Chemical Engineering, 9(4): 105401

[40] Saeed M, Ilyas N, Jayachandran K, Gaffar S, Arshad M, Ahmad M, Hessini K. (2021b). Biostimulation potential of biochar for remediating the crude oil contaminated soil and plant growth. Saudi Journal of Biological Sciences, 28(5): 2667–2676

[41] Sakhiya K, Anand A, Kaushal P. (2020). Production, activation, and applications of biochar in recent times. Biochar, 2(3): 253–285

[42] SilvaD, Wiebeck H (2019). Predicting LDPE/HDPE blend composition by CARS-PLS regression and confocal Raman spectroscopy. Polímeros, 29

[43] Soleimani Z, Gharavi S, Soudi M, Moosavi-Nejad Z. (2021). A survey of intact low-density polyethylene film biodegradation by terrestrial Actinobacterial species. International Microbiology, 24(1): 65–73

[44] Sun Y, Shaheen S M, Ali E F, Abdelrahman H, Sarkar B, Song H, Rinklebe J, Ren X, Zhang Z, Wang Q. (2022). Enhancing microplastic biodegradation during composting using livestock manure biochar. Environmental Pollution, 306: 119339

[45] Taghavi N, Zhuang W Q, Baroutian S. (2021). Enhanced biodegradation of non-biodegradable plastics by UV radiation: Part 1. Journal of Environmental Chemical Engineering, 9(6): 106464

[46] Tarchi M, Zaaboub N, Alsubih M, Brik B, Martins M V A, Aleya L, Trabelsi L. (2022). Microalgae colonization and trace element accumulation on the plastisphere of marine plastic debris in Monastir Bay (Eastern Tunisia). Environmental Science and Pollution Research International, 30(12): 32427–32451

[47] Tian L, Jinjin C, Ji R, Ma Y, Yu X. (2022). Microplastics in agricultural soils: sources, effects, and their fate. Current Opinion in Environmental Science & Health, 25: 100311

[48] Tran K M, Lee H M, Thai T D, Shen J, Eyun S I, Na D. (2021). Synthetically engineered microbial scavengers for enhanced bioremediation. Journal of Hazardous Materials, 419: 126516

[49] Wang F, Wang X, Song N. (2021). Polyethylene microplastics increase cadmium uptake in lettuce (Lactuca sativa L.) by altering the soil microenvironment. Science of the Total Environment, 784: 147133

[50] Wani A K, Akhtar N, Naqash N, Chopra C, Singh R, Kumar V, Kumar S, Mulla S I, Américo-Pinheiro J H P. (2022). Bioprospecting culturable and unculturable microbial consortia through metagenomics for bioremediation. Cleaner Chemical Engineering, 2: 100017

[51] Wilamas A, Vinitnantharat S, Pinisakul A. (2023). Manganese adsorption onto permanganate-modified bamboo biochars from groundwater. Sustainability, 15(8): 6831

[52] Wilkes R A, Aristilde L. (2017). Degradation and metabolism of synthetic plastics and associated products by Pseudomonas sp.: capabilities and challenges. Journal of Applied Microbiology, 123(3): 582–593

[53] Wu J, Chen T, Luo X, Han D, Wang Z, Wu J. (2014). TG/FTIR analysis on co-pyrolysis behavior of PE, PVC, and PS. Waste Management, 34(3): 676–682

[54] Yang C, Gao X. (2022). Impact of microplastics from polyethylene and biodegradable mulch films on rice (Oryza sativa L.). Science of the Total Environment, 828: 154579

[55] Yuan J, Ma J, Sun Y, Zhou T, Zhao Y, Yu F. (2020). Microbial degradation and other environmental aspects of microplastics/plastics. Science of the Total Environment, 715: 136968

[56] ZangH, Zhou J, MarshallM R, ChadwickD R, WenY, JonesD L (2020). Microplastics in the agroecosystem: Are they an emerging threat to the plant-soil system? Soil Biology & Biochemistry, 148: 107926

[57] Zhang G, Zhang F, Li X. (2019). Effects of polyester microfibers on soil physical properties: perception from a field and a pot experiment. Science of the Total Environment, 670: 1–7

Acknowledgements

The authors would like to acknowledge the support provided by Researchers Supporting Project Number RSP2024R358, King Saud University, Riyadh, Saudi Arabia.

Conflict of Interests

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Electronic Supplementary Material

Supplementary material is available in the online version of this article at https://doi.org/10.1007/s11783-025-1937-3 and is accessible for authorized users.

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