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. 2024 Apr 3;17(4):e14457. doi: 10.1111/1751-7915.14457

Assessing microbial plastic degradation requires robust methods

Theo Obrador‐Viel 1,✉, Vinko Zadjelovic 2,3, Balbina Nogales 1, Rafael Bosch 1, Joseph A Christie‐Oleza 1,✉
PMCID: PMC10990042  PMID: 38568802

Abstract

Plastics are versatile materials that have the potential to propel humanity towards circularity and ultimate societal sustainability. However, the escalating concern surrounding plastic pollution has garnered significant attention, leading to widespread negative perceptions of these materials. Here, we question the role microbes may play in plastic pollution bioremediation by (i) defining polymer biodegradability (i.e., recalcitrant, hydrolysable and biodegradable polymers) and (ii) reviewing best practices for evaluating microbial biodegradation of plastics. We establish recommendations to facilitate the implementation of rigorous methodologies in future studies on plastic biodegradation, aiming to push this field towards the use of isotopic labelling to confirm plastic biodegradation and further determine the molecular mechanisms involved.

We question the role microbes may play in plastic pollution bioremediation by (i) defining polymer biodegradability (i.e., recalcitrant, hydrolysable and biodegradable polymers), and (ii) reviewing best practices for evaluating microbial biodegradation of plastics. We establish recommendations to facilitate the implementation of rigorous methodologies in future studies on plastic biodegradation, aiming to push this field towards the use of isotopic labelling to confirm plastic biodegradation and further determine the molecular mechanisms involved.

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THE PROBLEM: PLASTIC POLLUTION AND ITS BIODEGRADABILITY

Since the inception of mass‐production in 1950, 9.2 billion metric tonnes of synthetic polymers have been globally manufactured of which 9% of discarded plastic has been recycled and 12% burned (Rangel‐Buitrago & Neal, 2023). The remaining 79% (approx. 7.2 billion tonnes) has ended in landfills or found its way into natural environments, becoming the legacy of the Anthropocene (Rangel‐Buitrago & Neal, 2023). Plastic pollution is a longstanding concern, with first reports dating back to the early 1970s (e.g., see Carpenter & Smith, 1972; Venrick et al., 1973). The United Nations (UN) has addressed this matter within its Sustainable Development Goals 12 (Responsible Consumption and Production) and 14 (Life Below Water) (United Nations, 2023), aiming to establish a legally binding treaty to tackle plastic pollution (UNEP, 2024). Solutions encompass design, production, waste management and recycling, but plastic inevitably escapes into the environment where it subsequently relies on natural degradation for removal.

Can microbes bioremediate past, present and future plastic pollution? From a microbiological perspective, we will define plastic degradation as the process that leads to polymer scission, assimilation and complete mineralisation of the carbon from the plastic polymer (Oberbeckmann & Labrenz, 2020; Wright et al., 2020). After several decades of research on plastic degradation, the complexity of this process has become increasingly evident since it is hampered by a number of factors – e.g., polymer structure, crystallinity, hydrophobicity or molecular weight (Andrady, 2017; Andrady et al., 2022; Inderthal et al., 2021; Urbanek et al., 2020). One factor that distinctly determines plastic biodegradability is the chemical backbone structure of its polymer. Despite the wide variety of polymer types used in industry (Plastics Europe, 2023), these can be classified as: (i) refractory plastics, made of aliphatic C–C backbones with no weak chemical bond for enzymatic attack (e.g., polyethylene, polypropylene, polystyrene or polyvinyl chloride); (ii) hydrolysable plastics, containing heteroatoms linked by ester bonds that are sterically ‘protected’ from enzymatic cleavage by adjacent aromatic groups (e.g., polyethylene terephthalate, polyurethane or polycarbonates) and (iii) biodegradable plastics, made by aliphatic polyesters highly susceptible to hydrolysis by esterases and other hydrolytic enzymes (e.g., polybutylene succinate, polyhydroxyalkanoates, polylactic acid or polybutylene adipate terephthalate; Figure 1A). Despite the current push for more biodegradable plastics, these still represent under 0.3% of global production, and traditional refractory plastics still make up well over 70% of manufactured plastics (Ellis et al., 2021) (Figure 1B).

FIGURE 1.

FIGURE 1

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Plastic degradability (A) and their corresponding global production (B). Simplified chemical structures of recalcitrant (red), hydrolysable (blue) and biodegradable plastics (green) are indicated. Production of plastics – polypropylene (PP), low‐density and high‐density polyethylene (LD‐ and HD‐PE), polyvinyl chloride (PVC), polystyrene (PS), polyurethanes (PUR), polyethylene terephthalate (PET), acrylonitrile butadiene styrene (ABS), polymethyl methacrylate (PMMA), polytetrafluoroethylene (PTFE), polycarbonates (PC), polytrimethylene terephthalate (PTT), polyamides (PA), polybutylene adipate terephthalate (PBAT), polylactic acid (PLA), polybutylene succinate (PBS) and polyhydroxyalkanoates (PHA) – corresponds to 2022 (Plastics Europe, 2023; European Bioplastics, 2023). Bioplastics are divided between ‘bio‐based’ (traditional non‐degradable plastics synthesised from biological renewable sources) and ‘biodegradable’ (those polymeric materials that can be enzymatically hydrolysed; green).

METHODS TO INVESTIGATE PLASTIC BIODEGRADATION

An increasing volume of literature asserts the biodegradation of various polymer types by diverse microorganisms, indicating a rapidly expanding body of research in this field as reviewed in Chow et al. (2023), Gambarini et al. (2022), Urbanek et al. (2020), Zeghal et al. (2021). Nevertheless, scepticism has raised amongst the scientific community as, in most cases, methods and conclusions are not sufficiently robust. The main reason for such uncertainty resides in the extremely low biodegradation rates of such recalcitrant materials, making unequivocal determinations problematic (Montazer et al., 2020). Table 1 lists the most commonly used methods for assessing microbial plastic degradation. Although these methods have been previously enumerated (Eubeler et al., 2009; Jacquin et al., 2019; Lear et al., 2021; Matjašič et al., 2021; Shah et al., 2008), here we group them as those that assess (i) physicochemical variations of the material and (ii) microbial activity derived from polymer degradation. Most of these techniques work well for determining aliphatic polyester biodegradation, where variations in both polymer scission and microbial growth occur at timescales that allow robust measurements (Table 1). Nevertheless, the biodegradation of recalcitrant C–C backbone polymers occurs at much slower rates and, therefore, more sensitive methods are required to unequivocally assess plastic biodegradation as described in the following sections.

TABLE 1.

Assessment methods for plastic biodegradation and suitability for different polymer types.

Polymer backbone structure a Caveats
[–C(=O)–O–C–] b [–C–C–] c w[–C–C–] d
Physicochemical variations e
Microscopy of surface (SEM, TEM, AFM, EFM) ++ − − Surface imperfections; remaining biofilm; lack of objectivity
Hydrophobicity (contact angle) − + − Remaining biofilm interference; small variations
Tensile strength ++ − − Sample variability; small variations
Polymer size (GPC‐SEC) + + ++ Counterintuitive due to smaller chain degradation; small variations
Thermal analysis (TGA, DSC) + − + Counterintuitive due to smaller chain degradation; small variations
Oxidations (FT‐IR, NMR, XPS, EDS) − ++ + Needs a build‐up of polymer oxidations; remaining biofilm interference
Weight loss +++ − − Small variations; incomplete fragments or powder recovery for weighting
Polymer intermediates (HPLC, MS, GC–MS) +++ − + Requires a build‐up of defined monomers; extraction methods
Microbial activity e
Biofilm formation (FISH, DAPI, others) ++ − + No direct proof of degradation
Microbial growth (OD, protein, cytometry) +++ − +++ Requires degradable materials; degradation time
Carbon consumption (TOC) − − +++ Dependent on the release of dissolved organic carbon
CO2 – O2 evolution (IR, BOD) +++ − +++ Large basal CO2 and O2 variations; small variations; mainly for aerobic deg.
Polymer hydrolysis (Agar clear zone test) +++ − − Difficulty of polymer emulsion in agar; degradation time
Radioactive isotope 14C (CO2, HPLC) +++ +++ +++ Material cost; radioactive hazard during/after handling
Stable isotope 13C (DNA/RNA/lipid‐SIP, nanoSIMS) +++ ++ +++ Material cost; low assimilation rates
Isotopic signature δ13C (IRMS) ++ +++ +++ Requires polymers with low 13C signatures (from fossil fuels)
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a

The validity of each technique for analysing plastic biodegradation has been rates from –, not useful, to +++, very useful.

b

Polyester, including hydrolysable and biodegradable plastics.

c

C–C backbone refractory plastics.

d

Weathered C–C backbone refractory plastics.

e

The techniques employed for each method are denoted in brackets: Scanning electron microscopy (SEM), transmission electron microscopy (TEM), atomic force microscopy (AFM), electrostatic force microscopy (EFM), gel permeation chromatography – size exclusion chromatography (GPC‐SEC), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), Fourier transform – infrared spectroscopy (FT‐IR), nuclear magnetic resonance (NMR), X‐ray photoelectron spectroscopy (XPS), energy‐dispersive X‐ray spectroscopy (EDS), gas‐chromatography (GC), high‐performance liquid chromatography (HPLC), mass spectrometry (MS), fluorescent in situ hybridisation (FISH), 4′,6‐diamidino‐2‐phenylindole staining (DAPI), optical density (OD), total organic carbon (TOC), infrared detector (IR), biological oxygen demand (BOD), stable isotope probing (SIP), nanoscale secondary ion mass spectrometer (nanoSIMS), isotope ratio mass spectrometry (IRMS).

RECOMMENDATIONS FOR MORE ROBUST DETERMINATIONS OF PLASTIC BIODEGRADATION

The methods recommended to study plastic biodegradation will depend on the polymer type and its recalcitrance (Table 1):

  1. Biodegradable plastics (e.g., aliphatic polyesters). As a consequence of their faster degradation rates, these materials exhibit a high degree of compatibility with microbiological processes. Hence, the unequivocal variations in the material's properties (e.g., surface degradation or weight loss), microbial growth or polymer consumption as the sole carbon and energy source can be more easily ascertained. The agar clear zone hydrolysis test – which evaluates enzymatic activity by measuring transparent areas formed around microbial colonies due to substrate degradation – is an ideal strategy to observe not only the hydrolysis of polyesters but also the growth and further isolation of plastic‐degrading microbes (Zadjelovic et al., 2020). Weight loss, CO2 production or O2 consumption has also been successfully applied for biodegradable plastics, further allowing the calculation of degradation rates (Yokoyama et al., 2023).

  2. Hydrolysable plastics (e.g., PET). Despite being polyesters, there are a number of factors that slow down their biodegradation, such as their crystallinity or the presence of aromatic groups in close proximity to the ester bond, altogether hampering hydrolysable plastic biodegradation. While several techniques have shown some effectiveness with these materials (e.g., microbial growth or material's weight loss), the detection of intermediates of polymer degradation or the use of isotopically labelled materials is highly recommendable when studying the biodegradation of such materials (Wright et al., 2021; Yoshida et al., 2016).

  3. Refractory plastics (e.g., C–C backbone polymers). Devoid of hydrolysable chemical bonds and exhibiting exceptionally slow biodegradation rates, the focal point of controversy regarding plastic degradation predominantly centres on these particular materials. Most physicochemical variations in the material are largely negligible and too close to the inherent background noise of each analytical technique. Furthermore, the slow pace of carbon and energy acquisition from plastic biodegradation will primarily be invested in cell maintenance and very little in microbial growth. Hence, we advocate for more sensitive methods when studying refractory plastic biodegradation. While the build‐up of non‐specific surface oxidations – e.g., best detected by Attenuated Total Reflectance Fourier Transform Infrared spectrometry (ATR FT‐IR) – has proven acceptable for initial steps of polymer modification and chain scission, isotopically‐labelled plastics or the acquisition of its isotopic signature are the most powerful methods to unequivocally assess microbial biodegradation (see section below).

  4. Weathered refractory plastics. The initial breakdown of recalcitrant plastics, mainly driven by abiotic processes, occurs through random oxidations that leads to eventual polymer scissions (Bond et al., 2018; Gewert et al., 2018; Hakkarainen & Albertsson, 2004). This process generates a ‘soup’ of oxidised oligomers that requires a specialised metabolism for it to be assimilated and mineralised. As these molecules are readily available for biological uptake, microbial activity can be easily monitored by growth, dissolved organic carbon consumption, CO2 production or O2 consumption. When assessing the physicochemical variations in these materials, counterintuitive results may arise, given that the less degraded or oxidised parts of the polymeric materials tend to persist even after microbial consumption of the oligomers. This may provide contrary results to those expected, e.g., an increase in the average molecular weight can be observed due to the degradation of the shorter fragments.

For any study focused on plastic degradation, it is imperative to employ various cutting‐edge methods regardless of the plastic type under investigation. Most importantly, at least one of these methods should be directed towards determining carbon assimilation and/or mineralisation.

MONITORING PLASTIC BIODEGRADATION VIA ISOTOPIC SIGNATURES

Following the isotopic label of plastics into biological structures or CO2 is a unique strategy for directly assessing the material's assimilation or mineralisation (Montazer et al., 2020; Sander et al., 2019; Wagner & Reemtsma, 2019; Zumstein et al., 2019). Owing to its remarkable sensitivity, this method is gaining rapid popularity amongst researchers engaged in comprehensive studies on recalcitrant plastic biodegradation. Different isotopic labelling options are available, each with their own set of advantages and considerations, as represented in Figure 2A:

  • Radioactive 14 C (and 3 H) labelled plastic. The inclusion of small amounts of radioactive carbon in polymeric materials allows unequivocal measurements of biodegradation. This is due to the extremely high sensitivity of scintillation counters for measuring minute quantities of the radiolabel that may transfer into biomass or respired CO2 (el‐Din Sharabi & Bartha, 1993; Klaeger et al., 2019). Abiotic (Tian et al., 2019) and biotic (Tian et al., 2017) mineralisation of radioactive 14C‐labelled PS has been measured and quantified, as well as the biodegradation of 14C‐labelled PE (Albertsson, 1978; Albertsson & Bánhidi, 1980; Albertson et al., 1978; Sielicki et al., 1978; Tian et al., 2021). The use of 3H‐labelled PE has also been successfully implemented to monitor the degradation of such recalcitrant materials in soils (Anderson et al., 1997). Like any radioactive tracer, radiolabelled plastics pose inherent challenges in terms of synthesis and handling, leading to potential risks of exposure for users. Moreover, these materials are exceptionally costly and present challenges in terms of commercialisation, currently requiring custom‐made polymers with the radioisotope.

  • Stable isotope 13 C‐labelled plastic. Plastics labelled with stable isotopes are safe to handle; however, the material must be almost completely synthesised with 13C to allow a robust tracking of the heavy carbon from the plastic into biomass or CO2. Currently, 99 atom % 13C‐labelled PE is commercially available and partial 13C atom labelled PP and PS can be synthesised on demand. However, these materials come with a hefty price tag, reaching thousands of euros for just a few milligrams (e.g., 2180 € for 100 mg of 99 atom % 13C‐labelled PE in Sigma‐Aldrich®), underscoring the evident constraints associated with such costs. Once the labelled polymer is obtained, a range of cutting‐edge methods can be implemented. First, biodegradation can be confirmed by measuring 13CO2 resulting from plastic mineralisation by using cavity ring‐down spectrometry (CRDS), isotope ratio mass spectrometry (IRMS) or gas chromatography coupled to a quadrupole mass spectrometer/methanizer‐flame ionisation detector (GC–MS/FID) (Goudriaan et al., 2023; Taipale et al., 2019; Yang et al., 2015; Zumstein et al., 2018). On the other hand, the transfer of the 13C from the labelled plastic into biomass such as fatty acids can be detected by standard GC‐IRMS techniques (Goudriaan et al., 2023; Yang et al., 2015) although, theoretically, the incorporation of the heavy carbon into any biological fraction is possible. For example, the transfer of 13C from labelled plastic into microbial DNA not only confirms plastic biodegradation in monocultures but also to identify those members of natural microbial communities that are most efficient in degrading and incorporating the heavy carbon from the plastic – a technique known as DNA‐SIP (Chen & Murrell, 2010). Nevertheless, while DNA or RNA‐SIP has worked well with labile compounds and short incubation times, it remains to be tested with plastics, with the challenge of its slow degradation and assimilation. Finally, direct visualisation of 13C incorporation into cellular biomass has been performed by nanoSIMS, curiously showing that not all the cells of a clonal yeast culture are equally labelled when growing on 13C‐PE (Vaksmaa et al., 2023).

  • 13 C/ 12 C isotopic signature (δ 13 C) of plastic. Here, we further propose tracking the incorporation of the differential isotopic 13C/12C signature (δ13C) of petroleum‐based plastics into microbial biomass as a cheap and reliable alternative method for determining plastic biodegradation (Figure 2A). While the natural distribution of stable carbon isotopes on Earth is 98.9% 12C and 1.1% 13C, organic matter is enriched with 12C due to the selective discrimination exerted by the RuBisCO enzyme against 13CO2. This selective enrichment for 12C is much higher in C3 plants (δ13C between −25 and −35‰) than in C4 plants (δ13C between −10 and −14‰) or CAM plants (δ13C between −10 and −20‰). Fossil fuels –from the Carboniferous (360–300 million years ago) – were generated long before the evolution of C4 plants during the Oligocene (34–23 million years ago) and, hence, have a typical C3 carbon isotopic signature. The δ13C signature has been suggested for tracing bio‐based vs petroleum‐based plastics (Berto et al., 2017; Rogers et al., 2021). We propose measuring the transfer of the light δ13C signature of petroleum‐based plastics into microbial biomass by using IRMS as a simple and cost‐effective method for confirming plastic biodegradation, as demonstrated previously (Zadjelovic et al., 2022) and illustrated in Figure 2B. After all, ‘we are what we eat’.

FIGURE 2.

FIGURE 2

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Isotopic signatures for rigorous monitoring plastic biodegradation. (A) Advantages and disadvantages of using 14C radiolabelled plastics, 13C stable isotope labelled plastics and 13C/12C isotopic signature (δ13C) of fossil fuel‐based plastic for monitoring plastic biodegradation. Techniques used to monitor the transfer of the plastic's isotopic signature into biomass or respired CO2 are indicated. (B) IRMS measurements of the δ13C signatures of Alcanivorax sp. 24 cells grown on different substrates. Cellular biomass acquired the δ13C signature of the source of carbon and energy provided. Pyruvate from two different sources (i.e., Sigma‐Aldrich, presumably from C4 plants, and PanReac AppliChem, from C3 plants) were used as controls, as well as PE and weathered PE plastic pellets (wPE; weathered six months in an oven at 80°C). The pre‐inoculum was grown over 48 h in Marine Broth (MB). It is important to note that the microbial culture used as the inoculum needs to have grown on a carbon source with a heavier δ13C signature than that of fossil fuel‐based plastics to facilitate the visualisation of the acquisition of the plastic signature.

TIPS FOR EXPERIMENTAL DESIGNS AND ROBUST CONTROLS

Given the challenges in accurately detecting and quantifying plastic biodegradation, particular emphasis should be placed on meticulous considerations during the initial stages of experimental design. Here are some critical points:

  • Some mineral media contain carbon‐based buffers that can be used by certain microbes as an undesired carbon source, causing misleading growth that is not based on plastic biodegradation. For example, we have noted that Alcanivorax and Marinobacter strains, and recently published Pseudomonas strains (Holert et al., 2024), can grow on Tris. Preferably, inorganic buffers should be used.

  • Negative controls must always be included (e.g., the inoculum without the plastic and non‐inoculated culture controls). Some studies have, for example, observed a basal CO2 production or increase in culture absorbance that is not caused by the mineralisation of the plastic (Vaksmaa et al., 2023). These and other kinds of ‘false positives’ can be detected by including the proper negative controls. Even including non‐degrading microbes, which are not expected to exert modifications on the plastic, is advisable.

  • Gravimetric weight loss measurements are controversial because variations are often within the experimental error range. Plastics incubated in high salt media can even gain weight, possibly due to the inclusion of salts within micropores. Furthermore, powdered or flaky plastic materials should be avoided as the loss of fragments can be misinterpreted as biodegradation. It is important to note that the maximum percentages of refractory plastic mineralisation calculated with rigorous isotopic‐labelled plastics (0.01%–0.15% weight loss over four‐week incubations) are much lower than those calculated by gravimetric measurements (up to 8%), most probably due to overestimations in the latter (Goudriaan et al., 2023; Mohanan et al., 2020; Priya et al., 2022; Tian et al., 2017; Vaksmaa et al., 2023)

  • Complete removal of microbial biofilms from plastic surfaces is of utmost importance for physicochemical measurements highlighted in Table 1. Any remaining biological material will draw false conclusions on plastic biodegradation such as pits and cracks observed under the microscope, being the biofilm and not the plastic surface what is actually being visualised. Any remaining biofilm will also provide misleading results during hydrophobicity contact angle, thermal or surface oxidation analyses. For example, biological material offers a large variety of new oxidation bonds (e.g., carbonyl or hydroxyl stretches) that will then be misinterpreted as surface oxidations of the plastic when measured by FT‐IR. Therefore, an intensive cleaning after the incubations is needed to remove all organic molecules produced by biofilms. The most advisable methods to ensure a complete removal of the organic matter include (i) the incubation of the plastics in 30% H2O2 and elevated temperatures (Erni‐Cassola et al., 2017) or (ii) a serial rinsing with hot water, ethanol and NaOH (Sandt et al., 2021). Obvious controls are required throughout.

  • The extraction and analytical methods (e.g., chromatography and mass spectrometry analyses) used to study oligomeric intermediates derived from plastic degradation need to be optimised due to the hydrophobicity/hydrophilicity and size of the expected molecules. Controls and blanks are highly relevant due to the presence of background signals that can exist within media and plastic containers used during the processing of samples.

  • Plastics free of additives need to be used to claim polymer biodegradation. User products tend to have a large number and concentration of additives that then provide misleading results. Hence, laboratory‐grade plastics are needed for polymer degradation studies and, still, these may contain small amounts of additives that need to be accounted for with appropriate controls. Manufacturers should be forced to disclose the additives included in plastics.

Whichever the case, if large biodegradation rates are obtained for refractory plastics distrust, revise the experimental design and include robust controls!

THE NEED TO DECIPHER THE MOLECULAR MECHANISMS INVOLVED IN BIODEGRADATION

Once assimilation and mineralisation of plastics have been confirmed, it is critical to explore the cellular mechanisms involved. Whole genome sequencing of microbial isolates, amplicon sequencing and metagenomic analyses of complex microbial communities are now accessible and used in many studies and, to some extent, inform on the metabolic potential within the biological system. Nevertheless, this information is far from pinpointing the actual degradation mechanisms, moreover when most plastic biodegradation enzymes and catabolic pathways are currently unknown, hampering the search. Comparative transcriptomic or proteomics is a step closer to providing hypotheses on the catabolic pathways involved in polymer biodegradation by highlighting upregulated genes/proteins in the presence of the polymeric materials (Gravouil et al., 2017; Zadjelovic et al., 2022; Zampolli et al., 2021). While multi‐omic techniques are becoming more fashionable in plastic‐degradation studies, ultimate proof of the molecular mechanisms can only be achieved by (i) knocking‐out the genes encoding the hypothesised enzymes and observing how the microbe loses the plastic degradation phenotype or (ii) by heterologous expression of these genes in more genetically amendable microbes to confirm the enzymatic activity.

Understanding these mechanisms is indispensable before possibly using biodegradation as an alternative to classical recycling. PET is a clear example, where an explosion of research has taken place in recent years with the discovery of enzymes involved in polymer hydrolysis, i.e., PETases (Yoshida et al., 2016), as well as their enzymatic improvements for the biotechnological application in PET upcycling (Tournier et al., 2020). Heterologous expression of hydrolases is a feasible strategy to enhance degradation of aliphatic polyesters because some of the enzymes are well characterised (Wei & Zimmermann, 2017). But such advances are currently elusive for refractory polymers due to the lack of knowledge of the enzymes involved.

OPEN QUESTIONS

Despite the remarkable growth in research on plastic degradation in recent years, numerous questions persistently linger. Can biodegradable plastics genuinely emerge as a sustainable alternative to their traditional counterparts? What degradation threshold is deemed to be satisfactory? Is enzymatic cleavage a viable solution for recalcitrant plastics? Does the metabolic capability to degrade diverse polymer types truly exist? What characterises the kinetics of plastic biodegradation? The current juncture beckons for a decisive advancement in plastic degradation research, calling for the execution of more intricate experiments that promise more robust, reliable and actionable outcomes.

AUTHOR CONTRIBUTIONS

Theo Obrador‐Viel: Conceptualization; data curation; formal analysis; investigation; visualization; writing – original draft. Vinko Zadjelovic: Data curation; validation; writing – review and editing. Balbina Nogales: Validation; writing – review and editing. Rafael Bosch: Validation; writing – review and editing. Joseph A. Christie‐Oleza: Conceptualization; data curation; funding acquisition; project administration; resources; supervision; validation; visualization; writing – original draft.

CONFLICT OF INTEREST STATEMENT

The authors declare that they have no conflicts of interest.

ACKNOWLEDGEMENTS

This work was supported by the research projects polyDEmar (PID2019‐109509RB‐I00 and PDC2022‐133849‐I00), AlivePlastics (TED2021‐129739B‐I00) and plasticROS (PID2022‐139042NB‐I00) funded by MCIN/AEI/10.13039/501100011033 and EU NextGenerationEU/PRTR. T.O.‐V. was supported by FPU19/05364 contract. V.Z. was supported by ANID‐Subvención a la Instalación en la Academia convocatoria año 2022, Folio 85220034 and FONDECYT de Iniciación en Investigación 2023, N°11230644. J.A.C‐O. was supported by the Ramón y Cajal contract RYC‐2017‐22452 (funded by MCIN/AEI/10.13039/501100011033 and “ESF Investing in your future”).

Obrador‐Viel, T. , Zadjelovic, V. , Nogales, B. , Bosch, R. & Christie‐Oleza, J.A. (2024) Assessing microbial plastic degradation requires robust methods. Microbial Biotechnology, 17, e14457. Available from: 10.1111/1751-7915.14457

Contributor Information

Theo Obrador‐Viel, Email: theo.obrador@uib.cat.

Joseph A. Christie‐Oleza, Email: joseph.christie@uib.eu.

DATA AVAILABILITY STATEMENT

All data is available on request.

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