Biodegradability Of Polylactic Acid Research Articles

Studies on parametric optimization of PLA/graphene composites synthesized by fused filament fabrication for thermal applications

The objective of this study is to examine the impact of various material and processing factors on the hardness (Shore D) and tensile strength of PLA/graphene composites. The study employed the Taguchi method to systematically optimize and statistically analyze various process variables, including the content of graphene (0 %, 0.5 %, and 1.0 % by weight), infill density (80 %, 90 %, and 100 %), and print speed (160 mm/s, 170 mm/s, and 180 mm/s). The composite material was fabricated utilizing the fused filament fabrication (FFF) technique, employing polylactic acid (PLA) and graphene as the primary feedstock materials. A standardized experiment was conducted in accordance with ASTM standards to assess the hardness and strength of samples that were prepared based on the experimental design. Based on the S/N ratio response table, it can be concluded that the reinforcement content is the most significant factor affecting both hardness and tensile strength. The optimal combination of process variables for achieving high hardness and tensile strength was found to be a graphene content of 1 %, an infill density of 100 %, and a print speed of 180 mm/s. The analysis of variance (ANOVA) indicated that the variable with the greatest statistical significance and substantial impact on the properties is the content of reinforcement. The analysis of fractures indicated a transition from ductile to brittle behavior with an increase in infill density. Furthermore, both composites demonstrated a brittle mode of failure irrespective of the infill density. Thus this composite material synergistically combines the inherent biodegradability of PLA with the improved thermal conductivity of graphene.

Dyeability and hydrolytic degradation of polylactic acid fibers under different environments

Polylactic acid (PLA), a biodegradable material derived from industrial crops such as corn and straw, is increasingly recognized in various sectors, including textiles, food, and medicine. However, the dyeability and biodegradability of PLA a key factor contributing to its growing popularity. Herein, we report a sustainable dyeing method for the coloration of PLA fibers with excellent fastness using dispersed dyes. The results showed that the dyed PLA fabric exhibited a K/S value of 8.4, along with impressive grade 4 fastness to both dry and wet rubbing. Additionally, the dyed PLA fabric exhibited increased hydrophilicity and enhanced surface roughness. Most importantly, during the hydrolytic degradation experiment, the dyed polylactic acid fabric experienced a notable 36 % decrease in quality when exposed to a water environment characterized by a pH of 11, a temperature of 40 °C, and a duration of 60 days, whereas the control PLA fabric is only 8 %. The hydrolytic degradation of PLA occurs at its fastest rate when the color of the dye is at its optimal intensity, the environmental temperature is elevated, and the pH level is in an alkaline state. The degradation rate of PLA fabric initially tends to be rapid, followed by a gradual slowdown. This research may provide a useful guideline for the proper storage of dyed PLA fabrics and their use in the textile industry.

Effects of turning aeration and the initial carbon/nitrogen ratio on the biodegradation of polylactic acid under controlled conditions

Plastic pollution is primarily caused by the accumulation of petroleum-derived plastics, as they tend to degrade slowly. Sustainable alternatives to these materials are bio-based and biodegradable plastics, such as polylactic acid (PLA). In this study, we assessed how turning aeration and the initial carbon/nitrogen (C/N) ratio impact PLA biodegradation. The study was carried out under controlled composting conditions, over 180 days, with the aim of decreasing the biodegradation time of the PLA. Apple pomace, rice husk, grape pomace compost, and PLA were used as substrates in the composting process. The experiments were conducted using three types of turning aeration: without turning, one turn per week, and two turns per week. Three initial C/N ratios were used: 20, 30, and 40. A stepwise temperature ramp was designed and implemented to simulate industrial composting conditions, which influence microbial activity and thus the rate of decomposition of substrates, including PLA. The data showed behavior; hence, a nonlinear regression model based on the logistic growth equation was used to predict the PLA biodegradation at the end of the composting process. The results showed that two turns per week with an initial C/N ratio of 30 or 40 led to a 90 % biodegradation of the PLA in 130 days. This degradation was verified by Fourier-Transform Infrared Spectroscopy (FTIR) and Scanning Electron Microscopy (SEM).

Novel methods to monitor the biodegradation of polylactic acid (PLA) by Amycolatopsis orientalis and Amycolatopsis thailandensis.

Plastics are essential in modern life, but their conventional production is problematic due to environmental pollution and waste management issues. Polylactic acid (PLA) is a widely used bioplastic that is bio-based and biodegradable, making it a key player in the bioeconomy. PLA has been proven to be degradable in various settings, including aqueous, soil, and compost environments. However, monitoring and optimizing PLA biodegradation remains challenging. This study proposes methods to improve the quantification of PLA biodegradation by Amycolatopsis spp. Ultrasound treatments (10s) significantly improved the enumeration of viable Amycolatopsis cells by breaking the pellets into quantifiable individual cells. A separation technique combining ultrasound (120s) and 40μm cell strainers effectively isolated PLA particles from biomass to quantify PLA weight loss. This enabled the monitoring of PLA biofragmentation. Finally, CO2 production was measured according to ISO 14852 to quantify mineralization. Integrating these methods provides an improved quantification for PLA biodegradation along its different stages. In a case study, this led to the construction of a carbon balance where 85.1% of initial carbon content was successfully tracked. The developed techniques for monitoring of PLA biodegradation are essential to design future waste management strategies for biodegradable plastics.

A natural butter glyceride as a plasticizer for improving thermal, mechanical, and biodegradable properties of poly(lactide acid)

Polylactic acid (PLA) is a biobased and biodegradable thermoplastic polyester with great potential to replace petroleum-based plastics. However, its poor toughness and slow biodegradation rate affect broad applications of PLA in many areas. In this study, a glycerol triester existing in natural butter, glycerol tributyrate, was creatively explored and compared with previously investigated triacetin and tributyl citrate, as potential plasticizers of PLA for achieving improved mechanical and biodegradation performances. The compatibilities of these agents with PLA were assessed quantitively via the Hansen solubility parameter (HSP) and measured by using different testing methods. The incorporation of these compounds with varied contents ranging from 1 to 30 % in PLA altered thermal, mechanical, and biodegradation properties consistently, and the relationship and impacts of chemical structures and properties of these agents were systematically investigated. The results demonstrated that glycerol tributyrate is a novel excellent plasticizer for PLA and the addition of this triester not only effectively reduced the glass transition, cold crystallization, and melting temperatures and Young's modulus, but also led to a significant improvement in the enzymatic degradation rate of the plasticized PLA. This study paves a way for the development of sustainable and eco-friendly food grade plasticized PLA products.

Glycerol-derived organic carbonates: environmentally friendly plasticizers for PLA.

Polylactic acid (PLA) stands as a promising material, sourced from renewables and exhibiting biodegradability-albeit under stringent industrial composting settings. A primary challenge impeding PLA's broad applications is its inherent brittleness, as it fractures with minimal elongation despite its commendable tensile strength. A well-established remedy involves blending PLA with plasticizers. In this study, a range of organic carbonates-namely, 4-ethoxycarbonyloximethyl-[1,3]dioxolan-2-one (1), 4-methoxycarbonyloximethyl-[1,3]dioxolan-2-one (2), glycerol carbonate (3), and glycerol 1-acetate 2,3-carbonate (4)-were synthesized on a preparative scale (∼100 g), using renewable glycerol and CO2-derived diethyl carbonate (DEC) or dimethyl carbonate (DMC). Significantly, 1-4 exhibited biodegradability under ambient conditions within a week, ascertained through soil exposure at 25 °C-outpacing the degradation of comparative cellulose. Further investigations revealed 1's efficacy as a PLA plasticizer. Compatibility with PLA, up to 30 phr (parts per hundred resin), was verified using an array of techniques, including DSC, DMA, SEM, and rotational rheometry. The resulting blends showcased enhanced ductility, evident from tensile property measurements. Notably, the novel plasticizer 1 displayed an advantage over conventional acetyltributylcitrate (ATBC) in terms of morphological stability. Slow crystallization, observed in PLA/ATBC blends over time at room temperature, was absent in PLA/1 blends, preserving amorphous domain dimensions and mitigating plasticizer migration-confirmed through DMA assessments of aged and unaged specimens. Nevertheless, biodegradation assessments of the blends revealed that the biodegradable organic carbonate plasticizers did not augment PLA's biodegradation. The PLA in the blends remained mostly unchanged under ambient soil conditions of 25 °C over a 6 month period. This work underscores the potential of organic carbonates as both eco-friendly plasticizers for PLA and as biodegradable compounds, contributing to the development of environmentally conscious polymer systems.

Polylactic acid films reinforced with chitin nanocrystals: Biodegradation and migration behavior

Polylactic acid (PLA) is a widely recognized sustainable alternative to conventional petroleum-based plastics for food packaging. To enhance its properties that currently trail those of conventional packaging materials, the addition of chitin nanocrystals (ChNC) has been considered. This has led, amongst others to stronger materials. For their ultimate application, it is also important to evaluate these materials in terms of food safety and environmental impact. In this study, we investigate the biodegradation of and migration from ChNC/PLA nanocomposites. The solution casting method was used to prepare PLA and ChNC/PLA nanocomposites, and overall migration (OM) tests were carried out with food simulants (10 % ethanol and isooctane). Additionally, we evaluated the biodegradability (crude chitin powder, ChNC, and nanocomposites) based on ISO norm no 14851:2019. The OM tests demonstrated that the migration levels from ChNC-PLA composites were below the allowed limit (60 mg/kg). The biodegradability of ChNC was comparable to that of crude chitin powder and microcrystalline cellulose, and interestingly, when incorporated in PLA films did not impact the biodegradability of PLA in a negative way. In summary, the migration and biodegradation of ChNC/PLA nanocomposites exhibit encouraging potential for their future utilization in food packaging.

UV Light Degradation of Polylactic Acid Kickstarts Enzymatic Hydrolysis.

Polylactic acid (PLA) and bioplastics alike have a designed degradability to avoid the environmental buildup that petroplastics have created. Yet, this designed biotic-degradation has typically been characterized in ideal conditions. This study seeks to relate the abiotic to the biotic degradation of PLA to accurately represent the degradation pathways bioplastics will encounter, supposing their improper disposal in the environment. Enzymatic hydrolysis was used to study the biodegradation of PLA with varying stages of photoaging. Utilizing a fluorescent tag to follow enzyme hydrolysis, it was determined that increasing the amount of irradiation yielded greater amounts of total enzymatic hydrolysis by proteinase K after 8 h of enzyme incubation. While photoaging of the polymers causes minimal changes in chemistry and increasing amounts of crystallinity, the trends in biotic degradation appear to primarily be driven by photoinduced reduction in molecular weight. The relationship between photoaging and enzyme hydrolysis appears to be independent of enzyme type, though commercial product degradation may be impacted by the presence of additives. Overall, this work reveals the importance of characterizing biodegradation with relevant samples that ultimately can inform optimization of production and disposal.

Identification of a plastic-degrading enzyme from Cryptococcus nemorosus and its use in self-degradable plastics.

For decades, plastic waste management has been one of the major ecological challenges of our society. Despite the introduction of biodegradable alternatives such as polylactic acid (PLA), their beneficial environmental impact is limited by the requirement of specific compost facility as biodegradation of PLA in natural environment occurs at a very slow rate. In this work, a plastic-degrading enzyme was utilized to facilitate degradation process. Genomic and proteomic tools were employed to identify a new biodegradable plastic-degrading enzyme from Cryptococcus nemorosus TBRC2959. The new enzyme, Cr14CLE, functions optimally under mild conditions with temperature range of 30 to 40°C and suffers no significant loss of enzymatic activity at pH ranging from 6 to 8. In addition to PLA, Cr14CLE is capable to degrade other types of biodegradable plastic such as polybutylene succinate (PBS) and polybutylene adipate terephthalate (PBAT) as well as composite bioplastic. Applications of Cr14CLE have been demonstrated through the preparation of enzyme-coated PLA film and laminated PLA film with enzyme layer. PLA films prepared by both approaches exhibited capability to self-degrade in water. KEY POINTS: • Novel plastic-degrading enzyme (Cr14CLE) was identified and characterized. • Cr14CLE can degrade multiple types of biodegradable plastics under mild conditions. • Applications of Cr14CLE on self-degradable plastic were demonstrated.

Evaluation of bioplastics biodegradation under simulated landfill conditions.

Bioplastics that are generated from renewable sources have been regarded as an alternative to conventional plastics. Polylactic acid (PLA) is one of the mostly produced bioplastics because of its long shelf life for various applications. Even though bioplastics have drawn attention recently, their ultimate fate in landfills is still unknown. In this study, a standardized laboratory-scale lysimeter experiment was performed for the simulation of landfill conditions in order to evaluate the biodegradability of PLA during municipal solid waste stabilization. The reactors were loaded with municipal solid waste (MSW) taken from an operating landfill, certified PLA cups, and seed sludge. Various phases of landfill stabilization were simulated; hence, the reactors were operated under aerobic, semi-aerobic, and anaerobic conditions, respectively. Throughout the operation, both leachate and biogas generation in the reactors were regularly monitored. At the end of each phase, bioplastic cups were removed from the reactors, gently cleaned, weighed, and examined under a scanning electron microscope (SEM). The experimental results indicated that bioplastics did not undergo significant biodegradation during the first two stabilization phases (aerobic and semi-aerobic). On the other hand, it was observed that the cups were much softer and whiter at the end of the anaerobic phase. The weight of cups decreased by 12.8% on average, and their surfaces were prominently damaged after the completion of the last phase indicating the potential signs of biodegradation.

Mechanical properties of Biodegradable Composite Developed by Modification of Poly lactic Acid with Orange Peel Powder

<p>One of the biggest environmental issues has been the use and disposal of traditional fossil-based plastic, which is not biodegradable and uses a lot of energy in its production. Poly lactic acid (PLA) has received a lot of attention as an environmentally friendly substitute due to the fact that it is a renewable polymer made from natural sources with qualities equivalent to traditional plastics and minimal environmental cost. Orange peel waste is abundantly produced and contains many important components, but its prospective uses in fortifying the PLA matrix have received little attention. Synthesized from dried orange peel waste, orange peel powder (OP) was added to PLA solution in this investigation. Finally, thin films were produced using the solution casting method from PLA/OP solutions with varying OP loadings (0, 10, 20, 40, and 60 wt%). The addition of OP to PLA has reduced its tensile strength and Young's modulus, but has increased its elongation at break by 49–737%, as shown by tensile test results. Analyses of water contact angles reveal that hydrophilic OP has altered the hydrophobicity of PLA's surface, with contact angles ranging from 70.120 to 88.180: nevertheless, greater loadings result in a reduction in surface energy. After 28 days, the PLA/60 wt% OP composite has the highest biodegradation performance, with a weight loss of 59.43%. This suggests that the inclusion of OP enhances the biodegradability of PLA.</p>

Synthesis of a new biocomposite for fertiliser coating: assessment of biodegradability and thermal stability

The bio- and thermal degradation as well as the water absorption properties of a novel biocomposite comprising cellulose nanoparticles, natural rubber and polylactic acid have been investigated. The biodegradation process was studied through an assembled condition based on the soil collected from the central Malaysian palm oil forests located in the University of Nottingham Malaysia. The effects of the presence of the cellulose nanoparticles and natural rubber on the biodegradation of polylactic acid were investigated. The biodegradation process was studied via thermal gravimetric analysis and scanning electron microscopy. It was understood that the reinforcement of polylactic acid with cellulose nanoparticles and natural rubber increases the thermal stability by ~ 20 °C. Limited amorphous regions on the surface of the cellulose nanoparticles accelerated the biodegradation and water absorption processes. Based on the obtained results, it is predicted that complete biodegradation of the synthesised biocomposites can take place in 3062 h, highlighting promising agricultural applications for this biocomposite.

Transcriptomic analysis of PLA-degrading bacteria Brevibacillus brevis grown on polylactic acid

Polylactic acid (PLA) is a promising biodegradable material used in various fields, such as mulching films and disposable packaging materials. Biological approaches for completely degrading biodegradable polymers can provide environmentally friendly solutions. However, to our knowledge, no studies have performed transcriptome profiling to analyze PLA-degrading genes of PLA-degrading bacteria. Therefore, this study reports for the first time an RNA sequence approach for tracing genes involved in PLA biodegradation in the PLA-degrading bacterium Brevibacillus brevis. As a result, the hydrolase genes (mhqD, nap, and besA) were mainly up-regulated, indicating that the hydrolase plays a key role in the biodegradation of PLA by B. brevis. In addition, genes involved in biofilm formation and transporter genes were also up-regulated. Taken together, genes related to biofilm formation were up-regulated for access to PLA and biodegradation, and hydrolase genes were up-regulated to degrade PLA into lactic acid oligomers and monomers. Finally, transport-related genes were up-regulated for cellular assimilation of the degraded oligomers. Our results provide transcriptome-based insights into the biodegradation mechanism of PLA, which pitches a better understanding of microbial biodegradation of plastics.

Biodegradation of polylactic acid by a mesophilic bacteria Bacillus safensis

A mesophilic bacterial strain, Bacillus safensis PLA1006, was isolated from landfill soil and was tested for growth on polylactic acid (PLA) emulsion medium. The strain formed clear zones on the medium and produced protease and lipase. The macroscopic morphology of the PLA films was not changed significantly after treatment with Bacillus safensis PLA1006 but the films were whitened. Weight loss of PLA films was about 8% after 30 days of incubation with Bacillus safensis PLA1006 in mineral salt medium. Scanning electron microscopy revealed etching on the surface of PLA film treated by Bacillus safensis PLA1006. This also caused an increase in hydrophilicity of the PLA films surface. Attenuated total reflectance - Fourier transform infrared spectroscopy analysis of PLA films after treated by Bacillus safensis PLA1006 showed no new absorption peaks but a decrease in the intensity of all absorption peaks. The hydrolysis products of PLA by the strain contained monomers and oligomers of lactic acid. Zymogram detection showed that proteases may play a role in the degradation of PLA.

Biodegradable PLA-ZnO nanocomposite biomaterials with antibacterial properties, tissue engineering viability, and enhanced biocompatibility

Polylactic acid (PLA) is a well-known biomaterial on account of its biocompatibility and biodegradability. Zinc oxide (ZnO) nanofillers may endow PLA with advantageous antibacterial and tissue regenerative properties, but may also compromise the biocompatibility of PLA. Several strategies have been developed to improve the biomedical practicality of such composites. The importance of surface properties on amplifying the therapeutic properties and safety of a material enables two potential strategies: (i) surface modification of ZnO nanoparticles, and (ii) surface engineering of the PLA/ZnO composites. Moreover, the controllable biodegradation of PLA allows a third possible strategy: (iii) biodegradation-controlled release of ZnO. The first part of this review introduces the controllable degradation of PLA and the mechanisms of therapeutic properties and cytotoxicity of ZnO. Following this, the paper highlights current research trends regarding the biomedical application of PLA-based ZnO nanocomposites. The final section of this review discusses the potential use of ZnO in tuning the degradation rate of PLA, and the possibility of manipulating the surface properties of ZnO nanoparticles and PLA/ZnO composites in order to optimize the therapeutic properties and safe usage of PLA/ZnO composites in the biomedical field.

Genome sequence analysis and characterization of Bacillus altitudinis B12, a polylactic acid- and keratin-degrading bacterium.

Keratin-rich wastes, mainly in the form of feathers, are recalcitrant residues generated in high amounts as by-products in chicken farms and food industry. Polylactic acid (PLA) is the second most common biodegradable polymer found in commercial plastics, which is not easily degraded by microbial activity. This work reports the 3.8-Mb genome of Bacillus altitudinis B12, a highly efficient PLA- and keratin-degrading bacterium, with potential for environmental friendly biotechnological applications in the feed, fertilizer, detergent, leather, and pharmaceutical industries. The whole genome sequence of B. altitudinis B12 revealed that this strain (which had been previously misclassified as Bacillus pumilus B12) is closely related to the B. altitudinis strains ER5, W3, and GR-8. A total of 4056 coding sequences were annotated using the RAST server, of which 2484 are core genes of the pan genome of B. altitudinis and 171 are unique to this strain. According to the sequence analysis, B. pumilus B12 has a predicted secretome of 353 proteins, among which a keratinase and a PLA depolymerase were identified by sequence analysis. The presence of these two enzymes could explain the characterized PLA and keratin biodegradation capability of the strain.

The Influence of Plasticizers and Accelerated Ageing on Biodegradation of PLA under Controlled Composting Conditions

The overall performance of plasticizers on common mechanical and physical properties, as well as on the processability of polylactic acid (PLA) films, is well-explored. However, the influence of plasticizers on biodegradation is still in its infancy. In this study, the influence of natural-based dicarboxylic acid-based ester plasticizers (MC2178 and MC2192), acetyl tributyl citrate (ATBC Citroflex A4), and polyethylene glycol (PEG 400) on the biodegradation of extruded PLA films was evaluated. Furthermore, the influence of accelerated ageing on the performance properties and biodegradation of films was further investigated. The biodegradation of films was determined under controlled thermophilic composting conditions (ISO 14855-1). Apart from respirometry, an evaluation of the degree of disintegration, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FT-IR), and scanning electron microscopy (SEM) of film surfaces was conducted. The influence of melt-processing with plasticizers has a significant effect on structural changes. Especially, the degree of crystallinity has been found to be a major factor which affects the biodegradation rate. The lowest biodegradation rates have been evaluated for films plasticized with PEG 400. These lower molecular weight plasticizers enhanced the crystallinity degrees of the PLA phase due to an increase in chain mobility. On the contrary, the highest biodegradation rate was found for films plasticized with MC2192, which has a higher molecular weight and evoked minimal structural changes of the PLA. From the evaluated results, it could also be stated that migration of plasticizers, physical ageing, and chain scission of films prompted by ageing significantly influenced both the mechanical and thermal properties, as well as the biodegradation rate. Therefore, the ageing of parts has to be taken into consideration for the proper evolution of the biodegradation of plasticized PLA and their applications.

Thermomechanical Properties and Biodegradation Behavior of Itaconic Anhydride-Grafted PLA/Pecan Nutshell Biocomposites.

The use of lignocellulose-rich biowaste as reinforcing filler in biodegradable polymers represents a sustainable option to obtain cost-effective bio-based materials to be used for several applications. In addition, the scarce polymer-biofiller interaction can be improved by reactive functionalization of the matrix. However, the obtained biocomposites might show high thermal deformability and possibly a slow biodegradation rate. In this work, polylactic acid (PLA) was first chemically modified with itaconic anhydride, and then biocomposites containing 50 wt.% of pecan (Carya illinoinensis) nutshell (PNS) biowaste were prepared and characterized. Their physical and morphological properties were determined, along with their biodegradation behavior in soil. Moreover, the effects of two environmentally friendly physical treatments, namely ball-milling of the filler and thermal annealing on biocomposites, were assessed. Grafting increased PLA thermal-oxidative stability and crystallinity. The latter was further enhanced by the presence of PNS, achieving a 30% overall increase compared to the plain matrix. Accordingly, the biocomposites displayed mechanical properties comparable to those of the plain matrix. Thermal annealing dramatically increased the mechanical and thermomechanical properties of all materials, and the heat deflection temperature of the biocomposites dramatically increased up to 60 °C with respect to the non-annealed samples. Finally, PNS promoted PLA biodegradation, triggering the swelling of the composites under soil burial, and accelerating the removal of the polymer amorphous phase. These results highlight the potential of combining natural fillers and environmentally benign physicochemical treatments to tailor the properties of PLA biocomposites. The high biofiller content used in this work, in conjunction with the chemical and physico-mechanical treatments applied, increased the thermal, mechanical, and thermomechanical performance of PLA biocomposites while improving their biodegradation behavior. These outcomes allow for widening the application field of PLA biocomposites in those areas requiring a stiff and lightweight material with low deformability and faster biodegradability.

Alcoholysis of waste PLA-based plastics to methyl lactate over sulfated ZrO2/SiO2 catalyst

Polylactic acid (PLA) is popularly used to replace some petroleum-based polymers due to its biodegradability. However, biodegradation of waste PLA requires specific bacteria, stringent conditions and long time. Catalytic recycling of waste PLA to valuable added products rather than composting is a sustainable green routine. In this work, catalytic alcoholysis of waste PLA to methyl lactate (MLA) was carried out over a SiO2 @UiO-66 derived solid acid (SO2–4/ZrO2/SiO2). Characterizations indicated that SO2–4/ZrO2/SiO2 processed large surface area and homogenously dispersed acid sites, and it exhibited excellent performance for the alcoholysis of waste PLA under mild conditions. At 140 oC, the yield of MLA is 92.7% within 5 h, and SO2–4/ZrO2/SiO2 could be recycled at least five times without obvious loss of activity. The specific yield of MLA over SO2–4/ZrO2/SiO2 reached 2678 mg-MLA/g-cat/h, which was higher than that of H3PW12O40, Amberlyst-45, Hβ, HZSM-5 and α-ZrP. At the same time, SO2–4/ZrO2/SiO2 was also capable of the alcoholysis of waste PLA-based products. A possible pathway of PLA alcoholysis over SO2–4/ZrO2/SiO2 catalyst was proposed.

PLA Degradation and PLA-Degrading Bacteria: A Mini-Review

Polylactic acid (PLA) is not new to the world of science, since the application of PLA can be found in various industries such as biomedical, agricultural, and packaging. Despite the amazing properties shown by PLA, it still has a setback in terms of waste disposal of PLA. Since PLA is more resistant towards bacterial attack, it prolonged the decomposition of PLA disposed in the environment. Therefore, PLA microbial degradation and enzymatic degradation needs to be highlighted since most PLA waste will end up in the landfill. Most PLA-degrading can be found in the genus family Amycolatopsis, and a few can be found in the genus Lentzea, Kibdelosporangium, Paecilomyces, Thermomonospora, and Thermopolyspora. The enzymatic degradation of PLA is mostly studied relating to enzyme proteinase K, serine protease, and even hydrolase. This review paper aims to discuss the microbial degradation mechanism of PLA as well as the types of microorganisms and enzymes that involve in the biodegradation of PLA.