Isolation of Marine-Derived Microorganisms for PET Biodegradation

Mangrove‑derived halophilic microbiome as a biocatalyst for polyethylene terephthalate (PET) microplastic breakdown.

Mangrove ecosystems are productive coastal habitats that provide important services, including shoreline stabilization, nutrient cycling, and nursery grounds for diverse marine species. Microplastics may represent a threat to many mangrove ecosystems. One of the most significant types of plastics is polyethylene terephthalate (PET), which is notable for its durability and potential to cause serious ecological damage. The use of halophilic and halotolerant microbes offers a promising approach for removing these pollutants in saline environments like mangroves. In this study, a halophilic and halotolerant consortium capable of PET degradation was isolated. This bacterial-fungal consortium, dominated by Methyloligella (32.54%), Truepera (12.25%), and Saccharomyces, showed PET degradation activity under 5% (w/v) NaCl conditions. It achieved a 15.5 ± 0.71% PET degradation efficiency within 50 days, accompanied by a maximum CO₂ concentration rate of 458 ppm. Physicochemical investigations, including Scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, and Thermal-gravimetric analysis (TGA), confirmed surface erosion, alterations in chemical bonds, and a higher rate of thermal degradation, respectively. Moreover, Gas chromatography-Mass spectrometry (GC-MS) exhibited the formation of alkanes as PET degradation products. Given the ecological importance of mangrove ecosystems and their increasing exposure to microplastic contamination, these findings demonstrate that this consortium shows potential for PET degradation and could serve as a viable option for bioremediation in saline ecosystems.

Enzymatic degradation of plastic and optimization of microbial system for the production of its degrading enzymes

This study outlines existing metabolic engineering techniques for bio-upcycling PET into high-value compounds, as well as a number of engineering approaches intended to improve the performance of PET-degrading enzymes. One of the most popular aromatic polyesters in the world, polyethylene terephthalate (PET) has an annual demand of over 29 million metric tons in 2022 and is expected to rise by 40% by 2030. Due to the growing amount of PET waste and the existing insufficiency of recycling techniques, it has accumulated in terrestrial ecosystems, posing serious hazards to world health. These technologies seek to convert recovered PET into more valuable items in order to address energy issues as well as environmental sustainability. One potentially biosustainable technique for handling and recycling plastics is enzyme-mediated biocatalytic depolymerization. Protein engineering developments have been applied to modify and improve the many plastic-degrading enzymes that have been discovered from microbial sources. Additionally, microbial metabolic engineering makes it possible to create customized microbial chassis that can break down PET substrates and transform the resulting monomers into compounds that are useful for industry.

Isolation and Characterization of Polyethylene-Degrading Bacteria from Municipal Dumpsite Soils of Gujarat, India

Plastic waste accumulation, particularly polyethylene, poses a significant environmental challenge due to its recalcitrant nature and persistence in ecosystems. The present study aimed to isolate, characterize, and evaluate polyethylene‑degrading bacteria from municipal dumpsite soils collected from Kalol (Gandhinagar) and Pirana (Ahmedabad), Gujarat, India. Soil samples were enriched in mineral salt medium (MSM) supplemented with polyethylene as the sole carbon source, followed by isolation and characterization of bacterial strains using morphological, biochemical, and molecular approaches. Two bacterial isolates were obtained and identified through Gram staining, biochemical profiling, and 16s rRNA gene sequencing as Bacillus paramycoides and Pseudomonas aeruginosa. Biochemical analysis revealed distinct metabolic capabilities, with Pseudomonas aeruginosa exhibiting stronger metabolic activities associated with polymer degradation. In weight‑loss assays, Bacillus paramycoides and Pseudomonas aeruginosa caused 3.59 ± 0.01 % and 4.85 ± 0.24 % mass loss of polyethylene films, respectively, after 90 days of incubation in MSM. FTIR analysis confirmed the appearance of new oxygen‑containing functional groups on the polymer surface after bacterial treatment, indicating oxidative degradation of polyethylene. These findings demonstrate that municipal dumpsite soils are valuable reservoirs of polyethylene‑degrading bacteria and highlight the potential application of Bacillus paramycoides and Pseudomonas aeruginosa in eco‑friendly plastic waste management strategies. Keywords: Isolation Characterization LDPE degrading bacteria 16s rRNA sequencing weight loss FTIR

Characterization of Biosurfactants Produced by a Novel Hydrocarbonoclastic Bacterial Strain Rhodococcus ruber N19 Isolated From River Sediment

Biosurfactants are eco‐friendly, surface‐active compounds produced by microorganisms that have significant industrial and environmental applications due to their biodegradability and low toxicity. This study focuses on the production and characterization of biosurfactants by bacterial strain N19, a novel hydrocarbonoclastic bacterium isolated from Soummam River sediment. The bacterium was cultured in mineral salt medium supplemented with crude oil to stimulate biosurfactant production. Surface tension reduction (23.14 ± 0.12 mN/m), emulsification index (72.13% ± 1.15%), and oil displacement (4.2 ± 0.75 cm) tests confirmed the presence of an effective biosurfactant. Further phenotypic and molecular identification methods, including 16S rRNA sequencing, established the strain's identity as Rhodococcus ruber N19. This strain produced 7.92 ± 0.02 mg/mL biosurfactant. Structural characterization using thin layer chromatography (TLC), Fourier‐transform infrared (FTIR) spectroscopy, matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry (MALDI‐TOF/MS), and liquid chromatography–tandem mass spectrometry (LC–MS/MS), and nuclear magnetic resonance (NMR) analyses revealed that the biosurfactant produced by this strain is a lipopeptide. The nonhemolytic properties, combined with the ability to lower surface tension and exhibit strong emulsification and oil displacement activities, highlight the potential of this biosurfactant for bioremediation, petroleum industry applications, and biomedical use.

Inducing Effect of Biosurfactants from Pseudomonas putida 12os Strain on Biodegradation of Hydrocarbons in Oil-Contaminated Soil

Metagenomic insights into potential PET hydrolases from Antarctic soils and rhizospheres

A metagenomic analysis of soil and rhizosphere samples from the Antarctic vascular plants Deschampsia antarctica and Colobanthus quitensis is conducted, as sources of microbial enzymes with potential PET-hydrolytic activity, demonstrating the diversity of PET-hydrolase-like genes within Antarctic rhizosphere and soil microbiomes.