Biodegradation of HDPE by Desert Bacteria: Insights from Isolates of the Lut-Desert, the Hottest Place on Earth

Abstract The environmental impact of plastic pollution, specifically from high-density polyethylene (HDPE), is significant due to its resistance to degradation. In this study, bacteria isolated from the Lut Desert, one of the hottest places on Earth, were investigated for their potential to degrade HDPE. Beta-hemolytic strains were prioritized due to their association with extracellular enzyme production and biosurfactant activity, which enhances surface adhesion and biodegradation. According to the BATH assay, 10 strains showed high hydrophobicity (34.44–37.38%), which improved bacterial attachment to polyethylene surfaces. HDPE degradation was evaluated through weight loss over 60 days, with values ranging from 5–14%. Strains 48, 44, 8 and 50 demonstrated the highest degradation efficiency, reducing HDPE the weight by 14.15%, 12.99%, and 12.01%, respectively. Gas chromatography-mass spectrometry (GC-MS) analysis confirmed that polyethylene biodegrades by producing alkanes, carboxylic acids, and alcohols as byproducts. The identification of laccase (cotA), alkane monooxygenase (alkB), and phosphatase (phoD) genes was confirmed through PCR amplification, which revealed the enzymes that regulate HDPE degradation. The combination of hydrophobicity, biosurfactant production, and enzyme activity underscores the potential of extremophilic bacteria as effective tools for polyethylene bioremediation. This study's findings provide valuable insights into plastic degradation caused by microbial activity, which provides promising solutions for managing plastic waste in extreme environmental conditions.