Synergistic plastic degradation by Pseudomonas putida and Klebsiella pneumoniae: Exploring bacterial potential for biodegradation

Plastic pollution has become a significant global threat to the environment, especially in the Philippines. Conventional waste management methods, such as incineration and landfilling, contribute to environmental harm, prompting interest in microbial biodegradation as a sustainable alternative. This study aimed to address the challenges in the slow degradation of plastics by using the combination of Pseudomonas putida and Klebsiella pneumoniae for enhanced polyethylene terephthalate (PET) degradation. Specifically, the study examined the co-culture growth of P. putida and K. pneumoniae, evaluated their synergistic plastic degradation through measuring the optical density, and analyzed the effect of varying pH (6.5, 7.0, 7.5) and temperature (30°C, 37°C, 45°C) on the degradation process. Optical density (OD) readings were obtained using a spectrophotometer to monitor bacterial growth, while weight loss measurements were used to confirm and quantify PET degradation. The co-culture demonstrated the highest OD values on Day 3 (0.676) and Day 7 (0.613), indicating enhanced growth through metabolic synergy. The highest degradation rate of 0.52% was observed at pH 7.0 and 30°C in the mixed culture. ANOVA results revealed no significant effect of pH (F = 1.049, p = 0.362) or temperature (F = 0.436, p = 0.650) on degradation. However, statistical significance in PET degradation was observed only in the co-culture (p = 0.014). This study reveals that P. putida and K. pneumoniae can co-exist with enhanced microbial growth when grown in the nutrient broth. Varying pH and temperature have no effect on the degradation rates of PET plastic. The mixed culture of P. putida and K. pneumoniae exhibited statistically significant growth, thermal tolerance, and synergistic plastic degradation.