Polyvinyl chloride biodegradation by Pseudomonas citronellolis and Bacillus flexus

Area of Science:

• Environmental Microbiology
• Polymer Science
• Bioremediation

Background:

• Petroleum-derived plastics, like polyvinyl chloride (PVC), pose significant environmental and health risks due to their persistence.
• Developing effective biodegradation strategies for plastics is crucial for mitigating pollution.

Purpose of the Study:

• To investigate the biodegradative potential of five bacterial strains (Pseudomonas chlororaphis, Pseudomonas citronellolis, Bacillus subtilis, Bacillus flexus, and Chelatococcus daeguensis) on various plastic films.
• To identify specific bacterial strains capable of degrading PVC films under aerobic conditions.

Main Methods:

• Initial screening of bacterial strains for plastic film degradation.
• Biofilm formation assays and Fourier-transform infrared spectroscopy (FTIR) analysis on PVC films.
• Biodegradation assays using PVC films incubated with selected bacterial strains (P. citronellolis and B. flexus) in flasks.
• Analysis of molecular weight changes using gel permeation chromatography (GPC).
• Gravimetric weight loss measurements on waste PVC films after incubation.

Main Results:

• Pseudomonas citronellolis and Bacillus flexus were identified as promising PVC film degraders.
• Both strains formed biofilms on PVC surfaces and induced modifications in FTIR spectra.
• Incubation with P. citronellolis led to a 10% reduction in PVC average molecular weight.
• Biodegradation assays on waste PVC films showed a gravimetric weight loss of up to 19% after 30 days.
• Bacterial activity primarily targeted PVC additives rather than the PVC polymer backbone.

Conclusions:

• Pseudomonas citronellolis and Bacillus flexus demonstrate the ability to biodegrade PVC films.
• The identified bacterial strains show potential for bioremediation of PVC plastic waste.
• Further research is needed to enhance the biodegradation rate of the PVC polymer itself.