Biotechnology Center Of Ho Chi Minh City

(SHTP) – From soil and plastic waste samples collected at several polluted sites in Ho Chi Minh City, the research team from the Environmental Biotechnology Department, Biotechnology Center of Ho Chi Minh City, isolated and selected indigenous bacterial strains capable of acting on polyethylene (PE), polyethylene terephthalate (PET), and polystyrene (PS). After 30 days of testing, several strains produced marked mass loss relative to the controls and induced changes in plastic surfaces observed by FE-SEM. The findings provide a potential microbial resource for developing biological solutions for plastic waste treatment.

From indigenous bacterial resources to the selection of promising strains

PE, PET, and PS are widely used polymers but are highly resistant to environmental degradation. The study explored microbial communities adapted to plastic waste at the Nhieu Loc–Thi Nghe Canal, Doi–Te Canal, Vam Thuat River, and Xuyen Tam Canal. Microorganisms were enriched in mineral salt medium containing PE, PET, or PS as a carbon source, and eight isolates—PE1, PE2, PET1, PET2, PS1, PS2, PS3, and PS4—were subsequently obtained. Their effects on plastics were evaluated based on mass changes after 30 days, FE-SEM imaging, extracellular enzyme activities, 16S rRNA identification, and PCR screening of selected genes associated with polymer metabolism.
  Effects of Selected Bacterial Strains on PE, PET, and PS

Five strains—PE2, PET1, PET2, PS1, and PS2—were selected for further analysis. PE showed the clearest response: PET1, PET2, PS1, and PS2 each exhibited apparent mass losses above 50%, corresponding to net mass losses of approximately 50.31–53.31% after control correction; PE2 reached 42.23%. For PET, PS2 showed the highest net mass loss at approximately 26.46%, followed by PE2 (17.40%) and PS1 (16.16%). PS was more resistant, with PS1 showing a net mass loss of approximately 11.20%.
 
Figure 2. FE-SEM images of PS, PET, and PE surfaces after 30 days. A, C, E: abiotic controls; B, D, F: samples incubated with the microbial consortium, showing surface pits, microcracks, and delamination.

Bacterial identification and markers associated with polymer metabolism

16S rRNA analysis assigned the selected isolates to the genera Streptomyces, Cupriavidus, Pseudomonas, and Aquipseudomonas; PS1 was identified as Pseudomonas lalkuanensis (99.24%), while the remaining isolates were retained at the genus level.
 

Environmental Biotechnology Department
 Biotechnology Center of Ho Chi Minh City