I am conducting research to find bacteria capable of degrading plastics. I have found several methods, but most are qualitative. I would like to know if anyone has used any quantitative method that is easy to implement and low-cost?
1. Weigh plastic samples before & after exposure to bacterial cultures for a set period. The difference in weight can indicate the extent of degradation.Use a sensitive balance and prepare controls to ensure accurate results.
2. Use colorimetric assays to measure the release of byproducts from plastic degradation. For example, measure changes in absorbance using UV-Vis spectrophotometry to assess the concentration of degradation products.Use inexpensive reagents for color development.
3. Stain plastic surfaces with fluorescent dyes that bind to biodegradation products and analyze them under a fluorescence microscope.
4. Analyze gaseous byproducts from the bacterial degradation process using gas chromatography, which can quantify compounds released during plastic degradation.
5. Measure the BOD of the culture medium before & after exposure to degradation processes, as increased microbial activity due to plastic degradation may reflect in higher BOD values.
6. Monitor changes in pH of the medium over time due to metabolic activity of the bacteria breaking down plastic.
7. Measure the optical density (OD) of bacterial cultures grown on plastic compared to a control. An increase in OD may indicate plastic degradation.
8. Use Fourier-transform infrared spectroscopy (FTIR) to quantify changes in the chemical structure of plastics after bacterial treatment.
What "plastic"?
Plastic in commerce, esp. as packaging, includes 20-50% fillers and plasticizers. Readily degraded, these lead to disintegration of the material with little to no change in the plastic polymer itself. The result is apparent "degradation" of plastic with no real impact on the target polymer.
Weight Loss Measurement: To determine the rates of degradation, weigh plastic samples both before and after they are exposed to bacteria. CO₂ Evolution Test: Use basic respirometric equipment to track the amount of CO₂ generated by bacterial respiration as a gauge of polymeric carbon mineralisation. Surface Area Change: To monitor bacterial activity-induced changes in the plastic's surface area, pits, or cracks, use image analysis or microscopy. FTIR Spectroscopy: After bacterial treatment, use Fourier-transform infrared (FTIR) spectroscopy to identify chemical changes in plastic polymers. Turbidity Measurement: Using plastic samples, track variations in turbidity to gauge bacterial growth (which is indirectly linked to deterioration) in liquid conditions.
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