Table 7.
Biodegradation of MPs.
| MPs-degrading bacteria | Source | Degradation mechanism | Types of MPs | Degradation efficiency | Reference |
|---|---|---|---|---|---|
| Rhodococcus sp. and Bacillus sp. | Mangrove sediment | The two bacterial isolates possibly possessed the enzymatic components needed to degrade PP | Isotactic PP−MPs granules (white, spherical) with a density of 0.9 g ml−1 at 25 °C, molecular weight of 250,000 Mw, average Mn of 67,000 | The weight loss of PP after 40 days: Rhodococcus sp. 4.0% and Bacillus sp. 6.4% | [156] |
| B. cereus and B. gottheilii | Mangrove sediment | The bacterial isolates possess functional groups that can attach to the microplastic surfaces | PE powder (white/75 μm, 0.94 g mL−1), PP granules (white/spherical, 0.9 g mL−1), PS granules (white/spherical, 1.59 g mL−1), PET granules (granular/milky white, 1.68 g mL−1) | After 40 days, the percentage weight loss of PE, PET, and PS by B. cereus was 1.6%, 6.6%, and 7.4%, respectively; the percentage weight loss of PE, PET, PP, and PS by B. gottheilii was 6.6%, 3.0%, 3.6%, and 5.8%, respectively | [157] |
| Zalerion maritimum | Maritime coastal waters | Zalerion maritimum used PE-MPs as a nutrient source | PE−MPs (250–1000 μm) | The weight loss of PE−MPs in 14 days was 56.7 ± 2.9% | [158] |
| Pure bacterial strains, Bacillus licheniformis and Lysinibacillus massiliensis, and a mixed bacterial Culture of Delftia acidovorans and Bacillus sp. | Activated sludge and sediment | There was a release of additives from the surface of LDPE−MPs and PS−MPs and disruption of its structure |
LDPE, PS−MPs (300–500 μm) | N/A | [159] |
| Aspergillus flavus named PEDX3 | The guts of wax moth Galleria mellonella | Two LMCOs that isolated from Aspergillus flavus were considered as the potential PE-degrading enzymes after preliminary screen | LDPE with density of 0.921 g cm−3, HDPE with density of 0.955 g cm−3 (＜200 μm) | The mass loss percentage (Δm/m0) was 3.9025 ± 1.18% after 28 days | [161] |
| Greater wax moth (Galleria mellonella) larvae | N/A | Through the styrene oxide–phenylacetaldehyde, and 4-methylphenol–4-hydroxybenzaldehyde–4-hydroxybenzoate metabolic pathways | PS microbead suspensions with and without red fluorescence labeling (25 μm, provided as mono-spheres suspended in distilled water at a concentration of 2.5% w/v) | 27%, 56%, 66%, and 80%, respectively after 3, 6, 12, and 18 h | [162] |
| Activated sludge and the compost cell suspension | Activated sludge | Hyperthermo-philic composting (hTC) technology | Extracted from activated sludge (<0.5 mm) | 43.7% of the MPs was removed from the sewage sludge after 45 d; the hTC in-oculum degraded 7.3% of the PS−MPs at 70 °C in 56 days in lab-scale | [109] |
| Bacterial communities in activated sludge | Activated sludge | Two bacterial strains within the consortium were isolated and identified as B. cereus SEHD031MH and A. mediolanus PNP3 demonstrated a great potential to degrade PET | Polycaprolactone diol (PCL) (Mn 2000) and PET−MPs (>40% crystallinity and inherent viscosity 0.80 dL g−1) (300–425 μm) | The consortium degraded 17% of PET and 34% of PCL (at 30 °C, pH 7–7.5, reactor residence time 168 days, and PET concentration of 2.63 g L−1) | [108] |
| Mixed microbial consortium | Landfill site | A mixed bacterial culture mainly consisting of Bacillus sp. and Paenibacillus sp. isolated from a landfill site could help accelerate PE−MPs degradation | PE−MPs granules (white and amorphous) with a density of 0.94 g mL−1 at 25 °C | The weight loss of PE microplastic was 14.7% after 60 d | [160] |
| Bacterial community on microplastics | Urban river sediments | The plastic-degrading bacteria were the crucial factor for the degradation of MPs and the deeper sediment conditions may promote the biodegradation of MPs | Extracted from urban river sediments (<1, 1–2, 2–3, 3–4, 4–5, and >5 mm) | N/A | [164] |
| Periphytic biofilm in various backgrounds of carbon sources (glucose, peptone, and glucose and peptone) | Xuan Wu Lake, Nanjing, to obtain a natural microbial entity of complex structure | Adding and/or changing a C-source changes the density and diversity of periphytic biofilms and influences the biodegradation of MPs by periphytic biofilms | PP, PE, PET−MPs (dimensions <1000 μm) | 9.52–18.02%, 5.95–14.02%, and 13.24–19.72% for PP, PE, and PET respectively, after 60 d | [165] |
| Human colonic microbiota | Human colonic | Gastrointestinal digestion and colonic fermentation | PET−MPs (160 ± 110 μm) | N/A | [167] |