Table 2 Degradation Information for natural polymers and natural materials
From: What can we learn from biodegradation of natural polymers for regulation?
Natural polymer | General aspects | Degradation result | Summary | References |
|---|---|---|---|---|
Cellulose | Recommended reference substance for ISO tests (validity criterion > 60% in 6 month, results usually higher) | Data for different compartments (water, seawater, soil, activated sludge) available Soil: Plateau at about 70% mineralization or higher | Relative fast degrading; (see general aspects) | Martin and Haider [58], Kögel-Knabner [25], Gómez and Michel [59], Chinaglia et al. [60], Pischedda et al. [61], Tosin et al. [62], Briassoulis et al. [63], Tyagi et al. [33] |
Starch | Degradation rates may be dependent on concentration; decreasing up to 50% when the starch present is < 10% of the soil organic matter (SOM) Low starch concentrations, in combination with low activity of starch degrading organisms could lead to stabilisation of starch in the SOM fraction | Disappeared (only partly mineralized) within 35 days in soil after incubation Other studies show high mineralization (> 80%) in 12 weeks Large fraction already degrades in soil within 3 days, but can take several weeks to year to be degraded entirely | Highly degradable Biodegradation rate faster than for cellulose Biodegradation asymptotic | Cheshire et al. [64], Martin and Haider [58], Kögel-Knabner [25], German et al. [65], Polman et al. [24], Tyagi et al. [33] |
Hemicellulose | Easily hydrolysable polymers | Aqueous medium (ISO 14851):  > 80% in 10 days | Degradable | Dekker [66], Pérez et al. [67], Erdal and Hakkarainen [68] |
Lignin | Lignin turnover in soils could be faster than that of the total SOM Degradation is related to the nature of vegetation and land-use, but also to the climate and soil characteristics Co-metabolism with easily degradable carbon sources (sufficient energy, nutrients, enzymes) Fungi such as basidiomycetes and white-rot fungi are the only organisms able to extensively biodegrade lignin | Laboratory: 19–60% degradation for 13 weeks to 2 years Field studies; degradation up to 5 years Other literature reported that lignin degradation takes years or decades | Slower degradation rates in comparison to cellulose or starch Incorporation into SOM Complex structure of lignin makes it recalcitrant to most degradation processes | Kögel-Knabner [25], Thevenot et al. [57], Datta et al. [32], Polman et al. [24], Tyagi et al. [33], Amelung et al. [48] |
Cutin | Cutin is an extracellular polymer Enzymatic hydrolysis (cutinase) as an important pathway | Many microorganisms can grow on cutin as their sole carbon source and produce extracellular cutin hydrolyzing enzymes Fully hydrolyzed by soil microorganisms in a period of 3–8 months |  | Kolattukudy [69], Heredia-Guerrero et al. [70] |
Natural rubber | Degradation of natural rubber is a slow process Various bacteria are reported to be able to degrade natural rubber Most likely microbial attack targets the double bond of the cis-1,4-polyisoprene chain (oxidation) | Degradation is proven in experiments with isolated bacterial cultures. However, no standard degradation tests are available in literature |  | Rose and Steinbüchel [36], Nguyen et al. [71], Joseph et al. [72], Berekaa et al. [73], Shah et al. [39], Borel et al. [74], Nanthini and Sudesh [75], Kasai et al. [76], Seidel et al. [77], Shah et al. [78] |