Pure-culture and enzymatic assay for starch-polyethylene degradable plastic biodegradation withStreptomyces species

A review of biodegradation of synthetic plastic and foams

“…The differing views have been attributed to several factors such as (1) lack of standardization in test methods (29), (2) different time scales adopted by different researchers in their test protocols (30), (3) PE's extremely slow process of biodegradation (31), (4) lack of a general consensus among researchers on a universal definition of PE biodegradation, (5) use of several modified forms of PE blended with additives such as starch (32), wood powders (33), and chromophores (34), etc. that are treated using several techniques such as heat (35) and ultraviolet irradiation (31,36) prior to subjecting PE to biodegradation, (6) lack of overall agreement among researchers on what biodegradation end products would make PE a biodegradable (37) polymer, (7) scarce information relating to enzymatic biodegradation (22,38), and no knowledge on genes encoding any specific enzyme that would biodegrade PE (39), and (8) lack of any definitive PE biodegradation mechanism (39). It is out of the scope of this paper to elaborate much on these factors.…”

Microbiological Degradation of Polymeric Materials

“…Other studies emphasize marine environments [86][87][88][89], natural soils [90,91], and river water [86,92,93]. In addition, enzymatic assays have been used to assess degradability of a specific polymer under laboratory conditions [86,[94][95][96] or to detect specific enzyme activity indicative of a degradative process, for example, esterases [12,[97][98][99][100][101][102][103][104][105][106][107][108][109][110][111][112]. Experiments in situ always suffer from poor reproducibility because of the broad range of variables involved [83,84] and the difficulty in interpretation of experimental results and extrapolation of possible mechanisms involved.…”

“…Aerobic conditions are often used to assess polymer biodegradation in many tests; examples are aerobic soil exposure [121,122], thermophilic composting [42,44,123], immersion in surface seawater [88,89,122] and freshwater [86,93], and laboratory batch conditions [92,95,96,[124][125][126]. In addition, the enclosed living environment not only harbors a range of microorganisms; the microorganisms are detrimental to both human health and material integrity [6,[127][128][129][130][131][132][133][134][135][136][137][138].…”

“…Degradation rates may be increased by 2-4% following photosensitizer addition. In one study, extracellular culture concentrates of three Streptomyces species were inoculated to starch containing PE films [95,96], and PE was claimed to be degraded. Degradation of PE by microorganisms may be minimal without taking into account physical and chemical processes, and the data on degradation of PE-containing starch are Visual evaluation [208] MIL-STD-810E Method 508.4…”

Evaluation for food packaging potential and environmental compatibility of novel degradable starch-polyethylene plastics

“…Pure-culture method (51,64) Chemically disinfected films are transferred into sterile culture medium and inoculated with test microorganisms.…”