Study On Whole Cell Biocatalyst Of Alkaline PET Treating Bacteria

The industrial biotechnology, which takes biocatalysis as the main content, has become an important direction of biotechnology development. It begins to play an increasingly important role in material processing and product preparation. Currently, biocatalysis has extended to the polymer substrate as biotransformation from traditional small molecule as a research substrate. Bioprocess based on biocatalysis has started to become an important approach for polymers to achieve multifunctional and high performance. Polyethylene terephthalate (PET) is recognized as difficult biodegradable polymers, and it is a difficult problem to solve bioprocessing of PET material for a long time.The paper started with PET decomposing bacteria which can be grown with PET as a sole carbon source. The bioprocess of formation and utilization of PET biodegradable products under whole-cell biocatalysis was studied. The affect between particle size structure and biodegradable performance was analyzed with PET ultrafine particles. The evolutionary engineering was applied to screen alkali-resistant bacteria to decompose PET.Unlike enzymes, the intermediates were multi-species under the condition of decomposing PET. The interaction between strain, extracellular enzymes and substrates resulted in showing a wavy change both biomass and product concentrations. This paper found that whole-cell biocatalysis avoid inhibition for that intermediate product containing ester block enzymes treatment process. Experimental results show that PET pellets did not change its crystalline microstructure in whole-cell bioprocess. but it can improve the crystallinity of the PET surface.Strain was culturing with different diameter PET particles as the sole carbon source. The effect of different particle size of PET applied as substrate on the growth of strain was investigated. The results showed that the growth rate and biomass of strains were much greater than the larger when the smaller PET powder as a substrate. After long-term treatment, the crystallinity of smaller particles increased obviously and size distribution was in a narrow range. PET diameter reduced due to the interaction of enzyme molecules on the surface of the substrate.Alkali-resistant strains capable of decomposing PET was obtained through the method of evolutionary engineering. The initial strain was Comamonas testosterone F4 laboratory screened. Evolutionary strain was able to grow at a pH of 12 culture conditions. PET film has obvious signs of etching with alkali-resistant strains, and the surface elements changes simultaneously.