Degradation of PLA-PBAT-Starch Blend Film by a Newly-Isolated Fungus Humicola sardiniae Strain S2-3 Under Ambient Temperature Condition

Abstract

Humicola sardiniae Strain S2-3 was isolated from PLA-PBAT-Starch blend film which was buried in vegetable patch for 2 months. For the isolation of the strain, bioplastic emulsified agar was used and the degrading ability was confirmed by observing clear-zone on bioplastic emulsified agar. In order to identification of the strain, ITS gene sequence and β-tubulin gene sequence were used and identified as Humicola sardiniae. Cell growth confirmation, clear zone forming confirmation on bioplastic emulsified agar, SEM analysis for confirmation of surface morphology change, UTM analysis for tensile strength evaluation, FT-IR analysis for confirmation of chemical linkage change, HPLC-MS analysis for identification of products from PLA-PBAT-Starch blend film as metabolites and HPLC analysis for confirmation of TPA degradation were performed for the evaluation of biodegradation of PLA-PBAT-Starch blend film by Humicola sardiniae Strain S2-3. The bioplastic film utilization by Humicola sardiniae Strain S2-3 was observed in basal broth media and agar plate including clear-zone forming around the colony. Utilization of corn-starch was observed by inoculation in 0.2% of corn-starch basal broth media. Utilization of PBAT was observed on PBAT emulsified agar, but not observed on PLA emulsified agar. Surface morphology change including erosions and cracks on the PLA-PBAT-Starch blend film was observed by using SEM analysis. Chemical linkage changes were identified between 3000~2840 cm-1 of wavelength by using FT-IR analysis. Extreme fragmentation was confirmed that it was too fragmented to measure by using UTM tensile test. Metabolites including terephthalic acid, adipic acid and polymers were observed and annotated by using HPLC-MS analysis. It was confirmed that terephthalic acid was not utilized by Humicola sardiniae Strain S2-3. Lipase secreted from Humicola sardiniae Strain S2-3 was evaluated to be positive.