Experimental and in silico approaches to identify a sustainable source of bioplastics from seaweeds

Carrageenan was extracted from Kappaphycus alvarezii, alginate from Sargassum wightii, and agar from Gracilaria crassa and Gelidiella acerosa respectively. The plastic film formed with carrageenan, sodium alginate, and corn starch (F6) showed a higher tensile strength (TS) of 3.051 N/mm² followed by a TS value of 3.073 N/mm² for films made of carrageenan, sodium alginate, and agar (F7). The lowest tensile strength (0.984 N/mm²) was observed in agar film (F3). Garden soil led to higher biodegradation of the seaweed films compared to clay and beach soil. The films F6 and F7 biodegraded with a loss of 90 and 74% respectively within 30 days in garden soil. Given the better biodegradability and better TS and E value, the film F6 (carrageenan sodium alginate and corn starch) can be improvised for wider applications in food packaging and biomedical applications. FT-IR results of F6 bioplastics possessed characteristic peaks that support the chemical properties of bioplastics derived from seaweeds. The molecular docking and molecular dynamics simulation analysis showed that these three biopolymers maintained favorable binding and strong interaction with the cutinase (CutL1) enzyme which is widely reported for the biodegradable function in Aspergillus oryzae. SEM images of the F6 bioplastic show a heterogeneous structure with enhanced roughness.

Graphical abstract