Cutin from watermelon peels: A novel inducer for cutinase production and its physicochemical characterization

Cutin a polymeric biological macromolecule made up of esterified polyacids which acts as an inducer of cutinase. The present work was based on screening and characterization of newer cutin source from the agro industrial wastes as inducers of cutinase production by Fusarium oxysporum MTCC 2480. Cutin isolated from peels of multi green colored watermelon (WMC) yielded 6.77 U/mL as compared to that 9.64 U/mL of cutinase using apple cutin. The FTIR and 13C CP-MAS solid state NMR studies indicated the nature of WMC to be an aliphatic polyester of polyhydroxy fatty acids. A further FTIR spectroscopic study on dewaxed cutin confirmed that the ester linkages in WMC were completely hydrolyzed during submerged fermentation. GC-MS data clearly indicated the critical structural feature of WMC viz. hydroxyl groups at ω-position and middle of the fatty acid chain. The amorphous nature of WMC was confirmed by XRD. DSC of WMC showed two endothermic transition peaks, one broad appearing at 30-60 °C and other at 145 °C. Thermogravimetric analysis of WMC suggested it to be thermally stable up to 200 °C. This study warrants further work on using WMC as a substrate for fermentative production of cutinase.