Role of Hydrolytic Enzymes of Some Fungi in Rotting Fruits and a Possibility of Retard Spoilage

This study was designed to identify some fungi responsible for damage of fruits in storage and sale outlet markets. Results declared the role of CMC-ase and poly galacturonase (PG) enzymes secreted by three fungi of Alternaria alternata, Penicillium italicum and Rhizopus stolonifer in decomposition of tomato, lemon and cucumber fruits at the grocery markets in Sakaka, Saudi Arabia. CMC-ase and PG were produced after 2 days for P. italicum, R. stolonifer whereas very little quantity was detected for A. alternata. Maximum CMC-ase and PG production were seen after 8-10 days of incubation at 28oC. Enzyme production started at a temperature of 5°C but in small quantities, then the production began to increase steadily until the temperature of 28°C, which produced the highest amount of enzymes. The production began to decline starting at 35oC to be at the lowest rates at 40oC. Enzymes were produced at pH values of 4.5-9.5, with optima between 5.5-6.5 for the three tested fungi. Acidic medium of pH 4.5, and alkaline medium (above pH 6.5) affected negatively on the production of enzymes, and this effect was more evident in the exo CMC-ase and exo PG than in endo enzymes. Results showed that the mixture of menthol crystals & Eucalyptus oil & camphor & methyl salicylate oil-rich air inhibited growth of R. stolonifer and A. alternata by 100% and inhibited the growth of P. italicum by approximately 50%, compared to the control sample. Camphor and mint oils gave negative effect. Application of devices to emit the odor and quench this mixture of menthol crystals & Eucalyptus oil & camphor & methyl salicylate to fumigate the air of stores and outlets for selling vegetables and fruits are recommended.