Effects of gamma radiation on enzymatic production of lignolytic complex by filamentous fungi

Abstract

This work aimed to study the effect of gamma radiation on the production of enzymes by filamentous fungi present in the seawater used for thermoelectric Termope S / A, in the vicinity of Port of Suape, Pernambuco. The isolated microorganisms were screened for their ability to produce enzymes. Subsequently, the fungi were irradiated at 3 doses (500, 1000 and 1500 Gy), using 4 inoculation techniques: lyophilisation, scraping of the spores, glass beads and agarose block. A fermentation assay for enzyme production was made in simple batch using a bioreactor New Brunswick, model Bioflo 110. The best enzyme produced was lignin peroxidase (676 U/L) by Aspergillus awamori in 500 Gy dose. Manganese peroxidase enzyme (1720 U / L), produced by three species of fungi (Penicillium sp.), was the highest in 500 Gy dose. Aspergillus terreus produced laccase enzyme (980 U/L) better in 500 Gy dose. In the assay of the fermentation bioreactor, the best results were found in BH-amid corn steep liquor, where 650 U/L of laccase was produced at the baseline and also in the medium containing corn steep liquor, where 620 U/L laccase was produced during 72 h. This is better than Sabouraud. The use of gamma radiation increased the production of enzymes by filamentous fungi compared to tests without radiation. Statistical analysis shows there are no significant differences between the inoculation techniques, and the best dose of radiation tested was 500 Gy. In trial bioreactor containing Bushnell Haas + corn steep, Penicillium sp. produced larger amounts of phenoloxidases enzymes compared to Sabouraud medium. Irradiation in a dose of 500 Gy stimulates A. awamori, A. terreus and Penicillium sp. to produce phenoloxidases enzymes.

Key words: Aspergillus, penicillium, corn steep, radiation.