Investigation of laccase activities of microfungi isolated from different agricultural by-products and wastes

The aim of this study was to isolate microfungi from by-products and wastes obtained from agricultural products produced in Thrace, morphological and molecular identification of fungal isolates, qualitative and quantitative determination of laccase activities, extracellular laccase production by solid substrate fermentation (SSF), optimisation of production conditions and determination of some properties of laccase enzyme. Five isolates were identified as Aspergillus sydowii BSL 22, Cladosporium cladosporioides BSL 32, Cladosporium velox BSL 17, Fusarium proliferatum BSL 16 and Trichothecium roseum BSL 10. The isolate with the highest laccase activity was Fusarium proliferatum BSL 16 (19.42 ± 1.34 U/L), the isolate with the lowest activity was Aspergillus sydowii BSL 22 (5.28 ± 0.50 U/L), the substrate with the best activity was wheat bran (14.56 ± 0.80 U/L) and the substrate with the lowest activity was corn meal (4.87 ± 1.05 U/L). In the continuation of the study, laccase production was carried out in SSF medium prepared using F. proliferatum as the laccase source and wheat bran as the substrate and the production conditions were optimised. The highest laccase activities were measured in SSF media with initial moisture content of 60% (23.99 ± 1.45 U/L), pH value of 5.0 (25.96 ± 1.11 U/L), inoculum amount of 2.0 mL (18.21 ± 1.74 U/L) and on the seventh day of the incubation period (24.30 ± 1.53 U/L). In order to investigate some properties of the laccase enzyme obtained from F. proliferatum, maximum enzyme activities were recorded at pH 3.5 (32.26 ± 1.07 U/L), 40ºC (22.29 ± 1.86 U/L) and 3 minutes (33.84 ± 0.34 U/L) as a result of incubation of the reaction mixture at different pH, temperature and time. In conclusion, within the scope of this thesis study, a new fungal laccase source, F. proliferatum BSL 16 isolate was obtained from Thrace Region. Bran obtained from wheat, which is the most cultivated wheat in the region, was used as a substrate in the biotechnological production of laccase enzyme of industrial importance. In this study, environmentally friendly and economical fungal laccase production was carried out by SSF technique.