Determination of xylanase production capacities of marine-derived filamentous fungal strains

In general, several industrial enzymes are derived from terrestrial organisms. However, Oceans, covering 70% of the earth surface, include salinity, high pressure, low temperature and special lighting conditions contribute to the differences between enzymes produced by marine microorganisms and homologous enzymes from terrestrial microorganisms. When compared with the terrestrial environment, marine environment gives marine microorganisms unique genetic structure and life habitats. Therefore, obtaining enzymes that can be used in biotechnology from fungal samples adapted to marine conditions is of a great importance. In this study, marine-derived fungal isolates from different sponges and sediments samples from the Aeagean and the Mediterranean Region were screened in terms of xylanase production. In total, it was determined that 81 (75%) out of 108 isolates exhibited xylanase activity in an agar plate assay. As a result of screening, protein concentrations, enzyme activities and specific activities of four isolates showed the highest xylanase activity (06SK019, 08SK014, 08ÇK001 and 08SK016) were calculated and isolate with the highest xylanase activity was identified as Trichoderma pleuroticola 08ÇK001. Fermentation of 08ÇK001 was completed, with a working volume of 1250 ml, and partial purification of enzyme by ammonium sulphate precipitation was realized. Afer dialyses, xyalanse was purified 2.3-fold with a recovery of %40.3 and its specific activity was up to 1195.5 U/mg. Optimum temperature and pH values of enzyme were determined as 50°C and 5.0, respectively. Enzyme showed stability at pH 5.0 and 4°C temperature by retaining %53 of initial activity after an hour incubation, and it was retained its activity %18.1 at the end of 15 minutes. It was found that the activity of enzyme was stimulated by K+, Ba2+, Na+, β-mercaptoethanol, Triton X-100 and toluene, but was inhibited Fe2+, Ca2+, Co2+, Mn2+, PMFS, hexane, ethanol and isoamyl alcohol. In this study, xylanase from marine-derived fungus isolate Trichoderma pleuroticola 08ÇK001 was partially purified and characterized, because of its optimal pH and temperature values as well as its resistance to inhibitors and metal ions tested, it is thought that enzyme has a potantial for being used in food and animal feed indusrty.