Fresenius Environmental Bulletin, vol.26, no.11, pp.6525-6531, 2017 (SCI-Expanded)
Extremophile microorganisms can survive in
many different environments such as high salt concentrations, high temperatures, high pressures and extreme pHs. They generate unique industrial biocatalysts, run in the extreme conditions. Similarly, Alcohol Dehydrogenases (ADH) from halophilic/halotolerant fungi are exciting biocatalysts with potential industrial applications. In this study, the microfungi isolated from Lake Tuz (Salt Lake or Tuz Golu) in Turkey were investigated in terms of ADH enzyme activity. Primarily, 38 fungal isolates were screened for ADH enzyme activity and then eight isolates with the highest activity were identified by molecular methods with sequencing of internal transcribe spacer regions. These species are the following; Cladosporium macrocarpum, Eurotium niveoglacum, Aspergillus versicolor, A. niger, C. sphaerospermum, C. cladosporioides, Penicillium chrysogenum and E. amstelodami. Specific enzyme activity of these species ranged from 3.21 to 5.93 U/mg.
For purification of the enzyme, ammonium sulfate precipitation and dialysis methods was applied to extract of A. niger. SDS-PAGE and HPLC method was used to indicate the presence of proteins and protein profiles in the dialyzed extract. The activity of A. niger ADH was investigated in high salt concentration conditions. In salt stress, the specific activity increased by 4.2%. Consequently, ADH of A. niger is biotechnologically important because it is an active enzyme in extreme conditions.