Growth and Phytohormones Production by Thermophilic Aspergillus fumigatus 2 and Thermotolerant Aspergillus terreus 8 Strains in Salt Stress

Abstract

Few investigations have been made the biodiversity and biological properties of fungi in natural high salt and thermal environments. Halophilic and thermophilic fungi belong to extremophiles, which can survive in salt-affected habitats. Thermophilic and thermotolerant fungi are little known for indole-3-acetic (IAA) and gibberellins (GAs) production and their growth, development in salt-affected (salt-stress) environments. Aim of the current studies was to investigate the IAA and GAs synthesis by the thermophilic A. fumigatus 2 and thermotolerant A. terreus 8 strains, and their behavior in salt-stress. These fungal strains exhibited maximum IAA and GAs production and growth under different salt (NaCl and Na2SO4) concentrations. Furthermore, the fungal strains were able to synthesize the phytohormones in elevated temperatures – Aspergillus fumigatus 2 in 55ºC, Aspergillus terreus 8 in 45ºC. Salt tolerance estimations showed that Aspergillus terreus 8 was salt tolerant and exhibited ability to produce the phytohormones in the presence of salts. This is a first report on the isolation and description of thermophilic and thermotolerant Aspergillus, which synthesize IAA and GAs in the presence of NaCl and Na2SO4. In relatively low salt concentrations A. terreus 8 synthesized the phytohormones nearly as the same as in the control, but in presence of 0.5-1% salts, the synthesis of both metabolites sharply reduced, first of all, the production of GAs.