Barotolerance of fungi isolated from deep-sea sediments of the Indian Ocean

Two species of filamentous fungi, Aspergillus ustus (Bain.) Them & Church and Graphium sp., were isolated from calcareous animal shells at depths of 860 m in the Arabian Sea and 965 m in the Bay of Bengal. Laboratory experiments showed germination of conidia, growth of hyphae and microconidiation in both the fungi at 100 bar pressure at 10 and 30 degrees C, suggesting barotolerance. The fungi also secreted barotolerant protease under these conditions. Protease synthesised and secreted in cultures grown at 1 bar was also active under 100 bar pressure at 10 and 30 degrees C. At 10 degrees C, the fungi showed better conidial germination, growth and protease secretion when subjected to 100 bar than when grown at 1 atmosphere. The results indicate barotolerance of terrestrial species of fungi and suggest that they might be active under deep-sea conditions.