Endolithic fungi from deep sea calcareous substrata: isolation and laboratory studies

Fungi were isolated from calcareous animal shells at 100-860 m depth in the Bay of Bengal. All the species isolated were terrestrial ones, Aspergillus restrictus Smith being the most common. The behaviour of this fungus at various hydrostatic pressures was examined. Conidia germinated on Czapek-Dox medium with 3 and 20% sucrose and on shells in seawater at hydrostatic pressures up to 300 atm., the percentage of germination being highest in CDA medium with 20% sucrose than in normal CDA and on shells. Conidia of an isolate of Aspergillus niger van Tieghem, obtained from intertidal calcareous shells, on the other hand, did not germinate above 1 atm. Upto 512 Mu calcium was leached out upon growth of A. restrictus on 1 g of calcareous shell substrata at 100 atm. in 25 days. This fungus was not capable of acid production on nutrient media in the presence of various carbon sources, nor did it produce proteases. The role of fungi in calcareous substrata in the sea is discussed with reference to our findings.