Conidial germination of marine-derived fungi under simulated deep-sea conditions in the presence of inducers

Abstract

The abilities of conidia of four deep-sea fungi, Aspergillus flavus NIOCC20, A. sydowii CH2, A. terreus A4636 and Penicillium sp. A4623 and one terrestrial fungus, A. terreus MTCC479 to germinate under simulated deep-sea conditions were investigated by exposing the conidia to low temperature (4 °C) and elevated hydrostatic pressures (10, 20, 30, 40, 50 and 60 MPa). The conidial germination was evaluated in presence of chemical inducers, including Thiamine, Sodium pyruvate, Hydrochloric acid, Sulphuric acid and Sucrose, in a basal medium of 1/5th strength of malt extract broth and subjected to heat treatment at 70 °C for 60 min, and incubated for 30 days under simulated deep-sea conditions. The conidia of Aspergillus flavus, A. sydowii and Penicillium sp. germinated and developed into mycelia under almost all the treatments with and without heat inducement. However, the number of germinated conidia of A. terreus A4636 and A. terreus MTCC479 was lower than the other three fungal species. This is the first study demonstrating in vitro germination of conidia of deep-sea fungi at low temperature with elevated hydrostatic pressures. Further studies are warranted to obtain insights into in situ conditions that are favourable for conidial germination and fungal activity in deep-sea niches.