Effects of Hypobaric and Hyperbaric Pressures on Mycelial Growth of Isolated Strain of Wild <i>Ophiocordyceps sinensis</i>

Abstract

The exploration of the effects of pressure leads to new insights into the mycelial growth of Paecilomyces hepiali fungal strain. This strain has been generally accepted as true anamorph of wild Ophiocordyceps sinensis. It is only found at high altitude area like Himalayan plateau where atmospheric pressure is very low. Most of researches about P. hepiali and artificial mycelial cultivation have been done around mean sea level pressure. Then new experimental set up was developed and described. The apparatus permitted growth of mycelia under different pressure levels while other micro environmental conditions were carefully controlled. Potato dextrose broth was used as liquid media. As solid and semi solid media, sorghum base media and potato dextrose agar were prepared. Results of mycelial growth under hypobaric pressures and hyperbaric pressure were compared with mycelial growth of atmospheric pressure and hence growth influence has been shown. Specially, -100 mmHg treated sample showed significantly highest growth in both solid media and semi solid media. In semi solid media, -100 mmHg was not significant with other reduced pressure treatments. Meanwhile, -150 mmHg treated samples showed significantly highest mycelial growth of liquid media and -150 mmHg of pressure adversely affected on water contents of solid growing media. This may be an effect of pressure on enzymatic activities, protein and fatty acid of plasma membrane. As well as, pressure changes equilibrium of biochemical reactions, bond of some molecules and partial pressure of air molecules. Further molecular and biochemical researches are required to evaluate the possible stimulation of mycelial growth through hypobaric and hyperbaric treatments.