Effect of freezing and thawing on cell membranes of Lentinus edodes, the shiitake mushroom

Area of Science:

• Mycology
• Cell Biology
• Cryobiology

Background:

• Lentinus edodes (Shiitake mushroom) is a valuable edible fungus.
• Understanding cryopreservation effects on fungal cell membranes is crucial for preserving mycelial cultures.
• Cell membrane integrity is vital for fungal viability during freezing.

Purpose of the Study:

• To investigate the impact of different cooling rates on Lentinus edodes mycelium viability and cell structure.
• To correlate cellular damage with specific freezing rates.

Main Methods:

• Rapid freezing of Lentinus edodes mycelium at 50°C/min and 160°C/min.
• Slow cooling of mycelium at 1°C/min.
• Microscopic examination of cell membrane and organelle integrity post-freezing.

Main Results:

• Rapid freezing (50 or 160°C/min) led to complete loss of mycelial viability.
• Observed cellular damage included plasmalemma rupture and organelle alterations in rapidly frozen samples.
• Slow cooling (1°C/min) resulted in 80% viability recovery, though some cells still showed damage.

Conclusions:

• Rapid freezing protocols are detrimental to Lentinus edodes mycelium viability due to severe cell membrane damage.
• Cellular responses to freezing are heterogeneous within the mycelium, even under slow cooling conditions.
• Optimizing cryopreservation requires considering the differential susceptibility of individual cells to thermal stress.