Cell damage and recovery in cryopreserved microphytobenthic diatoms

Area of Science:

• Marine biology
• Phycology
• Cryobiology

Background:

• Microphytobenthic diatoms are crucial primary producers in aquatic ecosystems.
• Effective cryopreservation methods are needed for long-term storage and research of diatom species.
• Understanding mechanical injury during cryopreservation is key to improving cell viability.

Purpose of the Study:

• To investigate the mechanical injuries and post-preservation recovery of two diatom species during cryopreservation.
• To compare the efficacy of direct freezing versus two-step cooling with and without dimethyl sulfoxide (Me(2)SO).

Main Methods:

• Cryopreservation of Amphora coffeaeformis and Navicula transitans var. derasa f. delicatula.
• Exposure to direct liquid nitrogen freezing and two-step cooling protocols.
• Assessment of cell integrity and chloroplast damage post-thaw.
• Evaluation of post-thaw viability.

Main Results:

• Amphora coffeaeformis cells showed resilience, surviving direct freezing without cryoprotectant.
• Navicula delicatula chloroplasts were susceptible to mechanical injury from freezing.
• Two-step cooling combined with dimethyl sulfoxide (Me(2)SO) significantly reduced mechanical injury.
• The cryoprotectant enhanced post-thaw viability for both diatom species.

Conclusions:

• Diatom species exhibit differential tolerance to cryopreservation stress.
• Dimethyl sulfoxide (Me(2)SO) is an effective cryoprotectant for minimizing mechanical injury in diatoms.
• Optimized two-step cooling protocols improve cryopreservation success for microalgae.