Assessing the Benefits of Antioxidant and Antibiotics Treatments for Cryopreservation of the Model Alga Ectocarpus Siliculosus and the Endemic Alga Acinetospora Asiatica

BACKGROUND: Cryopreservation in liquid nitrogen is a suitable technique for preserving seaweeds, a group of photosynthetic organisms with many applications. Although there are some standard protocols for seaweed cryopreservation, most rely on expensive controlled-rate coolers. Moreover, several factors, such as the use of antioxidants or antibiotics, remain unexplored. OBJECTIVE: To test the effect of 2-mercapthoethanol (antioxidant) and antibiotic mixtures on the cryopreservation of the model alga Ectocarpus siliculosus and the endemic brown seaweed Acinetospora asiatica using a low-tech passive rate cooler. MATERIALS AND METHODS: 2mercaptoethanol was added to the cryoprotectant (CPA) solution, while antibiotic mixtures were included in the culture medium during the recovery process. In addition, two CPA solutions were tested on E. siliculosus. RESULTS: After two weeks of recovery, the treatment comprising PSC antibiotic mixture (Penicillin G, streptomycin, and chloramphenicol) showed a significant increase in post-thaw viability. Antioxidant treatment did not improve viability. The highest viabilities for E. siliculosus and A. asiatica were 64-83%, and 83-87%, respectively, using 10% glycerol + 10% proline as CPA solution. CONCLUSION: E. siliculosus and A. asiatica were successfully cryopreserved using a low-tech passive rate cooler, 10% glycerol + 10% proline solution, and antibiotic treatment. The highest post-thaw viabilities (64-87%) reported for PSC antibiotic mixture suggest the potential benefits of using antibiotics during post-thaw recovery of marine macroalgae. This study is the first report on the cryopreservation of A. asiatica.