Synergistic Effect of Polyglycerol and DMSO for Long-Term Cryopreservation of <i>Stichococcus</i> Species

Herein, we present a significant advancement in long-term cryopreservation techniques for microalgae <i>Stichococcus</i> species using a combination of linear polyglycerol (<i>lin</i>PG) and dimethyl sulfoxide (DMSO). The technique was tested on three <i>Stichococcus</i> species: <i>Stichococcus bacillaris</i>, <i>Stichococcus deasonii</i>, and <i>Stichococcus minor</i>, which showed long-term viability and recovery rates superior to those when treated with a traditional cryoprotectant only. While DMSO alone enabled high cell recovery rates for all species after 1 week of cryopreservation, the rates for some of them dropped below 50% after 26 weeks of cryopreservation. Treating the cells with a combination of <i>lin</i>PG and DMSO raised the recovery rates for all three <i>Stichococcus</i> species to above 92% after long-term cryopreservation. Our findings indicate that <i>lin</i>PG in combination with DMSO offers a synergistic and effective solution for maintaining cell integrity and functionality during long-term cryopreservation of microalgae.