Expanding the toolbox for cryopreservation of marine and freshwater diatoms

Abstract

Diatoms constitute the most diverse group of microalgae and have long been recognised for their large biotechnological potential. In the wake of growing research interest in new model species and development of commercial applications, there is a pressing need for long-term preservation of diatom strains. While cryopreservation using dimethylsulfoxide (DMSO) as a cryoprotective agent is the preferred method for long-term strain preservation, many diatom species cannot be successfully cryopreserved using DMSO. Therefore, in this study, we studied cryopreservation success in six different diatom species, representing the major morphological and ecological diatom groups, using a range of DMSO concentrations and Plant Vitrification Solution 2 (PVS2) as an alternative cryoprotectant to DMSO. In addition, we tested whether suppressing bacterial growth by antibiotics accelerates the post-thaw recovery process. Our results show that the effects of cryoprotectant choice, its concentration and the addition of antibiotics are highly species specific. In addition, we showed that PVS2 and antibiotics are useful agents to optimize cryopreservation of algae that cannot survive the traditional cryopreservation protocol using DMSO. We conclude that a species-specific approach will remain necessary to develop protocols for diatom cryopreservation and to increase their representation in public culture collections.

Effects of Cryopreservation on Microparticles Concentration, Procoagulant Function, Size Distribution, and Morphology

“…DMSO is a widely used reagent in cell biology. It can dehydrate cells during cryopreservation, thereby preventing the formation of ice crystals in the intracellular environment [32]. Our results showed that compared to the fresh group, the total MPs concentration, the concentration of annexin V-positive MPs, the concentration of BDMPs, the procoagulant function of MPs, the MPs size distribution, and the morphology of the MPs were significantly changed in the DMSO group; however, there was no difference between the DMSO group and the DMSO-free group.…”

A time-calibrated multi-gene phylogeny provides insights into the evolution, taxonomy and DNA barcoding of the Pinnularia gibba group (Bacillariophyta)

“…To date, no experiments tested the tolerance of diatoms to low pressure, but we may assume that under such conditions they may suffer from desiccation which is lethal for many diatoms (Souffreau et al 2010(Souffreau et al , 2013a. Similarly, it seems that many diatoms are intolerant to freezing below -40°C, although there are some notable exceptions (Stock et al 2018). In addition to passive dispersal by means of abiotic vectors, biotic vectors might also play a role.…”

Temporal and spatial variability of terrestrial diatoms at the catchment scale: controls on communities

“…This is also what we observed in the three cases with Pinnularia borealis Ehrenberg, H. amphioxys and H. abundans often replacing N. pusilla and Mayamaea spp. The former three taxa are very common, large terrestrial diatoms (±75 µm) and are known to be well-adapted to living in extreme environments (Dodd & Stoermer, 1962;Pipe & Cullimore, 1984;Stock et al, 2018;Van Dam, Mertens & Sinkeldam, 1994). These diatoms are considered to be slow growers, since they spend a large part of their energy in developing complex structures to withstand (very) harsh conditions (Pinseel et al, 2019;Ress, 2012).…”