Maintenance of cyanotoxin production by cryopreserved cyanobacteria in the New Zealand culture collection

Abstract

A culture collection of freshwater planktonic and benthic cyanobacteria collected from sites across New Zealand has been established at the Cawthron Institute, Nelson, New Zealand. Limited resources led to uncertainty regarding the longterm maintenance of this collection. The present study demonstrates cryopreservation to be a viable method for long-term storage of cyanobacteria. Seventeen of 20 strains evaluated were successfully cryopreserved using the permeating cryopreservation agent dimethyl sulfoxide (Me 2 SO), at a final concentration of 15% (v/v). Cyanotoxin analysis was undertaken on selected strains known to produce microcystins, nodularin, anatoxin-a, and saxitoxins. All strains retained their ability to produce these toxins following cryopreservation.

Characterisation of freshwater and marine cyanobacteria in the Hokianga region, Northland, New Zealand

“…CAWBG-16, isolated in New Zealand, produces primarily desmethylmicrocystin-LR (Wood et al 2008). Initial salinity experiments demonstrated that CAWBG16 could survive (but not undergo division) in seawater of 30 ppt (data not shown).…”

“…Strains were cryopreserved under liquid nitrogen as described in Rhodes et al (2006) and Wood et al (2008). These cultures are now maintained in a cryobank at the Cawthron Institute Culture Collection of Microalgae (CICCM; http://cultures.caw thron.org.nz/).…”

Cryopreservation of cyanobacteria

“…Whilst for some cyanobacteria, lyophilization is an alternative option to cryogenic storage Silva, Ferrari, and Silva, 2007), preservation in liquid nitrogen should be the preferred approach. This is because the stability of production of primary and secondary metabolites has been confirmed after ultralow-temperature storage (Hédoin et al, 2006;Wood et al, 2008), whereas, although there are no data for cyanobacteria, production losses of secondary metabolites have been reported in suboptimally lyophilized fungi (Ryan et al, 2003).…”

Cryobanking of aquatic species

“…Over 250 of these strains are held cryopreserved in liquid nitrogen. The collection includes a number of unique species and strains and underpins applied and fundamental research including: characterisation of algal toxin producers and their toxins, phytoplankton monitoring, validation of molecular-based detection tools, as well as research for bioactive and novel compounds (Rhodes et al, 2006; Woods et al, 2008). …”