Saprolegnia spp. water moulds are opportunistic pathogens that can cause economic losses to aquaculture. The diseases caused by them are difficult to control since use of the effective drug, malachite green oxalate, is no longer permitted in several regions (including the European Union and USA). To develop an effective control strategy, Saprolegnia isolates must be maintained in the laboratory. Cryopreservation is a useful solution for long-term maintenance; however, at present, there is no developed protocol for the cryopreservation of Saprolegnia spp. Here, we isolated and identified three Saprolegnia species, S. parasitica, S. australis and S. ferax, and developed a deep-freezing protocol that enables the long-term archiving of these species. The survival and growth rates of isolates kept at -80 °C for 3, 6, 9 and 12 months, were tested and compared among the species examined. Although the growth rates of frozen isolates were significantly lower than those of the control (i.e. non-frozen) isolates, the overall survival rate (>90%) indicated the effectiveness of the technique developed. Thus, the protocol developed appears to be a promising method for the long-term preservation of Saprolegnia isolates and may facilitate the creation of stock collections.

中文翻译：

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三种水霉属 (Oomycota) 的低温保存：水霉属长期存档的初步证据

水霉属 水霉菌是机会性病原体，可对水产养殖造成经济损失。由它们引起的疾病很难控制，因为有效药物孔雀绿草酸盐在一些地区（包括欧盟和美国）不再被允许使用。为了制定有效的控制策略，水霉分离株必须保存在实验室中。冷冻保存是长期维护的有用解决方案；然而，目前还没有用于水霉属低温保存的开发方案。在这里，我们分离并鉴定了三种水霉属物种，即寄生性水霉、澳大利亚水霉和 S. ferax，并开发了一种能够对这些物种进行长期存档的深度冷冻方案。分离株的存活率和生长率保持在 -80 °C 3、6、9 和 12 个月，在被检查的物种之间进行了测试和比较。虽然冷冻分离株的生长率明显低于对照（即非冷冻）分离株的生长率，但总体存活率 (>90%) 表明所开发技术的有效性。因此，所开发的协议似乎是一种长期保存水霉分离物的有前途的方法，并可能促进库存收藏的创建。