疫霉属菌种的液氮超低温保藏

对疫霉属的15个种68株菌和霜疫霉2株菌进行了液氮超低温的保藏试验并得到成功。比较了冷冻速度、保护剂和解冻速度对菌存活的影响。严格控制每分钟降温摄氏1度直到-40℃后再放入液氮罐中,对疫霉和霜疫霉来说都是非常必要的。这种降温程序可通过简单设备人工操作达到。而直接由室温降到-150℃以下会损伤菌种以致死亡。在所用的保护剂中,不论10％甘油还是5-15％二甲基亚砜都能起到保护作用。尚看不出对那种保护剂有特别的要求,似可任意选用。至于解冻条件,由液氮中取出放置在38℃水浴中快速融化与在20℃水浴中中等速度融化效果相等,对菌的成活都没有太大影响。我们的试验肯定了在有保护剂存在下,用慢速冷冻可以在液氮中保存疫霉和霜疫霉。

STORAGE OF PHYTOPHTHORA CULTURES IN LIQUID NITROGEN ULTRA LOW TEMPERATURE

68 strains of 15 species of Phytophthora and two strains of Peronophythora litchii were successfully preserved in liquid nitrogen ultra low temperature.The effects of freezing rate,cryoprntectants and thawing rate on the viability of fungi were examined.It is essential for Phytophthora and Peronophythora that crucially controlling of freezing rate by lowering temperature 1 centigrade degree per minute to -40℃ and then removing to liquid nitrogen.This procedure could be manipulated with a simple devised equipment easily.Whe- reas directly removing from room temperature to ultra low temperature caused serious damage and death of fungi.The protectants used either 10% glycerol or 5—15% dimethyl sulfoxide could prevent fungi from damage.No preference of which protectants was shown in tested, therefore either one could be used.The thawing condition either rapid thawing by removing vials from liquid nitrogen to 38℃ water bath or moderate rate by thawing in 20℃ water bath did not show significant influence on the viability of Phytophthora and Peronophythora.Our results confirm that with suitable protective agent and slow freezing rate Phytophthora species and Peronophythora litchii can be preserved in liquid nitrogen.