冷冻保护剂和储藏条件对海洋酵母冻干粉活性的影响

Effects of Cryoprotectants and Storage Conditions on the Survivial and Biocontrol-activity of Freeze-dried Rhodosporidium paludigenum

海洋拮抗酵母Rhodosporidium paludigenum作为生防保鲜剂在控制水果采后真菌类病原菌中表现出了良好的抑制效果,然而生防制剂要真正取代化学杀菌剂,必须以产品的形式投入市场,即实现其商品化生产。实验将该拮抗酵母制成冻干粉,研究冻干保护剂和储藏条件对海洋酵母干粉稳定性的影响。结果显示,海藻糖作为保护剂可以显著地提高酵母干粉的存活率和生防活性,用5%的海藻糖作保护剂,存活率为42%,而对照仅为3%。研究还发现,酵母细胞的存活率与其胞内海藻糖含量具有一定的相关性。另外,储藏实验表明,低温(4℃)可以较好地保持酵母干粉的存活力。而常温(25℃)下储藏1个月,每克干粉中酵母活细胞数下降5个数量级,因此常温不适合储藏该新型拮抗酵母生防制剂。

The aim of this study is to survey the effects of cryoprotectants and storage conditions on the viability level and biocontrol activity of freeze-dried Rhodosporidium paludigenum. The marine antagonistic yeast R. paludige- hum shows good inhibition on the control of postharvest pathogenic fungus of fruit in our previously works. However, to make the yeast as biocontrol agent replacement of the synthetic fungicides, it must be put into market in the form of product. Here the yeast was prepared into powder by freeze drying and investigated cryoprotectants＇ effects on its sta- bility. The experiments revealed that using 5% trehalose as cryoprotectant could greatly improve the viability and bio- control activity of R. paludigenum. The survival rate was 42% , while the control was only 3%. And the viability of the yeast cells had certain relationship to the intracellular trehalose. Storage experiments showed that refrigerant tem- perature （4℃ ） could make the viability of the dried yeast better. Because the living cells decreased 5 orders of mag- nitude after having been in storage for only one month, normal temperature （25℃ ） was not suitable for storing this biocontrol agent.