荒漠地衣糙聚盘衣共生菌耐旱生物学研究及液体优化培养

为从荒漠地衣共生菌中筛选耐旱基因,以分离自荒漠地衣糙聚盘衣Glypholecia scabra的共生菌为实验材料,研究了在水分胁迫条件下其耐旱生物学特性的变化情况。结果显示:在低水分活度条件下,糙聚盘衣共生菌通过积累可溶性糖含量维持细胞渗透压,通过增加抗氧化物质多酚及还原型谷胱甘肽的含量清除活性氧物质。初步推测与多酚和还原型谷胱甘肽代谢相关基因为耐旱基因的候选基因,在水分活度aw=0.90,aw=0.85时,可以诱导候选基因大量表达。此外,为给克隆与表达分析耐旱基因提供足够菌种,通过Plackett-Barman实验和正交实验对其培养条件进行了优化。其最佳液体培养基为:土豆浸汁1L,葡萄糖15g,大豆蛋白胨2g,钴胺素(VB12)200μg;最佳培养条件为:温度18℃,pH6.3,装瓶量150mL/250mL,摇床转速为100r/min。糙聚盘衣共生菌生长曲线显示,通过优化培养条件可使其生物量显著提高。

Desiccation-tolerance biological research and liquid culture of the mycobiont isolated from the desert lichen Glypholecia scabra

In order to isolate the drought-resistant gene from the mycobiont of desert lichens, the desiccation-tolerance biological research and liquid culture were performed. The mycobiont isolated from the desert lichen Glypholecia scabra, was studied under the water stress. The results showed that the mycobiont isolated from G. scabra would accumulate soluble sugars and increase the concentration of total phenols and reduce glutathione (GSH) to protect itself from low water activities. It could be inferred that the genes relating to the metabolic pathways of phenols and GSH, may likely to be the candidates of drought-tolerance genes for cloning and expression analysis at a_w=0.90 and a_w=0.85. Additionally, in order to provide enough materials for cloning and expression analysis, optimal liquid culture conditions of the mycobiont isolated from G scabra were studied using Plackett-Burman design and orthogonal arrays. The optimized medium (pH6.3) consisted of 15g glucose, 2g soy peptone, and 200μg Vitamin B_12in 1L potato extract. 150mL medium filled in 250mL triangular flask was shaken under revolving speed of 100r/min, at 18℃. The growth curve showed that the biomass of the mycobiont isolated from G scabra was improved significantly under the optimized conditions.