Wu Z, Kan F W K, She Y-M, Walker V K
Department of Biology, Queen's University, Kingston, Ontario, Canada K7L 3N6.
Prikl Biokhim Mikrobiol. 2012 Jul-Aug;48(4):403-10.
Microbial communities found on the surface of overwintering plants may be exposed to low temperatures as well as multiple freeze-thaw events. To explore the adaptive mechanisms of these epiphytes, with the objective of identifying products for freeze-protection, enrichment libraries were made from frost-exposed leaves. Of 15 identified bacteria from 60 individual clones, approximately half had ice-association activities, with the great majority showing high freeze-thaw resistance. Isolates with ice nucleation activity and ice recrystallization inhibition activity were recovered. Of the latter, two (Erwinia billingiae J10, and Sphingobacterium kitahiroshimense Y2) showed culture and electron microscopic evidence of motility and/or biofilm production. Mass spectrometric characterization of the E. billingiae extracellular polymeric substance (EPS) identified the major proteins as 35 kDa outer membrane protein A and F, supporting its biofilm character. The addition of the EPS preparation increased the freeze-thaw survival of the more susceptible bacteria 1000-10000 times, and protection was at least partially dependent on the protein component.
在越冬植物表面发现的微生物群落可能会面临低温以及多次冻融事件。为了探索这些附生植物的适应机制，以确定用于防冻的产品，从受冻叶片中构建了富集文库。在从60个单独克隆中鉴定出的15种细菌中，约一半具有与冰相关的活性，绝大多数表现出高抗冻融性。回收了具有冰核活性和抑制冰重结晶活性的分离物。在后者中，两种（比氏欧文氏菌J10和北广岛鞘氨醇杆菌Y2）显示出运动性和/或生物膜形成的培养和电子显微镜证据。对比氏欧文氏菌胞外聚合物（EPS）的质谱表征确定主要蛋白质为35 kDa外膜蛋白A和F，支持其生物膜特性。添加EPS制剂使更敏感细菌的冻融存活率提高了1000 - 10000倍，并且保护至少部分依赖于蛋白质成分。
