Phelps P, Giddings T H, Prochoda M, Fall R
J Bacteriol. 1986 Aug;167(2):496-502. doi: 10.1128/jb.167.2.496-502.1986.
Several ice-nucleating bacterial strains, including Erwinia herbicola, Pseudomonas fluorescens, and Pseudomonas syringae isolates, were examined for their ability to shed ice nuclei into the growth medium. Only E. herbicola isolates shed cell-free ice nuclei active at -2 to -10 degrees C. These cell-free nuclei exhibited a freezing spectrum similar to that of ice nuclei found on whole cells, both above and below -5 degrees C. Partially purified cell-free nuclei were examined by density gradient centrifugation, chemical and enzymatic probes, and electron microscopy. Ice-nucleating activity in these cell-free preparations was associated with outer membrane vesicles shed by cells and was sensitive to protein-modifying reagents.
对几种冰核细菌菌株，包括草生欧文氏菌、荧光假单胞菌和丁香假单胞菌分离株，进行了检测，以考察它们向生长培养基中释放冰核的能力。只有草生欧文氏菌分离株能释放出在-2至-10摄氏度具有活性的无细胞冰核。这些无细胞冰核在-5摄氏度以上和以下均呈现出与全细胞上发现的冰核相似的冷冻谱。通过密度梯度离心、化学和酶促探针以及电子显微镜对部分纯化的无细胞冰核进行了检测。这些无细胞制剂中的冰核活性与细胞释放的外膜囊泡有关，并且对蛋白质修饰试剂敏感。
