Potential of osmoadaptation for improving Pantoea agglomerans E325 as biocontrol agent for fire blight of apple and pear

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• 作者：P.L. Pusey^a ; ^{larry.pusey@tfrl.ars.usda} ; ^{larry.pusey@ars.usda.gov} ; C. Wend^b
• 关键词：Erwinia amylovora ; Malus domestica ; Trehalose ; Xanthan gum
• 刊名：Biological Control
• 出版年：2012
• 期刊代码：110_10499644
• 类别：abs
• 出版时间：July, 2012
• 卷：62
• 期：1
• 页码：29-37
• 文件大小：561 K

摘要

Pantoea agglomerans biocontrol strain E325 is the active ingredient in a commercial product for fire blight, a destructive disease of apple and pear initiated by Erwinia amylovora in flowers. Osmoadaptation, involving the combination of saline osmotic stress and osmolyte amendment to growth media, was investigated to improve the epiphytic colonization by E325 on apple flowers, particularly in dry climates. E325 was osmoadapted in nutrient yeast dextrose broth and in the commercial fermentation medium, both amended with NaCl and glycine betaine according to previous research. The bacterium was cultured and freeze dried with cryoprotectants at an ARS-USDA laboratory (Wenatchee, WA) and a commercial facility (Pasco, WA) prior to treating apple flowers in an orchard where relative humidity (RH) averaged <50%. On orchard flowers and on detached crab apple flowers, osmoadaptation generally did not affect colonization of E325 on flower stigmas or nectar-rich hypanthia. The exception was the significant advantage of osmoadapted E325 on hypanthia of detached flowers at 70%RH, resulting in osmotic conditions marginally conducive for bacteria. Osmoadaptation proved most beneficial for increasing E325 survival during freeze drying and storage prior to orchard application. It also complemented cryoprotection, improving overall stability of freeze dried preparations of this biocontrol agent.