Bonaterra Anna, Camps Jaume, Montesinos Emilio
Institute of Food and Agricultural Technology-CIDSAV-CeRTA, University of Girona, Campus Montilivi, 17071 Girona, Spain.
FEMS Microbiol Lett. 2005 Sep 1;250(1):1-8. doi: 10.1016/j.femsle.2005.06.028.
The application of the biocontrol agent Pantoea agglomerans EPS125 to unwounded fruits was practically ineffective for control of postharvest blue mould caused by Penicillium expansum when the treatment and subsequent wounding and pathogen inoculation were separated by periods of unfavourable conditions. This was due to a rapid decrease in viability of the alocthonous introduced biocontrol agent in the intact peel surface. A system for osmoadaptation of the biocontrol agent was developed by combining saline osmotic stress and osmolyte amendment to the growth medium. Osmoadapted cells accumulated trehalose and glycine betaine (GB) intracellularly and showed a higher tolerance to desiccation than non-osmoadapted cells. Osmoadaptation in NaCl plus GB during inoculum preparation increased considerably survival on the peel surface of apple fruits. This effect was significant under low relative humidity (RH) and fluctuating RH conditions, but was not significant at high RH. Osmoadaptation significantly improved blue mould control under conditions where the standard biological control treatments were ineffective. The rot diameter was significantly reduced in apple fruits which were treated with EPS125 and incubated for several days under low, high or fluctuating RH, followed by wounding and inoculation of P. expansum. Growth of EPS125 with NaCl, either with or without the addition of GB, was an effective osmoadaptation treatment for improving blue mould rot control. However, the addition of GB to the NaCl amended growth medium increased 4-5-fold growth rate and OD of the cultures. This is an advantage for mass production of P. agglomerans EPS125 in a NaCl amended growth medium.
当处理与随后的伤口形成及病原菌接种之间存在一段不利条件时，将生防菌成团泛菌EPS125应用于未受伤的果实上，对于控制由扩展青霉引起的采后蓝霉病实际上是无效的。这是由于引入的外来生防菌在完整果皮表面的活力迅速下降。通过将盐渗透胁迫和向生长培养基中添加渗透保护剂相结合，开发了一种生防菌的渗透适应系统。经过渗透适应的细胞在细胞内积累海藻糖和甘氨酸甜菜碱（GB），并且比未经过渗透适应的细胞表现出更高的耐干燥性。在接种物制备过程中，在NaCl加GB条件下进行渗透适应可显著提高苹果果实果皮表面的存活率。在低相对湿度（RH）和波动的RH条件下，这种效果显著，但在高RH条件下不显著。在标准生物防治处理无效的条件下，渗透适应显著改善了对蓝霉病的控制。用EPS125处理并在低、高或波动的RH条件下培养几天，随后进行伤口形成并接种扩展青霉，苹果果实的腐烂直径显著减小。用NaCl培养EPS125，无论添加或不添加GB，都是一种有效的渗透适应处理方法，可改善对蓝霉腐烂病的控制。然而，向NaCl改良的生长培养基中添加GB可使培养物的生长速率和OD增加4至5倍。这对于在NaCl改良的生长培养基中大规模生产成团泛菌EPS125来说是一个优势。
