Proteomic analysis of the inhibitory effect of chitosan on Penicillium expansum

Abstract The antimicrobial effect of chitosan on Penicillium expansum, a major postharvest pathogen of pome fruit, and the possible mechanisms involved in its effect were examined in this study. Chitosan strongly inhibited spore germination and hyphal growth of P. expansum. Light microscopy and transmission electron microscopy observations revealed that chitosan also caused morphological changes in hyphae and conidia, such as abnormal branching and vacuolation. Proteomic changes in P. expansum after chitosan treatment were analyzed by two-dimensional electrophoresis (2-DE) and mass spectrometry (MS) analysis, and 26 proteins were ambiguously identified and categorized based on their putative biological function. Proteins related to DNA or protein biosynthesis, carbohydrate metabolism and energy production were decreased in relative protein abundance, while proteins involved in antibiotics resistance and defense response increased in relative protein abundance. Changes in abundance of these identified proteins were in accordance to the observed physiological and morphological changes of the fungi cells. Altogether, these experimental results provide a detailed illustration of the responses to chitosan in P. expansum, and widen our knowledge on the potential antifungal mechanisms of chitosan.

摘要：本研究考察了壳聚糖（chitosan）对仁果类水果主要采后病原菌扩展青霉（Penicillium expansum）的抗菌作用及其潜在作用机制。结果显示，壳聚糖可显著抑制扩展青霉的孢子萌发与菌丝生长。光学显微镜与透射电子显微镜观察表明，壳聚糖还会诱导扩展青霉菌丝与分生孢子发生形态改变，如异常分枝与空泡化。本研究通过二维凝胶电泳（2-DE）与质谱（MS）分析，对壳聚糖处理后的扩展青霉进行蛋白质组学变化分析，共鉴定出26种蛋白质（鉴定结果存在一定不确定性），并依据其推测的生物学功能进行分类。与DNA或蛋白质生物合成、碳水化合物代谢及能量产生相关的蛋白质，其相对丰度显著下调；而与抗生素抗性及防御反应相关的蛋白质相对丰度则明显上调。上述鉴定蛋白质的丰度变化，与观测到的真菌细胞生理及形态变化相符。综上，本研究的实验结果详细阐明了扩展青霉对壳聚糖的响应机制，拓宽了我们对壳聚糖潜在抗真菌作用机制的认知。