College of Food Science and Technology, Huazhong Agricultural University, Wuhan, Hubei, China.
Aquatic Vegetable Preservation&Processing Technology Engineering Center of Hubei Province, Wuhan, Hubei, China.
Int Microbiol. 2021 Aug;24(3):415-425. doi: 10.1007/s10123-020-00157-7. Epub 2021 May 8.
Air discharge showed significant inhibition on mycelial growth and spore germination of Fusarium oxysporum, one of the main spoilage fungi in post-harvest lotus roots which is an important economic aquatic vegetable in China. However, the antimicrobial mechanism of air discharge is not clear yet. In the present study, the effects of air discharge on F. oxysporum separated from post-harvest rotten lotus roots were characterized by analyzing surface charges, cell wall permeability, and changes in chitin and chitosan including surface morphology, functional groups, degree of deacetylation, crystallinity, and C/N ratio. After air discharge treatments, alkaline phosphatase leak assay revealed that cell wall permeability of F. oxysporum was magnified. What's more, zeta potentials of F. oxysporum increased and negative charges on cell surfaces decreased. The ordered and compact molecular arrangements of chitin and chitosan in cell walls of F. oxysporum were reduced. The deacetylation degree of chitin and chitosan increased, and the C/N ratios of chitin and chitosan decreased. It was concluded from these results that air discharge caused the transformation in structures of chitin and chitosan, resulting in the exposure of positively charged amino groups and decrease of negative charges on cell surfaces which brought damage to the structure and function of F. oxysporum's cell walls.
空气放电对采后莲藕主要腐败真菌之一尖孢镰刀菌（Fusarium oxysporum）的菌丝生长和孢子萌发有显著抑制作用，莲藕是中国重要的经济水生蔬菜。然而，空气放电的抗菌机制尚不清楚。本研究通过分析表面电荷、细胞壁通透性以及壳聚糖和壳聚糖包括表面形态、官能团、脱乙酰度、结晶度和 C/N 比的变化，对从采后腐烂莲藕中分离出的尖孢镰刀菌进行了空气放电处理的特性研究。空气放电处理后，碱性磷酸酶渗漏测定表明尖孢镰刀菌的细胞壁通透性增大。此外，尖孢镰刀菌的 ζ 电位增加，细胞表面的负电荷减少。细胞壁中几丁质和壳聚糖的有序和紧密的分子排列减少。脱乙酰度增加，几丁质和壳聚糖的 C/N 比降低。综上所述，空气放电导致壳聚糖结构发生转化，导致带正电荷的氨基暴露和细胞表面负电荷减少，从而破坏了尖孢镰刀菌细胞壁的结构和功能。
