果樹炭疽病菌對食品防腐劑之感受性

Sensitivity to food antiseptics among Colletotrichum isolates collected from various fruit crops in Taiwan

為尋找替代資材防治果樹炭疽病，本研究以安全性較高的食品防腐劑測試其對數種常見果樹炭疽病菌之抑菌作用。食品防腐劑經初步篩選後，選出苯甲酸鈉、丙酸鈣及己二烯酸鉀等三種供試。供試菌株則為分離自楊桃、葡萄、印度棗、檬果、木瓜及蓮霧等六種果樹炭疽病菌（Colletotrichum spp.）各2株。藥效試驗是以微量滴定盤（microtiter plate）搭配2%洋菜或馬鈴薯葡萄糖洋菜培養基分別測試食品防腐劑對果樹炭疽病菌孢子發芽及菌絲生長的影響。試驗結果顯示，稀釋500倍（2 g/L）之苯甲酸鈉、丙酸鈣及己二烯酸鉀水溶液對供試12株炭疽病菌的孢子發芽及菌絲生長均無抑制作用。但以冰醋酸調降其水溶液酸鹼值至4，則己二烯酸鉀及苯甲酸鈉水溶液均可完全抑制供試炭疽病菌之孢子發芽與菌絲生長，且為殺菌作用；掃描式電子顯微鏡顯示該等菌株的孢子表面受到嚴重破壞，而菌絲表面所受破壞則較輕微。酸化的丙酸鈣水溶液則僅能完全抑制1株楊桃炭疽病菌之孢子發芽，其餘菌株則為部分或完全不能抑制，且該溶液對各菌株之菌絲生長亦幾無抑制。對照處理之冰醋酸水溶液（pH 4）則同於蒸餾水，皆對炭疽病菌之孢子發芽與菌絲生長無抑制。

"For seeking alternatives to synthetic chemical fungicides against plant fungal pathogens, we found some food antiseptics could be cheaper, safer and more effective to be fungicidal agents. In this study, we conducted a lab experiment to evaluate three food antiseptics for their inhibitory effects on Colletotrichum isolates collected from various fruit crops. By using microtiter plate method, it was indicated that glacial acetic acid-adjusted solutions (pH 4) of 2 g/L of potassium sorbate and sodium benzoate, respectively, were able to inhibit conidial germination and mycelial growth of all the tested isolates with damages on their cell walls. However, the acidified solution of calcium propionate could not inhibit conidial germination of the majority of isolates and mycelial growth of all the isolates. Non-acidified solutions of the three aforementioned food antiseptics and the acidified water (pH 4) had no inhibitory effect on the pathogens."