Stability assay of antagonistic activity of Serratia plymuthica strain UBCR_12 under various environmental factors

Serratia plymuthica strain UBCR_12 exhibited promising antifungal activity against Colletotrichum gloeosporioides. The development of this strain for field use requires a certain level of stability towards various environmental exposures that might occur in the natural condition. This study was aimed to evaluate the stability level of antifungal activity produced by the culture supernatants of S. plymuthica strain UBCR_12 under several environmental factors. Antifungal assay of this strain was performed through the application of culture supernatants under several parameters and was performed in five technical replications. Data were confirmed statistically using one-way and two-way ANOVA and significance among treatments were verified through DNMRT with a p<0.05. The antagonistic effect of this strain varied in each environmental parameter tested. The highest suppression was recorded at pH 8.0 [30.32%] after eight days of application indicating that the alkaline condition might trigger its defense mechanism. Other parameters showed quite similar inhibition efficacy, such as 24.06% [100 C for 45 minutes] and 21.15% [CaCl₂ addition]. Compared to control, this strain could suppress anthracnose-causing fungi up to 24.06% suggesting that its antifungal activity was considered as quite stable over the presence of heat and calcium.