# Antimicrobial Efficacy of Edible Mushroom Extracts: Assessment of Fungal Resistance
## 3 Results and Discussion
### Antifungal Activity of T. camphoratus Methanol Extract (TcM)
#### 3.2.2 Antifungal Activity Test of TcM on Apple or Grape JA (Complex Medium)  
The antifungal activity of TcM was determined further against foodborne fungal pathogens/contaminants by monitoring their radial growth on food matrices, apple, or grape JA containing 0.8 or 1.6% (\(w/v\)) of TcM. As determined in PDA (see Section 3.2.1), there were incremental increases in TcM antifungal efficacy (reduction in a fungal radial growth) in either apple or grape JA as the TcM concentration increased (Table 3), except with _A. parasitic_s on grape JA, with a similar level of susceptibility to either 0.8% or 1.6% of TcM (Table 3). \begin{table}
\begin{tabular}{c c c c} \hline
**Extract (\%; \(w/v\))** & **0.0** & **0.81** & **1.61** \\
**Fungi** & **0.0** & **0.81** & **1.61** \\ \hline _N. fischeri_ 96468 & 100 \(\pm\) 0\% & 15 \(\pm\) 2\% & 15 \(\pm\) 0\% \\ _A. flavus_ 3357 & 100 \(\pm\) 3\% & 48 \(\pm\) 5\% & 38 \(\pm\) 0\% \\ _A. parasitic_s 5862 & 100 \(\pm\) 2\% & 54 \(\pm\) 0\% & 42 \(\pm\) 0\% \\ _P. expansum_ W1 & 100 \(\pm\) 0\% & 57 \(\pm\) 0\% & 36 \(\pm\) 11\% \\ _P. expansum_ FR2 & 100 \(\pm\) 15\% & * 91 \(\pm\) 0\% (\(p\) < 0.5)2 & * 82 \(\pm\) 5\% (\(p\) < 0.1) 2 \\ _P. expansum_ W2 & 100 \(\pm\) 0\% & 43 \(\pm\) 16\% & 43 \(\pm\) 4\% \\ _P. expansum_ FR3 & 100 \(\pm\) 6\% & * 70 \(\pm\) 0\% 2 & 40 \(\pm\) 23\% (\(p\) < 0.05) \\ \hline Average & 100 \(\pm\) 4\% & 54 \(\pm\) 3\% & 42 \(\pm\) 6\% \\ \hline \end{tabular} 1
[FOOTNOTE:1]Footnote 1: footnotetext: _p \(<\) 0.005 except where noted. Student’s \(t\)-test for paired data (% radial growth) from each concentration (0.8 and 1.6%) vs. no treatment control (0.0%). 2.* Tolerant growth compared to the respective wild type strain, W1 or W2._ \\ \end{table} 
Table 2: Antifungal activity of TcM on PDA (% radial growth compared to no treatment control). The results show that the antifungal efficacy of TcM was relatively higher in apple JA than in grape JA; average % radial growth in apple JA was 65 \(\pm\) 13% or 41 \(\pm\) 16% at 0.8% or 1.6% of TcM, respectively, while that in grape JA was 75 \(\pm\) 18% or 64 \(\pm\) 15% at the same concentrations of TcM. Hence, the order of antifungal efficacy was high to low: (a) PDA > apple JA > grape JA at 0.8%, and (b) PDA, apple JA > grape JA at 1.6%. It seems that the ingredients in the JA (complex medium) might negatively affect the antifungal efficacy of TcM when compared to PDA (defined medium). Of note, interference of the efficacy of antifungal agents by the ingredients of food matrices has been previously documented. For instance, the polyene drug natamycin (NAT) is a redox-active antifungal molecule commercially applied for control of fungi infecting various crops or contaminating processed foods [51; 52; 53; 54; 55]. We previously observed that while the antifungal efficacy of NAT (tested against filamentous fungi) was generally enhanced with increasing doses of NAT in JA, the level of NAT efficacy varied depending on the types of JA tested [35]. Therefore, it can be concluded that the ingredients in food matrices could interfere with the antifungal efficacy of sanitary compounds. Changes in NAT efficacy in response to food ingredients such as organic acids, salts, etc., have been documented further in different food matrices [35 and references therein]. Furthermore, as observed in PDA (see Section 3.2.1), two _P. expansum_ antioxidant mutants (FR2, FR3) showed 8% to 100% of higher growth rate (namely, tolerance) to TcM on JA at both 0.8% and 1.6% of TcM, when compared to their respective wild type strains W1 and W2 (Table 3). Resistance of Mitogen-Activated Protein Kinase (MAPK) Mutants of A. fumigatus and P. expansum to SA: Proof-of-Concept  
As mentioned previously, the fungicidal effect of the commercial fungicide FLU is exerted via the \"intact\" oxidative (osmotic) stress signaling system in fungi, namely the MAPK pathway [49]. FLU disrupts fungal growth by triggering unusual, excessive stimulation of the oxidative (osmotic) stress signaling MAPK system, thus causing cellular energy drain [49].