# Antimicrobial Efficacy of Edible Mushroom Extracts: Assessment of Fungal Resistance
## 3 Results and Discussion
### Antibacterial Activities of T. camphotatus Methanol (TcM) or Water (TcW) Extracts  
Antibacterial activity of three mushroom extracts were explored further against the wild type foodborne bacteria. We found that, as is the case in fungi described above, only TcM exhibited potent antibacterial activity against _S. aureus_ and _Lactobacillus_ spp., while TcW possessed limited antibacterial activity against _L. monocytogenes_ (Table 5) (note that the lack of any antibacterial activity by the _A. blazei_ and _G. lucidium_ extracts are not shown.)  
The following were determined: (a) In the species of _Lactobacillus_, the level of antibacterial activity of TcM increased with the concentrations of TcM. _L. acidophilus_ showed the highest susceptibility to TcM (67% growth inhibition at 0.625% TcM), followed by _L. monocytogenes_ (30% growth inhibition at 0.625% TcM) and _L. reuteri_ (40% growth inhibition at 1.25% TcM; no inhibition at 0.625% TcM); (b) TcW possessed a limited antibacterial efficacy; only _L. monocytogenes_ showed around 35% growth inhibition at the highest concentration tested (10% TcW); (c) _S. aureus_ exhibited 41% of growth inhibition at 10% of TcM, while _E. coli_ and _S. enterica_ did not exhibit any susceptibility to TcM or TcW; and (d) as determined in fungi, it seems that \"compound-strain specificity\" also exists for the bacterial responses to TcM. A similar type of differential antibacterial activity was observed when extracts from tomato (leaves, stems, fruit) were applied as antibacterial agents against bacterial pathogens [40]. As stated above for the fungal study, elucidation of the comprehensive  
\begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline
**Treatment** & **Extracts** & _E. coli_ & _S._ & _S._ & _L._ & _L._ & _L._ \\  & **(\%)** & **K12** & _ enterica_ & _ aureus_ & _ monocytogenes_ & _acidophilus_ & _reuteri_ \\ \hline DMSO & & 0 & 0 & 0 & 0 & 0 & 0 \\ Gentamicin, 10 \(\mu\)g (final concentration) & & 100 & 100 & 100 & 100 & 100 \\ \hline _T._ & & & & & & & \\ Water (TcW) & 5 & 0 & 0 & 0 & 50 & 83 & 47 \\  & 2.5 & 0 & 0 & 0 & 40 & 75 & 40 \\  & 1.25 & 0 & 0 & 0 & 30 & 67 & 40 \\  & 0.625 & 0 & 0 & 0 & 30 & 67 & 0 \\ \hline _T._ & & & & & & & \\ _camphotatus_ & 10 & 0 & 0 & 0 & 35 & 0 & 0 \\ Water (TcW) & 5 & 0 & 0 & 0 & 0 & 0 & 0 \\  & 2.5 & 0 & 0 & 0 & 0 & 0 & 0 \\  & 1.25 & 0 & 0 & 0 & 0 & 0 & 0 \\  & 0.625 & 0 & 0 & 0 & 0 & 0 & 0 \\ \hline \hline \end{tabular}  
* A disc diffusion assay was performed with either vehicle, antibiotic controls, or mushroom extracts at 0.625, 1.25, 2.5, 5, or 10% (_e_/_e_). The numerical values in each strain columns (0 to 100) indicate % growth inhibition compared to that determined with gentamicin (10 \(\mu\)g, positive control).  
\end{table}
Table 5: Antibacterial activity (% zone of inhibition compared to the Gentamicin control) of _T. camphotatus_ extracts \({}^{1}\).  
mechanism of \"compound--strain specificity\" as well as the functional response(s) of antioxidant signaling mutants to mushroom extracts (namely, tolerant vs. sensitive responses) in the bacterial study also warrants future in-depth investigation.