## 3 Results
### Influence of the Relative Substrate Concentrations on Oxidant Levels and Antifungal Activity
#### 3.4.1 Influence of the Relative Substrate Concentrations on Oxidant Levels
** & \multicolumn{6}{c}{_P. expansum_ **Inhibition (\%)**} \\ \hline  & **Low** & \(99\pm 2\) & \(98\pm 1\) & \({}^{\text{ab}}\) & \(10\pm 7\) & \({}^{\text{ns}}\) & \(14\pm 10\) & \(17\pm 11\) & \({}^{\text{ns}}\) & \(6\pm 5\) & \({}^{\text{ns}}\) & \(2\pm 1\) & \({}^{\text{ns}}\) \\
**25 \({}^{\circ}\)C** & **Medium Low** & \(89\pm 1\) & \({}^{\text{b}}\) & \(96\pm 2\) & \({}^{\text{ab}}\) & \(8\pm 5\) & \({}^{\text{ns}}\) & \(3\pm 2\) & \({}^{\text{ns}}\) & \(15\pm 8\) & \({}^{\text{ns}}\) & \(2\pm 1\) & \({}^{\text{ns}}\) \\
**Medium High** & \(92\pm 0\) & \({}^{\text{ab}}\) & \(95\pm 4\) & \({}^{\text{ab}}\) & \(90\pm 4\) & \({}^{\text{a}}\) & \(85\pm 4\) & \({}^{\text{a}}\) & \(2\pm 1\) & \({}^{\text{ns}}\) & \(0\pm 0\) & \({}^{\text{ns}}\) & \(5\pm 4\) & \({}^{\text{ns}}\) \\  & **High** & \(95\pm 0\) & \({}^{\text{a}}\) & \(91\pm 5\) & \({}^{\text{a}}\) & \(93\pm 5\) & \({}^{\text{a}}\) & \(86\pm 5\) & \({}^{\text{ab}}\) & \(89\pm 6\) & \({}^{\text{a}}\) & \(1\pm 1\) & \({}^{\text{ns}}\) & \(1\pm 1\) & \({}^{\text{ns}}\) \\ \hline  & **Low** & \(90\pm 5\) & \({}^{\text{ab}}\) & \(97\pm 2\) & \({}^{\text{ab}}\) & \(100\pm 0\) & \({}^{\text{a}}\) & \(98\pm 3\) & \({}^{\text{b}}\) & \(92\pm 5\) & \({}^{\text{a}}\) & \(93\pm 4\) & \({}^{\text{a}}\) & \(94\pm 5\) & \({}^{\text{a}}\) \\
**4 \({}^{\circ}\)C** & **Medium Low** & \(90\pm 1\) & \({}^{\text{ab}}\) & \(99\pm 1\) & \({}^{\text{b}}\) & \(92\pm 3\) & \({}^{\text{a}}\) & \(89\pm 5\) & \({}^{\text{a}}\) & \(92\pm 1\) & \({}^{\text{a}}\) & \(92\pm 6\) & \({}^{\text{a}}\) \\  & **Medium High** & \(91\pm 3\) & \({}^{\text{ab}}\) & \(93\pm 3\) & \({}^{\text{ab}}\) & \(87\pm 0\) & \({}^{\text{a}}\) & \(83\pm 5\) & \({}^{\text{a}}\) & \(89\pm 4\) & \({}^{\text{a}  
which thiocyanate is the major substrate represent a less-effective way of oxidants production and a substrate-expensive way of use of the LPO-system. Figure 4: KI/KSCN ratio \(<1\). Oxidation levels of \(-\)SH (plain line) and \(-\)NH\({}_{2}\) (dashed line) (\(\mu\)M), total pseudo-halogen concentrations (light-colored bars) (mM), and KI/KSCN ratios (dark-colored bars) (mM) of various doses of (KI + KSCN) after lactoperoxidase oxidoreductase in tap water. Means and s.d. of the two independent experiments are given. Figure 5: KI/KSCN ratio \(=1\). Oxidation levels of \(-\)SH (plain line) and \(-\)NH\({}_{2}\) (dashed line) (\(\mu\)M), and total pseudo-halogen concentrations (light bars) (mM) of various doses of (KI + KSCN) after lactoperoxidase oxidoreductase in tap water. Means and s.d. of the two independent experiments are given. When the same amount of thiocyanate and iodide are added in the media (KI/KSCN ratio = 1; Figure 5), the enzyme is able to produced high doses of oxidants if the total amount of substrate added are high. The SH-dosage is relatively close to the NH\({}_{2}\)-dosage, so that it can be hypothesized that oxidant are mainly represented by iodide-oxidized oxidant. The oxidation of iodide seems to be more effective when both substrates increased. However, the use of equal amount of iodide and thiocyanate are less-effective in oxidants production, especially with regards to the total quantity of substrates added (10.8 mM) that reached about 400 uM oxidant when compared with total substrate of 6.6 mM (5.4 mM KI + 1.2 mM KSCN) and the same amount of 400 uM oxidants produced (Table 2). When more iodide is added relative to thiocyanate (KI/KSCN ratio > 1; Figure 6), the oxidant production curve was bell-shaped, with an optimal ratio around 4.5, and a less favorable ratio above 9 or below 2.5. If the ratio moved closer to 1, the oxidant production decreased, as if the ratio increased above 9. A ratio above 9 means that thiocyanate dropped, and could mean that oxidation of a precise level of thiocyanate is essential for an optimal level of iodide-derived oxidant production.