## 2 Results
### VOC Identification  
To further understand the basis of ABp5's bioactivity, we chemically analyzed the gas phase of the endophyte grown on NPDA agar slant by GC-MS. Table 1 presents the 10 different suggested compounds identified by GC-MS (see Table S1 for additional information). These compounds belonged to the ketone, alcohol, phenol, fatty acid and ester families. Nine of them were commercially available (oxime-, methoxy-phenyl-, was not available).  
\begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline
**Retention** & & & & **Molecular** & & & \\
**Time (Min)** & **Compound \({}^{\star}\)** & **Family** & & **Formula** & & & \\ \hline
6.882 & \multicolumn{1}{c}{Oxime-, methoxy-phenyl-} & Phenol & C\({}_{8}\)H\({}_{9}\)NO\({}_{2}\) & 151.1 & 79.12 & 1,321,307 & 53,113,398 \\
9.488 & \multicolumn{1}{c}{2-Propyl-1-pentanol} & Alcohol & C\({}_{8}\)H\({}_{18}\)O & 130.1 & 85.71 & 1,055,720 & 42,679,237 \\
10.773 & \multicolumn{1}{c}{2-Nonanone} & Ketone & C\({}_{9}\)H\({}_{18}\)O & 142.1 & 82.44 & 2,906,369 & 85,262,293 \\
12.137 & \multicolumn{1}{c}{2-Decanone} & Ketone & C\({}_{10}\)H\({}_{20}\)O & 156.2 & 75.06 & 1,167,692 & 33,491,708 \\
12.383 & \multicolumn{1}{c}{8-Nonenoic acid} & Fatty acid & C\({}_{9}\)H\({}_{16}\)O\({}_{2}\) & 156.1 & 82.06 & 755,023 & 28,399,821 \\
14.513 & \multicolumn{1}{c}{2-Undecanone} & Ketone & C\({}_{11}\)H\({}_{22}\)O & 170.2 & 91.03 & 3,424,025 & 79,041,922 \\
14.623 & \multicolumn{1}{c}{2-Undecanol} & Alcohol & C\({}_{11}\)H\({}_{24}\)O & 172.2 & 83.82 & 1,391,479 & 44,357,455 \\
15.716 & \multicolumn{1}{c}{2-Dodecanone} & Ketone & C\({}_{12}\)H\({}_{24}\)O & 184.2 & 73.23 & 1,460,936 & 39,991,523 \\
17.23 & \multicolumn{1}{c}{2-Tridecanone} & Ketone & C\({}_{13}\)H\({}_{26}\)O & 198.2 & 88.75 & 1,502,874 & 36,978,277 \\
19.379 & \multicolumn{1}{c}{2,2,4-Trimethyl-1,3-pentanediol} & \multicolumn{1}{c}{Ester} & C\({}_{16}\)H\({}_{30}\)O\({}_{4}\) & 286.2 & 83.7 & 2,495,851 & 73,829,637 \\ \hline \hline \end{tabular} \({}^{\star}\) Identified according to NIST Mass Spectral Library.  
\end{table}
Table 1: Volatiles secreted by isolate ABp5 and identified by GC-MS through a comparison of their retention indices with published values (NIST 14).  
Figure 1: In vitro bioactivity assays of _K. flavus_ isolate ABp5 against the aquaculture pathogen _Saprolegnia parasitic_. ABp5 was grown in the middle of an NPDA plate for a week (A + B, right plates) before a plug of solid medium harboring live _S. parasitic_ mycelia was added to the plates. Control plates were inoculated with _S. parasitic_ in the absence of ABp5 (A + B, left plates). **(A)** A two-compartment petri plate used for the bioactive volatile emission assay. The divider prevents any direct contact of ABp5 and its secreted secondary metabolites with the pathogen, allowing only volatile movement in the headspace between the compartments. **(B)** One-compartment petri plate. In this assay, ABp5 can inhibit the pathogen through both direct and indirect contact with secondary metabolites (secreted or emitted through the agar or the headspace, respectively). In both panels A and B, _S. parasitic_ was fully inhibited by ABp5. **(C)** Pathogen viability assay. _S. parasitic_ from both assays (direct and headspace exposure) were transferred to a plate with new medium plate in the absence of ABp5. There was no growth of pathogens from either assay (shown for the headspace experiment only); a plug from the control plate was viable and grew as expected (right side of the plate).