# Effects of Growth Parameters on the Analysis of _Aspergillus flavus_ Volatile Metabolites
## 3 Results and Discussion
### Effect of the Growth Substrates on MVOCs' Production
\begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline \multirow{2}{*}{**No. **} & \multirow{2}{*}{**MVOC a**} & \multirow{2}{*}{**Chemical**} & \multirow{2}{*}{**R.T. (min)**} & \multicolumn{6}{c}{**Media (Peak Area \(\times\) 10b)**} \\ \cline{5-8}  & & & **Classes** & & **CDA** & **CSA** & **CDL** & **MEA** & **CMA** \\ \hline \multirow{2}{*}{101} & \multirow{2}{*}{Bicycld[4.4,0]dec-1-ene, 2-isopropyl-5-methyl-9-methylbenzene} & \multirow{2}{*}{sesquiiterpene} & 45.110 &  
A total of 132 MVOCs are detected in fungal cultures grown on all substrates. Forty one of the MVOCs were produced by the fungus in at least 4 out of 5 growth media substrates. Ten MVOCs were produced on all growth media, including ethanol (1), 2-methyl-furan (18), toluene (10), dodecane (54), decanal (67), (Z)-3-Hexadecene (84) and some sesquiterpenes (trans-\(\alpha\)-bergamotene (82), (\(-\))-aristolene (88), \(\beta\)-elemene (89) and valencene (104). These common fungal MVOCs have the potential to be considered as a group of indicators of fungal growth. Different MVOC profiles are produced when the fungus is grown on different media. This difference can be seen when MVOCs are divided into different chemical classes (alcohols, aldehydes, alkanes, alkenes, esters, ethers, furans, hydrocarbons, aromatic hydrocarbons, ketones, organic acids and sesquiterpenes), as shown in Figure 3. The 132 MVOCs were grouped by chemical class and their raw peak areas summed for Figure 3. MANOVA was performed to test whether there are significant differences among the total quantities of MVOCs in each chemicals' class across the five growth media. Figure 3 illustrates that the MVOCs' production in CDA media has larger amounts of furans than the other media. Among these growth media, the fungi growth on the CDL media produces the largest amount of aldehydes, a combination of ether and esters, aromatic hydrocarbons and alkenes. CDL and CDA have an identical list of ingredients, except for the addition of 15 g of agar to the CDA media, which helps to produce a gel-like media. The quantities of MVOCs produced by the fungi growth  
Figure 3: Comparison of the amount of volatile metabolites (sum of peak area with SD (six replicates)) emitted by _A. flavus_ 5-3B on growth media CDA, CSA, CDL, MEA and CMA. Different letters above the bars indicate significant differences (MANOVA, \(p<0.05\)). The data with the highest total ion current (TIC) for each chemical class starts with label a. The TIC of each medium shows no significant difference in the alkane group. (**A**): Chemical classes of aldehydes, alkanes, ethers and esters, ketones and organic acids; (**B**): Chemical classes of alcohols, alkenes, furans, aromatic hydrocarbons; (**C**): Medium type. on the liquid media (CDL) are much greater than those grown on the agar medium (CDA) for all chemical classes, expect the furans. Interestingly, both CDL and CDA produced significantly more sesquiterpenes than the other growth media (Figure 3C). One possible explanation is the addition of L-asparagine, which has been shown to enhance the production of sesquiterpenes and aflat [54]. MVOCs' production is clearly affected by growth media.