## 3 Discussion
Antifungal activity of VOCs has been reported to be associated with the functional group [41], and it is dependent on \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Disease Incidence** & **3 d** & **5 d** & **10 d** & **15 d** \\ \hline Control & 12.50\% & 20.83\% & 54.17\% & 100.00\% \\ BCN2 & 0.00\% & 4.17\% & 20.83\% & 87.50\% \\ BCN10 & 0.00\% & 5.77\% & 22.34\% & 89.08\% \\ BCN2+BCN10 & 0.00\% & 3.56\% & 20.19\% & 86.95\% \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Inhibitory effect of volatile organic compounds produced by two _Bacillus_ strains in the natural decay of loquat fruit. the hydrophobicity of the solute, which affects the depth of penetration into the bilayer, and the induced changes in the physic-chemical properties [40]. It is well known that the effect of a lipophilic compound on the integrity of a membrane depends on its location in the membrane, where it has been accumulated, resulting in lower membrane integrity and an increase in the proton passive flux-across the membrane. This could be the case of carbon disulfide that dramatically suppressed the growth of pathogens in loquat fruit. Among these VOCs, fatty acids with short chains are highly active compounds against fungi, probably due to their higher solubility in water [42]. In this study, acetic acid (a food additive with broad-spectrum antibiosis activity) and 2-methylpropanoic acid (a common antibacterial component in many plant essential oils) in _Bacillus_ VOCs probably exhibit obvious effective antifungal activity. In contrast to fatty acids, alcohols are not selectively adsorbed and are mainly accumulated in the cell membrane, determining membrane functions inhibition, which in turn, is responsible for their antimicrobial activity [43]. In particular, 3-methylbutan-1-ol may be the effective compound in bacterial VOCs against fungal growth. Because some alcohols, such as 3-methylbutan-1-ol (also known as isoamyl alcohol), can be adsorbed on the spores' surface and therefore adhere to it for a long time, resulting in spore germination inhibition [44]. Some articles reported antifungal activity analyses of selected molecules produced by single _Bacillus_ species [14; 38; 45; 46], and the activity of ketones was considered to be negatively correlated with the number of the carbon atoms, and thus nonan-2-one and decan-2-one, in particular, showed strong inhibition activity [14]. Other volatile molecules produced by _Bacillus_ species have been tested as single compounds towards the fungal growth of other species, and the results showed significant antifungal activity. For example, aldehydes like o-anysaldehyde, nonanal, and n-decanal, could reportedly inhibit germ tube formation of _Alternaria alternate_[17], or mycelia growth of _B. cinerea_ and _S. sclerootomy_[45; 46]. Furthermore, alcohols like hexan-1-ol, 2-ethylcyclohexanol, benzothiazole and dimethyl trisulphide exerted high fungicidal activity against _S. sclerootomy_[46]. In addition, 2-methylpirazyne and \(\beta\)-benzeneethanamine showed antifungal effect against _C. gloesporoides_[15]. Inhibitory effects of VOCs produced by the two _Bacillus_ strains _B. methyldotroplicus_ BCN2 and _B. thuringiensis_ BCN10 on natural decay of loquat fruits were strongly manifested. The difference of disease incidence between experimental groups and control groups demonstrated that the VOCs emitted by both BCN2 and BCN10 could put off the decay of loquat till the fifth day, which was three days later than the control groups and enabled more loquat to keep fresh for ten days significantly. Future research will be directed toward designing agriculturally practical ways to efficiently use antifungal volatiles to reduce fruit decay under storage conditions. The two _Bacillus_ strains are complementary in the role of antagonism against the pathogens. Mixed cultures of the microbial antagonists appear to provide better control of postharvest diseases over individual cultures.