## 5 Conclusions  
This work identified _A. pullulans_ as a potential candidate in conferring olive tree protection against anthracose. This yeast was effective in reducing the development of anthracose, mycelial growth, sporulation and germination of _C. acutatum_ either in in vitro or in vivo assays. Its features were ascribed to the production of volatile organic compounds, with _Z_-3-hexen-1-ol, benzyl alcohol and nonanal being the most promising inhibitory compounds. However, their effectiveness against _C. acutatum_ should be further evaluated under in vitro conditions and in the field. The contribution of other antimicrobial compounds, particularly diffusible compounds, to the inhibitory effect displayed by _A. pullulans_ against _C. acutatum_ cannot be disregarded and should be further deepened. Our results also suggest that some VOCs positively associated with and differently produced in olives inoculated solely with _C. acutatum_ are likely to play a role in the pathogenicity and/or development of anthracose. These findings may provide opportunities to develop new tools for integrated management of anthracose disease, through the exploitation of _A. pullulans_ or VOCs. **Supplementary Materials:** The following supporting information can be downloaded at: [[https://www.mdpi.com/article/10.3390/microorganisms10030571/s1](https://www.mdpi.com/article/10.3390/microorganisms10030571/s1)]([https://www.mdpi.com/article/10.3390/microorganisms10030571/s1](https://www.mdpi.com/article/10.3390/microorganisms10030571/s1)), Figure S1: Relative abundance (expressed in chromatographic area) of volatile organic compounds per chemical class identified in olives inoculated with _Aureobasidium pullulans_ and _Colletotrichum acutatum_ (_A. pullulans_ + _C. acutatum_), or solely with _A. pullulans_, _C. acutatum_ or Tween (controls); Figure S2: Heatmap visualization of volatile compounds identified in olives (a) inoculated with _Aureobasidium pullulans_ and _Colletotrichum acutatum_ (Ap + Ca), or solely with _A. pullulans_ (Ap), _C. acutatum_ (Ca) or Tween (controls) (b), after 2, 8 and 16 days of pathogen inoculation. The color intensity (blue to red) refers to the compound abundance in each sample; Figure S3: Log2-fold changes in the abundance of individual volatile organic compounds in olives inoculated with _Aureobasidium pullulans_ and _Colletotrichum acutatum_ (Ap + Ca), _A. pullulans_ (Ap) or _C. acutatum_ (Ca) relative to olives inoculated with Tween (control); Figure S4: Log2-fold changes in the abundance of individual volatile organic compounds in olives after 2, 8 and 16 days of fungi inoculation relative to olives inoculated with Tween (control); Table S1: Volatile compounds detected in this study: retention time (RT). The Kovats retention index (RI), and selected ions used as m/z identifiers (QI) [54]; Table S2: Relative importance of the treatment (olives inoculated with _Colletotrichum acutatum_, _Aureobasidium pullulans_ or _A. pullulans_ + _C. acutatum_) and time of microbial interaction (2, 8 and 16 days) to the volatile composition, as revealed by permutational multivariate analysis of variance (PERMANOVA). **Author Contributions:** Conceptualization, J.A.P. and P.B. ; data curation, Y.S., N.R. and P.B. ; formal analysis, Y.S., I.R. and P.B. ; funding acquisition, P.B. ; investigation, Y.S., T.L. and K.S. ; methodology, N.R., J.A.P. and P.B. ; resources, J.A.P. and P.B. ; supervision, J.A.P. and P.B. ; writing--original draft, Y.S. ; writing--review and editing, N.R., J.A.P. and P.B. All authors have read and agreed to the published version of the manuscript. **Funding:** This research was funded by FEDER funds through COMPETE (Operational Programme for Competitiveness Factors) and by the Foundation for Science and Technology (FCT, Portugal) within the POCI-01-0145-FEDER-031133 (MicOlives, PTDC/ASP-PLA/31133/2017) project, as well as the Mountain Research Center--CIMO (UIDB/00690/2020). **Institutional Review Board Statement:** Not applicable. **Informed Consent Statement:** Not applicable.