## 3 Results
### Antibacterial Activity of Mango By-Products  
#### 3.2.1 Acetic Acid Bacteria  
A preliminary and exploratory screening of the antibacterial activity of mango by-products against three AAB species (_A. malorum_, _A. tropicalis_ and _G. japonicus_) was performed using agar diffusion assay. All extracts (from peel and seed) had an inhibition effect against the tested bacteria. Likewise, the extraction process and the cultivar affected the bioactive compounds extracted and therefore their antibacterial activity. Peel extracts obtained by process B showed higher antibacterial activity in the agar diffusion assay (1.5 times on average) than extracts obtained by process A. On the other hand, the peel and seed extracts from Gomera-3 and Sensation cultivars showed higher antibacterial activity than extracts obtained from the Keitt cultivar. For a quantitative analysis of the antibacterial activity, the MIC and the MBC were determined against six species of AAB (thirteen genotypes typified by ERIC-PCR and (GTG)\({}_{5}\)-PCR. In this case, all the extracts were diluted to a final concentration between 1.7 and 400 mg GAE/mL. The serial dilution assays confirmed the antibacterial properties of the extracts, with the exception of _G. saccharivonus_ that was resistant at the maximum concentration tested (400 mg GAE/mL). A wide range of MIC and MBC values was observed among the different bacterial species, with MICs from 1.7 mg GAE/mL in _A. cerevisiae_ to 200 mg GAE/mL in _A. tropicalis_ and _G. japonicus_, and MBCs from 17 mg GAE/mL to 400 mg GAE/mL in the same species mentioned above (Table 1). Taking into account the MIC values in the peel extracts, two arbitrary groups can be defined: Group I, species with MICs \(\leq\) 50 mg GAE/mL (_A. cerevisiae_, _A. pasteurianus_ and _A. malorum_), and Group II, species with MICs \(\geq\) 50 mg GAE/mL (_A. tropicalis_, _G. japonicus_ and _G. saccharivorans_) (Table 1). In no case extracts B showed higher MICs than extracts A. Peel extracts obtained by extraction A showed higher MIC values than extracts obtained by extraction B in each bacterial species tested in at least in one of the cultivars. In the Gomera-3 cultivar, MICs from extracts A were higher than extracts B in 66.6% of the genotypes (Ac2, Ac3, Ac5, Am17, Am25, Am26, Ap16 and Gj2), while in the Keitt cultivar,MICs from extracts A were higher than extracts B in 58.3% of the genotypes (Ac2, Ac3, At1, At2, Gj1, Gj2 and Gj3). In the extracts obtained by process A, _A. cerevisiae_ and _A. malorum_ showed no differences between cultivars; however, _A. pasteurianus_ showed a lower MIC value with the extract obtained from cultivar Keitt, and _A. tropicalis_ with those from Gomera-3. Elsewhere, the highest MIC values in _G. japonicus_ were observed in the Keitt cultivar. In the case of extracts obtained by process B, the Sensation cultivar showed higher MICs than the other cultivars with _A. cerevisiae_ (Ac3), _A. pasteurianus_ (Ap16) and _A. tropicalis_ (At1, At2) (Table 1), while the Gomera-3 cultivar showed the highest MICs with _G. japonicus_ (Gj1, Gj3) and the lowest MICs with _A. cerevisiae_ (Ac5), _A. pasteurianus_ (Ap16) and _A. malorum_ (Am17, Am25, Am26). In seed extracts, the results were variable, being able to highlight the greater MIC values in _A. malorum_ and _A. tropicalis_ with the Keitt cultivar, and the equality of the results among cultivars in the _G. japonicus_ assays (Table 1). In addition, it is important to note the differences between the MIC data of the peel and seed extracts on the different bacterial species and cultivars. For example, in _A. cerevisiae_, the MICs of the seed extracts of the Sensation and Keitt cultivars showed higher values than in the peel extracts; however, in _A. pasteurianus_ (Ap16), the relationship was the opposite (MICs of peel extracts were higher than seed extracts). Likewise, in the Sensation cultivar, the MICs of the seed extracts were lower than the peel extracts. The MBC assay was performed to confirm cell death in the MIC test.