## 4 Discussion
The mechanisms by which bacterial VOCs alter plant pathogen growth and virulence represent an area that is attracting increasing interest [45; 46; 47]. In this regard, some studies have assessed how VOCs can also regulate bacterial virulence on _Pectobacterium_ spp. during the course of pathogenesis [48]. In this context, the 2,3-butanediol pathway has been detected in _P. carootovorum_ subsp. _carootovorum_, showing high gene expression (_budAB_ operon) during pathogenesis in potato tubers, and _budB_ gene disruption has been shown to lead to significantly less macerated tissue, but not growth inhibition [48]. Interestingly, the _budB_ gene encoding an \(\alpha\)-acetolate synthase and participating in the condensation of two molecules of pyruvate into \(\alpha\)-acetolate, which are then converted into acetoin, hasbeen associated with the alkalization of the growth culture medium, which favors pectate lyase activity in different microorganisms causing plant tissue disease [48]. Aligning with these reports, our results regarding treatment T12 encourage similar interpretations; in this treatment, acetoin was added and yielded marked soft rot symptoms, similar to the positive control treatment T2. However, regarding treatment T10, it remains to be explored as a mixture of acetoin and 2,5-dimethyl-pyrazine at lower volume concentrations can reduce soft rot symptoms. These combined results suggest that a fluctuation in the relative concentrations of VOCs during competitive bacterial colonization affects pathogenic responses. A possible explanation of these results offered previously is that the diffusible quorum-sensing signal molecule N-acyl-homoserine lactone (AHL) could be affected by pH during the synthesis of acetoin, because it is hydrolyzed into an inactive form when above pH 6.8, thus affecting the regulation of key virulence genes' expression [48; 49]. Another possibility is that 2,5-dimethyl-pyrazine, which has been previously reported in other bacterial genera, and which has antifungal and antibacterial properties, could have metabolic effects at lower concentrations but bactericidal effects at higher concentrations [47]. On the other hand, although other individual VOCs identified in the lag growth phase were not tested, organic compounds such as cyclododecane could represent an area of interest, because this is a chemical compound with high toxicity that is persistent in the environment and has lower biodegradability [50]. Given its lipophilic nature, cyclododecane is easily absorbed and bioaccumulated in the fatty tissues of living organisms, and its growth toxicity in relation to bacteria has been evaluated [50]. Benzaldehyde is another chemical compound that is detected in the lag growth phase of _K. covanii_ Cp1; it is considered to be environmentally safe because it is highly biodegradable and presents bactericidal effects causing alterations in the cell membrane [51]. Therefore, the ways in which the properties of VOCs in combination or alone promote growth and pathogenic alterations in _P. aroidearum_ SM2 require additional research. Although some common chemical classes of VOCs detected in _K. covanii_ Cp1 have been identified in phylogenetically different bacterial species using single or mixed bacterial cultures [46; 47], the fact that similar metabolic pathways are genetically conserved to produce VOCs suggests that similar physiological responses with different effects on competitive colonization can converge to enable efficient communication and antagonistic interactions between bacterial communities in a specific ecological niche. In this sense, the use of VOCs to enact the biocontrol of pathogenic microorganisms or to elicit different physiological plant responses must be pursued carefully to avoid undesired responses. For example, 2,3-butanediol can have negative impacts on bacterial growth, biofilm formation, and motility, but it can also promote pathogen resistance in plants [46; 47].