## 3 Discussion
putida_, SJ04 and SJ46, grown under different salt stress conditions showed that they emit similar compounds. In the headspace of SJ46, considering only the compounds not present in the control profiles, there were three other compounds identified, belonging to hydrocarbon and alcohol classes, with similar VOCs being found in the SJ04 emission with the addition of 1-(N-phenylcarbamoyl)-2-morpholinocyclohexene and tridecane. In particular, the hydrocarbon decane identified in the SJ46 and SJ04 mVOCs was previously detected in _Pseudomonas_ strain blends but did not display specific biocontrol activity against the plant pathogenic fungus _Sclerotinia scleroorum_[78]. In addition, in another study, it was found in the headspace of _B. subtilis_ GB03, _B. subtilis_ 168, and _B. amyloliquefaciens_ IN937a [79], with effects of systemic resistance induction (ISR)having been described in _Arabidopsis_. Tridecane was also identified in _B. pumilus_ ES4 emissions, and _Azospirillum brasilense_ Cd showed a growth-promoting effect on _Chlorella sorokiniana_[80]. This was also identified in volatiles of _Serratia_ sp. [81] and _Paenibacillus_ sp. P4 [82]. Both tridecane and tetradecane were detected in _P. simiae_ and were found to increase seed germination and higher fresh weight in soybean plants [65]. Octanol was identified in the _B. subtilis_ CF-3 VOCs emitted in the blend with 2,4-di-tert-butylphenol and benzothiazole, with these compounds showing significant positive correlations with the rates of _Monilinia fructicola_ and _Colletotrichum gloeosporoides_ inhibition [83]. Finally, octanol has been demonstrated to completely inhibit spore germination of _Penicillium camemberti_ at low concentrations [84]. The VOC profiles of SJ04 and SJ46 were found to be similar, possibly because both rhizobacteria are closely related to each other phenotypically and genotypically, so they were presumably subjected to similar selective pressures since they were obtained from the same place of origin [51; 85; 86]. In the present study, we only used Hoagland, which is a minimum culture media. In contrast, [PERSON] et al. [87] examined the mVOC emissions of six bacteria from the genera _Bacillus_, _Serratia_ and _Pseudomonas_ in three different media types. These authors found that Murashige and Skoog (M + S) was responsible for a smaller number of mVCCs detected in comparison with methyl red-Voges Proskeur (MR-VP) and tryptic soy broth (TSB), suggesting that these results may have been attributed to the carbon-rich composition of the media. It is also important to mention that the VOC profile emissions detected are conditioned by the different techniques used, with the identification of VOCs being highly dependent on the SPME fiber or the organic solvent used to collect compounds by dynamic headspace. In our study, we analyzed the headspace only by the DVB/CAR/PDMS SPME fiber. However, some studies have revealed some differences in mVCCs when analyzed by three different kinds of extraction fibers, such as 85 \(\upmu\)m polyacrylate (PA), 100 \(\upmu\)m PDMS, and 7 \(\upmu\)m PDMS [83]. In fact, the fiber coating plays a crucial role in adsorbing VOCs of a specific chemical nature, based on the polarity and size [28]. It has been shown that some substances are high in content but their bioactive effect is not obvious, while other substances are low in content, but their effect can be very significant [88]. Even when investigators have evaluated the promoting activity using standards, they have often not observed the same level of response in comparison with the whole VOC blend [53]. In addition, the presence of the main active compounds with bioactive effects on the VOC profile does not always ensure the same response or effect on the receiver organism. [PERSON] et al. [77] reported that the VOC emissions of _Pseudomonas_ isolated from avocado rhizobacteria did not reduce the mycelium growth of _Phyophthora cinnamomi_, although dimethyl disulfide (DMDS) and dimethyl trisulfide (DMTs) were identified in the volatile profile.