Table 1.
GC—MS headspace SPME identification of relevant VOCs produced by P. polymyxa Sb3-1 and V. longisporum ELV43 grown for 3 or 6 days in presence of each other volatiles.
| RT (min) | Predicted compounda | Regulationb | Predicted function |
|---|---|---|---|
| VOCs PRODUCED BY Sb3-1 AFTER BOTH 3 AND 6 DAYS GROWTH IN PRESENCE OF V. longisporum VOCs | |||
| 8.521 | 1,3-Dioxolane, 2,2,4,5-tetramethyl-, trans-* | ↑986%** | N.a. |
| 12.238 | Pentafluoropropionic acid, hexyl ester* | ↓47,6%** | N.a. |
| 19.248 | 2-Nonanone* | – | Antibacterial (Schulz and Dickschat, 2007) |
| 20.893 | 2-Decanone* | – | N.a. |
| 20.980 | 2-Decanol* | – | N.a. |
| VOCs PRODUCED BY Sb3-1 ONLY AFTER 3 DAYS OF CO-INCUBATION WITH V. longisporum VOCs | |||
| 5.25 | 2,3- Butanedione* | – | PGP, antibacterial (Farag et al., 2006; Lee et al., 2012) |
| 5.8 | 2-Methyl-1-Propanol* | – | Antifungal (Stotzky et al., 1976) |
| 6.438 | 1-Butanol* | – | Antibacterial (Létoffé et al., 2014) |
| 7.497 | 3-Hydroxy-2-butanone* | – | PGP, ISR (Ryu et al., 2003) |
| 8.239 | 2-Methyl-1-butanol* | – | Antifungal (Raza et al., 2015) |
| 8.605 | 3-Methyl-2-pentanone* | – | N.a. |
| 12.501 | Isoamyl Acetate | ↓56% | Antimicrobial (Ando et al., 2015) |
| 13.335 | 2-Heptanol* | – | Antimicrobial (Orhan et al., 2012) |
| 19.621 | Decane, 2,6,7 trimethyl* | – | N.a. |
| 20.773 | Hexadecanal | – | Antifungal (Raza et al., 2015) |
| 21.090 | Decyl trifluoroacetate* | – | N.a. |
| 23.091 | Durenol | ↓34.1%** | Possibly antimicrobial (Al Nomaani et al., 2013) |
| 23.232 | 2-(2-Methylpropyl)-3- (1-methylethyl) pyrazine | – | Antimicrobial (Aichner et al., 2012) |
| 26.556 | Spathulenol | ↓44%** | Plant metabolite (Pacciaroni et al., 2008) |
| 24.686 | 2-Dodecanal* | – | N.a. |
| VOCs PRODUCED BY Sb3-1 ONLY AFTER 6 DAYS GROWTH IN PRESENCE OF V. longisporum VOCs | |||
| 10.25 | 2-Hydroxy-3-pentanone* | – | N.a. |
| 12.25 | Pentaflouropropionic acid, hexyl ester* | – | N.a. |
| 15.75 | 2- Isopropylpyrazine | – | Antimicrobial (Aichner et al., 2012) |
| 16.6 | 3(2H)-Thiononanoe | ↑51.5% | N.a. |
| 17.79 | 1,2-Butanediol, 1-phenyl | – | N.a. |
| 18.74 | p-cresol* | – | toxic for eukaryotic cells (Andriamihaja et al., 2015) |
| 23.13 | 2- N-(2-methylpropyl) Benzothiazolamine | ↓38.3% | N.a. |
| 23.23 | 2-(2-Methylpropyl-)-3-(1-methylethyl) pyrazine | – | Antimicrobial (Aichner et al., 2012) |
| VOCs PRODUCED BY VL43 AFTER BOTH 3 AND 6 DAYS GROWTH IN PRESENCE OF P. polymyxa Sb3-1 VOCs | |||
| 5.80 | Isobutanol* | – | Antifungal (Stotzky et al., 1976) |
| 19.90 | 2-phenylethanol* | – | Antimicrobial (Liu and Zhang, 2015) |
| VOCs PRODUCED ONLY AFTER 3 DAYS OF CO-INCUBATION WITH P. polymyxa Sb3-1 VOCs | |||
| 7.65 | Acetoin* | – | PGP, ISR (Ryu et al., 2003) |
| 13.34 | 2-(4-Cyclohexyl-butanoylamino) -3-chloro-1,4-naphthoquinone | ↑100%** | Putatively antifungal (Sasaki et al., 2002) |
| 17.792 | Bicyclo (2.2.1)-hepta-2,5-dien-7-ol; or 7-Hydroxynorbornadiene | ↑100%** | N.a. |
| VOCs PRODUCED ONLY AFTER 6 DAYS GROWTH IN PRESENCE OF P. polymyxa Sb3-1 VOCs | |||
| 6.44 | 1-Butanol* | ↑53.4% | Antimicrobial (Létoffé et al., 2014) |
| 8.10 | Isoamyl alcohol* | – | Antimicrobial (Ando et al., 2015) |
| 9.23 | 1,2,4- Benzenetricarboxylic acid, 1,2 dimethyl ester | ↑100%** | N.a. |
| 17.793 | Nα, Nω-Dicarbobenzoxy-L-arginine | ↑100%** | N.a. |
| 18.08 | 2-Nonanone* | – | Antifungal (Raza et al., 2015) |
| 19.98 | 3-Phenyl-5-(benzylthio)isoxazole | ↑17.9% | N.a. |
| 25.84 | 5,6-Decadien-3-yne,5,7-diethyl | ↑20% | N.a. |
The selection of substances included in the Table was performed as followed: (1) only substances with match index with the NIST MS Search 2.2 included in the Software-Package of the NIST 2014 database over 500 were considered; (2) only the substances that were either verified using covats index [ < 15; labeled with asterisks (
)] or showed an up- or down-regulation due to the presence of the VOCs of the other microorganism were included in the Table. The predicted functions of the substances are highlighted in color as follows: the substances with predicted antimicrobial activity are shown in light red, substances with putatively plant growth regulating functions are light green and unknown substances are highlighted in gray.
Regulation in presence of microorganism's VOCs (%). Arrow down (↓) indicates the significant down-regulation of the substance, while the arrow up (↑) represents the significant up-regulation of a substance. A minus sign (“–”) denotes that no significant up- or downregulation of the substance in the presence of the VOCs was detected. The VOCs that were identified by Raza et al. (2015) as produced by P. polymyxa WR-2 are highlighted in bold.
The double asterisk(
)denotes values that were significantly different from the non-treated control group values (P < 0.05) defined using pairwise t-test or non-parametric Mann–Whitney U-test, depending on the distribution of the samples.