In Vitro Evaluation of the Biosurfactant Produced by Serratia ureilytica UTS with Antifungal and Nematicidal Activity Against Nacobbus aberrans

In the present study, the nematicidal and fungicidal activity of the biosurfactant (BS) produced by the strain Serratia ureilytica UTS was evaluated. The highest mortality of J2 juveniles of the nematode Nacobbus aberrans was 92.3% at a concentration of 30 mg/mL. Among the phytopathogenic fungi, the concentration of 1.0% of the crude extract of the biosurfactant was the one that obtained the highest percentage inhibition against the phytopathogens Fusarium oxysporum 72.2%, Fusarium sp., 80.2% and Alternaria solani 100% at 168 h of incubation. Analysis of the BS by GC-MS revealed the presence of the three amino acids alanine, homocystine and valine in its composition. As well as the presence of fatty acids: stearic acid, lauric acid and palmitic acid. With nuclear magnetic resonance (NMR) and mass spectrophotometry (MS) analysis, the crude extract was found to have the structure of a quaternary ammonium salt derived from stearic fatty acid, which is a component of the biosurfactant. Based on this evidence, it is suggested that the BS produced by S. ureilytica has a lipopeptide-like chemical structure and possesses nematicidal and fungicidal activity, and is therefore proposed for potential use and application as a biopesticide for the benefit of regenerative and sustainable agriculture.