Ochrosin, a new biosurfactant produced by halophilic Ochrobactrum sp. strain BS-206 (MTCC 5720): Purification, characterization and its biological evaluation

• Ochrobactrum sp. strain BS-206 produced a novel biosurfactant.
• Biosurfactant was structurally elucidated as 4-dimethylaminobenzaldehyde.
• High antimicrobial susceptibility towards both bacterial and Candida strains.
• Ochrosin bactericidal action generated ROS and depleted NADH levels.
• Ochrosin exhibited both insecticidal and antifeedant activities.

A new bioactive molecule characterized as 4-dimethylaminobenzaldehyde (designated as Ochrosin) was isolated from a halophilic Ochrobactrum sp. strain BS-206 (MTCC 5720). Ochrosin exhibited good antimicrobial activity against both Gram-positive and Gram-negative bacteria and different Candida strains with minimum inhibitory concentration (MIC) values ranging from 4.68 to 150 μg mL−1. It also exhibited anti-adhesive activity against various bacterial pathogens. Ochrosin caused an increase in the reactive oxygen species (ROS) levels to 32.4% and 28% and increased the NAD+/NADH ratio by 2.61 and 2.26 in S. aureus and E. coli, respectively. Ochrosin appears to interfere with ergosterol biosynthetic pathway in different Candida strains as it reduced the ergosterol content. Ochrosin showed insecticidal activity against three major stored-product grain pests like Tribolium castaneum, Callosobruchus chinensis and Sitophilus oryzae with LC50 values of 7.3, 8.9 and 7.6 μg cc−1, respectively. The anti-feedant index (ED50) values observed were 1.07 and 1.35 μg cm−2 of leaf area against Achaea janata and Spodoptera litura, respectively. This is the first report on Ochrosin, a multifunctional biosurfactant, produced by Ochrobactrum sp. BS-206 exhibiting promising antimicrobial, anti-adhesive, anti-feedant and insecticidal activities.