Abstract

The production and characterization of lipopeptide biosurfactant obtained from a novel bacterial strain Bacillus amyloliquefaciens C11 isolated from a biopurification system, to enhance the solubility of three pesticides of environmental concern was investigated. Biosurfactant production by B. amyloliquefaciens C11 was evaluated in a 2-L reactor and characterized by chromatographic and spectroscopic methods. Biosurfactant production was associated with bacterial growth and glucose consumption. The produced biosurfactant decreased the surface tension of water from 72 to 28 mN m-1 at 24 h of incubation, with critical micelle concentration (CMC) of 51.5 mg L-1. The polymerase chain reaction for determining the presence of srfAA gene in B. amyloliquefaciens C11 was carried out. The strain exhibited the presence of srfAA gene with amplification at 201 bp, which is specific to surfactin homologues. The production of surfactin was corroborated by high performance liquid chromatography (HPLC) and matrix-assisted laser desorption/ionization time-of flight mass spectrometry (MALDI-TOF-MS) analyses. The HPLC analysis showed six isoforms of surfactin, being the isoform D found in mayor percentage (41%). Thermal gravimetric analysis (TGA) revealed the thermostability of the biosurfactant. The obtained biosurfactant maintained its properties during exposure to temperatures in range of 30-80 degrees C and pH values in range of 5-9. The surfactin produced by B. amyloliquefaciens C11 increased the solubility in water of chlorpyrifos, iprodione and atrazine by 7.5-fold, 1.3-fold, and 1.4-fold, respectively. Our results show that the biosurfactant produced by B. amyloliquefaciens C11 improves the bioavailability of pesticides and consequently could improves the efficiency of bioremediation processes.