Sustainable strategy for the enhancement of hazardous aromatic amine degradation using lipopeptide biosurfactant isolated from Brevibacterium casei

Highlights: • This is the first report on hazardous 4-Aminobiphenyl (4-ABP) degradation using Brevibacterium casei. • Lipopeptide exhibited best emulsification (66 ± 0.65%), surface activity (29.6 m Nm⁻¹) and oil spreading (2.6 ± 0.25 cm). • Biosurfactant enhanced the bacteria for degradation of 4-ABP up to 9 mgL⁻¹. • GC-MS process revealed the presence of metabolite such as 5-Amino-2-methoxy phenol. The application of biosurfactants for the degradation of various toxic compounds has received much attention among researchers worldwide. A stimulated degrading method was carried out in this research to determine the efficiency of surfactant on the biodegradation of aromatic amine 4-Aminobiphenyl (4-ABP). The biosurfactant mediated process is an alternative strategy for chemical surfactants because chemical surfactants are toxic and nonbiodegradable. The bacterium was isolated through the enrichment process and identified using 16S rRNA sequencing method. The molecular characterization showed that the isolate belongs to Brevibacterium casei-4AB. Biosurfactant produced in this study was examined through screening activities like oil spreading, emulsification activity and surface tension measurement. Instrumental characterization like Fourier Transform Infrared Spectrophotometer (FT-IR) results suggested that there is a presence of NH group, aliphatic hydrocarbons, ester groups, amide and alkenes and further Gas chromatography- Mass Spectrometry (GC-MS) results confirmed the presence of fatty acids such as Hexadecanoic and Octadecadienoic acid which showed that the produced surfactant is lipopeptide. Protein content and lipid content in the biosurfactant was found to be 18 ± 0.8% and 30 ± 0.1%. The degraded metabolites of 4-ABP were analyzed through the GC-MS process which revealed the presence of metabolites such as 5-Amino-2-methoxy phenol.