Journal de la technologie microbienne et biochimique

Abstrait

Screening of Bio-Surfactant Production Ability among Organic Pollutants Degrading Isolates Collected From Egyptian Environment

Mariam Hassan, Tamer Essam, Aymen S Yassin and Aisha Salama

A total of ten bacterial isolates were screened for their biodegradation, metabolic versatility and biosurfactants production using various organic pollutants. The biosurfactants production ability was mainly assessed by oil spread test (OST) and/or emulsification assay (EA). Although initial biosurfactants screening was conducted using paraffin oil, the application of vegetable oils, particularly coconut oil, was always accompanied with the highest yield of biosurfactants production,. Biochemical and molecular identification of the ten isolates revealed that they belong to three genera; Klebsiella (6), Pseudomonas (3) and Citrobacter (1). Interestingly, four isolates (M2H2 1, M2H2 3, M2H2 8 and M2H2 14), showed the highest biosurfactants production and therefore were further assessed using mixed carbon source (coconut oil in combination with one organic pollutant (phenol or cyclohexanol)). The addition of the coconut oil was essential for increased production of biosurfactant, while the use of organic pollutant as a sole carbon source was always accompanied with lower productivity. Isolates (M2H2 1 and M2H2 14), showed the highest phenol biodegradation capacities (the most toxic pollutant), and were tested for the dual effect of biodegradation combined with biosurfactant production. Isolates M2H2 1 and M2H2 14 tolerated phenol concentrations up to 1500 and 1300 mgl-1, respectively, with no significant effect on biosurfactant activity. Adopting the induction regimen increased the phenol removal percentage from 2% to 66% and from 10% to 35% with isolates M2H2 1 and M2H2 14, respectively.