Antibiofilm Activity of Biosurfactant Produced by Bacterial Strain Isolated from Petroleum-Contaminated Sites

Abstract

The escalating emergences of drug-resistant strains of Pseudomonas aeruginosa coupled with the decline in the development of new antibiotics have increased the morbidity and mortality rates during the past decades. The aim of the present work was to investigate the antibacterial and antibiofilm activity of biosurfactant produced by bacterial strain IHD19 isolated from hydrocarbon-polluted soil against biofilm forming clinical isolates of Pseudomonas aeruginosa. Isolates from petroleum-contaminated soil sample were screened and evaluated for biosurfactant production. Rapid methods such as drop collapse test, emulsification test, hemolysis test, lipase test were used for screening of biosurfactant production by bacterial strain IHD19. Bacterial strain IHD19 was selected on the basis of its efficiency to produce biosurfactant. Growth study of bacterial strain IHD19 was conducted at different physicochemical conditions aiming to find out the optimal condition for growth of bacterial strain IHD19 to obtain higher biosurfactant production. Thin-layer chromatography and FTIR analyses were done to characterize the biosurfactant produced by bacterial strain IHD19. Subsequently, the antibacterial activity of biosurfactant IHD19 on multidrug-resistant clinical isolates of Pseudomonas aeruginosa was investigated by agar well-diffusion method. Biofilm-forming clinical isolates of Pseudomonas aeruginosa were identified using crystal violet assay. Finally, the antibiofilm activity of biosurfactant IHD 19 was determined using microtiter plate assay and MBIC50 and MBIC90 were calculated. Bacterial strain IHD 19 was found positive for drop collapse test, lipase test and showed β-hemolysis on blood agar. The emulsification efficiency of biosurfactant IHD19 after 24 h (E24%) was 87.5% against engine oil. The thin-layer chromatography and FTIR analysis revealed the polymeric nature of the biosurfactant. Biosurfactant IHD19 displayed significant antibacterial and antibiofilm activity against twenty-five multidrug-resistant clinical isolates of Pseudomonas aeruginosa with more than 50% (MBIC50) in concentration range of 0.5–4 µg/ml and 90% biofilms inhibition (MBIC90) in concentration range of 16–32 µg/ml, respectively. Phylogenetic tree showed biosurfactant producing bacterial strain IHD19 to be relative to Bacillus family. With 16 s rRNA analysis the isolated bacterial strain IHD19 was identified as Bacillus pumilus. The current study proposes potential exploration of biosurfactant to subdue the issue of biofilms formation by MDR Pseudomonas aeruginosa.