Correlation between oil substrates and biosurfactant activity using Acinetobacter junii and Pseudomonas aeruginosa

Department of Chemical Technology, University of Calcutta, 92, Acharya Prafulla Chandra Road,

Kolkata-700 009, India

E-mail : sriparna_d@yahoo.com

Manuscript received online 14 September 2012, revised 10 June 2013, accepted 14 June 2013

Two potential biosurfactant producing microorganisms – Acinetobacter junii and Pseudomonas aeruginosa were isolated from oil contaminated soils and air. The aim of this work was to evaluate the comparative potential of these two microorganisms in utilizing different vegetable and mineral oils as substrate for production of biosurfactant. The effect of pH and temperature on biosurfactant production by these two microorganisms was also evaluated. High molecular weight, high boiling mineral oils e.g. diesel resulted in better surface activity with Pseudomonas aeruginosa and produced rhamnolipid type of biosurfactant. The trend was reverse for Acinetobacter junii which produced proteoglycan type biosurfactant of comparatively less activity using petrol (low molecular weight and low boiling mineral oil fraction) as substrate. In case of vegetable oils, unsaturated C16 and C18 containing substrates were more effective for biosurfactant production especially for Pseudomonas aeruginosa. Optimum pH for Acinetobacter junii was 7.0 where as optimum growth of Pseudomonas aeruginosa was observed at pH 7.5. Optimum temperature for growth of both microorganisms was 30 ºC. This study has thus screened and identified two microorganisms viz. Pseudomonas aeruginosa and Acinetobacter junii for biosurfactant production using different vegetable and mineral oils as substrate. The biosurfactant produced by Pseudomonas aeruginosa had better surface activity considering both surface tension and emulsification index.