Use of Taguchi design for optimization of diesel-oil biodegradation using consortium of Pseudomonas stutzeri, Cellulosimicrobium cellulans, Acinetobacter baumannii and Pseudomonas balearica isolated from tarball in Terengganu Beach, Malaysia

A consortium of bacteria capable of decomposing oily hydrocarbons was isolated from tarballs on the beaches of Terengganu, Malaysia, and classified as Pseudomonas stutzeri, Cellulosimicrobium cellulans, Acinetobacter baumannii and Pseudomonas balearica. The Taguchi design was used to optimize the biodegradation of diesel using these bacteria as a consortium. The highest biodegradation of diesel-oil in the experimental tests was 93.6%, and the individual n-alkanes decomposed 87.6-97.6% over 30 days. Optimal settings were inoculum size of 2.5 mL (1.248 OD600nm); 12% (v/v) the initial diesel-oil in a minimal salt medium of pH 7.0, 30.0 gL-1 NaCl and 2.0 gL-1 NH4NO3 concentration, incubated at 42 °C temperature and 150 rpm agitation speed. Parameters significantly improved diesel-oil removal by consortium as shown by the model determination coefficient (R2 = 90.89%; P