Escravos light crude oil degrading potentials of axenic and mixed bacterial cultures.

We assessed the relationship between growth profile and the extent of biodegradation of Escravos light crude oil by axenic and mixed bacteria cultures in a shake flask. Eleven petroleum-degrading bacteria were isolated by enrichment from oil-contaminated soils including, Pseudomonas effusa, Pseudomonas fluorescens, Pseudomonas cruciviae, Arthrobacter tumescens, Pseudomonas species, Pseudomonas tralucida, Alcaligenes metacaligenes, Micrococcus colpogenes, Bacillus badius, Nocardia paraffinae and Bacillus species. Specific growth rates of axenic cultures of the bacteria during degradation of Escravos light crude oil ranged between 0.0037 and 0.0505 h(-1), while that of the mixed cultures varied from 0.0144 to 0.1301 h(-1). The crude oil was biodegraded by between 28.71% and 99.01% for single cultures and between 12.38% and 91.58% for the mixed cultures. Although specific growth rate and biomass were important at the initial stages of biodegradation, there was no significant correlation between growth rate and biomass and the extent of biodegradation of Escravos light crude oil.