New strategy to increase oil biodegradation efficiency by selecting isolates with diverse functionality and no antagonistic interactions for bacterial consortia

Abstract

The degradative ability of ten bacterial isolates individually as well as in three constructed consortia were evaluated at in-vitro and the soil environments. The bacterial consortia comprising A: five Pseudomonas, two Bacillus, one Chryseobacterium, one Ochrobactrum, and one uncultured bacterium; B: three Pseudomonas, one Bacillus, and one Chryseobacterium; C: two Pseudomonas, one Bacillus, one Ochrobactrum, and one uncultured bacterium were constructed based on degradation capacity and functional diversity. The ranking in terms of the removal effectiveness of consortia was B>A>C, in in-vitro and the soil environments. The B consortium degraded 51.6%, 61.8%, and 56.7% of the crude oil and its aliphatic and aromatic fractions, respectively. Furthermore, the B consortium represented a higher removal efficiency by 28% in the soil environment than the control. Analyses of the residual oil showed different alkane chains (≤C15 and >C25) were completely degraded (100%) in B treatment. Hence, functional diversity led to the degradation of a larger amount as well as a broader range of crude oil aliphatic and aromatic hydrocarbons. The measured interactions between isolates revealed adverse relationships between consortia components not only in in vitro but also in the soil environments. Two isolates (Ochrobactrum, and uncultured strain) had growth interference and inhibitory effects on the other components which led to a significant decline in removal efficiency in both environments. The indication was that besides the functional diversity, inter-component reactions appear to be an influential principle in the performance of microbial consortia.