A mixed culture of four microorganisms (B. cereus, B. thuringiensis, Geomyces pannorum, and Geomyces sp.), isolated from
crude oil-contaminated soil collected from Amazonian Ecuador
efficiently removed TPHs from crude oil in SOP and SLP. The per
cent removal of TPHs from crude oil-treated soil after 30 d in SOP
and SLP were 79.47 and 87.77, respectively. The 24 h-LD50 values for
Fig. 3. Gas chromatograms of residual PHs in soil. (a) 0-day SOP; (b) 30-d SOP; (c) 0-d SLP; and (d) 30-d SLP.
Fig. 4. Per cent survivality of A. salina after 1 h and 24 h in aqueous solutions obtained
from crude oil-treated soil. (1) 0-d; (2) 30- d SOP; and (3) 30-d SLP. Error bars
represent standard deviation (n ¼ 3). Mean values sharing the same letter are not
significantly different at p 0.05 (Tukey's test).
Fig. 5. 24 h-LD50 values for A. salina in aqueous solutions obtained from crude oiltreated soil. Error bars represent standard deviation (n ¼ 3).
N.R. Maddela et al. / International Biodeterioration & Biodegradation 108 (2016) 85e90 89
A. salina from samples collected after 30 d in SOP and SLP also
confirmed the extent of microbial removal of TPHs from crude oil.
Our results thus clearly suggest that SLP is more effective than SOP
in removing TPHs by mixed culture of soil microorganisms.
Evidently, ours is the first report on the occurrence of potential
strains of bacteria and fungi, with capabilities of degrading TPHs
under SOP or SLP, in an Ecuadorian site contaminated with crude
oil. However, field-scale studies are needed to establish the potential of this mixture of bacteria and fungi in bioremediation of
crude oil-contaminated sites