Background: The native sponges of Persian Gulf are unique species facing difficult climate conditions and environmental
contamination. It is necessary to investigate these native sponges because global warming most probably destroyed many of
these creatures. Therefore, the study of the microorganisms associated with sponges will introduce new bacterial strains with
various industrial and environmental applications and, in this way, a part of the Persian Gulf biodiversity will be preserved
for posterity.
Objective: The aim of this study was the isolation and molecular identification of bacteria associated with the ability of
biodegrading crude oil from the native sponges of the Persian Gulf. Also, optimization of crude oil biodegradation was done
for one of the most efficient bacterial strains.
Materials and Methods: Isolated species were compared in terms of E24 index and growth rate in a culture medium
containing at least 2% of oil as the sole carbon source. Molecular identification was done for five bacterial strains. Using
the Taguchi experimental design, the effects of 4 factors, namely, carbon source auxiliary, organic and inorganic nitrogen
sources, salinity and pH, were evaluated at 3 levels. GC-Mass analysis was performed on the remaining oil in the culture
medium..
Results: In the initial screening of two native species of sponges, 22 bacterial strains were isolated which were capable of
decomposing oil. Five bacterial strains showed the best results and were recorded in NCBI with access numbers KY283126,
KY283128, KY285290, KY285289, and KY285288. Brevibacterium sp. (KY283128) showed the highest level of oil
degradation (about 97%) and growth rate. The results showed that the optimal oil degradation occurs in the absence of
carbon source auxiliary, at 0.5% of salinity, with NH4Cl as the nitrogen source and at a pH of 6.5.
Conclusions: This bacterial strain can be used for biodegradation in oil-contaminated areas and oil refineries. By isolating
the oil deg