Screening of isolated bacteria from Persian Gulf petroleum sediments with capability of poly hydroxybutyrate production and identification of the physicochemical structure of the produced biopolymer

Polyhydroxyalkanoates (PHAs) are polymers with biodegradable and biocompatible properties that are produced by some bacteria. In the present study, petroleum sediments were applied to screen PHA-producing bacteria.

The industrial culture medium of petroleum effluent was used as a low-cost and economical medium for isolating and identifying the superior PHA-producing strain. Finally, the chemical and physical properties of the extracted biopolymer were investigated by Fourier-transform infrared spectroscopy, differential scanning calorimetry, and proton nuclear magnetic resonance.

In general, 11 out of 76 isolated bacterial strains could produce biopolymers among which, the Sb8 strain was selected as the best PHA-producing strain in the industrial medium with the cell dry weight of 44.13% and 1.2 g/l in 27 h. This strain was identified as Citreicella thiooxidans by sequencing determination. Eventually, the results of physicochemical analyses revealed that polyhydroxybutyrate (PHB) was the extracted biopolymer.

The present study is the first report on PHB production by Iranian native Citreicella thiooxidans strain by focusing on identifying and separating producing bacteria, as well as determining the type of the produced biopolymer and the production capability in a low-cost culture medium of the petroleum effluent. Considering the production of the biopolymer with a relatively high yield percentage without adding any supplement to the petroleum effluent medium, the isolated wild strain has the potential to produce PHB.