Biodegradation of crude oil by immobilized Exiguobacterium sp. AO-11 and shelf life evaluation

<jats:title>Abstract</jats:title><jats:p><jats:italic>Exiguobacterium</jats:italic> sp. AO-11 was immobilized on bio-cord at 10<jats:sup>9</jats:sup> CFU g<jats:sup>−1</jats:sup> carrier for the removal of crude oil from marine environments. To prepare a ready-to-use bioremediation product, the shelf life of the immobilized cells was calculated. Approximately 90% of 0.25% (v/v) crude oil removal was achieved within 9 days when the starved state of immobilized cells was used. The oil removal activity of the immobilized cells was maintained in the presence of oil dispersant (89%) and at pH values of 7–9. Meanwhile, pH, oil concentration and salinity affected the oil removal efficacy. The immobilized cells could be reused for at least 5 cycles. The Arrhenius equation describing the relationship between the rate of reaction and temperature was validated as a useful model of the kinetics of retention of activity by an immobilized biocatalyst. It was estimated that the immobilized cells could be stored in a non-vacuum bag containing phosphate buffer (pH 7.0) at 30 °C for 39 days to retain the cells at 10<jats:sup>7</jats:sup> CFU g<jats:sup>−1</jats:sup> carrier and more than 50% degradation activity. These results indicated the potential of using bio-cord-immobilized crude oil-degrading <jats:italic>Exiguobacterium</jats:italic> sp. AO-11 as a bioremediation product in a marine environment.</jats:p>