<i>Rhodococcus rhodochrous</i> IEGM 1360, an Efficient Biocatalyst of C3 Oxidative Transformation of Oleanane Triterpenoids

Abstract

Abstract—The optimal conditions for C3 oxidative biotransformation of 1.0 g/L pentacyclic triterpenoids oleanolic (OA) and glycyrrhetic (GA) acids were determined using the resting cells of Rhodococcus rhodochrous IEGM 1360 from the Regional Specialised Collection of Alkanotrophic Microorganisms. Suspensions of the resting cells with OD600 2.6 in pH 8.0 buffer and OD600 2.2 in pH 6.0 buffer showed the highest catalytic activity against OA and GA, which ensured the formation of 61 and 100% of their 3-oxo derivatives, respectively. Using phase contrast, atomic force, and confocal laser scanning microscopy, an adaptive response of rhodococci to the effects of OA and GA was revealed. In silico, the apoptotic and antioxidant activities of 3-oxo-OA and 3-oxo-GA, respectively, have been assumed. In vitro, a pronounced antibacterial activity of 3-oxo-OA against Micrococcus luteus, Escherichia coli, Staphylococcus aureus, and Bacillus subtilis was shown. The absence of toxic effects of the triterpenoids and their 3-oxo derivatives on aquatic and plant objects was demonstrated in silico and in vitro, respectively.