Enhancement of antibacterial and antibiofilm properties of proximadiol through microbial transformation by Rhizopus oryzae

Abstract

Staphylococcus aureus causes a spectrum of ailments, from slight skin infections to severe infections due to its virulence and antibiotic resistance. Developing new antibacterial and antibiofilm drugs is crucial for combating S. aureus infections. Increasing the bioactivity of compounds by biotransformation is a potential strategy. Rhizopus oryzae was employed to convert proximadiol (1) into pterocarptriol (2) with a satisfactory yield of 47 % (w/w). The antibacterial and antibiofilm actions of 1 and 2 were evaluated against S. aureus clinical isolates. The produced metabolite (2) showed superior antimicrobial activity with MIC values (32–128 µg/mL) compared to that of the substrate (1) (128 to 1024 µg/mL). It also demonstrated higher antibiofilm activity by the crystal violet assay than the substrate (1), as evidenced by the reduction of the percentages of strong and moderate biofilm forming strains from 88.89 % to 38.89 % and 66.67 %, respectively. Furthermore, the metabolite (2) has been shown to downregulate biofilm-related genes (icaA, fnbA, and cna) in a broad range of S. aureus clinical isolates compared to the substrate (1) using qRT-PCR. The antibacterial and antibiofilm activity was remarkably enhanced in pterocarptriol compared to proximadiol. Yet, future studies are needed to benefit from the antibacterial and antibiofilm activities of these compounds.