Fabrication of β-glucosidase–Copper Phosphate Hybrid Nanoflowers for Bioconversion of Geniposide into Gardenia Blue

Abstract

Gardenia blue (GB) is a natural pigment widely used in textiles and food industries as an eco-friendly alternative to synthetic dyes owing to its safety, biocompatibility and chemical stability. Herein we demonstrated a recyclable, reusable and efficient catalysis system for the biosynthesis of GB from geniposide using [Formula: see text]-glucosidase embedded in copper phosphate hybrid nanoflowers. In this study, a promising [Formula: see text]-glucosidase-secreting actinomycete was isolated and identified as Streptomyces variabilis BGPA1. The secreted enzyme was successfully immobilized in nanoflowers as evidenced by scanning electron microscopy (SEM) and Fourier-transform infrared spectroscopy (FTIR) analysis. Results revealed the functionality of the prepared nanoflowers for the bioconversion of geniposide into genipin which interacts with glycine yielding the blue pigment. The optimum pH and temperature for the bioconversion were found to be 6.0 and 50∘C, respectively. Interestingly, the prepared [Formula: see text]-glucosidase–copper phosphate hybrid nanoflowers retained up to 94% of their initial activity after 15 cycles of repeated usage, indicating the remarkable recyclability and reusability of the biocatalytic system. This study suggests that [Formula: see text]-glucosidase–copper phosphate hybrid nanoflowers could be used as a potential candidate for the facile eco-friendly production of GB.