Biodegradation and Decolorization of Crystal Violet Dye by Cocultivation with Fungi and Bacteria

Abstract

Microbial degradation of dyes is vital to understanding the fate of dyes in the environment. In this study, a fungal strain A-3 and a bacterial strain L-6, which were identified as Aspergillus fumigatus and Pseudomonas fluorescens, respectively, had been proven to efficiently degrade crystal violet (CV) dye. The decolorization of CV dye by fungal and bacterial cocultivation was investigated. The results showed that the decolorization rate of cocultures was better than monoculture (P. fluorescens in L-6 (PF), and that of A. fumigatus A-3 (AF)). Furthermore, enzymatic analysis further revealed that Lac, MnP, Lip, and NADH–DCIP reductases were involved in the biodegradation of CV dyes. UV–visible spectroscopy, Fourier transform infrared (FT-IR) spectroscopy, and gas chromatography–mass spectrometry (GC–MS) were used to examine the degradation products. GC–MS analysis showed the presence of 4-(dimethylamino) benzophenone, 3-dimethylaminophenol, benzyl alcohol, and benzaldehyde, indicating that CV was degraded into simpler compounds. The phytotoxicity tests revealed that CV degradation products were less toxic than the parent compounds, indicating that the cocultures detoxified CV dyes. As a result, the cocultures are likely to have a wide range of applications in the bioremediation of CV dyes.

Biodegradation of crystal violet by newly isolated bacteria

“…Recently, biological approaches, particularly cocultivation techniques involving both fungal and bacterial species, have shown promise. These techniques utilize lignin-degrading enzymes such as laccase (Lac), manganese peroxidase (MnP), and lignin peroxidase (LiP), which are more effective at breaking down complex dye structures and accelerating their biodegradation ( Tian et al, 2024 ).…”