Decolorization of Triphenylmethane Dyes by a Newly Discovered Endophytic Fungi, Colletotrichum graminicola (SWUNF9) Under Oligotrophic Conditions

Currently, bioremediation treatments are economical and eco-friendly for decolorizing toxic dyes, however, how the decolorization of triphenylmethane (TPM) dyes by endophytic fungi remains unclear. This study aimed to investigate the ability for decolorizing and detoxifying of malachite green (MG), methyl violet (MV), crystal violet (CV), and cotton blue (CB) by endophytic fungi under oligotrophic conditions. Isolate SWUNF9, was identified as Colletotrichum graminicola, which is the most promising for the four TPM dyes removal. Our findings revealed that the decolorization efficiency of isolate SWUNF9 for MG with 91% was significantly higher than other TPM dyes. The change of UV–vis peaks further suggested degradation and sorption of TPM dyes chromophores by isolating SWUNF9. Furthermore, the optimization result demonstrated the decolorization rate of four TPM dyes by isolating SWUNF9 under oligotrophic conditions could reach above 92% at 24 h. We showed that the detoxifying of TPM dyes was caused by biosorption and degradation of C. graminicola SWUNF9, respectively. Moreover, phytotoxicity tests confirmed the lower significant toxicity toward the test seeds (Vigna radiata and Zea mays) of the treatment by isolating SWUNF9 when compared to dyes before treatment. The above studies indicate that isolate SWUNF9 could be used as a potential TPM dyes adsorption and degradation agent, and enhances our understanding of endophytic C. graminicola (SWUNF9) as a promising tool for dye removal treatment of colored textile effluents.