Biodegradation of indole at high concentration by persolvent fermentation with the thermophilic fungus Sporotrichum thermophile

Indole and its derivatives form a class of toxic recalcitrant environmental pollulants. Sporotrichum thermophile was grown in a persolvent fermentation system containing a large amount of indole. The medium contained up to 20% by volume soybean oil and up to 2 g L−1 indole. Most of the indole was partitioned in the organic solvent layer. When the organism was grown in the medium containing indole at 1 g L−1, indole was totally consumed after 6 days. Under a fed–batch fermentation process where daily batches of indole (1 g L−1) supplemented the microbial culture for 4 days, the biodegradation level was 3.0 g L−1. These values make this process promising and worthy of further investigation for the microbial degradation of other toxic compounds.