Indigoids Biosynthesis from Indole by Two Phenol-Degrading Strains, Pseudomonas sp. PI1 and Acinetobacter sp. PI2

Abstract

In this study, two phenol-degrading bacterial strains, designated as PI1 and PI2, were isolated from activated sludge for the production of indigoids from indole. According to the 16S ribosomal RNA (rRNA) gene sequence analysis, strains PI1 and PI2 were identified as Pseudomonas sp. and Acinetobacter sp., respectively. Liquid chromatography/time-of-flight/mass spectrometry (LC/TOF/MS) was applied to analyze the metabolites during the biotransformation of indole by the phenol-degrading strains. The results indicated that both strains could catalyze the formation of four indigoids with the same prominent molecular ion (M-H)(-) peak at m/z 261.067 and molecular formula of C16H10N2O2, including indigo and a purple product, 2-(7-oxo-1H-indol-6(7H)-ylidene) indolin-3-one. Isatin and 7-hydroxyindole were detected as the intermediates. Thus, the possible pathways for the production of indigoids from indole were proposed. Subsequently, the optimal conditions for the production of indigo from indole were determined using response surface methodology, and 11.82 ± 0.30 and 17.19 ± 0.49 mg/L indigo were produced by strains PI1 and PI2, respectively. The present study should provide potential candidates for microbial production of indigoids.

Biodegradation and Biotransformation of Indole: Advances and Perspectives

“…sp. QM and PI1 could also produce indigo, and other red and purple indigoids were also generated (Ma et al, 2012 ; Wang et al, 2015 ).…”

Genome Sequence of an Indigoid-Producing Strain, Pseudomonas sp. PI1

“…Pseudomonas sp. PI1 can cometabolize indole in the presence of phenol but cannot use indole as the sole carbon source ( 9 ). Application of liquid-chromatography time-of-flight mass spectrometry revealed four products with an m/z of 262.067, all of which had the same molecular formula with indigo, i.e., C 16 H 10 N 2 O 2 .…”

Indole Degradation in a Model System and in Poultry Manure by Acinetobacter spp.

“…PI1 and Acinetobacter sp. PI2 isolated from activated sludge could biosynthesis indigo [32]. Qu et al [33] reported transformation of indole to indigo using a biphenyl dioxygenase enzyme cloned from Dyella ginsengisoli L-4 and heterologously expressed in Escherichia coli (DE3).…”