Biotransformation of Indole and Its Derivatives by a Newly Isolated Enterobacter sp. M9Z

Abstract

In this study, a novel bacterial strain M9Z with the ability of producing indigoids from indole and its derivatives was isolated from activated sludge and identified as Enterobacter sp. according to 16S ribosomal RNA (rRNA) sequence analysis. UV-vis spectrometry and high-performance liquid chromatography-mass spectrometry analysis indicated that the products produced from indole, 5-methylindole, 7-methylindole, and 5-methoxyindole were indigo with different substituent groups, and the possible biotransformation pathways of indole derivatives, i.e., indole(s)-cis-indole-2,3-dihydrodiol(s)-indoxyl(s)-indigoids, were proposed. The conditions of indole transformation and indigo biosynthesis by strain M9Z were optimized, and the maximal indigo yield (68.1 mg/L) was obtained when using 150 mg/L indole, 200 mg/L naphthalene, and 5 g/L yeast extract. The transformation rates of 5-methylindole, 7-methylindole, and 5-methoxyindole by strain M9Z were all close to 100 % under certain conditions, making strain M9Z an efficient indigoid producer. This is the first study of indole biotransformation and indigoid biosynthesis by genus Enterobacter.

Identification of an indole biodegradation gene cluster from Providencia rettgeri and its contribution in selectively biosynthesizing Tyrian purple

“…Comparing with those species ( Acinetobacter , A. baumannii and Cupriavidus ) have the ability of indole degradation and indigo formation ( Lin et al, 2012 ; Sadauskas et al, 2017 ; Ma et al, 2019a ; Ma et al, 2019b ), the GS -C and GS -D genes were found to be a common component among different microbials with high similarity. From previous research, GS- C homologues genes were identified as indigo-forming enzymes (monooxygenase activity was detected by oxidizing indole to indigo) in many microbials ( O'Connor et al, 1997 ; Drewlo et al, 2001 ; Doukyu et al, 2003 ; Alemayehu et al, 2004 ; Lu and Mei, 2007 ; Kwon et al, 2008 ; Ameria et al, 2015 ; Qu et al, 2015b ; Heine et al, 2019 ; Fabara and Fraaije, 2020 ). The GS -D gene encoded a flavin reductase, flavin adenine dinucleotide (FAD) cofactor, and NAD(P)H, which supposed that GS -C was possibly a cofactor-independent oxygenase that catalyzed the transformation of indole to indigo.…”