| RRC ID |
55095
|
| Author |
Suzuki H, Abe T, Doi K, Ohshima T.
|
| Title |
Azoreductase from alkaliphilic Bacillus sp. AO1 catalyzes indigo reduction.
|
| Journal |
Appl Microbiol Biotechnol
|
| Abstract |
Indigo is an insoluble blue dye historically used for dyeing textiles. A traditional approach for indigo dyeing involves microbial reduction of polygonum indigo to solubilize it under alkaline conditions; however, the mechanism by which microorganisms reduce indigo remains poorly understood. Here, we aimed to identify an enzyme that catalyzes indigo reduction; for this purpose, from alkaline liquor that performed microbial reduction of polygonum indigo, we isolated indigo carmine-reducing microorganisms. All isolates were facultative anaerobic and alkali-tolerant Bacillus spp. An isolate termed AO1 was found to be an alkaliphile that preferentially grows at pH 9.0-11.0 and at 30-35 °C. We focused on flavin-dependent azoreductase as a possible enzyme for indigo carmine reduction and identified its gene (azoA) in Bacillus sp. AO1 using homology-based strategies. azoA was monocistronic but clustered with ABC transporter genes. Primary sequence identities were < 50% between the azoA product (AzoA) and previously characterized flavin-dependent azoreductases. AzoA was heterologously produced as a flavoprotein tolerant to alkaline and organic solvents. The enzyme efficiently reduced indigo carmine in an NADH-dependent manner and showed strict specificity for electron acceptors. Notably, AzoA oxidized NADH in the presence, but not the absence, of indigo. The reaction rate was enhanced by adding organic solvents to solubilize indigo. Absorption spectrum analysis showed that indigo absorption decreased during the reaction. These observations suggest that AzoA can reduce indigo in vitro and potentially in Bacillus sp. AO1. This is the first study that identified an indigo reductase, providing a new insight into a traditional approach for indigo dyeing.
|
| Volume |
102(21)
|
| Pages |
9171-9181
|
| Published |
2018-11-1
|
| DOI |
10.1007/s00253-018-9284-y
|
| PII |
10.1007/s00253-018-9284-y
|
| PMID |
30105570
|
| MeSH |
ATP-Binding Cassette Transporters / genetics
ATP-Binding Cassette Transporters / metabolism
Amino Acid Sequence
Bacillus / genetics
Bacillus / metabolism*
Bacterial Proteins / genetics
Bacterial Proteins / metabolism
Bacterial Typing Techniques / methods
Base Sequence
Catalysis
Coloring Agents / metabolism
DNA, Bacterial / genetics
Dinitrocresols / metabolism
Flavoproteins / genetics
Flavoproteins / metabolism
Indigo Carmine / metabolism*
NAD / genetics
NAD / metabolism
NADH, NADPH Oxidoreductases / genetics
NADH, NADPH Oxidoreductases / metabolism*
Nitroreductases
Phylogeny
Polygonum
Sequence Analysis, DNA
|
| IF |
3.67
|
| Resource |
| General Microbes |
JCM 32767 |
