Eco-friendly degradative decolourisation and detoxification of azo dye Amido Black 10B by Bacillus sp. strain AK1

ABSTRACT

In this study, an azo dye Amido Black 10B was decolourised and degraded by using bacterium Bacillus sp. strain AK1. The strain decolourised 96% of the dye in 30 h at 100 mg L⁻¹ dye concentration. Decolourisation under different sets of conditions, such as increasing dye concentration (100–600 mg L⁻¹), pH (5–11), temperature (25–55°C) and salt levels (10–40 g L⁻¹), was studied and found that the strain could decolourise up to 600 mg L⁻¹ of the dye by about 54% in 72 h at pH 7 and 35°C. The bacterium also exhibited the ability to act under varied pH from 5 to 11, temperature from 25°C to 55°C and salt levels of up to 30 g L⁻¹. The azoreductase enzyme responsible for the breaking of azo bond exhibited the activity of 1.5371 µM min⁻¹ mg⁻¹ protein. The products of dye degradation were identified by using UV–Visible spectroscopy and HPLC. The decolourisation also resulted in a decline in toxicity, as indicated by phytotoxicity assessment. There was also a corresponding decrease in the BOD and COD of the decolourised sample by more than 85%, which indicates the reduction in the pollution loads after decolourisation.

KEYWORDS:

• Amido Black 10B
• toxicity
• Bacillus sp
• decolourisation
• azoreductase
• BOD/COD

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

One of the authors Dr T. B. Karegoudar received the financial support from University Grants Commission (UGC), New Delhi, India [F.4-27/2015/DRS-II (SAP-II)] in the form of Special Assistance Programme (SAP) sanctioned to the Department of Biochemistry, Gulbarga University, Kalaburagi.

Notes on contributors

Ramesh S. Masarbo

Ramesh Masarbo is Assistant Professor in the Department of Chemistry, A. V. Patil Degree College, Aland, Karnataka, India. He obtained his PhD from Gulbarga University, Kalaburagi, India. His main research fields include bioremediation of toxic chemicals including synthetic dyes. He has published seven research papers in reputed international journals from Taylor & Francis, Springer, etc.

Joan Chebet

Joan Chebet is a research student pursuing her PhD degree from the Department of Biochemistry, Kuvempu University, Shivamogga, India. She is studying dye degradation using bacteria.

H. C. Shrishail

H. C. Shrishail is Assistant Professor in the Department of Applied Botany, Kuvempu University, Shivamogga, India. He obtained his PhD from Gulbarga University, Kalaburagi. His main research area is plant taxonomy and biodiversity. He has published many books and research papers.

T. B. Karegoudar

T. B. Karegoudar is a retired professor in the Department of Biochemistry at Gulbarga University, Kalaburagi, India. His main research fields include microbial degradation of harmful chemicals and biotransformation. He has published more than 80 research papers in leading journals of Elsevier, Springer, Taylor & Francis, Wiley, etc. He has been awarded with UGC-BSR Faculty fellow.