Characterization of a yellow pigmented, alkali and heavy metal tolerant Glutamicibacter sp. isolated from red mud

Abstract

Red mud ponds are waste dumping sites of bauxite mines where highly alkaline and polluted red mud or bauxite residues are deposited. They harbour many microbial strains of environmental importance. In the present study, a yellow coloured bacterial colony was isolated which showed tolerance to high pH, and metals like lead, chromium and arsenic. Genomic DNA extraction followed by partial 16S rDNA amplification and sequencing study revealed the isolate to be Glutamicibacter sp. The bacterial strain showed luxuriant growth in pH ranging from pH5 to pH 11, and salt concentration up to 8% NaCl. The pigment was isolated by methanol extraction and identified to be beta-carotene through FTIR spectroscopy. The pigment showed absorption peaks at 436 nm and 466 nm. The pigment could not show antibacterial activity significantly. The pigments showed a good free radical scavenging activity which increased significantly under stress conditions. No such studies were done from the red mud ponds of Utkal Alumina earlier. Tolerance of the bacterial strain to various heavy metals indicates presence of heavy metals in the red mud. Identification of molecular mechanisms underlying the heavy metal resistance and use of the pigments as cosmetics can be carried out in future.