Carotenogenesis in Haloferax sp. Strain BKW301, a Halophilic Archaeon from Indian Solar Saltarns

Aims: In this study, attention has been focused on the production of carotenoid pigment by an extremely halophilic archaeon, Haloferax sp. BKW301 (NCBI Accession No. KT240044) isolated from multi-pond solar salterns of West Bengal, India.Methodology: Nutritional and environmental factors influencing the growth associated carotenogenesis by the isolate have been optimized under batch cultivation. The identity of the pigment and its antioxidant activity has been determined by spectroscopic analysis and DPPH scavenging activity respectively.Results: Growth associated production of carotenoid pigment by BKW301 has been optimized in MH medium under batch cultivation and maximum production of carotenoid pigment (1.59 mg/g) was achieved with 20% NaCl, 1% glucose, 0.5% peptone, 6% inoculum and at pH 8. Presence of light, a CVF ratio of 2.5:10, and continuous agitation at 120 rpm induced the pigment production significantly. The carotenoid pigment extracted from the cell mass showed distinct fingerprint absorption peaks at 469, 492, and 525 nm, and FTIR absorption spectra characteristic of bacterioruberin. Moreover, the purified bacterioruberin also showed high degree of DPPH scavenging activity.Conclusion: Production of significant amount of bacterioruberin under optimized cultural conditions by Haloferax sp. BKW301 and its strong DPPH scavenging activity indicated the biotechnological potential of the haloarcheaon strain for mass production of bacterioruberin and effective utilization in pharmaceutical industry.