Novel substrate (algal protein) for cultivation of <i style="">Rhodospirillum rubrum</i>

Abstract

<i style="">Rhodospirillum rubrum</i> was grown under light anaerobic conditions with phycocyanin (C-pc) extracted from <i style="">Spirulina platensis </i>as the sole source of carbon and nitrogen<i style="">.</i> When grown under these conditions cellular components like lipids, carbohydrates, protein, carotenoids, bacteriochlorophyll were similar to the one grown with malic acid and ammonium chloride. Growth of <i style="">R. rubrum</i> increased with increase in concentration of C-pc (200 to 1000 mg/l). <i style="">R. rubrum</i> also utilized C-pc under dark anaerobic condition. With both malic acid and C-pc as carbon sources C-pc was consumed only after exhaustion of malic acid under light anaerobic condition. No aberration of cell morphology was seen under scanning electron microscope (SEM). <i style="">R. rubrum</i> utilized both phycocyanobilin and phycoprotein individually as well as in combination. When grown with 1000 mg/l of phycoprotein 450 mg/l of biomass was obtained, and with combination of phycocyanobilin (75 mg/l) and phycoprotein (925 mg/l) 610 mg/l of biomass was obtained. Phycocyanobilin alone did not inhibit the growth of <i style="">R. rubrum</i>. Utilization of C-pc with protease like activity was observed in plate assay. Protease like activity was also observed as zones around the colonies in plates containing sterilized casein, gelatin and filter sterilized bovine serum albumin. No amino acids were detected in the supernatant when analyzed with ninhydrin. Extracellular protease like activity was highest when C-pc was used as substrate (2.8 U/ml). Intracellular protease like activity was not detected in cell free extracts.