Abstract:
Phycobiliproteins present in cyanobacteria is the major light harvesting pigments
which consists of chromophores (bilin) that are attached to cysteine residue of the
apoprotein in cyanobacteria. They elicits high active natural biochemical compound,
eligible for various application in medical as well as in aquaculture industry. Varying
physiochemical parameters especially light, affect photosynthesis and thereby the
growth of cyanobacteria as well as the phycobiliprotein content present in them.
Present study focused on optimizing light regime to produce maximum
phycobiliprotein from potential cyanobacteria. Three species of cyanobacteria,
marine Geitlerinema sp., freshwater Leptolyngbya boryana and Pseudanabaena
mucicola, were selected and cultured in four different light regime which were; (i)
24 hours artificial light (24 AL), (ii) 12 hours artificial light and 12 hours sunlight
(12 AL: 12 SL), (iii) 12 hours artificial light and 12 hours dark (12 AL: 12 D), 12
hours sunlight and 12 hours dark (12 SL: 12 D). Prior to light regime experiment, growth curve for each species in every light regime had been carried out to obtain
the stationary phase. Results showed that among the species, Pseudanabaena
mucicola cultured under 12 AL: 12 D has a significantly higher (P<0.05) total
phycobiliprotein production (149.96 ± 1.4 mg g
-1
) with a significantly high (P<0.05)
purity ratio for phycocyanin (0.92 ± 0.02), allophycocyanin (0.58 ± 0.01),
phycoerythrin (0.43 ± 0), compared to the other light regime. Leptolyngbya boryana
cultured in 12 AL: 12 D had a lower total phycobiliprotein production (15.07 ± 0.6
-1
mg g
) with a significantly low purity ratio for phycocyanin (0.08 ± 0),
allophycocyanin (0.05 ± 0.01) and phycoerythrin (0.07 ± 0). In addition, protein of
the phycobiliprotein from Pseudanabaena mucicola showed a significantly higher
concentration (P<0.05) under 12 AL: 12 SL (3.06 ± 0.2 mg mL
-1
) compared to the
other light regime.
