International Journal of Pharma and Bio Sciences
ijpbs.net
editorijpbs@rediffmail.com (or) editorofijpbs@yahoo.com (or) prasmol@rediffmail.com
10.22376/ijpbs.2019.10.1.p1-12
Volume 10 Issue 3
2019 (July-September)
Statistical optimization of BG11 medium for enhanced zeaxanthin productivity in Synechococcus marinus (NIOT-208)
Zeaxanthin is a xanthophyll carotenoid pigment highly valued for its nutraceutical potential. It is a strong antioxidant with wide applications in food, feed, cosmetic and pharmaceutical industries. Zeaxanthin is produced by many Cyanophycean microalgae, but very few zeaxanthin accumulating strains have been reported. In this study, a two-step statistical optimization strategy involving Plackett-Burman (PB) design and response surface methodology (RSM) were successfully utilized to optimize the BG11 culture medium components for enhanced zeaxanthin production from marine Cyanophycean microalgae, lessThan i greaterThan Synechococcus marinus lessThan /i greaterThan (NIOT- 208). The media components (independent variables) of BG11 medium was screened using Plackett-Burman design to identify three crucial nutrients (Na lessThan sub greaterThan 2 lessThan /sub greaterThan EDTA, K lessThan sub greaterThan 2 lessThan /sub greaterThan HPO lessThan sub greaterThan 4 lessThan /sub greaterThan and NaNO lessThan sub greaterThan 3 lessThan /sub greaterThan ), which significantly enhanced zeaxanthin yield. Central composite design (CCD) of response surface methodology was used to optimize the concentration of significant variables. The experiments were designed using "Design Expert" software version 9.03 and the results were analyzed using two way ANOVA and a high coefficient of determination (R lessThan sup greaterThan 2 lessThan /sup greaterThan =0.984) with a low lessThan i greaterThan p lessThan /i greaterThan value (0.002) indicates that the results are reliable and significant ( lessThan i greaterThan p lessThan /i greaterThan lessThan 0.05). Validation experiments performed with optimized medium ingredients, NaNO lessThan sub greaterThan 3 lessThan /sub greaterThan (250 mg L lessThan sup greaterThan -1 lessThan /sup greaterThan ), K lessThan sub greaterThan 2 lessThan /sub greaterThan HPO lessThan sub greaterThan 4 lessThan /sub greaterThan (40 mg L lessThan sup greaterThan -1 lessThan /sup greaterThan ) and Na lessThan sub greaterThan 2 lessThan /sub greaterThan EDTA (14 mg L lessThan sup greaterThan -1 lessThan /sup greaterThan ) enhanced the zeaxanthin yield to 14.61 ± 1.29 mg L lessThan sup greaterThan -1 lessThan /sup greaterThan which is very close to the predicted value of 14.48 mg L lessThan sup greaterThan -1 lessThan /sup greaterThan . The high zeaxanthin yield accomplished by culture medium optimization resulted in 8.46 fold increase in zeaxanthin yield when compared to BG-11 medium (1.72 ± 0.22 mg L lessThan sup greaterThan -1 lessThan /sup greaterThan ). The two-step statistical optimization of culture medium thus facilitated enhanced zeaxanthin yield in lessThan i greaterThan S. marinus lessThan /i greaterThan . Further, the present study has also demonstrated purification of zeaxanthin using preparative RP-HPLC and the purified zeaxanthin was characterized using FT-Raman spectroscopic analysis and HR-MS. RP-HPLC of purified zeaxanthin indicated a high resolution molecular mass of 568.31 daltons and FT Raman spectroscopy analysis yielded three strong Raman bands corresponding to C=C stretching, C–C stretching and C–CH lessThan sub greaterThan 3 lessThan /sub greaterThan at 1537, 1173 and 1032 cm lessThan sup greaterThan −1 lessThan /sup greaterThan respectively, which are characteristic to the carotenoid zeaxanthin.
S.PRIYANKA, R. KIRUBAGARAN AND J.T. MARY LEEMA
zeaxanthin, Synechococcus marinus, Plackett-Burman, response surface methodology, Raman spectroscopy.
58-70