Optimization of Commercial Grade NaHCO3 (Mitha Soda) Concentration for Spirulina fusiformis Cultivation

12 Samples of CFTRI (I) medium were prepared, containing 4.5 to 10g/l mitha soda with a gap of 0.5 g/l concentration. Experiment was set in beakers of 250 ml. Three days old cultures were used as the inoculums. Since the cultures of Spirulina fusiformis were homogenous, growth was followed through optical density, which was recorded initially and on every 5th day over a period of 25 days.


 * CFTRI (I) Medium
 * Mitha Soda
 * Outdoor Cultivation
 * Spirulina fusiformis

Initial density of the algal samples was adjusted to as 0.55 (Fig.1). On the 5th day, density of experimental cultures was ranging between 1.20 to 1.29 times from the initial record. Cultures having 4.5 and 5 g/l showed 1.25 times increase. The maximum growth was observed in cultures with 6g/l mitha soda. It was 1.29 times the initial density. Growth was 1.27 times in cultures with 6.5 g/l mitha soda. 1.25 times growth was observed in cultures containing 7g/l mitha soda. Cultures having 7.5, 8 and 8.5 g/l mitha soda showed 1.24 times growth. However it was 1.2 times in cultures containing 9, 9.5 and 10 g/l mitha soda (Fig.-1). All the samples showed their maximum growth on 10th day of the experiment. Thereafter, a linear reduction  was observed. Density of cultures was ranging between 1.54 to 1.69 times the initial values. Maximum growth was detected in the cultures having 6g/l mitha soda (1.69 times) and minimum was 1.54 times in cultures containing 10g/l. Cultures having 4.5 and 5g/l concentration of mitha soda showed 1.6 times growth, while with 5.5 g/l mitha soda showed 1.65 times increase. 6.5g/l concentration of mitha soda enhanced 1.67 times growth, while 7 and 7.5 g/l content showed 1.6 times increment. 1.58 times growth was reported in cultures containing 8 and 8.5 g/l mitha soda. However1.56 times growth was observed in cultures containing 9 and 9.5 g/l concentration of mith soda  (Fig.-1). On the 15th day of the experiment, a slight reduction was observed in the density of the cultures. Growth was ranging from 1.51 to 1.67 times. Cultures containing 6 and 6.5 g/l mitha soda presented maximum growth (1.67 times), while minimum growth of 1.51 times observed in cultures with 9.5 and 10 g/l mitha soda. 1.54 times growth was recorded in cultures having 4.5 and 5 g/l mitha soda, while with 5.5 g/l it was 1.64 times. The enhancement of density was 1.58 times in cultures with 7 and 7.5 g/l mitha soda. Cultures having 8 and 8.5 g/l mitha soda showed 1.56 times growth. 1.53 times increase was reported in 9g/l mitha soda containing samples (Fig.-1). On the 20th day of the experiment, density of cultures was ranging between 1.2 to 1.36 times of the initial record. It was 1.36 times in cultures containing 6 g/l mitha soda, while with 8.5 to 10 g/l concentration showed an increase of 1.2 times. Cultures having 4.5 & 5 g/l mitha soda showed 1.29 times growth while 5.5 & 6.5 g/l chemical content enhanced the density 1.33 and 1.35 times respectively. Cultures containing 7, 7.5 and 8 g/l mitha soda presented only 1.24 times enhancement (Fig.-1). 25th day’s observation revealed very much reduction in all the cultures. Density was less than the initial record. 6 and 6.5 g/l added mitha soda cultures showed 0.95 times growth. Minimum density was recorded in cultures having 10 g/l mitha soda concentration i.e. 0.82 times. Cultures containing 4.5 and 5 g/l showed 0.91 times growth. 5.5 g/l added mitha soda cultures showed 0.93 times growth. Cultures with 7 and 7.5 g/l presented 0.87 times growth. 0.85 times increase was recorded in cultures of 8 and 8.5 g/l mitha soda while 9 and 9.5 g/l cultures showed 0.84 times increase (Fig.-1).
 * Add figure no.1 here

In the present investigation highest growth of Spirulina fusiformis was recorded in 6g/l concentration of mitha soda. A remarkable correlation in algal growth and NaHCO3 concentration was reported by Huang et al. (2002). Similarly Jeeji Bai (2006) agreed that 70% of the total cost of chemicals in algal medium is due to NaHCO3, NaNO3 & K2HPO4 and modification with commercial grade NaHCO3 gives equally good results. The result of the present experiment led to the conclusion that 6 g/l content ration of mitha soda favored the growth of Spirulina fusiformis. On the 10th day of experiment all samples showed their maximum growth, however highest growth was on record in 6 g/l concentration of mitha soda. From the economy point of view, cost input for 6 g/l mitha soda was 5 times cheaper than the analytical grade NaHCO3. Similar observation was recorded by Bhatia (1996) with Spirulina labyrinthiformis, the CFTRI (I) medium with commercial grade NaHCO3 (mitha soda) at 6g/l concentration yielded as much growth as found in analytical grade 4.5 g/l NaHCO3 added medium. Gajraj (1994) reported that mitha soda at 4.5 g/l in CFTRI (I) proved to be as good as analytical grade NaHCO3 for the optimum biomass yield with Spirulina platensis. As the concluding remark 6 g/l added mitha soda in CFTRI (I) medium was better for Spirulina fusiformis cultures. Besides enhancing the growth rate, it also reduces cost input of its cultivation.