**3. A feasibility of** *Spirulina* **annual production in the area**

Disadvantages for *Spirulina* production in this area are not only the average temperature (12.5°C), but putative aerial contamination of the medium by the dusts and microorganisms from reclaimed land in the City. The period of cultivation would be approximately <200 days for growing in open raceway ponds in this region without trials to control the disadvantages. In order to overcome the problems, the most important approach in annual cultivation in this area was to construct greenhouse over the raceway ponds. The greenhouse was made of a framework (mixture of steel and cement) and transparent glasses. The glass greenhouse enhances the culture temperature significantly (**Table 1**) and the growth period prolonged during a year. The maximum daily medium temperature of the culture was over 20°C and up to 30°C during the period from January to August. **Table 1** and **Figure 7** present year-round change data of radiation amount (μmol/m<sup>2</sup> /s), temperature of culture medium, room temperature, salinity, pH, and electricity consumption during the culture of *S. maxima* from April 2011 to March 2012. As for illumination intensity during the study period, the maximum value was 1590 μmol/m<sup>2</sup> /s, and the minimum value was 7 μmol/m<sup>2</sup> /s. Year-round water temperature of culture raceway for *S. maxima* was between 16.0 and 33.0°C, and mean water temperature was 23.6 ± 3.2°C.

for 20 minutes at 10°C at 3000 RPM. The supernatants were repeatedly collected until the color came off. After collecting all the chlorophyll, the supernatant was filtered using a 0.2 μm syringe filter, and the absorbency of each replicate was at 625, 647, and 664 nm using phosphate blank buffer with spectrophotometer (Optizen POP bio). Concentration of chlorophyll

Ca(mg/L) = (12.62 × A664) − (2.99 × A647) − (0.04 × A625) (4)

mg \_\_\_

Various parameters of the system were measured on a daily basis including room temperature (TENMARS) and light intensity (Lux Meter TM-205), water temperature (UNIS thermometer), pH (pH METER D-51, HORIBA), and salinity (SALT MATER YK-31SA). Although humidity was not a variable of interest, it seems the humidity was dropping in the plant as the level of medium kept in the plant was consistently lowering by evaporation. Evaporation amount was measured during August when culture medium was highly evaporated. To specify the

0.02 mg/L, Co, Mo, and B 0 mg/L while Fe, Zn, Cu and Mn were not detected, and pH was 7.3). A statistical program (IBM SPSS, NY, USA) was used for statistical analysis in order to test significance of environmental factors and pigments and biomass of *S. maxima* (one way ANOVA, Tukey test, *P* values <0.05). Monthly variations among climatic and culture conditions, biomass, biochemical components, and pigment concentrations were statistically analyzed by one way ANOVA with Pearson's multiple range tests at p < 0.05 (SPSS version 12.0, NY, USA) for the identification of significant seasonal differences during the study period. All analyses

Disadvantages for *Spirulina* production in this area are not only the average temperature (12.5°C), but putative aerial contamination of the medium by the dusts and microorganisms from reclaimed land in the City. The period of cultivation would be approximately <200 days for growing in open raceway ponds in this region without trials to control the disadvantages. In order to overcome the problems, the most important approach in annual cultivation in this area was to construct greenhouse over the raceway ponds. The greenhouse was made of a framework (mixture of steel and cement) and transparent glasses. The glass greenhouse enhances the culture temperature significantly (**Table 1**) and the growth period prolonged during a year.

<sup>L</sup> ) <sup>×</sup> acetone volume (mL) \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ sample weight (g) <sup>×</sup> \_\_\_\_\_\_\_\_\_\_\_\_ <sup>1</sup> <sup>L</sup>

<sup>1000</sup> mL (5)

), daily evaporation rate was


2−

/h. The amount of evaporation was then supplemented

4 6.4 mg/L, Ca 20 mg/L, Cl 13.6 mg/L, SO4

was then calculated using below formula [45].

70 Cyanobacteria

Chlorophyll <sup>−</sup> *<sup>a</sup>* (mg/g) <sup>=</sup> Ca(

measured and then averaged as ml/m2

were performed on triplicate samples.

daily with underground tap water in KIOST (HCO3

**2.7. Measurement of climatic and culture conditions**

amount of water being evaporated each day per unit area (m2

11.4 mg/L, Na 8.64 mg/L, Mg 3.99 mg/L, K 1.97 mg/L, T-N 1.66 mg/L, NO3

**3. A feasibility of** *Spirulina* **annual production in the area**

Temperature of culture medium showed a change in a range of 20.2–26.8°C from April 4, 2011 to May 31. The highest water temperature of the year was 33.0°C on July 26 as an effect of increase in outer temperature. In addition, the average evaporation rate in August 2011 was 701 ± 136.4 ml/m2 /h. Water temperature gradually decreased from October, went below 20°C during the second week of December and recorded the lowest water temperature of the year at 16.0°C on February 23, 2012. Culture medium temperature for optimal growth of *Spirulina* was between 35 and 37°C, and should be kept at least at 15–20°C [2]. Since severe air temperature in this area was recorded from −18 to 36°C, and it was below 10°C on average in the winter, the ORS with glass greenhouse was electrically heated by the boiler during the period from late October to early April to maintain at least 15°C, the lowest temperature for *Spirulina* culture. These results should serve as fundamental data for setting temperature and running a boiler in order to maintain optimal medium temperature in the winter.

The mean initial salinity of May and June was 16.6 ± 0.9 psu due to the effect of added tap water. As culture days increase, salinity concentration showed a range of change between 13.1 and 18.4 psu during the year due to effects of evaporation of culture medium and supplementation of freshwater. In addition, the mean salinity concentration during the entire culture period was 16.5 ± 1.3 psu. The pH change during the culture period showed a relatively small variation between 9.9 and 11.9. Variation of pH from May 4, 2011 to September 9 was between 9.9 and 10.97, pH change between September 14 and September 30 was ranging between 11.15 and 11.90, and then it went down to below 11.0 from October 4. The ending pH on March 16 was 9.97. Internal room temperature of the plant during the culture period was in the range of 3.2–55.0°C, and the mean room temperature was 24.3 ± 10.5°C. The mean total electricity consumption (kWh) of the microalgae pilot plant was 10.3 ± 1.1 kWh per day during the initial culture between April 4, 2011 and May 4, during which the boiler was operated for maintenance of optimal medium temperature (20.2–26.1°C). Boiler operation was stopped between May 6, 2011 and October 16, 2011 for optimal temperature, during which 1.3 ± 0.6 kWh of electricity was used on average per day.

The range of biomass of *S. maxima* that was produced year-round using batch culture method in the raceway system with glass greenhouse structure in the present study was 5.68–37.67 g/m2 /d, in which the highest productivity of the year was recorded as 37.67 g/m2 /d in the summer when temperature increased. According to a study on *S. platensis* culture in a raceway system (750 L) by Richmond et al. [46], productivity was 15–27 g/m2 /d, whereas a study on culture of *S. platensis* in a raceway system (135,000 L) conducted in Spain showed 2–17 g/m2 /d [47]. Considering that limiting factors important for growth and productivity of microalgae are solar radiation, carbon supply, water temperature, and dissolved oxygen [5, 46, 48], a control system on these factors are also critical. BIM designing technology that was introduced in the present study to predict these effects had advantages including investigation of spatiotemporal


**Table 1.** Monthly average data of water temperature (WT), room temperature (RT), solar radiation (SR), salinity, pH, and total energy consumption in the microalgae pilot plant.

relevance of construction using 3D modeling, and prediction of problematic factors in advance

**Figure 7.** Annual variations of daily data on medium water temperature (A), room temperature (B), solar radiation (C), salinity (D), pH (E) and use of total electric power (F) in the *S. maxima* culture pond during the period from April 4, 2011

in desirable *Spiruina* biomass produced from the facility that designed based on an environ

to harvest of *S. maxima* for component analysis and supplementation of freshwater for evapora

in August when temperature of culture water was high, which was statistically significant

When comparing the results of this study with most preceeding studies, the raceway system with a glass greenhouse structure in the present chapter achieved the maximum aerial pro

ductivity (**Table 3**). In addition, despite the continuous study in batch culture method without

mental analysis (atmospheric temperature and radiation amount) known as major factors of *S. maxima* growth, and predictions of environmental interference (e.g., shadow effect in **Figure 3**). **Table 2** and **Figure 8** show year-round biomass of *S. maxima* during the culture between April 8, 2011 and March 15, 2012.Variations of biomass and daily productivity were 0.227–1.507 g/L

/d, respectively, during the culture period, and mean values were

± 4.3 g/m

2

/d, respectively. The mean daily productivity of April when

/d. The mean daily productivity gradually increased

/d. Thereafter, there were changes in productivity due

2

± 4.8 g/m

Cultivating *Spirulina maxima*: Innovative Approaches http://dx.doi.org/10.5772/intechopen.74265

2

/d) in annual average was obtained.

/d) was recorded in October.

–38], which resulted


73



/d) was achieved

including an analysis of environmental interference as known already [36

and 14.2

to March 16, 2012.

0.96

(p

± 9.6–31.42

± 0.24 g/L and 24.2

culture was started was 14.2

from May reaching to 23.92

± 4.8 g/m 2

± 5.90 g/m

< 0.05), and the lowest productivity of the year (18.81

resupply of nutrients, a high aerial productivity (24.2 g/m

2

± 8.1 g/m

± 2.98 g/m

tion of culture medium. The highest productivity of the year (31.42

2

2

**Figure 7.** Annual variations of daily data on medium water temperature (A), room temperature (B), solar radiation (C), salinity (D), pH (E) and use of total electric power (F) in the *S. maxima* culture pond during the period from April 4, 2011 to March 16, 2012.

relevance of construction using 3D modeling, and prediction of problematic factors in advance including an analysis of environmental interference as known already [36–38], which resulted in desirable *Spiruina* biomass produced from the facility that designed based on an environmental analysis (atmospheric temperature and radiation amount) known as major factors of *S. maxima* growth, and predictions of environmental interference (e.g., shadow effect in **Figure 3**). **Table 2** and **Figure 8** show year-round biomass of *S. maxima* during the culture between April 8, 2011 and March 15, 2012.Variations of biomass and daily productivity were 0.227–1.507 g/L and 14.2 ± 9.6–31.42 ± 4.8 g/m2 /d, respectively, during the culture period, and mean values were 0.96 ± 0.24 g/L and 24.2 ± 5.90 g/m2 /d, respectively. The mean daily productivity of April when culture was started was 14.2 ± 8.1 g/m2 /d. The mean daily productivity gradually increased from May reaching to 23.92 ± 2.98 g/m2 /d. Thereafter, there were changes in productivity due to harvest of *S. maxima* for component analysis and supplementation of freshwater for evaporation of culture medium. The highest productivity of the year (31.42 ± 4.8 g/m2 /d) was achieved in August when temperature of culture water was high, which was statistically significant (p < 0.05), and the lowest productivity of the year (18.81 ± 4.3 g/m2 /d) was recorded in October. When comparing the results of this study with most preceeding studies, the raceway system with a glass greenhouse structure in the present chapter achieved the maximum aerial productivity (**Table 3**). In addition, despite the continuous study in batch culture method without resupply of nutrients, a high aerial productivity (24.2 g/m2 /d) in annual average was obtained.

**2011** **Apr**

> WT

RT SR

822.2 ±

480.4 ±

519.4 ±

219.4 ±

351.0 ±

604.4 ±

382.2 ±

354.2 ±

328.0 ±

336.4 ±

371.8 ±

317.4 ±

404.6

460.2

Salinity

pH TEC **Table 1.**

plant.

290.6

72.5

42.0

38.9

39.1 WT: water temperature (°C); RT: room temperature (°C); SR: solar radiation (μmol/m2/s); TEC: total energy consumption (kWh).

Monthly average data of water temperature (WT), room temperature (RT), solar radiation (SR), salinity, pH, and total energy consumption in the microalgae pilot

38.5

144.4

331.6

475.3

453.2

440.6

389.9

9.69 ± 0.2

10.4 ± 0.1

10.3 ± 0.2

10.4 ± 0.3

10.4 ± 0.3

11.1 ± 0.4

10.5 ± 0.1

10.5 ± 0.1

10.6 ± 0.3

10.3 ± 0.3

10.2 ± 0.2

10.0 ± 0.1

16.2 ± 0.1

15.6 ± 1.3

16.5 ± 0.8

18.1 ± 0.7

16.5 ± 1.6

16.3 ± 0.8

17.0 ± 0.4

16.2 ± 0.9

17.5 ± 1.3

16.4 ± 1.4

15.3 ± 1.9

13.5 ± 0.9

397.6

391.4

179.4

318.6

377.1

330.2

351.8

214.7

310.8

344.7

29.3 ± 4.1

26.4 ± 4.1

28.1 ± 3.8

34.8 ± 8.0

37.0 ± 4.6

35.9 ± 6.2

28.2 ± 3.5

22.9 ± 4.8

14.0 ± 3.6

10.8 ± 4.5

10.8 ± 4.8

15.7 ± 3.9

22.4 ± 1.3

23.3 ± 1.7

25.2 ± 1.9

27.7 ± 2.4

29.0 ± 1.8

25.6 ± 1.9

21.2 ± 1.8

23.9 ± 2.4

21.3 ± 1.8

19.5 ± 1.4

20.4 ± 2.2

22.6 ± 1.6

**May**

**Jun**

**Jul**

**Aug**

**Sep**

**Oct**

**Nov**

**Dec**

**Jan**

**Feb**

**Mar**

72 Cyanobacteria

**2012**


n.d.: not determined.

**Table 2.** Monthly average data of biomass and productivity of *S. maxima* in the microalgae pilot plant.

**Figure 8.** Annual variation on the biomass concentration of two times weekly-harvested *S. maxima* during a culture period.

pigment contents were also identified [49–53]. Markou et al. [54] reported that although CHO content of *S. platensis* was between 10 and 20% in general, the limitation of phosphorus components in nutrition source resulted in an increase to 60–65%. In addition, Markou et al. [55] reported that a control of medium components for *S. platensis* caused elevation of CHO content among general components in a study on conversion of microalgae components to bioethanol. CHO content in the present study on culture of *S. maxima* showed a year-round change between 20.06–51.37%, and significantly increased at the later stage of culture. Since the present study performed a year-round experiment in batch–culture method, it seems that nutrition sources including phosphorus component was limited at the later stage, which might have caused elevation of CHO content and reduction of protein content. Batista et al. [56] reported protein content of *S. maxima* as 44.9 ± 1.8%, and Usharani et al. [57] reported protein content of *Spirulina* as 55–70%. Protein content in the present study was 40.08% in the beginning of culture and 23.71–47.64% in year-round content. Protein contents of *S. maxima* in year-round culture were the highest in July 2011 and the lowest in January 2012. In addition, protein content was significantly correlated with medium temperature and solar radiation. Jacob-Lopes et al. [58] reported that the change of light cycles (day/night) was closely related with microalgae production, and production decreased as the condition of darkness continued. Protein

**Table 3.** Comparison of biomass productivities of various microalgal species in outdoor open pond culture (modified

5.68–37.67 *Spirulina maxima* Ansan, South

**Cultivation system Culture** 

Inclined thin layer

Inclined thin layer

Circular central pivot pond

Semi-open raceway 10,000–

from Borowitzka et al. [61]).

15,000

pond

pond

**volume (L)**

**Productivity (g/m2 /d)**

Raceway 110 20–37 *Dunaliella salina* Perth,

Raceway 600 5–40 *Tetraselmis* sp. Japan Matsumoto et al. [63] Raceway — 1.6–3.5 *Dunaliella salina* Spain Garcia et al. [64]

Raceway 750 15–27 *Spirulina platensis* Israel Richmond et al. [46]

Raceway 282 14.47 ± 0.16 *Spirulina platensis* Italy Pushparaj et al. [25] Raceway 135,000 2–17 *Spirulina* sp. Spain Jimenez et al. [15, 37] Raceway — 9–13 *Spirulina* sp. Mexico Olguin et al. [66] Raceway 500 11.2 *Tetraselmis* sp. Japan Matsumoto et al. [67] Raceway 300–600 5–26 *Tetraselmis suecica* Italy Pedroni et al. [68]

1000 10–30 *Chlorella* sp. Czech Republic

*obliquus*

Open culture system 2400–16,200 19–22 *Chlorella* sp. China Tsukuda et al. [72]

~2500 19 *Scenedesmus* 

Raceway — 8.2 *Spirulina platensis* USA (California) Belay [65]

**Species Location References**

Australia

and Spain

Korea

1960 1.61–16.47 *Chlorella* sp. Japan Kanazaqa et al. [71]

Moheimani and Borowitzka [29]

75

Cultivating *Spirulina maxima*: Innovative Approaches http://dx.doi.org/10.5772/intechopen.74265

Doucha and Livansky

[69]

In this study

Rupite, Bulgaria Dilov et al. [70]

Thus, it has confirmed a foundation to use a raceway system with a glass greenhouse structure or photobioreactor for countries with four distinct seasons.

**Table 4** presents year-round ratios of protein, carbohydrate (CHO), and lipid contents in *S. maxima*. Protein content of *S. maxima* in April 2011 when culture was started was 40.08%, which gradually increased to 47.64% in July, the highest. As culture period became longer, ratio of protein gradually decreased and recorded 23.71% in February 2012, the lowest of the year. Protein content was higher from the spring to the early fall compared to other components, which had significant correlations with temperature of culture medium and solar radiation (p < 0.05). Ratio of CHO was 36.81% in April 2011 when culture was started, which decreased to 20.06% in June. Ratio of CHO highly increased from September 2011, and reached a peak of 42.19% in January in 2012, which was contrasted to the content of protein. Thus, protein and CHO contents exhibited a significant inverse correlation depending on season (p < 0.05, r2 = 0.8542). Similar to the results of preceding studies, high protein contents were found in *S. maxima*, and changes in protein and CHO depending on season, and changes in


**Table 3.** Comparison of biomass productivities of various microalgal species in outdoor open pond culture (modified from Borowitzka et al. [61]).

Thus, it has confirmed a foundation to use a raceway system with a glass greenhouse structure

**Figure 8.** Annual variation on the biomass concentration of two times weekly-harvested *S. maxima* during a culture

**2011 2012**

1.26 ± 0.2

31.42 ± 4.8

**Table 2.** Monthly average data of biomass and productivity of *S. maxima* in the microalgae pilot plant.

Biomass (g/L)

74 Cyanobacteria

Productivity (g/ m2 /d)

period.

0.57 ± 0.4

14.2 ± 9.6

n.d.: not determined.

0.96 ± 0.2

23.92 ± 5.5

1.02 ± 0.1

25.38 ± 3.5

1.19 ± 0.2

29.65 ± 3.8

**Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar**

0.75 ± 0.2

18.81 ± 4.3

0.88 ± 0.2

21.95 ± 3.9

1.01 ± 0.1

25.20 ± 3.3

0.96 ± 0.1

24.09 ± 3.0

0.96 ± 0.1

23.97 ± 3.3

0.95 ± 0.2

23.65 ± 5.2

0.97 ± 0.1

24.26 ± 3.1

**Table 4** presents year-round ratios of protein, carbohydrate (CHO), and lipid contents in *S. maxima*. Protein content of *S. maxima* in April 2011 when culture was started was 40.08%, which gradually increased to 47.64% in July, the highest. As culture period became longer, ratio of protein gradually decreased and recorded 23.71% in February 2012, the lowest of the year. Protein content was higher from the spring to the early fall compared to other components, which had significant correlations with temperature of culture medium and solar radiation (p < 0.05). Ratio of CHO was 36.81% in April 2011 when culture was started, which decreased to 20.06% in June. Ratio of CHO highly increased from September 2011, and reached a peak of 42.19% in January in 2012, which was contrasted to the content of protein. Thus, protein and CHO contents exhibited a significant inverse correlation depending on season (p < 0.05, r2 = 0.8542). Similar to the results of preceding studies, high protein contents were found in *S. maxima*, and changes in protein and CHO depending on season, and changes in

or photobioreactor for countries with four distinct seasons.

pigment contents were also identified [49–53]. Markou et al. [54] reported that although CHO content of *S. platensis* was between 10 and 20% in general, the limitation of phosphorus components in nutrition source resulted in an increase to 60–65%. In addition, Markou et al. [55] reported that a control of medium components for *S. platensis* caused elevation of CHO content among general components in a study on conversion of microalgae components to bioethanol. CHO content in the present study on culture of *S. maxima* showed a year-round change between 20.06–51.37%, and significantly increased at the later stage of culture. Since the present study performed a year-round experiment in batch–culture method, it seems that nutrition sources including phosphorus component was limited at the later stage, which might have caused elevation of CHO content and reduction of protein content. Batista et al. [56] reported protein content of *S. maxima* as 44.9 ± 1.8%, and Usharani et al. [57] reported protein content of *Spirulina* as 55–70%. Protein content in the present study was 40.08% in the beginning of culture and 23.71–47.64% in year-round content. Protein contents of *S. maxima* in year-round culture were the highest in July 2011 and the lowest in January 2012. In addition, protein content was significantly correlated with medium temperature and solar radiation. Jacob-Lopes et al. [58] reported that the change of light cycles (day/night) was closely related with microalgae production, and production decreased as the condition of darkness continued. Protein


**4. Conclusion**

ous studies.

**Acknowledgements**

**Conflict of interest**

**Thanks**

**Nomenclature**

The authors declare no conflicts of interest.

supported by the KIOST and Ministry of Ocean and Fisheries.

AOAC the association of official analytical chemists

BIM building information modeling CFD computational fluid dynamics

CHO carbohydrate GF/C glass microfiber

A glass greenhouse pilot plant for microalgal culture fitting to temperate climate was designed based on 3D modeling designing BIM technology in KIOST. The bottom of the raceway system was placed 600 mm deep into the ground, and culture depth was kept at 400 mm, so that heat energy was efficiently stored in order to maintain thermal effects for a long time, and its structure was helpful in maintaining optimal temperature even in the winter. *S. maxima* was continuously cultured for a year in batch culture without further supply of nutrients, and the raceway system with a glass greenhouse structure in the present chapter achieved the maximum aerial productivity compared with most previ-

Cultivating *Spirulina maxima*: Innovative Approaches http://dx.doi.org/10.5772/intechopen.74265 77

This research was supported by collective research grants from the Korea Institute of Ocean Science & Technology (PE99511). Also, this paper was studied with the support of 'Development of integrated technologies for developing biomaterials using by magma seawater' (PM60110) and the 'Marine Biotechnology Program' funded by Ministry of Ocean and Fisheries, Korea.

We would like to thank the staffs of the Research Group of Integrated Use of Marine Biomass of Jeju International Marine Science Center in Korea Institute of Ocean Science and Technology (KIOST), who supported and collected the annual data. Our research activities were strongly

**Table 4.** Results of biochemical analysis of dry powder of *S. maxima*.

contents of *S. platensis* increased to 70.90 ± 2.37% at sunrise, and became 57 ± 0.69% at sunset, indicating that it tends to remarkably decrease compared to the daytime [59]. On the contrary, it was reported that CHO content was higher at the sunset time (33.81 ± 0.66%) than the sunrise time (19.48 ± 1.48%). Thus, it would be necessary to study the maintenance of protein content by application of phosphate-feed condition and LED illumination environment after the early fall when temperature of culture medium and amount of sunlight decline.

Year-round contents of phycocyanin *S. maxima* produced in the present study were 12–93 mg/g. Phycocyanin content (mg/g) of *S. maxima* was 28.5 ± 0.9 mg/g in April 2011 when culture was started. Then, it gradually decreased and the mean content became 14.8 ± 3.1 mg/g in June, which was the lowest. It showed a trend of increase from July, and the mean phycocyanin concentration of September 2012 was 91.1 ± 4.6 mg/g, which was the maximum of the year. Thereafter, phycocyanin contents again decreased and recorded 24.5 ± 9.5 mg/g in its mean value in February 2012. Chlorophyll-*a* content of *S. maxima* was 6.1 ± 0.1 mg/g in April 2011 when culture was started, and then the mean content was 6.3 ± 2.0 mg/g in August when radiation amount was relatively high, which was the highest of the year. Afterwards, chlorophyll-*a* concentration decreased to 1.8 ± 0.6 mg/g in February 2012, which was the lowest of the year. However, although content of chlorophyll-*a* was at the highest in the summer similar to the correlation between year-round contents of phycocyanin and amount of sunlight, there was no consistent year-round significance. In general, cell growth and phycocyanin production are closely related with light conditions [60, 61]. However, phycocyanin content was the highest in September 2011 when light conditions were the best in the present study, though there was no consistent significance throughout the year. Chlorophyll-*a* contents showed 6.3 ± 2.0 mg/g in August 2011, the maximum value, and 1.7 ± 0.1 mg/g in January 2012, the minimum value. It has been reported that as the light energy that microalgae received increased, chlorophyll contents also significantly increased [62], and the present study also showed the highest chlorophyll-*a* content in August when radiation amount was relatively high. Despite the significance of monthly pigment contents, however, there was no constant year-round significance between pigments and amount of sunlight.
