• Environmental Engineering Research
• /
• v.23 no.2
• /
• pp.216-222
• /
• 2018

The growth characteristics of Spirulina platensis were investigated using four photo-bioreactors with $CO_2$-mixed air flows. Each reactor was operated under a specific condition: 3% $CO_2$ at 50 mL/min, 3% $CO_2$ at 150 mL/min, 6% $CO_2$ at 50 mL/min, and 6% CO2 at 150 mL/min. The 3% $CO_2$ at 150 mL/min condition produced the highest algal growth rate, while the 6% $CO_2$ at 150 mL/min conditioned produced the lowest. The algal growth performance was suitably assessed by the linear growth curve rather than the exponential growth. The medium pH decreased from 9.5 to 8.7-8.8 (3% $CO_2$) and 8.4-8.5 (6% $CO_2$), of which trends were predicted only by the pH-carbonate equilibrium and the reaction kinetics between dissolved $CO_2$ and $HCO_3{^-}$. Based on the stoichiometry between the nutrient amounts and cell elements, it was predicted that depleted nitrogen (N) at the early stage of the cultivation would reduce the algal growth rates due to nutrient starvation. In this study, use of the photobioreactors capable of good light energy distribution, proper ranges of $CO_2$ in bubbles and medium pH facilitated production of high amounts of algal biomass despite N limitation.

• Korean Journal of Environmental Biology
• /
• v.31 no.2
• /
• pp.61-68
• /
• 2013

Microalgae can grow autotrophically with the supply of light, carbon dioxide and inorganic nutrients in water through photosynthesis. Generally, microalgal growth is limited by the concentrations and relative ratio of nitrogen (N) and phosphorus (P) among the nutrients in the aquatic environment. Each microalga has its specific optimum N : P ratio resulting in dominance in a particular water having similar nutrient composition. Algal bloom is an immense growth of certain microalga commonly cyanobacterium and can be sequestrated by reducing the limiting nutrient, generally P in the freshwater. Moreover, dominance of a less toxic blooming strain can be established by manipulating N : P ratio in the water. On the other hand, microalgal biomass of a certain species can be enhanced by increasing limiting nutrient and adjusting the N : P ratio to the target species. The above-mentioned eco-physiological features of microalgae can be more completely interpreted in connection with their genomic informations. Consequently, microalgal growth regulation which can be achieved on the basis of its eco-physiological and further genomic insights would be helpful not only in the control of algal bloom, but also for an increased yield of algal biomass.

• Journal of Microbiology and Biotechnology
• /
• v.23 no.10
• /
• pp.1472-1477
• /
• 2013

Microalgae have been regarded as a natural resource for sustainable materials and fuels, as well as for removal of nutrients and micropollutants from wastewater, and their interaction with bacteria in wastewater is a critical factor to consider because of the microbial diversity and complexity in a variety of wastewater conditions. Despite their importance, very little is known about the ecological interactions between algae and bacteria in a wastewater environment. In this study, we characterized the wastewater bacterial community in response to the growth of a Selenastrum gracile UTEX 325 population in a real municipal wastewater environment. The Roche 454 GS-FLX Titanium pyrosequencing technique was used for indepth analysis of amplicons of 16S rRNA genes from different conditions in each reactor, with and without the algal population. The algal growth reduced the bacterial diversity and affected the bacterial community structure in the wastewater. The following in-depth analysis of the deep-sequenced amplicons showed that the algal growth selectively stimulated Sphingobacteria class members, especially the Sediminibacterium genus population, in the municipal wastewater environment.

• Proceedings of the Korea Society of Environmental Biology Conference
• /
• 2004.05a
• /
• pp.25-25
• /
• 2004

We studied algal growth-related water quality of the Dongbok lake which is the drinking water reservoir for the Gwangju municipality. Peridinium cinctum and several diatomic algal species frequently caused water bloom throughout the lake from early spring to late autumn. With the heaviest predominance of Peridinium cintum in May 2003, COD was 13.7 mg/I in the surface layer. Highly turbid surface water with 46.8 mg/I of SS was also caused by Perdinium bloom. Peridinium bloom decisively eliminated cyanobacterial growth in the lake, otherwise cyanobacterial bloom resulted. Dense algal layer was confined in the upper several meters of the water column above the thermocline, which gives relatively algae-free water in deeper layer suitable for drinking source water supply. Upon collapse of thermocline, water quality of the surface layer was improved while deeper layer was deteriorated in terms of water quality. This paper deals with some details of water quality changes with algal growth in the Dongbok lake past two years.

• Journal of Korean Society of Environmental Engineers
• /
• v.33 no.5
• /
• pp.314-324
• /
• 2011

Algal biomass cultivated by wastewater is potentially useful resource for biodiesel production. However, little is known about algal nutrient metabolism and microbial interaction with bacteria under real municipal wastewater condition. In this work, we characterized nitrogen and phosphorus removals of municipal wastewater by a representative wastewater-growing algal population. Ankistrodesmus gracilis SAG 278-2, and analyzed its ecological interaction with wastewater bacterial communities. Compared to wastewater sludge itself, algal-bacterial co-culture improved nutrient removal. According to bacterial community analysis with 16S rRNA genes, a selective and dominant growth of a Unclassified Alcaligenaceae population resulted from algal growth in the algal-bacterial co-culture. The selectively stimulated bacterial population is phylogenetically close to Alcaligenes faecalis subsp. 5659-H, which is known to be co-present interact with algae in aquatic environment. These findings suggest that algal growth/metabolism may have effects on selection of a specific bacterial population in algal-bacterial co-cultures that can efficiently remove nutrients from municipal wastewater.

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.26 no.4
• /
• pp.217-224
• /
• 2014

Cochlodinium polykrikoides is a typical harmful algal species which generates the red-tide in the coastal zone, southern Korea. Accurate algal growth model can be established and then the prediction of the red-tide occurrence using this model is possible if the information on the optimal growth model parameters are available because it is directly related between the red-tide occurrence and the rapid algal bloom. However, the limitation factors on the algal growth, such as light intensity, water temperature, salinity, and nutrient concentrations, are so diverse and also the limitation function types are diverse. Thus, the study on the algal growth model development using the available laboratory data set on the growth rate change due to the limitation factors are relatively very poor in the perspective of the model. In this study, the growth model on the C. polykrikoides are developed and suggested as the optimal model which can be used as the element model in the red-tide or ecological models. The optimal parameter estimation and an error analysis are carried out using the available previous research results and data sets. This model can be used for the difference analysis between the lab. condition and in-situ state because it is an optimal model for the lab. condition. The parameter values and ranges also can be used for the model calibration and validation using the in-situ monitoring environmental and algal bloom data sets.

• Environmental Analysis Health and Toxicology
• /
• v.13 no.3_4
• /
• pp.133-142
• /
• 1998

Effects of phosphorous (P) and methylglyoxal (MG) on the cell number, dry weight, chlorophyll content, photosynthetic and respiratory rate, phosphate uptake and protein content of green algae (Scenedesrnus obliquus) were studied. The algal cell number from the medium treated with 0.5-1.0 mM of MG at 1/2 P or 1/4 P concentration was significantly lower than those of algae treated :with full strength of phosphrous in medium. The inhibitory effect of MG on algal cell division was enhenced at low concentration of phosphorous in medium. At the beginning of logrithmic phase of algal growth, the mean dry weight of algae from the medium without MG-treatment in 1/2 P media was significantly higher than that of algae treated with MG. After logrithmic phase of growth cycle, the mean dry weight of algae from the medium with 1.0 mM of MG-treatment in 1/4 P media was significantly lower than that of algae treated with or without MG. At logrithmic phase of algal growth, there were significant differences in the chlorophyll content among all groups of tested algae with various concentrations of P and MG. At 15 days after inoculation, the mean chlorophyll content per algal cell from the media without MG-treatment in 1/2P was significantly higher than that of other cells from MG-treated media. The adverse effect of MG at concentration of 0.5-1.0mM in 1/2 and 1/4 P media on photosynthetic rate was observed. The mean photosynthetic rate of algal cell without P and MG treatment at 15 days after inoculation was significantly higher than that of MGtreated algae. After logarithmic phase, the algal cell treated with 0.5mM of MG with full strength of phosphorous showed significantly high respiratory rate than that of other cell groups. There were significant differences in mean phosphate uptake rate among all groups of Scenedesmus obliquus at logarithmic phase. At 12 days after inoculation, phosphate uptake rate per each algal cell from the basic media without MG and P treatment was rapidly reduced which shows early introduction to stationary phase.

• Proceedings of the Korea Society of Environmental Biology Conference
• /
• 2001.12a
• /
• pp.123-123
• /
• 2001

• Ecology and Resilient Infrastructure
• /
• v.5 no.2
• /
• pp.82-87
• /
• 2018

Proliferation of algae on the surface of concrete or mortar in aquatic habitat has a negative impact on maintenance of concrete-based structures. Growth of algae may decrease stability of structure by bio-deterioration. In this study, we developed a functional mortar for restraining bio-deterioration by using $Cu^{2+}$ ion. The mortar contains soluble glass beads made of $Cu^{2+}$ ion, which can dissolve into water slowly. Mortars prepared with different ratio of glass beads (0, 2, 5, 10, and 15%) were placed in a culture medium with algae and incubated over a month period. Water chemistry, chlorophyll-a, and extracellular enzyme activities were measured. The incubation was conducted in both freshwater and seawater conditions, to assess applicability to both aquatic conditions. Overall, mortar with Cu glass exhibited lower chlorophyll-a content, suggesting that the functional mortar reduced algal growth. DOC concentration increased because debris of dead algae increased. Cu glass also decreased phosphatase activity, which is involved in the regeneration of inorganic P from organic moieties. Since, P is often a limiting nutrient for algal production, algal growth may be inhibited. Activities of ${\beta}$-glucosidase and N-acetylglucosaminidase were not significantly affected because carbon and nitrogen mineralization may not be influenced by the Cu glass beads. Our study suggests that functional mortar with Cu glass beads may reduce the growth of algae on the surface, while it has little environmental impact.

• Korean Journal of Microbiology
• /
• v.9 no.4
• /
• pp.149-154
• /
• 1971

Effect pf gibberellic acid (GA) on the growth rate, respiratory activity and solute uptake of Chlorella cells were measured and their correlation were discussed. Growth rate and respiratory activity of the algal cells are enhanced considerably by very samll amount (50 ppm) of GA treatment although they are suppressed by relatively higher concentration more than 100 ppm. Phosphate uptake of the algal cells, however, decreased even though lower concentration of GA is applied. Thereforem it is inferred that the growth enhancement of the algae by GA is not due to the increase of the permeability of the algal cells but expansion growth owing to the increase of osmotic pressure caused by the increase of hydrolase activity of the algae.