• 한국수소및신에너지학회논문집
• /
• 제21권2호
• /
• pp.104-110
• /
• 2010

Photobiological hydrogen production by nitrogen-fixing unicellular cyanobacteria has long been considered to be an environmentally sound and very promising method for the future supply of renewable clean energy. We tried to find out the optimum cell concentration for $H_2$ production in each of the two new Korean nitrogen-fixing unicellular cyanobacterial strains to compare with Synechococcus sp. strain Miami BG043511. The two Korean strains, Cyanothece sp. KNU CB MAL-031 and KNU CB MAL-058, were isolated from Korean west coasts. Cell concentrations up to 17 billion cells $ml^{-1}$ were applied to the tests. High cell concentration over 15 billion cells $ml^{-1}$ resulted in drastically reduced $H_2$ production in all the three strains. The two domestic strains, however, produced 2-3 time more hydrogen than Synechococcus sp. Miami BG043511 at cell concentrations of 5-10 billion cells $ml^{-1}$. At lower cell concentrations than 2 billion cells $ml^{-1}$, MAL-031 exhibited highest $H_2$ production followed by Miami BG043511, with far less production in MAL-058. Present result suggests that Cyanothece sp. MAL-CB031 might be one of the ideal nitrogen-fixing unicellular cyanobacterial strains for the photobiological hydrogen production.

• Journal of the korean society of oceanography
• /
• 제31권1호
• /
• pp.18-22
• /
• 1996

The effect of exogenous oxygen on hydrogen photoproduction was examined in the synchronously grown cells of marine Synechococcus sp. Miami BG 043511 under conditions of high cell density (0.6-0.8 mg chl-${\alpha}$ $ml^{-1}$) and high light intensity (1000 ${\mu}$E $m^{-2}$ $s^{-1}$). Hydrogen evolution after 20-h incubation did not decline under the initial oxygen concentrations up to 20%, but declined by half under 34% oxygen. 50% and 100% oxygen gas phase did not completely inhibit the hydrogen photoproduction during 40-h incubations. After 2-day pretreatment under 100% exogenous oxygen the hydrogen photoproduction capabilities were not irreversibly inhibited, which was demonstrated in the subsequent 9-day incubation under initial 0, 50 and even under 100% oxygen gas phase. This strain could be useful for developing a hydrogen photoproduction system under atmospheric oxygen concentration.

• 한국수소및신에너지학회논문집
• /
• 제24권1호
• /
• pp.20-28
• /
• 2013

Photobiological hydrogen production by nitrogen-fixing unicellular cyanobacteria has long been considered to be an environmentally sound and very promising method for the future supply of renewable clean energy. Using six Korean nitrogen-fixing unicellular cyanobacterial strains and the Synechococcus sp. strain Miami BG043511 we performed cultivation experiments to find out the strain-specific optimal temperature for population growth and $H_2$ production. Under $20^{\circ}C$ the population growth of all the tested strains was significantly retarded in contrasts to the faster and higher growth under 25, 30 or $35^{\circ}C$. The highest growth rates in all the 7 strains were measured under $30^{\circ}C$ while the maximal biomass yields were under $30^{\circ}C$ (strains CB-MAL 026, 054, and 055) or $35^{\circ}C$ (strains 002, 031, 058, and Miami BG043511). The difference between the maximal biomass yields at $30^{\circ}C$ and $35^{\circ}C$ was not greater than 10%. The quantity of photobiologically produced $H_2$ was only slight larger under $35^{\circ}C$ than that under $20^{\circ}C$. Our result may suggest a two-step process of $H_2$ production which includes rapid and sizable production of biomass at $30^{\circ}C$ and the following high $H_2$ production at $20^{\circ}C$ by the test strains of marine nitrogen-fixing unicellular cyanobacteria.

• 한국수소및신에너지학회논문집
• /
• 제22권5호
• /
• pp.663-670
• /
• 2011

Under a daily photoperiod of 14h light and 10h dark synchronization of cell cycle in Korean Cyanothece spp. strains and $Synechococcus$ sp. strain Miami BG043511 was analyzed as to be applicable to enhanced hydrogen production. For all strains peaks of double cell were observed during the light period of a daily cycle. Peaks of maximal cell size measured by a coulter counter appeared at the peak of double cells observed under light microscope reconfirming the synchronization of daily cell cycle. The cell cycle synchronization became weakened within two days when treated with continuous illumination. Rapid detection of the peak time of double cell percentage by coulter counters may contribute to quasi-realtime feedback control for efficient production of photobiological hydrogen by unicellular cyanobacterial strains.

• 한국해양학회지:바다
• /
• 제20권3호
• /
• pp.131-140
• /
• 2015

광생물학적 수소생산 잠재력을 가진 한국산 단세포성 남세균 단종배양체를 확립하기 위하여, 2005부터 4년 동안 우리나라 연근해역의 68개 정점에서 반복적으로 시료를 채집하였다. 확보된 77개 종주의 단종배양체 가운데 6개 종주(KNU CB-MAL002, 026, 031, 054, 055, 058)는 일반적인 수소생산 조건에서 0.15 mL $H_2\;mL^{-1}$ 이상의 수소 누적량을 나타내었고, 60시간 이상의 수소 지속생산을 기록하였다. 6개 실험 종주의 수소생산을 더욱 높여주는 최적의 공정을 규명하기 위한 연구의 일환으로, 각 종주의 수온 및 염분 등급 별 성장도를 측정하여, 종주 간의 차이(interstrain difference)를 비교 하였다. 실험 종주 6개의 일일 최대 성장률은 1.78~2.08 범위로 높았고, 모든 실험 종주가 질소고정능을 나타내어, 광생물학적 수소생산 잠재력이 높은 것으로 예상되었다. 16S rRNA 분석결과, 실험 종주 들은 Cyanothece sp. ATCC51142와 높은 유사도(99%)를 보였으나, 6개의 종주 모두가 분자계통도에서는 ATCC51142와 서로 다른 clade에 별도로 나뉘어져, 본 실험 종주의 일부는 신종일 가능성이 있다. 엽록소-a는 건중량 대비 함유량이 3.4~7.8%의 범위로 나타났으며, 보조색소인 홍조소와 남조소의 함유량은 대서양산 남세균 Synechococcus sp. Miami BG03511의 절반 수준이었다. 최적 성장온도로 확인된 $30{\sim}35^{\circ}C$ 구간 밖의 온도에서는 성장이 크게 제한되었으며, $40^{\circ}C$의 고온에서는 모든 실험종주의 성장이 거의 정지됨을 확인하였다. 실험 종주들은 30 psu의 염분에서 성장이 우세하였다. 이 가운데 CB055 종주는 15 psu까지의 상대적 저염 구간에서도 높은 성장을 유지하여, 염분의 변동에 대한 내성이 높은 종주로 확인되었다. 이와 같은 광염 특성의 종주는 연안수의 계절적인 염분변화가 상대적으로 큰 온대 연안역에서 이 종주를 생물공학적으로 응용하게 될 경우, 기반해수의 계절적인 염분 변화에도 불구하고 배양 공정상의 높은 유연성을 나타내게 될 것이다. 본 연구 결과 규명된 각 종주 별 생리적 특성 자료는 향후 광생물학적 수소생산 최적공정을 확립하기 위한 모델연구에 긴요할 것이다.