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배승섭,나정걸,이성목,강성균,이현숙,이정현,김태완,Bae, Seung Seob,Na, Jeong Geol,Lee, Sung-Mok,Kang, Sung Gyun,Lee, Hyun Sook,Lee, Jung-Hyun,Kim, Tae Wan The Korean Society for Microbiology and Biotechnol 2015 한국미생물·생명공학회지 Vol.43 No.3
초고온성 고세균 Thermococcus onnurineus NA1은 개미산, 일산화탄소, 또는 전분 등을 이용해서 수소를 생산하는 것으로 알려져 있다. 본 연구에서는 T. onnurineus NA1의 고정화 세포를 이용한 수소생산을 고찰하였다. 고정화 실험결과, T. onnurineus NA1은 표면에 아민기가 코팅된 규조토 담체에 정전기적 인력에 의해 효과적으로 고정화되었고, 1 g의 담체에 고정화 될 수 있는 최대 세포의 양은 71.7 mg-dcw로 확인되었다. 고정화 세포를 이용한 세 번의 반복회분식 배양을 통해 개미산으로부터 수소생산 특성을 고찰하였고, 그 결과 배양이 반복됨에 따라 고정화 세포 농도의 증가에 기인하여 초기수소생산속도가 2.3 에서 4.0 mmol l<sup>−1</sup> h<sup>−1</sup>로 상당량 증가됨이 관찰되었다. 따라서, T. onnurineus NA1의 고정화세포 시스템은 수소생산을 위한 좋은 대안이 될 수 있을 것으로 사료된다. 본 연구는 초고온성 고세균의 고정화세포를 수소생산에 적용한 첫 번째 사례이다. Previously we reported that the hyperthermophilic archaeon, Thermococcus onnurineus NA1 is capable of producing hydrogen (H<sub>2</sub>) from formate, CO or starch. In this study, we describe the immobilization of T. onnurineus NA1 as an alternative means of H<sub>2</sub> production. Amine-coated silica particles were effective in immobilizing T. onnurineus NA1 by electrostatic interaction, showing a maximum cell adsorption capacity of 71.7 mg-dried cells per g of particle. In three cycles of repeated-batch cultivation using sodium formate as the sole energy source, immobilized cells showed reproducible H<sub>2</sub> production with a considerable increase in the initial production rate from 2.3 to 4.0 mmol l<sup>−1</sup> h<sup>−1</sup>, mainly due to the increase in the immobilized cell concentration as the batch culture was repeated. Thus, the immobilized-cell system of T. onnurineus NA1 was demonstrated to be feasible for H<sub>2</sub> production. This study is the first example of immobilized cells of hyperthermophilic archaea being used for the production of H<sub>2</sub>.
Kim, Min-Sik,Fitriana, Hana Nur,Kim, Tae Wan,Kang, Sung Gyun,Jeon, Sang Goo,Chung, Soo Hyun,Park, Gwon Woo,Na, Jeong-Geol Elsevier 2017 INTERNATIONAL JOURNAL OF HYDROGEN ENERGY - Vol.42 No.45
<P><B>Abstract</B></P> <P>Here, we developed a pressurized bioreactor system that increase carbon monoxide (CO) transfer efficiency in order to enhance the hydrogen productivity in the microbial water gas shift reaction by <I>Thermococcus onnurineus</I> NA1. The effects of CO pressure on the hydrogen production rate, CO consumption rate and the cell growth were investigated using small scale stainless steel bottles at various CO partial pressures. It was found that CO solubility increased by applying pressure can affect hydrogen production positively as long as the increased toxicity of CO is endurable to cells. The hydrogen productivity increased to some extent with CO pressure, but decreased drastically at the pressure higher than 4 bar. On the other hand, the effect of pressure itself on the cell's activity was not as significant as that of CO solubility increase. In the experiments at various system pressures with identical CO partial pressure of 1 bar, more than 80% of the cell activity remains even at total pressure of 10 bar. Also, it was important to determine the appropriate time to increase pressure for preventing excess CO in the reactor. Based on these results, a fermentation strategy for the pressurized system was designed and applied to a 5 L bioreactor with the continuous supply of the gas containing 60% CO. When the pressure was introduced to the bioreactor up to 4 bar at CO limitation condition, the unprecedented high productivity (360 mmol L<SUP>−1</SUP> h<SUP>−1</SUP>) could be obtained.</P> <P><B>Highlights</B></P> <P> <UL> <LI> CO gas solubility increased by pressurizing can be beneficial to H<SUB>2</SUB> production. </LI> <LI> The impact of pressure per se was marginal. </LI> <LI> CO toxicity impacts were reduced by applying pressure at mass transfer limitation condition. </LI> <LI> When the pressure was introduced to the bioreactor, the unprecedented high productivity could be obtained. </LI> </UL> </P>
Chitosan/oleamide Nanofluid for Enhancing Gas Utilization Efficiency in C1-gas Bioconversion
Eungsu KANG,Hyunsuk CHOI,Ji Yeong LEE,Min-sik KIM,Jeong Geol NA,Yoo Seong CHOI 한국생물공학회 2021 한국생물공학회 학술대회 Vol.2021 No.10
Microbial biotransformation using C1-gases (CH₄, CO) is a notable technique for sustainable, carbon-neutral chemical and fuel production. However, the low mass transfer coefficient (KLa) of C1-gases in biological processes has hampered the efficient production of value-added materials, despite efficient, nonnative strains having been recently developed. Here, we constructed a nanofluid material mainly composed of chitosan and oleamide (CS/OA), which was stably suspended with a particle size of 120.7 ± 39.0 ㎚ in aqueous culture media below pH 7.5. The kLa value was enhanced more than 1.5-fold with a reduction of surface tension even in the 0.0001 % (w/v) CS/OA nanofluid. In addition, when the nanofluid was applied into media for seed-cultivation of three C1-gas utilizing strains such as Methylomonas sp. DH-1, M. trichosporium OB3b, and Thermococcus onnurineus NA1 156T, the CS/OA nanoparticles attached to the cell surface, leading to a morphological change in the cell surface at extended lag-phase, and enhanced the specific cell growth rates (μmax), gas utilization efficiency in log-phase. Remarkably, the adapted strains from the seed culture using the CS/OA nanofluid media also had enhanced μmax in a subsequent subculture and the main culture using conventional culture media, resulting in higher C1 gas consumption, cell growth, and metabolite production such as formate and succinate. These results showed that the CS/OA nanofluid could be an effective medium component to enhance the gas utilization efficiency in C1-gas microbial bioconversion.Microbial biotransformation using C1-gases (CH₄, CO) is a notable technique for sustainable, carbon-neutral chemical and fuel production. However, the low mass transfer coefficient (KLa) of C1-gases in biological processes has hampered the efficient production of value-added materials, despite efficient, nonnative strains having been recently developed. Here, we constructed a nanofluid material mainly composed of chitosan and oleamide (CS/OA), which was stably suspended with a particle size of 120.7 ± 39.0 ㎚ in aqueous culture media below pH 7.5. The kLa value was enhanced more than 1.5-fold with a reduction of surface tension even in the 0.0001 % (w/v) CS/OA nanofluid. In addition, when the nanofluid was applied into media for seed-cultivation of three C1-gas utilizing strains such as Methylomonas sp. DH-1, M. trichosporium OB3b, and Thermococcus onnurineus NA1 156T, the CS/OA nanoparticles attached to the cell surface, leading to a morphological change in the cell surface at extended lag-phase, and enhanced the specific cell growth rates (μmax), gas utilization efficiency in log-phase. Remarkably, the adapted strains from the seed culture using the CS/OA nanofluid media also had enhanced μmax in a subsequent subculture and the main culture using conventional culture media, resulting in higher C1 gas consumption, cell growth, and metabolite production such as formate and succinate. These results showed that the CS/OA nanofluid could be an effective medium component to enhance the gas utilization efficiency in C1-gas microbial bioconversion.
Na, Jeong-Geol,Kim, Hyun-Han,Chang, Yong-Keun The Korean Society for Biotechnology and Bioengine 2005 Biotechnology and Bioprocess Engineering Vol.10 No.6
A simple, but effective on-line method for estimating the mycelial cell mass concentration from agitation speed data, a most readily-available process variable, has been developed for DO-stat cultures of Agaricus blazei. The dynamic change of dissolved oxygen concentration (DOC) in the initial transient period and the change in yield were considered in the development of the estimation algorithm or estimator. Parameters in the estimation algorithm were calculated from the agitation speed data at 20% of DOC. The proposed estimator could accurately predict the cell mass concentration regardless of DOC levels in the tested range of $10{\sim}40%$, showing a good extrapolation capability.