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임동중 한국환경농학회 2012 한국환경농학회 워크샵자료 Vol.2012 No.1
Current commercialized Bioethanol feedstocks, with the exception of woody feedstock, are biomass that have a direct effect on the world’s food supply. As such, there are moral issues at hand as well as the question of if there will be enough supply to meet the rising energy demands. In addition, mass farming of corn, the current leading feedstock in world ethanol production, uses significant amounts of pesticides and nitrogen fertilizers which in turn cause corrosion of arable land. Also, farming of any land based plants cannot avoid the use of fresh water. Stockholm Environment institute warns of serious water scarcity in the near future. Therefore nations like Korea that do not possess enough arable land and biomass need to seek out alternate sources of biomass in order to produce bioenergy in sufficient quantities. The marine environment surrounding the Korean peninsula can be effectively used for both bioenergy production and CO2 reduction. Algae, compared to other biomasses, have a very fast cultivation cycle(In case of tropical climates, it can be harvested 4~6 times annually). They are grown in the vast open sea eliminating the need for dry arable land. In addition they require very little or none of the costly resources that are required to grow other feedstock. (e.g. fresh water, fertilizer etc.) Also, the preparation and saccharification processes are much simpler than that of woody feedstock as algae do not contain lignin. As the total conversion yield is high, if it were to be mass cultivated in Southeast Asia, Bioethanol can be produced from algae at about the same level of process cost as sugar or starch based feedstock. Algae is broadly classified into two categories, macroalgae and microalgae. Macroalgae are further divided into three categories: red algae, brown algae and green algae. Bioethanol production technology with red algae feedstock will be the focus of this article. Bioethanol is gaining attention as one of the foremost bioenergies that can lower crude oil dependence. Some advantages of Bioethanol include ease of transport/ storage/use (compared with gaseous bioenergy) and ease of production (compared with butanol). The main reason why red algae is considered a suitable feedstock for ethanol production is due to its high carbohydrate content. Red algae Bioethanol production process is composed of [Saccharification] - [Fermentation] - [Separation and Refining]. The saccharification or hydrolysis process converts the polysaccharides present in red algae into monosaccharides that can in turn be used by various fermentation agents. The saccharification takes place through the use of enzymatic or acidic means. The saccharification product is then fermented into ethanol using the use of fermentation agents. The fermented ethanol is then separated and refined to yield 99.5% purity fuel grade ethanol. Compared to woody biomass that is mainly composed of lignin, C5 hemicelluose and cellulose, red algae is mainly composed of galactan and cellulose. As such, the costly and troublesome lignin removal process, essential for woody Bioethanol production, is not needed in red algae Bioethanol production. Through these Results, red algae bioethanol production will allow Korea to maintain its status as a producer nation by meeting the CO2 emission regulations set by the Kyoto protocol and further playa major role in allowing Korea to develop into a foreig nenergy independent nation.
이경미,하순득,황선희,임동중,Jae-Hyuk Jang,공재열 한국생물공학회 2004 Biotechnology and Bioprocess Engineering Vol.9 No.4
The optimization of culture conditions for the bacterium Pseudomonas aeruginosa BYK-2 KCTC 18012P, was performed to increase its rhamnolipid production. The optimum level for carbon, nitrogen sources, temperature and pH, for rhamnolipid production in a flask, were identified as 25 g/L fish oil, 0.01% (w/v) urea, 25℃ and pH 7.0, respectively. Optimum conditions for batch culture, using a 7-L jar fermentor, were 200 rpm of agitation speed and a 2.0 L/min aeration rate. Under the optimum conditions, on fish oil for 216 h, the final cell and rhamnolipid concentrations were 5.3 g/L and 17.0 g/L respectively. Fed-batch fermentation, with different feeding conditions, was carried out in order to increase, cell growth and rhamnolipid production by the Pseudomonas aeruginosa, BYK-2 KCTC 18012P. When 2.5 g of fish oil and 100 mL basal salts medium, containing 0.01% (w/v) urea, were fed intermittently during the fermentation, the final cell and rhamnolipid concentrations at 264 h, were 6.1 and 22.7 g/L respectively. The fed-batch culture resulted in a 1.2-fold increase in the dry cell mass and a 1.3-fold increase in rhamnolipid production, compared to the production of the batch culture. The rhamnolipid production-substrate conversion factor (0.75 g/g) was higher than that of the batch culture (0.68 g/g).