報告書番号

U92014

タイトル（和文）

微生物によるＣＯ２固定２．高濃度ＣＯ２条件下で機能するＣｈｌｏｒｅｌｌａ属微細藻類の検索とその培養特性

タイトル（英文）

ALGAL CO2FIXATION 2.ISOLATION AND DETERMINATION OF CULTURE CHARACTERISTICS OF CHLORELLA STRAINS THAT FUNCTION IN CO2-ENRICHED ATMOSPHERES

概要 （図表や脚注は「報告書全文」に掲載しております）

火力発電所排ガス中のＣＯ２を固定して微生物タンパク質を生産するために用いることを目的として，高いＣＯ２条件下でも活発に機能する微細藻類を検索し，その培養特性について検討した。排ガスを模擬した１５％ＣＯ２濃度のガスを通気した集積培養によって，高ＣＯ２濃度条件下でも生長可能な微細藻類６株を自然界から分離した。分離株は６株ともにクロレラ属であった。６分離株のうち４株が，排ガスと同程度である１０もしくは１５％ＣＯ２でも活発に生長し，排ガスを用いた培養に適用できる可能性が示された。残りの２株は成長が若干劣った。分離株のうち最もＣＯ２固定能の高かったＨＡ－１株について，主要な培養因子に関する特性を検討した結果，好適温度や好適ｐＨの範囲が比較的広いことなどの性質を有することが分かった。以上の結果から，排ガス中のＣＯ２固定に適用するのに有望と考えられるクロレラ株を得た。

概要 （英文）

CRIEPI HAS BEEN EXAMINING CONVERSION OF CO2IN THERMAL POWER PLANT STACK GASES INTO SINGLE CELL PROTEIN (SCP) AS ONECOUNHERMEASURE TO GLOBAL WARMING. TO DEVELP EFFICIENT TECHNOLOGY TO CONVERT CO2INTO SCP,IT IS VERY IMPORTANT TO INVESTIGATE MICROALGAE THAT FUNCTION EFFECTIVELY IN CO2-ENRICHED ATMOSPHERES. THIS STUDY REPORTS THEISOLATION OF A USEFUL MICROALGAE STRAIN AND THE FEASIBILITY OF AULFIVATING CHLORELLA USING STACK GASES. MICROALGAE WERE COLLCRED FROM NATURALENVIRONMENTS SUCH AS RICE PADDY. ISOLATION WAS CARRIED OUT BY MIXED-GAS(CO2:O2:N2=15:2:83%)FLOW ENRICHMENT. SIX STRAINS OF MICROALGAE WERE ISOLATED AND ALL WERE IDENTIFIED AS CHLORELLA. THE GROWTH RATE OF ISOLATES AT HIGH-CO2CONCENTRATIONS SIMILAR TO STACK GASES WERE MEASURED TO EVALUATE THE POTENTIAL FOR CULTIVATION WITH STACK GASES. THE GROWTH RATES OF FOUR STRAINS AT HIGH-CO2CONCENTRATIONS RANGING FROM 10% TO 15% WERE MORE THAN THESE OF A REFERENCE STRAIN CHLORELLA PYRENOIDOSA NIES-226 GROWING UNDER THE OPTIMUM CO2CONCENTRATION(5%). THE GROWTH RATE OF TWO OTHER STRAINS WERE LOWER. THESE RESULTS SUGGEST THAT THESE FOUR STRAINS ARE APPLICABLE TO CULTIVATION WITH STACK GASES. THE CULTURE CHARACTERISTICS OF CHLORELLA SP.HA-1 STRAIN,WHICH SHOWED THE HIGHEST GROWTH AT 10% CO2,WERE INVESTIGATED WITH RESPECT TO MAJOR CULTURE FACTORS SUCH AS CO2-ENRICHED AIR FLOW RATE,TEMPERATURE AND CULTURE MEDIUM PH. THE BEST GROWTH WAS SHOWN AT FLOW RATES OF 0.25 AND 0.5 LITRE/MIN UTE/LITRE MEDIA,BUT THE DIFFERENCE BETWEEN 0.10 AND 1.0 LITRE MIN/UTE/LITRE MEDIA WERE SMALL. THE OPTIMUM TEMPERATURE WAS AROUND 25 TO 30 DEGREE AND THE OPTIMUM PH FOR MEDIA WAS BETWEEN 4 AND 6. THESE RESULTS INDICATE THAT THE HA-1 STRAIN CANACHIEVE GOOD GROWTH IN A COMPARATIVELY BROAD RANGE OF CULTURE CONDITIONS AND DOES NOT REQUIRE RIGIDLY CONTROLLED CONDITIONS.

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