報告書番号

U93022

タイトル（和文）

高能率魚類生産のための水質浄化技術の開発８．海洋性硝化細菌の分離，培養および固定化法

タイトル（英文）

DEVELOPMENT OF WATER PURIFICATION TECHNOLOGIES FOR INTENSIVE FISH CULTURE 8.MASS CULTIVATION AND IMMOBILIZATION OF MARINE NITRIFYING BACTERIUM ISOLATED FROM CLOSED RECIRCULATING SYSTEM

概要 （図表や脚注は「報告書全文」に掲載しております）

循環濾過飼育水槽内の海洋性硝化細菌を分離し，生理学的な特性を把握するとともに大量培養と大量固定化のための条件について検討した。希釈法により得られた分離菌株は，アンモニア酸化能を持つ球菌でＮｉｔｒｏｓｏｃｏｃｃｕｓ属に分類され，３０度ｐＨ８．０～８．５，塩分２０で最も高い活性を示した。また，この条件下での培養において，培養液中の細胞濃度は４＊１０＊＊６ｃｅｌｌｓ／ｍｌであり，アンモニアの添加や亜硝酸の除去によってもその濃度は変わらなかった。大量固定化する際の最適条件としては，分離菌株を固定化した場合よりも活性汚泥を固定化した場合の方が活性が高かったことから，細胞として活性汚泥を用い，ＰＶＡ樹脂濃度は１０％（ｗ／ｖ），担体直径は約２．６～３．５ｍｍが適当であると判断された。また，この条件下で作製した固定化担体１ｌは，１日で１．１ｇ－Ｎのアンモニアを酸化する能力を有していた。

概要 （英文）

TO DEVELOP A SEAWATER TREATMENT SYSTEM FOR CLOSED RECIRCULATING FISH CULTURE,A MARINE NITRIFYING BACTERIUM WAS ISOLATED FROM THE CLOSED RECIRCULATING SYSTEM.THE EFFECTS OF ENVIRONMENTAL FACTORS ON THE AMMONIA OXIDATION RATE OF THE ISOLATED BACTERIUM WERE EXAMINED.MASS CULTIVATION AND IMMOBILIZATION OF THE ISOLATED BACTERIUM WERE ALSO CONDUCTED UNDER OPTIMUM CONDITIONS. THE RESULTS ARE AS FOLLOWS:(1)THE ISOLATED MARINE NITRIFYING BACTERIUM WAS CLASSIFIED AS A MEMBEROF THE GENUS NITROSOCOCCUS. (2)THE HIGHEST AMMONIA OXIDATION RATE OF THE ISOLATED BACTERIUM WAS OBTAINED AT 30 DEGREE C,PH 8.0-8.5 AND SALINITY 20.THE AMMONIA OXIDATION RATE WAS NOT AFFECTED BY AMMONIA CONCENTRATION. (3)IN THE MASS-CULTURE EXPERIMENTS,THE CELL DENSITY OF THE ISOLATED BACTERIUM REACHED 4X10**6 CELLS PER ML OF CULTURE MEDIUM UNDER OPTIMUM CONDITIONS.THE CELL DENSITY DID NOT INCREASE DE SPITE ADDING AMMONIA AND CHANGING THE MEDIUM. (4)THE AMMONIA OXIDATION RATE OF THE IMMOBILIZED ISOLATED BACTERIUM WAS 0.350 MG-N/DAY/1ML BEADS WHEN IMMOBILIZED AT A CELL DENSITY OF 1.3*10**8 CELLS/1ML BEADS AND PRECULTURED FOR 7 DAYS.THIS WAS MUCH LOWER THAN THAT OF BEADS INCLUDING ACTIVATED SLUDGE WITH MARINE NITRIFYING BACTERIA. (5)PEADS INCLUDING ACTIVATED SLUDGE UNDER THE FOLLOWING CONDITIONS HAVE HIGH NITRIFYING ACTIVITY AND HANDLED EASILY:10%(W/V)POLYVINYLALCHOL CONCENTRATION AND 2.6-3.5MM DIAMETER BEADS.

報告者

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