福岡県農業総合試験場研究報告

バイオリアクターによる果汁を原料にした酸性調味料の生産　
第３報　麹菌Aspergillus usamii mut.shiro-usamii IFO 6082によるクエン酸の連続生産

[摘要]麹菌Aspergillus usamii mut.shiro-usamii IFO 6082の遊離菌体を用いた通気撹絆培養により、クエン酸の連続生産を行った。単槽式連続発酵において菌体を含まない発酵ろ液だけを流出させながら胞子懸濁液を添加する操作、または菌体を含む発酵液を流出させながら菌糸培養液を添加する操作を行ったリアクターは、最高クエン酸濃度がそれぞれ42、45g/lに達したが、その後、急速にクエン酸濃度が低下した。
　単槽式を改良した2槽式連続発酵において、第１槽を1,000ml・第２槽を1,000mlとし、連続発酵開始から毎日１回、第１槽に胞子懸濁液10ml（胞子数5.7×10⁸個）を添加することにより、連続発酵開始後22日間に渡り、平均0.17g/l,hのクエン酸生成速度でクエン酸濃度30g/l以上の発酵液を長期に生産することができた。

［キーワード：麹菌、クエン酸、通気撹絆培養、連続発酵］

　Production of Sour Seasoning from Fruit Juice by Aeration-Agitation Culture. (3) Continuous Production of Citric Acid from Koji-mold Using Bioreactor. YAMASHITA Sumitaka and Hironobu MORIYAMA (Fukuoka Agric. Res. Cent., Chikushino, Fukuoka 818-0118, Japan)Bull.Fukuoka Agric.Res.Cent.18: 92 - 95(1999)

　Koji-mold of Aspergillus usamii mut. shiro-usamii IFO 6082 was used in a single or dual bioreactor to produce citric acid continuously.

Two method were applied to a single bioreactor continuous culture. One was to add spores to the reactor after draining a part of the culture medium without mycelium, and the other was to add cultured-mycelium for 48 hours after draining a part of the culture medium with mycelium. In　these method, maximum citric acid concentration of 42 and 45g/L were achieved during all of fermentation, respectively. However, in both cases, the citric acid density dropped abruptly.

　A dual bioreactor continuous culture method was improvised as an improved version of the above. The volume of the two bioreactor tanks were both 1,000ml. The procedure was to add 5.7×10^８ spores to the first tank everyday while draining a part of the culture medium with mycelium from the second. This reactor produced continuously a concentration of over 30g/L of citric acid at an average rate of 0.17g/L,h for 22 days.