Study on the Cultural Conditions of Starch Utilizing Yeast Sporobolomyces holsaticus

전분이용성효모, Sporobolomyces holsaticus FRI Y-5의 배양조건에 관한 연구

It was investigated under several cultural conditions to produce biomass directly from starch by an strictly aerobic and amylolytic yeast, Sporobolomyces holsaticus FRI Y-5. Its optimal temperature and initial pH of medium for growth were $23^{\circ}C$ and 6.9, respectively. Activation energy, Ea, for growth was calculated to be 17.33 Kcal/mole from the Arrhenius relationship. When each of 13 nitrogen sources was added to the basal medium, $(NH_2)_2CO$ had the best effect, on which concentration of cell after 3 day incubation was 10.6 g/l and cell yield was 0.451. The yeast growth was affected by $MgSO_4,\;K_2SO_4\;and\;ZnSO_4$ as a mineral source and was best on the medium containing all of them. The addition of yeast extract (5g/l) could enhance the production of biomass and cell yield to 77% and 32%, respectively.

전분질로부터 효모균체를 직접 생산하기 위하여 분리 동정된 전분이용성 효모, Sp. holsaticus FRI Y-5의 기본적인 배양조건에 대하여 검토하였다. 이 균주는 산소를 절대적으로 요구하며, 배지의 초기 pH가 6.9일 때 최대균체량 7.2 g/l, 균체수율 0.27, 비성장속도 $0.14hr^{-1}$로 가장 좋은 생육현상을 보여 주었고 배양온도는 $23^{\circ}C$가 적온이었다. 균체생육의 활성화 에너지 Ea는 17.33 kcal/mole로 산출되었다. 검토된 13종의 질소원 가운데 $(NH_2)_2CO$가 3일 배양후 균체량이 10.69 g/l로 가장 많았으며 이때 균체수율은 0.451이었다. $SO_4\;^{-2}$염으로서 $Mg^{+2},\;K^+$ 및 $Zn^{+2}$와 유기영양원으로서 yeast extract도 균체증식에 좋은 영향을 주는 것으로 판명되었다.