Optimization for the Bacterial Cellulose Production of Acetobacter xylinum KJ1 by Factorial Design

Acetobacter xylinum KJ1 efficiently producing bacterial cellulose(BC) In shaking culture was isolated from a rotten grape. The strain was used to investigate optimum operating conditions for increasing BC production and factorial design model was employed for the optimization. The results of experiments were statistically analyzed by SAS program. Reciprocal effects of each factors(carbon source concentration, shaking speeds(rpm), oxygen pressure, and CSL concentration) and culture condition of BC production were examined by getting regression equation of the dependent variable. Comparisons between experimental results and predicted results about BC concentration were done in total 24 experiments by combination of each factors using SAS program, and the correlation coefficients of BC concentration and BC yield were 0.91 and 0.81, respectively. The agitated cultures were peformed in various operation conditions of factors which affected considerably to BC production in jar fermentor. The results showed that BC concentration was 11.67 g/L in 80 hours cultivation under the condition of carbon source concentration : shaking speeds(rpm) : oxygen pressure : CSL concentration : 4% : 460 rpm : 0.28 : 6%. On the other hand BC yield was 0.42 g/g in 80 hours cultivation under the condition of carbon source concentration : shaking speeds(rpm) : oxygen pressure : CSL concentration : 4% : 564 rpm : 0.21 : 2%. The BC production could be enhanced up to more than 2.4 times by factorial design. The result of a verifying experiment under the optimal conditions determined by the factorial design to the BC production showed that the model was appropriate by obtaining BC concentration of 11.47 g/L in the optimum condition.

Factorial design에 의한 Acetobacter xylinum KJ1의 Bacterial cellulose 생산조건의 최적화

Factorial design model을 이용하여 A. xylinum KJ1의 BC생산을 위한 최적 배양조건을 결정하였다. 요인 분석을 위한 실험 계획법으로는 부분요인 분석을 통한 factorial model을 이용하였으며, 주요 실험인자인 탄소원 농도, 교반속도(rpm), 산소분압, CSL의 농도의 네 가지 factor의 영향에 의한 BC생산량의 변화를 측정하였다. SAS 프로그램을 이용하여 전체 24개의 실험계획에서 각각의 factor의 조합에 의한 BC 생산성에 관한 결과 및 예측값을 비교한 결과 BC 생산량 면에서는 상관계수($R^2$)가 0.91으로 이었고, 수율면에서는 상관계수($R^2$)는 0.81이다. 최적 BC 생산을 위한 각 factor들이 탄소원의 농도 4%, 교반속도 460 rpm, 산소분압 0.28 atm, CSL 농도 6%일 때, 이때의 BC 생산량은 11.67 g/L로 예측되었다. 그리고 BC 생산 수율면에서 최적 배양조건이 탄소원 농도 4%, 교반속도 564 rpm, 산소분압 0.21 atm, CSL 농도 2%일 때 최적의 수율 0.42 g/g를 얻을 수 있을 것으로 예측되었다. 결정된 최적 조건에서의 실증 실험 결과 11.47 g/L의 BC 생산량을 얻을 수 있었으며, 이는 fermentor상에서의 기본실험에서 얻은 4.83 g/L보다 2.4배 이상 향상된 결과이다.