본 실험에서는 농부산물인 밀짚을 고체배지로 사용하여 Aspergillus niger NRRL 567에서 구연산 생산 시, 발효조건과 첨가제가 구연산 생산에 미치는 영향을 단일변수(one-factor-at-a-time) 최적화를 이용하여 주요 인자의 순차적 최적화를 수행하였다. 발효 72시간에서 온도, 수분함량, 입자크기, pH와 첨가제 농도를 최적화했을 때, 각각 30 oC, 70%, 0.5~1.0 mm, pH 5.5와 4% 메탄올 첨가조건에서 최대 구연산 생산인 206.0 g/kg 건조중량 (DM)을 확인할 수 있었다. 이는 최적화 이전 구연산 최고 생산인 74.5 g/kg DM 대비 177% 증가한 결과이다. 최적화 실험에서 도출된 조건을 밀짚, 옥수수대와 피트모스(peat moss)에 적용하여 고체발효를 수행하였을 때, 발효 120시간에서 각각 231.8, 213.8, 240.2 g/kg DM 구연산 생산을 확보하였다. 본 실험 결과는 밀짚과 옥수수대 등의 목질계 농부산물을 이용한 구연산 생산 시, 고체발효법이 기존의 액체발효법의 대체가 가능함을 시사하였다.

The present study was carried out to evaluate the potential of lignocellulosic byproducts for the production of citric acid through solid-state fermentation by Aspergillus niger NRRL 567. A sequential optimization based on onefactor-at-a-time method was applied to optimize fermentation conditions and media constituents. The results obtained from the optimization indicated that 30 oC, 70% moisture content, 0.5~1.0 mm particle size, pH 5.5 and 4% methanol_x000D_ were found to be the optimum condition at 72 hr fermentation. The application the optimization resulted in an improvement of maximum citric acid production from 74.5 to 206.0 g/kg dry material (DM) from wheat straw. The optimal condition was used to produce citric acid from A. niger grown on different lignocellulosic byproducts, including wheat straw, corn stover and peat moss. A. niger produced the highest citric acid levels of 231.8, 213.8 and 240.2 g/kg DM at 120 hr fermentation, respectively.

Solid State Fermentation Citric Acid Rice Straw Optimization Agricultural by Products

Haq I, Khurshid S, Ali K, Ashraf H, Qadeer A, Rajoka I, W. J. Microbiol. Biotechnol., 17(1), 35 (2001)
Betiku E, Adesina OA, Biomass Bioenerg., 55, 350 (2013)
Vandenberghe LPS, Soccol CR, Pandey A, Lebeault JM, Bioresour. Technol., 74(2), 175 (2000)
Dhillon GS, Brar SK, Kaur S, Verma M, Ind. Crop. Prod., 41, 78 (2013)
Honda Y, Hattori T, Kirimura K, J. Biosci. Bioeng., 113(3), 338 (2012)
Kim JW, Barrington S, Sheppard J, Lee B, Process Biochem., 41(6), 1253 (2006)
Angumeenal AR, Venkappayya D, LWT-Food Sci. Technol., 50(2), 367 (2013)
Kim JW, Korean Chem. Eng. Res., 50(5), 879 (2012)
Barrington S, Kim JW, Bioresour. Technol., 99(2), 368 (2008)
Wen ZY, Chen F, Biotechnol. Bioeng., 75(2), 159 (2001)
Kim JW, Korean Chem. Eng. Res., 50(5), 874 (2012)
Ellaiah P, Srinivasulu B, Adinarayana K, Process Biochem., 39(5), 529 (2004)
Barrington S, Kim JS, Wang L, Kim JW, Korean J. Chem. Eng., 26(2), 422 (2009)
Mahadik ND, Puntambekar US, Bastawde KB, Khire JM, Gokhale DV, Process Biochem., 38(5), 715 (2002)
Kumar D, Verma R, Bhalla TC, J. Food Sci. Technol., 47(4), 458 (2010)
Rezaei PS, Darzi GN, Shafaghat H, Korean J. Chem. Eng., 27(3), 919 (2010)
Kim JW, Korean Chem. Eng. Res., 50(5), 879 (2012)
Roukas T, Enzyme Microb. Technol., 24(1-2), 54 (1999)
Nampoothiri MK, Baiju TV, Sandhya C, Sabu A, Szakacs G, Pandey A, Process Biochem., 39(11), 1583 (2004)
Betiku E, Adesina OA, Biomass Bioenerg., 55, 350 (2013)
Wang JL, Liu P, Process Biochem., 33(3), 313 (1998)
Lotfy WA, Ghanem KM, El-Helow ER, Bioresour. Technol., 98(18), 3464 (2007)
Dhillon GS, Brar SK, Verma M, Tyagi RD, Biochem. Eng. J., 54, 83 (2011)