Liquid-state fermentation (LSF) and solid-state fermentation (SSF) were carried out to produce enzymes and β-glucan. The modified synthetic medium composition in liquid-state fermentation (LSF) was determined to be 5% (w/v) whole oat flour, 2% (w/v) tryptone, and 2% (w/v) rice bran. The different humidity conditions of oat by solid-state fermentation were evaluated in terms of maximum production of fungal biomass, amylase, protease, and β-glucan, which were 0.23 mg/g, 7,157.38 U/g, 413.67 U/g, and 8.26% (w/w), respectively, at 60% of humidity condition. Moreover, α-glucosidase inhibition activities of fermented oat with 60% humidity at 48 h were shown to be high 49.08% (w/w). Therefore, liquid- and solid-state fermentation processes were found to enhance the overall fermentation yields of oat to produce enzymes and β-glucan.

Oxalic acid has a nematicidal activity against the root-knot nematode Meloidogyne incognita. High producer of oxalic acid was isolated, and then named as Aspergillus niger F22. Oxalic acid production was investigated under various temperatures from 20 – 33oC and rotational speeds in 5 L jar fermenters. Yield of oxalic acid increased with decreasing temperature. The highest yield was obtained at 23oC, showing the yield of oxalic acid of 8.7 g/L, whereas oxalic acid production was least at 33oC. At 20oC, the yield was lower than that of 23oC. At a rotational speed of 300 rpm, serious oxygen depletion was present from 48 - 72 h, resulting in low productivity of 26.2 mg /L·h. When a rotational speed was set at 600 rpm, dissolved oxygen tension was over 40% and oxalic acid production increased up to approximately 55%. Viscosity during the culture differed with temperatures. Viscosity increased with the increment of temperatures. When A. niger F22 was cultured at 23oC, viscosity was 810 cP, which was favorable for oxalic acid production.

This experiment was conducted to investigate the effects of mixed culture with mycotoxigenic and non-mycotoxigenic fungi on mycotoxin production. For this work, Aspergillus flavus (aflatoxin producing strain), Aspergillus niger (non-mycotoxigenic strain) and Penicilhum griseofulvum (patulin producing strainvere cultured in 5 ml SLS medium for 15 days under single or mixed culture. Affatoxin was determined by direct competitive ELISA, whereas, patulin was measured by HPLC. The mycelial growth, pH and total acidity were also observed by general methods. The mycelial growth was slightly decreased in the mixed culture, meanwhile total acidity was increased and pH was shown lower than that in single culture. Aspergillus flavus produced 145 ㎍/ml of aflatoxin for 12 days single culture, but in mixed culture, aflatoxin was decreased to 93%, and was shown as 10.16 ㎍/ml level. Patulin production in mixed culture was also decreased to 69.3% and was shown only 23.72 ㎍/ml level as compared with in single culture.

Aspergillus niger KCTC 6144 포자를 alginate bead로 고정화하여 호박배지(포도당 9%, 호박가루 1%, pH 6)를 이용하여 구연산 발효를 수행하였다. 고정화된 A. niger 포자가 bead 내에서 발아하여 균사가 bead를 뚫고 자라났으며 30℃에서 4일간 배양 후 그 크기는 2.0∼2.5㎜에서 6∼8㎜로 커졌다. 30℃에서 5일간 진탕배양(150rpm)으로, 50ml 호박 배지가 든 250ml 삼각 flask를 사용하여. 구연산 생성의 최적 발효 조건을 검토한 결과는 다음과 같다. 탄소원으로 포도당을 12%로 올렸을 때 구연산의 생성이 최고에 달하였고, 질소 및 무기질원으로 1%의 호박가루가 구연산 생성에 가장 알맞는 농도였다. 초기 pH는 6.0, bead의 수가 100개로 하였을 때 구연산 생성이 가장 좋았으며, 포토당 12%, 호박가루 1%로 한 최적 배양 조건에서, 5일만에 구연산이 23.5g/l로 최고로 생성되었다.