• 한국미생물·생명공학회지
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• 제20권4호
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• pp.390-394
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• 1992

Aspergillus awamori var. fumeus가 균체 밖으로 생산하느 aflatoxin 분해인자의 효소적 특성을 조사 하기위하여 그 배양 여액을 aflatoxin B1과 반응시킨 결과 1시간 동안 60의 기질을 분해하였다. 반응속도는 초기에 가장 높았으며 시간이 지날 수록 낮아졌다. 반응속도와 기질농도의 관계는 이중역수 식에서 직선을 보이며 겉보기 $K_m$은 $10.2{\mu}M$로 측정되었다. 최적온도 및 최적 pH는 각각 $30^{\circ}C$ 및 5로 나타났다. 반응은 분자상 산소를 요구하며 $Co^{2+}$에 의해서 촉진되나 $Fe^{2+}$, $Ca^{2+}$, $Zn^{2+}$, $Cu^{2+}$, 및 $Ba^{2+}$ 등의 이온에 의하여 저해되었다. 또한 KCN과 metyrapone에 의하여 저해되나, $NaIO_4$, cytochrome C 및 NADPH에 의한 영향은 관찰되지 않았다.

• Journal of Microbiology and Biotechnology
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• 제34권8호
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• pp.1671-1679
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• 2024

Aspergillus flavus, the primary mold that causes food spoilage, poses significant health and economic problems worldwide. Eliminating A. flavus growth is essential to ensure the safety of agricultural products, and extracellular compounds (ECCs) produced by Bacillus spp. have been demonstrated to inhibit the growth of this pathogen. In this study, we aimed to identify microorganisms efficient at inhibiting A. flavus growth and degrading aflatoxin B₁. We isolated microorganisms from soil samples using a culture medium containing coumarin (CM medium) as the sole carbon source. Of the 498 isolates grown on CM medium, only 132 bacterial strains were capable of inhibiting A. flavus growth. Isolate 3BS12-4, identified as Bacillus siamensis, exhibited the highest antifungal activity with an inhibition ratio of 43.10%, and was therefore selected for further studies. The inhibition of A. flavus by isolate 3BS12-4 was predominantly attributed to ECCs, with a minimum inhibitory concentration and minimum fungicidal concentration of 0.512 g/ml. SEM analysis revealed that the ECCs disrupted the mycelium of A. flavus. The hydrolytic enzyme activity of the ECCs was assessed by protease, β-1,3-glucanase, and chitinase activity. Our results demonstrate a remarkable 96.11% aflatoxin B1 degradation mediated by ECCs produced by isolate 3BS12-4. Furthermore, treatment with these compounds resulted in a significant 97.93% inhibition of A. flavus growth on peanut seeds. These findings collectively present B. siamensis 3BS12-4 as a promising tool for developing environmentally friendly products to manage aflatoxin-producing fungi and contribute to the enhancement of agricultural product safety and food security.