• Microbiology and Biotechnology Letters
• /
• v.10 no.4
• /
• pp.297-305
• /
• 1982

Environmental conditions of fungal growth on Korean rice grain, Milyang No.23, were studied and optimum treatment conditions of the selected fumigants for controlling fungal deterioration of rice were investigated The results are as follows. 1. Most of the fungi grew well above 80% relative humidity and 19% moisture content within 10-30 days. But at 12.5-13.0% moisture content of grains, only Aspergillus candidus, Asperillus versicolor, Penicillium chrysogenum, and Trichothecium roseum were developed within 2 months. The other fungi were only detectable for their mycelial growth under microscopic observation. 2. Among the ten fumigants tested to control the fungal growth on the rice, ethylene oxide was found to be the most effective at a leve1 of 16 mg/$\ell$ for 48 hrs treatment and the next was methyl bromide (32 mg/$\ell$), acrilonitrile and methyl iodide (64 mg/$\ell$). The other fumigants, such as ammonia, methyl formate, ethyl formate, carbon dioxide and propionic acid were found less effective under the tested conditions.

• Microbiology and Biotechnology Letters
• /
• v.10 no.3
• /
• pp.191-196
• /
• 1982

In order to prevent the losses of the rice by fungal deterioration during storage, fungal contaminants were isolated and identified from the grain samples (Milyang Nr.23) stored for seven months from December, 1978 to June, 1979 in silo, flat store and Tongari. Out of thirty cultures isolated from Korean paddy and brown rice samples, twenty seven species were identified, and there are eleven species of Aspergillus (A. caespitosus, A. condidus, A. chevalieri, A fischeri, A. fumigatus, A. flavus, A. nidulans, A. oryzae, A. ruber, A. sydowii, A. versicolor), five species of Penicillium (P. atramentosum, p. chrysogenum, P. cyaneofulvum, P. nototum, P. steckii), two species of each Alternaria (Al. faesiculata, Al. grisea) and Curvalaria (C, interseminata, C. tetromea), and one species of each Trichothecium roseum, Nigrospora sphaerica, Rhizopus nigricans, Fusarium spp., Mucor spp., Helminthosporium spp., and Gliocladiopsis spp. The major types of fungi grown on the surface of paddy during storage were A. flavus and A. candidus, while A. ruber and A. sydowii appeared in brown rice samples. And also A. candidus, A. versicolor and A. glacus groups were considered as major deteriorating microorganisms in stored brown and paddy rice in Korea.

• The Korean Journal of Mycology
• /
• v.27 no.4 s.91
• /
• pp.283-288
• /
• 1999

The effect of water activity ($a_w,\;0.9{\sim}0.995$) and temperature ($18{\sim}30^{\circ}$C) on in vitro growth and interactions between ochratoxin-producing Aspergillus ochraceus and six other fungi (Alternaria alternata, Aspergillus candidus, A. flavus, A. niger, Eurotium amstelodami, E. rubrum) isolated from maize grain were investigated. A. ochraceus and each six other species were paired and their interactions given a numerical score to obtain an index of dominance ($I_D$) for each species. Generally A. ochraceus was very competitive and dominant against other fungi. It was, however, dominanted by Alternaria alternata and A. niger at high $a_w\;(0.995\;a_w)$, and mutually antagonistic when paired with E. amstelodami and E. rubrum at low $a_w\;(0.9\;a_w)$. The growth rates of each species were also calculated under the same range of environmental conditions. They were markedly influenced by aw and temperature. At high temperature ($30^{\circ}C$), A. ochraceus grew most rapidly under slightly drier conditions ($0.95\;a_w$), while A. alternata, A. flavus and A. niger did at high water availability level ($0.995\;a_w$). At $18^{\circ}C\;and\;25^{\circ}C$, and high $a_w$ level ($0.995\;a_w$), A. alternata grew fastest, while A. candidus, E. amstelodami and E. rubrum grew very slowly. Using Biolog plates the effect of $a_w$ and temperature on utilization patterns of carbon sources in maize was evaluated. The niche overlap index (NOI) relative to A. ochraceus was determined and compared with that of each interacting species. Under high water available condition ($0.995\;a_w$). the NOI of A. ochraceus was often >0.9, indicative of the coexistence with other interacting species. However, against E. amstelodami and E. rubrum at $18^{\circ}C$, the species had NOI <0.8, indicative of occupation of different niches. At low $a_w\;(0.95\;a_w)$, NOI for A. ochraceus was <0.8 when paired with A. alternata and A. niger also suggested the occupation of different niches.

• Mycobiology
• /
• v.46 no.1
• /
• pp.52-63
• /
• 2018

In our previous studies, Bacillus megaterium KU143, Microbacterium testaceum KU313, and Pseudomonas protegens AS15 have been shown to be antagonistic to Aspergillus flavus in stored rice grains. In this study, the biocontrol activities of these strains were evaluated against Aspergillus candidus, Aspergillus fumigatus, Penicillium fellutanum, and Penicillium islandicum, which are predominant in stored rice grains. In vitro and in vivo antifungal activities of the bacterial strains were evaluated against the fungi on media and rice grains, respectively. The antifungal activities of the volatiles produced by the strains against fungal development and population were also tested using I-plates. In in vitro tests, the strains produced secondary metabolites capable of reducing conidial germination, germ-tube elongation, and mycelial growth of all the tested fungi. In in vivo tests, the strains significantly inhibited the fungal growth in rice grains. Additionally, in I-plate tests, strains KU143 and AS15 produced volatiles that significantly inhibited not only mycelial growth, sporulation, and conidial germination of the fungi on media but also fungal populations on rice grains. GC-MS analysis of the volatiles by strains KU143 and AS15 identified 12 and 17 compounds, respectively. Among these, the antifungal compound, 5-methyl-2-phenyl-1H-indole, was produced by strain KU143 and the antimicrobial compounds, 2-butyl 1-octanal, dimethyl disulfide, 2-isopropyl-5-methyl-1-heptanol, and 4-trifluoroacetoxyhexadecane, were produced by strain AS15. These results suggest that the tested strains producing extracellular metabolites and/or volatiles may have a broad spectrum of antifungal activities against the grain fungi. In particular, B. megaterium KU143 and P. protegens AS15 may be potential biocontrol agents against Aspergillus and Penicillium spp. during rice grain storage.

• Korean Journal of Food Science and Technology
• /
• v.6 no.1
• /
• pp.6-11
• /
• 1974

Four new compounds; 2,2'-methylene-bis [3, 4, 6-trichloro ${{\beta}-(o-nitroanilino)$ propionoxy} benzene]; m.p. $200{\sim}202^{\circ}C,\;C_{31}H_{22}O_8N_4Cl_6$ 2,2'-methylene-bis [3, 4, 6-trichloro ${{\beta}-(p-nitroanilino)$ propionoxy} benzene]; m.p. $168-170^{\circ}C,\;C_{31}H_{22}O_8N_4Cl_6$ : 2,2'-Methylene-bis [3, 4, 6-trichloro ${{\beta}-(o-chloro-p-nitroanilino)$ propionoxy} benzene]; m.p. $170.5-172.5^{\circ}C,\;C_{31}H_{20}O_8N_4Cl_8$ : 2,2'-Methylene-bis [3, 4, 6-trichloro ${{\beta}-(c-methyl-p-nitroanilino)$ propionoxy} benzene]; m.p. $163-164^{\circ}C,\;C_{33}H_{26}O_8N_4Cl_6$-were synthesized by Mannich reaction from 2,2'-Methylene-bis (3, 4, 6-trichloroacetoxy benzene) and their antimicrobial activities against the microorganisms Staphylococcus aureus, Escherichia coli, Bacillus subtilis Natto, Brevibacterium ammoniagenes, Candida tropicalis, Rhodotorula glutinis, Pseudomonas ovalis, Aspergillus candidus Link, Aspergillus awamori Nakazawa. Aspergillus niger var. Tieghem, Aspergillus usami Sakakuchi, Penicillium notatum-were tested. 2,2'-methylene-bis [3, 4, 6-trichloro ${{\beta}-(o-nitroanilino)$ propionoxy} benzene] showed a strong antimicrobial activity against Bacilus subtilis Natto and Brevibacterium ammoniagenes.

• Journal of Microbiology and Biotechnology
• /
• v.22 no.12
• /
• pp.1740-1748
• /
• 2012

A home-made meju sample contaminated naturally with aflatoxins was used for isolation of fungal strains. Overall, 230 fungal isolates were obtained on dichloran rosebengal chloramphenicol (DRBC) and dichloran 18% glycerol (DG18) agar plates. Morphological characteristics and molecular analysis of a partial ${\beta}$-tubulin gene and the internal transcribed spacer (ITS) of rDNA were used for the identification of the isolates. The fungal isolates were divided into 7 genera: Aspergillus, Eurotium, Penicillium, Eupenicillium, Mucor, Lichtheimia, and Curvularia. Three strains from 56 isolates of the A. oryzae/flavus group were found to be aflatoxigenic A. flavus, by the presence of the aflatoxin biosynthesis genes and confirmatory aflatoxin production by high-performance liquid chromatography (HPLC). The predominant isolate from DRBC plates was A. oryzae (42 strains, 36.2%), whereas that from DG18 was A. candidus (61 strains, 53.5%). Out of the 230 isolates, the most common species was A. candidus (34.3%) followed by A. oryzae (22.2%), Mucor circinelloides (13.0%), P. polonicum (10.0%), A. tubingensis (4.8%), and L. ramosa (3.5%). A. flavus and E. chevalieri presented occurrence levels of 2.2%, respectively. The remaining isolates of A. unguis, P. oxalicum, Eupenicillium cinnamopurpureum, A. acidus, E. rubrum, P. chrysogenum, M. racemosus, and C. inaequalis had lower occurrence levels of < 2.0%.

• Applied Biological Chemistry
• /
• v.25 no.3
• /
• pp.189-196
• /
• 1982

Seventy two samples of feedstuff were collected from commercial channels all over Korea. As a study on the moisture contents, microflora and mycotoxin production of each sample investigated. Moisture content of the samples was $11.2{\sim}15%$. Total counts of the samples were $1.8{\times}10^{2}{\sim}2.4{\times}10^{6}$ per gram. The Coli-form group were counted from 9 to $6.3{\times}10^{5}$ per gram which composed mainly of Enterobacter and Klebsiella, whereas Escherichia coli was minor ones. The contamination of many feeds was not remarkable, and only some broiler feeds was contaminated largely with Escherchia coli. Fungi were below detectable limit in 45% of the samples and the most contaminated sample had $4.5imes}10^{5}/g fungi counts.