• 한국미생물·생명공학회지
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• 제11권1호
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• pp.59-66
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• 1983

유포자 유산균인 Lactobacillus sporogenes 가 특이하게 균체외 $\beta$-galactosidase를 다량 생산하는 것을 발견하여 효소생산을 위한 영양요구성과 배양조건을 조사하였다. 영양요구성으로는 탄소원으로서 lactose 1%, 유기질소원으로서 peptone 1.5%, 무기질소원으로서 ammonium sulfate 0.2%, phosphorus 원으로 ammonium phosphate, dibasic을 0.8%. mineral은 potassium chloride 0.05%, ferric chloride 0.001% 첨가했을 때 최대의 효소생산을 나타내었다. 배지의 최적 initial pH는 7.0, 최적배양온도는 37$^{\circ}C$, aeration효과는 500$m\ell$용 진탕 flask에 배지량을 50~200$m\ell$ 주입, 140 strokes/min (진폭 7cm)으로 진탕 배양하였을 때 최고의 효소생산을 나타냈다. 상기의 최적조건에서 균체증식은 24시간 배양에 최고에 달하는 반면 $\beta$-galactosidase 생산은 균체내 효소생산의 경우 균체증식 속도와 비례적으로 증가하여 배양 24시간 전후에서 30U/$m\ell$로 최고치를 나타내고 균체외 효소는 배양 40시간 전후 즉, 균증식의 후기 정지기에서 38U/$m\ell$로 가장 높은 효소생산량을 보였다. 또한 fermentor 실험 역시 flask배양과 거의 비슷한 배양 양상을 보였으며 균체외 효소역가는 45U/$m\ell$로 진탕 flask 배양 결과보다 다소 양호하였다.

• Journal of Microbiology
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• 제41권3호
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• pp.224-231
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• 2003

The null pigmentation mutant (npgA1) of Aspergillus nidulans was previously characterized by its production of no pigment at any stage of its life cycle, its reduction in hyphal branching, and its delay in the asexual spore development. The chemical composition of the cell wall was also altered in npgA1 mutants that became more sensitive to Novozyme 234$\^$TM/, which is possibly due to a structural defect in the cell wall. To investigate the effects of the cell wall structure on these pleiomorphic phenomena, we examined the ultrastructure of the cell wall in the npgA1 mutant (WX17). Scanning electron micrographs (SEM) showed that after being cultured for six days, the outermost layer of the conidial wall of WX17 peeled off. Although this phenotype suggested that the cell wall structure in WX17 may be modified, examination using TEM of the fine structure of cross-sectioned hyphal wall of WX17 did not show any differences from that of FGSC4. However, staining for carbohydrates of wall layers showed that the electron-translucent layer of the cell wall was missing in WX17. In addition, the outermost layer H1 of the hyphal wall was also absent in WX17. The ultrastructural observation and cytochemical analysis of cell walls suggested that the pigmentation defect in WX17 may be attributed to the lack of a layer in the cell wall.

• Preventive Nutrition and Food Science
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• 제7권3호
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• pp.305-309
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• 2002

Raw soybean sprouts were tested for contamination with the following bacteria which have potential for pathogenesis or food spoilage : Salmonella spp., Escherichia coli O157:H7, Yersinia enterocolitica, Vibrio parahae-molyticus, Aeromonas hydrophila, Plesidomonas shigeloides, Pseudomonas aeruginosa, Staphylococcus aureus, Lis-teria monocytogenes, Bacillus cereus, Clostridium perfringens, Campylobacter jejuni, Erwinia spp., and Fusarium spp. Three of the above strains were isolated from the sprouts, and identified by morphological and biochemical methods including an API kit and ATB automated identification system. The isolate cultured in Cereus selective agar, a selective medium, was a Gram-positive, rod shaped, anaerobic spore former. The biochemical and culture tests revealed the following characteristics: catalase-positive, no growth on Simmon's citrate, NO₂ production and requirement of arginine for growth; the ATB automated identification system gave 99.8 % agreement for the identification of Bacillus cereus to the species level. The isolate cultured in Macconkey agar selective medium was Gram-negative, rod shaped and a gas former; the ATB-system gave 99.9% agreement for the identification of Aeromonas hydrophila to the species level. The isolate found in Pseudomonas isolation agar was Gram-negative, rod shaped, cytochrome oxidase-positive, a reducer of nitrates to nitrogen, and pyocyanin producer; the ATB-system gave 99.9 % agreement for the identification of Pseudomonas aeruginosa to the species level. These results indicate that the three bacteria species present in the soybean sprouts were Bacillus cereus, Aero-monas hydrophila, and Pseudomonas aeruginosa. Salmonella spp., Escherichia coli O157:H7, and Yersinia enter-ocolitica, which are associated with serious disease in humans, were not isolated from soybean sprouts examined in this study.

• 미생물학회지
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• 제50권2호
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• pp.158-163
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• 2014

된장으로부터 mannanase 생산균으로 산성 배지에서 분리된 YB-1402는 그람양성 간균으로 포자를 형성하며, 16S rDNA 염기서열과 생화학적 성질이 Bacillus amyloliquefaciens와 가장 높은 유사도를 보였다. 분리균 YB-1402는 konjac을 3% 첨가한 LB 액체배지에서 약 150 U/ml의 최대 mannanase 생산성을 보였다. 분리균의 배양상등액을 사용하여 SDS-PAGE 활성염색을 실시한 결과 분자량이 약 38 kDa로 추정되는 한 종류의 mannanase만이 관찰되었으며, $55^{\circ}C$와 pH 5.5 반응조건에서 mannanase의 최대활성을 보였다. 특히 mannanase는 pH 3.0-10의 범위에서 1시간 방치하였을 때 실활되지 않은 특성을 지니고 있었다. Locust bean gum과 mannooligosaccharides를 mannanase로 분해하였을 때 mannose, mannobiose와 mannotriose가 최종 분해산물로 관찰되었으며 mannotriose 이상의 중합도를 갖는 mannooligosaccharides를 분해하는 것으로 확인되었다.

• 한국축산식품학회지
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• 제40권4호
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• pp.578-587
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• 2020

Clostridioides (Clostridium) difficile is a Gram (+), anaerobic, spore forming, rod shaped bacterium that can produce toxin. The objective of this study is to reveal the presence of C. difficile in meat products, to analyze the ribotype diversity by PCR and to evaluate the antibiotic susceptibility of isolated strains. The organism was isolated in 22 out of 319 (6.9%) examined meat product samples and 9 out of 22 (40.9%) isolates were identified as RT027 and all isolates had the ability of toxin production. In terms of antibiotic susceptibility, all isolates were susceptive to amoxicillin-clavulanic acid, tetracycline and vancomycin and 21 (95.4%) isolates to metronidazole. On the other hand, imipenem and cefotaxim resistance was observed in all. In conclusion, the results of this comprehensive study conducted in Turkey deduced the presence of C. difficile in different meat products. Therefore, these products can be evaluated as a potential contamination source of C. difficile from animals to humans especially for elders, youngsters, long terms wide spectrum antibiotic used and immuno-suppressed individuals.

• Journal of Microbiology and Biotechnology
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• 제10권6호
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• pp.776-783
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• 2000

Various alcohol yeast strains have been isolated from main mashes of Korean traditional liquors, and their genetic diversities were previously reported [23]. In this study, the strain SHY111, showing the highest alcohol production, was tested for its fermentation and sporulation characteristics. Additionally, its haploid cells were isolated and tested for their growth and fermentation patterns. The strain was identified as Saccharomyces cerevisiae based on its morphological and physiological characteristics. The sequences of the ITS(internal transcribed spacer) and 5.8S rDNA regions of S. cerevisiae SHY111 were found to be identical to those of S. cerevisiae that was obtained from through the yeast genome project. The maximum fermentation ratio obtained by the strain SHY111 (96.7%) was almost the same as that by S. cerevisiae Balyun No. 1 (96.5%) that was a little higher than that by S. cerevisiae KCCM11215(95.8%). The strain was induced for sporulation in a sporulation liquid medium using log phase cells grown in different types of pre-sporulation media, and its haploid cells were obtained by spore dissection using a micromanipulator. The majority of the spores formed a small colony on a YPD agar plate, and the haploid yeast cells derived from the strain SHY111 showed a variety of growth and alcohol fermentation patterns. It was proposed that the fermentation patterns were related to their growth phenotypes in the most haploid strains, but possible not in some strains.

• 한국균학회지
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• 제30권1호
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• pp.1-5
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• 2002

강원대학교 EFCC에서 보관중인 번데기동충하초의 배양적 특성과 인공재배의 조건을 조사하였다. 균사생육에 적합한 배지로는 SDAY 배지와 YMA 배지, SDAY 배지, HMD 배지, PDA 배지로 조사되었으며 균사생육이 빠른 배지로는 MMM 배지로 조사되었다. 균사생장에 적합한 온도로는 $25^{\circ}C$와 pH는 $6.0{\sim}8.0$으로 조사되었다. 균사배양에 적합한 탄소원으로는 dextrose로 조사되었고 fructose와 lactose에서 균사생장이 빠른 편이였다. 균사생장이 우수한 질소원으로는 hemoglobin으로 나타났으며 tryptone에서 포자형성이 우수하였다. 무기 염류에서는 $KH_2PO_4$와 $K_2HPO_4$에서 균사생장이 우수하였으며 C/N비에서는 100 : 1의 비율에서 균사생장이 양호하였다.

• Environmental Engineering Research
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• 제10권4호
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• pp.181-190
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• 2005

Severe loss or hydrogen occurred in most anaerobic hydrogen fermentation reactors. Several selected methods were applied to suppress the consumption of hydrogen and increase the potential of production. As the first trial, pH shock was applied. The pH of reactor was dropped nearly to 3.0 by stopping alkalinity supply and on]y feeding glucose (5 g/L-d). As the pH was increase to $4.8{\pm}0.2,$ the degradation pathway was derived to solventogenesis resulting in disappearance of hydrogen in the headspace. In the aspect of bacterial community, methanogens weren't detected after 22 and 35 day, respectively. Even though, however, there was no methanogenic bacterium detected with fluorescence in-situ hybridization (FISH) method, hydrogen loss still occurred in the reactor showing a continuous increase of acetate when the pH was increased to $5.5{\pm}0.2$. This result was suggesting the possibility of the survival of spore fanning acetogenic bacteria enduring the severely acidic pH. As an alternative and additive method, nitrate was added in a batch experiment. It resulted in the increase of maximum hydrogen fraction from 29 (blank) to 61 % $(500\;mg\;NO_3/L)$. However, unfortunately, the loss of hydrogen occurred right after the depletion of nitrate by denitrification. In order to prevent the loss entangled with acetate formation, $CO_2$ scavenging in the headspace was applied to the hydrogen fermentation with heat-treated sludge since it was the primer of acetogenesis. As the $CO_2$ scavenging was applied, the maximum fraction of hydrogen was enhanced from 68 % to 87 %. And the loss of hydrogen could be protected effectively.

• Journal of Microbiology and Biotechnology
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• 제12권2호
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• pp.249-257
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• 2002

Pseudomonas fluorescens GL20 is a plant growth-promoting rhizobacterium that produces a large amount of hydroxamate siderophore under iron-limited conditions. The strain GL20 considerably inhibited the spore germination and hyphal growth of a plant pathogenic fungus, Fusarium solani, when iron was limited, significantly suppressed the root-rot disease on beans caused by F. solani, and enhanced the plant growth. The mechanism for the beneficial effect of strain GL20 on the disease suppression was due to the siderophore production, evidenced by mutant strains derived from the strain. Analysis of the outer membrane protein profile revealed that the growth of strain GL20 induced the synthesis of specific iron-regulated outer membrane proteins with molecular masses of 85- and 90 kDa as the high-affinity receptors for the ferric siderophore. In addition, a cross-feeding assay revealed the presence of multiple inducible receptors for heterologous siderophores in the strain. In order to induce increased efficacy and potential in biological control of plant disease, a siderophore-overproducing mutant, GL20-S207, was prepared by NTG mutagenesis. The mutant GL20-S207 produced nearly 2.3 times more siderophore than the parent strain. In pot trials of beans with F. solani, the mutant increased plant growth up to 1.5 times compared with that of the parent strain. These results suggest that the plant growth-promoting P. fluorescens GL20 and the genetically bred P. fluorescens GL20-S207 can play an important role in the biological control of soil-borne plant diseases in the rhizosphere.

• The Plant Pathology Journal
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• 제33권3호
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• pp.329-336
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• 2017

An experiment was conducted to evaluate the tolerance of micropropagated and mycorrhized alpinia plants to the parasite Meloidogyne arenaria. The experimental design was completely randomized with a factorial arrangement of four inoculation treatments with arbuscular mycorrhizal fungi (AMF) (Gigaspora albida, Claroideoglomus etunicatum, Acaulospora longula, and a non-inoculated control) in the presence or absence of M. arenaria with five replicates. The following characteristics were evaluated after 270 days of mycorrhization and 170 days of M. arenaria inoculation: height, number of leaves and tillers, fresh mass of aerial and subterranean parts, dry mass of aerial parts, foliar area, nutritional content, mycorrhizal colonization, AMF sporulation, and the number of galls, egg masses, and eggs. The results indicated a significant interaction between the treatments for AMF spore density, total mycorrhizal colonization, and nutrient content (Zn, Na, and N), while the remaining parameters were influenced by either AMF or nematodes. Plants inoculated with A. longula or C. etunicatum exhibited greater growth than the control. Lower N content was observed in plants inoculated with AMF, while Zn and Na were found in larger quantities in plants inoculated with C. etunicatum. Fewer galls were observed on mycorrhized plants, and egg mass production and the number of eggs were lower in plants inoculated with G. albida. Plants inoculated with A. longula showed a higher percentage of total mycorrhizal colonization in the presence of the nematode. Therefore, the association of micropropagated alpinia plants and A. longula enhanced tolerance to parasitism by M. arenaria.