• 한국식품위생안전성학회지
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• 제28권2호
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• pp.174-180
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• 2013

본 연구에서는 토마토의 생산 및 유통단계에서의 위해 미생물 오염도 정도를 파악하고 유통과정 중 외부 손상으로 인해 과즙 유출시 미생물의 증식능력을 측정하기 위해 E. coli O157:H7와 L. monocytogenes의 성장을 토마토 추출물 함량(0.1, 1.0, 10%) 및 다양한 배양온도(5, 15, 25, $35^{\circ}C$)에서 측정하였다. 수확단계에서는 APC 작업 종사자의 장갑에서 총 호기성 세균이 7.77 log로 가장 높게 나타났고, 배양 양액에서 대장균군과 B. cereus가 각각 0.33 log 검출되었다. 수확 후 처리과정으로 APC 과정을 거친 토마토에서 총 호기성 세균이 유의적으로 높게 나타났다. 그 외에 S. aureus, Salmonella spp. 는 검출되지 않았다. 재배방법에 따른 일반, 유기농, 무기농 토마토에서의 미생물 분포도의 유의적인 차이는 나타나지 않았다. 포장 방법 중 봉지 포장제품이 박스 포장제품에 비해 대장균군이 유의적으로 높게 나타났으며 세척에 의한 미생물 저감화 효과는 나타나지 않았다. 토마토 추출물 함량이 높을수록 E. coli O157:H7와 L. monocytogenes의 성장이 높게 나타났으며, 토마토 추출물 10%인 경우 $5^{\circ}C$ 조건에서 가장 낮았고, 15, 25, $35^{\circ}C$에서 72시간 배양시 각각 7.33~8.51, 7.73~8.60 log CFU/g으로 증식하였다.

• 한국유기농업학회지
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• 제23권3호
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• pp.523-534
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• 2015

본 연구는 미생물제제의 일종인 yeast culture 및 코팅 처리된 vitamin-C의 첨가 급여를 통해 비육 말기 Holstein 거세우의 증체 및 도체형질에 미치는 영향을 조사하기 위한 목적으로 실시하였다. 평균체중이 $714{\pm}13.60kg$인 18개월령 Holstein 거세우 24두를 공시동물로 이용하였으며 각각 8두씩 3개 시험구로(대조구, MC급여구, CVC급여구) 완전임의 배치하여 출하 전 3개월간 사양시험을 실시하였다. MC급여구는 yeast culture를 일일 30 g, 코팅 처리된 vitamin-C는 일일 10 g씩 매일 아침 사료급여 시 top dressing형태로 급여하였다. 일당증체량은 MC급여구가 가장 높았으며 사료요구율은 MC급여구와 CVC급여구에서 가장 낮았다. 등지방두께, 배체장근 및 육량은 시험구간 유의차가 없었다. 지육중량과 성숙도는 MC급여구에서 가장 높았으며, 지방색은 CVC급여구에서 가장 높게 나타났다. 이상의 결과를 종합해 보면 출하 3개월 전 Holstein 거세우에게 항생제 대체제로 미생물제제인 yeast culture 또는 코팅 처리된 vitamin-C의 급여는 육질에는 큰 효과가 없으나 육량, 지육중량, 사료요구율 등에 긍정적인 영향을 줄 수 있을 것으로 판단된다. 아울러 미생물제제와 vitamin-C를 함께 급여하면 더욱 좋은 효과가 있을 것으로 예상된다.

• Mycobiology
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• 제33권1호
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• pp.41-50
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• 2005

Results from an innovative approach to improve remediation in the rhizosphere by encouraging healthy plant growth and thus enhancing microbial activity are reported. The effect of arbuscular mycorrhizal fungi (Am) on remediation efficacy of wheat, mungbean and eggplant grown in soil spiked with polyaromatic hydrocarbons (PAH) was assessed in a pot experiment. The results of this study showed that Am inoculation enhanced dissipation amount of PAHs in planted soil, plant uptake PAHs, dissipation amount of PAHs in planted versus unplanted spiked soil and loss of PAHs by the plant-promoted biodegradation. A number of parameters were monitored including plant shoot and root dry weight, plant tissue water content, plant chlorophyll, root lipid content, oxido-reductase enzyme activities in plant and soil rhizosphere and total microbial count in the rhizospheric soil. The observed physiological data indicate that plant growth and tolerance increased with Am, but reduced by PAH. This was reflected by levels of mycorrhizal root colonization which were higher for mungbean, moderate for wheat and low for eggplant. Levels of Am colonization increased on mungbean > wheat > eggplant. This is consistent with the efficacy of plant in dissipation of PAHs in spiked soil. Highly significant positive correlations were shown between of arbuscular formation in root segments (A)) and plant water content, root lipids, peroxidase, catalase polyphenol oxidase and total microbial count in soil rhizosphere as well as PAH dissipation in spiked soil. As consequence of the treatment with Am, the plants provide a greater sink for the contaminants since they are better able to survive and grow.

• Preventive Nutrition and Food Science
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• 제9권2호
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• pp.121-125
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• 2004

Effects of chemical treatment with a citric acid solution or ozonated water on microbiological changes in lettuce and cabbage during storage were studied. Fresh lettuce and cabbage samples were cut into small pieces and treated by soaking in either ozonated water or a citric acid solution. After treatment, populations of total bacteria, yeast and mold, and E. coli were determined. Numbers of microorganisms increased during storage, but ozonated water and citric acid treatments retarded the increase in microbial growth. Among treatments, 1 % citric acid treatment was the most effective in terms of microbiological change and inhibition of polyphenoloxidase (PPO). For lettuce, citric acid treatment decreased the microbial growth overall by 1.5 log CFU/g and inhibited the PPO activity by 80%. These results indicate that chemical-treated lettuce and cabbage retained a better quality than those of the control during storage.

• KSBB Journal
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• 제13권5호
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• pp.469-476
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• 1998

Among 31 water-born microbial strains isolated from various sites in Korea, strain DJ-4 was selected as a test organism for toxicity measurements in that its growth was completely inhibited by the presence of 668.4 mg/L of chloroform and 297.5 mg/L of toluene in the liquid LB medium whereas others did not. It was observed that lag periods and specific growth rates of DJ-4 batch vial cultures were prolonged and decreased, respectively, by phenol, benzene, toluene, ethylbenzene, p-xylene, perchloroethylene, trichloroethylene, and chloroform at the concentrations between 3.6 and 417.8 mg/L. There changes were found to be linear with respect to the concentrations of the toxic compounds. From the first-order regression equations, 50% effective concentrations (EC50${\mu}$ for concentrations of toxic compounds causing 50% decrease of specific growth rates and EC50lag for 50% increase of length of lag periods) were calculated for each compounds. By comparing DJ-4 EC50${\mu}$ values with Daphnia LC50's from a literature for benzene, ethylbenzene, toluene, and trichloroethlyene, it was concluded that microbial specific growth could be a new, fast, and reliable parameter for toxicity tests.

• Ocean and Polar Research
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• 제39권4호
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• pp.245-255
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• 2017

There are a number of pieces of evidences that suggest a link between marine diatoms and microorganisms, but knowledge about related microbial communities is greatly lacking. The present study investigated the microbial community structures related to the growth of the marine diatom Cyclotella meneghiniana. We collected free-living bacteria (FLB) and particle-associated bacteria (PAB) at each growth stage (e.g., lag, exponential, stationary and death) of the diatom, and analyzed their bacterial 16S rDNA using pyrosequencing. Metagenomics analysis showed that community structures of FLB and PAB differed considerably with the progress of growth stages. FLB showed higher diversity than PAB, but variation in the different growth stages of C. meneghiniana was more evident in PAB. The proportion of the genus Hoeflea, belonging to the order Rhizobiales, was dominant in both FLB and PAB, and it gradually increased with the growth of C. meneghiniana. However, Enhydrobacter clade tended to considerably decrease in PAB. In addition, Marinobacter decreased steadily in FLB, but first increased and then decreased in PAB. These results suggest that Hoeflea, Enhydrobacter, and Marinobacter may be closely related to the growth of diatom C. meneghiniana.

• 한국환경생태학회지
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• 제29권2호
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• pp.279-291
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• 2015

This study analyzed the growth characteristics of multi-layer planted trees through their growth analysis and attempted to present a management strategy. The subject of research is the Citizen's Forest Area of Seoul Forest Park located in Seoul City. Field surveys were conducted three times over eight years from 2005 when the Seoul Forest Park was created through 2013. Labels were attached to all trees in the target area, and their species, height and DBH were investigated. To identify the growth differences by trees in each area, a detailed tree location map was drawn up for use in the analysis. To check soil health, soil organic matter, soil pH and soil microbial activities were analyzed. It turned out that the growth of the multi-layer planted trees in the target area of research was higher than that of the trees in existing urban parks, and that it was similar to that of trees in natural forests. Through a field survey in the area with a remarkably low growth, high-density planting problem, soil was found to have excess-moisture and there was the problem of Pueraria lobata covering. As a result of the analysis of the soil, it was found that its organic content in the soil was lower; soil pH was higher; and microbial activities in the soil were lower when compared to that of natural forests.

• Journal of Microbiology and Biotechnology
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• 제15권5호
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• pp.984-991
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• 2005

Soil or seed applications of plant growth-promoting rhizobacteria (PGPR) have been used to enhance growth of several crops as well as to suppress the growth of plant pathogens. In this study, we selected a PGPR strain, Paenibacillus polymyxa strain E681, out of 3,197 heat-stable bacterial isolates from winter wheat and barley roots. Strain E681 inhibited growth of a broad spectrum plant pathogenic fungi in vitro, and treatment of cucumber seed with E681 reduced incidence of damping-off disease caused by Pythium ultimum, Rhizoctonia solani, or Fusarium oxysporum. When inoculated onto seeds as vegetative cells or as endospores, E681 colonized whole cucumber root systems and root tips. Different temperatures such as $20^{\circ}C\;and\;30^{\circ}C$ did not affect root colonization by strain E681. This colonization was associated with a consistent increase in foliar growth of cucumber in the greenhouse. These results indicate that strain E681 is a promising PGPR strain for application to agricultural systems, particularly during the winter season.

• 한국환경복원기술학회지
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• 제26권2호
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• pp.13-24
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• 2023

Sewage sludge has been widely used as an organic fertilizer in agriculture. However, sewage sludge can cause serious malodor problems resulting from the decomposition of organic compounds in anaerobic conditions. The malodor of sewage sludge mainly occurs due to a low carbon to nitrogen ratio (C/N), high moisture, and low temperature, which are ideal conditions for ammonia emissions. Therefore, in this study, we investigated the reduction of the odor-causing ammonia nitrogen (NH₃-N) in sewage sludge by co-application of microbes and methanol (MeOH). The physico-chemical properties of the municipal sewage sludge showed that the odor was mainly caused by a higher NH₃-N content (2932.2 mg L^-1). Supplementation with MeOH (20%) as a carbon source in the sewage sludge significantly reduced the NH₃-N up to 34.2% by increasing C/N ratio. Furthermore, the sewage sludge was treated with the NH₃-N reducing and plant growth promoting (PGP) bacteria Stenotrophomonas rhizophila SRCM 116907. The treatment with S. rhizophila SRCM 116907 significantly increased the seedling vigor index of Lolium perenne (10.3%) and Chrysanthemum burbankii (42.4%). The findings demonstrate that supplementing sewage sludge with methanol significantly reduces ammonia emissions, thereby mitigating malodor problems. Overall, the study highlights the potential of using a microbial and methanol approach to improve the quality of sewage sludge as an organic fertilizer and promote sustainable agriculture.

• Asian-Australasian Journal of Animal Sciences
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• 제9권5호
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• pp.519-524
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• 1996

An investigation was carried out to study the microbial colonization and degradation of five crop residues, viz., sago waste, rice straw, oil palm trunk shavings, untreated palm press fibre and palm press fibre teated with 3% ammonium hydroxide in the rumen of goats. Colonisation by rumen bacteria and fungi was already established on all the five crop residues 8 h after incubation. However, the extent of colonization varied among the crop residues. Microbial colonization was poor on palm press fibre (treated and untreated) but more extensive on sago waste, oil palm trunk shavings and rice straw. By 24 h, most of the soft-walled tissues in sago waste, rice straw and oil palm trunk shavings were degraded leaving the thick-walled tissues extensively colonized by bacteria and fungi. Degradation on palm press fibre was still limited. At 48 h, the thick-walled tissues of sago waste, oil palm trunk shavings and rice straw showed various degrees of degradation - from small erosion zones to large digested areas. Bacterial growth was similar to that at 24 h but fungal growth was less. On palm press fibre, microbial colonization was more extensive than at 24 h but degradation of the fibres was still limited. Degradation of all the five crop residues at 72 h was somewhat similar to that at 48 h. Overall, microbial colonization and degradation were the most extensive on sago waste, followed by rice straw and oil palm trunk shavings, and the least on palm press fibre (treated and untreated). Dry matter loss of the five crop residues at the various incubation periods also showed the same order of degradation.