• 한국식품위생안전성학회:학술대회논문집
• /
• 한국식품위생안전성학회 2005년도 추계 국제심포지움 및 정기학술발표회
• /
• pp.159-173
• /
• 2005

• Food Science and Biotechnology
• /
• 제15권5호
• /
• pp.664-671
• /
• 2006

Modeling the growth kinetics of lactic acid bacteria (LAB), one of the most valuable microbial groups in the food industry, has been actively pursued in order to understand, control, and optimize the relevant fermentation processes. Most modeling approaches have focused on the development of single population models. Primary single population models provide fundamental kinetic information on the proliferation of a primary LAB species, the effects of biological factors on cell inhibition, and the metabolic reactions associated with cell growth. Secondary single population models can evaluate the dependence of primary model parameters, such as the maximum specific growth rate of LAB, on the initial external environmental conditions. This review elucidates some of the most important single population models that are conveniently applicable to the LAB fermentation analyses. Also, a well-defined mixed population model is presented as a valuable tool for assessing potential microbial interactions during fermentation with multiple LAB species.

• 대한환경공학회지
• /
• 제31권12호
• /
• pp.1069-1074
• /
• 2009

본 연구에서는 CuO와 ZnO의 입자 크기가 옥수수의 성장과 토양 미생물 군집에 미치는 독성을 microcosm 실험을 통하여 살펴보았다. 나노 입자는 micro 입자에 비해 옥수수의 biomass를 약 30% 감소시켜 나노 입자가 옥수수의 성장을 저해하는 것으로 나타났다. 토양 미생물 활성 지표인 Dehydrogenase activity는 CuO 나노 입자에서는 낮게 나타났으나 ZnO 나노 입자에서는 높게 나타났다. Biolog test 결과, CuO 나노 입자와 ZnO micro 입자에서 토양 미생물 다양성이 감소하는 것으로 나타났다. 그러므로, metal oxide의 나노 입자가 micro 입자보다 항상 토양 미생물의 활성 및 다양성에 더 유해한 영향을 나타내는 것은 아니라고 판단된다.

• Biotechnology and Bioprocess Engineering:BBE
• /
• 제5권3호
• /
• pp.207-210
• /
• 2000

When endothelial cells isolated isolated from human umbilical venis were cultred for 6dary using 96-well microplates, the final cell density in each was fiund not to be the same although the medium composition of each well was exactly the same. Cell growth in the wells located at the periphery of a microplate was low, while that in the central area of the plate was high. A possible cause for different rate of growth was proposed as the uneven concentration of oxygen in the culture medium of each well.

• Journal of Applied Biological Chemistry
• /
• 제50권4호
• /
• pp.239-243
• /
• 2007

Effects of aqueous chlorine dioxide ($ClO_2$) treatment on the microbial growth and the quality of iceberg lettuce during storage were examined. Lettuce samples were treated with 0, 5, 10, and 50 ppm of $ClO_2$ solution and stored at $4^{\circ}C$. Aqueous $ClO_2$ treatment significantly decreased the populations of total aerobic bacteria, yeasts and molds, and coliforms on the shredded lettuce. Fifty ppm $ClO_2$ treatment reduced the initial populations of total aerobic bacteria, yeasts and molds, and coliforms by 1.77, 1.34, 1.10 log CFU/g, respectively. Aqueous $ClO_2$ treatment caused negligible changes in the Hunter color L, a, and b values during storage. Sensory evaluations exhibited that there were no significant changes among treatments. These results indicate that the aqueous $ClO_2$ treatment can be useful in improving the microbial safety of the iceberg lettuce during storage and extending the shelf life.

• Food Science and Biotechnology
• /
• 제16권6호
• /
• pp.1018-1022
• /
• 2007

Effect of aqueous chlorine dioxide treatment on the microbial growth and quality changes of strawberries during storage was examined. Strawberries were treated with 5, 10, and 50 ppm of chlorine dioxide solution, and stored at $4{\pm}1^{\circ}C$. Total aerobic bacteria in strawberries treated at 50 ppm of chlorine dioxide were increased from 1.40 to 2.10 log CFU/g after 7 days, while increasing in the control from 2.75 to 4.32 log CFU/g. Yeasts and molds in strawberries treated at 50 ppm of chlorine dioxide were increased from 1.10 to 1.97 log CFU/g after 7 days, while the control was increased from 2.55 to 4.50 log CFU/g. The pH and titratable acidity of strawberries were not significantly different among treatments. Sensory evaluation results showed that chlorine dioxide-treated strawberries had better sensory scores than the control. These results indicate that chlorine dioxide treatment could be useful in improving the microbial safety and qualities of strawberries during storage.

• 상하수도학회지
• /
• 제23권2호
• /
• pp.175-180
• /
• 2009

This study was conducted to improve biological degradation efficiency of toluene as a model volatile organic compound (VOC) using yeast Candida tropicalis and to suggest an effective method for bioreactor operation. The yeast strain was immobilized with polyethylene glycol (PEG), alginate, and powdered activated carbon (PAC). The yeast-immobilized polymer media were used as fluidized materials in an airlift bioreactor. Polymer media without PAC were also made and operated in another airlift bioreactor. The two bioreactors showed toluene removal efficiencies ranging 80-96% at loading rates of $10-35 g/m^3-hr$, and the bioreactor containing the polymer media with PAC achieved higher removal efficiency. Protein contents in the liquid phase showed that the bioreactor using the yeast-immobilized polymer media with PAC had a higher rate of microbial growth initially than that without PAC. In addition, the microbial growth rate inside of the polymer media with PAC was five times higher than that without PAC. Consequently, the polymer media containing the yeast strain and PAC could enhance removal efficiencies for VOCs, and the immobilization method improve microbial activity and stability for a long-term operation of biological systems.

• Environmental Engineering Research
• /
• 제12권4호
• /
• pp.129-135
• /
• 2007

This study evaluated microbial risk that could develop within soil microbial communities after amended with organic fertilizers from stabilized swine manure waste. For this purpose, we assessed the occurrences and competitiveness of antibiotic resistance and pathogenicity in soil microbial communities that were amended with swine manure wastes stabilized by a traditional lagoon fermentation process and an autothermal thermophilic aerobic digestion process, respectively. According to laboratory cultivation detection analysis, soil applications of the stabilized organic fertilizers resulted in increases in absolute abundances of antibiotic resistant bacteria and of two tested pathogenic bacteria indicators. The increase in occurrences might be due to the overall growth of microbial communities by the supplement of nutrients from the fertilizers. Meanwhile, the soil applications were found to reduce competitiveness for various types of antibiotic resistant bacteria in the soil microbial communities, as indicated by the decrease in relative abundances (of total viable heterotrophic bacteria). However, competitiveness of pathogens in response to the fertilization was pathogens-specific, since the relative abundance of Staphylococcus was decreased by the soil applications, while the relative abundance of Salmonella was increased. Further testes revealed that no MAR (multiple antibiotic resistance) occurrence was detected among cultivated pathogen colonies. These findings suggest that microbial risk in the soil amended with the fertilizers may not be critical to public health. However, because of the increased occurrences of antibiotic resistance and pathogenicity resulted from the overall microbial growth by the nutrient supply from the fertilizers, potential microbial risk could not be completely ruled out in the organic-fertilized soil samples.

• 한국토양비료학회지
• /
• 제34권1호
• /
• pp.8-16
• /
• 2001

미생물제 비료시용이 배추의 생육과 토양의 화학성 변화 및 미생물상에 미치는 영향을 포장시험으로 실시하였다. 대조구에 비하여 TLB미생물제 비료를 시용함으로써 배추의 생육은 양호하였으며, 배추수량에 있어서도 유의성 있는 증수 효과를 보였다. 그러나 TLB미생물제 비료를 시용하더라도 배추생육시 요소비료의 추비량 및 퇴비 시용량을 줄일 경우에는 대조구에 비하여 수량이 다소 감소하는 경향을 보였다. 토양의 화학적 성질에 미치는 TLB 미생물제 비료 시용의 효과는 대조구에 비하여 수확기의 토양유기물 함량의 감소가 가장 큰 것으로 나타났고, 토양중 전질소 함량은 0.76~1.44% 범위로 대조구보다 오히려 미생물제 비료 시용구가 감소하는 경향을 보였다. 토양중 유효인산 함량은 시험전 토양의 559ppm에 비하여 배추의 수확기에 대조구 755ppm 그리고 미생물제 시용구 653ppm으로 대조구와 비교하여 미생물제 시용으로 인하여 다소 낮은 편이었다. 한편 배추 수확 후 배추의 화학적 성분은 전 질소 2.62~2.94%, 인산 1.48~1.55%, 칼리 3.60~4.38%범위이었으며, 각 처리간에 함량의 뚜렷한 차이는 없었다. 토양 미생물상중 전세균수는 대조구보다 미생물제 시용으로 다소 감소하였으나, 배추수확기 토양에서 Pseudomonas속이 3배 이상 높은 군락을 보였다. 그러나 방선균은 큰 차이를 보이지 않았지만, 사상균수는 수확기 토양에서 미생물제 비료 시용으로 현저히 높은 군락을 형성하였다.

• Asian-Australasian Journal of Animal Sciences
• /
• 제11권6호
• /
• pp.661-672
• /
• 1998

Two experiments were conducted to examine the effects of a range of concentrations of ruminal fluid ammonia ($NH_3$-N) on forage digestibility, microbial growth efficiency and the mix of microbial species. Urea was either continuously infused directly into the rumen of sheep fed 33.3 glh of oaten chaff (Exp. I) or sprayed onto the oaten chaff (750 g/d) given once daily (Exp. 2). Concentrations of $NH_3$-N increased with incremental addition of urea (p < 0.01). Volatile fatty acids (VFA) concentrations and 24 h in sacco organic matter digestibility in the rumen were higher when supplemental urea was given (p < 0.01). The (C2 + C4) : C3 VFA ratio was lower (p < 0.05) when $NH_3$-N was above 200 mgN/I. The fungal sporangia appearing on oat leaf blades were significantly higher when urea was supplemented, indicating that $NH_3$-N was a growthlimiting nutrient for fungi at levels of $NH_3$-N below 30 mgN/l. The density of protozoa was highest when $NH_3$-N concentrations were adjusted to 30 mgN/I for continuously fed ($4.4{\times}10^5/ml$) and to 168 mgN/1 for once daily feeding ($2.9{\times}10^5/ml$). Thereafter increasing concentrations of $NH_3$-N, were associated with a concomitant decline in protozoal densities. At the concentration of $NH_3$-N above 200 mgN/l, the density of protozoa was similar to the density of protozoa in ruminal fluid of the control sheep ($1.8{\times}10^5/ml$). The efficiency of net microbial protein synthesis in the rumen calculated from purine excretion was 17-47% higher when the level of $NH_3$-N was above 200 mgN/1. The possibilities are that 1) there is less bacterial cell lysis in the rumen because of the concomitant decrease in the protozoal pool and/or 2) microbial growth per se in the rumen is more efficient with increasing $NH_3$-N concentrations.