• Journal of Microbiology and Biotechnology
• /
• 제33권4호
• /
• pp.419-429
• /
• 2023

Ultraviolet C (UV-C, 200-280 nm) light has germicidal properties that inactivate a wide range of pathogenic and spoilage microorganisms. UV-C has been extensively studied as an alternative to thermal decontamination of fruit juices. Recent studies suggest that the efficacy of UV-C irradiation in reducing microorganisms in fruit juices is greatly dependent on the characteristics of the target microorganisms, juice matrices, and parameters of the UV-C treatment procedure, such as equipment and processing. Based on evidence from recent studies, this review describes how the characteristics of target microorganisms (e.g., type of microorganism/strain, acid adaptation, physiological states, single/composite inoculum, spore, etc.) and fruit juice matrices (e.g., UV absorbance, UV transmittance, turbidity, soluble solid content, pH, color, etc.) affect the efficacy of UV-C. We also discuss the influences on UV-C treatment efficacy of parameters, including UV-C light source, reactor conditions (e.g., continuous/batch, size, thickness, volume, diameter, outer case, configuration/arrangement), pumping/flow system conditions (e.g., sample flow rate and pattern, sample residence time, number of cycles), homogenization conditions (e.g., continuous flow/recirculation, stirring, mixing), and cleaning capability of the reactor. The collective facts indicate the immense potential of UV-C irradiation in the fruit juice industry. Existing drawbacks need to be addressed in future studies before the technique is applicable at the industrial scale.

• KSBB Journal
• /
• 제14권2호
• /
• pp.181-187
• /
• 1999

젖산 생산에 큰 비중을 차지하는 원료비용 절감을 위한 다양한 공업적 질소원의 이용 가능성을 조사하였다. CSL를 사용하여 회분 발효한 결과, CSL 5%배지 발효시 높은 생산성을 보였으며, 정제 CSL을 사용한 배지에서 젖산 생산성은 CSL보다 약 1.21 배 증가율을 보였다. Yeast extract와 CSL 혼합질소원의 배지조성을 변화시켜 LBM5의 젖산 생성정도를 알아본 결과, 조성 비율 1:8일 때 우수한 발효율을 관찰 할 수 있었다. 발효 폐기물의 대체 질소원 사용가능성을 조사하기 위하여 맥주공장에서 부산물로 배출되는 폐효모를 이용하여 발효시에도 CSL 5%와 비슷한 발효율을 얻었다 연속발효 수행결과, 최적의 희석율은 0.05-0.065-1h였으며 젖산 생산성에 있어서 회분발효보다 1.93.0배증가하였다. 한편 초기 순수배지에 들어가는 yeast extract양의 1/3-2/3를 발효폐액에 첨가하여 회분발효 및 연속발효 실험을 수행하여 높은 젖산 생산성을 얻으므로써 공정상 원료비 절감효과를 기대할 수 있어으며 잔류 영양분을 재사용함으로써 폐액량 감소에 따른 처리비용 절감이라는 이중적인 효과를 얻게 되었다.

• 대한물리의학회지
• /
• 제14권4호
• /
• pp.19-27
• /
• 2019

PURPOSE: This study examined which stretching exercise had the most positive effect on increasing the range of motion (ROM) of the knee joint in healthy people and whether there was a difference between continuous stretching and intermittent stretching. METHODS: This study included 30 healthy university students from OOO University. The subjects were asked to sit on a mat and perform hamstring-stretching exercise during which the ROM and muscle tone were measured with pre and post-tests. Each subject was assigned randomly to a continuous stretching group (stretching without relaxation time group, n=10, G1) or intermittent stretching group (stretching with 10s relaxing time group, n=10, G2; and stretching with 20s relaxing time group, n=10, G3). The participants conducted hamstring stretching exercises with a sit-and-reach box at three different rest times (0s, 10s, and 20s). Subsequently, they underwent passive knee extension (PKE) tests, in which the ROM of the knee joint was measured with a goniometer, and the muscle tone was evaluated using a MyotonPro. RESULTS: Significant differences in muscle tone, stiffness, and ROM were observed between pre-test and post-test in each groups (p<.05). Although the post hoc tests indicated no significant differences in muscle tone and ROM between the continuous stretching group and intermittent stretching group (p>.05), the rate of change of the ROM showed that the intermittent stretching group developed more effective maintenance of the hamstring flexibility. CONCLUSION: No significant differences in the muscle tone of the hamstring and ROM of the knee joint were observed according to the hamstring stretching exercises with three different rest times. On the other hand, the rate of change of the ROM showed that intermittent stretching maintained the hamstring flexibility more effectively.

• Journal of Microbiology and Biotechnology
• /
• 제17권7호
• /
• pp.1221-1225
• /
• 2007

A ${\beta}$-ionone-resistant mutant strain isolated from the red yeast Xanthophyllomyces dendrorhous KCTC 7704 was used for batch and continuous fermentation kinetic studies with glucose media in a 2.5-1 jar fermentor at $22^{\circ}C$ and pH 4.5. The kinetic pattern of growth and carotenoid concentration in the batch fermentations exhibited a so-called mixed-growth-associated product formation, possibly due to the fact that the content of intracellular carotenoids depends on the degree of physical maturation toward adulthood. To determine the maximum specific growth rate constant (${\mu}_m$) and Monod constant ($K_s$) for the mutant, glucose-limited continuous culture studies were performed at different dilution rates within a range of $0.02-0.10\;h^{-1}$. A reciprocal plot of the steady-state data (viz., reciprocal of glucose concentration versus residence time) obtained from continuous culture experiments was used to estimate a ${\mu}_m$ of $0.15\;h^{-1}$ and $k_s$ of 1.19 g/l. The carotenoid content related to the residence time appeared to assume a typical form of saturation kinetics. The maximum carotenoid content ($X_m$) for the mutant was estimated to be $1.04\;{\mu}g/mg$ dry cell weight, and the Lee constant ($k_m$), which was tentatively defined in this work, was found to be 3.0 h.

• 한국환경농학회지
• /
• 제42권4호
• /
• pp.435-443
• /
• 2023

Global concern over climate change, driven by greenhouse gas emissions, has prompted widespread interest in sustainable solutions. In the agricultural sector, biochar has emerged as a focal point for mitigating these emissions. This study investigated the impact of continuous biochar application on CO₂ and N₂O emissions during the spring cabbage cultivation period. Greenhouse gas emissions in the biochar treatment groups (soils treated with 1, 3, and 5 tons/ha of rice husk biochar) were compared to those in the control group without biochar. During the spring cabbage cultivation period in 2022, the total CO₂ emissions were in the range of 71.6-119.0 g/m² day, and in 2023, with continuous biochar application, they were in the range of 71.6-102.1 g/m² day. The total emissions of N₂O in 2022 and 2023 were in the range of 11.7-23.7 and 7.8-19.9 g/m² day, respectively. Overall, greenhouse gas emissions decreased after biochar treatment, confirming the positive influence of biochar on mitigating greenhouse gas release from the soil. Nevertheless, further research over an extended period exceeding five years is deemed essential to delve into the specific mechanisms behind these observed changes and to assess the long-term sustainability of biochar's impact on greenhouse gas dynamics in agricultural settings.

• Current Research on Agriculture and Life Sciences
• /
• 제4권
• /
• pp.127-131
• /
• 1986

정상사료내의 지질에 철분이 어떤 영향을 미치는가를 알아보기 위하여 정상사료(Common feed)와 물을 혼합한 비정상 사료내에 Vitamin E와 유리 불포화 지방산 함량을 측정한 결과 다음과 같은 성적을 얻었다. 1. 정상사료(P<.05)와 비정상사료(P<.01)내의 Vitamin E 함량은 1.75mg/g(실험 1일째) 로부터 0.25mg/g(실험 11일째)로 지속적으로 감소되었다. 2. 정상사료내의 유리 불포화 지방산 함량은 23.8mg/g(대조군)로부터 17.6mg/g(20% 철분 혼합군)로 역시 지속적으로 감소되었다(P<.01). 3. 비정상사료내의 유리 불포화 지방산 함량은 23.9mg/g(대조군)로부터 17.4mg/g(20% 철분 혼합군)로 지속적으로 감소되었다(P<.01). 4. 정상사료내의 Vitamin E와 유리 불포화 지방산 함량은 비정상사료내의 함량보다 다소 높았으나 유의차는 인정되지 않았다. 5. 정상사료와 비정상사료내의 Vitamin E와 유리불포화 지방산에 있어서 날짜 경과별 및 철분 혼합 수준별 간의 상호작용이 인정되었다.

• 전산구조공학
• /
• 제19권2호
• /
• pp.64-70
• /
• 2006

• East Asian mathematical journal
• /
• 제12권2호
• /
• pp.263-268
• /
• 1996

• 한국미생물·생명공학회지
• /
• 제14권2호
• /
• pp.193-198
• /
• 1986

Sacch. cerevisiae var. ellipsoideus 균주를 이용산업용 천연맥즙배지를 사용한 알콜연속 발효시 Hollow Fiber Recycle Reactor를 of용 Cell Recycle을 시켜 발효조내의 알콜 생산성을 높이기 위해 본 실험을 실시하였으며, 특히 Batch식과 연속발효시 HFR유무에 따른 특성을 비교 검토한 결과를 요약하면 다음과 같다. 1 Dilution rate가 0.1h$^{-1}$일때 11$^{\circ}$P 및 15$^{\circ}$P media를 이용한 알콜 연속발효에서 알콜농도는4.71% 및 5.82%(v/v) 이었으며 이때의 발효율은 각각 86.2%와 78.6 % 이었다. 2. HFR연속발효에서 D=0.1h$^{-1}$일때 알콜농도는 7.64% (v/v)로 높았으며, 이때의 생산성은 6.1g/l/h이었다. 또한 D=0.2h$^{-1}$일때 알콜농도와 생산성은 각각 7.62%(v/v) 및 12.2g/l/h/이었다. 3. HFR연속발효에서 D=0.3h$^{-1}$일때 알콜농도가 7.54% (v/v) 이었으며 알콜생산성은 18.1g/l/h 이었다. 4 알콜 생산성 비교에서 HFR 연속발효는 연속발효에 비해 4배의 증가효과가 있었으며 Batch발효에 비해서는 16.3배나 크게 증가하였다.

• ALGAE
• /
• 제35권3호
• /
• pp.277-292
• /
• 2020

Omega-3 fatty acids, including eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), are polyunsaturated fatty acids beneficial to human health. A limited number of microalgae have been used for commercial omega-3 production, which necessitates the identification of new microalgae with high omega-3 contents. We explored the fatty acid composition and EPA and DHA contents of the mixotrophic dinoflagellate Gymnodinium smaydae fed with the optimal algal prey species Heterocapsa rotundata. Cells of G. smaydae were found to be rich in omega-3 fatty acids. In particular, the DHA content of G. smaydae was 21 mg g^-1 dry weight, accounting for 43% of the total fatty acid content. The percentage of DHA in the total fatty acid content of G. smaydae was the highest among the reported microalgae except for Crypthecodinium cohnii. Moreover, to determine if the prey supply interval affected the growth rate of G. smaydae and its fatty acid content, three different prey supply intervals (daily, once every 2 d, and once for 4 d) were tested. Daily prey supply yielded the highest total fatty acid and DHA contents in G. smaydae. Furthermore, we successfully produced high-density G. smaydae cultures semi-continuously for 43 d with daily prey supply. During the semi-continuous cultivation period, the highest density of G. smaydae was 57,000 cells mL^-1, with an average growth rate of 0.7 d^-1. Taken together, the percentage of EPA and DHA in the total fatty acid content was maintained in the range of 54.2-56.9%. The results of this study support G. smaydae as a promising microalgal candidate for commercial DHA production and demonstrate that daily supply of prey can efficiently produce high-density G. smaydae cultures for more than a month.