• Journal of Microbiology and Biotechnology
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• v.19 no.12
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• pp.1603-1611
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• 2009

High-cell-density cultivation of yeast was investigated using the agricultural waste products corn steep liquor (CSL) and molasses. The Saccharomyces cerevisiae KV-25 cell mass was significantly dependent on the ratio between C and N sources. The concentrations of molasses and CSL in the culture medium were statistically optimized at 10.25% (v/v) and 16.87% (v/v), respectively, by response surface methodology (RSM). Batch culture in a 5-l stirred tank reactor using the optimized medium resulted in a cell mass production of 36.5 g/l. In the fed-batch culture, the feed phase was preceded by a batch phase using the optimized medium, and a very high dried-cell-mass yield of 187.63 g/l was successfully attained by feeding a mixture of 20% (v/v) molasses and 80% (v/v) CSL at a rate of 22 ml/h. In this system, the production of cell mass depended mainly on the agitation speed, the composition of the feed medium, and the glucose level in the medium, but only slightly on the aeration rate.

• Journal of Microbiology and Biotechnology
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• v.8 no.1
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• pp.8-13
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• 1998

Animal cells in culture typically convert most of the glucose they consume into lactate. The accumulation of lactate, however, is commonly cited as one of the factors that inhibit cell growth and limit the maximum cell concentration that can be achieved in culture. The specific production of lactate and the amount of glucose converted to lactate can be reduced when cells are grown in a fed-batch culture in which the residual glucose concentration is maintained at low levels. Such a fed-batch culture was used to grow and adapt hybridoma cells into a low-lactate-producing state before changing into continuous culture. The cells reached and maintained a high viable cell concentration at steady state. In a similar manner, cells that were initially grown in batch culture and a glucose-rich environment reached a steady state with a cell concentration that is much lower. The feed composition and dilution rates for both cultures were similar, suggesting steady state multiplicity. From a processing perspective the desired steady state among those is the one with the least metabolite production. At such seady state nutrient concentration in the feed can be further increased to increase cell and product concentrations without causing the metabolite inhibitory effect typically seen in a cell culture. Controlling cell metabolism in a continuous culture to reduce or eliminate waste metabolite production may significantly improve the productivity of mammalian cell culture processes.

• Journal of Environmental Science International
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• v.29 no.10
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• pp.1011-1014
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• 2020

The purpose of this study was to investigate the egg freshness and eggshell characteristics of old laying hens by adding sea urchin shell powder to the feed of such hens to achieve the objectives continuously pursued by environmental management, such as business profitability and waste resource utilization. A total of 90 Hy-Line Brown layers (66 weeks of age) were randomly divided into 2 treatments with 3 replicates, each of which consisted of 15 older layers, for 4 weeks. These treatments included a control (i.e., 0%) and 2% sea urchin shell powder. The 2% supplementation of sea urchin shell powder increased the Haugh unit (HU) at 2 and 4 weeks and eggshell strength at 4 wks compared to the controls (p<0.05). The HU at 0 weeks, eggshell thickness from 0 through 3 weeks, and eggshell strength at 0 and 2 weeks were not different between treatments (p>0.05). These results suggest that the addition of 2% sea urchin powder to the feed of laying hens improves egg freshness and eggshell strength in old laying hens.

• Asian-Australasian Journal of Animal Sciences
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• v.23 no.2
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• pp.279-286
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• 2010

Livestock production in Vietnam is, as in most Asian countries, increasing rapidly and changing into specialized highly intensified operations. The volume of animal excreta generated exceeds the capacity of the operation land base and cannot be utilized efficiently. As a consequence, there is a loss of plant nutrients from livestock farms that causes environmental pollution. This study carried out a feed and excretion experiment measuring fecal characteristic, daily fecal production, daily nitrogen and phosphorous excretion from grower-finisher pigs fed prevalent rations in Vietnam. Furthermore, equations for assessing the excretion were tested, which can be used in farm models for optimal recycling of manure while focusing on reducing pollution. The results indicated that fecal production and nutrient excretion were affected by the different rations tested. This study showed that five selected equations for predicting excretion from grower-finisher pigs in Danish conditions can also be used with precision in Vietnamese pig farming systems. The equations have been proven valid and can, therefore, be used as a much needed tool for assessing fecal production and nitrogen in excreta on pig farms. The study also showed that about 12% of nitrogen excreted was emitted during housing. Waste water contains more than half of the nitrogen excreted, mainly in ammonium form which has a high potential for gaseous emission.

• The Korean Journal of Mycology
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• v.23 no.4 s.75
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• pp.354-358
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• 1995

A yeast loading biochemical oxygen demand (BOD) sensor was designed and constructed to quickly measure the concentration of biologically assimilable organic substances dissolved in water as BOD values to feed back to the waste water treating processes. The sensitivity of the BOD sensor reached maximum at around pH 7.0 and $30^{\circ}C$ where yeast showed the highest assimilation activity. Biomass also affected the sensor output, and biomass of $ 0.14\;mg/cm^2$ on the dialysis membrane appeared to be the optimum cell mass level. The sensitivity of the sensor depended on the kinds of pollutants and increased considerably when the yeast was preincubated in the solution of respective pollutants before loading on the sensor.

• Korean Journal of Poultry Science
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• v.46 no.2
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• pp.87-94
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• 2019

Huge amount of persimmon peels, which are byproducts usually arising after making dried persimmons from fresh persimmons, are generated in fall, every year. As the dry matter of persimmon peel contains carbohydrates over 80%, it could be a good candidate for feed. In this study, we evaluated the persimmon peel as a feed resource for a hen laying eggs. Persimmon peel has lower ratio of crude protein and fat composition while higher ratio of crude fiber composition compared to a basal laying hen feed. Feeding the persimmon peel by adding to the feed at the level of 2% or 5% did not affect the egg-laying rate from beginning to the peak of laying. In addition, feeding the persimmon peel did not affect the egg quality either, as the pH, Haugh unit, yolk color and shell thickness of the egg were not different from each other. The composition of amino acids and fatty acids were also almost same for each other, except for the linolenic acid which was slightly higher in the persimmon peel feeding groups. In conclusion, addition of persimmon peel to the feed up to 5% might be helpful to increase the income and reduce the waste produced from the agricultural byproduct.

• Journal of Fisheries and Marine Sciences Education
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• v.27 no.2
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• pp.566-575
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• 2015

The study aims to identify the generation and treatment of fishery by-products in Korea and suggests future directions and strategies for their eco-friendly utilization and industrialization. First, the study focuses on the identification of the generation and their treatment in Korea since merely few study were conducted and they did not provide enough information regarding the overall generation and treatment at the national level. According to the estimation, Korea generates 800 thousand to 1,200 thousand tones of fishery by-product every year. The fishery by-products generated at large seafood markets and processing facilities are used or processed as fish meal and feed, but those generated from households and small seafood restaurants are currently treated as food waste. In addition, inadequately treated fishery by-products cause various problems such as spoiling urban landscape, creating odor and incubating pest. After identifying the generation and treatment of fishery by-products, the study suggests directions for the formulation of infrastructure for transition into resource circulation society, minimization of dumped waste and their eco-friendly recycling as resources, diversification of recycled goods and development into a high-value added industry. Finally, the study suggests detailed strategies for the directions such as establishment of legal and institutional foundation, separation of fishery by-products from wastes, development of technology tailored for commercialization, introduction of pilot projects for industrialization and cultivation of social enterprises.

• Economic and Environmental Geology
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• v.37 no.1
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• pp.113-119
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• 2004

Mineral wastes are generated by the minerals, mining, and metal industries. These are generally inorganic waste streams of mainly waste rock or residues from refining during extraction of metals or minerals from the ore. There are many plants where minerals are recovered in secondany circuits, treating tailings, where the feed grades are much lower than would be economic on a mined ore. The world is now becoming aware of the finite nature of its resources at a price, and of the ever-increasing development costs of large new mines. Reprocessing of old tailings on a large scale must be worth examining very seriously by those with access to sufficient material of this type. In the present paper, mineral separation techniques to recover valuable metals and resources from the old tailings are reviewed, and new trends for future developments are also discussed.

• Journal of Wetlands Research
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• v.14 no.3
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• pp.365-374
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• 2012

Due to the wide use of feed additives on pig farms, large content of heavy metals and antibiotics have been found in piggery wastes. More than 90 % of piggery wastes were applied to crop field in Korea. The metals and antibiotics originated from piggery waste in the soil may affect plant growth and human health. To examine the adsorption capacity and residual ratio of heavy metals and antibiotics to the soil, a couple of jar test and leaching tests were conducted. While 86.4 % of zinc and 68% of copper applied were adsorbed to soil particles, while over than 60% of antibiotics in pig manure liquid fertilizer were leaked out to effluent.

• Journal of Microbiology and Biotechnology
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• v.1 no.3
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• pp.212-219
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• 1991

Four species of yeast, Saccharomyces cerevisiae, Candida utilis, Saccharomycopsis flbuligera, and Schwanniomyces castellii were evaluated for their ability to bioconvert potato processing waste water into microbial protein and the resulting single-cell proteins were evaluated as protein sources for rainbow trout, using in vitro analyses. The studies indicated that Schwanniomyces castellii, which utilizes starch dircetly and converts it into cell mass efficiently, was suitable for the bioconversion. In the single-stage continuous bioconversion, the yield S. castellii cell mass, which contained approximately 37% protein, was 77%, at dilution rate 0.25 $h^{-1}$. Reduction of total carbohydrate was 81%. During batch fermentations, cell mass yield was about 72% and total carbohydrate reduction was 81%. Among the yeasts tested, S. castellii possessed the most fragile cell wall and had a favorable amino acid profile for salmonid fish; protein score of 86% (Met). In an in vitro pepsin digestibility test 80% digestibility (23~38% above control) was observed when cells were pre-heated in a steam bath for 30 min. Results presented should be regarded as being preliminary in nature because they were derived from single experiments.