• Microbiology and Biotechnology Letters
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• v.15 no.5
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• pp.334-339
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• 1987

Enzymatic conversion of pyruvic acid produced by microorganism to tryptophan was investigated. A luminescent bacteria. Beneckea sp., was used for the production of pyruvic acid. As a source of tryptophanase which synthesizes tryptophan from pyruvic acid, indole and ammonia, whole cells of Enterobacter aerogenes ATCC 10031 were used directly in the reaction mixture. To increase the production of tryptophan, nonionic detergents and nonaqeous organic solvents were used ms reserviors of indole in the reaction mixture. In the case of nonionic detergents, TritonX-100 was very effective. When 1.5% of Triton X-100 was used, 7.7g/$\ell$ of tryptophan was produced at 37$^{\circ}C$ for 48hr. In the case of nonaqueous solvents, 8.7g/$\ell$ of tryptophan was produced at 37$^{\circ}C$ for 48 hr, when 10% of benzene was used. This amount of tryptophan corresponds to conversion of 48% of Indole and 36% of pyruvic acid, respectively.

• The Journal of the Korea Contents Association
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• v.19 no.6
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• pp.160-167
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• 2019

This study was conducted to investigate the effect of initial ripening condition placed within a kimchi refrigerator and this result will be used as basic data for the development of fermentation system of Kimchi refrigerator. Hardness significantly decreased as the storage period longer. Lactic acid and Lactobacillus spp. showed a large amount until 8 weeks, but one without initial ripening contained much lower. The content of lactic acid bacteria increased from 4.50 logCFU/mL to 6.70 ~ 7.47 logCFU/mL and decreased to 5.08 ~ 6.10 logCFU/mL according to storage period. Consumer preferred $15^{\circ}C/52h$ samples rather than others in two weeks. $15^{\circ}C/36h$ and $6^{\circ}C/113h$ samples were significantly preferred during the whole storage period. These results indicate that the initial fermentation conditions affect the taste and fermentation degree of kimchi during the storage period.

• Asian-Australasian Journal of Animal Sciences
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• v.14 no.6
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• pp.880-884
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• 2001

Rumen microbiology research has undergone several evolutionary steps: the isolation and nutritional characterization of readily cultivated microbes; followed by the cloning and sequence analysis of individual genes relevant to key digestive processes; through to the use of small subunit ribosomal RNA (SSU rRNA) sequences for a cultivation-independent examination of microbial diversity. Our knowledge of rumen microbiology has expanded as a result, but the translation of this information into productive alterations of ruminal function has been rather limited. For instance, the cloning and characterization of cellulase genes in Escherichia coli has yielded some valuable information about this complex enzyme system in ruminal bacteria. SSU rRNA analyses have also confirmed that a considerable amount of the microbial diversity in the rumen is not represented in existing culture collections. However, we still have little idea of whether the key, and potentially rate-limiting, gene products and (or) microbial interactions have been identified. Technologies allowing high throughput nucleotide and protein sequence analysis have led to the emergence of two new fields of investigation, genomics and proteomics. Both disciplines can be further subdivided into functional and comparative lines of investigation. The massive accumulation of microbial DNA and protein sequence data, including complete genome sequences, is revolutionizing the way we examine microbial physiology and diversity. We describe here some examples of our use of genomics- and proteomics-based methods, to analyze the cellulase system of Ruminococcus flavefaciens FD-1 and explore the genome of Ruminococcus albus 8. At Illinois, we are using bacterial artificial chromosome (BAC) vectors to create libraries containing large (>75 kbases), contiguous segments of DNA from R. flavefaciens FD-1. Considering that every bacterium is not a candidate for whole genome sequencing, BAC libraries offer an attractive, alternative method to perform physical and functional analyses of a bacterium's genome. Our first plan is to use these BAC clones to determine whether or not cellulases and accessory genes in R. flavefaciens exist in clusters of orthologous genes (COGs). Proteomics is also being used to complement the BAC library/DNA sequencing approach. Proteins differentially expressed in response to carbon source are being identified by 2-D SDS-PAGE, followed by in-gel-digests and peptide mass mapping by MALDI-TOF Mass Spectrometry, as well as peptide sequencing by Edman degradation. At Ohio State, we have used a combination of functional proteomics, mutational analysis and differential display RT-PCR to obtain evidence suggesting that in addition to a cellulosome-like mechanism, R. albus 8 possesses other mechanisms for adhesion to plant surfaces. Genome walking on either side of these differentially expressed transcripts has also resulted in two interesting observations: i) a relatively large number of genes with no matches in the current databases and; ii) the identification of genes with a high level of sequence identity to those identified, until now, in the archaebacteria. Genomics and proteomics will also accelerate our understanding of microbial interactions, and allow a greater degree of in situ analyses in the future. The challenge is to utilize genomics and proteomics to improve our fundamental understanding of microbial physiology, diversity and ecology, and overcome constraints to ruminal function.

• Journal of Pharmaceutical Investigation
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• v.33 no.2
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• pp.145-149
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• 2003

Manufacturing facilities of the pharmaceuticals must meet certain level of the cleanness required so that foreign substances such as dust, moisture, heat, microorganism, or virus do not contaminate the product. In case of radiopharmaceuticals for medical treatment and diagnosis, not only should the operators and environment be protected from radiation but also need to be isolated from the foreign contaminant. Therefore, manufacturing facilities for radiopharmaceuticals must satisfy the design standards of both hot cell and clean room which are specified by GMP. However, standards of maintaining negative pressure for preventing spread of radioactive contaminant in isolated facilities conflict with the standards of maintaining positive pressure for keeping cleanness. To solve this problem, air pressure of hot cell was designed lower than in the adjacent area to meet standards of the radiation safety. To keep higher cleanness in certain part of the hot cell for filling, minimal relative positive pressure allows. In order to effectively maintain the cleanness that is required for production of Tc-99m generator, which takes 70% of whole demand of radiopharmaceuticals, the rooms placed in each side of production room are used as a buffer area and three lead hot cells are installed in production room. In this research, we established the appropriate engineered design concept for Tc-99m generator manufacturing facility, which satisfies both GMP cleanness standard for preventing particles, bacteria, other contaminants and the regulations of radiation safety for supervising and controlling the amount of radiation exposure and exhausted radioactivity. And the concept of multi-barrier buffer zones is introduced to apply negative air pressure for hot cell with first priority and to continue relative positive air pressure for clean room.

• Journal of Food Hygiene and Safety
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• v.37 no.2
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• pp.107-113
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• 2022

A number of studies have been conducted to confirm the preventive effect of xylitol on dental caries as a whole or partial alternative to dietary sugars. This study reviewed the oral health effects of xylitol on the prevention mechanism of dental caries, the prevention of dental caries, the inhibition of mother-to-child transmission, and the oral health effects in the elderly based on existing studies on the oral health of xylitol. Carbohydrates and dietary sugars in food are fermented by acid-producing microorganisms in the mouth and produce dental plaque and acid, which cause dental caries. However, most dental decay-causing bacteria cannot produce acids by metabolizing xylitol. Xylitol, stored in cells as a non-metabolizable metabolite by Streptococcus mutans (S. mutans), affects bacterial glucose metabolism and inhibits bacterial growth. Xylitol consumption also reduces the amount of plaque and the population of S. mutans in both plaque and saliva. In addition, xylitol acts in the remineralization process. Xylitol has been confirmed to effectively prevent dental caries, inhibit mother-to-child transmission of MS, prevent dental caries, and increase salivary flow in the elderly. In conclusion, xylitol is an adequate sugar substitute for dental health, from infants to the elderly. For future studies, the researchers recommend reviewing the effects of xylitol on the oral and intestinal microbial environment and the side effects of excessive intake.

• Journal of the Korean Society of Food Science and Nutrition
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• v.34 no.10
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• pp.1579-1585
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• 2005

The aim of this study was to propose utilization of tofu whey concentrates separated by ultrafiltration (UF) for yogurt production. The curd yogurt was prepared from whole milk added with skim milk Powder in which UF powder was substituted 0$\%$, 6.25$\%$, 12.5$\%$ or 25$\%$ for skim milk powder. The quality characteristics of yogurt in terms of pH, titratable acidity, viscosity, color and viable cell counts were evaluated. There were no significant differences in pH and titratable acidity between control (yogurt added with only skim milk powder) and yogurt added with UF powder after 24 hr of fermentation at 37$^{\circ}C$. Apparent viscosity of yogurt added with UF powder was lower (2,623 $\∼$ 3,189 cps) than that of the control yogurt (3,196 cps). Lightness and redness value of yogurt added with UF powder were not significantly different from control yogurt, while yellowness value increased as the amount of UF powder increased. Addition of UF powder stimulated the growth of lactic acid bacteria. Gas chromatographic analysis detected acetaldehyde, diacetyl, and organic acids, and more volatile compounds were detected in yogurt added with UF powder. Sensory analysis showed that yogurt added with UF powder were evaluated as acceptable as control yogurt. Therefore, UF powder could be substituted for skim milk powder without depressing yogurt qualify.

• Korean Journal of Soil Science and Fertilizer
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• v.34 no.3
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• pp.178-184
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• 2001

A study was carried out to investigate the effect of rice bran and charcoal meal application on growth in rice and bacterial population in paddy soil. Four different treatments were applied ; at whole layer placement of rice bran 1.8Mg/ha(1.8WR), surface of rice bran 1.8Mg/ha(1.8SR), charcoal meal 3.0Mg/ha(3.00M), and combined rice bran 1.8Mg/ha and charcoal meal 3.0Mg/ha (1.8R+3.0C) through field experiment. $NH_4-N$ and $NO_3-N$ in soil were high in the application of 1.8SR and 1.8R+3.0C until heading stage after rice bran application. Amount of nitrogen absorbed by rice plant were the highest in application of 1.8R+3.0C, and the lowest in application of 3.0CM. Rice yield was no differences among treatments. A number of total aerobic bacteria were the highest in application of 1.8R+3.0C at panicle formation stage of rice. Cellulose decomposers were high in application of 1.8SR at tillering stage and in application of 1.8R+3.0C at harvesting stage. The microorganisms of ammonia-oxidizing and denitrifying bacteria showed higher number in the application of 1.8R+3.0C and 1.8SR at tillering stage than heading stage. Azotobacter had tendency to decreased with the passage of time, but increased when rice bran was added. Athiorhodacea were numerous in the application of 1.8WR, but a few in the application of 3.0CM through growing period of rice plant.