• Journal of the Korean Society of Food Culture
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• v.20 no.4
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• pp.426-432
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• 2005

To develop a low-temperature and long-term fermented Baechu kimchi, kimchi was prepared according to a recipe of specific ratio with major and minor ingredients and adjusted its final salinity to 3.7%. Baechu kimchi fermented at $15{\pm}1^{\circ}C$ 24 hours and transferred them into in a refrigerator only for kimchi, and then continued to ferment at $-1{\pm}1^{\circ}C$ for 30 weeks to make a low-temperature and long-term fermented kimchi. The initial cutting force of 8.45kgf dropped gradually and reached to 5.19kgf after 30 weeks of fermentation. In compression force the gumminess, hardness and chewiness of Baechu kimchi showed a great decrease during the fermentation, but the springiness and adhesiveness increased in slight. Correlation coefficient between the chewiness and gumminess was the highest(r=0.879). In spite of sensory evaluation scores of the appearance and texture were the highest on 0 day of fermentation, the saltiness was evaluated the worst to eat. Scores for sourness and carbonated flavor were the best during 18 to 22 weeks of fermentation, and overall acceptability was the best after 14 weeks of fermentation. Very high correlation coefficients were revealed between the sourness and carbonated flavor(r=0.813) and between the sourness and off-flavor(r=0.805). According to these results we concluded that the best low-temperature and long-term fermented Baechu kimchi prepared with 3.7% salinity and fermented at $15{\pm}1^{\circ}C$ for 24 hours and then transferred into a kimchi refrigerator at $-1{\pm}1^{\circ}C$, and completed the fermentation for 18 weeks.

• Journal of Microbiology and Biotechnology
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• v.21 no.6
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• pp.627-636
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• 2011

A commercially important alkaline protease, produced by Bacillus sp. RRM1 isolated from the red seaweed Kappaphycus alvarezii (Doty) Doty ex Silva, was first recognized and characterized in the present study. Identification of the isolated bacterium was done using both biochemical characterization as well as 16S rRNA gene sequencing. The bacterial strain, Bacillus sp. RRM1, produced a high level of protease using easily available, inexpensive agricultural residues solid-state fermentation (SSF). Among them, wheat bran was found to be the best substrate. Influences of process parameters such as moistening agents, moisture level, temperature, inoculum concentration, and co-carbon and co-nitrogen sources on the fermentation were also evaluated. Under optimized conditions, maximum protease production (i.e., 2081 U/g) was obtained from wheat bran, which is about 2-fold greater than the initial conditions. The protease enzyme was stable over a temperature range of 30-$60^{\circ}C$ and pH 6-12, with maximum activity at $50^{\circ}C$ and pH 9.0. Whereas the metal ions $Na^+$, $Ca^{2+}$, and $K^+$ enhanced the activity of the enzyme, others such as $Hg^{2+}$, $Cu^{2+}$, $Fe^{2+}$, $Co^{2+}$, and $Zn^{2+}$ had rendered negative effects. The activity of the enzyme was inhibited by EDTA and enhanced by $Cu^{2+}$ ions, thus indicating the nature of the enzyme as a metalloprotease. The enzyme showed extreme stability and activity even in the presence of detergents, surfactants, and organic solvents. Moreover, the present findings opened new vistas in the utilization of wheat bran, a cheap, abundantly available, and effective waste as a substrate for SSF.

• Journal of Microbiology and Biotechnology
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• v.2 no.1
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• pp.35-40
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• 1992

The influence of the nature of plasmids on fermentation parameters such as cell growth, cell viability, plasmid stability, and product formation has been investigated using E. coli M5248 and its recombinant derivatives M5248 [pBR322], M5248[pAS1], and M5248[pNKM21]. At a low temperature ($30^\circ{C}$), the cell growth, cell viability, and protein synthesis of the recombinants were nearly identical to those of the host cell. However, at high temperature ($42^\circ{C}$), in which transcription from the P_L$ promoter is derepressed, the recombinant cells showed decreased stability along with lower growth rates and cell viability. The ratio of total protein to cell mass was in the order of E. coli M5248>M5248[pBR322]>M5248[pAS1]>M5248[pNKM21]. It was found that transcription from the $P_L$ promoter adversely affect the plasmid maintenance and host cell metabolism even in the absence of the cloned-gene expression. Furthermore, profiles of ${\beta}$ activity were shown to vary with recombinant strains. E coli M5248[pBR322] showed highest ${\beta}-lactamase$ activity at $30^\circ{C}$, while at $42^\circ{C}\;{\beta}-lactamase$ activity was significantly reduced irrespective of the strains. The effect of the plasmid properties on plasmid-encoded gene expression has been further examined based on the relationship between $\{beta}-lactamase$ activity and plasmid-harboring cell numbers.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.26 no.2
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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.

• Journal of Korean Society on Water Environment
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• v.22 no.2
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• pp.258-263
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• 2006

ANAMMOX (Anaerobic ammonium oxidation) reactor, which was cultivated ANAMMOX bacteria in mesophilic condition ($35^{\circ}C$), was operated to investigate the effects of temperature. In $20{\sim}30^{\circ}C$ of operation condition, which was assumed as field-temperature, total N removal and $NH_4-N$ removal rate were declined from about 2.50 and $1.27kg\;N/{m^3}_{reactor}-day$ (0.06 and 0.03 kg N/kgVSS/day) to 1.62 and $0.41kg\;N/{m^3}_{reactor}-day$ (0.04 and 0.01 kg N/kgVSS/day), In this range of temperature, ANAMMOX had very low activities but acid fermentation bacteria and denitrifiers, which were competitors of substrates, had high activities relatively. Though operation temperature was higher than inhibition condition for two months, ANAMMOX activities could not been recovered once they were inhibited by low temperature. This fact was resulted from very slow doubling time of ANAMMOX bacteria. This study shows that maintenance device of optimal temperature is necessary required in field application of ANAMMOX.

• Microbiology and Biotechnology Letters
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• v.23 no.1
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• pp.6-11
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• 1995

In order to screen microorganism producing lactic acid with high productivity from nature, we used a medium containing 100 g/l glucose and selected several microorganisms producing more than 80 g/l L-lactic acid. We investigated their physiological characteristics and compared them. The best microorganism was identified as Lactobacillus casei subsp. rhamnosus. The optimum pH for growth and production of lactic acid was 6.0 and this strain showed the highest growth rate at around 30$\circ$C , but the optimum temperature for lactic acid production was 45$\circ$C . The growth was inhibited proportionally from 50 g/l to 300 g/l of glucose and the maximal cell mass increased according to increasing the concentration of corn steep liquor (CSL) protein up to 30 g/l. In batch fermentation for lactic acid production, we produced 128 g/l L-lactic acid with 20 g/l CSL protein and 150 g/l glucose in 35 hours. In pH-stat fed-batch fermentation, we were able to produce 183 g/l L-lactic acid.

• Korean Journal of Food Science and Technology
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• v.14 no.3
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• pp.244-249
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• 1982

In order to reduce malic acid in low-alcohol content appel wine $(6{\sim}9%)$ malate-decomposing yeast, Schzosaccharomyces japonicus var. japonicus St-3 was used. Fallen apples before the harvesting season were collected and extraction was made. The apple extract was fortified with sucrose to make final sugar concentration of 18% in case of 9% base wine. High acid content in the primarily fermented apple wine could be reduced by following with malo-alcoholic fermentation using Schizosaccharomyces japonicus var. japonicus St-3 in second half of alcoholic fermentation using Saccharomyces sp. R-11. Secondary fermentation was proceeded at low temperature $(7{\sim}8^{\circ}C)$ for 130 days using Saccharomyces sp. R-11. Prior to the secondary fermentation, two percent of sugar was added to the base wine in order to produce carbon dioxide gas. And each five percent of specially prepared malt extract and hop extract were added to the base wine in order to increase foam stability. Better shelf-life was observed by keeping high carbon dioxide pressure$(2.3{\sim}2.5kg/cm^2)$ in the bottle. It was assured that the better low-alcohol content apple wine could be brewed by the method which we used above.

• Journal of the Korean Society of Food Science and Nutrition
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• v.34 no.5
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• pp.707-714
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• 2005

Ingredient ratio for making nabak kimchi and the manufacturing method were standardized from the available literatures. Fermentation properties and $CO_2$ production of the nabak kimchi were investigated during the fermentation at $5^{\circ}C,\;10^{\circ}C,\;and\;20^{\circ}C$. Standardized ingredients ratio of nabak kimchi that added 100 mL of water was as follows: 45.0 g baechu cabbage, 26.9 g radish, 1.9 g green onion, 1.0 g red pepper, 1.2 g crushed garlic, 0.9 g crushed ginger, 0.7 g red pepper powder. The standardized manufacturing method of nabak kimchi was as follows: washing ingredients, cutting radish and baechu cabbage $(2.5\times2.5\times0.5\;cm)$, salting for 20 min, washing and draining, pretreatment of ingredients, dissolving red pepper powder in water, blending, mixing, and adding the water to the mixed ingredients. Fermentations at $5^{\circ}C$ for 8 days, at $10^{\circ}C$ for 3 days, and at $20^{\circ}C$ for 1 day led to the acidity levels of $0.21\%,\;0.20\%,\;and\;0.31\%$, respectively. From the relationships between optimally ripened pH and acidity, nabak kimchi showed lower acidity of $0.20\~0.25\%$ with pH $4.2\~4.5.$ Like other kinds of kimchi, the Levels of Leuconostoc sp. were high specially at later stage of fermentation at low temperature $(5^{\circ}C)$. However, the levels of Lactobacillus sp. were low at $5^{\circ}C$. Nabak kimchi produced high levels of $CO_2$ in the initial fermentation period and followed by rapid decrease of $CO_2$ production with the fermentation. From the relationships between pH and $CO_2$ content, the highest $CO_2$ contents were found pH $4.0\~4.4$, 3.8 and 3.4 at $5^{\circ}C,\;10^{\circ}C$, and $20^{\circ}C$, respectively. This fact indicated that fermentation at $5^{\circ}C$ has the highest $CO_2$ content at optimally ripened pH of 4.3 and the fermentation at lower temperature such as $5^{\circ}C$ could extend the eatable time of nabak kimchi.

• Journal of the East Asian Society of Dietary Life
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• v.21 no.6
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• pp.853-862
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• 2011

We reproduced and investigated the quality characteristics of Samhaeju (one type of Korean traditional rice wine), which has been described in ancient documents. During fermentation, the room temperature was $9.1{\sim}25.0{\circ}C$, and each treatment's material temperature was $11.7{\sim}23^{\circ}C$. As the fermentation proceeded, the pH rapidly decreased (initial pH was 6.6~6.9) and rose gradually from the 18th day. Titratable acidity and amino acidity slowly increased in general. Regarding soluble solid contents, there were various change patterns depending on the production method, and they were affected by initial room temperature. In the treatments using 1 (Sang-ga-yo-rok), 3 (Eum-sik-di-mi-bang), 7 (Jo-sun-mu-ssang-sin-sik-yo-ri-je-beop), 8 (Sang-ga-yo-rok $15^{\circ}C$), reducing sugar contents decreased rapidly after 1st mashing day and then increased slightly after 2nd mashing. The alcohol content increased as the fermentation proceeded, and most of the treatments produced 1/2 the amount of total alcohol content before the 2nd mashing day, followed by a slight increase until the end of fermentation (about 100 days from the 2nd mashing day). In the sensory evaluation, Samhaeju using methods 2, 4, 5, and 6 got high scores and had much reducing sugar contents than other treatments. Among the seven manufacturing processes, method 2 was relatively simple and got the highest score in the sensory evaluation. Therefore, method 2 would be suitable for industrialization and popularization of Korean traditional alcoholic beverage.

• Journal of Microbiology and Biotechnology
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• v.28 no.3
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• pp.473-481
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• 2018

Owing to its high protein secretion capacity, simple nutritional requirements, and GRAS (generally regarded as safe) status, Bacillus licheniformis is widely used as a host for the industrial production of enzymes, antibiotics, and peptides. However, as compared with its close relative Bacillus subtilis, little is known about the physiology and stress responses of B. licheniformis. To explore its temperature-stress metabolome, B. licheniformis strains ATCC 14580 and B186, with respective optimal growth temperatures of $42^{\circ}C$ and $50^{\circ}C$, were cultured at $42^{\circ}C$, $50^{\circ}C$, and $60^{\circ}C$ and their corresponding metabolic profiles were determined by gas chromatography/mass spectrometry and multivariate statistical analyses. It was found that with increased growth temperatures, the two B. licheniformis strains displayed elevated cellular levels of proline, glutamate, lysine, pentadecanoic acid, hexadecanoic acid, heptadecanoic acid, and octadecanoic acid, and decreased levels of glutamine and octadecenoic acid. Regulation of amino acid and fatty acid metabolism is likely to be associated with the evolution of protective biochemical mechanisms of B. licheniformis. Our results will help to optimize the industrial use of B. licheniformis and other important Bacillus species.