• Journal of Microbiology and Biotechnology
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• v.22 no.9
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• pp.1279-1287
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• 2012

We established an efficient transformation method for thermophile Geobacillus kaustophilus HTA426 using conjugative transfer from Escherichia coli of host-mimicking plasmids that imitate DNA methylation of strain HTA426 to circumvent its DNA restriction barriers. Two conjugative plasmids, pSTE33T and pUCG18T, capable of shuttling between E. coli and Geobacillus spp., were constructed. The plasmids were first introduced into E. coli BR408, which expressed one inherent DNA methylase gene (dam) and two heterologous methylase genes from strain HTA426 (GK1380-GK1381 and GK0343-GK0344). The plasmids were then directly transferred from E. coli cells to strain HTA426 by conjugative transfer using pUB307 or pRK2013 as a helper plasmid. pUCG18T was introduced very efficiently (transfer efficiency, $10^{-5}-10^{-3}\;recipient^{-1}$). pSTE33T showed lower efficiency ($10^{-7}-10^{-6}\;recipient^{-1}$) but had a high copy number and high segregational stability. Methylase genes in the donor substantially affected the transfer efficiency, demonstrating that the host-mimicking strategy contributes to efficient transformation. The transformation method, along with the two distinguishing plasmids, increases the potential of G. kaustophilus HTA426 as a thermophilic host to be used in various applications and as a model for biological studies of this genus. Our results also demonstrate that conjugative transfer is a promising approach for introducing exogenous DNA into thermophiles.

• Mycobiology
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• v.42 no.2
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• pp.181-184
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• 2014

To the best of our knowledge, this is the first report on thermophilic fungi isolated in Korea. Three species of thermophiles were isolated from compost and were identified as Myriococcum thermophilum, Thermoascus aurantiacus, and Thermomyces lanuginosus. They can grow at temperatures above $50^{\circ}C$ and produce high levels of cellulolytic and xylanolytic enzymes at high temperatures. Notably, the considerable thermostability of the endo-glucanase produced by T. aurantiacus has made the fungus an attractive source of industrial enzymes.

• Journal of Microbiology and Biotechnology
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• v.24 no.4
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• pp.475-482
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• 2014

The metabolic pathway of eugenol degradation by thermophilic Geobacillus sp. AY 946034 strain was analyzed based on the lack of data about eugenol degradation by thermophiles. TLC, GC-MS, and biotransformation with resting cells showed that eugenol was oxidized through coniferyl alcohol, and ferulic and vanillic acids to protocatechuic acid before the aromatic ring was cleaved. The cell-free extract of Geobacillus sp. AY 946034 strain grown on eugenol showed a high activity of eugenol hydroxylase, feruloyl-CoA synthetase, vanillate-O-demethylase, and protocatechuate 3,4-dioxygenase. The key enzyme, protocatechuate 3,4-dioxygenase, which plays a crucial role in the degradation of various aromatic compounds, was purified 135-fold to homogeneity with a 34% overall recovery from Geobacillus sp. AY 946034. The relative molecular mass of the native enzyme was about $450{\pm}10$ kDa and was composed of the non-identical subunits. The pH and temperature optima for enzyme activity were 8 and $60^{\circ}C$, respectively. The half-life of protocatechuate 3,4-dioxygenase at the optimum temperature was 50 min.

• Food Science of Animal Resources
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• v.39 no.5
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• pp.704-724
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• 2019

This study mainly investigated the improvement effect of nitroso-hemoglobin (NO-Hb) and four lactic acid bacteria (LAB) (Streptococcus thermophiles, Lactobacillus bulgaricus, Lactobacillus casei, and Montessori enterococcus) on the color and microbiological qualities of raw beef. Three strains of Escherichia coli, Staphylococcus, Salmonella, and Pseudomonas were used as pathogenic bacteria. The results showed that both NO-Hb and LAB could enhance the color stability and scavenged the spoilage bacteria in a minced beef model. But the improvement effect of NO-Hb was more significant than LAB. This suggested that NO-Hb, as a novel ingredient, could be used as a promising substitute for nitrite in meat products to improve the color and safety of meat products. In addition, low field (LF)-NMR method has been established to be practicable to identify changes in the relaxation times of water and fat caused by different type of bacteria and the storage periods. The number of relaxation components in minced beef was affected by bacteria and increase of the storage period.

• Journal of Korea Society of Waste Management
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• v.34 no.2
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• pp.140-147
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• 2017

This study was conducted to evaluate the effects of physical characteristics. Twelve specific odorous compounds and various sources of bacteria were tested via treatment of food waste using an ultra-thermophilic aerobic composting process. Food waste was mixed with seed material and operated for 47 days. During composting, the temperature was maintained at $80-90^{\circ}C$. The variations in $O_2$, $CO_2$ and $NH_3$ production suggested typical microorganism-driven organic decomposition patterns. After composting, the concentrations of 12 specific odorous compounds other than ammonia did not exceed the allowable exhaust limits for odor. After composting, thermophiles represented 50% of all bacteria. After composting, the percentage of thermophile bacterial increased by 15%. Therefore, both stable composting operation and economic benefit can be expected when an ultra-thermophilic composting process is applied to food waste.

• Microbiology and Biotechnology Letters
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• v.32 no.1
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• pp.29-36
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• 2004

$\alpha$-Cyclodextrin glucanotransferase excreted from a newly isolated Geobacillus thermosacchalytycus was purified through the ultrafiltraion, hydrophobic Sepharose CD-4B affinity chromatography, and gel filtration on Sephadex G-75, respectively. The molecular weight of the purified CGTase was 69 kDa and its N-terminal amino acid sequence was determined to be Asn-Leu-Asn-Lys-Val-Asn-Phe-Val-Ser-Asp-Val-Val-Val-Gln-Ile. The optimum pH and temperature were pH 6.0 and$ 60^{\circ}C$, respectively, and stably at the pH range of 6.0-8.0 and $60^{\circ}C$ in the presence of $Ca^{++}$. The excreted CGTase from the thermophilic G. thermosacchalytycus was $\alpha$-type showing a high coupling activity for the transglycosylation on various glucosides. The coupling reaction was carried out according to the random ternary complex mechanism.m.

• Magazine of the Korean Society of Agricultural Engineers
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• v.28 no.3
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• pp.99-106
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• 1986

This study was carried out to investigate the effects of moisture content, temperature, C/N ratio and pH of the sewage sludge mixed with hulle and sawdusts for making compost under aerobic condition and to improve the defect of the structure of experimental equipment heat lose and handling method. and obtained results were as follows 1.The temperature was reached 73$^{\circ}$ C around 50 hours fermentation in the condition of 0.8 L/min. of air and 60.4% of moisture content. and favorable moisture content of initial condition ranged from 50 to 65% 2.The temperature near bottom of the batch composter was decreased due to evaporate water vapor and lose the heat produced during aeration. and it is required to be improved. 3.The temperature in the batch composter from the center to the inside wall surface was gradually decreased. the temperatures of the points located in r=9cm and the wall surface were 4$^{\circ}$ C and 6$^{\circ}$ C respectively. and therefore it is required to be insulated. 4. The maximum C02 production was obtained as 7.3% per volume in the temperature of 63$^{\circ}$C at the moisture content of 60% 5.The temperature range of active microbes growth was found to be as 20$^{\circ}$C to 40$^{\circ}$C in the case of mesophiles and 50$^{\circ}$C to 65$^{\circ}$C in the case of thermophiles due to increase and decrease C02 production. 6.C/N ratio after decomposition was 1.3 to 2.6 smaller than that of initial one due to increase the amount of nitrogen. The more C/N ratio increased. the less the reaction velocity decresed. The optimum of it as found to be 30. 7.pH values after decomposition were slightly increased than that of initial ones. The reaction velocity was decreased at acid and alkall condition. Therefore it is neseseary to neutralize the medium to improve the reaction.

• Korean Journal of Food Science and Technology
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• v.26 no.2
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• pp.167-171
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• 1994

With a view to improving microbiological quality of spinach powder which is currently used for convenience food production, comparative efficacy of ethylene oxide(EO) fumigation and gamma irradiation was investigated by determining microbial populations and physicochemical quality for treated samples. Spinach powder was contaminated with various microorganisms ranging from $10^{2}/g\;to\;10^{4}/g$, which composed of thermophiles, acid tolerant bacteria, fungi, coliforms, etc. Microorganisms contaminated were destroyed up to undetected levels by gamma irradiation at below 7 kGy. showing the radiosensitivity $D_{10}$ 2.93 kGy on total aerobic bacteria. Ethylene oxide fumigation, however. was found unsatisfactory for physicochemical quality as well as microbial decontamination of the sample. It has been generally observed that influence of optimum-dose range of irradiation on the physicochemical qualities was insignificant, which was proved in the organoleptic evaluations on the stored sample.

• Food Science of Animal Resources
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• v.35 no.5
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• pp.683-691
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• 2015

The objective of this study was to identify the coccoidal bacteria present in 188 samples of fermented yaks’, mares’ and cows’ milk products collected from 12 different regions in Mongolia. Furthermore, we evaluated the fermentation properties of ten selected isolates of the predominant species, Streptococcus (S.) thermophiles, during the process of milk fermentation and subsequent storage of the resulting yoghurt at 4℃. Overall, 159 isolates were obtained from 188 samples using M17 agar. These isolates were presumed to be lactic acid bacteria based on their gram-positive and catalase-negative properties, and were identified to species level using 16S rRNA gene sequence analysis. These coccoid isolates were distributed in four genera and six species: Enterococcus (E.) durans, Enterococcus (E.) faecalis, Lactococcus (Lac.) subsp. lactis, Leuconostoc (Leuc.) lactis, Leuconostoc (Leuc.) mesenteroides. subsp. mesenteroides and S. thermophilus. Among these S. thermophilus was the most common species in most samples. From evaluation of the fermentation characteristics (viable counts, pH, titratable acidity [TA]) of ten selected S. thermophilus isolates we could identify four isolates (IMAU 20246, IMAU20764, IMAU20729 and IMAU20738) that were fast acid producers. IMAU20246 produced the highest concentrations of lactic acid and formic acid. These isolates have potential as starter cultures for yoghurt production.

• Journal of Applied Biological Chemistry
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• v.59 no.4
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• pp.345-349
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• 2016

This study was performed to evaluate the quality characteristics of curd yogurt with different contents [0.5~2.0% (w/w)] of Korean rice wine lees powder (KRWLP). Yogurt was fermented with commercially available mixed lactic acid bacteria (Lactobacillus acidophilus, Bifidobacterium longum, Streptococcus thermophiles) at $40^{\circ}C$ for 15 h. Acid production (pH and titratable acidity) of yogurts increased with increasing KRWLP content. After 12 hours fermentation, titratable acidity of KRWLP yogurt was 1.19~1.29 % and was higher than that (1.07 %) of yogurt made without KRWLP. And also, the number of viable lactic acid bacterial cell increased and the culture time to obtain maximum number of lactic acid bacteria cell decreased with the addition of KRWLP. The curd stability in yogurt was significantly enhanced by repression of whey separation in KRWLP yogurt. In sensory evaluation, there was a similar preference for KRWLP yogurts and the control. These results suggest that KRWLP can be used as foodstuff to improve the quality characteristics of yogurt.