• Korean Journal of Microbiology
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• v.17 no.4
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• pp.198-202
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• 1979

Three Pseudomonas spp. and one Zoogloea sp. which could docompose the furfural were isolated from the enriched undefined cultures of soil. In the decompositioin of furfural thyey demonstrated protocooperation and synergism, utilizing 2-furoic acid a certain sudstance fural was subject to complete oxidation, which resulted in decolorization by mutural interactions. The decomposition was more efficient in mixed cultures than in a single culture.

• Proceedings of the Korean Society for Applied Microbiology Conference
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• 2000.04a
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• pp.201-207
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• 2000

The strategies of commercial development have been focused on the economy of scale for a process. The design of media has been recognized as a key in assuring mass production of entomopathogenic nematodes. Media optimization was conducted with insect host, proteins, lipids, and symbiotic bacteria mass. G. mellonella (insect host) produced about 290,000 infective juveniles per one. Complex media produced about 250,000 infective juveniles / ml in liquid culture within 8 days (one generation).

• 한국생물공학회:학술대회논문집
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• 2002.04a
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• pp.473-476
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• 2002

A lignin degradation bacteria, symbiotic bacteria was isolated from the gut of Sympetrum depressiusculum and tested for its lignin degrading activity using lignin model compounds and related aromatic compounds. The strain was identified as Serratia marcescens HY-5 based on the 165 rDNA, cellular fatty acid composition, biochemical and physiological characteristics. S. marcescens showed 40-50% lignin degrading activity in the media that contained vaillin, guaiacol and dealkaline lignin. S. marcescens showed three ligninase activities [Jaccase, lignin peroxidase(LiP) and Manganase peroxidase(MnP)]. Addition of dealkaline lignin to the basal media increased about 6fold of laccase activity. Vanillic acid or vanillin increase 1.3fold of MnP activity and p-coumaric acid increased 12fold of LiP activity which added to the basal medium.

• Journal of Microbiology and Biotechnology
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• v.30 no.9
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• pp.1367-1378
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• 2020

The polyphagous eri silk moth, Samia ricini, is associated with various symbiotic gut bacteria believed to provide several benefits to the host. The larvae of S. ricini were subjected to isolation of gut bacteria using culture-dependent 16S rRNA generic characterization, metagenomics analysis and qualitative enzymatic assays. Sixty culturable aerobic gut bacterial isolates comprising Firmicutes (54%) and Proteobacteria (46%); and twelve culturable facultative anaerobic bacteria comprising Proteobacteria (92%) and Firmicutes (8%) were identified inhabiting the gut of S. ricini. The results of metagenomics analysis revealed the presence of a diverse community of both culturable and un-culturable gut bacteria belonging to Proteobacteria (60%) and Firmicutes (20%) associated with seven orders. An analysis of the results of culturable isolation indicates that these bacterial isolates inhabited all the three compartments of the gut. Investigation on persistence of bacteria coupled with metagenomics analysis of the fifth instar suggested that bacteria persist in the gut across the different instar stages. In addition, enzymatic assays indicated that 48 and 75% of culturable aerobic, and 75% of anaerobic gut bacterial isolates had cellulolytic, lipolytic and nitrate reductase activities, thus suggesting that they may be involved in food digestion and nutritional provision to the host. These bacterial isolates may be good sources for profiling novel genes and biomolecules for biotechnological application.

• Microbiology and Biotechnology Letters
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• v.25 no.1
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• pp.89-95
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• 1997

The current processer of the textile wastewater treatment are mostly consisted of a combination of a physico-chemical and a biological treatment. The overall efficiency of these processes is, however, assessed to be fairly low. It is even worse during the summer season when temperature of the wastewater rises above 40$\circ $C. Therefore, a feasible process of the textile wastewater treatment which can work efficiently at higher temperatures was investigated in this work. We used a bench scale reactor consisted of one 4 liter anaerobic and one 8 liter aerobic tank, and the thermophilic symbiotic PVA degraders, Pasteruella hemolytica KMG1 and Pseudomonas sp. KMG6 that had been isolated in our laboratory. In the preliminary flask experiments, we observed that the thermophilic symbiotic PVA degraders could not grow in the wastewater substrate. Then, we isolated the mutant strains by acclimating the KMG1and KMG6 strains to the wastewater medium. The mutant symbionts (KMG1-1 and KMG6-1) were isolated through 6 times successive transfers into the fresh wastewater medium after 5 days culture for each. The mutant strains obtained grew well in the mixed medium composed of 75% wastewater and 25% synthetic medium, and supplemented with 0.5% PVA as a sole carbon source. During the culture for 14 days at pH 7.0 and 40$\CIRC $C, the bacteria assimilated about 89% of the added PVA. The symbionts degraded equally well all the PVA substrates of different molecular weight (nd=500~30000). In contrast to the flask experiments, in the reactor system the mutant strains showed very low levels of the PVA and COD removal rates. However, the new reactor system with an additional aerobic tank attained 82% removal rate of COD, 94% of PVA degradation and 71% of color index under the conditions of 5% inoculm on the tank 2, incubation temperature of 40$\circ $C, dissolved oxygen level of 2~3 mg/l and retention time of 30 hours. This result ensures that the process described above could be an efficient and feasible treatment for the PVA contained textile wastewater at higher temperatures.

• Journal of Microbiology and Biotechnology
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• v.17 no.3
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• pp.420-427
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• 2007

We investigated the temperature effects on the virulence, development, reproduction, and otility of two Korean isolates of entomopathogenic nematodes, Steinernema glaseri Dongrae strain and S. longicaudum Nonsan strain. In addition, we studied the growth and virulence of their respective symbiotic bacterium, Xenorhabdus poinarii for S. glaseri and Xenorhabdus sp. for S. longicaudum, in an insect host at different temperatures. Insects infected with the nematode-bacterium complex or the symbiotic bacterium was placed at $13^{\circ}C,\;18^{\circ}C,\;24^{\circ}C,\;30^{\circ}C,\;or\;35^{\circ}C$ in the dark and the various parameters were monitored. Both nematode species caused mortality at all temperatures tested, with higher mortalities occurring at temperatures between $24^{\circ}C\;and\;30^{\circ}C$. However, S. longicaudum was better adapted to cold temperatures and caused higher mortality at $18^{\circ}C$ than S. glaseri. Both nematode species developed to adult at all temperatures, but no progeny production occurred at $13^{\circ}C\;or\;35^{\circ}C$. For S. glaseri, nematode progeny production was best at inocula levels above 20 infective juveniles/host at $24^{\circ}C\;and\;30^{\circ}C$, but for S. longicaudum, progeny production was generally better at $24^{\circ}C$. Steinernema glaseri showed the greatest motility at $30^{\circ}C$, whereas S. longicaudum showed good motility at $24^{\circ}C\;and\;30^{\circ}C$. Both bacterial species grew at all tested temperatures, but Xenorhabdus sp. was more virulent at low temperatures $(13^{\circ}C\;and\;18^{\circ}C)$ than X. poinarii.

• Journal of Microbiology and Biotechnology
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• v.21 no.8
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• pp.869-873
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• 2011

Most medium formulations for improving culture of entomopathogenic nematodes (EPN) based on protein sources have used enriched media like animal feed such as dried egg yolk, lactalbumin, and liver extract, among other ingredients. Most results, however, showed unstable yields and longer production time. Many of the results do not show the detailed parameters of fermentation. Soy flour, cotton seed flour, corn gluten meal, casein powder, soytone, peptone, casein hydrolysates, and lactalbumin hydrolysate as protein sources were tested to determine the source to support optimal symbiotic bacteria and nematode growth. The protein hydrolysates selected did not improve bacterial cell mass compared with the yeast extract control, but soy flour was the best, showing 75.1% recovery and producing more bacterial cell number ($1.4{\times}10^9$/ml) than all other sources. The highest yield ($1.85{\times}10^5$ IJs/ml), yield coefficient ($1.67{\times}10^6$ IJs/g medium), and productivity ($1.32{\times}10^7$ IJs/l/day) were also achieved at enriched medium with soybean protein.

• The Korean Journal of Zoology
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• v.26 no.3
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• pp.181-192
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• 1983

Cytosol protein patterns of two strains of A. proteus, tD and xD strain, were compared by two dimensional gel electrophoresis. Among the 200 major polypeptides that could be stained by silver stain method, tD strain contained a cell specific protein whose molecular weight was 45,000 dalton, pI 5.9. On the other hand, the cytosol and the symbiotic vesicles of xD strain contained a symbiosis specific protein (M.W. 29,000; pI 5.5). The fate of the symbiosis specific protein depended on the presence of symbiotic bacteria in the experiment of high temperature effect and of experimental infection. The significance of these results is discussed in relation to their function in organismic association on the basis of the previous findings.

• Microbiology and Biotechnology Letters
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• v.38 no.2
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• pp.117-123
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• 2010

BT toxin is produced by a soil bacterium Bacillus thuringiensis and has long been used as a biological insecticide without any competition. Recently, Photorhabdus, a symbiotic bacterium from entomopathogenic nematodes, family Heterorhabditae, has been researched and discussed as alternatives to B. thuringiensis. Photorhabdus, which lives in the gut of entomopathogenic nematodes, is a highly virulent pathogen of a wide range of insect larvae. When an insect is infected by the nematodes, the bacteria are released into the cadaver, and produce a number of insecticidal toxins. The biological role of the different Photorhabdus toxins in the infection process is still unclear. Photorhabdus toxin complex (Tc) is highly secreted gut-active toxin and has been characterized as a potent three-component (A, B and C) insecticidal protein complex. These components are necessary for full oral activity against insect larvae. The Photorhabdus PirAB binary toxins exhibit a potent injectable activity for Galleria mellonella larvae, and have oral toxicity against mosquitoes and caterpillar pest Plutella xylostella. Other toxin, 'makes caterpillars floppy' (Mcf) showed injectable activity on caterpillars. Recombinant Mcf triggers apoptosis in both insect hemocytes and the midgut epithelium and carries a BH3 domain. In this review, the relationship between the Photorhabdus and the nematode is discussed and recent important insecticidal toxins from Photorhabdus are described.

• Journal of Life Science
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• v.25 no.5
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• pp.568-576
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• 2015

The marine microalga Pavlova viridis can grow fast and has the ability to accumulate essential nutrients for culturing marine animals, such as EPA and DHA, and it has been used as food for raring larval fish and prawn. The symbiotic relationship between the flagellate microalga Pavlova viridis and its associated bacteria was investigated. An axenic culture of P. viridis was obtained by repeated treatment of the microalga with an antibiotic cocktail. The axenic status was confirmed after sub-culturing three times in a sterile f/2 medium without an antibiotic. The axenic alga was then co-inoculated with five bacteria, arbitrarily designated as I1–I5, isolated from the alga to test the growth promotion of the algae. All bacterial strains promoted the growth of P. viridis, and bacterial isolate I3 was the most effective among the five bacteria tested. The cell number of P. viridis in the co-culture with I3 was significantly higher than that of the control culture. A sequence analysis of the 16S rRNA gene isolated from I3 revealed a 97% nucleotide sequence similarity to that of Citrobacter sp. The growth of strain I3 was also significantly enhanced by co-culturing with P. viridis, indicating a symbiotic relationship between the microalga and its associated bacterium. The association between the microalga and bacterium was confirmed by scanning electron microscopy.