• Biotechnology and Bioprocess Engineering:BBE
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• v.5 no.2
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• pp.141-145
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• 2000

Entomopathogenic nematodes are being used for insect control. We purified a toxin secreted by the insect-pathogenic bacterium, Xenorhadbus nematophilus, which lives in the gut of entomopathogenic nematodes. Culture broth of X. nematophilus was separated by centrifugation and concentrated by ultration. The concentrated culture broth was applied to a DEAE Sephadex A-50 column, and proteins were eluted stepwise with increasing concentrations of KCI. Fractions column. The molecty weight of purified toxin was39 kDa on SDS-PAGE, and Fourier tranformed infrared (FTIR) spectroscopy indicated that this toxin could be a new protein exhiting the charactristics of C=O stretching peak near 1650cm-1.

• 한국생물공학회:학술대회논문집
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• 2001.11a
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• pp.910-913
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• 2001

The fatty acid compositions of entomopathogenic nematodes Steinernema carpocapsae strain produced in vitro and in vivo were examined. Nematodes cultured both in vitro and in vivo revealed similar fatty acids compositions with respect to 16, 18, 20 carbons. However, the contents of lipids were varied by culture methods. Furthermore, it was distinctive that nematodes cultured in vitro contained fatty acids with 19 carbon. In the case of symbiotic bacterium Xenorhabdus nematophilus isolated from Steinernema carpocapsae, the major lipid component was palmitic (c16:0) fatty acids.

• KSBB Journal
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• v.14 no.2
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• pp.198-204
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• 1999

Asymbiotic bacterium with highly effective toxins was isolated from entomopathogenic nematode Steinernema glaseri which has been widely used against various soil-inhabiting pests. The symbiont of S. glaseri was identified as Xenorhabdus nematophilus sp. by using several biochemical and physiological tests. When this strain was released into the hemolymph of insect larva, it produced highly toxic substances and killed the larva within 2 days. Two colony forms that differed n some biochemical characteristics were observed when cultures in vitro. Phase l colonies were mucid and difficult to be dispersed in liquid. Phase II was not mucoid and was easily dispersed in liquid. It did not adsorb neutral red or bromothymol blue. Rod-shaped cell size was highly variable between two phases, ranging 2-10 ${\mu}{\textrm}{m}$. It was also found that only infective-stage nematodes can carry only primary-phase Xenorhabdus in their intestine.

• Journal of Microbiology and Biotechnology
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• v.12 no.3
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• pp.526-529
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• 2002

Lysis of erythrocytes isolated from human, rabbit, and mouse blood samples was investigated with the culture supernatant of Xenorhabdus nematophilus in a primary form. Prior to use, the culture supernatant of the bacteria was concentrated and the concentrate was dialyzed against Tris-HCl buffer (10 mM, pH 8.1) by ultrafiltration using PM-5 membrane with a molecular weight cut-off of 5,000. At $30^{\circ}C$, the supernatant exhibited no lytic activity towards three types of erythrocytes. However, at $4^{\circ}C$, the supernatant showed selective lytic activity towards rabbit erythrocytes within 90 min. yet did not lyze human or mouse erythrocytes. Microscopic examination clearly revealed that most of the rabbit erythrocytes had been fumed into ghost forms.

• Biotechnology and Bioprocess Engineering:BBE
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• v.9 no.5
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• pp.379-382
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• 2004

Entomopathogenic nematodes are used for insect control. Herein, an extracellular protease was partially purified from a culture supernatant of Xenorhabdus nematophilus, a symbiotic bacterium of an entomopathogenic nematode, Steinernema glaseri: using precipitation with $80\%$ v/v isopropyl alcohol followed by gel permeation chromatography with a packed Sephacryl S-300 HR media. The partially purified protease exhibited maximal activity at pH 7 in the presence of 1 mM $CaCl_2$. The protease was identified as a metallo-protease based on the inhibition of its activity by the metal chelating agent, EDTA.

• Korean journal of applied entomology
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• v.54 no.2
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• pp.55-62
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• 2015

'Bt-Plus' has been developed by mixing spores of Bacillus thuringiensis (Bt) and culture broth of Xenorhabdus nematophila (Xn). Despite its high toxicity, it has some imitation to broaden its efficacy against diverse insect pest spectrum. This study focuses on enhancement of Bt-Plus toxicity against semi-susceptible insect, Spodoptera exitgua, by addition of Xn metabolites. Two main Xn metabolites, oxindole (OI) and benzylideneacetone (BZA), are known to enhance the Bt insecticidal activities. The addition of OI or BZA significantly increased Bt-Plus pathogenicity. However, when the freeze-dried Xn culture broth was added to Bt-Plus, much less amount was enough to enhance the toxicity compared to the amount of OI or BZA. An HPLC analysis indicated that there were more than 12 unidentifed bacterial metabolites in Xn culture broth. These suggest that there are potent biological response modifiers in Xn metabolites other than OI and BZA.

• KSBB Journal
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• v.17 no.3
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• pp.276-282
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• 2002

Symbiotic bacteria with highly effective insecticidal activities were isolated and compared with their physiological characteristics from seven species of entomopathogenic nematodes belong to Steinernamatidae and Heterorhabditidae sp., and three of them were identified as Xenorhabdus nematophilus. Culture characteristics, insecticidal activities, pretense activities and fatty acid contents of various symbiotic bactierial isolates were also examined. In the case of cell growth and insecticidal activity, XR-PC and XR-MK were superior to other species when cultured in vitro. The insecticidal activity were highest at the early exponential growth phase, and gradually decreased with time. The protease activity of XR-DR was remarkable compared to other species. In the case of HE-HY, however the pretense activity increased in parallel with cell growth. Interestingly, the fatty acid patterns of Xenorhabdus nematophilus isolated from different emtomopathogenic nematode, showed remarkable differences in their contents of 12:0, 14:0, 16:1 cia 5 and 17:0 cyclo and hydroxy and branch factty acids were varied from 2% to 15% among total fatty acid contents.

• Research in Plant Disease
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• v.16 no.2
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• pp.170-175
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• 2010

A monoterpenoid benzylideneacetone (BZA) is a bacterial metabolite isolated from culture broth of an entomopathogenic bacterium, Xenorhabdus nematophila K1. It was tested in this study the control efficacy of the metabolite against two major fungal diseases occurring in red-pepper plants. BZA exhibited significant antifungal activities against Phytophthora capsici and Colletotrichum acutatum. Under natural light conditions, the antifungal activity of BZA was maintained for more than sixty days. The antifungal activity of BZA was not lost even in soil because the incidence of Phytophthora blight against red-pepper plants was significantly reduced when the suspensions of P. capsici were poured to the rhizosphere soils mixed with BZA. Application of the BZA suspension spray to the fruit surface infected with C. acutatum significantly suppressed the disease occurrence of anthracnose on the red-pepper plants. These results suggest that BZA can be used to develop a promising agrochemical to control phytophthora blight and anthracnose of redpepper plants.

• The Korean Journal of Pesticide Science
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• v.18 no.3
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• pp.181-190
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• 2014

An entomopathogenic bacterium, Bacillus thuringiensis (Bt), can sporulate along with production of insecticidal Cry toxins. Bt Cry toxins exhibit relatively narrow spectrum to target insects due to their specific interactions with midgut receptors. This study designed several strategies to enhance Bt efficacy in target insect spectrum and insecticidal activity. Four Cry toxins were purified from four different Bt strains and showed relatively narrow target insect spectrum. However, the Cry mixtures significantly expanded their target insect spectra. The additional effect of baculovirus to Cry toxin was tested with recombinant baculoviruses expressing Cry1Ac or Cry1Ca. However, the baculovirus was little effective to expand target insect spectrum. Bacterial culture broth of Xenorhabdus nematophila (Xn) significantly suppressed insect cellular immune response and increased Cry toxicity. The addition of Xn culture broth to Cry mixture significantly enhanced Bt efficacy in target insect spectrum and insecticidal activity.

• Korean journal of applied entomology
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• v.42 no.4
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• pp.353-360
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• 2003

Immunodepression can be required for entomopathogenic bacteria to induce their potent pathogenicities to the target insects. Here, we raise a hypothesis that the capacity of a pathogenic bacterium to induce the target insect immunodepression has positive relationship with the degree of pathogenicity. X. nematophilus had 1,200 times as potent as another entomopathogenic bacterium, Staphylococcus gallinarum against the fifth instar larvae of silkworm, Bombyx mori, when they were Injected into the hemocoel. Although both bacteria had significant cytotokic effect on the hemocytes of B. mori, X. nematophilus gave faster and greater cytotoxicity than did S. gallinarum. In cellular immune reactions, B. mori could form 20 hemocyte nodules against the bacterial injection with 5${\times}$10$\^$5/ cells. The number of the hemocyte nodules was significantly depressed when live X. nematophilus was inject-ed, but not in S. gallinarum. Activation of prophenoloxidase (proPO) was depressed in the bacterial injection. The depression of PO activation was significantly greater in X. nematophilus infection than in S. gallinarum injection. Lysozyme activity was induced by the injection of S. gallinarum at 4 h after the treatment, but not induced in X. nematophilus at all the time. These results showed that X. nemato-philus induced greater immunodepression against B. mori and resulted in higher pathogenicity than did S. gallinarum. Therefore, this study suggests that the immunodepression induced by entomopathogenic bacteria has positive relationship with their pathogenicity.