• 한국미생물·생명공학회지
• /
• 제38권2호
• /
• pp.117-123
• /
• 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.

• Biotechnology and Bioprocess Engineering:BBE
• /
• 제5권2호
• /
• pp.141-145
• /
• 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.

• 한국지하수토양환경학회:학술대회논문집
• /
• 한국지하수토양환경학회 2001년도 추계학술발표회
• /
• pp.107-110
• /
• 2001

The biological control potential of entomopathogenic nematodes (EPN) can be enhanced by improved culture efficiency. Optimization of media is a key factor for improving in vitro mass production of entomopathogenic nematodes. EPN yield was dependant of complex medium concentration, of which mixture is carbohydrates, lipids, proteins, salts, and growth factors, on the growth of Heterorhabditis bacteriophora and its symbiotic bacterium Photorhabdus luminescensLipids.

• Biotechnology and Bioprocess Engineering:BBE
• /
• 제9권5호
• /
• pp.379-382
• /
• 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.

• 한국응용곤충학회지
• /
• 제41권3호
• /
• pp.225-231
• /
• 2002

곤충병원성 선충인 Steinernema carpocapsae All (ScA)과 포천(ScP) 계통, S.glaseri NC (SgN)와 동래(SgD) 계통, Heterorhabditis bacteriophora NC 1 계통(HbN)이 당근뿌리혹선충 (Meloidogyne hapla)의 난낭 형성에 미치는 영향을 구명하기 위하여 토마토를 이용한 pot실험을 수행한 결과는 다음과 같다. 450마리의 당근뿌리혹선충이 있는 100g 토양에 곤충병원성 선충을 2.5$\times$$10^{5}$ 마리 농도로 처리한 결과 ScA처리에서 9.4-36.5개, SgN처리에서 5.7-24.7개, HbN처리에서 11.2-16.0개로서 당근뿌리혹선충 단독 처리에서의 62.5개보다 난낭수가 매우 적었다. Steinernema선충을 100㎤당 100마리, 200마리의 당근뿌리혹선충에 대해 2,020마리/토양 350g와 1.6$\times$$10^{5}$ 마리 농도로 처리한 결과 Steinernema 선충의 종간, 계통별 또는 처리농도 간에는 난낭수의 차이가 없었으나, 당근뿌리혹선충 단독 처리와 비교하면 난낭수가 현저히 감소하였다 곤충병원성 선충을 당근뿌리혹선충 처리 3일 전에 처리한 것이 3일 후에 처리한 것보다 난낭 형성 억제에 더 효과적이었다. 한편, 곤충병원성 선충은 토마토의 생육에 아무런 영향을 끼치지 않았다.

• KSBB Journal
• /
• 제13권1호
• /
• pp.31-37
• /
• 1998

A simple method for the in vivo production of third-stage infective juveniles(IJs) of Steinernema glaseri was developed. Using Galleria mellonella larvae, only IJs can be rapidly generated inadequate quantities for field application. The nematode inoculation concentration and incubation temperature were critically important. The most effective temperature for infectivity of Steinernema glaseri IJs to Galleria mellonella larvae was 33$^\circ C$. However, the total number of menatodes harvested at 25$^\circ C$ about 66,000 IJs per larva was significantly greater than those at other temperatures. The optimal inoculation number of nematodes was 60 to 80 nematodes per host larva. The higher nematode inoculation concentration of 100 IJs per larva caused a rapid decrease in the total number of IJs harvested. As the inoculation medium pH increased, the number of IJs harvested increased and reached about 110,000 IJs per larva at pH 9.0. The pathogenicity of IJs decreased y increasing the salt concentration in the medium.

• 한국응용곤충학회지
• /
• 제35권1호
• /
• pp.80-84
• /
• 1996

곤충병원성선충과 곰팡이를 이용한 파리의 생물적 방제 가능성을 검토한결과, 여과지상에서의 큰집파리에 대한 고충병원성선충의 병원력은 동래에서 분리한 Steinernema glaseri strain이 $96.7\pm$2.8%의 치사유을 보여 가장 효과가 좋았으며, 다음이 S. carpocapsae로서 $90.0\pm$0.0%였고 함양에서 분리한 Heterorhabditis bacteriophora strain은 $86.7\pm$2.7%, 포천에서 분리한 S. carpocapsae strain은 $70.0\pm$9.4%였다. 농가 화장실에 곤충병원성선충 260,000마리씩을 처리한 경우, H. bacteriophora 함양 strain이 100%, S. glaseri 동래 strain이 $76.9\pm$3.9%, S. carpocapsae 포천 strain이 $58.5\pm$6.1%의 파리유충을 치사시켰다. 곤충병원성곰팡이 Beauveria brongniartii 7.0$\times${TEX}$10^{9}${/TEX} cfu를 단독처리한 농가 화장실에서는 집파리유충의 치사율이 $73.6\pm$0.1%였으나, S. carpocapsae포천 strain이 130,000마리와 곰팡이 혼합처리에서는 77.8$\pm$3.9%, H. bacteriophora 함양 strain 130,000마리와 곰팡이 혼합처리에서는 $77.7\pm$5.1%의 치사율을 보여, 파리방제의 곤충병원성선충과 곰팡이의 이용가능성이 있었다.

• 한국응용곤충학회지
• /
• 제39권3호
• /
• pp.149-152
• /
• 2000

곤충변원성충(Steinernema carpocapsae Weiser)의 감염태 유충에 대한 액체질소( $-190^{\circ}C$)냉동 저장하는 방법을 개발하기 위하여, 냉동보관 전처리 과정 및 저장기간에 따른 선충생존율과 감염력 변이를 조사하였다. 냉동저장 전에 22% 글리세롤로 선충은 6, 12, 24시간 동안 배양한 후 70% methanol($0^{\circ}C$)안에 10분간 유지하였다. 글리세롤과 methanol에 넣어 둔 샘플을 0,85% 식염수에 넣어 24시간 유지한 후 생존능력을 측정하였다. 글리세롤 배양시간에 따른 선충 생존율의 차이는 없었으나, methanol처리에서는 글리세롤 처리 시간이 길수록 선충 생존율이 높게 나타났다. 냉동저장에 따른 선충의 생존율은 글리세롤 배양시간이 짧았던 처리(6시간)를 제외하고는 5개월 동안 평균 70% 이상으로 높게 나타났다. 냉동저장 되었던 선충의 곤충감염율은 저장기간에 관계없이 90% 이상을 나타내었다. 이상의 결과는 곤충병원선충이 냉동저장에 의해 장기간보존이 가능하다는 것을 제시한다.

• 한국잠사곤충학회지
• /
• 제40권2호
• /
• pp.117-125
• /
• 1998

Entomopathogenic nematodes, Heterorhabditidae and Steinernematidae, were isolated from the soil of mulberry field, and the high infectivity and invesiveness were confirmed in the silkworm, Bombyx mori. The cause of non-microbial and acute flacherie was found as an disease by infection with soil-born nematodes through the mulberry leaves contaminated with soil and rainwater. The causal nematodes were isolated by silkworm trap from all of the 5 soil samples collected on the 5 mulberry fields, and identified as 3 strains of Heterorhabditis sp. and 2 of Steinernema sp. Rainwater itself, however, wasn't engaged in the silkworm disease, mulberry leaves with rainwater was rather profitable for cocoon production when the leaf quality was too hard to feed silkworm. Feeding of wet mulberry leaves with rain might not so harm to silkworm when the condition of rearing room to be kept at suitable temperature and ventilated well. Nematode infection of silkworm could be occurred by harvesting and feeding of contaminated mulberry leaves on the weather condition of rainy and wind. For the prevention of nematode infection, silkworms should be fed the leaves harvested from the higher portion of the mulberry tree in rainy days. For an oppositional application of this susceptibility of silkworms to nematode, might be useful on the collection and amplification of nematode agents for biotic control of pest insects.

• KSBB Journal
• /
• 제14권2호
• /
• pp.198-204
• /
• 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.