• 한국미생물·생명공학회지
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• 제38권2호
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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.

• 한국미생물·생명공학회지
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• 제29권2호
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• pp.104-109
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• 2001

공생 박테리아 Photorhabdus sp. strain TF 균체량이 증가함에 따라서 병원성 선충 Heterorhabditis bacteriophora의 Infective Juveniles의 생산이 증가되었다. 이 공생 박테리아의 성장 최적 조건은 각각 배양 온도 3$0^{\circ}C$ 그리고 초기 배지 pH 5.5부터 7.3 사이에서 얻어졌다. 통기 상태에서 박테리아 균체의 생산과 성장이 촉진됨이 밝혀졌다. Photorhabdus sp. strain TF 박테리아의 성장 중 생산된 색소와 배양액의 pH의 변화는 박테리아의 성장 정도 나타내어 액체배양에서 병원성 선충 Heterorhabditis bacteriophora의 접종시기로 표시로서 이용할 수 있을 것이다.

• 한국유기농업학회지
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• 제30권3호
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• pp.423-439
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• 2022

The acute dermal and eye irritation tests of Photorhabdus temperata, a symbiotic bacterium of Heterorhabditis megidis Gwangju strain, were carried out in New Zealand white rabbit (Oryctolagus cuniculus), following the guidelines of OECD and Rural Development Administration (RDA) of Korea. In both tests, neither dermal nor eye responses were found from all the P. temperata treated rabbits and the results were classified as non-irritating. That is, erythema, eschar, edema, and any other dermal critical signs were not observed from all the experimental rabbits in the dermal irritation test. In the acute eye irritation test, no clinical signs of cornea, iritis, conjunctiva (redness, edema, lacrima, and chemosis) were observed from all the experimental rabbits. Individual ocular irritation, mean ocular irritation, and acute ocular irritation were calculated as 0.0. The results of dermal and eye irritation studies on P. temperata indicated that this bacterium could be a safe and effective alternative bionematicide against the most serious plant-parasitic root-knot nematodes in the genus Meloidogyne.

• 한국응용곤충학회지
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• 제49권3호
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• pp.241-249
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• 2010

Xenorhabdus 및 Photorhabdus 두 곤충병원세균은 곤충의 아이코사노이드 생합성을 억제하여 면역작용을 저하시키는 인자로 알려지고 있다. 본 연구는 이들 세균의 배양액을 이용하여 배추좀나방(Plutella xylostella)을 방제하는 새로운 생화학농약을 개발하려 추진되었다. 두 세균 배양액의 단독 처리는 배추좀나방의 생존력에 뚜렷한 영향을 주지 않았다. 그러나 비티(Bacillus thuringiensis) 생물농약과 혼합하여 처리할 경우 비티 단독 처리에 비해 배추좀나방 4령충에 대해서 현격하게 높은 병원성 증가효과를 주었다. 배양액의 세균 활성을 조사하기 위해 이 세균 배양액을 고온 멸균 및 $0.2\;{\mu}m$ 여과 멸균 처리하였다. 이렇게 처리된 멸균 배양액은 세균이 생존했던 배양액과 차이 없이 비티 생물농약의 병원력을 상승시켰다. X. nematophila 배양액에서 유래된 세 가지 대사물질도 세균배양액과 유사한 비티 병원력 상승효과를 보였다. 야외 배추좀나방 방제 시험에서도 세균배양액은 비티 생물농약의 방제가를 상승시키는 효과를 나타냈다.

• 한국유기농업학회지
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• 제30권1호
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• pp.103-118
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• 2022

Photorhabdus is a bacterial symbiont of entomopathogenic nematodes of the genus Heterorhabditis in the family Heterorhabditidae. Photorhabdus is known to have nematicidal activity in addition to insecticidal activity. P. temperata isolated from Korean indigenous H. megidis Gwangju strain also produced high control efficacy against root-knot nematode Meloidogyne incognita and root-lesion nematode Pratylenchus penetrans. P. temperata has drawn interest as a potential bionematicide for the control of root-knot nematodes thereby. For the registration as an organic agricultural material, the toxicity of P. temperata was assessed by the acute toxicity test in carp (Cyprinus carpio) and acute oral and dermal toxicity tests in Sprague-Dawley rat (Rattus norvegicus) in compliance with the guidelines of the Rural Development Administration (RDA). In the acute toxicity test in fish, neither lethality nor abnormal responses of carp were observed. Body length and weight of carp and changes in DO concentrations and pH values were not significantly different between the treated group and the untreated control. In the acute oral and dermal toxicity tests, clinical signs, abnormal behavior, mortality, and pathological findings were not observed in all the experimental rats. The weight increment of all rats was normal. Acute toxicity results of P. temperata in fish and rats belonged to categories III, IV, and IV of RDA, respectively. Toxicity results of the present study indicated that P. temperata could be a safe and promising bionematicide against root-knot nematodes and root lesion nematode.

• Journal of Applied Biological Chemistry
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• 제55권2호
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• pp.123-127
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• 2012

오늘날 환경친화적인 생물농약을 개발하기 위한 미생물로는 Bacillus thuringiensis 이외에 Photorhabdus, Xenorhabdus 및 Serratia와 같은 곤충병원성 미생물과 Pseudomonas와 같은 식물유용 미생물에 대한 연구가 활발히 진행되고 있다. 본 연구에서는 곤충병원성 미생물인 Photorhabdus temperata M1021 균주를 동결건조법을 이용하여 제제화 하였으며, 동결건조 시 세포보호를 위하여 skim milk, starch, sodium alginate, glucose와 sodium glutamate를 농도별로 첨가하여 동결 건조 후의 세포 생존율을 확인하였다. 그 결과 7% (w/v)의 skim milk가 첨가된 시료에서 가장 높은 63%의 생존율을 나타내었다. 제제화된 동결 건조균을 공기와 접촉시키면서 저온에서 생존율을 측정한 결과 4주 후에도 75% 이상의 생존율을 나타내었다. 또한 제제를 이용한 살충력 시험에서 꿀벌 부채명나방 유충에 대한 주사독성은 $2.0{\times}10^1$ cells/lavar 이상을 주사할 경우 4일 이내에 전체유충이 사멸하는 것으로 나타났으며, $2.0{\times}10^0$ cells/larva의 아주 낮은 농도에서도 50% 이상의 유충사멸 효과를 확인하였다. 본 연구에서 사용된 P. temperata M1021 균주의 동결건조 분말의 뛰어난 살충효과는 보다 현실적인 생물학적 제제로의 개발가능성을 제시하고 있다.

• Journal of Microbiology and Biotechnology
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• 제28권1호
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• pp.12-21
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• 2018

Photorhabdus temperata (PT), a gram-negative bacterium, lives symbiotically within entomopathogenic nematodes. The insecticidal compounds derived from Photorhabdus are used as biopesticides in agriculture. However, the physiological properties are not well characterized. In the course of our screening for neuroprotective and anti-neuroinflammatory substances from natural products, the culture broth of PT showed considerable activities. By activity-guided purification, five anthraquinones, namely, 3-methoxychrysazine (1), 1,3-dimethoxy-8-hydroxy-9,10-anthraquinone (2), 1,3,8-trihydroxy-9,10-anthraquinone (3), 3,8-dihydroxy-1-methoxy-9,10-anthraquinone (4), and 1,3,4-trimethoxy-8-hydroxy-9,10-anthraquinone (5), were isolated from the ethyl acetate fraction of the PT culture broth. Among the isolated compounds, $75{\mu}M$ 3 significantly protected mouse hippocampal neuronal cells (HT22) against 5 mM glutamate-induced cell death via the inhibition of reactive oxygen species production, $Ca^{2+}$ influx, and lipid peroxidation. Additionally, 3 and 4 effectively suppressed the interferon-${\gamma}$-induced neuroinflammation of mouse-derived microglial cells (BV2) at 10 ng/ml, via the reduction of nitric oxide, interleukin-6, and tumor necrosis factor-${\alpha}$. Anthraquinones 3 and 4 derived from the PT culture broth are a potential starting point to discover neuroprotective and anti-neuroinflammatory drug leads. The novel compound 5 is reported for the first time in this study.

• Journal of Microbiology and Biotechnology
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• 제11권4호
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• pp.644-648
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• 2001

The biological control potential of entomopathogenic nematodes (EPN) can be enhanced by improved culture efficiency. Optimization of the media is a key factor for improving in vitro mass production of entomopathogenic nematodes. This study reports the effect of medium concentration. The medium is a combination of carbohydrates, lipids, proteins, sats, and growth factors, on the growth of Heterorhabditis bacteriophora and its symbiotic bacterium Photorhabdus liminescens. The overall optimal medium concentration for nematode recovery, hermaphrodite size, bacterial mass, infective juveniles (IJs) yield, and doubling time was 84 g/l. At this concentration rate, the doubling time of IJs production and the biomass of symbiotic bacteria was 1.6 days and 12.8 g/l, respectively. The maximum yield of $2.4{\times}{10^5}IJs/ml$ was attained within a one-generation cycle (eight days). The yield coefficient was $2.8{\times}{10^6}$ IJs/g medium, and the maximum productivity was $3.1{\times}{10^7}$ IJs per day. Medium concentration affected two independent factors, recovery and hermaphrodite size, which in turn influenced the final yield.

• Journal of Microbiology and Biotechnology
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• 제22권12호
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• pp.1605-1612
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• 2012

The present study concerned the identification and characterization of a novel bacterial strain isolated from entomopathogenic nematodes collected from different regions in Korea. The bacterial isolate M1021 was Gramnegative, bioluminescent, and produced red colonies on MacConkey agar medium. A rod-shaped structure was confirmed by the electron micrograph. Fatty acid composition was analyzed by using the Sherlock MIDI system. The identification was further supported by 16S rDNA sequence analysis, which revealed 96-99% sequence homology with strains of Photorhabdus temperata. The location of the isolated strain of P. temperata in the phylogenetic tree was confirmed and it was named P. temperata M1021. P. temperata M1021 exhibited catalase, protease, and lipase activities when grown on appropriate media supplemented with respective substrates. The culture of P. temperata M1021 exhibited insecticidal activity against the larvae of Galleria mellonella and the activity was the highest after 3-4 days of cultivation with agitating at $28^{\circ}C$ under 220 rpm. Antibacterial activity was also observed against Salmonella Typhimurium KCTC 1926 and Micrococcus luteus KACC 10488.

• 한국응용곤충학회지
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• 제48권3호
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• pp.385-392
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• 2009

Xenorhabdus nematophila (Xn)와 Photorhabdus tempeerata subsp. temperata (Ptt)의 곤충병원세균을 배추좀나방(Plutella xylostella)의 혈강에 주입할 경우 높은 병원력을 보였다. 본 연구는 이들 세균 배양액의 섭식 처리에 따른 배추좀나방에 대한 병원성 유기를 조사하였다. 세균 배양액만을 이용하여 배추좀나방 3령충에 섭식 처리한 결과 뚜렷한 병원성을 유발하지 못하였으나, Bacillus thurigiensis(Bt) 와 혼합 처리하였을 때 높은 Bt 병원성 제고 효과를 나타냈다. 물질 추적을 위해서 이 세균 배양액을 유기 용매를 이용하여 헥산, 에틸아세테이트 및 수용액 추출 분획구로 분리하였다. 대부분이 Bt 상승효과는 에틸아세테이트 추출 분획구에서 나타났다. Thin layer chromatography 분석 결과는 에틸아세테이트 분획구가 대사물질을 포함하고 있으며, 이들이 헥산 또는 수용액 추출 분획구에 포함된 물질과는 상이하다는 것을 나타냈다. 이러한 결과는 이들 곤충병원세균이 Bt 병원성을 제고시키는 물질을 생산하고 배양액으로 분비한다고 제시하고 있다.