• 한국생물공학회:학술대회논문집
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• 2001.11a
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• pp.906-909
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• 2001

In order to investigate fatty acid contents and effects of cell growth on the production of an extracellular protease and toxicity of exotoxin, several symbiotic bacteria with highly effective toxins were isolated from seven species of entomopathogenic nematodes belong in Steinernematidae(Steinernema glaseri XR-DR, S. glaseri XR-NC, S. glaseri XR-MK, S. carpocapsae XR-PC, S. maticola XR-MO, S. Longicaudum XR-LC) and Heterorhabditidae sp.(Heterorhabditis bacteriophora XR-HY). In the cell growth and exotoxin toxicity, XR-PC and XR-MK were superior to other species when cultured in vitro. The protease activity of XR-DR was remarkable compared to other species. In the case of XR-HY, the protease activity increased in parallel with cell growth. Interestingly the fatty acid contents of XR-PC and XR-HY were significantly different from those of other species 12:0, 14:0, 13:0 iso, 16:1 cis 5 and 17:0 cyclo.

• 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.

• Korean journal of applied entomology
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• v.49 no.4
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• pp.409-416
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• 2010

An entomopathogenic bacterium, Photorhabdus temperata ssp. temperata (Ptt), suppresses insect immune responses and facilitates its symbiotic nematode development in target insects. The immunosuppressive activity of Ptt enhances pathogenicity of various microbial pesticides including Bacillus thuringiensis (Bt). This study was performed to select a cheap and efficient bacterial culture medium for large scale culturing of the bacteria. Relatively cheap industrial bacterial culture media (MY and M2) were compared to two research media, Luria-Bertani (LB) and tryptic soy broth (TSB). In all tested media, a constant initial population of Ptt multiplied and reached a stationary phase at 48 h. However, more bacterial colony densities were detected in LB and TSB at the stationary phase compared to two industrial media. All bacterial culture broth gave significant synergism to Bt pathogenicity against third instars of the diamondback moth, Plutella xylostella. Production of bacterial metabolites extracted by either hexane or ethyl acetate did not show any significant difference in total mass among four culture media. Reverse phase HPLC separated the four bacterial metabolites, which were not much different in quantities among four bacterial culture broths. This study suggests that two industrial bacterial culture media can be used to economically culture Ptt in a large scale.

• Journal of Applied Biological Chemistry
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• v.55 no.2
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• pp.123-127
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• 2012

In order to develop eco-friendly biopesticide, an entomopathogenic bacterium Photorhabdus temperata M1021 has been lyophilized via freeze-drying along with protective agents such as skim milk, starch, sodium alginate, glucose and sodium glutamate to protect cells from lysis. Freeze-drying powder of P. temperata M1021 containing 7% skim milk (w/v) showed highest survival rate of 63% among all the protective agents used in trials. Furthermore, the freeze-dried microbial powder showed 75% of survival rate after stored at $4^{\circ}C$ for 4 weeks at air contact conditions. Injection toxicity of the freeze-dried sample was tested against larvae of Galleria mellonella. A dose of $2.0{\times}10^1$ cells of P. temperata M1021 killed 100% of the G. mellonella larvae within 4 days after injection. Moreover, $2.0{\times}10^0$ cells caused 50% mortality within the 4 days after injection. Freeze-dried P. temperata M1021 strains exhibited effective insecticidal activity and could be a better candidate for being used as a biopesticide.

• Korean journal of applied entomology
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• v.44 no.1 s.138
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• pp.21-30
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• 2005

Feeding behavior of foraging ants including visiting numbers, species, and preference on insect cadavers killed by entomopathogenic nematodes <(Heterorhabditis sp. KCTC 0991BP (He) and Steinernema carpocapsae KCTC 0981BP (Sc)> and their symbiotic bacteria was investigated in Dongrae Benest Golf Club, Anyang Benest Golf Club, Gapyung Benest Golf Club and Ulsan Golf Club. The number of ants, kinds and numbers of cadavers taken away by ants were different depending on killing method, golf club and site within the golf courses (fairway and rough). The feeding preference of ants was the lowest on cadavers killed by He. At Dongrae Benest Golf Club Lasius japonicu ($75{\pm}5\%$) and Monomorium floricola ($10\%$) took away cadavers only at the rough. The visiting rate of ants was $85{\pm}6\%$ at the rough, but none at the fairway by 16 hours. The taken rate of cadavers by ants was the lowest on He-killed cadavers representing $16.7\%$ compared with $40.0\%$ on Sc-killed cadavers, $53.3\%$ on fenitrithion-killed cadavers, and $56.7\%$ on natural dead cadavers by 12 hours. At the rough of hole 6 in Anyang Benest Golf Club, Tetramorium tsushimae ($33{\pm}12\%$), Pheidole fervida ($17{\pm}15\%$), Camponatus japonicus ($10\%$), Formica japonica ($7{\pm}6\%$), Paratrechina flavipes ($3{\pm}6\%$), and Crematogaster matsumurai ($3{\pm}6\%$) took away cadavers, but $23{\pm}15\%$ of cadavers were not visited by ants. Ants took away $40\%$ of Sc-killed cadavers, $16.7\%$ of frozen-killed cadavers, and $3.4\%$ of He-killed cadavers. The number of visiting ants was low at the hole 9 of Cherry course in Gapyung Benest Golf Club and only Tetramorium tsuhimae and Paratrechina flavipes were found from one site. The density of entomopathogenic nematodes did not influence ant visiting on cadavers, but burying affected ant visiting. Although ants took away unburied cadavers, buried cadavers were taken away at the hole 6 of Dongrae Benest Golf Club by 16 hours. Ant visiting had the same tendency on symbiotic bacterium-treated biscuit as nematode-killed cadavers. The visiting was less on biscuit inoculated by Photorhabdus sp., a symbiotic bacterium of He than on biscuit inoculated by Xenorhabdus nematophila, a symbiotic bacterium of Sc.

• Korean journal of applied entomology
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• v.51 no.3
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• pp.245-253
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• 2012

Benzylinedeneacetone (BZA) is a bacterial metabolite which is synthesized by at least two entomopathogenic bacteria, namely Xenorhabdus nematophila and Photorhabdus temperata subsp. temperata. It has been shown to possess inhibitory effects on insect cellular and humoral immune responses as well as antimicrobial activities against various species of bacteria and fungi. However, its relatively high phytotoxicity, and nonsystematic effect have thus far prevented its development into an optimal pesticide. This study screened five different BZA derivatives in order to select an optimal compound, which would have relatively high solubility and low phytotoxicity while retaining sufficient degrees of the immunosuppressive and antimicrobial activities associated with BZA. Hydroxylation of the benzene ring of BZA was found to significantly suppress its immunosuppressive and antimicrobial activities. Transformation of the ketone of BZA by carboxylation also suppressed the inhibitory activities. However, a shortening of the aliphatic chain of BZA into acetate form (4-hydroxyphenylacetic acid: HPA) did not decrease the inhibitory activity. HPA also showed much less phytotoxicity against the hot pepper plant Capsicum annuum, when compared to BZA. This study identified an optimal BZA derivative, which exhibited relatively little phytotoxicity, but retained a high degree of inhibitory activity to suppress insect immune responses and antimicrobial activities against plant pathogens.

• The Korean Journal of Soil Zoology
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• v.9 no.1_2
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• pp.1-5
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• 2004

Insect pests and their natural enemies of Hibiscus Linne (Malvaceae) were investigated from March 2002 to November 2004. Fourteen insect pest species of 9 families in 5 orders were collected from Hibiscus syriacus: 5 species in Homoptera, 3 species in Lepidoptera, 2 species in Coleoptera, 1 species in Orthoprera, 1species in Hemiptera, 1 spedies in Acarina, and 1 species in Stylommatophora. Especially, Aphis gossypii Glover (Aphididae), Anomis megogona Walker(Noctuidae) and Tetranychus urticae Koch (Tetranychidae) were very important species because of their increasing daminge. The highest donsities were observed from May to June in August in Tetranychus urticae. As the enemies and ento-mopathogens of insect pests on Hibiscus syriacus, 1 species of bacteria, 3 species of fungi, 1 species of fungi, 1 species of Hemiptera, 1 species of Coleoptera, 2 species of Hymenopetera, 2 species of Diptera, and 1 species of Acarina were investigated. As the predators and parasitoids of Aphis gossypii, Aphidoletes aphidoletes aphidimyza Rondani (Cecidomyiidae), Meliscaeva cinctella Zetterstedt (Syrphidae), Harmonia axyridis Pallas (Coccinellidae), and Aphidius gifuensis Ashmead (Braconidae), entomopathogenic fungi, Vericillium lecani naturalis strain (Moniliaceae) and Beauveria bassiana naturalis strain strain (Hypocreaceae) were observed and Bacillus thuringiensis naturalis strain (Bacillaceae), B. bassiana, Metarhizium anisopliae naturalis strain (Hypocreaceae), predators of Tetranychus urticae, Amblyseius sp. (Phytoseiidae), and Orius sp. (Anthocoridae) were observed.

• The Korean Journal of Pesticide Science
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• v.13 no.3
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• pp.185-189
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• 2009

A monoterpenoid compound, benzylideneacetone (BZA), is a metabolite of an entomopathogenic bacterium, Xenorhabdus nematophila. Its primary biological activity is an inhibitor of phospholipase $A_2$, which catalyzes the committed step of biosynthesis of various eicosanoids that are critically important to mediate insect immune responses. When BZA was applied to two-spotted spider mite, Tetranychus urticae, it exhibited a dose-dependent mortality in leaf-disc assay. Subsequently BZA was tested against T. urticae infesting apples in a field orchard, in which it showed a significant control efficacy, which was not statistically different with that of a commercial acaricide. BZA also had significant antibacterial activities against three species of plant pathogenic bacteria when it was added to the bacterial cultures, in which it showed the highest inhibitory activity against a bacterial wilt-causing pathogen, Ralstonia solanacearum. The bacterial pathogen caused significant disease symptom to young potato plants. However, BZA significantly suppressed the disease occurrence. This study suggests that BZA can be used to develop a novel crop protectant to control mite and bacterial pathogen.

• Research in Plant Disease
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• v.23 no.2
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• pp.114-149
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• 2017

World-wide crop loss caused by insect pest and nematode reaches critical level. In Korea, similar crop loss has been gradually augmented in the field and greenhouse due to continuous crop rotation. The current methods on controlling herbivorous insects and plant parasitic nematodes are mostly depended on agro-chemicals that have resulted additional side-effect including occurrence of resistant insects and nematodes, environmental contamination, and accumulation in human body. To overcome the pitfalls, microbe-based control method have been introduced and applied for several decades. Here, we revised biological control using by the bacteria, fungi, and virus in order to kill insect and nematode and to attenuate its virulence mechanism. The introduced microbes mainly secreted out the hydrolysing enzymes and toxic compounds to target host membrane or cell wall directly. Indirectly, the microbe-triggered plant innate immunity against insects and nematodes was also reported. In conclusion, we provide a new frontier of microbe-based environmentally friendly procedure and effective methods to manage insects and nematodes.

• Korean journal of applied entomology
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• v.62 no.4
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• pp.277-285
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• 2023

The onion moth, Acrolepiopsis sapporensis, was monitored in the farms cultivating the welsh onion, Allium fistulosum, using sex pheromone from transplantation to harvest. Two occurrence peaks were observed at early June and late July after the overwintering population. However, the population sizes were varied among different years and the cultivating environments. To effectively control A. sapporensis with microbial pesticides, different Bacillus thuringiensis strains were screened to select B. thuringiensis kurstaki (BtK). To enhance the insecticidal virulence of BtK, the culture broth of Photorhabdus temperata temperata (Ptt) was added to the BtK. This mixture of two entomopathogenic bacteria was called 'BtPlus', which was superior to BtK alone in the insecticidal virulence. The enhanced virulence was explained by the immunosuppressive activity of the secondary metabolites contained in the Ptt extract. The metabolites inhibited both cellular and humoral immune responses of A. sapporensis, resulting in the enhanced virulence of BtK. These results suggest that A. sapporensis occurs in the welsh onion fields and the resulting economic damage would be effectively prevented by BtPlus application.