Destruxins (Dtxs) are insecticidal cyclic hexadepsipeptides produced by the entomopathogenic fungus Metarhizium anisopliae. Media composition for dtxs production was optimized with industrial grade media. Glycerol and casein peptone were selected as a carbon source and a nitrogen source, respectively. Dtxs production varied with C/N ratios. High yields of dtxs were observed at C/N ratios ranging 0.3 to 1.5, with concentrations mostly higher than 800 mg/L. Low yields were caused by high C/N ratio ranging from 3.0 to 8.0, resulting in less than 500 mg/L. The highest yield of Dtxs was obtained with 2% glycerol and 3% casein peptone, showing 192.2 mg/L of dtx A, 911.1 mg/L of dtx B, and 113.3 mg/L of dtx E, respectively. These results indicated that dtxs production is highly influenced by C/N ratio, especially the content of nitrogen source.

Japanese pine sawyer beetle, Monochamus alternatus Hope (Coleoptera: Cerambycidae) is considered as a serious pest in pine trees. To develop an eco-friendly strategy to manage this forest insect, we collected entomopathogenic fungi from Korean soil and assessed their virulence against the adults of the insect in laboratory conditions. As a result, two isolates with conidial suspension (1.0×107conidia/ml), showed 87% and 90% mortality 12 days after fungal treatment, respectively. We assessed the potential of the fungi-derived destruxin and protease as additives to the fungal isolates, and they showed insecticidal activity via feeding and spraying treatments. Finally, we produced fungal conidia in massive solid cultures and formulated wettable powders, and now studying optimal conditions of oil-based formulation with two isolates. Based on these results, we are evaluating the control efficacy of the fungal agents against M. alternatus in field conditions.

The entomopathogenic fungus Metarhizium anisopliae is one of potent biological control agents against a variety ofinsect pests. In this study, we investigated enzyme production of M. anisopliae strains A and B. They produced extracellularenzymes for degrading the epidermis of Monochamus alternatus, a crucial mediator of the pinewood nematode Bursaphelenchusxylophilus. With Q-TOF MS/MS analysis, 29 kDa protein, a major band on a SDS-PAGE gel, was identified as subtilisin-likeserine protease PR1A. M. anisopliae A produced an extracellular enzyme more efficiently than M. anisopliae B: however,enzyme activities targeted for the cuticle were comparable. Our results suggest that the two strains of M. anisopliae havethe biological potential against M. alternatus with insecticidal protease production.

The entomopathogenic fungus Metarhizium anisopliae B is a powerful biological control agent against Monochamusalternatus, a crucial mediator of the pinewood nematode Bursaphelenchus xylophilus. In this study, production of destruxins(dtxs), insecticidal cyclic hexadepsipeptides, was monitored in the submerged culture of M. anisopliae B. Three typesof dtxs, i.e., destruxin A, B, and E, were produced during the culture. Among the three dtxs, the production yield ofdestruxin A was best, followed by destruxin B and E. Destruxin A production was increased when pH was controlledat 6.0, whereas production of destruxin E was not affected by the pH control. The highest yield of dtxs A, B, and Ewere 16.4, 7.3, and 6.1 mg L-1, respectively. Considering that process for dtxs production has not been optimized, M.anisopliae B has more powerful implication as a biocontrol agent.

Thrips worms and root-knot nematodes occur in a variety of crops, and have shown a great deal of damage to farm income every year, and the damage is increasing every year. In order to solve these problems, a variety of biological materials are used in Korea to develop a control agent. However, there are very few products available that can satisfy the consumer's satisfactory control effect, efficacy, formulation stability and pesticide compatibility. In order to propose a biological control solution to these problems, this study was conducted to develop the optimal bioprocess technology and formulations suitable for the material by transferring the Aspergillus nigerF22 strain, which is effective for root-knot nematodes, at Chonnam National University. This study was conducted to investigate the efficacy of Aspergillus niger F22 20% suspension concentrate (Productname:NEMAFREE), which has excellent efficacy on root nematodes. The packing test result showed about 70-90% control effect. Soil fumigation and disinfection treatments after 4 days of planting were effective. In addition, we have developed a product to control the under powder pupa using Beauveria bassiana ERL836, an insect pathogenic microorganism, which has excellent control effect against resistant insect pupa. The main purpose of this study was to investigate the effect of insect pests on the under poor control of the pupa in the soil. In the pavement test, more than 70%(GR) formulation, which can be treated withch emical pesticides, and it is confirmed that synergy effect is in the control of Thrips worm.

Oxalic acid has a nematicidal activity against the root-knot nematode Meloidogyne incognita. High producer of oxalic acid was isolated, and then named as Aspergillus niger F22. Oxalic acid production was investigated under various temperatures from 20 – 33oC and rotational speeds in 5 L jar fermenters. Yield of oxalic acid increased with decreasing temperature. The highest yield was obtained at 23oC, showing the yield of oxalic acid of 8.7 g/L, whereas oxalic acid production was least at 33oC. At 20oC, the yield was lower than that of 23oC. At a rotational speed of 300 rpm, serious oxygen depletion was present from 48 - 72 h, resulting in low productivity of 26.2 mg /L·h. When a rotational speed was set at 600 rpm, dissolved oxygen tension was over 40% and oxalic acid production increased up to approximately 55%. Viscosity during the culture differed with temperatures. Viscosity increased with the increment of temperatures. When A. niger F22 was cultured at 23oC, viscosity was 810 cP, which was favorable for oxalic acid production.

A nematode, which showed entomopathogenicity, was isolated from Exomala orientalis in Korea, and then identified as Rhabditis blumi. Pathogenicity of R. blumi was evaluated against major cruciferous insect pests, including Artogeia rapae, Mamestra brassicae, and Plutella xylostella. In Petri-dish tests, insect mortality was dose and time dependent, which increased with dose (0–80 dauer juveniles/larva) and time increments. In greenhouse tests, P. xylostella larvae were most susceptible to nematodes, with insect reduction rate of 88.0 %. The rate varied with vegetable species and persistence time of live nematodes on vegetable leaves after spraying. The aeration rate was an important parameter for cultivation of the nematode R. blumi. A sufficient DOT level in the culture using an air-lift bioreactor should be maintained. The nematode growth rate increased with an increasing DOT level and/or bacteria uptake rate. The maximum nematode yield of 1.75 x 105 per ml was obtained under an aeration rate of 6 vvm.

Biological control has been tried for integrated pest management. It is often comparable, safe, and environment-friendly, making itself an alternative for chemical agents. Filamentous microorganisms, i.e., fungi and streptomystes, produce many kinds of useful metabolites, and some of them have been developed as a biocontrol agent. However, they still have a long way because of the concern of manufacturing cost. Therefore, process development was intensively studied to meet cost-effectiveness. Operating conditions of bioreactor, e.g., agitation and aeration, had an effect on biological and physiological responses such as mycelial morphology, oxygen and nutrient transfer. Understanding relationship between operating parameters and microbial responses in terms of growth, substrate and oxygen consumption, and production yield was critical for process development. This study dedicated to build strategies for mass production of biological control agent using aerobic filamentous microorganisms.

표고버섯좀나방(Morophagoides moriutii)은 최근 버섯 에 심각한 피해를 주는 해충으로 유충이 골목이나 종균, 자실체를 직접 가해하여 생산량을 감소시키고 상품성을 저하 시킨다. 표고버섯좀나방의 환경 친화적 방제에 이용 할 수 있는 가능성을 알아보기 위하여 국내 토양에서 탐 색된 토착 곤충병원성 선충 Steinernema carpocapsae GSN1 계통의 접종 농도별 병원성, 침입수, 증식수를 표고 버섯좀나방의 령기에 따라 조사하였다. 선충의 표고버섯 좀나방에 대한 병원성은 접종농도가 높을수록 증가하였다. 표고버섯좀나방 2령충, 3령충에서 유충 한 마리당 선충 감염태 유충(3령충) 80마리 접종부터 100%의 높은 병원 성을 나타내었고, 표고버섯좀나방 4령충은 한 마리당 선 충 감염태 유충 40마리 접종부터 100%의 치사율을 나타 내었다. 선충의 표고버섯좀나방 유충 체내로의 침입수는 접종 농도와 령기가 높을수록 선충의 침입수도 증가 하였 다. 선충 감염태 유충 5마리 농도 처리에서는 2령충 1.3마 리, 3령충 1.7마리, 4령충 1.8마리 였으나, 160마리 농도 처리에서 2령충 12.3마리, 3령충 21.1마리, 4령충 22.5마 리로 조사 되었다. 끝으로 표고버섯좀나방 유충 한 마리 당 침입한 선충의 증식수는 같은 령기에서는 선충의 접종 농도가 많아질수록 증식수가 증가하였다. 또한 표고버섯 좀나방의 령기에 따라 선충 증식수의 차이는 많았는데, 선충 감염태 유충 160마리 처리농도에서는 각각 표고버 섯좀나방 2령충이 6,335마리, 3령충이 21,660마리, 4령충 이 88,700마리로 조사되었다. 따라서 토착 곤충병원성 선 충 S. carpocapsae GSN1 계통은 표고버섯좀나방의 생물 적 방제를 위한 방제제로 활용할 가능성이 높음을 알 수 있었다.

김치 과숙에 관여하는 균주와 대장균의 성장을 억제하는항균활성을 지닌 균주를 김치로부터 선발하고자 하였다. 전국 6개도의 배추김치 10종으로부터 분리한 500여개의 균주를 대상으로 김치의 과도한 산생성에 관여할 것으로 예상되는 P. pentosaceus, Lb. sakei, Lb. plantarum과 원·부재로로부터 초기에 유입되는 대장균군의 저감화를 위하여 E.coli에 대한 항균활성을 살펴본 결과, 2-7 30 균주가 모든지시균주에 대해 뚜렷한 생육저지환을 나타내었다. 지시균주들에 대해 일부 항균활성을 나타낸 15균주를 최종적으로선발하여 동정한 결과, Lb. sakei, Lb. plantarum, Lb. brevis,Lb. paraplantarum, Leu. citreum으로 각각 동정되었다.

호박꽃과실파리(Bactrocera scutellata Hendel)의 성충 수명과 산란수를 7개 온도(15, 18, 21, 24, 27, 30, 33 ± 1.0℃, RH 65 ± 5%, 14L: 10D)에서 조사하여 생명표를 작성하였다. 온도별 성충수명은 21℃에서 수컷이 138.0일 암컷이 131.2일로 가장 오래 살았으며, 21℃를 기준으로 저온부와 고온부로 갈수록 수명이 급격히 감소하였다. 온도별 암컷은 18℃이하의 온도에서 산란을 하지 않았으며, 33℃에서는 짝짓기가 가능한 시기까지 살지 못하고 모두 사망하였다. 짝짓기한 암컷의 총 산란수는 111.4개, 일일 산란수는 1.0개로 24℃에서 가장 많은 산란수를 보였고 순증가율(Ro)은 21℃에서 52.27로 가장 높은 수치를 나타냈다. 내적자연증가율(rm)은 27℃에서 0.07을 보였으며, 배수기간(λ)은 27℃에서 10.02로 가장 짧았다. 기간증가율(Dt)은 27℃에서 1.07로 가장 큰 값을 보였고, 평균세대기간(T)은 27℃에서 50.39였다.

Rhabditis blumi, isolated from Exomala orientalis, is a necromenic type of nematode that possesses several attributes of a potential biological control agent such as ease in culture conditions, high rates of reproduction and virulence, short life cycle and rapid multiplication etc. Pathogenicity of R. blumi was tested against 5 coleopteran species and 5 lepidopteran species. All insect larvae were susceptible to R. blumi, showing over 60% mortality except for Holotrichia kiotoensis and Ectinohoplia rufipes. The highest mortality was observed in Plutella xylostella (88%), followed by Artogeia rapae, Exomala orientalis, Spodoptera litura and Anomala rufocuprea (over 70%). Reproductive capacity of R. blumi differed from each insect species, ranging from 17 to 656 dauer juveniles/mg of insect larva. Dauer juvenile production was most in Plutella xylostella larvae, producing 656 dauer juveniles/mg of host body weight, followed by E. orientalis, H. kiotoensis, and A. rapae larvae (over 100 dauer juvenile per mg).

The quality characteistics and kimchi processing ability of the kimchi cabbage cultivar ‘Cheonjincheongmayup’ (CC) were analyzed and compared with those of the ‘Chunkwang’ (CK) cultivar. The head weight of CC was lower than that of CK, and the head length of CC was larger than that of CK. CC had narrower and longer mid ribs than CK. Furthermore, the head formation index of CC was lower than that of CK. The firmness and soluble solid content were higher in CC than in CK. The salinity of Cheonjincheongmayup kimchi (CCK) was 2.89-3.02%, which was higher than 1.94-2.10% salinity measured in Chunkwang kimchi (CKK). The initial titratable acidity in CCK was higher than that of CKK, but increasd more slowly during storage. CCK was firmer than CKK; lactic acid bacteria in CCK was lower than in CKK initially, but increased more in CKK than in CCK after six weeks of storage. We found that CC was suitable for making Makkimchi because of its long and narrow mid ribs, saltiness, and slow fermentation. CC should be improved as less hot spicy and less hard texture to use a Makkimchi material.

본 연구는 초저온 액체 침지식 급속 냉동으로 동결된 돈육 등심에 적합한 급속 해동방법을 선정하고 과냉각 저장이 냉동-해동 돈육의 미생물학적, 이화학적 및 관능적 품질변화에 미치는 영향을 살펴보았다. 4와 10℃ 송풍식 해동과 4와 10℃유수식 해동은 냉동 돈육 시료가 해동이 완료되는 약 290-750분 소요되었지만 27.12 MHz 라디오파 해동은 약 20분으로 가장 신속하게 돈육을 해동시켜 저장실험에 필요한 냉동 돈육의 급속 해동방법으로 선정하였다. 한편 -1.5--5℃로 24시간 냉각 처리 후 돈육 횡단면의 미세구조 분석 결과, -1.5℃에서 냉각 처리된 시료의 표면과 중심부는 동결에 의한 조직 손상이 발생하지 않았음을 확인하여 -1.5℃를 과냉각 저장 온도로 선정하였다. 저장 중 대조구인 신선육과 비교하여 냉동-해동 처리된 돈육에서 발생한 드립감량은 유의적으로(p<0.05) 높은 경향을 보였지만 -1.5℃ 과냉각 저장이 돈육의 드립감량 증가를 억제하였다. 또한 4와 15℃ 저장과 비교하여 -1.5℃ 과냉각 저장은 대조구와 냉동-해동 처리구의 TVBN과 TBARS 함량 증가, Hunter a* 값 감소와 b* 값 증가를 억제하는 효과를 보였다. 15℃ 저장 4일 후 대조구와 냉동-해동 처리구의 총 호기성 세균수는 9 log CFU/g 이상으로 급격히 증가하였다. 반면 -1.5℃ 저장 10일 후 대조구와 냉동-해동 처리구의 총 호기성 세균수는 각각 5.62와 4.43 log CFU/g으로 관찰되었다. -1.5℃ 저장 10일 동안 대조구와 냉동-해동 처리구의 대장균군과 효모 및 곰팡이 수는 저장 초기 수준으로 유지하거나 다소 감소하였다. 관능평가 결과에 있어서 4와 15℃ 저장에 비해 -1.5℃ 저장한 대조구와 냉동-해동 처리구는 모든 관능평가 항목에서 저장 중 유의적으로 높은 값을 유지하였다(p<0.05). 따라서 라디오파 유전가열 해동은 냉동 돈육 등심의 해동 과정 중 상전이 구간을 빠르게 통과함으로써 급속해동이 가능하였으며 -1.5℃ 과냉각 저장이 냉동-해동 처리 된 돈육에 얼음결정 형성 없이 품질 유지 및 미생물 생장지연에 효과적인 것을 확인하였다.