선행연구에서 근권 토양으로부터 분리된 Lysobacter antibioticus HS124 (HS124)는 lytic enzyme으로써 chitinase, gelatinase, lipase 및 protease 등의 효소와 항생물질인 4-hydroxyphenylacetic acid (4-HPAA)를 생성하였다. 본 실험에서는 HS124를 이용하여 배추좀나방 (diamondback moth, Plutella xylostella L.) 3~4령 유충의 살충활성을 검정하였다. HS124 배양액을 배추좀나방 유충에 처리하였을 때 유충은 파괴되어 분해되었다. HS124가 생성하는 4-HPAA를 유충에 처리하였을 때 처리 농도가 높을수록 살충율은 증가하였으며, HS124 배양액에 Tween 80을 첨가하였을 때 첨가하지 않은 처리구보다 살충율이 1.4배 높았다. 한편 화학 살충제 (IS), HS124 배양액 (HS124), 식물추출물 (매직파이; MP), HS124 배양액+식물추출물 (HS124+MP) 및 멸균수 (SDW)를 이용하여 배추좀나방 유충의 살충율을 검정하였다. HS124+MP 처리구에서 가장 높은 살충율을 나타내었고, IS, MP, HS124 및 SDW 처리구 순으로 살충율이 감소하였다. HS124 처리구는 대조구인 멸균수처리구보다 31% 높은 살충율을 나타내었고, HS124+MP처리구 보다 40% 낮은 살충율을 나타내었다. 이러한 결과로 보아 항생물질과 다양한 lytic enzyme을 생성하는 L. antibioticus HS124 배양액과 식물추출물의 혼합제제는 배추좀나방의 생물학적 방제제로써 가치가있다고 사료된다.
Lysobacter antibioticus HS124 was isolated from rhizosphere soil in previous experiments, which produced lytic enzymes such as chitinase, gelatinase, lipase and protease. In addition, HS124 released an antibiotic compound, 4-hydroxyphenylacetic acid (4-HPAA). When larvae of P. xylostella was treated with HS124 culture broth, its body was destroyed, and degraded with the increase of incubation time, yielding glycine which was detected from HS124 culture broth. When 4-HPAA produced from HS124 was sprayed, larvae mortality increased with increasing concentration of 4-HPAA. When HS124 culture supplemented with Tween 80 was sprayed, its insecticidal activity against larvae was approximately 1.4 times higher compared to the culture without Tween 80. Insecticide (IS), HS124 culture broth (HS124), Magic-pi (MP) and HS124 culture broth+Magic-pi (HS124+MP) were each treated against larvae of P. xylostella to investigate their insecticidal effect where sterile diluted water (SDW) was used as a control. The highest mortality of larvae was found in HS124+MP, followed by IS, MP, HS124 and SDW respectively. Mortality of larvae in HS124 was 31% higher than that in SDW, but 41% lower than that in HS124+MP, meaning that both enzymes and antibiotics produced from HS124 may synergistically act as active agents with plant extract containing neem oil and turmeric in HS124+MP treatment. These results suggested that L. antibioticus HS124 together with plant extract can be one of candidates for biocontrol agents against Plutella xylostella.
