초록
전라북도 동충하초 재배농가 오염균은 Paecilomyces farinosus(Holm ex S. F. Gray) Brown ＆ Smith로 동정되었으며 특성은 다음과 같다. 분리$.$균은 감자한천배지 상에서 24$\pm$1$^{\circ}C$, 14일간 배양한 결과 배지 앞면은 흰색, 뒷면은 노란색을 띠고 직경 19mm로 생장하였다. 균사 직경은 1.2-1.9$\mu\textrm{m}$이며 분생자병은 투명하며 직경 1.3-1.5$\mu\textrm{m}$이다. phialides는 윤생형으로 분생자병으로부터 2-4개가 형성되며 기부는 부풀어 있고 상단부로 갈수록 폭이 좁아지는 호리병형으로 3.8-5.8${\times}$1.5-1.8$\mu\textrm{m}$이다. phialides의 neck은 직경 0.6-0.8$\mu\textrm{m}$이며, 분생 포자는 분생자형성세포로부터 연쇄상으로 발생하며 타원형 혹은 방추형이며 크기 1.8-2.4${\times}$l.1-1.4$\mu\textrm{m}$이다. 균 농도 1${\times}$$10^{8}$ conidia/$m\ell$로 경피 접종된 누에의 감염률은 41.3%이었으며, 분생자병속 형성률은 23.7%이었다. 균 접종 5-9일 후 누에피부 상에 검은 반점이 형성되었으며, 보호기간 3-4일 후 감염누에 표피는 흰색의 균사에서 점차 노란색 균사로 덮이며, 분생자병속이 발생되었다 분생자병속은 노란색, 선단부로 갈수록 흰색을 나타내었으며 4-6mm 길이로 표피에 한 개에서 다수가 형성되었다. 또한 성숙된 분생자병속의 끝부분에는 분지 후 흰색의 분생포자가 다량 발생하였다.
A infectious fungus (J131) recently isolated from artificial cultivation farms of Paecilomyces tenuipes is known to cause a great yield loss and deterioration of products. In this study, its occurrence and characterization were made. The isolate (J131) was identified as Paecilomyces farinosus (Holm ex S. F. Gray) Brown ＆ Smith. Colonies of the isolate on PDA grew moderately fast, attaining a diameter of 19mm within 14 days at 24${\pm}$1$^{\circ}C$. Vegetative hyphae are smooth-walled and hyaline. Conidiophores mainly arose from the submerged mycelium, usually measuring 1.3-1.5$\mu\textrm{m}$ wide and consisted of verticillate branches with whorls of 2 to 4 phialides. Phialides of 3.8-5.8${\times}$1.5-1.8 $\mu\textrm{m}$, with a swollen basal portion tapered into a distinct neck of about 0.6-0.8 $\mu\textrm{m}$ wide. Conidia arisen from the phialides, were ellipsoidal to fusiform, smooth-walled, hyaline, 1.8-2.4${\times}$1.1-1.4$\mu\textrm{m}$. .When silkworm larvae were injected with concentration of 1${\times}$10$\^$8/ conidia/$m\ell$ of infectious fungus J131, infection rate was 41.3％ and synnemata formation rate was 23.6％. Black spots were appeared on the surface of silkworm larvae in 5-9 days after injection. The surface of larvae was covered with hyphae which were gradually turned into yellow from white color during the incubation period of 3-4 days. 1 to several 4-6mm long synnemata of yellow or orange color were formed on the surface. The matured synnemata were ramified from its end and produced much conidia of white color.
