Intraspecific Protoplast Fusion of Cellulolytic Fungus, Penicillium verruculosum

Penicillium verruculosum의 종내 원형질체 융합

The conditions for the protoplast fusion of auxotrophic mutants of Penicillium verruculosum were determined. A preparation of commercial enzyme Novozym 234 was used to successfully isolate protoplast from the 20hr old mycelium of P. verruculosum. Under optimal condition, the protoplast yield ranged from 2.4$\times$10$^7$ to 3.0$\times$10$^7$ protoplasts from 400mg of damp mycelia of various auxotrophic mutant strains. The regeneration frequency ranged from 26.6 to 42.4% and the spontaneous reversion frequency of the protoplasts on the regeneration minimal medium was less than 10$^7$. The optimal concentration of PEG 6000 was 20%, and exposure of protoplasts to PEG for 10 min was found to be sufficient for protoplast fusion. Optimal pH of fusion mixture was deter-mined as 5.5 and l0mM of calcium chloride in fusion mixture effectively enhanced the protoplast fusion frequency. Under optimal condition, the fusion frequency between various auxotrophs ranged from 1.8$\times$10$^{-3}$ to 3.5$\times$0$^{-3}$.

Penicillium verruculosum으로부터 유도된 영양요구성 돌연변이주간의 원형질체 융합을 위한 조건을 검토하였다. 20시간 배양한 P. verruculosum의 균사체에 Novozym 234를 처리하여 원형질체를 추출할 수 있었다. 원형질체 생성 최적조건하에서의 원형질체 생성량은 각 영양요구성 변이주의 균사체 400mg 당 2.4~3.0$\times$$10^7$ 수준이었고, 재생율은 36.6~42. 4%, RMM에서의 환원율은 $10^{-7}$ 수준이었다. 원형질체 융합을 위한 PEG6000의 최적농도는 20%였고, PEG 최적처리시간은 10분, CaCl$_2$최적첨가농도는 10mM, 최적 pH는 5.5였으며, 융합 최적조건 하에서의 융합율은 1.8$\times$$10^{-3}$~3.5$\times$0$^{-3}$ 수준으로 나타났다.