Cell Fusion of Cellulolytic Fungi, Aspergillus sp. HB1

섬유소 분해균 Aspergillus sp. HB 1의 세포융합에 관한 연구

The author isolated high cellulolytic fungi from natural sources and determined optimal condition of protoplast formation and fusion as fundamental step for improvement of the isolated it's cellulolytic ability. Three different cellulolytic fungi, such as Aspergillus sp., Penicillium sp. and Trichoderma sp., were isolated from soil. Their cellulolytic activities were compared with that of Aspergillus niger which was useful industrially and had cellulase activity. It was Aspergillus sp. that showed the highest activity of all these four fungi. And then it was followed by Penicillium sp., Trichoderma sp., and Aspergillus niger in order. An auxotrophic mutant of Aspergillus sp. was obtained by UV mutagenesis method. Having try to produce protoplast from mycelia, the author found that ${\beta}-glucuronidase$, at pH 6.0, was effective cell-wall lytic enzyme. And the optimal concentration of this enzyme was 5,000 unit/ml. Regeneration rates of wild type, met. auxotroph and arg. auxotroph, in presence of osmotic stabilizer, were 7. 0%, 7. 5% and 5.2%, respectively. PEG with M.W. 6,000 was effective stimulator for protoplast fusion in the concentration of 30% (W IV). In such a condition, we obtained 1.2% cell fusion rate.

자연계에서 섬유소분해능이 우수한 균을 분리하였고 섬유소분해능을 더욱 증진시키기 위한 기초단계로서 그 분리균주의 원형질체 생성과 융합의 최적조건을 조사하였다. 토양에서 채취한 시료로부터 섬유소분해능력이 우수한 Aspergillus sp., Penicillium sp., Trichoderma sp., 3균주를 분리 동정하였고 산업적으로 유용한 균주이며 cellulase activity가 있는 Aspergillus niger를 비교균주로 선택하여 각각의 효소활성도를 비교 조사한 결과, Aspergillus sp.가 가장 좋은 효소활성도를 보였으며 그 다음 Penicillium sp., Trichoderma sp., 그리고 Aspergillus niger 순이었다. 효소활성도가 가장 좋은 Aspergillus sp.에 자외선$(12erg/sec/mm^2)$을 4 분 30초 동안 조사하여 영양요구성 변이주를 유도, 분리하였다. 세포벽분해효소로는 pH6.0에서 ${\beta}-glucuronidase$가 효과적이었고 그 효소를 농도별로 처리해본 결과 5, 000unit/ml가 최적농도이었다. 재생률은 삼투안정제로 0.6M KCI을 사응하여 pH6.0에서보았을 때 야생형은 7.0%, met. 영양요구주는 7.5%, arg. 영양요구주는 5.2%이있다. 영양요구성변이주간의 원형질체융합에 필요한 PEG는 분자량이 6,000인 것이 좋았으며 최적농도는 $30^{\circ}C$ 이었다. 이때 융합율은 1.2%까지 획득하었다.