FUSION BETWEEN PROTOPLASTS OF PICHIA-STIPITIS AND ISOLATED FILAMENTOUS FUNGI NUCLEI

Nuclei were isolated from mycelium of the filamentous fungi Fusarium m oniliforme and Trichoderma reesei, and fused with protoplasts of the x ylose-fermenting yeast Pichia stipitis using PEG as the fusogenic agen t. Hybrids which were morphologically yeastlike and able to hydrolyze xylan showed a similar chromosomal pattern to the parental yeast when clamped homogeneous electric field (CHEF) electrophoresis was done. Th ese hybrids were isolated and their xylanase activity determined quant itatively. Xylanase activity in the parental fungal species was maximu m at 96 h growth; it reached 796 nkat ml(-1) in the culture medium for F. moniliforme and 898 nkat ml(-1) at 120 h growth for T. reesei. Xyl anase activity in one of the hybrids reached 350 nkat ml(-1) in 9 h. P . stipitis itself showed no xylanase activity. (C) 1997 by Elsevier Sc ience Inc.