IMPROVED PRODUCTION OF TRICHODERMA-HARZIANUM ENDOCHITINASE BY EXPRESSION IN TRICHODERMA-REESEI

The chromosomal endochitinase gene (ThEn-42) of the mycoparasite fungu s Trichoderma harzianum P1 was isolated and overexpressed in the filam entous fungus Trichoderma reesei under the promoter of the major cellu lase gene cbh1. The host strain RutC-30 did not produce any endogenous endochitinase activity. The prepro region of the T. harzianum endochi tinase was correctly processed in T. reesei. No differences in express ion were observed when the prepro region was replaced with the CBHI si gnal sequence. Shake flask cultivation yielded 130 mg of active enzyme per liter, which in terms of activity represents about a 20-fold incr ease over the endochitinase activity produced by T, harzianum. The pre sence of multiple copies of the expression cassette in the transforman t resulted in limitation in transcription and/or regulation factors ne eded for full activity of the cbh1 promoter, although this was not the major limiting factor for higher expression of endochitinase. The end ochitinase was very sensitive to an acidic protease at the late stages of T. reesei cultivation. T. reesei RutC-30 appeared to be tolerant o f the endochitinase and can be used as a production host for this enzy me, which has antifungal activity toward plant pathogens.