Strain improvement in T. reesei

One of the key issues in fungal strain breeding is the generation of improved producer strains in terms of enzyme yield. In the past this has traditionally been achieved by a combination of classical mutagenesis during which the fungus was exposed to different mutagens such as X-rays, y-rays, UV rays, or chemicals, including N-methyl-N-nitro-N — nitrosoguanidine (NTG) and ethyl methanesulfonate (EMS), in combination with different screening procedures to isolate cellulase-overexpressing strains. Classical mutagenesis is a common tool that has been successfully applied for many microorganisms, including fungi, to improve the production of various industrial enzymes (glucoamylase, lipase or cellulase). A prerequisite in such strain improvement programs is, of course, that the microorganism already produces the enzyme(s) of choice. It is a peculiarity of T. reesei that all these cellulase high-producing strains generated by classical mutagenesis and used today in research or by the major enzyme manufacturers are derived from strain QM6a from the Solomon Islands. However, the availability of sophisticated gene manipulation methods and the recent decoding of the genome sequence of T. reesei enable us to introduce molecular genetic tools into such programs. One approach to better understand the biology underlying cellulase hyperproduction is the analysis of improved producer strains derived from classical mutagenesis programs. Until recently, only a few data were available on the genomic alterations that occurred in the strains undergoing strain improvement procedures. With the publication of the genome sequence of strain QM6a and the development of high-throughput methods such as massively parallel DNA sequencing and comparative genomic hybridization (CGH), it is now possible to identify the genomic changes that occurred in the different mutant lines.

Добавить комментарий

Ваш e-mail не будет опубликован. Обязательные поля помечены *