Although many eukaryotes are able to reproduce sexually, as much as 20% of fungal species had been thought to reproduce exclusively by asexual means. However recent studies have revealed that sex occurs even in some of the supposedly asexual species. For example, sexual capability was recently shown for the fungus "Penicillium roqueforti", used as a starter for blue cheese production. This finding was based, in part, on evidence for functional mating type (MAT) genes that are involved in fungal sexual compatibility, and the presence in the sequenced genome of most of the important genes known to be involved in meiosis. "Penicillium chrysogenum" is of major medical and historical importance as the original and present-day industrial source of the antibiotic penicillin. The species was considered asexual for more than 100 years despite concerted efforts to induce sexual reproduction. However, in 2013, Bohm et al. finally demonstrated sexual reproduction in "P. chrysogenum".