Genetic modification ofCandida maltosa, a nonpathogenic CTG species, revealsEFG1function

ABSTRACT Candida maltosa is closely related to important pathogenic Candida species, but it has been rarely isolated from humans. Therefore, through comparative studies, it could be a powerful model to understand the pathogenicity underpinnings of Candida species. To facilitate studying C. maltosa at a molecular level, we built a cohesive genomic sequence composed of 45 scaffolds, a substantial improvement from the thousands of contigs of the available draft. Comparison with C. albicans and C. tropicalis revealed a reduction in the total number of genes in C. maltosa . However, gene loss seems not to be associated to its avirulence given that most pathogenicity genes were also present in C. maltosa . To genetically edit C. maltosa we generated triple auxotrophic strains so that gene deletions can be performed as has been routinely done in pathogenic species. As a proof of concept, we generated gene knockouts of Efg1, a transcription regulator involved in filamentation and biofilm formation in pathogenic species. Although in C. maltosa Efg1 also played a role in these processes, it seems to rather be a repressor of filamentation. The genome assembly and auxotrophic mutants developed are a key step to start using C. maltosa for comparative studies at a molecular level.