Ascospores are formed by which yeast isolate?

Ascospores are a type of reproductive spore formed through the process of ascosporogenesis, which occurs in certain fungi, particularly those belonging to the Ascomycete group. Saccharomyces cerevisiae, commonly known as baker's yeast, is one of the most well-known yeasts that produce ascospores. During its sexual reproduction phase, it can form ascospores within a sac called an ascus.

In contrast, Candida albicans does not typically reproduce by forming ascospores; it primarily reproduces asexually through budding. Cryptococcus neoformans, while it does have a complex life cycle and can produce spores, forms a different kind of reproductive structure, primarily large encapsulated yeast cells rather than ascospores.

Therefore, the most accurate answer to the question regarding which yeast isolate forms ascospores is Saccharomyces cerevisiae, as it specifically undergoes the process of ascosporogenesis.