Ability to assimilate nitrogenous oxides is limited to a few species of yeasts.

Several species of yeasts, Saccharomyces cerevisiae, Debaryomyces hansenii, Candida utilis, C. albicans, C. pelliculosa and C. tropicalis, were tested for their ability to utilise different inorganic nitrogen compounds as sole sources of nitrogen, and the results are presented as a function of their growth. All of them grew well on reduced nitrogenous compounds such as ammonium sulphate (ammonia) and L-asparagine, while only C. utilis and C. pelliculosa grew, at a slower rate, on oxidised nitrogenous compounds, nitrate and nitrite. The differences observed in the ability of various yeasts to assimilate the inorganic nitrogen compounds are believed to reflect their individuals abilities to regulate the uptake rates of potentially toxic compounds and keep them in a bound/transient state until reduced to less toxic and more-readily assimilable forms.