Methylotrophic yeasts like Hansenula polymorpha (recently known as Ogataea polymorpha) and Pichia pastoris are able to consume methanol as a sole carbon and energy source which makes them interesting microbial hosts for sustainable production of biomass and proteins. In a biorefinery concept, it is important to use the byproducts of other processes and combine them with microbial fermentation to make the whole process more sustainable and economical. For residual biomass streams like sewage sludge or wood remnants, steam gasification is a suitable process to produce syngas mixtures. During syngas cleaning, a water fraction containing nitrogen can be separated from a biodiesel scrubber. We developed a strategy to prepare a yeast fermentation media using this waste-stream ammonia from the gasification process. The growth of the yeasts was monitored for 50 hours and the cultures were analyzed in terms of viability, growth kinetics, and nitrogen consumption. It is observed that the growth rate (µ) of both yeasts growing on this waste-stream nitrogen source was comparable to the growth on a common synthetic medium having ammonium as a nitrogen source. This demonstrates that the ammonia recovered from gasification is a promising green nitrogen source for yeast fermentation.