Recombinant production of a diamine oxidase in Komagataella phaffii and in vitro degradation of histamine in simulated intestinal fluid

Diamine oxidase (DAO-1) from Yarrowia lipolytica was recombinantly produced in Komagataella phaffii in fed-batch bioreactor cultivations using the constitutive GAP and methanol-inducible AOX1 promoters. Utilizing an exponential glucose feed, a maximum DAO-1 activity of 43 ± 7 µkat/L_culture was achieved after 37 h of cultivation using the GAP promoter. When the AOX1 promoter was used, a maximum DAO-1 activity of 230 ± 13 µkat/L_culture was achieved after 90 h of cultivation with a stepwise increase in the methanol feed. Thus, approximately 15- (GAP promoter) and 82-fold (AOX1 promoter) higher DAO-1 activities were obtained in K. phaffii compared to homologous recombinant production in Y. lipolytica. The DAO-1 produced in K. phaffii has been partially purified and was formulated as a sucrose-based tablet containing 4500 nkat DAO-1 activity. The DAO-1 tablet was tested for histamine degradation in a simulated intestinal fluid in the presence of food components, and approximately 90 % of the histamine applied initially (75 mg) was degraded in 90 minutes. This is the first time that a DAO-1 tablet has been able to break down such large amounts of histamine under simulated intestinal fluid conditions, which could help people with histamine intolerance in the future.