Rational development of bioprocess engineering strategies for recombinant protein production in Pichia pastoris (Komagataella phaffii) using the methanol-free GAP promoter. Where do we stand?

•Expanding use of Pichia pastoris for industrial recombinant protein production.•Bioprocess engineering advances reviewed in rational design of culture strategies.•Efficiency-enhanced rational novel cultivation strategies based on strain knowledge.•Methanol-free bioprocess alternatives for scalable Pichia fermentation in industry.•Key specific physiological rates define productivity, yields and product quality.