Economic process to co-produce poly(ε-l-lysine) and poly(l-diaminopropionic acid) by a pH and dissolved oxygen control strategy

This study tended to apply biorefinery of indigenous microbes to the fermentation of target-product generation through a novel control strategy. A novel strategy for co-producing two valuable homopoly(amino acid)s, poly(ε-l-lysine) (ε-PL) and poly(l-diaminopropionic acid) (PDAP), was developed by controlling pH and dissolved oxygen concentrations in Streptomyces albulus PD-1 fermentation. The production of ε-PL and PDAP got 29.4 and 9.6 g L−1, respectively, via fed-batch cultivation in a 5 L bioreactor. What is more, the highest production yield (21.8%) of similar production systems was achieved by using this novel strategy. To consider the economic-feasibility, large-scale production in a 1 t fermentor was also implemented, which would increase the gross profit of 54,243.5 USD from one fed-batch bioprocess. This type of fermentation, which produces multiple commercial products from a unified process is attractive, because it will improve the utilization rate of raw materials, enhance production value and enrich product variety.