Efficient fermentative production of polymer-grade D-lactate by an engineered alkaliphilic Bacillus sp. strain under non-sterile conditions.

摘要: Polylactic acid (PLA) is one important chemical building block that well known as a biodegradable and biocompatible plastic. The traditional lactate fermentation processes need CaCO3 neutralizer to maintain the desired pH, which results in an amount of insoluble CaSO4 waste during purification process. To overcome such environmental issue, alkaliphilic organisms have great potential be used organic producer under NaOH-neutralizing agent based fermentation. Additionally, high optical purity property d-lactic now attracting more attention from both scientific industrial communities because it can improve mechanical properties PLA by blending l- or d-polymer together. However, use low-price nitrogen source for d-lactate combined with agent process has not been studied. Therefore, our goal was demonstrations newly simplify high-optical-purity production using low-priced peanut meal with non-sterile based In this study, we developed high-optical-purity an engineered Bacillus strain. First, native l-lactate dehydrogenase gene (ldh) knocked out, dehydrogenase Lactobacillus delbrueckii introduced to construct producer. key responsible exopolysaccharide biosynthesis (epsD) subsequently disrupted increase yield and downstream Finally, fed-batch under conditions conducted peanut nitrogen NaOH green neutralizer. titer reached 143.99 g/l, 96.09 %, overall productivity 1.674 g/l/h including highest at 16 h 3.04 g/l/h, even higher than that sterile fermentation. Moreover, purities (approximately 99.85 %) were obtained both conditions. Given cheap green process, study provides valuable favorable future polymer-grade production.