Construction and characterization of a promoter library with varying strengths to enhance acetoin production from xylose in Serratia marcescens

The objective of this study was to utilize a constitutive promoter screening strategy to enhance both xylose utilization and acetoin production inS. marcescens HBQA-7. By utilizing RNA-seq, we identified the endogenous constitutive promoter P6 that is the most robust, which facilitated the overexpression of the sugar transporter protein GlfL445I, α-acetyl lactate synthase, and α-acetyl lactate decarboxylase, respectively. The resultant recombinant strains exhibited enhanced xylose utilization rates and acetoin yields. Subsequently, a recombinant plasmid, denoted as pBBR1MCS-P6-glfL445IalsSalsD, was constructed, simultaneously expressing the aforementioned three genes. The resulting recombinant strain, designated as S3, demonstrated a 1.89-fold boost in xylose consumption rate compared with the original strain during shake flask fermentation. resulting in the accumulation of 7.14  g/L acetoin in the final fermentation medium. Subsequently, in a 5 L fermenter setup, the acetoin yield reached 48.75 g/L, corresponding to a xylose-to-acetoin conversion yield of 0.375 g/g.

Source: Biotechnology and Applied Biochemistry - January 16, 2024 Category: Biochemistry Authors: Jie Liu, Di Liu, Tingting Sun, Tai ‐Ping Fan, Yujie Cai Tags: ORIGINAL ARTICLE Source Type: research