Catabolite responsive element deficiency of xyl operon resulting in carbon catabolite derepression in Lactobacillus fermentum 1001.
OBJECTIVE
To explore the molecular mechanism of the carbon catabolite derepression in Lactobacillus fermentum 1001 when this strain consumed xylose and glucose simultaneously.


RESULTS
The transcriptional level of ccpAf was measured by real-time qPCR, revealing that ccpAf transcribed mRNA normally in Lact. fermentum 1001. The ccpAf gene could complement the ccpA-deficiency of a Lactococcus lactis mutant. Moreover, when the phosphofructokinase from Lactobacillus delbrueckii subsp. bulgaricus ATCC 11842 was expressed in Lact. fermentum 1001, the recombinant preferred glucose to fructose rather than to xylose. All data suggested that CcpAf was functional in Lact. fermentum 1001. In addition, the promoter (Plx) activity of the xyl operon from Lact. fermentum 1001 was further test in Lactobacillus casei BL23, and it could drive the expression of green fluorescent protein in the presence of glucose.


CONCLUSIONS
The ability of Lact. fermentum 1001 to co-utilize xylose and glucose resulted from the deficiency of catabolite responsive element in P1x rather than the null mutation of the ccpAf gene.


CONCLUSIONS
Lactobacillus fermentum 1001 is a potential candidate as a CCR-absent cell factory to transform biomass to high-value-added products. P1x was provided for engineering LAB to enhance fermentation efficiency by avoiding CCR.
State Key Laboratory of Microbial Technology, Shandong University, Jinan, China.
C
C
Zhang
State Key Laboratory of Microbial Technology, Shandong University, Jinan, China.
T
T
Guo
State Key Laboratory of Microbial Technology, Shandong University, Jinan, China.
Y
Y
Xin
State Key Laboratory of Microbial Technology, Shandong University, Jinan, China.
X
X
Gao
State Key Laboratory of Microbial Technology, Shandong University, Jinan, China.
J
J
Kong
D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D002244:Carbon / Q000378:metabolism*; D005285:Fermentation; D015964:Gene Expression Regulation, Bacterial; D005947:Glucose / Q000378:metabolism; D052197:Limosilactobacillus fermentum / Q000235:genetics / Q000378:metabolism*; D009876:Operon; D011401:Promoter Regions, Genetic; D014994:Xylose / Q000378:metabolism*
D001426:Bacterial Proteins; D002244:Carbon; D014994:Xylose; D005947:Glucose
Lactobacillus fermentum; carbon catabolite derepression; catabolite responsive element; ccpAf; phosphofructokinase; xylose utilization