Identification and Characterization of als Genes Involved in D-Allose Metabolism in Lineage II Strain of Listeria monocytogenes .

Listeria monocytogenes , an important food-borne pathogen, causes listeriosis and is widely distributed in many different environments. In a previous study, we developed a novel enrichment broth containing D-allose that allows better isolation of L. monocytogenes from samples. However, the mechanism of D-allose utilization by L. monocytogenes remains unclear. In the present study, we determined the metabolism of D-allose in L. monocytogenes and found that lineage II strains of L. monocytogenes can utilize D-allose as the sole carbon source for growth, but lineage I and III strains cannot. Transcriptome analysis and sequence alignment identified six genes ( lmo0734 to 0739 ) possibly related to D-allose metabolism that are only present in the genomes of lineage II strains. Recombinant strain ICDC-LM188 containing these genes showed utilization of D-allose by growth assays and Biolog phenotype microarrays. Moreover, lmo0734 to 0736 were verified to be essential for D-allose metabolism, lmo0737 and 0738 affected the growth rate of L. monocytogenes in D-allose medium, while lmo0739 was dispensable in the metabolism of D-allose in L. monocytogenes . This is the first study to identify the genes related to D-allose metabolism in L. monocytogenes , and their distribution in lineage II strains. Our study preliminarily determined the effects of these genes on the growth of L. monocytogenes , which will benefit the isolation and epidemiological research of L. monocytogenes .