Sequencing Analysis of Cadmium and Arsenic Resistance Genes in a Listeria monocytogenes Strain Isolated from Meat
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Abstract:
In order to study the heavy metal resistance of food-borne Listeria monocytogenes and its resistance genes, an insertion sequence harboring a cadmium (Cd) resistance gene cassette, cadAC4, and an arsenic (As) resistance gene cassette, arsD1A1R1D2R2A2B1B2, from a single Listeria monocytogenes LM3 strain was identified in this experiment. The cadmium and arsenic resistance of the strain were measured by agar dilution method, and polymerase chain reaction (PCR), DNA analysis, and bioinformatics analysis were used to identify the structure of the insertion sequence and analyze the genetic islands harboring similar genes from different species. This strain exhibited a low level of cadmium resistance and was sensitive to arsenic. The strain harbored genes cadA4, arsA1, and arsA2, and did not harbor genes cadA1, cadA2, or cadA3. The cadmium resistance gene cadAC4 could mediate the low level of cadmium resistance, while the arsenic resistance gene cassette arsD1A1R1D2R2A2B1B2 was not expressed, or its expression was suppressed. The length of the sequence was 36629 bp, and it was highly conserved. This insertion sequence was identified for the first time in food-borne Listeria monocytogenes in an Asian country. The arsenic resistance gene cassette had a variety of locations and could be composed of different genes.
