Laccase-producing gut bacteria from the larvae of Acrobasis nuxvorella (Lepidoptera: Pyralidae)

Acrobasis nuxvorella Neuzing (Lepidoptera: Pyralidae) is a monophagous pest of Carya illinoinensis (Wangenh) K. Koch, a plant rich in tannins. When the tannins degrade, high concentrations of gallic acid are released, which are harmful to some insects. However, Acrobasis nuxvorella larvae are not affected by feeding on the plant when gallic acid is released. Therefore, it may be expected that Acrobasis nuxvorella larval gut microbiota may produce the enzyme laccase, enabling them to biotransform gallic acid into other useful molecules. Thus, the intestinal content of the insect was recovered. Among 175 bacterial isolates, 8 showed laccase activity in the range of 0.52–3.9 U/µg of protein. The isolates with laccase activity were identified as the Bacillus species: Bacillus pumilus, Bacillus safensis, Bacillus altitudinis, and Bacillus xiamenensis through 16S ribosomal RNA gene sequencing. In addition, the cotA gene coding for the laccase enzyme was found in the genomic DNA of these eight Bacillus isolates.