Diversity of tetracycline-resistant bacteria and resistance gene tet(M) in fecal microbial community of Adélie penguin in Antarctica

Antibiotic-resistant bacteria can be detected in pristine environments and animals. Tetracycline (TC) is frequently used for wide areas of veterinary medicine, which selects TC-resistant bacteria. The TC resistance genes are known from natural environments, and tet(M) is the broadest host range tet gene. Here, we report that TC-resistant bacteria and the TC resistance gene tet(M) were diverse in Adélie penguin intestines, even within a single penguin colony. Total bacterial counts were as high as 10 CFU g, and TC-resistant bacteria ranged from 1.4 × 10 to 6.6 × 10 CFU g intestinal contents, which was 0–0.54 % of the total viable count. Phylogenetic affiliation of TC-resistant bacteria revealed a variety of Gram-positive and Gram-negative bacteria. The tet(M) gene was identified in 32.3 % of TC-resistant strains, and two tet(M) genotypes were identified within one penguin colony, suggesting various contamination origins of tet(M).