Genomic and phenotypic characterization of Pseudomonas hygromyciniae, a novel bacterial species discovered from a commercially purchased antibiotic

A purchased lot of the antibiotic hygromycin B was found to be contaminated with a novel bacterial species, which we designate Pseudomonas hygromyciniae. Characteristics of P. hygromyciniae include its ability to use a variety of compounds as carbon sources, its pathogenicity towards lettuce and Galleria mellonella, and its ability to inhibit the growth of an E. coli strain. P. hygromyciniae is unlikely to be a human pathogen, as it did not survive at 37 {degrees}C and was not cytotoxic towards a mammalian cell line. The P. hygromyciniae strain harbors a novel 250 kb megaplasmid which confers resistance to hygromycin B and contains numerous other genes predicted to encode replication and conjugation machinery. These findings indicate that commercially manufactured antibiotics represent another extreme environment that may support the growth of novel bacterial species. IMPORTANCEMicrobial ecologists have surveyed numerous natural and manmade environments in search of new microbial species. In some instances, these microbes are discovered in harsh conditions, such as deep-sea vents, and their discovery leads to better understanding of how microbes adapt to their environment. Here, we have discovered a new species of bacteria from an extreme manmade environment: a lyophilized, commercially available bottle of the antibiotic hygromycin B.