Broad-spectrum antibacterial properties of a Pseudomonas field isolate and potential rhizomicrobiome implications

Plant growth promoting bacteria (PGPB) such as Pseudomonas have been widely acclaimed for their roles in sustainable food production and consumption of pollutants in contaminated soils. Yet, we still have much to learn about how dynamics of highly diverse microbial communities are influenced by PGPBs capable of antibacterial activity. This article characterizes the antimicrobial profile of an Indiana Pseudomonas field isolate. To our knowledge, this work is the first to demonstrate Pseudomonas-induced inhibition of the PGPB Serratia marcescens, as well as Pseudomonas-induced inhibition and/or color change of Kocuria rhizophila. These data raise intriguing questions about how best to maximize the efficacy of biofertilizers containing multiple different organisms while minimizing unintended disruption of soil microbiomes. In addition, similar to previously published Pseudomonas strains, our isolate inhibited growth of clinically relevant bacteria such as Staphylococcus, Mycobacterium, and Sarcina. Future studies thus should investigate whether Pseudomonas-derived antibiotics could have novel applications in treating opportunistic Serratia, Kocuria, or Sarcina human infections.