From the wound to the bench: exoproteome interplay between wound-colonizing Staphylococcus aureus strains and co-existing bacteria

ABSTRACT

Wound-colonizing microorganisms can form complex and dynamic polymicrobial communities where pathogens and commensals may co-exist, cooperate or compete with each other. The present study was aimed at identifying possible interactions between different bacteria isolated from the same chronic wound of a patient with the genetic blistering disease epidermolysis bullosa (EB). Specifically, this involved two different isolates of the human pathogen Staphylococcus aureus, and isolates of Bacillus thuringiensis and Klebsiella oxytoca. Particular focus was attributed to interactions of S. aureus with the two other species, because of the high staphylococcal prevalence among chronic wounds. Intriguingly, upon co-cultivation, none of the wound isolates inhibited each other's growth. Since the extracellular proteome of bacterial pathogens is a reservoir of virulence factors, the exoproteomes of the staphylococcal isolates in monoculture and co-culture with B. thuringiensis and K. oxytoca were characterized by Mass Spectrometry to explore the inherent relationships between these co-exisiting bacteria. This revealed a massive reduction in the number of staphylococcal exoproteins upon co-culturing with K. oxytoca or B. thuringiensis. Interestingly, this decrease was particularly evident for extracellular proteins with a predicted cytoplasmic localization, which were recently implicated in staphylococcal virulence and epidemiology. Furthermore, our exoproteome analysis uncovered potential cooperativity between the two different S. aureus isolates. Altogether, the observed exoproteome variations upon co-culturing are indicative of unprecedented adaptive mechanisms that set limits to the production of secreted staphylococcal virulence factors.

KEYWORDS:

• Staphylococcus aureus
• Bacillus thuringiensis
• Klebsiella oxytoca
• co-culture
• exoproteome
• chronic wound

This article is referred to by:

Polymicrobial infections: Do bacteria behave differently depending on their neighbours?

Disclosure of potential conflicts of interest

The authors declare that they have no financial and non-financial competing interests in relation to the documented research.

Acknowledgments

We thank Corinna Glasner, Andreas Otto, Tim Stobernack, Eleni Tsompanidou and Kai Zhou for helpful discussions.

Ethics

The present research has no particular ethical implications.

Additional information

Funding

This work was supported by the Graduate School of Medical Sciences of the University of Groningen, CoNaCyT, the Eleven Flowers Fund and the Ubbo Emmius Fund [to A.N.G.P. and J.M.v.D.], and by the Deutsche Forschungsgemeinschaft Grants GRK1870 and SFB/TRR 34 [to D.B.].