Exogenous Protein as an Environmental Stimulus of Biofilm Formation in Select Bacterial Strains

Donna Ye,Maggie Lauria Sneideman,Kim Scribner,Mariane Mota Cavalcante,Jesse Kato,Lekha Bapu,Terence L Marsh,Thomas Loch

doi:10.4236/aim.2020.103011

Abstract

A screening of environmental conditions that would elicit robust biofilm in a collection of Serratia marcescens isolated from soil revealed that exogenous milk protein increased biofilm productivity up to ten-fold. A select screening of fish pathogens, freshwater and human isolates identified several other species that responded similarly to exogenous protein. The optimal protein concentration was species specific; S. marcescens at 5% milk protein, Aeromonas sp. at 2% - 3%, Flavobacterium columnare at 1% and Pseudomonas aeruginosa at 0.1% - 0.4%. Media supplemented with milk protein also increased the cell counts in biofilm as well as the protein incorporated into the biofilm matrix. These data suggest that relatively high concentrations of exogenous protein may serve as an environmental trigger for biofilm formation, particularly for pathogenic bacteria exposed to relatively high concentrations of protein in bodily fluids and mucosal surfaces.

Highlights

Since the concept of biofilm was first viewed through the eyes of molecular microbiology three decades ago, our appreciation of its importance in ecology has grown exponentially
During the screening of a variety of environmental conditions designed to stimulate the formation of biofilm by soil isolates of Serratia, we detected a significant increase in biofilm when our standard growth media, R2B, was supplemented with milk protein (MP)
Under all conditions we have tested, PA01 produced a robust biofilm when grown on R2B or TSB but had little response to the presence of exogenous protein when at 0.5% or greater and, in many of our assays, high concentrations of protein in the media slightly inhibited biofilm formation by P. aeruginosa

Summary

Introduction

Since the concept of biofilm was first viewed through the eyes of molecular microbiology three decades ago, our appreciation of its importance in ecology has grown exponentially. We recognize biofilm as an alternative life strategy for many, if not all species of microbes across three domains. Growth of a microbe in a biofilm removes it from a pelagic lifestyle that is characterized by mass action events (or close to it). Once attached to a surface and embedded in a macromolecular matrix, a very different lifestyle ensues one in which the tempo and mode of life are slowed, the ambient conditions change more gradually (in general) and cell physiology is altered [8]

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Discussion

Conclusion