Microbial competition between Bacillus subtilis and Staphylococcus aureus monitored by imaging mass spectrometry

Abstract

Microbial competition exists in the general environment, such as soil or aquatic habitats, upon or within unicellular or multicellular eukaryotic life forms. The molecular actions that govern microbial competition, leading to niche establishment and microbial monopolization, remain undetermined. The emerging technology of imaging mass spectrometry (IMS) enabled the observation that there is directionality in the metabolic output of the organism Bacillus subtilis when co-cultured with Staphylococcus aureus. The directionally released antibiotic alters S. aureus virulence factor production and colonization. Therefore, IMS provides insight into the largely hidden nature of competitive microbial encounters and niche establishment, and provides a paradigm for future antibiotic discovery.

Primer on Agar-Based Microbial Imaging Mass Spectrometry

“…Microbial IMS sample preparation workflow (Fig. 2) begins with culturing one or more microbes on agar-based medium directly on top of the MALDI target plate (70) or in petri dishes (18,34). The agar is 1 to 1.5 mm thick, equivalent to 10 to 11 ml medium in a standard 10-cm petri dish, and typically contains 1 to 2% agar.…”

“…Traditionally, individual microbial metabolites have been targeted using bioactivityguided fractionation. More recent "omics" technologies, such as metabolomics, begin to capture molecules on a global scale, but current mass spectrometry-based approaches do not distinguish between molecules which are always present and molecules with changing spatial distributions, disregarding the spatial localization of the molecules within a phenotype and the multifaceted chemical exchange within and between microbial cell populations (18,19,60).…”

Utilizing a Robotic Sprayer for High Lateral and Mass Resolution MALDI FT-ICR MSI of Microbial Cultures

“…V isualizing microbial interactions with mass spectrometry imaging (MSI) has provided insights into many important biological processes, where it has captured molecular snapshots of metabolic exchange, antibiotic resistance, microbial competition, and more [1][2][3][4][5][6][7]. There are a number of different MSI methods reported for chemical mapping of microbial systems [3,4,6].…”

“…We utilize the well-characterized model system of wild type Bacillus subtilis to demonstrate the benefits of this sample preparation method [2,6]. This robotic sprayer offers two-dimensional control of matrix application, providing an even more uniform matrix surface coverage and sublimation-like crystal sizes [11].…”

Reduction of the Microbiological Load on Hospital Surfaces Through Probiotic-Based Cleaning Procedures: A New Strategy to Control Nosocomial Infections

“…Among these, one of the most representative is surfactin, produced by Bacillus subtilis, which is a surface-active lipopeptide belonging to the extracellular polymeric substances (EPS) [39] displaying a potent antimicrobial activity [40]. In addition, other competition-related processes such as cannibalism and predation are involved in the formation of the biofilm and in the antimicrobial activity of Bacillus subtilis, respectively [41][42][43][44].…”