Abstract

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The growing crisis of infections due to antibiotic-resistant organisms poses a huge threat to human health, and creates a need for antibiotic discovery.  The lichens, bryophytes, and pteridophytes hold promise as potential sources for new antimicrobial compounds, and represent an opportunity for discovery of novel chemical structures.  This project will focus on collecting lichen, bryophyte, and pteridophyte specimens in northwest Montana, with the aim of collecting specimens and preparing extracts to test for antibiotic activity in disk-diffusion assays.

Widespread overuse of antibiotics in the medical and agricultural communities has resulted in extensive antibiotic resistance at the global level and poses an immense threat to human heath (R. Laxminarayan et al., 2013). The most commonly used antibiotics are synthesized from fungi & bacteria, yet other organisms such as lichen (G. Shestha, 2014), bryophytes (mosses & liverworts), (R. Mishra et al., 2014) and pteridophytes (ferns and fern-allies) (Morais-Braga et al., 2012, A. Mandal et al., 2011) have sparked scientific interest because of their promise in yielding antimicrobial compounds; yet only a small fraction of species have been scientifically tested – less than 5% of bryophyte species worldwide have been tested for antibiotic activity (Nikolajeva et al., 2012). The overarching goal of our research with undergraduate students is to determine whether locally occurring lichens and plants, primarily bryophytes and pteridophytes, have the potential to be utilized as antibiotics against various pathogenic bacteria. We have chosen to focus specifically on these groups of plants because they contain abundant secondary metabolites – lichen alone contains more than 1000 different identified compounds (G. Shestha, 2014).

Significance

The crisis of antimicrobial resistance adds an enormous burden to the cost of health care in the United States.  In 2013, the Centers for Disease Control and Prevention estimated that treating infections due to antibiotic-resistant organisms added over 20 billion dollars to direct healthcare costs and an additional 35 billion dollars in lost productivity (CDC, 2013).  Discovery of new antibiotic compounds has slowed such that in the years 2003 – 2007, only 5 new antimicrobial agents were approved for clinical use (Moellering, 2011). Growing concern has led to increased research focus in academic laboratories and in both biotech and pharmaceutical research companies, so that the number of compounds in the FDA approval pipeline is increasing (Bush, 2011) and new approaches to antimicrobial discovery using genomic and transcriptomic analyses are being devised (Brown and Wright, 2016, Jones, et al., 2016). 

In addition to the genomic approaches to antibiotic discovery, attention has refocused on “mining” for new antimicrobial molecules from traditional medicine sources. Given the tremendous need for these new compounds, and the potential for discovery among the plant, lichen, and fungal group, we have focused our attention on collection and testing of specimens from Northwest Montana. This approach uses traditional methods of extraction and in vitro culture testing, and provides a straightforward method that can potentially yield compounds for further study.

Specific Aims

  1. Collect, identify, and preserve lichen, bryophyte, and pteridophyte species present in northwest Montana
  2. Measure the antibiotic potential of lichen, bryophytes and pteridophyte species against representative Gram positive and Gram negative bacteria in disc-diffusion assays
  3. Determine the optimal solvent (i.e. ethanol, methanol, acetone, etc.) for obtaining antibiotic extracts
  4. Determine the minimal inhibitory concentration (MIC) of antibiotic extracts using broth cultures.
  5. Determine whether extracts have cytotoxic effects on mammalian culture cells
  6. Provide an opportunity for undergraduate students to gain practical field and laboratory skills that they, otherwise, would not be exposed to in a typical classroom setting

Primary Contact

Ruth Wrightsman rwrightsman@fvcc.edu