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Can Mycobacteria help solve the global crisis of phosphorus bioavailability?

Primary Supervisor: Professor Galina Mukamolova, Department of Respiratory Sciences

Secondary supervisor: Dr Helen O’Hare

PhD project title: Can Mycobacteria help solve the global crisis of phosphorus bioavailability?

University of Registration: University of Leicester

Project outline:

Phosphorus is one of the planetary boundaries that determine Earth’s ecosystem stability and safe use of resources (1). Phosphorus is a key element of life required by all living organisms. Inorganic phosphate is widely used as fertiliser for improving soil quality and plant productivity. However, the excessive use of inorganic phosphate has damaging effects on the Earth ecosystems by polluting oceans, promoting accumulation of non-soluble forms of phosphorus in soil and eutrophication of water bodies. In this situation natural mineralisation and solubilisation of phosphorus by soil microorganisms becomes increasingly important.

Biomineralisation approach, is based on Microbial Induced Phosphate Precipitation (MIPP) technology, is a novel and one of the most interesting methods of soil remediation. In relies on application of microbial phosphatases for  improvement of  phosphorus bioavailability (2, 3).

Nutrient recycling, health and productivity of soil is entirely dependent on microorganisms. Actinobacteria are one of the most dominant phylotypes on Earth and important members of natural living communities. In particular, they produce multiple enzymes to break-down insoluble forms of phosphorus (such as phytates) (4). Therefore using Actinobacteria and their enzymes to access insoluble phosphorous could render damaged soil fertile again and/or reduce the need for soluble phosphorous fertilisers that destabilise natural cycles, thus providing an eco-friendly approach for Renewable Resources and Clean Growth.

Here we propose to investigate phosphatases produced by Mycobacteria (prominent members of Actinobacteria) and explore their possible application for degradation of insoluble phosphorus forms. Mycobacterium tuberculosis is the best characterised mycobacterium with a fully annotated genome and substantial characterisation of gene products (5). M. tuberculosis genome encodes several phosphatases, including Rv1692, Rv3113 and Rv3310, two phosphotyrosine and one phosphoserine/ threonine phosphatases and a predicted phytase Rv2577. Mycobacterium vaccae is an environmental soil inhabitant which could be used for improvement of soil quality. A bioinformatic analysis of M. vaccae genome and identification of phosphatases and phytases will be also done. Predicted phosphatases from M. tuberculosis and M. vaccaewill be produced in Escherichia coli and used to assess their ability to solubilise insoluble forms of phosphorus (e.g. phytate). M. vaccae strains over-producing various phosphatases will be generated and their phenotypes characterised.

References:

  1. Rockstrom et a A safe operating space for humanity. Nature. 2009. 461. 472–475.
  2. Jiang L et al. Ecotoxicol Environ Saf. 2020. 191:110009.
  3. Liang X., et al Appl Microbiol Biotechnol. 2016. 100(11):5141-51.
  4. Farias et al. New Bacterial Phytase through Metagenomic Prospection. Molecules. 2018. 23(2), 448;
  5. Kapopoulou et al. The MycoBrowser portal: a comprehensive and manually annotated resource for mycobacterial genomes. Tuberculosis (Edinb). 2018.91, 8-13.

BBSRC Strategic Research Priority: Renewable Resources and Clean Growth:Industrial Biotechnology

Techniques that will be undertaken during the project:

The project will involve the following methods:

  • Bioinformatic analysis
  • Generation of recombinant proteins and assessment of their activity
  • Genetic manipulation of mycobacteria, generation of deletion and over-expression mutants
  • Growth assays
  • Proteomics

Contact: Professor Galina Mukamolova, University of Leicester