Investigation of a quorum sensing peptide in bacillus licheniformis and its novel antifungal property

Esmaeilishirazifard, E. 2016. Investigation of a quorum sensing peptide in bacillus licheniformis and its novel antifungal property. PhD thesis University of Westminster Life Sciences

TitleInvestigation of a quorum sensing peptide in bacillus licheniformis and its novel antifungal property
TypePhD thesis
AuthorsEsmaeilishirazifard, E.
Abstract

Quorum sensing molecules (QSMs) are involved in the regulation of complicated processes helping bacterial population benefit from their cell-density. This phenomenon has been recently studied in some fungal populations. Prokaryotes and Eukaryotes’ co-evolution raises the prospect of the existence of inter-kingdom signalling pathways. The involvement of hormone-like molecules such as QSMs in microbial cells communication promise potential role of QS process in inter-kingdom cross-talk.

Bacterial antagonistic activity against fungi is considered as an important bio-control opportunity to control fungal invasion of plants. Several bacterial species such as Bacillus spp. have shown the ability to inhibit fungal growth. During the screening of antagonistic bacteria against Aspergillus flavus (A. flavus), Bacillus subtilis (B. subtilis) was identified as having high antifungal activity. The bacterium, Bacillus licheniformis (B. licheniformis) is related to B. subtilis genetically and is used at industrial-scale for production of the antimicrobial compound bacitracin. Although the comQXPA cluster involved in QS development has been identified in the genome sequence of B. subtilis and different B. licheniformis strains, the QS system in B. licheniformis was not previously investigated in detail, and its QSM (ComX pheromone) was not identified.

In this context, and given the importance of this antagonistic bacterium as an industrial workhorse, this study was aimed to use B. licheniformis NCIMB-8874 as a model antagonistic bacterium to investigate its effect, and the effect of its ComX pheromone on potential inhibition of fungal growth.

The results obtained from bioinformatics studies on B. licheniformis NCIMB 8874 genome sequence presented in this project confirmed the presence of essential quorum sensing-related genes, such as the comQXPA gene cluster. The cell-cell communication of B. licheniformis NCIMB-8874 was investigated through further elucidation of QS process in this bacterium. The detection of the QSM, ComX pheromone, was achieved through molecular biology and biochemical studies including over-production, purification and partial identification.

Subsequently, the potential influence of ComX pheromone and Bacillus cells on the growth of A. flavus was examined and concluded that the QSM could cause a significant reduction in the growth of A. flavus strains (NRRL 3357 and ESP 15).

This work reports for the first time the amino acid sequence of the purified ComX pheromone and its novel antifungal property. Pheromone as a QSM is a potential signal for communication of cells between kingdoms and could be applied for bio-control purposes. Identification of new antifungal peptides against A. flavus could lead to the development of biotechnological strategies which facilitate control of aflatoxin contamination.

Year2016
FileEsmaeilishirazifard_Elham_thesis.pdf

Related outputs

A novel antifungal property for the Bacillus licheniformis ComX pheromone and its possible role in inter-kingdom cross-talk
Esmaeilishirazifard, E., Dariush, A., Moschos, S.A. and Keshavarz, T. 2018. A novel antifungal property for the Bacillus licheniformis ComX pheromone and its possible role in inter-kingdom cross-talk. Applied Microbiology and Biotechnology. 102 (12), pp. 5197-5208.

Genomic and molecular characterization of a novel quorum sensing molecule in Bacillus licheniformis
Esmaeilishirazifard, E., De Vizio, D., Moschos, S. and Keshavarz, T. 2017. Genomic and molecular characterization of a novel quorum sensing molecule in Bacillus licheniformis. AMB Express. 7, p. 78.

Investigation on quorum sensing molecule of Bacillus licheniformis and its antifungal property
Esmaeilishirazifard, E., Moschos, S.A. and Keshavarz, T. 2015. Investigation on quorum sensing molecule of Bacillus licheniformis and its antifungal property.

Bio‐control application of Bacillus quorum sensing on aflatoxigenic fungi through their inter‐kingdom cross‐talk
Esmaeilishirazifard, E., Moschos, S.A. and Keshavarz, T. 2015. Bio‐control application of Bacillus quorum sensing on aflatoxigenic fungi through their inter‐kingdom cross‐talk. 6th Congress of European Microbiologists (FEMS 2015). Maastricht, The Netherlands

Inter-kingdom cross-talk and its bio-control applications
Esmaeilishirazifard, E., Moschos, S.A. and Keshavarz, T. 2014. Inter-kingdom cross-talk and its bio-control applications. International Union of Microbiological Societies Congress. Montreal, Canada 31 Jul 2014

Bio-control applications of Bacillus quorum sensing on aflatoxigenic fungi
Esmaeilishirazifard, E., Moschos, S.A. and Keshavarz, T. 2014. Bio-control applications of Bacillus quorum sensing on aflatoxigenic fungi.

Aflatoxin occurrence
Esmaeilishirazifard, E. and Keshavarz, T. 2014. Aflatoxin occurrence. in: Faulkner, A.G. (ed.) Aflatoxins: food sources, occurrence and toxicological effects New York, USA Nova Science Publishers. pp. 35-62

Microbial metabolism of quorum-sensing molecules acyl-homoserine lactones, γ-heptalactone and other lactones
Safari, M., Amache, R., Esmaeilishirazifard, E. and Keshavarz, T. 2014. Microbial metabolism of quorum-sensing molecules acyl-homoserine lactones, γ-heptalactone and other lactones. Applied Microbiology and Biotechnology. 98 (8), pp. 3401-3412.

Interaction between Bacillus species and filamentous fungi for the control of fungal toxin production
Esmaeilishirazifard, E., Moschos, S.A. and Keshavarz, T. 2013. Interaction between Bacillus species and filamentous fungi for the control of fungal toxin production.

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