Download The production of lipopeptide biosurfactants by selected marine

RESEARCH GROUP: Pharmacy
Project Title: The production of lipopeptide biosurfactants by selected marine bacteria.
Supervisor(s):
Lead Supervisor (Chair): Prof Ibrahim Banat
Supervisor 2: Prof Roger Marchant
Contact Details: [email protected]
Level: PhD
Background to the project :Our group has an interest in the microbial production of biosurfactants and
their potential industrial or pharmacological applications (8). A major class of biosurfactants identified to be
produced by bacteria are the glycolipids, however a number of bacteria have been shown to produce
lipopeptides which have surface-active properties and can therefore be considered as biosurfactants (6). In
general, these Lipopeptides consist of a hydrophilic cyclic peptide conjugated to a hydrophobic fatty acid (9,
10). A specific example of a lipopeptide biosurfactant is Surfactin produced by Bacillus subtilis which
possesses the ability to reduce surface tension from 72 to 27.9 nMm-1 at very low concentrations (1).
Previous research has shown that a number of marine bacteria produce lipopeptide biosurfactants, however
research into the production of this class of biosurfactant by bacteria derived from the marine environment is
still considered as novel (2, 5 & 7). Previous research has indicated that lipopeptide biosurfactants possess
antimicrobial activity, it is therefore our belief that these molecules may have commercial applications in the
pharmaceutical sector and further research into their production by marine bacteria is justified (3, 4, 11 &
12).
Hypothesis: Marine bacteria possess the ability to produce lipopeptide biosurfactants that’s could have
scientific and commercial benefit.
Objectives of the research project :The first objective of this project is to ascertain lipopeptide production
in the bacterial species we have obtained as part of the Marisurf project and to determine the most effective
growth conditions for the production of the lipopeptide biosurfactants. The second objective is to develop
suitable extraction, purification and characterisation methods for the biosurfactants produced. The third
objective of this project is to examine the bioactivity of the biosurfactants as bacteriostatic and bactericidal
agents for application in the pharmaceutical industry. The final objective will be to describe potential
adjuvant effects of the lipopeptides in combination with established antibiotics used against common
nosocomial infection agents.
Methods to be used :The methods to be used in this project include microbial propagation in batch flask
and fermentation conditions, extraction and purification of microbial products using column
chromatography, solvent extraction and other purification methods. Characterisation of the lipopeptides and
their quantification will be performed using HPLC and GC-MS techniques. The purified lipopeptide will be
assessed for bacteriostatic and bactericidal effect using established microbiological techniques such as
antibiotic diffusion assays and e strip testing against both well characterised laboratory strains and patient
derived strains of various pathogenic bacteria. Adjuvant effect of these purified lipopeptides will be carried
out using similar antimicrobial activities in combination with other antibiotics. The purified lipopeptides will
be assessed for effects on cell cultures using cell culture based cytotoxicity assays.
Skills required of applicant :BSc (Hons) and/or MSc in biology, microbiology or a biomedical science
related area. Highly motivated, hardworking well organised individual who can work both independently
and as part of a research team. Experience in one or more of; basic microbiological techniques, tissue
culture, cell biology will be an advantage but training will be provided.
References :
1.
Arima, K., Kakinuma, A. & Tamura, G. (1963). Surfactin, a crystalline peptidelipid surfactant
produced by Bacillus subtilis: isolation, characterization and its inhibition of fibrin clot
formation. Biochemical & Biophysical Research Communications. 31 (3):488–494.
2.
Banat, I.M., Franzetti, A., Gandolfi, I. et al. (2010). Microbial biosurfactants production, applications
and future potential. Applied Microbial Biotechnology. 87 (2): 427-444.
3.
Balan, S.S., Kumar, C.G. & Jayalakshmi, S. (2017). Aneurinifactin, a new lipopeptide biosurfactant
produced by a marine Aneurinibacillus aneurinilyticus SBP-11 isolated from Gulf of Mannar:
Purification, characterization and its biological evaluation. Microbiological Research. 194 (1): 1-9.
4.
Campos, J.M., Montenegro, Stamford, T.L., Sarubbo, L.A., de Luna, J.M., Rufino, R.D. & Banat, I.M.
(2013) Microbial Biosurfactants as Additives for Food Industries: A review. Biotechnology Progress.
29: 1097-1108.
5.
Das, P., Mukherjee, S. & Sen, R. (2008), Antimicrobial potential of a lipopeptide biosurfactant derived
from a marine Bacillus circulans. Journal of Applied Microbiology. 104 (6): 1675–1684.
6.
Desai, J. D., & Banat, I. M. (1997). Microbial production of surfactants and their commercial
potential. Microbiology and Molecular Biology Reviews. 61 (1): 47–64.
7.
Kiran, G.S., Anto Thomas, T., Selvin, J., Sabarathnam, B. & Lipton, A.P. (2010). Optimization and
characterization of a new lipopeptide biosurfactant produced by marine Brevibacterium aureum
MSA13 in solid state culture. Bioresource Technology. 101 (7): 2389-2396.
8.
Marchant, R., & Banat, I. M. (2012). Microbial biosurfactants: challenges and opportunities for future
exploitation. Trends in Biotechnology. 30 (11): 558-565.
9.
Peypoux, F., Bonmatin, J.M. & Wallach, J. (1999). Recent trends in the biochemistry of
surfactin. Applied Microbiology Biotechnology. 51 (5):553–563.
10. Razafindralambo, H., Poineau, Y., Deleu, M., Hbid, C., Jacques, P., Thonart, P. & Paquot, M. (1998).
Foaming properties of lipopeptides produced by Bacillus subtilis: effect of lipid and peptide structural
attributes. Journal Agricultural Food Chemistry. 46 (3):911–916.
11. Rodrigues, L., Banat, I.M., Teixeira, J. & Oliveira, R. (2006). Biosurfactants: potential applications in
medicine. Journal of Antimicrobial Chemotherapy. 57, (4): 609-618.
12. Sing, P. & Cameotra, S.S. (2004). Potential applications of microbial surfactants in biomedical
sciences. Trends in Biotechnology. 22(3):142–146.