Research

 

III. Microbial Surfactants (Biosurfactants)

 

 

Research in the area of microbial biosurfactants focuses on the discovery of new biosurfactants, elucidation of the role of biosurfactants in microbial survival, and the development of potential biomedical and environmental applications for these fascinating molecules. Our current work focuses on two biosurfactants; (1) rhamnolipid biosurfactant produced by Psuedomonas aeruginosa and (2) the siderolipid biosurfactant (flavolipid). Siderolipids were discovered by our lab and are produced by a Flavobacterium spp. isolated from a soil sample taken from Mt. Lemmon in the Santa Catalina Mountains north of Tucson. 

Ph.D. Student, Lin Zhang, working in the laboratory

with the rotoevaporator. She is studying the structure of rhamnolipids produced by Pseudomonas aeruginosa using different carbon sources.

 

 

Rhamnolipid:
As part of a NSF Collaborative Research in Chemistry grant project we are investigating the effect of carbon substrate on the different rhamnolipid congeners produced by various strains of P. aeruginosa. The two major rhamnolipid structures are monorhamnolipid and dirhamnolipid
.

We have shown that a natural mutant, P. aeuruginosa ATCC 9027 which produces only monorhamnolipids, makes up to 29 different chemical variations of this molecule and the distribution of these structures changes with carbon supply. This research provides exciting possibilities for potential biotechnology applications because each of these congeners has slightly different physico-chemical properties

We are also examining the effect of carbon source on yields of rhamnolipid produced. Microarray and real-time PCR analysis are providing information on the biosynthetic control of rhamnolipid synthesis and has resulted in the ability to design media that results in 50-fold increases (or greater) in yield.

  (to the left) A batch culture of Pseudomonas aeruginosa. The froth on the top of the culture indicates good rhamnolipid production.
   

Lab Manager and Research Specialist, Julie Neilson,
shows pure rhamnolipid biosurfactant.

 

Siderolipid (flavolipid):

Siderolipids represent a new class of biosurfactants with strong surface activity and emulsifying ability. The polar moiety of siderolipids feature citric acid and two cadaverine molecules, which is quite different from the polar moieties found in any of the currently reported classes of biosurfactants. This new biosurfactant will be of interest for potential use in a wide variety of industrial and biotechnology applications. Current research is directed at identifying the genes responsible for siderolipid production by Flavobacterium sp. In addition, work is being pursued to develop a growth media that can increase the yield of this biosurfactant.

   
 

Structure of flavolipid isolated from Flavobacterium sp.
strain MTN11.

Project: Collaborative Research in Chemistry: Fundamental Surface and Interfacial Chemistry of Microbially-Produced Biosurfactants 

Funding Source: NSF Collaborative Research in Chemistry

Collaborators: Dr. Jeanne E. Pemberton, Dr. Robin L. Polt and Dr. Maria Teresa Velez

Relevant Publications:

Zhang, L., T.A. Veres-Schalnat, A. Somogyi, J.E. Pemberton, and R.M. Maier.  2012. Fatty acid β-oxidation provides precursors for rhamnolipid biosynthesis in Pseudomonas aeruginosa: evidence from isotope tracing and gene expression. Appl. Environ. Microbiol., in revision.

Ange, A.L., R.B. Bates, B.L. Bell, A.A. Bodour, B.R. Bourne, C.G. Contreras, E.L. Goldberg, A.A.L. Gunatilaka, S. King, A.K. Lee, R.L. Low, R.M. Maier, K.M. Marlor, M.T. Marron, R.C. Scolnik, M.J. Streeter, M. Strelczuk, L.N. Trinh, V.K. Truong, S.P. Vissering, M.C. Weick, M.T. Williams. 2010.  Synthesis and biological activities of flavolipids. Tetrahedron, 66:9107-9112.

 

Neilson, J.W., L. Zhang, T.A. Veres, K.B. Chandler, C.H. Neilson, J.D. Crispin, J.E. Pemberton, and R.M. Maier. 2010.  Heavy metal effects on transcriptional expression of rhlB/rhlC genes and dirhamnolipid/monorhamnolipid ratios. Appl. Microbiol. Biotechnol., 88:953-963.

 

Saini, H.S, B.E. Barragán-Huerta, A. Lebrón-Paler, J.E. Pemberton, R.R. Vázquez, A.M. Burns, M.T. Marron, C.J. Seliga, A.A.L. Gunatilaka, and R.M. Maier. 2008.  Efficient purification of the biosurfactant viscosin from Pseudomonas libanensis strain M9-3, and its physicochemical and biological properties.  J. Nat. Prod.  71:1011-1015. PMID: 18471020

Ochoa-Loza, F.J., W.H. Noordman, D.B. Jannsen, M.L. Brusseau, and R.M. Maier.  2007.  Effect of clays, metal oxides, and organic matter on rhamnolipid biosurfactant sorption by soil.  Chemosphere, 66:1634-1642. PMID: 16965801  

Lebron-Paler, A., J.E. Pemberton, W.C. Otto, B.K. Becker, C.K. Larive and R.M. Maier. 2006.  Determination of the acid dissociation constant of the biosurfactants monorhamnolipid in aqueous solution by potentiometric and spectroscopic methods.  Anal. Chem. 78:7649-7658.  PMID: 17105155

Bodour, A.A., C. Guerrero-Barajas, B.V. Jiorle, M.E. Malcomson, A.K. Paull, A. Somogyi, L.N. Trinh, R.B. Bates, and R.M. Maier.  2004.  Structure and characterization of flavolipids, a novel group of biosurfactants produced by Flavobacterium sp. MTN11.  Appl. Environ. Microbiol. 70:114-120.  PMID: 14711632

Maier, R.M.  2003.  Biosurfactants: evolution and diversity.  Adv. Appl. Microbiol.  52: 101-121.  PMID: 12964241

Bodour, A.A., K.P. Drees, and R.M. Maier.  2003.  Distribution of biosurfactant-producing microorganisms in undisturbed and contaminated arid southwestern soils.  Appl. Environ. Microbiol.  69:3280-3287.  PMID: 12788727

Ochoa-Loza, F.J., J.F. Artiola, and R.M. Maier.  2001.  Stability constants for the complexation of various metals with a rhamnolipid biosurfactant.  J. Env. Qual.  30:479-485.

Maier, R.M. and G. Soberon-Chavez.  2000.  Pseudomonas aeruginosa rhamnolipids: biosynthesis and potential environmental applications.  Appl. Microbiol. Biotechnol.  54:625-633.
Al-Tahhan, R. T.R. Sandrin, A.A. Bodour, and R.M. Maier.  2000.  Rhamnolipid-induced removal of lipopolysaccharide from Pseudomonas aeruginosa: effect on cell surface properties and interaction with hydrophobic substrates.  Appl. Environ. Microbiol. 66:3262-3268.