Department of Biology

Robert McLean

Professor
 

Phone: 512-245-3365

Fax: 512-245-8713

E-mail: McLean@txstate.edu

[ Mailing Address / Research Interests / Courses Taught / Publications / Theses Directed / Students & Postdocs ]

Mailing Address

Department of Biology
Texas State University
601 University Drive
San Marcos , TX 78666
 
 

Education

B. Sc. Microbiology, University of Guelph , 1978
Ph.D. Microbiology, with JW Costerton , University of Calgary , 1986
Postdoc with TJ Beveridge, University of Guelph , 1986 - 1988
Developmental Leave:

W ith Debby Siegele , Department of Biology, Texas A&M University , Fall 2000

With Marvin Whiteley, Molecular Genetics & Microbiology, University of Texas, Spring 2008
 

Memberships in Scientific Societies

American Society for Microbiology
Texas Branch, American Society for Microbiology (Region Planning Coordinator for ASM region 6 (2007-2009), covering Missouri Valley, Rio Grande, Rocky Mountain, and Texas ASM branches)

Asociación Mexicana de Microbiología, AC

Canadian Society of Microbiologists
International Society for Microbial Ecology

Sigma Xi Scientific Research Society
 

Research Interests

Biofilms: Most bacteria in their natural environments live on surfaces as slime-encased, biofilm communities. In contrast to their planktonic counterparts, sessile bacterial populations are significantly more resistant (by several orders of magnitude) to environmental stresses such as harmful chemicals, antibiotics and predation. While biofilms are the dominant form of growth of bacteria in nature, little is known about the biological factors that allow growth as biofilms. Studies in my lab, done in collaboration with Debby Siegele ,  Clay Fuqua , Walt Fast, Dhiraj Vattem, and Sandy Pierson , address three major aspects of bacterial physiology which are important in biofilm growth and development. These include the ability of individual bacteria to grow slowly, survive starvation stresses, express a variety of biofilm-activated genes, and for the organisms within a biofilm community to perform many metabolic activities as a group through a phenomenon known as quorum-sensing. Recently in collaboration with Marvin Whiteley, we have expanded these studies by employing gene arrays and transcriptional profiling to investigate overall patterns of gene expression in mixed culture bacterial biofilms. 

Bacteria in nature, including those within biofilms, live as mixed populations. Therefore in order to understand natural biofilm growth, it is important to investigate microbial interactions in mixed communities. We have observed that bacterial community composition affects biofilm formation and susceptibility to iodine disinfection ( link to abstract ), and are now investigating whether quorum-sensing and other physiological activities affect biofilm community structure.

Aside from their importance on earth, biofilms may also impact the success of Payload patch for shuttle flight STS-95future long-term space flights due to possible fouling of water recycling filters. We recently flew an experiment in the John Glenn space shuttle (STS-95 ) to show that the bacterium, Pseudomonas aeruginosa, could form biofilms under weightless conditions ( link to abstract ).  In a follow-up experiment, we flew an Columbia picture showing payload behind astronaut Kalpana Chawlaexperiment on shuttle flight STS-107 , which STS-107 Mission Patchlaunched on January 16, 2003 to study biofilm formation and microbial competition in a three-member bacterial consortium. On February 1 2003 , during reentry, the space shuttle Columbia was destroyed along with all crew members . These include Commander Rick Husband, Pilot William McCool, Payload Commander Michael Anderson, Mission Specialist David Brown, Mission Specialist Kalpana Chawla, Mission Specialist Laurel Clark, and Payload Specialist Ilan Ramon. We mourn the loss of these seven outstanding people and offer our thoughts and prayers for their families and friends.    Appended is a photograph taken aboard Columbia during STS-107, showing Astronaut Kalpana Chawla with our payload visible in the upper left corner. Amazingly, our payload survived the impact and we gained access to it during the week of May 5, 2003. Some images can be seen at http://mediaarchive.ksc.nasa.gov/detail.cfm?mediaid=19550 , http://mediaarchive.ksc.nasa.gov/detail.cfm?mediaid=19539 , http://mediaarchive.ksc.nasa.gov/detail.cfm?mediaid=19475 . We have found one organism in the payload that may have survived this disaster (McLean et al., Icarus 181: 323-325, 2006) (link to abstract). 

 

Microbial Mineral formation and nanobacteria: Bacteria and other microorganisms have been associated with the formation of many types of sedimentary rocks and minerals. Recently, small bacteria-shaped objects have been described by RL Folk, a geologist at the University of Texas . While these objects resemble bacteria, they are approximately 1/5 the size and have thus been termed nanobacteria (also spelled nannobacteria). Although initially thought to be independant life forms, our current thinking is that they are more likely to represent remnants of bacterial polymers (slime) and possibly outer membrane vesicles. Aside from their potential importance in geology, they have also been cited as evidence of extraterrestrial life on a recently described Martian meteorite. Nanobacteria research in my lab, in association with Robert L Folk (Geological Sciences , University of Texas ), Brenda L Kirkland and F Leo Lynch , (Geosciences , Mississippi State University ) seeks to ascertain the nature of nanobacteria and to investigate whether they are involved in mineral formation.

Courses Taught

BIO 2400: Microbiology

BIO 4445/5445: Pathogenic Microbiology

 

BIO 4447/7447: Microbial Physiology and Genetics

Internet Search Sites for Research Articles:

  • Entrez PubMed for Medically Relevant Journal Articles
  • Agricola for Agricultural and Environmentally Relevant Journal Articles
  • Online Analysis Site , good starting point and resource for analytical tools for nucleic acid and protein analysis


Microbiology Web Links

Other Links:

Publications

SELECTED PAPERS (1990 - present)

  • McLean, RJC, D Beauchemin, L. Clapham, and TJ Beveridge. 1990. Metal binding characteristics of the gamma glutamyl capsule polymer of Bacillus licheniformis ATCC 9945. Applied and Environmental Microbiology 56: 3671 - 3677.
  • McLean, RJC, J. Downey, L. Clapham, and JC Nickel. 1990. Influence of chondroitin sulfate, heparin sulfate, and citrate on Proteus mirabilis induced struvite crystallization in vitro. Journal of Urology 144: 1267 - 1271.
  • McLean, RJC, J. Downey, L Clapham, and JC Nickel. 1990. A simple technique for studying struvite crystal growth in vitro. Urological Research 18: 39 - 43.
  • Clapham, L., RJC McLean, JC Nickel, J. Downey, and JW Costerton. 1990. The influence of bacteria on struvite crystal habit and its importance in urinary stone formation. Journal of Crystal Growth 104: 475 - 484.
  • McLean, RJC, JR Lawrence, DR Korber, and DE Caldwell. 1991. Proteus mirabilis biofilm protection against struvite crystal dissolution and its implications in struvite urolithiasis. Journal of Urology 146:1138 - 1142.
  • Beynon, LM, AJ Dumanski, RJC McLean, LL MacLean, JC Richards, and MB Perry. 1992. Capsule structure of Proteus mirabilis (ATCC 49565). Journal of Bacteriology 174: 2172 - 2177.
  • McLean, RJC, D Beauchemin, and TJ Beveridge. 1992. Influence of oxidation state on iron binding by Bacillus licheniformis capsule. Applied and Environmental Microbiology 58: 405 - 408.
  • McLean, RJC, AA Hussain, M Sayer, PJ Vincent, DJ Hughes, and TJN Smith. 1993. Antibacterial activity of multilayer silver-copper surface films on catheter material. Canadian Journal of Microbiology 39: 895 - 899.
  • Dumanski, AJ, H Hedelin, A Edin-Liljegren, D Beauchemin, and RJC McLean. 1994. Unique ability of Proteus mirabilis capsule to enhance mineral growth in urinary calculi. Infection and Immunity 62: 2998 - 3003.
  • McLean, RJC, AM Campbell, PT Khu, AT Persaud, LE Bickerton, and D Beauchemin. 1994. Repeated use of Bacillus subtilis cell walls for copper binding. World Journal of Microbiology and Biotechnology 10: 472 - 474.
  • Hussain, AA, M Sayer, RJC McLean, DJ Hughes, and TJN Smith. 1994. Surface texturing of multilayer Ag-Cu films by sputter etching. Vacuum 45: 121 - 125.
  • Stickler, DJ and RJC McLean. 1995. Biomaterials associated infections: the scale of the problem. Cells and Materials 5: 167 - 182.
  • Tolson, DL, DL Barrigar, RJC McLean, and E Altman. 1995. Expression of a non-agglutinating fimbria by Proteus mirabilis. Infection and Immunity 63: 1127 - 1129.
  • McLean, RJC, DJ Stickler, and JC Nickel. 1996. Biofilm mediated calculus formation in the urinary tract. Cells and Materials 6: 165-174.
  • McLean, RJC, D Fortin, and DA Brown. 1996. Microbial metal binding mechanisms and their relation to nuclear waste disposal. Canadian Journal of Microbiology 42: 392 - 400.
  • Dunn, KA, RJC McLean, GR Upchurch, Jr., and RL Folk. 1997. Enhancement of leaf fossilization potential by bacterial biofilms, Geology 25: 1119-1122.
  • McLean, RJC, M Whiteley, DJ Stickler, and WC Fuqua. 1997. Evidence of autoinducer activity in naturally-occurring biofilms. FEMS Microbiology Letters 154: 259-263.
  • Whiteley, M, E Brown, and RJC McLean. 1997. An inexpensive chemostat apparatus for the study of microbial biofilms. Journal of Microbiological Methods 30: 125-132.
  • McLean, RJC, HE Jamieson, and DR Cullimore. 1997. Formation of nesquehonite and other minerals in vitro as a consequence of biofilm dehydration. World Journal of Microbiology and Biotechnology 13: 25-28.
  • Stickler, DJ, NS Morris, RJC McLean, and C Fuqua. 1998. Biofilms on indwelling urinary catheters produce quorum-sensing signal molecules in situ and in vitro. Applied and Environmental Microbiology 64: 3486–3490.
  • Koenig, MK and RJC McLean. 1999. Influence of metal ions, temperature, and polymer concentration on the conformation of Escherichia coli K1 capsular polysaccharide. BioMetals 12: 47-52.
  • Kirkland, BL, FL Lynch, MA Rahnis, RL Folk, IJ Molineux, and RJC McLean. 1999. Alternative origins for nannobacteria-like objects in calcite. Geology 27: 347-350.
  • McLean, RJC, M Whiteley, BC Hoskins, PD Majors, and MM Sharma. 1999. Laboratory techniques for studying biofilm growth, physiology, and gene expression in flowing systems and porous media. Methods in Enzymology 310: 248–264.
  • McLean, RJC 1999. Original research projects as a major component of an undergraduate microbiology course. Journal of College Science Teaching 29: 38-40.
  • Adams, JL and RJC McLean. 1999. The impact of rpoS deletion on Escherichia coli biofilms. Applied and Environmental Microbiology 65: 4285-4287.
  • Prabhakaran, S, JMH Teichman, SS Spore, E Sabanegh , RD Glickman, and RJC McLean. 1999. Proteus mirabilis viability after lithotripsy of struvite calculi. Journal of Urology 162: 1666-1669.
  • Morris, NS, D Stickler, and RJC McLean. 1999. The development of bacterial biofilms on indwelling urethral catheters. World Journal of Urology 17: 345-350.
  • McLean, RJC, BD Corbin, GJ Balzer, and GM Aron. 2001. Phenotype characterization of genetically defined microorganisms and growth of bacteriophage in biofilms. Methods in Enzymology 336: 163-174.
  • Whiteley, M, JR Ott, EA Weaver, and RJC McLean . 2001. Effects of community composition and growth rate on aquifer biofilm bacteria and their susceptibility to betadine disinfection. Environmental Microbiology 3: 43-52.
  • McLean, RJC, JM Cassanto, MB Barnes, and JH Koo. 2001. Bacterial biofilm formation under microgravity conditions. FEMS Microbiology Letters 195: 115-119.

 

  • Corbin, BD, RJC McLean, and GM Aron. 2001. Bacteriophage T4 multiplication in a glucose-limited Escherichia coli biofilm. Canadian Journal of Microbiology 47: 680-684.

 

  • Balzer, GJ and RJC McLean. 2002. The stringent response genes relA and spoT are important for Escherichia coli biofilms under nutrient-limited conditions. Canadian Journal of Microbiology 48: 675-680.

 

  • McLean, RJC, LS Pierson III, and C. Fuqua. 2004. A simple screening protocol for the identification of quorum signal antagonists. Journal of Microbiological Methods 58: 351-360.

 

  • McLean, RJC, MB Barnes, MK Windham, M Merchant, MRJ Forstner, and C Fuqua. 2005. Cell-cell influences on bacterial community development in aquatic biofilms.  Applied and Environmental Microbiology 71: 8987-8990.

 

  • Bates, CL, MRJ Forstner, MB Barnes, M Whiteley, and RJC McLean. 2006. Identification of heterotrophic limestone-adherent biofilm isolates from the Edward's aquifer, Texas USA. Southwestern Naturalist 51: 299-309.

 

  • McLean, RJC, AK Welsh, and VA Casasanto. 2006. Microbial survival in space shuttle crash. Icarus 181: 323-325.

 

  • Merchant, MM, AK Welsh, and RJC McLean. 2007. Rheinheimera texasensis sp. nov., a halointolerant freshwater oligotroph. International Journal of Systematic and Evolutionary Microbiology, in press.

 

  • Vattem, DA, K Mihalik, SH Crixell, and RJC McLean. 2007.  Dietary phytochemicals as quorum sensing inhibitors.  Fitoterapia 78: 302-310.

 

  • Kim C, J Kim, HY Park, RJC McLean, CK Kim, J Jeon, SS Yi, YG Kim, YS Lee, and J Yoon. 2007. Molecular modeling, synthesis, and screening of new bacterial quorum-sensing antagonists. Journal of  Microbiology and Biotechnology 17: 1598-1606.

 

  • Mashburn-Warren, L, RJC McLean, and M Whiteley. 2008.  Gram negative outer membrane vesicles:  Beyond the cell surface.  Geobiology, in press.

 

 

BOOKS

  • Veliky, IA and RJC McLean. 1994. Immobilized biosystems theory and practical applications, Blackie Academic and Professional, Glasgow, Scotland, 342 pp.
  • McLean, RJC and AW Decho. 2002. Molecular ecology of biofilms. Horizon Scientific Press, Wymondham, UK, 123 pp.

BOOK CHAPTERS

  • McLean, RJC and TJ Beveridge. 1990. Metal binding capacity of bacterial surfaces and their ability to form mineralized aggregates, p.185-222. In H.L. Ehrlich and C.L. Brierley (ed.), Microbial mineral recovery, McGraw-Hill, New York .
  • McLean, RJC, DE Caldwell, and JW Costerton. 1994. Biofilms, naturally occurring communities of immobilized cells, p.289-335. In IA Veliky and RJC McLean (eds.), Immobilized biosystems theory and practical applications, Blackie Academic and Professional, Glasgow, Scotland.
  •  
  • McLean, RJC, JC Nickel, and ME Olson. 1995. Biofilm associated urinary tract infections, p.261-273. In HM Lappin-Scott and JW Costerton (ed.), Microbial biofilms, Cambridge University Press, Cambridge, UK .
  • McLean, RJC. 2002. An overview of biofilm molecular ecology, In: RJC McLean and AW Decho (eds.), Molecular ecology of biofilms. Horizon Scientific Press, Wymondham, UK, Chapter 1, pp 1-21.
  • Morris, CE, MB Barnes, and RJC McLean. 2002. Biofilms on Leaf Surfaces: Implications for the Biology, Ecology and Management of Populations of Epiphytic Bacteria, In: SE Lindow, EI Hecht-Poinar, and VJ Elliott (eds.), Phyllosphere Microbiology. American Phytopathological Society, St. Paul, MN . Chapter 10, pp 139-155.
  • McLean, RJC, CL Bates, MB Barnes, CL McGowin, and GM Aron. 2004. Methods for studying biofilms, In: MA Ghannoum and GA O’Toole (eds.), Microbial Biofilms, American Society for Microbiology, Washington DC, Chapter 20, pp 379-413.
  •  
  • Welsh, AK and RJC McLean. 2007. Characterization of bacteria in mixed biofilm communities using denaturing gradient gel electrophoresis. In: R Coico, T Kowalik, J Quarles, B Stevenson, and R Taylor (eds) Current Protocols in Microbiology, Unit 1E.1, Wiley Interscience Publishers.


CONFERENCE PROCEEDINGS

  • McLean, RJC, C. Fuqua, D.A. Siegele, B. Kirkland-George, J.L. Adams and M. Whiteley. 2000. Biofilm Growth and an Illustration of its Role in Mineral Formation, IN: Microbial Biosystems: New Frontiers.  Proceedings of the 8th International Symposium on Microbial Ecology .  Bell, C.R., Brylinsky, M and Johnson-Green, P (Editors). Atlantic Canada Society for Microbial Ecology. pp 255 - 261.
  • McLean, RJC.  Biofilms in perspective, IN: Microbial Biosystems: New Frontiers.  Proceedings of the 8th International Symposium on Microbial Ecology.  Bell , C.R., Brylinsky, M and Johnson-Green, P (Editors). Atlantic Canada Society for Microbial Ecology. p 253.

 

Theses Directed

  1. MM Weber 2007.  "Role of yjfO, agaB and atoS in Escherichia coli Biofilm Formation and Stress Response"  MS Thesis, Texas State University-San Marcos

 

  1. W Boswell 2007. "Effects of N-acyl-L-homoserine lactone lactonase on disruption of preformed biofilms, bacterial recruitment, and prevention of biofilms" MS Thesis, Texas State University-San Marcos
  2. MM Merchant 2005. " Identification and Characterization of Bacterial Isolates from Spring Lake, Texas", MS Thesis, Texas State University
  3. AK Welsh 2005. “Detection of an Introduced Bacterial Culture in Greywater Treatment Reactors“, MS Thesis, Texas State University
  4. CL Bates 2004. “Differential Gene Expression and Colanic Acid Gene Effects on Biofilm Formation” MS thesis, Texas State University
  5. KL Fuson 2002. “Biofilm-Induced Gene Expression in Chemostat Grown Escherichia coli as Determined by a Gene Array” MS thesis, Southwest Texas State University
  6. MK Windham 2001. "Acyl Homoserine Lactone Recruitment of Bacteria Into Biofilms" MS thesis, Southwest Texas State University
  7. GJ Balzer 2000. "Effect of relA and spoT Deletions on Escherichia coli Biofilm Formation" MS thesis, Southwest Texas State University
  8. Corbin, B.D. 2000 "Replication of T4 Phage in an Escherichia coli Biofilm", MS thesis, cosupervised with G Aron , Southwest Texas State University
  9. Prabhakaran, S. 1999. "Investigation of Bacterial Fragmentation as a Possible Origin of Nanobacteria" MS thesis, Southwest Texas State University
  10. Adams, J.L.   1998   "Role of rpoS in the Formation and Physiology of Escherichia coli Biofilms" MS thesis, Southwest Texas State University
  11. Knowles, H.C.  1998  "The Isolation, Culturing, and Characterization of Nannobacteria" MS thesis, Southwest Texas State University
  12. Khu, P.T.  1998  "Bacterial Precious Metal Recovery". MSc ( Eng. ) thesis, Queen's University (co-supervised with W.T. Yen , Mining Engineering, Queen's University)
  13. Whiteley, M.  1997  "Effects of Nutrient Limitation and Species Composition on Biofilm Development and Susceptibility to Iodine Disinfection". MS thesis, Southwest Texas State University
  14. Koenig, M.K.  1996  "Parameters Affecting the Conformation of N-acetylneuraminic acid, Escherichia coli K1 Capsular Polysaccharide" MS thesis, Southwest Texas State University
  15. Vincent, P.J.  1995 "Silver-platinum Multilayer Thin Films as Antimicrobial Coatings for Catheters". MSc ( Eng. ) Thesis, Queen's University (co-supervised with M Sayer, Physics, Queen's University)
  16. Persaud, A.T.  1994  "Development of Inductively-Coupled Plasma-Mass Spectrometry for Soil Analysis" MSc Thesis, Queen's University (co-supervised with D Beauchemin, Chemistry and HE Jamieson , Geological Sciences, Queen's University )
  17. Dumanski, A.J.  1992  "Isolation and Characterization of the Capsule of Proteus mirabilis and its Role in Kidney Stone Formation". MSc Thesis, Queen's University

Honors Theses:

  1. V Pearson 2004 “Antibiotic Resistance of Biofilms”. BS Honors Thesis, Texas State University-San Marcos
  2. AR Primmer 1999 "Using Transposon Mutagenesis to Analyze Antibiotic Resistance in Pseudomonas aeruginosa Biofilms". BS Honors Thesis, Southwest Texas State University
  3. EJ Hughes 1996 "Efficiency of Latex Gloves as Barriers to Bacterial and Viral Pathogens". BS Honors Thesis, Southwest Texas State University
  4. HL Bates 1996 "Bacterial Biofilm-Associated Infection in Indwelling Medical Devices". BS Honors Thesis, Southwest Texas State University
  5. KA Dunn 1995 "Role of Bacterial Biofilms in Leaf Fossilization". BS Honors Thesis, Southwest Texas State University (co-supervised with G.R. Upchurch, Biology, Southwest Texas State University)

Students, Research Associates & Postdocs (the Slime Gang)

Slime Gang and Friends, Glove Party 2006 (from left) Diane Fitzgerald (Kimberley-Clark), Jim (Buddy) Gaertner, Bob McLean, Allana Welsh, Shannon Kruse (Cuevas Distributing), Will Boswell, Mikki Boswell, Pejmon Afshar, Monte Gomez, Celeste Whisenant, Mary Weber, and Ian O'Leary