Education

  • Doctor of Philosophy - Stanford University (3/2001)
  • Environmental Engineering and Science
    With an emphasis on Microbiology and Biochemistry

  • Master of Science - Stanford University (6/1994)
  • Environmental Engineering and Science

  • Bachelor of Science - Cornell University (5/1993)
  • (with distinction)
    Civil and Environmental Engineering

  • Microbial Diversity - Marine Biological Laboratory (1997)
  • Woods Hole, Massachusetts

    Academic/Research Positions

    Assistant professor
    Department of Biological Sciences, California State University Fullerton, 8/2008 – present.
    •  Teaching in genetics and molecular biology and microbiology.
    •  Research interests include interactions between microbes and metals with an emphasis on the physiology and biochemistry of bacterial manganese oxidation.  Research students include 3 Master of Science and 8 undergraduate students.

    Scientific Associate
    The Joint Center for Structural Genomics, The Scripps Research Institute, 6/2007 – 6/2008.
    (PI:  Dr. Scott Lesley).
    •  Identification of protein function in the thermophilic microorganism Thermotoga 
    maritima by ligand screening, genetic complementation, biochemical assays, and protein crystallization and structure determination.
    •  Regularly identify and review additional funding opportunities.
    •  Supervise 1 research technician, 1 undergraduate  

    Post Doctoral Research Associate
    The Joint Center for Structural Genomics, The Scripps Research Institute, 4/2006-6/2007.
    (PI:  Dr. Scott Lesley).
    Functional identification and characterization of proteins in Thermotoga maritima.
    •  Used activity based protein probes with multi dimensional protein MS to identify new serine hydrolases.
    •  Confirmed in vitro activity of glutathione S transferase with novel structural fold.
    •  Characterized potassium transporter protein complex by genetic complementation, ligand binding, and site directed mutagenesis.
    •  Implemented high throughput ligand screening to identify cofactors and substrates of hypothetical proteins.
    •  Mentored/directed high school student and research technician.

    Postgraduate Researcher
    Marine Biological Research Division, Scripps Institution of Oceanography, UCSD, 3/2002-3/2006.
    (PI:  Dr. Bradley M. Tebo).
    Investigated microbial Mn(II) oxidation. 
    •  Protein purification and characterization of novel Mn(II) oxidase.
    •  Linked molecular and biochemical studies.
    •  Enzyme assay development. 
    •  Transposon mutagenesis used to identify genes involved in Mn(II) oxidation. 
    •  Collaborated with protein MS/MS experts to identify novel proteins.
    •  Genome annotation and analysis.
    •  Growth studies and RNA extraction for microarray analysis.
    •  Method development to identify enzymatic activity in environmental samples. 
    •  Set-up protein purification laboratory. 
    •  Mentored and advised high school (1), undergraduate (2) and graduate students (1), post doctoral researcher (1). 

    Graduate Research Assistant
    Department of Civil and Environmental Engineering, Stanford University, 9/1994-4/2001.
    (PI: Dr. Alfred Spormann).
    Thesis:  A physiological and biochemical characterization of anaerobic ethylbenzene oxidation.
    •   Isolated and characterized a new anaerobic microorganism via growth and molecular
        experiments.
    •  Elucidated the initial reactions of anaerobic ethylbenzene metabolism in whole cells.
    •  Developed in vitro enzyme assays and used them to characterize the initial enzymatic
        reactions.
    •  Purified and characterized a novel membrane associated enzyme activity (ethylbenzene  
       dehydrogenase).
    •  Mentored undergraduate and graduate students.

    Undergraduate Research:
    Department of Civil and Environmental Engineering, Cornell University, 1992.
    (Research advisor: Dr. Richard Dick).
    Investigated factors affecting sludge dewaterability assessment.
                Funded by GE Faculty for the Future Research Experience for Undergraduates.

    Department of Materials Science, Cornell University, 1991.
    (Research advisor: Dr. Chris Ober).
                Investigated diffusion properties and thermal stability of liquid crystal polymers.

    Teaching Experience

    Assistant professor, Biological Sciences, California State University Fullerton.  Fall 2008- present.
                Taught 3rd semester core curriculum biology course for majors. Course included Mendelian and non-Mendelian genetics and inheritance; chromosome structure and function; meiosis; structure and function of nucleic acids; mechanism of DNA replication, transcription, and translation; recombinant DNA technology, population genetics.  Laboratory coordination.
                Taught General Microbiology for majors.  Course included cell structure, growth, metabolism, genetics, regulation and signaling, virology, immunology, microbe-host interactions, and microbial ecology.  Laboratory coordination.

    Instructor for international geobiology course, University of Southern California, Wrigley Institute for Environmental Studies, Catalina Island, California, summer 2005, 2006, 2008, 2010.
    Designed and delivered lectures, set-up microbial culturing laboratory, taught laboratory exercises on culturing and molecular techniques, assisted with independent student project design and implementation.  Field experiments on phenotypic diversity.  Identification of enzyme activities in field samples.  Sample preparation for elemental analysis.  Emphasized bacterial culturing and metal cycling in lectures and laboratory.

    Guest lecturer for graduate geochemistry class - The Biogeochemistry of Carbon and Nitrogen, Scripps Institution of Oceanography, University of California, San Diego, La Jolla, California, October, 2006.
    Designed and lectured/led discussion on bioenergetics using aerobic and anaerobic ammonia oxidation in the marine environment as timely and relevant examples from the literature.

    Guest laboratory instructor for environmental microbiology laboratory, University of California, San Diego, La Jolla, California, April 2005.
    Introduced/reviewed the concept of chemolithotrophy and directed students in making gradient tubes for culturing this class of microorganism.

    Laboratory instructor/teaching assistant for international geobiology course.  University of Southern California, Wrigley Institute for Environmental Studies, Catalina Island, California, June 27-July 3, 2004.
    Introduced different types of culturing and enrichment techniques to the laboratory class with an emphasis on microorganisms involved in metal cycling.

    Teaching assistant for Microbial Diversity course, Marine Biological Laboratory, Woods Hole, Massachusetts, Summer 2000.
    Provided technical expertise and analytical method development, organized and directed laboratory activities for internationally renowned intensive summer course for graduate students, post-doctoral researchers, and faculty in microbial diversity.

    Guest lecturer for environmental microbiology course, Stanford University, Stanford, California, 1999.
    Designed and delivered several lectures for graduate environmental microbiology course.

    Teaching assistant for environmental microbiology laboratory and lecture courses, Stanford University, Stanford, California, 1996, 1997, and 1999.
    Led discussion and laboratory exercises.  Planned and prepared laboratory experiments.

    Students Mentored

    Current: 
    M.S.:  Anh Lien, SeongEun Kim, Katherine Nakama.
    Undergraduates: Dickie Nguyen, Nicolas Gonzalez, Valarie Chavez, Peter Jimenez, Fernanda Espinoza, Justin Davis, Alex L. Nguyen, Andy Banh.

    Former Students:
    Kritina Reyes (Awarded Best Honors Thesis, 2010), David Cho, Alex Nguyen, Nahal Ghahremani, Ralph Gozun, Jenny Gong (HHMI- Summer Undergraduate), Wendy Hu (HHMI- High School Student), Sasha Rassoli (HHMI – High School Student), Valerie Thompson (HHMI – High School Teacher).

    Oral Presentations

    Johnson, H. A.  Microbial Mn(II) oxidation.  Biological Science Seminar Series, California State University Los Angeles, California, March, 2010.  Invited Talk.

    Johnson, H.A.  For the love of manganese, from engineering to geomicrobiology.  SACNAS National Conference, Dallas, Texas, October, 2009.  Invited Talk.

    Johnson, H.A.  Geobiology of bacterial mineral formation.  Osher Lifelong Learning Institute at the California State University Fullerton, California, July 2009.  Invited Talk.

    Johnson, H.A., Spraggon, G., Hampton, E., and Lesley, S.A.  Thermotoga maritima’s TrkA (TM1088) – from frameshift to function. Presented at the San Diego Microbiology Group Annual Meeting, San Diego, California.  May 2009.

    Johnson, H.A., Spraggon, G., Hampton, E., and Lesley, S.A.  Thermotoga maritima TrkA – from frameshift to function. Presented at the West Coast Bacterial Physiologists Asilomar Conference, Asilomar, California.  December 2008.

    Johnson, H.A. and Lesley, S.A.  Ligand binding for function and crystallization.  Presented at the Joint Center for Structural Genomics Annual Meeting and Review.  April 2008.

    Johnson, H.A. and Lesley, S.A.  Functional annotation of Thermotoga maritima proteins. Presented at the San Diego Microbiology Group Annual Meeting, San Diego, California.  May 2007.

    Johnson, H.A. and Lesley, S.A.  Approaches to ligand screening and functional annotation of Thermotoga maritima targets.  Presented at the Joint Center for Structural Genomics Annual Meeting and Review.  April 2007

    Johnson, H.A. and Tebo, B.M.  The Mn(II) oxidase of Erythrobacter sp. SD21.  Presented at the San Diego Microbiology Group Annual Meeting, San Diego, California.  May 2006.

    Johnson, H.A. and Tebo, B.M.  Coenzymes in Mn(II) oxidation:  in-vitro studies on Erythrobacter sp. SD21.  Presented at the Joint International Symposia for Subsurface Microbiology (ISSM 2005) and Environmental Biogeochemistry (ISEB XVII), Jackson Hole, Wyoming.  August 2005.

    Johnson, H.A. and Tebo, B.M.  Evidence for required coenzymes in Mn(II) oxidation:  in-vitro studies on Erythrobacter sp. SD21.  Presented at the West Coast Bacterial Physiologists Asilomar Conference, Asilomar, California.  December 2004.

    Johnson, H.A., Ball, H.A., Pelletier, D., and Spormann, A.M.  A physiological and biochemical characterization of anaerobic ethylbenzene degradation.  Presented at the Stanford University Bug Club Seminar, Stanford, California. March 2001.

    Johnson, H.A. and Spormann, A.M.  In vitro studies on ethylbenzene dehydrogenase, the first enzyme of anaerobic ethylbenzene mineralization.  Presented at the West Coast Bacterial Physiologists Asilomar Conference, Asilomar, California.  December 1999.

    Johnson, H.A., Ball, H.A., and Spormann, A.M. Anaerobic ethylbenzene oxidation in denitrifying strain EB1.  Presented at the Environmental Engineering and Science Seminar, Stanford University, Stanford, California.  Autumn 1998.

    Publications

    Deller, M., Johnson, H.A., Miller, M.D., Spraggon, G., Elsliger, M., Wilson, I., and Lesley, S. A. Crystal structure of an octomeric two-subunit TrkA from Thermotoga maritima.  Manuscript submitted to Structure.

    Anderson, C.R., Johnson, H.A., Caputo, N., Davis, R.E., Torpey, J.W., and Tebo, B.M. Mn(II) oxidation is catalyzed by heme peroxidases in "Aurantimonas manganoxydans" strain SI85-9A1 and Erythrobacter sp. strain SD-21. Applied and Environmental Microbiology 75(12):4130-8.  2009.

    Johnson, H.A., Hampton, E. and Lesley, S. AThe Thermotoga maritima Trk potassium transporter – from frameshift to function.  Journal of Bacteriology 191:  2276-84.  2009.

    Dick, G.J., Podell, S., Johnson, H.A., Rivera-Espinoza, Y., Bernier-Latmani, R., McCarthy, J.K., Torpey, J.W., Clement, B.G., Gaasterland, T., and Tebo, B. M.  Genomic insights into Mn(II) oxidation by the marine a-proteobacterium Aurantimonas sp. strain SI85-9A1. Applied and Environmental Microbiology 74:  2646-58.  2008.

    Johnson, H.A. and Tebo, B.M. In vitro studies indicate a quinone is involved in bacterial Mn(II) oxidation.   Archives of Microbiology 189:  59-69. 2008.

    Kosloff, et al. (59 authors).  Comparative structural analysis of a novel glutathione S-transferase (Atu5508) from Agrobacterium tumefaciens at 2.0Å resolution.  Proteins, 65:  527-537.  2006.  (26th author, confirmed function of protein with activity based assays).

    Tebo, B.M., Johnson, H.A., McCarthy, J. Templeton, A.S.  Geomicrobiology of manganese(II) oxidation.  TRENDS in Microbiology, 13:  421-428.  2005.

    Johnson, H. A., Pelletier, D., and Spormann, A. M.  Isolation and characterization of anaerobic ethylbenzene dehydrogenase, a novel Mo-Fe-S enzyme.  Journal of Bacteriology, 183: 4536-4542. 2001.

    Johnson, H. A. and Spormann, A. M. In vitro studies on the initial reactions of anaerobic ethylbenzene mineralization.  Journal of Bacteriology, 181: 5662-5668.  1999.

    Ball, H. A., Johnson, H. A., Reinhard, M., and Spormann, A. M. Initial reactions in anaerobic ethylbenzene oxidation by a denitrifying bacterium, Strain EB1.  Journal of Bacteriology, 178: 5755-5761.  1996.

    Recent Poster Presentations

    * denotes student presenter

    CSUPERB CSU Biotechnology Symposium, San Jose, CA – January, 2010
    Reyes, K.*, Cho, D.T.*, Ghahremani, N. and Johnson, H.A. A study of coniform stromatolitic structures found in Octopus Spring, Yellowstone National Park.

    Chavez, V.*, Jimenez, P.*, and Johnson, H.A.  Accumulation of intracellular Mn(II) in Erythrobacter sp. SD-21 in Mn(II) oxidizing conditions.

    Gozun, R.*, Nguyen, A.*, Gong, J., and Johnson, H.A.  Possible benefits of manganese oxidation to Pseudomonas putida GB1 and Erythrobacter sp. SD21.

     

    Southern California Geobiology Symposium, Pasadena, CA – April 2010
    Reyes, K.*, Cho, D.T.*, Ghahremani, N. and Johnson, H.A. A study of coniform stromatolitic structures found in Octopus Spring, Yellowstone National Park.

    Lien, A.*, Davis, J., and Johnson, H.A.  Heterologous expression and characterization of a manganese(II) oxidizing peroxidase of alpha-proteobacteria.

     

    Southern California Academy of Sciences, Los Angeles, CA – May 2010
    Reyes, K.*, Cho, D.T.*, Ghahremani, N. and Johnson, H.A. A study of coniform stromatolitic structures found in Octopus Spring, Yellowstone National Park.

     

    American Society for Microbiology General Meeting, San Diego, CA – May, 2010

    Lien, A.* and Johnson, H.A.  Heterologous expression and characterization of a manganese(II) oxidizing peroxidase of alpha-proteobacterium Erythrobacter sp. SD21.

    External Funding

    Research Corporation for Science Advancement:  $35,000