PhD, Stanford University MS, Stanford University BS, Cornell University

Environmental microbiology, microbial metal oxidation and reduction, Cyanobacterial macromorphology, geomicrobiology, bioremediation, and water quality.

Deller, M.C., Johnson, H.A., Miller, M.D., Spraggon, G., Elsliger, M.A., Wilson, I.A., and Lesley, S.A. Crystal structure of a two-subunit TrkA octameric gating ring assembly. PLoS One 10(3): e0122512. 2015. Nakama, K., Medina, M., Lien, A., Ruggieri, J., Collins, K., and Johnson, H.A. Heterologous expression and characterization of the manganese oxidizing protein from Erythrobacter sp. strain SD21. Applied and Environmental Microbiology 80(21): 6837-42. 2014. Banh, A., Chavez, V., Doi, J., Nguyen, A., Hernandez, S., Ha, V., Jimenez, P., Espinoza, F., and Johnson, H.A. Manganese (Mn) oxidation increases intracellular Mn in Pseudomonas putida GB-1. PLoS One 8(10): e77835. 2013. Reyes, K., Gonzalez, N.I., Stewart, J., Ospino, F., Nguyen, D., Cho, D.T., Ghahremani, N., Spear, J.R., and Johnson, H.A. Surface orientation affects the direction of cone growth by Leptolyngby sp. strain C1, a likely architect of coniform structures in Octopus Spring (Yellowstone National Park). Applied and Environmental Microbiology 79(4): 1302-8. 2013. Cover image. 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. A . The 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 α -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.