James L. SteeleProfessor, Food Science
127B Babcock Hall
FAX (608) 262-6872
My research group is examining the genetics and physiology of lactic acid bacteria. This group of organisms is used in a variety of food and industrial fermentations, as well as probiotics. My group's primary focus is on Lactobacillus casei. This species has a high level of genetic variability; with a typical genome consisting of 61% core genes and 39% variable genes. Our interest in genetic variation within this species has both applied and basic perspectives. We are interested in how selective pressure in different environments strains has resulted in variations in gene content. Additionally, we are interested in how this variation impacts the utility of different L. casei strains as adjunct flavor cultures in cheese ripening, as biocatalyst for the production of biofuels and co-products, and as immunomodulatory probiotics. We are particularly interested in metabolic flux through pyruvate as we believe it key to both cheese flavor development and the utility of this organism as a biofuels biocatalyst. Finally, we are screening strains of L. casei for their ability to modulate the host immune system and reduce the incidence and severity of Clostridium difficile infections.
I believe that conducting research in an applied field requires a strong background in both the basic sciences and in the applied field of choice. In my research area, a background in genetics, biochemistry, microbiology and food science is essential.
Scientific and Professional Organizations
Makarova, K., A. Slesarev, Y. Wolf, A. Sorokin, B. Mirkin, E. Koonin, A. Pavlov, N. Pavlova, V. Karamychev, N. Polouchine, V. Shakhova, , I. Grigoriev, Y. Lou, D. Rohksar, S. Lucas, K. Huang, D. M. Goodstein, T. Hawkins, V. Plengvidhya, D. Welker, J. Hughes, Y. Goh, A. Benson, K. Baldwin, J.-H. Lee, I. Diaz-Muniz, B. Dosti, V. Smeianov, W. Wechter, R. Barabote, G. Lorca, E. Altermann, R. Barrangou, B. Ganesan, Y. Xie, H. Rawsthorne, D. Tamir, C. Parker, L. McKay, F. Breidt, J. Broadbent, R. Hutkins, D. O'Sullivan, J. Steele, G. Unlu, M. Saier, T. Klaenhammer, P. Richardson, S. Kozyavkin, B. Weimer, and D. Mills. 2006. Comparative genomics of the lactic acid bacteria. Proc. Natl. Acad. Sci. 103:15611-15616.
Cai, H., B.T. Rodriguez, W. Zhang, J.R. Broadbent and J.L. Steele. 2007. Genotypic and phenotypic characterization of Lactobacillus casei strains isolated from different ecological niches suggests frequent recombination and niche specificity. Microbiol. 153:2655-2665.
Christiansen, J.K., J.E. Hughes, D.L. Welker, B.T. Rodriguez, J.L. Steele, and J.R. Broadbent. 2008. Phenotypic and genotypic analysis of amino acid auxotrophy in Lactobacillus helveticus CNRZ 32. Appl. Environ. Microbiol. 74:416-423.
Cai, H., R.L. Thompson, J.R. Broadbent and J.L. Steele. 2009. Genome Sequence and Comparative Genome Analysis of Lactobacillus casei: Insights into their Niche-associated Evolution. Genome Biol. and Evol. 1:239-257.
Broadbent, J.R., R.L. Larsen, V. Deibel, and J.L. Steele. 2010. Physiological and transcriptional response of Lactobacillus casei ATCC 334 to acid stress. J. Bacteriol. 192: 2445-2458.
Budinich, M.F., I. Diaz-Muniz, H. Cai, S.A. Rankin, J.R. Broadbent and J.L. Steele. 2011. Growth of Lactobacillus paracasei ATCC 334 in a cheese model system: A biochemical approach. J. Dairy Sci. 94:5263-5277.
Broadbent, J.R., E.C. Neeno-Eckwall, B. Stahl, K. Tandee, H. Cai, W. Morovic, P. Horvath, J. Heidenreich, R. Barrangou, N.T. Perna and J.L. Steele. 2012. Characterization of the Lactobacillus casei supragenome and its role in evolution and lifestyle adaptation. BMC Genomics 13:533.