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Applied and Environmental Microbiology, August 2009, p. 5018-5024, Vol. 75, No. 15
0099-2240/09/$08.00+0     doi:10.1128/AEM.02837-08
Copyright © 2009, American Society for Microbiology. All Rights Reserved.

Biochemical Properties of Two Cinnamoyl Esterases Purified from a Lactobacillus johnsonii Strain Isolated from Stool Samples of Diabetes-Resistant Rats{triangledown}

Kin Kwan Lai, Graciela L. Lorca, and Claudio F. Gonzalez*

Genetics Institute, Department of Microbiology and Cell Science, University of Florida, Gainesville, Florida 32610-3610

Received 15 December 2008/ Accepted 1 June 2009

Cinnamic acids (i.e., ferulic and caffeic acids) that are esterified to the vegetable cell walls should be enzymatically released to be absorbed in a mammal's intestines. A low dosage of ferulic acid in rodent diets stimulates insulin production and alleviates symptoms caused by diabetes (M. Sri Balasubashini, R. Rukkumani, and V. P. Menon, Acta Diabetol. 40:118-122, 2003). Several lactic acid bacteria are able to display ferulic acid esterase (FAE) activity, suggesting that their probiotic activity could be, in part, mediated by the slow release of ferulic acid. In the present work, we describe the isolation of one strain identified as being Lactobacillus johnsonii that displayed strong FAE activity in stool samples from diabetes-resistant biobreeding rats. These animals are genetically susceptible to becoming diabetic but do not develop the disease. By using genomic analysis coupled to protein purification and catalytic screening, we were able to purify two proteins with FAE activity. The enzymes displayed 42% sequence identity and a broad range of substrate preferences. High affinities and catalytic efficiencies toward aromatic compounds such as ethyl ferulate (Km = 20 to 60 µM) and chlorogenic acid (Km = 10 to 50 µM) were observed. The strain isolated herein as well as the enzymes studied could be potentially useful for the formulation of probiotics to ameliorate diabetes symptoms.

* Corresponding author. Mailing address: Genetics Institute, Department of Microbiology and Cell Science, University of Florida, P.O. Box 103610, 1376 Mowry Rd., Gainesville, FL 32610-3610. Phone: (352) 273-8088. Fax: (352) 273-8284. E-mail: cfgonzalez{at}ufl.edu

{triangledown} Published ahead of print on 5 June 2009.

Applied and Environmental Microbiology, August 2009, p. 5018-5024, Vol. 75, No. 15
0099-2240/09/$08.00+0     doi:10.1128/AEM.02837-08
Copyright © 2009, American Society for Microbiology. All Rights Reserved.





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