Systematic and Applied Microbiology 32 (2009) 593–600 Isolation and characterization of fructophilic lactic acid bacteria from fructose-rich niches Akihito Endo à , Yuka Futagawa-Endo, Leon M.T. Dicks Department of Microbiology, University of Stellenbosch, De Beer Street, Stellenbosch 7600, Western Cape, South Africa Received 3 July 2009 Abstract Fourteen strains of fructophilic lactic acid bacteria were isolated from fructose-rich niches, flowers, and fruits. Phylogenetic analysis and BLAST analysis of 16S rDNA sequences identified six strains as Lactobacillus kunkeei, four as Fructobacillus pseudoficulneus, and one as Fructobacillus fructosus. The remaining three strains grouped within the Lactobacillus buchneri phylogenetic subcluster, but shared low sequence similarities to other known Lactobacillus spp. The fructophilic strains fermented only a few carbohydrates and fermented D-fructose faster than D-glucose. Based on the growth characteristics, the 14 isolates were divided into two groups. Strains in the first group containing L. kunkeei, F. fructosus, and F. pseudoficulneus grew well on D-fructose and on D-glucose with pyruvate or oxygen as external electron acceptors, but poorly on D-glucose without the electron acceptors. Strains in this group were classified as ‘‘obligately’’ fructophilic lactic acid bacteria. The second group contained three unidentified strains of Lactobacillus that grew well on D-fructose and on D-glucose with the electron acceptors. These strains grew on D-glucose without the electron acceptors, but at a delayed rate. Strains in this group were classified as facultatively fructophilic lactic acid bacteria. All fructophilic isolates were heterofermentative lactic acid bacteria, but ‘‘obligately’’ fructophilic lactic acid bacteria mainly produced lactic acid and acetic acid and very little ethanol from D-glucose. Facultatively fructophilic strains produced lactic acid, acetic acid and ethanol, but at a ratio different from that recorded for heterofermentative lactic acid bacteria. These unique characteristics may have been obtained through adaptation to the habitat. & 2009 Elsevier GmbH. All rights reserved. Keywords: Fructophilic lactic acid bacteria; Lactobacillus; Fructobacillus; Fructose-rich niches; External electron acceptors Introduction Lactic acid bacteria (LAB) are found in various niches, such as the gastrointestinal tract of animals, plant materials, dairy products, and fermented food [13]. It is known that adaptation to new environments often leads to the loss of certain phenotypic characteristics [22,27]. The genus Fructobacillus stemmed from the reclassi- fication of four Leuconostoc spp. based on their phylogenetic positions and biochemical and morpholo- gical characteristics [11]. The type species is Fructoba- cillus fructosus. Fructobacillus spp. have unique characteristics, meaning that they grow well on D-fructose or D-glucose in the presence of external electron acceptors, but poorly on D-glucose without ARTICLE IN PRESS www.elsevier.de/syapm 0723-2020/$ - see front matter & 2009 Elsevier GmbH. All rights reserved. doi:10.1016/j.syapm.2009.08.002 Abbreviations: LAB, lactic acid bacteria; ADH, alcohol dehydro- genase; ALDH, acetaldehyde dehydrogenase. à Corresponding author. Tel.: +27 21 808 5850; fax: +27 21 808 5846. E-mail address: pegaman@hotmail.co.jp (A. Endo).