Downloaded from www.microbiologyresearch.org by IP: 54.144.143.175 On: Wed, 04 Jan 2017 05:25:17 Lactobacillus siliginis sp. nov., isolated from wheat sourdough in South Korea Zubair Aslam, 1 Wan-Taek Im, 1 Leonid N. Ten, 1,2 Myung-jin Lee, 1 Kyoung-Ho Kim 1 and Sung-Taik Lee 1 Correspondence Sung-Taik Lee e_stlee@kaist.ac.kr 1 Department of Biological Sciences, Korea Advanced Institute of Science and Technology, 373-1, Guseong-dong, Yuseong-gu, Daejeon 305-701, Republic of Korea 2 National University of Uzbekistan, Students Town, Tashkent 700-174, Uzbekistan The taxonomic position of two lactic-acid-producing bacterial strains, isolated from wheat sourdough in South Korea, was studied using a polyphasic approach. Phylogenetic analysis on the basis of 16S rRNA gene sequences and biochemical and physiological characteristics indicated these two strains to be members of the genus Lactobacillus. They had high 16S rRNA gene sequence similarity (98?5 %) with Lactobacillus rossiae DSM 15814 T and very low (<94?0 %) similarity with any other recognized species of the genus Lactobacillus. These two strains (designated M1-212 T and M2-236) were heterofermentative, facultatively anaerobic, Gram-positive, non-spore-forming, non-motile, short rod-shaped bacteria. The optimum growth temperature for these strains was 30 6C (no growth at 15 or 45 6C) and they were able to tolerate 5 % (w/v) NaCl. The G+C content of the genomic DNA of the two strains was 45?5 mol%, within the range of values reported for the genus Lactobacillus (32–53 mol%). The peptidoglycan was of the A3a (L-Lys–D-Glu–L-Ala) type. Physiological, biochemical and genotypic data, as well as results of DNA–DNA hybridization of the genomic DNA with one of the closest phylogenetic relatives, L. rossiae DSM 15814 T , indicated that the strains represent a novel species of the genus Lactobacillus, for which the name Lactobacillus siliginis sp. nov. is proposed. The type strain is M1-212 T (=KCTC 3985 T =NBRC 101315 T ). Wheat (Triticum aestivum) bread is a staple food in many countries. Moreover, it contributes to cultural and geo- graphical identity. Artisanal bread production, which often employs sourdough processes or the use of pre-fermenta- tions, provides a wide regional variety of breads and speciality products. Sourdough is a mixture of wheat or rye flour and water that is fermented with lactic acid bacteria (LAB) and yeasts (Ga ¨nzle et al., 1998; Vogel et al., 1999). LAB metabolism is responsible for the production of organic acids and contributes, along with yeasts, to the production of aromatic compounds (Damiani et al., 1996; Martinez- Anaya, 1996; Meignen et al., 2001). Wheat flour or wheat sourdough itself is a source of many LAB, and numerous novel species of the genus Lactobacillus have been isolated from wheat sourdough: Lactobacillus sanfranciscensis (Weiss & Schillinger, 1984), L. pontis (Vogel et al., 1994), L. brevis, L. plantarum, L. acidifarinae and L. zymae (Vancanneyt et al., 2005), L. hammesii (Valcheva et al., 2005), L. rossiae (Corsetti et al., 2005) and L. nantensis (Valcheva et al., 2006). In this study, two novel strains of LAB were isolated from a wheat sourdough sample. These strains, designated M1- 212 T and M2-236, were initially characterized on the basis of 16S rRNA gene sequence analysis. Based on results from the API 50 CH test system and other chemotaxonomic and genotypic characteristics, it was shown that these two strains represent a novel species in the genus Lactobacillus. A wheat-flour sample was taken from standard Korean wheat-flour No. 3, produced by DaeHan Flour Mills, Korea (http://www.dhflour.co.kr). Ten grams of wheat-flour was kneaded with 6 ml autoclaved water and 1 % NaCl (w/v) for 10 min on a clean bench. After 24 h incubation at 30 u C, a small portion of the sample was serially diluted and was applied to MRS agar and half-strength MRS agar, pH 5?6, at 30 uC. Bromocresol green (0?022 g l 21 ; Shinyo Pure Chemicals) was used as a pH indicator. Cell numbers were measured by a plating method on MRS agar after incubation at 30 u C for 3–5 days. MRS agar was prepared with Lactobacilli MRS broth (50?0gl 21 , w/v; Difco) and agar powder (15?0gl 21 , w/v; Samchun). Total cell counts of Abbreviation: LAB, lactic acid bacteria. The GenBank/EMBL/DDBJ accession numbers for the 16S rRNA gene sequences of strains M1-212 T and M2-236 are DQ168027 and DQ168028, respectively. Figures showing cells of strain M1-212 T and PCR-generated DNA fingerprints of strains M1-212 T , M2-236 and L. rossiae DSM 15814 T are available as supplementary material in IJSEM Online. 64321 G 2006 IUMS Printed in Great Britain 2209 International Journal of Systematic and Evolutionary Microbiology (2006), 56, 2209–2213 DOI 10.1099/ijs.0.64321-0