Kimoto-Nira Hiromi, Kobayashi Miho, Nomura Masaru, Sasaki Keisuke, Suzuki Chise
National Institute of Livestock and Grassland Science, 2 Ikenodai, Tsukuba, Ibaraki 305-0901, Japan.
Int J Food Microbiol. 2009 May 31;131(2-3):183-8. doi: 10.1016/j.ijfoodmicro.2009.02.021. Epub 2009 Mar 3.
Bile resistance is one of the basic characteristics of probiotic bacteria. The aim of this study was to investigate the characteristics of bile resistance in lactococci by studying the relationship between bile resistance and cellular fatty acid composition in lactococcci grown on different media. We determined the bile resistance of 14 strains in lactose-free M17 medium supplemented with either glucose only (GM17) or lactose only (LM17). Gas chromatographic analyses of free lipids extracted from the tested strains were used for determining their fatty acid composition. A correlation analysis of all strains grown in both media revealed significant positive correlations between bile resistance and relative contents of hexadecanoic acid and octadecenoic acid, and negative correlations between bile resistance and relative contents of hexadecenoic acid and C-19 cyclopropane fatty acid. It is also a fact that the fatty acids associated with bile resistance depended on species, strain, and/or growth medium. In L. lactis subsp. cremoris strains grown in GM17 medium, the bile-resistant strains had significantly more octadecenoic acid than the bile-sensitive strains. In LM17 medium, bile-resistant strains had significantly more octadecenoic acid and significantly less C-19 cyclopropane fatty acid than the bile-sensitive strains. In L. lactis subsp. lactis strains, bile resistances of some of the tested strains were altered by growth medium. Some strains were resistant to bile in GM17 medium but sensitive to bile in LM17 medium. Some strains were resistant in both media tested. The strains grown in GM17 medium had significantly more hexadecanoic acid and octadecenoic acid, and significantly less tetradecanoic acid, octadecadienoic acid and C-19 cyclopropane fatty acid than the strains grown in LM17 medium. In conclusion, the fatty acid compositions of the bile-resistant lactococci differed from those of the bile-sensitive ones. More importantly, our data suggest that altering their fatty acid composition (i.e. increased hexadecanoic acid and octadecenoic acid and decreased hexadecenoic acid and C-19 cyclopropane fatty acid) by changing growth conditions may be a useful way to enhance their bile resistance in lactococci.
胆汁抗性是益生菌的基本特性之一。本研究的目的是通过研究不同培养基上生长的乳酸球菌的胆汁抗性与细胞脂肪酸组成之间的关系，来探究乳酸球菌的胆汁抗性特征。我们测定了在仅添加葡萄糖（GM17）或仅添加乳糖（LM17）的无乳糖M17培养基中14株菌株的胆汁抗性。对从受试菌株中提取的游离脂质进行气相色谱分析，以确定其脂肪酸组成。对在两种培养基中生长的所有菌株进行的相关性分析表明，胆汁抗性与十六烷酸和十八烯酸的相对含量之间存在显著正相关，与十六碳烯酸和C-19环丙烷脂肪酸的相对含量之间存在负相关。与胆汁抗性相关的脂肪酸也取决于菌种、菌株和/或生长培养基。在GM17培养基中生长的乳酸乳球菌乳脂亚种菌株中，胆汁抗性菌株的十八烯酸含量显著高于胆汁敏感菌株。在LM17培养基中，胆汁抗性菌株的十八烯酸含量显著更高，而C-19环丙烷脂肪酸含量显著低于胆汁敏感菌株。在乳酸乳球菌乳酸亚种菌株中，一些受试菌株的胆汁抗性因生长培养基而异。一些菌株在GM17培养基中对胆汁有抗性，但在LM17培养基中对胆汁敏感。一些菌株在两种受试培养基中均有抗性。在GM17培养基中生长的菌株比在LM17培养基中生长的菌株含有显著更多的十六烷酸和十八烯酸，以及显著更少的十四烷酸、十八碳二烯酸和C-19环丙烷脂肪酸。总之，胆汁抗性乳酸球菌的脂肪酸组成与胆汁敏感乳酸球菌不同。更重要的是，我们的数据表明，通过改变生长条件来改变其脂肪酸组成（即增加十六烷酸和十八烯酸，减少十六碳烯酸和C-19环丙烷脂肪酸）可能是提高乳酸球菌胆汁抗性的一种有效方法。
