This study was performed to discover bifidobacteria isolated from human intestines that optimally convert linoleic acid (LA) to conjugated linoleic acid (CLA) and to optimize the culture conditions of milk fermentation. One hundred and fifty neonatal bifidobacteria were screened for CLA-producing ability, and Bifidobacterium breve LMC 017 was selected as it showed about 90% conversion of free LA in MRS broth. The selected strain showed resistance at 0.5% LA in microaerophillic conditions. When monolinolein (LA 90%) was used as a substrate for CLA production, the conversion rate was lower compared to free LA, but the growth rate was unaffected during the milk fermentation. There was no significant difference in CLA production between aerobic and anaerobic conditions, and little decline in CLA was shown after the maximal CLA level had been reached. CLA production increased by 80% with 24 h of incubation in milk containing additional skim milk (5%), where the proteins may have facilitated the production of CLA by enhancing the interaction of substrate with the bacteria. CLA production did not decline after 9 h of fermentation and an additional 12 weeks of storage with other commercial starters. This demonstrates the possibility of using this strain as a costarter in the production of CLA-enriched yogurt.
An aerobic, Gram-negative, catalase-positive, oxidase-positive bacterium was isolated from a dried seaweed sample collected from Kimnyeong Beach in Jeju, Republic of Korea. The cells of the organism, designated strain KY 101 T , were rods (0.4-0.5¾1.2-2.7 mm) and motile by means of flagella. The colonies of the cells were 0.5-1 mm in diameter, smooth, circular, convex and light yellow in colour. The isolate showed growth at 10-40 6C, pH 6.1-12.1 and in the presence of 7 % NaCl. The major fatty acid was summed feature C 18 : 1 v7c/C 18 : 1 v9c/C 18 : 1 v12t and the DNA G+C content was 60.4 mol%. 16S rRNA gene sequence studies showed that the organism was phylogenetically related to the family Phyllobacteriaceae, with Nitratireductor aquibiodomus (99.1 % sequence similarity) as the closest neighbour.
An aerobic, Gram-reaction-negative, non-motile, catalase-and oxidase-positive bacterium, designated strain MDSW-25 T , was isolated from seaweed collected in the vicinity of Mara Island in Jeju province, Republic of Korea. Colonies were smooth, circular and convex with entire edges and yellow in colour. Growth occurred at 10-30 6C, at pH 6.1-9.1 and in the presence of 1-12 % (w/v) NaCl. The major fatty acids were iso-C 15 : 0 (25.6 %) and iso-C 15 : 1 G (11.3 %), and the major menaquinone was MK-6. The DNA G+C content was 30.0 mol%. Phylogenetic analysis based on 16S rRNA gene sequence showed that strain MDSW-25 T belonged to the genus Mesonia, family Flavobacteriaceae. Sequence similarity with Mesonia mobilis and Mesonia algae was 97.5 and 95.4 %, respectively, but DNA relatedness between strain MDSW-25 T and M. mobilis KCTC 12708 T was only 47 %. A battery of phenotypic data, phylogenetic inference and DNA-DNA hybridization analyses supports the conclusion that strain MDSW-25 T (5KCTC 22373 T 5DSM 21425 T ) represents a novel species of the genus Mesonia, for which the name Mesonia phycicola sp. nov. is proposed. On the basis of new data obtained in this study, an emended description of the genus Mesonia is also proposed.The genus Mesonia and the species Mesonia algae were described by Nedashkovskaya et al. (2003) to accommodate a Gram-reaction-negative, strictly aerobic, heterotrophic, yellow-pigmented, non-motile strain isolated from green algae. In contrast, Mesonia mobilis, subsequently isolated from seawater, is motile by means of gliding (Nedashkovskaya et al., 2006). The genus Mesonia is a member of the family Flavobacteriaceae, phylum Bacteroidetes (Nedashkovskaya et al., 2003). In this study, a seaweed isolate was subjected to a polyphasic taxonomic characterization. The results justify the description of a new species of the genus Mesonia.Strain MDSW-25 T was isolated from a seaweed sample collected in the vicinity of Mara Island in Jeju province, Republic of Korea. The procedure and agar medium used for bacterial isolation was described previously (Lee, 2006). A colony was transferred onto marine agar (MA; Difco) at 30 uC. The pure culture was preserved as a suspension in natural seawater, distilled water and glycerol (60/20/20, by vol.). Mesonia algae KCTC 12908 T and M. mobilis KCTC 12708 T were grown on MA at 30 u C, studied in parallel with strain MDSW-25 T for phenotypic investigations and used as references in DNA-DNA hybridization experiments.Cell morphology was observed by using phase-contrast and transmission electron microscopy, using cells grown on MA for 5 days at 30 u C. The cells were negatively stained with 1 % phosphotungstic acid and the grid, after airdrying, was observed with a model 1200EXII transmission electron microscope (JEOL). Gliding motility was assessed by phase-contrast microscopy using the hanging drop technique (Bernardet et al., 2002) after growing cells in 0.16 marine broth (MB; Difco) for 24 h at 30 u C, with M. mobilis KCTC 12708 T as a positive control and M. alg...
This study was designed to isolate bifidobacteria from human intestines that efficiently converts monolinolein, a monoglyceride form of linoleic acid, into conjugated linoleic acid (CLA), as well as to optimize culture conditions for improving CLA production during milk fermentation. Among 150 screened neonatal bifidobacteria, Bifidobacterium breve LMC 520 showed the highest CLA-producing ability and was tested with different types of fat substrates at various concentrations to determine the optimal conditions for CLA production. Monolinolein was tested as a substrate for CLA production. The incubation time optimized for CLA production was 24 h, and CLA production was proportionally increased with monolinolein concentration. The incubation of LMC 520 with commercial starter strains caused minimal reduction in CLA production. Our results demonstrate that the CLA-producing ability of B. breve LMC 520 could offer beneficial effects when utilized as a starter culture for the development of functional dairy products.
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