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See detailDetermination of phospholipids extracted from Tsukamurella paurometabola C-924 after freeze-drying and during the subsequent storage.
Coulibaly, Ibourahema ULg; Yao, Amenan Anastasie ULg; Dubois Dauphin, Robin ULg et al

Poster (2009, April 01)

The total lipids of Tsukamurella paurometabola C-924 were analysed after freeze-drying. Seven individual lipids classes were identified namly neutral lipids (NLs), fatty acids (FAs), phospholipids (PLs ... [more ▼]

The total lipids of Tsukamurella paurometabola C-924 were analysed after freeze-drying. Seven individual lipids classes were identified namly neutral lipids (NLs), fatty acids (FAs), phospholipids (PLs), sterol ester (SEs), triglycerides (TGs), diglycerides (DGs) and monoglycerides (MGs). The principal fatty acids identified in most lipid classes were palmitic (C16:0), palmitoleic (C16:1), oleic (C18:1), linoleic (C18:2), and linolenic (C18:3). PLs were the major constituents and accounted for 50-60% of the total lipids. PLs were fractionated. . PLs of Tsukamurella paurometabola content phosphatidic acid (PA), phosphatidylethanolamine (PE), phosphatidylinositol (PI), phosphatidylcholine (PC), sphingomyelin (SM), lysophosphatidylcholine (LPC) and phosphatidylglycerol (PG). It was observed that PG had the highest proportion at most points relative to other PLs and was the predominant component of PLs (30%-56%). Evolution of individual rate was followed during stored at 20°C and 40°C with or without lithothamne400®, respectively. [less ▲]

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See detailSurvival of Freeze-dried Leuconostoc mesenteroides and Lactobacillus plantarum Related to Their Cellular Fatty Acids Composition during Storage
Coulibaly, Ibourahema ULg; Yao, Amenan Anastasie ULg; Lognay, Georges ULg et al

in Applied Biochemistry and Biotechnology (2009), 157(1), 70-84

Lactic acid bacteria strains Lactobacillus plantarum CWBI-B534 and Leuconostoc ssp. mesenteroïdes (L. mesenteroïdes) Kenya MRog2 were produced in bioreactor, concentrated, with or without cryoprotectants ... [more ▼]

Lactic acid bacteria strains Lactobacillus plantarum CWBI-B534 and Leuconostoc ssp. mesenteroïdes (L. mesenteroïdes) Kenya MRog2 were produced in bioreactor, concentrated, with or without cryoprotectants. In general, viable population did not change significantly after freeze-drying (p>0.05). In most cases, viable population for cells added with cryoprotectants was significantly lower than those without (p<0.05). Cellular fatty acids (CFAs) from the two strains in this study were analyzed before and after freeze-drying. Six CFAs were identified, namely, palmitic (C16:0), palmitoleic (C16:1), stearic (C18:0), oleic (C18:1), linoleic (C18:2), and linolenic (C18:3) acids were identified. Four of them, C16:0, C16:1, C18:0, and C18:1, make up more than 94% or 93% of the fatty acids in L. mesenteroides and L. plantarum, respectively, with another one, namely, C18:3, making a smaller (on average 5–6%, respectively) contribution. The C18:2 contributed very small percentages (on average≤1%) to the total in each strain. C16:0 had the highest proportion at most points relative to other fatty acids. Moisture content and water activity (a w) increased significantly during the storage period. It was observed that C16:1/C16:0, C18:0/C16:0 and C18:1/C16:0 ratios for freeze-dried L. mesenteroides or L. plantarum, with or without cryoprotectants, did not change significantly during the storage period. According to the packaging mode and storage temperatures, C18:2/C16:0 and C18:3/C16:0 ratios for freeze-dried L. mesenteroides and L. plantarum with or without cryoprotectants decreased as the storage time increased. However, a higher C18:2/C16:0 or C18:3/C16:0 ratio for L. mesenteroides and L. plantarum was noted in the freeze-dried powder held at 4 °C or under vacuum and in dark than at 20 °C or in the presence of oxygen and light [less ▲]

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See detailProduction of freeze-dried lactic acid bacteria starter culture for cassava fermentation into gari.
Yao, Amenan Anastasie ULg; Dortu, Carine; Egounlety, Moutairu et al

in African Journal of Biotechnology (2009), 8(19), 4996-5004

Sixteen lactic acid bacteria, eight Lactobacillus plantarum, three L. pentosus, 2 Weissella paramesenteroides, two L. fermemtum and one Leuconostoc mesenteroides ssp. mesenteroides were previously ... [more ▼]

Sixteen lactic acid bacteria, eight Lactobacillus plantarum, three L. pentosus, 2 Weissella paramesenteroides, two L. fermemtum and one Leuconostoc mesenteroides ssp. mesenteroides were previously isolated from cassava fermentation and selected on the basis of their biochemical properties with a view to selecting appropriate starter cultures during cassava fermentation for gari production. In this study, the potential of these pre-selected strains as suitable freeze-dried cultures was evaluated. Their ability to tolerate the freeze-drying process was assessed by dehydration in a glycerol solution of increasing concentration, followed by staining with two fluorescent markers: rhodamine 123 and propydium iodide. Twelve strains that recovered more than 50% of their population value after visualisation on an epi-fluorescent microscope were produced in a bioreactor and freeze-dried. The technological characteristics identified after the freeze-drying process, were a high cell concentration or high survival rate. The ability of the freeze-dried strains to recover their acidification activity was evaluated through the determination of the pH, titratable acidity (% lactic acid/g Dry Weight) and cell count over 24 h on MRS broth. Ultimately, the strains L. plantarum VE36, G2/25, L. fermentum G2/10 and W. paramesenteroides LC11 were selected to be developed as freeze-dried starter cultures for gari production. [less ▲]

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See detailEffect of protective compounds on the survival, electrolyte leakage and lipid degradation of freeze-dried Weissella paramesenteroides LC11 during storage.
Yao, Amenan Anastasie ULg; Wathelet, Bernard ULg; Thonart, Philippe ULg

in Journal of Microbiology and Biotechnology (2009), 19(8), 810-817

The effect of cryoprotectants (maltodextrin+glycerol) and cryoprotectants+antioxidant [ascorbic acid and/or butylated hydroxytoluene (BHT)] mixtures on the survival, electrolyte leakage, and lipid ... [more ▼]

The effect of cryoprotectants (maltodextrin+glycerol) and cryoprotectants+antioxidant [ascorbic acid and/or butylated hydroxytoluene (BHT)] mixtures on the survival, electrolyte leakage, and lipid degradation of freeze-dried Weissella paramesenteroides LC11 during storage was investigated and compared with that of the control (cells without additives) over a 90-day storage period at 4 or 20 degrees in glass tubes with water activity (a(w)) of 0.23. The survival, electrolyte leakage, and lipid degradation were evaluated through colony counts, electrical conductivity, and thiobarbituric acid reactive substances (TBARS) content, respectively. The fatty acids composition was determined by gas chromatography, in both the total lipid extract and the polar lipid fraction, and compared with that of the control after the 90-day storage period. As the storage proceeded, increases in leakage value and TBARS content, as well as a decrease in viability, were observed. After 90 days of storage, the major fatty acids found in both the total lipid extract and the polar lipid fraction were palmitic (16:0), palmitoleic (16:1), stearic (18:0), oleic (18:1), linoleic (18:2), and linolenic (18:3) acids. The survival, leakage value, TBARS content and 18:2/16:0 or 18:3/16:0 ratio were the greatest for the protected strain held at 4 degrees . Cells with the cryoprotectants+BHT mixture showed the highest percentage of survival and 18:2/16:0 or 18:3/16:0 ratio in both lipid extracts, as well as the lowest leakage value and TBARS content after the 90-day storage period. Drying cells with the cryoprotectants+BHT mixture considerably slowed down polar lipid degradation and loss of membrane integrity, resulting in improved viability during storage. [less ▲]

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See detailImpact of polyunsaturated fatty acid degradation on survival and acidification activity of freeze-dried Weissella paramesenteroides LC11 during storage
Yao, Amenan Anastasie ULg; Coulibaly, Ibourahema ULg; Lognay, Georges ULg et al

in Applied Microbiology & Biotechnology (2008), 79(6), 1045-1052

Abstract The impact of polyunsaturated fatty acid (PUFA) degradation on the survival and acidification activity of freeze-dried Weissella paramesenteroides LC11 was investigated over 90-days storage at 4 ... [more ▼]

Abstract The impact of polyunsaturated fatty acid (PUFA) degradation on the survival and acidification activity of freeze-dried Weissella paramesenteroides LC11 was investigated over 90-days storage at 4 °C or 20 °C in vacuumsealed aluminium foil or glass tubes with two water activities (aw=0.11 or 0.23). Colony counts, acidification activity (% lactic acid/g), linoleic/palmitic (18:2/16:0) or linolenic/palmitic (18:3/16:0) ratio by gas chromatography and 18:2 or 18:3 oxylipins by reversed phase-high performance liquid chromatography were determined. The viable cells, acidification activity and 18:2/16:0 or 18:3/ 16:0 ratio decreased as the storage time increased. The survival, acidification activity and 18:2/16:0 or 18:3/16:0 ratio were greatest for the freeze-dried strain held in vacuum-sealed aluminium foil at 4 °C. The 18:2/16:0 or 18:3/16:0 ratio decrease was correlated with the accumulation of 18:2 or 18:3 oxylipins during storage in glass tubes. Hydroperoxy PUFAs, hydroxy PUFAs, divinyl ether PUFAs and oxo PUFAs were the main oxylipins identified. A large decrease in the 18:2/16:0 or 18:3/16:0 ratio and a rapid accumulation of oxylipins during storage might be enough to cause high cell death and loss of metabolic activity. These results provide further experimental support for the hypothesis that lipid oxidation and survival or activity of freeze-dried bacteria might be related. [less ▲]

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See detailSurvival Rate Analysis of Freeze-Dried Lactic Acid Bacteria Using the Arrhenius and Z-Value Models
Yao, Amenan Anastasie ULg; Bera, François ULg; Franz, C. et al

in Journal of Food Protection (2008), 71(2), 431-4

The survival rate of five freeze-dried bacteria species, Lactobacillus plantarum, Lactobacillus pentosus, Weisella paramesenteroides, Leuconostoc mesenteroides, and Lactobacillus fermentum, was described ... [more ▼]

The survival rate of five freeze-dried bacteria species, Lactobacillus plantarum, Lactobacillus pentosus, Weisella paramesenteroides, Leuconostoc mesenteroides, and Lactobacillus fermentum, was described in terms of reaction rate constants (D or k) and temperature sensitivity of rate constants (z or Ea). The freeze-dried strains were stored under vacuum at 55, 37, and 4 degrees C for 168 h, 17 days, and 2 months, respectively. D-values decreased and k increased with an increase of the storage temperature. Neither the z-value nor the inactivation energy (Ea) of the reaction was significantly different (P > 0.05) for all the strains, suggesting that thermal inactivation of the freeze-dried lactic acid bacteria may occur by the same mechanism. Therefore, it was possible to compare rate constants of survival for the freeze-dried strains studied. [less ▲]

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