Implications of modifying membrane fatty acid composition on membrane oxidation,integrity, and storage viability of freeze‐dried probiotic,Lactobacillus acidophilus La‐5

The aim of this study was to investigate the effect of altering the fatty acid profile of the lipid membrane on storage survival of freeze‐dried probiotic, Lactobacillus acidophilus La‐5, as well as study the membrane integrity and lipid oxidation. The fatty acid composition of the lipid membrane of L. acidophilus La‐5 was significantly different upon growth in MRS (containing Tween 80, an oleic acid source), or in MRS with Tween 20 (containing C12:0 and C14:0), linoleic, or linolenic acid supplemented. Bacteria grown in MRS showed the highest storage survival rates. No indications of loss of membrane integrity could be found, and membrane integrity could therefore not be connected with loss of viability. Survival of bacteria grown with linoleic or linolenic acid was more negatively affected by the presence of oxygen, than bacteria grown in MRS or with Tween 20 supplemented. A small, but significant, loss of linolenic acid during storage could be identified, and an increase of volatile secondary oxidation products during storage was found for bacteria grown in MRS, or with linoleic, or linolenic acid supplemented, but not for bacteria grown with Tween 20. Overall, the results indicate that lipid oxidation and loss of membrane integrity are not the only or most important detrimental reactions which can occur during storage. By altering the fatty acid composition, it was also found that properties of oleic acid gave rise to more robust bacteria than more saturated or unsaturated fatty acids did. © 2015 American Institute of Chemical Engineers Biotechnol. Prog., 31:799–807, 2015     

Association analyses of single nucleotide polymorphisms in bovine stearoyl-CoA desaturase and fatty acid synthase genes with fatty acid composition in commercial cross-bred beef steers

Two previously reported non‐synonymous coding single nucleotide polymorphisms (SNPs) of bovine stearoyl‐CoA desaturase (delta‐9‐desaturase) (SCD) (c.878C>T) and fatty acid synthase (FASN) (g:17924A>G) were assessed for their associations with 72 individual and 12 groups of fatty acids in brisket adipose tissue of 223 Canadian commercial cross‐bred beef steers. It was found that the ‘CC’ genotype of the SCD SNP was significantly associated with lower concentrations of saturated fatty acids (SFA) including 10:0, 14:0 and 20:0, higher concentrations of monounsaturated fatty acids including 9c‐14:1, 12c‐16:1 and 13c‐18:1, higher concentrations of polyunsaturated fatty acids (PUFA) including 9c,15c‐18:2, 10c,12c‐18:2, 11c,13t‐18:2 and 12c,14t‐18:2, but lower concentrations of other PUFA of 9c,13t/8t,12c and 20:2n‐6 (P < 0.05). The ‘AA’ genotype of the FASN SNP was significantly associated with higher concentrations of SFAs of 10:0, 12:0, 13:0, 14:0 and 15:0, lower concentrations of unsaturated fatty acids of 9c‐18:1 and 20:3n‐6, and higher concentrations of unsaturated fatty acids of 9c‐14:1 and 12c‐16:1 (P < 0.05). Significant epistatic effects between the SCD and FASN SNP genotypes were also found for several fatty acids including 10:0, 23:0, 6t/7t/8t‐18:1, 12t‐18:1, 13t/14t‐18:1, 16t‐18:1, total trans18:1 and 9c,13t/8t,12c‐18:2 (P < 0.05). These results further suggest that SCD and FASN are strong candidate genes influencing fatty acid composition in beef cattle.     

Whole‐genome association study for fatty acid composition of oleic acid in Japanese Black cattle

Fatty acid composition, especially oleic acid (C18:1), plays an important role in the eating quality of meat in Japanese Black cattle. Therefore, the objective of this study was to identify loci associated with C18:1 in the intramuscular fat of the trapezius muscles in Japanese Black cattle using the Illumina BovineSNP50 BeadChip whole genome single nucleotide polymorphism (SNP) assay. We also evaluated the relationship between C18:1 and three fatty acid synthesis genes, fatty acid synthase (FASN), stearoyl‐CoA desaturase and sterol regulatory element‐binding protein‐1. In this experiment, we applied a mixed model and Genomic Control approach using selective genotyping to perform a genome‐wide association study. A total of 160 animals (80 animals with higher values and 80 animals with lower values), selected from 3356 animals based on corrected phenotype, were genotyped using the Illumina BovineSNP50 BeadChip and three fatty acid synthesis genes, and the quality of these SNPs was assessed. In this study, a total of 38 955 SNPs, which included SNPs in the three fatty acid synthesis genes, were used, and the estimated inflation factor was 1.06. In the studied population, a total of 32 SNPs, including the FASN gene, had significant effects, and in particular 30 SNPs of all significant SNPs were located between 49 and 55 Mbp on chromosome 19. This study is one of the first genome‐wide association studies for fatty acid composition in a cattle population using the recently released Illumina BovineSNP50 BeadChip.     

Effect of benzyl viologen on the phospholipid fatty acid composition and some properties in hepatic microsomal membrane of rats

The effect of benzyl viologen (a stimulator of free radical production in cells) on lipid composition, fluidity and enzymes involved in both polyunsaturated fatty acid biosynthesis and cholesterol metabolism was studied in liver microsomal membrane of adult rats. In viologen-treated animals, a significant decrease in the levels of free cholesterol and cholesteryl esters, accompanied to a decrease at the free cholesterol/phospholipid ratio, were observed. The levels of 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase and acyl-coenzyme A : cholesterol acyltransferase (ACAT) were also lower in viologen-treated rats than in controls. Linoleic and arachidonic acids were both severely lower while docosatetraenoic, docosapentaenoic and docosahexaenoic acids were significantly higher as compared with controls. Furthermore, a decrease in monounsaturated/saturated ratio was found. In addition, the treatment evoked a depression in the fatty acid desaturation complex, with a diminish of ⁹, ⁹, and ⁵ desaturase activities in microsomal membrane.It was concluded that changes in phospholipid microsomal fatty acid and cholesterol content could be directly responsible for changes in membrane fluidity and function, and that extensive yield of docosahexaenoic acid may serve to maintain the physical characteristics of particular domains against oxidative stress caused by benzyl viologen treatment.