Conjugated linoleic acid production by cells and enzyme extract of Lactobacillus delbrueckii ssp. bulgaricus with additions of different fatty acids

Tween 80™-induced changes in fatty acid profile of selected mesophilic lactobacilli

Fatty acid profiles are crucial for the functionality and viability of lactobacilli used in food applications. Tween 80™, a common culture media additive, is known to influence bacterial growth and composition. This study investigated how Tween 80™ supplementation impacts the fatty acid profiles of six mesophilic lactobacilli strains (Lacticaseibacillus spp., Limosilactobacillus spp., Lactiplantibacillus plantarum). Analysis of eleven strains revealed 29 distinct fatty acids. Tween 80™ supplementation significantly altered their fatty acid composition. Notably, there was a shift towards saturated fatty acids and changes within the unsaturated fatty acid profile. While some unsaturated fatty acids decreased, there was a concurrent rise in cyclic derivatives like lactobacillic acid (derived from vaccenic acid) and dihydrosterculic acid (derived from oleic acid). This suggests that despite the presence of Tween 80™ as an oleic acid source, lactobacilli prioritize the synthesis of these cyclic derivatives from precursor unsaturated fatty acids. Myristic acid and dihydrosterculic acid levels varied across strains. Interestingly, palmitic acid content increased, potentially reflecting enhanced incorporation of oleic acid from Tween 80™ into membranes. Conversely, cis-vaccenic acid levels consistently decreased across all strains. The observed fatty acid profiles differed from previous studies, likely due to a combination of factors including strain-specific variations and growth condition differences (media type, temperature, harvesting point). However, this study highlights the consistent impact of Tween 80™ on the fatty acid composition of lactobacilli, regardless of these variations. In conclusion, Tween 80™ significantly alters fatty acid profiles, influencing saturation levels and specific fatty acid proportions. This work reveals key factors, including stimulated synthesis of lactobacillic acid, competition for oleic acid incorporation, and strain-specific responses to myristic and dihydrosterculic acids. The consistent reduction in cis-vaccenic acid and the presence of cyclic derivatives warrant further investigation to elucidate their roles in response to Tween 80™ supplementation.

Non-inhibitory levels of oxygen during cultivation increase freeze-drying stress tolerance in Limosilactobacillus reuteri DSM 17938

The physiological effects of oxygen on Limosilactobacillus reuteri DSM 17938 during cultivation and the ensuing properties of the freeze-dried probiotic product was investigated. On-line flow cytometry and k-means clustering gating was used to follow growth and viability in real time during cultivation. The bacterium tolerated aeration at 500 mL/min, with a growth rate of 0.74 ± 0.13 h^-1 which demonstrated that low levels of oxygen did not influence the growth kinetics of the bacterium. Modulation of the redox metabolism was, however, seen already at non-inhibitory oxygen levels by 1.5-fold higher production of acetate and 1.5-fold lower ethanol production. A significantly higher survival rate in the freeze-dried product was observed for cells cultivated in presence of oxygen compared to absence of oxygen (61.8% ± 2.4% vs. 11.5% ± 4.3%), coinciding with a higher degree of unsaturated fatty acids (UFA:SFA ratio of 10 for air sparged vs. 3.59 for N₂ sparged conditions.). Oxygen also resulted in improved bile tolerance and boosted 5'nucleotidase activity (370 U/L vs. 240 U/L in N₂ sparged conditions) but lower tolerance to acidic conditions compared bacteria grown under complete anaerobic conditions which survived up to 90 min of exposure at pH 2. Overall, our results indicate the controlled supply of oxygen during production may be used as means for probiotic activity optimization of L. reuteri DSM 17938.

Bacterial production of conjugated linoleic and linolenic Acid in foods: a technological challenge

Conjugated linoleic acid (CLA) and conjugated linolenic acid (CLNA) isomers are present in foods derived from ruminants as a result of the respective linoleic acid (LA) and α-linolenic acid (LNA) metabolism by ruminal microorganisms and in animals' tissues. CLA and CLNA have isomer-specific, health-promoting properties, including anticarcinogenic, antiatherogenic, anti-inflammatory, and antidiabetic activity, as well as the ability to reduce body fat. Besides ruminal microorganisms, such as Butyrivibrio fibrisolvens, many food-grade bacteria, such as bifidobacteria, lactic acid bacteria (LAB), and propionibacteria, are able to convert LA and LNA to CLA and CLNA, respectively. Linoleate isomerase activity, responsible for this conversion, is strain-dependent and probably related to the ability of the producer strain to tolerate the toxic effects of LA and LNA. Since natural concentrations of CLA and CLNA in ruminal food products are relatively low to exert their health benefits, food-grade bacteria with linoleate isomerase activity could be used as starter or adjunct cultures to develop functional fermented dairy and meat products with increased levels of CLA and CLNA or included in fermented products as probiotic cultures. However, results obtained so far are below expectations due to technological bottlenecks. More research is needed to assess if bacterial production kinetics can be increased and can match food processing requirements.

Influence of the addition of Lactobacillus acidophilus La-05, Bifidobacterium animalis subsp. lactis Bb-12 and inulin on the technological, physicochemical, microbiological and sensory features of creamy goat cheese

We evaluated the effects of addition of probiotic cultures and inulin on the quality of creamy goat cheese.

Probiotic Characteristics of Conjugated Linoleic Acid Producing Bacteria

The aim of this study was to select CLA producing bacteria from fermented diary products and human faeces, then evaluate their resistance to simulated gastrointestinal stress and adhesiveness to human intestinal epithelial cells according typically assess methods. Additionally, hydrophobicity, resistance to opportunistic pathogens and phenol ability were analysed. Results showed that three L. paracasei subp. Paracasei (F0721, IN 5.22 and Q9), two Lactobacillus acidophilus (F0221 and M6) and one Lactobacillus plantarum (G14) exert the ability to product conjugated linoleic aicd ranging from 77.21 to 111.59 μg/ml in the presence of 0.5 mg/ml linoleic acid (LA) in MRSc broth under anaerobic conditions at 37°C for 40 h. Strain F0721, IN5.22 and G14 showed higher resistance to gastric acid than other strains at pH 2.0, F0721 and IN5.22 showed higher tolerance ability at pH 3.0. F0221 showed the highest bile salt tolerance than other strains at 0.15%, 0.3% and 0.5% bile concentrations, whereas highest sensitivity to the bile stress was found for IN5.22. F0221, IN5.22 and G14 strains showed the highest levels of adherences (range from 106 to 129 cfu/100 cells), and intestine origin bacteria (F0221, F0721 and IN5.22) exhibited higher hydrophobicity values and resistant to phenol ability as compared to the dairy products.

Growth temperatures and various concentrations of ricinoleic acid affect fatty acid composition in two strains of Hansenula polymorpha

The fatty acid composition of two strains (wild-type and M2 mutant cells of Hansenula polymorpha strain CBS 1976) were studied at different growth temperatures and various concentrations of ricinoleic acid. Two strains of yeast cultured on YEPD medium containing 1, 2, 3 and 8 mM of ricinoleic acid at 25, 30, 37 and 45 degrees C. Lipids were extracted from the yeast culture and the fatty acids esterified with BF3-MeOH. Gas chromatography analysis of total lipids showed that C16:1 (delta7), which has been synthesized in low concentration by WT strain, was found to increase in the M2 mutant. The biotransformation of C16:1 (delta7) found in M2 indicated the presence of dehydroxylation and beta-oxidation systems. An increase in the growth temperature from 25 to 45 degrees C resulted in a decrease in the total unsaturated fatty acids of C16:1, C18:1, C18:2 and C18:3 from 44.0 to 22.1% and 65.0 to 49.3% of the total fatty acids in M2 and wild-type strains, respectively. The differential production of unsaturated fatty acids, especially C16:1, indicated that regulation of unsaturated fatty acid levels, is an important control point in membrane composition in the adaptation of H. polymorpha M2 to diet and temperature.

Ruminal biohydrogenation as affected by tanninsin vitro

The aim of the present work was to study the effects of tannins from carob (CT;Ceratonia siliqua), acacia leaves (AT;Acacia cyanophylla) and quebracho (QT;Schinopsis lorentzii) on ruminal biohydrogenationin vitro.The tannins extracted from CT, AT and QT were incubated for 12 h in glass syringes in cow buffered ruminal fluid (BRF) with hay or hay plus concentrate as a substrate. Within each feed, three concentrations of tannins were used (0·0, 0·6 and 1·0 mg/ml BRF). The branched-chain volatile fatty acids, the branched-chain fatty acids and the microbial protein concentration were reduced (P < 0·05) by tannins. In the tannin-containing fermenters, vaccenic acid was accumulated (+23 %,P < 0·01) while stearic acid was reduced ( − 16 %,P < 0·0005). The concentration of total conjugated linoleic acid (CLA) isomers in the BRF was not affected by tannins. The assay on linoleic acid isomerase (LA-I) showed that the enzyme activity (nmol CLA produced/min per mg protein) was unaffected by the inclusion of tannins in the fermenters. However, the CLA produced by LA-I (nmol/ml per min) was lower in the presence of tannins. These results suggest that tannins reduce ruminal biohydrogenation through the inhibition of the activity of ruminal micro-organisms.