Linoleic Acid Triggered a Metabolomic Stress Condition in Three Species of Bifidobacteria Characterized by Different Conjugated Linoleic Acid-Producing Abilities

Abstract

Abundant conjugated linoleic acid (CLA) producers exist among Bifidobacterium species. This CLA production is related to the mitigation of LA toxicity. However, there is still a lack of information on the metabolic response underlying this detoxification strategy. In this study, six bifidobacteria strains belonging to three different species were used to characterize growth and CLA accumulation in the presence of LA. A combination of non-targeted metabolomics techniques and biochemical indicators were used to explore metabolic profile changes in response to LA and the expression of important factors driving CLA production in Bifidobacterium species. The results suggested that free LA had growth inhibitory effects on bifidobacteria, resulting in a global metabolic stress response that caused metabolic reprogramming on all tested strains and promoted malondialdehyde production, inducing a redox imbalance. In particular, a strong decrease in reduced glutathione level was observed in Bifidobacterium breve CCFM683 [log 2 (FC) = −3.29]. Furthermore, LA-induced oxidative stress is an important factor driving high CLA production in certain strains.

Computational Analysis and Heterologous Expression of BBI-like Proteins from Food-Grade Bifidobacterium Species Reveal Possibly a Key Factor in Conjugated Linoleic Acid Bioconversion

“…coli catalyzes the conversion of LA to CLA, and the product includes only c 9, t 11-CLA. In contrast, during the conversion of LA to CLA in Bifidobacterium , the proportion of c 9, t 11-CLA decreases as the product accumulates and is accompanied by an increase in the proportion of t 9, t 11-CLA . Uncharacterized enzymes may be responsible for the conversion of c 9, t 11- to t 9, and t 11-CLA in this process. , …”

“…22 Uncharacterized enzymes may be responsible for the conversion of c9, t11-to t9, and t11-CLA in this process. 22,52 In conclusion, BBI-like proteins from four Bif idobacterium species possess c9, t11-CLA production activity; sequence variation is a factor that deserves in-depth consideration and contributes to the clarification of the species-level productive traits of bifidobacterial CLA-producing strains. Moreover, such findings provide a worthwhile scientific basis for the production and development of functional foods with selected CLA isomers and related dietary supplements using BBI-like proteins.…”

“…pseudocatenulatum, and B. dentium, were previously isolated from fecal samples . These strains were selected on the basis that they contained the bbi homologue of the gene encoding linoleic acid isomerase and had a clear difference in CLA conversion capacity.…”

Heterologous expression of a novel linoleic acid isomerase BBI, and effect of fusion tags on its performance

“…In addition, the process of CLA production by Bifidobacterium using BBI is considered as a defense mechanism in response to LA stress ( Mei et al, 2021 ). Hence, a reasonable hypothesis is that the BBI active site is located in the N-terminal portion of the exposed extracellular ( Fig.…”

“…However, the procedure still faces many challenges. First, CLA-production by B. breve occurs during the growth phase of the strain, and the culture conditions of B. breve CLA-producers are harsh and costly ( Mei et al, 2021 ); second, the bioconversion of LA to CLA by B. breve involves a stress-defence reaction, making it difficult to increase the substrate concentration further ( Senizza et al, 2020 ). Moreover, due to the complex transmembrane structure of BBI (with nine transmembrane regions), only low levels of expression may occur in the original strain, making it difficult to obtain large amounts of BBI directly from its natural host.…”