The gastrointestinal (GI) tract is crucial for food digestion and nutrient absorption in humans. However, the GI tract is usually challenged with oxidative stress that can be induced by various factors, such as exogenous pathogenic microorganisms and dietary alterations. As a part of gut microbiota, Lactobacillus spp. play an important role in modulating oxidative stress in cells and tissues, especially in the GI tract. Oxidative stress is linked with excessive reactive oxygen species (ROS) that can be formed by a few enzymes, such as nicotinamide adenine dinucleotide phosphate (NADPH) oxidases (NOXs). The redox mechanisms of Lactobacillus spp. may contribute to the downregulation of these ROS-forming enzymes. In addition, nuclear factor erythroid 2 (NFE2)-related factor 2 (Nrf-2) and nuclear factor kappa B (NF-κB) are two common transcription factors, through which Lactobacillus spp. modulate oxidative stress as well. As oxidative stress is closely associated with inflammation and certain diseases, Lactobacillus spp. could potentially be applied for early treatment and amelioration of these diseases, either individually or together with prebiotics. However, further research is required for revealing their mechanisms of action as well as their extensive application in the future.

Traditional booths where sensory evaluation usually takes place are highly controlled and therefore have limited ecological validity. Since virtual reality (VR) is substantially interactive and engaging, it has the potential to be applied in sensory science. In this preliminary study, three chocolate types (milk, white, and dark) were evaluated under three contextual settings, including sensory booths (control) and two VR environments (360-degree videos using VR headsets: (i) a pleasant sightseeing tour, and (ii) a live music concert). Untrained participants (n = 67) were asked to rate their liking and the intensity of different chocolate attributes based on the 9-point hedonic scale and just-about-right-scale (JAR). Emotions were evaluated using the check-all-that-apply (CATA) method. Results showed that there were no significant effects of context type on the tasting experience; however, there were significant effects of chocolate type. Milk and white chocolates were preferred over dark chocolate irrespective of the context type. Additionally, more positive emotions were elicited for the dark chocolate in the “virtual live concert” environment. Dark chocolate under the other two environments was associated with negative emotional terms, such as “bored” and “worried.” In terms of more reliable and ecologically valid sensory responses, further research is needed to match suitable VR environments to different chocolate types.

Lactobacillus acidophilus ATCC 4356 (LA), a key probiotic in the human gut microbiota, offers several health benefits. While dietary bioactive compounds are known to influence gut microbiota, their specific mechanisms remain unclear. This study investigated how certain dietary bioactive compounds impact LA gene expression and metabolism. Results showed each compound produces unique transcriptional, metabolic, proteomic, and epigenetic profiles in LA. Notably, dietary compounds altered the epigenetic landscape through N4-methylcytosine (4mC) modification, a relatively underexplored form of methyl modification that may play a role in regulating gene transcription. For instance, genistein treatment up-regulated 76 genes and the down-regulated 130 genes in LA. A gene involved in mucus-binding proteins, crucial for bacterial adhesion, was up-regulated 38-fold, likely due to 4mC modifications. Additionally, the gene coding for the melibiose operon regulatory protein increased 78-fold, enhancing melibiose (a prebiotic) production with genistein, but only 1.1-fold with sodium butyrate. This study highlights the potential of dietary compounds for microbial metabolic engineering, offering a non-GMO method for modulating bacterial performance and other biotechnology applications.

It has been demonstrated that short-term stress can enhance cellular responses and promote longevity, whereas long-term stress shortens lifespan. Understanding the relationship between short-term and long-term stress could offer new insights into comprehending and modulating age-related diseases. In this study, we investigate this relationship using transcriptomic and metabolomic analyses in the yeast model system ( Saccharomyces cerevisiae ). We employed three metabolic treatments: firstly, treating yeast cells with threshold levels of benzoic acid for 24 hours (Short-term [ST] Stressed Cells); secondly, treating yeast cells with threshold levels of benzoic acid for 500 hours, with sub-culturing every 24 hours (Long-term [LT] Stressed Cells); and thirdly, allowing the long-term stressed cells to grow for 16 hours without any benzoic acid (Recovered Cells). Here, we propose that aging is an evolutionarily conserved cellular adaptation mechanism in response to long-term stress exposure. Under short-term stressed conditions, prominent lifespan-extending metabolites such as trehalose and metabolites linked to tumor suppression in humans, such as 5’-methylthioadenosine, were overexpressed. In contrast, LT Stressed Cells activated genes such as those responsible for epigenetic regulatory enzymes that govern the aging process, and secondary stress response genes, such as heat shock proteins (HSPs) which are associated with adaptation to cell damage but also often associated with aged cells. Chronological lifespan experiments showed that LT stressed cells lived a shorter lifespan compared to ST Stressed Cells. This suggests that the markers of aging (eg. HSPs, certain epigenetic regulators) are expressed in response to long-term stress to enable cell survival but have the long-term effect of reducing lifespan. In support of this hypothesis, we also show that genes exclusively activated in ST Stressed Cells are conserved solely in eukaryotes, while those significantly expressed in LT Stressed Cells (aging related) exhibit high conservation across all domains of life, with a majority having originated from bacteria hinting at the potential evolutionary benefit of aging.

This study investigates the impact of epigenetic modification on Saccharomyces cerevisiae using sodium butyrate (SB), a histone deacetylase inhibitor (HDACi), to enhance sensory characteristics in beer fermentation. Epigenetics offers a non-GMO approach to modifying gene expression, with potential for cost-effective strain development in brewing. A commercial ale yeast was cultured under different SB exposure regimes and used to ferment wort. Sensory evaluation was conducted with untrained participants, alongside GC-MS and enzymatic assays for ethanol, glycerol, and residual sugars. While no significant differences were found in ethanol production or smoothness and creaminess—likely due to uniform wort composition—flavor and taste scores varied between treatments. Notably, yeast pre-treated with SB but fermented without additional SB (1G W/O) received the highest flavor acceptability. Treatments involving SB during fermentation showed reduced sensory scores, likely due to butyric off-notes. Higher alcohol levels remained within acceptable thresholds and were more likely influenced by wort amino acid content than epigenetic modification. Though SB had a limited impact on metabolic pathways, this study highlights the feasibility of using dietary epigenetic modifiers to develop novel yeast strains with improved sensory profiles in beer or other fermented beverages and warrants further investigation with alternative compounds.