A GC-MS Based Metabolic Profiling of Probiotic Lactic Acid Bacteria Isolated from Traditional Food Products

Gas chromatography-mass spectrometry analysis of metabolites in finger millet and Bambara groundnut as affected by traditional and novel food processing

Metabolite profiling is an analytical technique used to assess metabolites in complex biological samples. This technique allows for the identification of both targeted and untargeted metabolites. In this study, the effect of traditional (fermentation and malting) and novel processing (ultrasonication) on the metabolites of finger millet (FM) and Bambara groundnut (BGN) flour was investigated using gas chromatography-mass spectrometry. Various metabolite classes, including amino acids, alcohol, aldehyde, organic acid, ester, fatty acids, glycoside, and sugar, were identified in FM and BGN flours. The adopted processing techniques impacted metabolite composition, as evidenced by substantial variations in volatile compound levels and metabolite composition among the FM and BGN samples before and after traditional and novel processing. Important health-promoting compounds, such as oleic acid, linoelaidic acid, and linoleic acid, were identified at their highest levels in fermented FM and BGN flours. The results obtained from this study offer an important context for monitoring and regulating the metabolite composition of FM and BGN flours under traditional and novel processing. PRACTICAL APPLICATION: Fermentation, malting, and ultrasonication induced desirable changes in some health-promoting compounds of finger millet and Bambara groundnut flours. The food and pharmaceutical industries could benefit from these traditional- and novel-modified flours as they could be used as improved food sources with health benefits.

Malva neglecta seed polysaccharide mucilage coating enriched by the Lactobacillus brevis TD4 postbiotics: A promising strategy to promote the shelf life of fresh beef

The need for bioactive-incorporated biodegradable packaging products is growing due to the desire to achieve food goods that have a longer shelf life and enhanced safety. The current study set out to create an edible coating using Malva neglecta seed polysaccharide mucilage (MNSM) containing Lactobacillus brevis TD4-derived postbiotics (PLB), and assess how well the PLB-MNSM edible coating preserved beef slices over a 12-day period of refrigeration. PLB was rich in fatty acids, organic heteropolycyclic compounds, monoterpene and cyclohexanol derivative, prenol lipids, ester compounds, and alpha-CH2-containing aldehyde with significant antimicrobial and antioxidant activities. By adding it to the edible coating at 0, 5, 10, and 15 % v/v, it successfully prevented the proliferation of microbial agents (total viable count, psychrotrophic count, Staphylococcus aureus, Escherichia coli, total coliform bacteria count, and fungi) as well as the oxidation of lipids (thiobarbituric and peroxide values) in beef samples. The samples' pH value, hardness, and moisture content were all more successfully sustained when PLB preparation was applied to the coating solution (P < 0.05). The edible coating consisting of PLB effectively maintained the meat color (L*, a*, b*) and sensory properties. Additionally, the bioactive edible coating comprised of MNSM and PLB, specifically MNSM-15 % PLB, significantly prevented the quality deterioration of beef samples and prolonged the shelf-life of the meat to over 12 days. The outcomes indicated that the MNSM-PLB edible coating has the capacity to be utilized as an antibacterial and antioxidant-rich packing material, hence enhancing the shelf life of meat-based goods.

Metagenomics and metagenome-assembled genomes mining of health benefits in jalebi batter, a naturally fermented cereal-based food of India

Jalebi is one of the oldest Indian traditional fermented wheat-based confectioneries. Since jalebi is prepared by natural fermentation, diverse microbial community is expected to play bio-functional activities. Due to limited studies, information on microbial community structure in jalebi is unknown. Hence, the present study is aimed to profile the microbial community in jalebi by shotgun metagenomics and also to predict putative probiotic and functional genes by metagenome-assembled genome (MAG). Bacteria were the most abundant domain (91.91%) under which Bacillota was the most abundant phylum (82%). The most abundant species was Lapidilactobacillus dextrinicus followed by several species of lactic acid bacteria, acetic acid bacteria including few yeasts. Lap. dextrinicus was also significantly abundant in jalebi when compared to similar fermented wheat-based sourdough. Additionally, Lap. bayanensis, Pediococcus stilesii, and yeast- Candida glabrata, Gluconobacter japonicus, Pichia kudriavzevii, Wickerhamomyces anomalus were only detected in jalebi, which are not detected in sourdough. Few viruses and archaea were detected with < 1 % abundance. In silico screening of genes from the abundant species was mined using both KEGG and EggNOG database for putative health beneficial attributes. Circular genomes of five high-quality MAGs, identified as Lapidilactobacillus dextrinicus, Enterococcus hirae, Pediococcus stilesii, Acetobacter indonesiensis and Acetobacter cibinongensis, were constructed separately and putative genes were mapped and annotated. The CRISPR/Cas gene clusters in the genomes of four MAGs except Acetobacter cibinongensis were detected. MAGs also showed several secondary metabolites. Since, the identified MAGs have different putative genes for bio-functional properties, this may pave the way to selectively culture the uncultivated putative microbes for jalebi production. We believe this is the first report on metagenomic and MAGs of jalebi.

Biological Characterization and Metabolic Variations among Cell-Free Supernatants Produced by Selected Plant-Based Lactic Acid Bacteria

The aim of this research was to assess the antibacterial and antioxidant properties as well as the variation in metabolites of the cell-free supernatant (CFS) produced by lactic acid bacteria (LAB) from local plants: Lactiplantibacillus plantarum ngue16, L. plantarum ng10, Enterococcus durans w3, and Levilactobacillus brevis w6. The tested strains exhibited inhibitory effects against pathogens, including Bacillus cereus, B. subtilis, Cronobacter sakazakii, Escherichia coli, Salmonella Typhimurium, and Staphylococcus aureus using the agar spot assay and well diffusion method. The CFS from all four strains displayed antibacterial activity against these pathogens with minimum inhibitory concentration (MIC) values ranging from 3.12 to 12.5 mg/mL and minimal bactericidal concentration (MBC) values ranging from 6.25 to 25.0 mg/mL. Moreover, the CFS demonstrated resilience within specific pH (3-8) and temperature (60-100 °C) ranges and lost its activity when treated with enzymes, such as Proteinase K and pepsin. Furthermore, the CFS exhibited antioxidant properties as evidenced by their ability to inhibit the formation of two radicals (1,1-diphenyl-2-picrylhydrazyl (DPPH) and ferric reducing antioxidant power (FRAP) compared to the negative control, De Man, Rogosa, and Sharpe (MRS) broth. The use of proton-based nuclear magnetic resonance (¹H-NMR) spectroscopy revealed the presence and quantification of 48 metabolites in both the CFS and MRS broths. Principal Component Analysis (PCA) effectively differentiated between CFS and MRS broth by identifying the specific metabolites responsible for the observed differences. The partial least squares (PLS) model demonstrated a significant correlation between the metabolites in the LAB supernatant and the tested antibacterial and antioxidant activities. Notably, anserine, GABA, acetic acid, lactic acid, uracil, uridine, propylene glycol, isopropanol, serine, histidine, and indol-3-lactate were identified as the compounds contributing the most to the highest antibacterial and antioxidant activities in the supernatant. These findings suggest that the LAB strains investigated have the potential to be utilized in the production of functional foods and the development of pharmaceutical products.

Chemically Defined Lactobacillus plantarum Cell-Free Metabolites Demonstrate Cytoprotection in HepG2 Cells through Nrf2-Dependent Mechanism

Centering around the concept that metabolites from the gut commensals can exert metabolic health benefits along the gut-liver axis, we tested whether the cell-free global metabolome of probiotic bacteria can exert hepatoprotective benefits against H₂O₂-induced oxidative stress. Cell-free global metabolites of Lactobacillus plantarum (LPM) were isolated and untargeted metabolomics was performed. The free radical scavenging potentials of LPM were measured. The cytoprotective effects of LPM were tested on HepG2 cells. A total of 66 diverse metabolites were identified in LPM, among which saturated fatty acids, amino acids and dicarboxylic acids were highly enriched. LPM attenuated cell damage, lipid peroxidation and the levels of intracellular cytoprotective enzymes in H₂O₂-treated cells. LPM also attenuated H₂O₂-induced increased expressions of TNF-α and IL-6. However, the cytoprotective effects of LPM were diminished in cells that were pretreated with a pharmacological inhibitor of Nrf2. Our data collectively indicate that LPM can significantly attenuate oxidative damage to HepG2 cells. However, the cytoprotective effects of LPM likely depend on an Nrf2-dependent mechanism.

Anti-inflammatory and Immunostimulant Therapy with Lactobacillus fermentum and Lactobacillus plantarum in COVID-19: A Literature Review

Inflammatory diseases are diseases characterized by inflammatory symptoms. Acute inflammatory disease can cause dysregulation of the inflammatory immune response, thereby inhibiting the development of protective immunity against infection. Among the acute inflammatory disease is COVID-19. The initial viral infection causes the antigen-presenting cells to detect the virus through a phagocytosis mechanism in the form of macrophage and dendritic cells. Lactobacillus fermentum and L. plantarum are gram-positive bacteria potentially serving as immunomodulators caused by inflammation and immune system response. Short-chain fatty acids (SCFA) produced by Lactobacillus can induce immune response through tolerogenic dendritic cells. This probiotic bacterium can induce the production of different cytokines or chemokines. Following the results of in vitro and in vivo tests, L. fermentum and L. plantarum can induce IL-10 release to activate regulatory T-cell and inhibit tumor necrosis factor-α (TNF-α) binding activity of nuclear factor kappa B (NF-κB). Literature review showed that dysregulation of inflammatory immune response disorders due to inflammatory disease could be treated using probiotic bacteria L. fermentum and L. plantarum. Therefore, it is necessary to conduct further studies on the potential of indigenous Indonesian strains of these two bacteria as anti-inflammatory and immunostimulants.

Genome In Silico and In Vitro Analysis of the Probiotic Properties of a Bacterial Endophyte, Bacillus Paranthracis Strain MHSD3

Spore-forming Bacillus species are gaining interest in human health recently, due to their ability to withstand the harsh environment of the gastrointestinal tract. The present study explores probiotic features of Bacillus paranthracis strain MHSD3 through genomic analysis and in vitro probiotic assays. The draft genome of strain MHSD3 contained genes associated with tolerance to gastrointestinal stress and adhesion. Cluster genes responsible for the synthesis of antimicrobial non-ribosomal peptide synthetases, bacteriocins, and linear azole-containing peptides were identified. Additionally, strain MHSD3 was able to survive in an acidic environment, had the tolerance to bile salt, and exhibited the capability to tolerate gastric juices. Moreover, the isolate was found to possess strong cell surface traits such as high auto-aggregation and hydrophobicity indices of 79 and 54%, respectively. Gas chromatography-mass spectrometry analysis showed that the strain produced secondary metabolites such as amino acids, phenolic compounds, and organic acid, known to exert health-promoting properties, including the improvement of gastrointestinal tract health.

GC-MS Metabolomics and Antifungal Characteristics of Autochthonous Lactobacillus Strains

Lactobacillus strains with the potential of protecting fresh dairy products from spoilage were studied. Metabolism and antifungal activity of different L. plantarum, L. brevis, and L. sakei strains, isolated from Sardinian dairy and meat products, were assessed. The metabolite fingerprint of each strain was obtained by GC-MS and data submitted to multivariate statistical analysis. The discriminant analysis correctly classified samples to the Lactobacillus species and indicated that, with respect to the other species, L. plantarum had higher levels of organic acids, while L. brevis and L. sakei showed higher levels of sugars than L. plantarum. Partial Least Square (PLS) regression correlated the GC-MS metabolites to the antifungal activity (p < 0.05) of Lactobacillus strains and indicated that organic acids and oleamide are positively related with this ability. Some of the metabolites identified in this study have been reported to possess health promoting proprieties. These overall results suggest that the GC-MS-based metabolomic approach is a useful tool for the characterization of Lactobacillus strains as biopreservatives.