Metabolic services of intestinal microbiota of swine: metabolism of carbohydrates and bile salts

Vertebrate animals are holobionts and their physiology and metabolism are influenced by their commensal microbiota. Gut microbiota and their metabolites play a key role in the host defense against pathogenic microorganisms, shape the immune system, and impact the resistance to chronic disease. The metabolic activity of intestinal microbiota contributes significantly to the conversion of diet components to molecules that can be absorbed and metabolized by the host. The metabolic capacity of the intestinal microbiota by far exceeds the metabolic capacity of the hosts. Collectively, gut microbes support the digestion of the major nutrients, i.e. carbohydrates, proteins and lipids, and impact uptake and conversion of micronutrients, e.g. phenolic compounds and minerals. This chapter provides an overview on the metabolism of carbohydrates and bile salts by pig microbiota.

The human bile salt sodium deoxycholate induces metabolic and cell envelope changes in Salmonella Typhi leading to bile resistance

Introduction. Salmonella enterica serovar Typhi (S. Typhi) is the etiological agent of typhoid fever. To establish an infection in the human host, this pathogen must survive the presence of bile salts in the gut and gallbladder. Hypothesis. S. Typhi uses multiple genetic elements to resist the presence of human bile. Aims. To determine the genetic elements that S. Typhi utilizes to tolerate the human bile salt sodium deoxycholate. Methodology. A collection of S. Typhi mutant strains was evaluated for their ability to growth in the presence of sodium deoxycholate and ox-bile. Additionally, transcriptomic and proteomic responses elicited by sodium deoxycholate on S. Typhi cultures were also analysed. Results. Multiple transcriptional factors and some of their dependent genes involved in central metabolism, as well as in cell envelope, are required for deoxycholate resistance. Conclusion. These findings suggest that metabolic adaptation to bile is focused on enhancing energy production to sustain synthesis of cell envelope components exposed to damage by bile salts.

Dietary Fiber and Dyslipidemia

Fibers are abundantly found in vegetables, fruit, beans, cereals, seeds, and tubers. Beans and seeds, alongside prevailing as both of the fiber sources, are the sources of vegetable protein as well. Whereas tubers are a carbohydrate source, which people deem as a staple food. Fiber intake in diets, particularly soluble fibers, has the ability to produce gel in the intestines, inhibiting glucose and cholesterol absorption. Dietary fibers have the ability to bind bile salts in the digestive tract, and disturbed bile reabsorption will stimulate bile synthesis in the liver. Dyslipidemia has a significant role in systemic responses and inflammation in adipose tissues. Inflammation can increase intestinal permeability and adipose tissues. Dyslipidemic management is carried out by altering lifestyles, intervening in suitable diets to reduce LDL levels, and increasing HDL levels. The degree of compliance with diet interventions is seminal to ensure successful dyslipidemic management.

Effects of 405 ± 5-nm LED Illumination on Environmental Stress Tolerance of Salmonella Typhimurium in Sliced Beef

Salmonella Typhimurium is a widely distributed foodborne pathogen and is tolerant of various environmental conditions. It can cause intestinal fever, gastroenteritis and bacteremia. The aim of this research was to explore the effect of illumination with 405 nm light-emitting diodes (LEDs) on the resistance of S. Typhimurium to environmental stress. Beef slices contaminated with S. Typhimurium were illuminated by 405 nm LEDs (18.9 ± 1.4 mW/cm2) for 8 h at 4 °C; controls were incubated in darkness at 7 °C. Then, the illuminated or non-illuminated (control) cells were exposed to thermal stress (50, 55, 60 or 65 °C); oxidative stress (0.01% H2O2 [v/v]); acid stress (simulated gastric fluid [SGF] at pH 2 or 3); or bile salts (1%, 2%, or 3% [w/v]). S. Typhimurium treated by 405 nm LED irradiation showed decreased resistance to thermal stress, osmotic pressure, oxidation, SGF and bile salts. The transcription of eight environmental tolerance-related genes were downregulated by the illumination. Our findings suggest the potential of applying 405 nm LED-illumination technology in the control of pathogens in food processing, production and storage, and in decreasing infection and disease related to S. Typhimurium.

Structural and Dynamic Determinants of Molecular Recognition in Bile Acid-Binding Proteins

Disorders in bile acid transport and metabolism have been related to a number of metabolic disease states, atherosclerosis, type-II diabetes, and cancer. Bile acid-binding proteins (BABPs), a subfamily of intracellular lipid-binding proteins (iLBPs), have a key role in the cellular trafficking and metabolic targeting of bile salts. Within the family of iLBPs, BABPs exhibit unique binding properties including positive binding cooperativity and site-selectivity, which in different tissues and organisms appears to be tailored to the local bile salt pool. Structural and biophysical studies of the past two decades have shed light on the mechanism of bile salt binding at the atomic level, providing us with a mechanistic picture of ligand entry and release, and the communication between the binding sites. In this review, we discuss the emerging view of bile salt recognition in intestinal- and liver-BABPs, with examples from both mammalian and non-mammalian species. The structural and dynamic determinants of the BABP-bile–salt interaction reviewed herein set the basis for the design and development of drug candidates targeting the transcellular traffic of bile salts in enterocytes and hepatocytes.

Probiotic Characterization And Safety Assessment of Lactococcus Lactis Subsp. Lactis R7 Isolated From Ricotta Cheese

The aim of this study was to identify and characterize in vitro Lactococcus lactis R7 isolated from commercial ricotta cheese. The results from phenotypic characterization demonstrated that L. lactis R7 had growth potential in a wide temperature range (15 °C and 45 °C), ability to tolerate high osmotic concentrations (sodium chloride 4.0 %), ability to growth in acidic and alkaline condition (pH 2.0 and 9.6), and ability to sugar fermentation (glucose, maltose and ribose). The findings confirm that L. lactis R7 belong to the genus Lactococcus. The results from molecular identification by 16S RNA identified the isolate as Lactococcus lactis subsp. lactis R7. The phenotypic characteristics combined with the molecular identification, indicate that the isolate R7 belongs to the lactis subspecies. The isolate L. lactis R7 was tolerant to acidity and bile salts. In the intestinal tract, cell concentrations were higher than 7.98 log CFU.mL-1 in the presence and absence of bile salts. L. lactis R7 showed antioxidant and inhibitory capacity for lipid peroxidation. It also demonstrated capacity for self-aggregation (25.8%), coaggregation (18.3%) and hydrophobicity (11.1%). The antagonist activity of the isolate was greater against Staphylococcus aureus (12.2 mm), when compared to Escherichia coli (11.1 mm) and Salmonella enteritidis (9.5 mm). In the MTT assays, L. lactis R7 did not show cytotoxicity to VERO cells at the evaluated concentrations. In conclusion, L. lactis R7 isolated from ricotta cheese presented probiotic characteristics and compatible safety aspects for use as a food technology culture.

Characterization of the Probiotic Potential of Lactic Acid Bacteria Isolated from Kimchi, Yogurt, and Baby Feces in Hong Kong and Their Performance in Soymilk Fermentation

Background: There are several potential healthy or nutritional benefits from the use of lactic acid bacteria (LAB) in foods. This study aimed to characterize the LAB isolates from kimchi, yogurt, and baby feces in the Hong Kong area and evaluate their performance in fermented soymilk, which allowed us to assess their potential use in future experiments. Methods: General characteristics including tolerance to acid, NaCl, bile salts and phenol, antimicrobial activity to various pathogens, and adhesive ability to Caco-2 cells were evaluated using 18 LAB in this study. To further demonstrate the influence of such isolates in soymilk fermentation, we measured viability by plating and noting changes in pH, amino acid content, aglyconic isoflavones content and antioxidant capacities in vitro, such as scavenging ability, and iron chelating ability. Results: In this study, various LAB isolates belonging to Lactobacillusrhamnosus, Lactobacillus sakei, Lactiplantibacillus plantarum, andLeuconostocmesenteroides isolated in Hong Kong were evaluated. L. plantarum isolates R7, AC12, and AC14.1, and L. rhamnosus AC1 showed higher tolerance to acid, NaCl, bile salts, and phenol as compared to the other isolates tested. L. plantarum isolates AC12, AC13 and AC14.1, and L. rhamnosus AC1 harbored strong antimicrobial activity. L. plantarum isolates R7, AC12, AC13 and AC14.1, and L. paracasei isolates R6 and R8 showed higher adhesive ability than the other tested isolates. In soymilk, the viable numbers of L. paracasei R5, L. plantarum R7, L. rhamnosus AC1, L. sakei AC2, and Leu. mesenteroides AC5 were much higher than the other tested isolates after 48 h of fermentation. The pH value measuring the lactic acid level in soymilk fermented by L. plantarum AC14.1 was the lowest in comparison to those in soymilk fermented by other isolates. In addition, the levels of free amino acids and isoflavones in the aglycone forms of L. rhamnosus AC1-fermented soymilk were the highest. L. rhamnosus AC1-fermented soymilk also showed the highest antioxidant potential, including DPPH scavenging ability and iron chelating ability. Conclusions: In general, L. plantarum isolates R7 and AC14.1 and L. rhamnosus AC1 exhibited higher tolerance to challenging conditions as compared to the other isolates. Moreover, L. rhamnosus AC1 exhibited superior performance in soymilk fermentation and potential as a starter and probiotic culture.

POTENSI KOMBUCHA DAUN TEH (Camellia sinensis) DAN DAUN KOPI ROBUSTA (Coffea robusta) SEBAGAI MINUMAN PROBIOTIK

Kombucha is a plant-based fermented beverage that contains probiotic bacteria such as lactic acid bacteria (LAB). This research was conducted to prove the potential of probiotics in LAB isolates of kombucha tea leaves and robusta coffee leaves with various concentrations. This research used a completely randomized design (CRD). The variables tested were the measurement of total lactic acid bacteria, total acid, and probiotic characterization of LAB isolates (LAB resistance to low pH and bile salts, and antibacterial activity test). The results were analyzed and discussed using ANOVA with a significance level of P < 0.05 only for total acid and descriptive analysis on microbiological response. The best probiotic potency was selected using the multiple attribute method. The results showed that LAB isolates from kombucha tea leaves and robusta coffee leaves with various concentrations had resistance to pH 2 and pH 3, resistance to bile salts 3%, and antibacterial activity against Staphylococcus aureus and Escherichia coli bacteria. The LAB isolate of kombucha robusta coffee leaves at a concentration of 0.6% has the best probiotic potential. Kombucha merupakan minuman fermentasi berbasis tanaman yang mengandung bakteri probiotik seperti bakteri asam laktat (BAL). Penelitian ini dilakukan untuk membuktikan potensi probiotik pada isolat BAL kombucha daun teh dan daun kopi robusta dengan berbagai konsentrasi. Penelitian laboratorium menggunakan rancangan acak lengkap (RAL). Variabel yang diuji adalah pengukuran total bakteri asam laktat, total asam, ketahanan BAL terhadap pH rendah dan garam empedu, serta uji aktivitas antibakteri. Hasil penelitian dianalisa dan dibahas menggunakan ANOVA dengan signifikansi P < 0.05 hanya untuk total asam dan analisa deskriptif pada respons mikrobiologis. Potensi probiotik terbaik dipilih menggunakan metode multiple attribute. Hasil penelitian menunjukkan bahwa isolat BAL dari kombucha daun teh dan daun kopi robusta dengan berbagai konsentrasi memiliki ketahanan terhadap pH 2 dan pH 3, ketahanan terhadap garam empedu 3%, serta aktivitas antibakteri terhadap bakteri Staphylococcus aureus dan Escherichia coli. Isolat BAL kombucha daun kopi robusta pada konsentrasi 0,6% mempunyai potensi probiotik terbaik.

Importance of Bile Composition for Diagnosis of Biliary Obstructions

Determination of the cause of a biliary obstruction is often inconclusive from serum analysis alone without further clinical tests. To this end, serum markers as well as the composition of bile of 74 patients with biliary obstructions were determined to improve the diagnoses. The samples were collected from the patients during an endoscopic retrograde cholangiopancreatography (ERCP). The concentration of eight bile salts, specifically sodium cholate, sodium glycocholate, sodium taurocholate, sodium glycodeoxycholate, sodium chenodeoxycholate, sodium glycochenodeoxycholate, sodium taurodeoxycholate, and sodium taurochenodeoxycholate as well as bile cholesterol were determined by HPLC-MS. Serum alanine aminotransferase (ALT), aspartate transaminase (AST), and bilirubin were measured before the ERCP. The aim was to determine a diagnostic factor and gain insights into the influence of serum bilirubin as well as bile salts on diseases. Ratios of conjugated/unconjugated, primary/secondary, and taurine/glycine conjugated bile salts were determined to facilitate the comparison to literature data. Receiver operating characteristic (ROC) curves were determined, and the cut-off values were calculated by determining the point closest to (0,1). It was found that serum bilirubin was a good indicator of the type of biliary obstruction; it was able to differentiate between benign obstructions such as choledocholithiasis (at the concentration of >11 µmol/L) and malignant changes such as pancreatic neoplasms or cholangiocarcinoma (at the concentration of >59 µmol/L). In addition, it was shown that conjugated/unconjugated bile salts confirm the presence of an obstruction. With lower levels of conjugated/unconjugated bile salts the possibility for inflammation and, thus, neoplasms increase.

Potential of Lactic Acid Bacteria From Tape and Jember Tempeh as a Probiotic Candidate

Probiotics are microbes in fermented foods that have beneficial effects on health. Microbes that act as probiotics are lactic acid bacteria (LAB) that can produce metabolites such as lactic acid, hydrogen peroxide, and bacteriocins. This study aimed to obtain lactic acid bacterial isolates from tape and tempeh, and to test the potential of LAB as a probiotic candidate by activity test as an antidiarrhea and its resistance to gastric pH and bile salts. The fermentation products used as a source of LAB isolates are tempeh sumber mas merk, and yellow cassava tape, sari madu merk from Jember. The results of the first stage regarding the isolation of LAB using GYP media showed that there were 2 LAB isolates (TaJ.14 and TaJ.15) from the tape and 4 LAB isolates (TeJ.18, TeJ.22, TeJ.24, and TeJ.25) from tempeh. The results of the antidiarrheal test using the disc diffusion method (oxoid) showed that TaJ.14 and TaJ.15 isolates were able to inhibit Bacillus subtilis, Escherichia coli, and Shigella dysentriae, while TeJ.18, TeJ.22, TeJ.24, TeJ.25, and Lactobacillus casei (control) was only able to inhibit B. subtilis and E. coli. The results of LAB resistance to gastric pH showed that the TeJ.25 isolate had the highest percentage of pH 3 and 2.5 resistance (51.13 and 33.03%) compared to other isolates and controls. LAB resistance test results against bile salts (oxgal) showed that the TeJ.22 isolate had the highest percentage of resistance (75.10%) compared to other isolates although was still higher in control (75.99%).