Exploiting Apical Sodium-Dependent Bile Acid Transporter (ASBT)-Mediated Endocytosis with Multi-Functional Deoxycholic Acid Grafted Alginate Amide Nanoparticles as an Oral Insulin Delivery System.

OBJECTIVE: Oral administration of insulin is a potential candidate for managing diabetes. However, it is obstructed by the gastrointestinal tract barriers resulting in negligible oral bioavailability. METHODS: This investigation presents a novel nanocarrier platform designed to address these challenges. In this regard, the process involved amination of sodium alginate by ethylene diamine, followed by its conjugation with deoxycholic acid. RESULTS: The resulting DCA@Alg@INS nanocarrier revealed a significantly high insulin loading content of 63.6 ± 1.03% and encapsulation efficiency of 87.6 ± 3.84%, with a particle size of 206 nm and zeta potentials of -3 mV. In vitro studies showed sustained and pH-dependent release profiles of insulin from nanoparticles. In vitro cellular studies, confocal laser scanning microscopy and flow cytometry analysis confirmed the successful attachment and internalization of DCA@Alg@INS nanoparticles in Caco-2 cells. Furthermore, the DCA@Alg@INS demonstrated a superior capacity for cellular uptake and permeability coefficient relative to the insulin solution, exhibiting sixfold and 4.94-fold enhancement, respectively. According to the uptake mechanism studies, the results indicated that DCA@Alg@INS was mostly transported through an energy-dependent active pathway since the uptake of DCA@Alg@INS by cells was significantly reduced in the presence of NaN3 by ~ 92% and at a low temperature of 4°C by ~ 94%. CONCLUSIONS: Given the significance of administering insulin through oral route, deoxycholic acid-modified alginate nanoparticles present a viable option to surmount various obstacles presented by the gastrointestinal.

Antifungal activity of protective cultures against the yogurt drink-specific spoilage yeasts.

Fungal agents emerged as post-pasteurization contamination are responsible for the spoilage in yogurt drink. In this work, the antifungal effects of some lactic acid bacteria (LAB) on the spoilage yeasts isolated from yogurt drink (Doogh) were evaluated. First, the microbial growth in the yogurt drink samples during the storage time was investigated, and the isolated microorganisms were identified using biochemical methods and sequencing of the specific amplicons. Yeasts (3-7 log CFU ml-1 ) were found to be the most abundant microorganisms (specific spoilage organisms) in several samples. Using the amplification technique of rDNA by ITS1 and ITS4 primers, the dominant yeasts were identified as Pichia kudriavzevii, Kluyveromyces marxianus, and Candida parapsilosis. Then, the antimicrobial activity of 37 strains of LAB against the isolated yeasts was studied using broth microdilution. Eventually, the strains of Lacticplantibacillus plantarum (245, 24, P6, and P7), Lactiplantibacillus pentosus (20), and Levilactobacillus brevis (30) exhibited significant antifungal activity. In the most effective impacts, lag times of C. parapsilosis, K. marxianus, and P. kudriavzevii were increased by almost 12-19 h, 12-19 h, and 2-6 h, respectively, while the area under the growth curve for these yeasts was reduced to lower than 40%, near 16%, and approximately 67%, in the order given. Overall, these bacteria showed high potential as the substituents for chemical preservatives in yogurt drinks. PRACTICAL APPLICATION: Spoilage yeasts were isolated from yogurt drink and identified by molecular method. Isolated yeasts belonged to Pichia, Kluyveromyces, and Candida genera. Inhibitory effects of 37 strains were evaluated against the spoilage yeasts. Cell-free supernatant was used against the isolated fungi in microdilution method. Several LAB strains showed a significant antimicrobial activity.

Semi-continuous production of xanthan in biofilm reactor using Xanthomonas campestris.

Semi-continuous production of xanthan gum using self-immobilized Xanthomonas campestris cells in biofilm reactors was studied. Fermentation was carried out using two different designs of biofilm reactor equipped with a) stainless-steel support (SSS) and b) polyethylene support (PES). Fermentation was performed in three cycles with refreshing the media at the beginning of each: cycle 1, 0-27 h; cycle 2, 27-54 h; and cycle 3, 54-78.5 h. Results showed that the glucose consumption and the pH reduction in the PES biofilm reactor was faster compared to the SSS biofilm reactor. Scanning electron microscopy showed that the SSS was capable to immobilize more cells during the growth of X. campestris. The maximum concentration of xanthan gum in the SSS biofilm reactor obtained after 27 h (3.47 ± 0.71 g/L), while the maximum concentration of xanthan in the PES biofilm reactor obtained after 78.5 h (3.21 ± 0.68 g/L). Thermal stability analysis of xanthan using differential scanning calorimetry showed the presence of two fractures attributed to dehydration and degradation of polymer. The thermogram represented both endothermal and exothermal behaviour of xanthan polymer. Furthermore, the functional groups and molecular structure of the xanthan produced in this study was evaluated using Fourier transform infrared spectrometry and also proton nuclear magnetic resonance. in addition, the surface tension of (0.2 %, w/v) xanthan gum solution was in a range of 52.16-56.5 mN/m. Rheological analysis of xanthan showed that the G' values were higher than the G″ in all frequencies demonstrating a relatively high elasticity of the produced xanthan gum.

Antibacterial Effect of Essential Oils against Spoilage Bacteria from Vacuum-Packed Cooked Cured Sausages.

Nonfermented sausages, which have a pH of around 6.0, a low salt concentration, and high moisture with a water activity higher than 0.95, are highly perishable. In this study, culture-dependent techniques and 16S rDNA approaches were used to identify the presumptive spoilage lactic acid bacteria (LAB) in sliced vacuum-packed cooked sausage during storage at 4°C. The antibacterial properties of essential oils (EOs) from the medicinal plants Carum carvi, Cinnamomum zeylanicum, Curcuma longa, Citrus medica, and Eugenia caryophyllata against isolated LAB were also investigated. A total of 106 colonies were obtained on de Man Rogosa Sharpe medium after storage of sausages samples, and 16 isolates were identified from conventional morphological analysis of the bacterial populations. DNA extraction and 16S rDNA analysis indicated that Lactobacillus curvatus, Weissella viridescens, Leuconostoc mesenteroides, Enterococcus faecium, Lactobacillus reuteri, Lactobacillus dextrinicus, Lactobacillus sakei, and Pediococcus dextrinicus were the main spoilage LAB. The antibacterial properties of EOs against isolated LAB were indicated by inhibition zones on culture plates of 7.8 to 31 mm, depending on the susceptibility of the tested LAB strain. The MICs and MBCs of five EOs were determined. The most effective EO against the LAB was C. zeylanicum followed by C. carvi and C. medica, and the least effective EO was C. longa. The EO from C. zeylanicum had the highest antimicrobial activity (lowest MICs) against LAB, with EO MICs of 4.66 to 5.33 µL/mL. The most susceptible isolate was L. mesenteroides, with a MIC of 4.66 µL/mL for the C. zeylanicum EO. These data indicate that the EO from C. zeylanicum could be used as a natural preservative for vacuum-packed emulsion-type sausage.