Orally delivered probiotics must survive transit through harsh environments during gastrointestinal (GI) digestion and be delivered and released into the target site. The aim of this work was to evaluate the survivability and delivery of gel-encapsulated Lactobacillus rhamnosus GG (LGG) to the colon. New hybrid symbiotic beads alginate/prebiotic pullulan/probiotic LGG were obtained by the extrusion method. The average size of the developed beads was 3401 µm (wet), 921 µm (dry) and the bacterial titer was 10⁹ CFU/g. The morphology of the beads was studied by a scanning electron microscope, demonstrating the structure of the bacterial cellulose shell and loading with probiotics. For the first time, we propose adding an enzymatic extract of feces to an artificial colon fluid, which mimics the total hydrolytic activity of the intestinal microbiota. The beads can be digested by fecalase with cellulase activity, indicating intestinal release. The encapsulation of LGG significantly enhanced their viability under simulated GI conditions. However, the beads, in combination with the prebiotic, provided greater protection of bacteria, enhancing their survival and even increasing cell numbers in the capsules. These data suggest the promising prospects of coencapsulation as an innovative delivery method based on the inclusion of probiotic bacteria in a symbiotic matrix.

1. Background: Iodine is a broad-spectrum antimicrobial disinfectant for topical application. Recent studies have shown promising results on the applicability of an iodine-containing complex, FS-1, against antibiotic-resistant pathogens. It was hypothesized that the antimicrobial activity of iodine-containing complexes may be modulated by the organic moiety of the complex, i.e., amino acids. 2. Methods: Gene regulation and metabolic alterations were studied in two model multidrug-resistant microorganisms, Staphylococcus aureus ATCC BAA-39, and Escherichia coli ATCC BAA-196, treated with three complexes containing iodine and three different amino acids: glycine, L-alanine, and L-isoleucine. The bacterial cultures were exposed to sub-lethal concentrations of the complexes in the lagging and logarithmic growth phases. Gene regulation was studied by total RNA sequencing and differential gene expression analysis. 3. Results: The central metabolism of the treated bacteria was affected. An analysis of the regulation of genes involved in stress responses suggested the disruption of cell wall integrity, DNA damage, and oxidative stress in the treated bacteria. 4. Conclusions: Previous studies showed that the application of iodine-containing complexes, such as FS-1, serves as a supplement to common antibiotics and can be a promising way to combat antibiotic-resistant pathogens. Current results shed light on possible mechanisms of this action by disrupting the cell wall barriers and imposing oxidative stress. It was also found that the effect of the complexes on metabolic pathways varied in the tested microorganisms depending on the organic moiety of the complexes and the growth phase when the complexes had been applied.

Objectives: The global rise in multidrug resistance underscores the urgent need for the development of novel and effective antimicrobial agents. Semi-organic iodine-containing complexes, owing to their unique properties, low likelihood of resistance development, and stability under various conditions, represent a promising avenue for the design of new therapeutic strategies. This study describes the synthesis of semi-organic iodine-containing complexes and the in vitro evaluation of their impact on antibiotic susceptibility modulation in the multidrug-resistant pathogenic microorganisms S. aureus and E. coli. Methods: The physicochemical properties of the semiorganic compounds were characterized using UV-Vis spectroscopy, potentiometric, and titrimetric methods. Evaluation of antimicrobial activity was obtained according to CLSI protocols. The impact of semiorganic compounds on the in vitro susceptibility of MDR strains was evaluated by the disk diffusion method. Results: This study evaluated the effects of iodine-containing complexes KC-270 and KC-271 on the antibiotic susceptibility of Staphylococcus aureus BAA-39 and Escherichia coli BAA-196. The most pronounced effect was observed with KC-270 applied during the lag phase, which enhanced the activity of several antibiotics and, in some cases, restored susceptibility. KC-271 exhibited a weaker and more limited impact. The findings suggest that KC-270 has potential as a modulator of antibiotic susceptibility, particularly when administered at early stages of bacterial growth. Conclusions: The results support the ability of amino acid-based iodine coordination compounds to influence the antibiotic susceptibility of pathogenic bacteria, highlighting their potential as adjuvant agents to improve the effectiveness of current antimicrobial therapies. However, although changes in susceptibility were detected, neither compound fully eliminated resistance in the multidrug-resistant strains, indicating the necessity for further research into their mechanisms of action and possible synergistic interactions with antibiotics.