Search Results (29)

Antifungal composite beads were prepared using a methylcellulose, alginate, and ethanol solution with the ionic gelation method and ethanol beads (E). A total of 1.0 mL of clove essential oil (CEO) and 1.0 g of vanillin were added to provide an antifungal effect against Aspergillus flavus and Rhizopus stolonifera. Four bead formulations were prepared: ethanol beads (E), ethanol beads containing CEO (EC), ethanol beads containing vanillin (EV), and ethanol beads containing vanillin and CEO (EVC). Ethanol beads were transparent and spherical, whereas those containing CEO or vanillin were spherical and opaque, with diameters ranging from 2.1 to 2.4 mm. The surface and pores in the polymer matrix were investigated in relation to the encapsulation and release of antifungal agents. The bursting release of ethanol and CEO occurred on the first day. Antifungal assays on potato dextrose agar against Aspergillus flavus and Rhizopus stolonifera showed that beads containing CEO (EC and EVC) provided superior inhibition, particularly at a dosage of 1.0 g. In butter cake preservation tests, packaging the butter cake with a sachet containing 1.0 g of EC or EVC beads can extend the shelf life by two days, delaying visible mold growth from day 5 to day 7 compared to the control. Full article

Encapsulation techniques play a crucial role in enhancing the stability and viability of probiotics in functional foods. This study investigates the efficacy of calcium–alginate encapsulation, combined with hydrocolloids such as carrageenan, agar, and gelatin, in improving the survival of Lactobacillus rhamnosus GG (LGG) and stabilizing the total phenolic content (TPC) in fermented black goji berry beverages. The results revealed that 1.5% alginate encapsulation, combined with 1% carrageenan, agar, or gelatin and 5% calcium, significantly enhanced the LGG viability and increased the TPC content in the fermented black goji berry beads when compared to calcium–alginate encapsulation alone. Fourier Transform Infrared Spectroscopy (FTIR) confirmed the successful incorporation and interaction of hydrocolloids within the encapsulation matrix. Among the formulations, calcium–alginate–gelatin beads exhibited the highest LGG survival rates after simulated gastric and intestinal digestion. Notably, calcium–alginate beads containing carrageenan preserved LGG viability during simulated gastric and intestinal conditions when co-digested with all tested milk types (high carbohydrate, high protein, and high fat). Co-ingestion with these milk types further improved TPC retention in all bead formulations, as the macronutrients in milk provided protective effects, stabilizing the encapsulated polyphenols and minimizing their degradation during simulated gastric and intestinal digestion. This study highlights the potential of calcium–alginate encapsulation, integrated with hydrocolloids such as carrageenan, agar, or gelatin, to improve probiotic viability and polyphenol stability, offering promising applications for enhancing the functional properties of non-dairy fermented beverages. Full article

Methyl gallate (MG), a natural phenolic compound, exhibits in vitro synergistic activity with amoxicillin (Amox) against methicillin-resistant Staphylococcus aureus (MRSA), a global health concern. This study developed electrospun nanofibers incorporating MG and Amox into a poly(vinyl alcohol) (PVA)/chitosan (CS) blend to target both methicillin-susceptible S. aureus (MSSA) and MRSA. The formulation was optimized, and the impact of acetic acid on antibacterial activity was evaluated using agar disc diffusion. The final formulation was fabricated and characterized using SEM, FTIR, DSC, swelling, and release behavior analyses to understand its antibacterial efficacy. Results revealed that acetic acid eliminated antibacterial activity, but MG (64 mg/mL) and Amox (2.5 mg/mL) were successfully incorporated into a PVA/CS solution prepared with deionized water. The resulting nanofiber mats featured nanoscale fibers (126 ± 45 nm) with and micron-oval beads. Despite the in vitro synergism, the MG/Amox/PVA/CS mats showed no significant improvement over MG or Amox alone against MRSA, likely due to their physicochemical properties. FTIR and DSC results confirmed molecular interactions between the active compounds and the polymer matrix, which may cause a minimal swelling and low drug release at 24 h. This study offers insights into the potential of MG/Amox-loaded nanofibers for anti-MRSA material development. Full article

This review details the extraction, characterization and utilization of seaweed-derived biopolymers for future packaging applications. The review is contextualized within the broader scope of the challenge of plastic pollution and the current urgent need for more sustainable packaging materials. Macroalgae (or seaweed) has been highlighted as a promising source of biopolymers, most commonly sodium alginate, agar and carrageenan, for reasons such as a rapid growth rate and decreased environmental impact when compared with terrestrial plant life. Extraction methods detailed include traditional solvent-based extraction and more sustainable developments such as ultrasound-assisted extraction, microwave-assisted extraction and bead milling. This review additionally presents the characterization techniques most pertinent in determining the applicability of these biopolymers in packaging applications. Properties of key importance to the development of sustainable packaging materials such as thermal properties, mechanical strength, barrier properties and biodegradability are highlighted in comparison to conventional petroleum-based plastics. This review concludes by realistically identifying the challenges faced by implementing seaweed-based biopolymers into packaging structures, such as cost-effectiveness, scalability and performance while suggesting future directions to mitigate these issues and improve the commercial viability of these materials for the packaging industry. Full article

Co-infection with Pseudomonas (Pa) and Aspergillus (Af) commonly occurs in the airways of immune-compromised patients or in cystic fibrosis and frequently results in more severe outcomes than mono-infection. We affixed both pathogens to agar beads, separately (Af beads, Pa beads) or on the same bead (AfPa beads) and infected immunocompetent mice, an in vivo Af-Pa interaction model. Endotracheal administration was superior to intranasal, allowing larger beads to be administered resulting in longer lung residence. The CFU of the Af beads, diameter 150–250 µm, were detectable for ≤21 days. Af-bead-infected mice cleared the Af infection more than mice infected with AfPa beads, but Af clearance was the same with a combination of beads (Af beads + Pa beads). Pa-infected mice had more Pa clearance in the presence of Af than with Pa beads alone. In vitro studies supported our conclusion that the close proximity of Af and Pa (on AfPa beads) was disadvantageous for Af, whereas a larger distance (Af + Pa beads) was not. We demonstrated that the interaction between Pseudomonas and Aspergillus during co-infection can be studied in immunocompetent mice. The mutual inhibition of Af and Pa in vivo appears to be dependent on their proximity. We review the literature relating to animal models of infection with Af, Pa, or both. Full article

Background: Multispecies biofilm orthopedic infections are more challenging to treat than mono-species infections. In this in-vitro study, we aimed to determine if a multispecies biofilm, consisting of Gram positive and negative species with different antibiotic susceptibilities could be treated more effectively using high purity antibiotic-loaded calcium sulfate beads (HP-ALCSB) containing vancomycin (VAN) and tobramycin (TOB) in combination than alone. Methods: Three sets of species pairs from bioluminescent strains of Pseudomonas aeruginosa (PA) and Staphylococcus aureus (SA) and clinical isolates, Enterococcus faecalis (EF) and Enterobacter cloacae were screened for compatibility. PA + EF developed intermixed biofilms with similar cell concentrations and so were grown on 316L stainless steel coupons for 72 h or as 24 h agar lawn biofilms and then treated with HP-ALCSBs with single or combination antibiotics and assessed by viable count or bioluminescence and light imaging to distinguish each species. Replica plating was used to assess viability. Results: The VAN + TOB bead significantly reduced the PA + EF biofilm CFU and reduced the concentration of surviving antibiotic tolerant variants by 50% compared to single antibiotics. Conclusions: The combination of Gram-negative and positive targeted antibiotics released from HP-ALCSBs may be more effective in treating multispecies biofilms than monotherapy alone. Full article

Pseudomonas aeruginosa (P. aeruginosa) is an opportunistic pathogen and the leading cause of infection in patients with cystic fibrosis (CF). The ability of P. aeruginosa to evade host responses and develop into chronic infection causes significant morbidity and mortality. Several mouse models have been developed to study chronic respiratory infections induced by P. aeruginosa, with the bead agar model being the most widely used. However, this model has several limitations, including the requirement for surgical procedures and high mortality rates. Herein, we describe novel and adapted biologically relevant models of chronic lung infection caused by P. aeruginosa. Three methods are described: a clinical isolate infection model, utilising isolates obtained from patients with CF; an incomplete antibiotic clearance model, leading to bacterial bounce-back; and the establishment of chronic infection; and an adapted water bottle chronic infection model. These models circumvent the requirement for a surgical procedure and, importantly, can be induced with clinical isolates of P. aeruginosa and in wild-type mice. We also demonstrate successful induction of chronic infection in the transgenic βENaC murine model of CF. We envisage that the models described will facilitate the investigations of host and microbial factors, and the efficacy of novel antimicrobials, during chronic P. aeruginosa respiratory infections. Full article

Salmonella enterica is a causative pathogen of Salmonellosis, a zoonosis causing global disease and financial losses every year. Pigs may be carriers of Salmonella and contribute to the spread to humans and food products. Salmonella may persist as biofilms. Biofilms are bacterial aggregates embedded in a self-produced matrix and are known to withstand disinfectants. We studied the effect of glutaraldehyde and peracetic acid, two active substances frequently used in disinfectant formulations in the pig industry, on representative biofilm-residing wild-type Salmonella collected from pig housings in the United Kingdom (UK). We screened biofilm production of strains using the microtiter plate (MTP) assay and Congo Red Coomassie Blue (CRCB) agar method. Previously published stainless-steel coupon (SSCA), polyvinylchloride coupon (PCA), and glass bead (GBA) assays were used for disinfection studies. The mean reduction in the tested wild-type strains met the criterion of ≥4 log₁₀ CFU at a disinfectant concentration of 0.05% with SSCA and GBA, and 0.005% with PCA for peracetic acid, along with 0.5% for glutaraldehyde with all three assays on the mean. At these concentrations, both tested disinfectants are suitable for disinfection of pig housings against Salmonella. When evaluating the efficacy of disinfectants, biofilms should be included, as higher disinfectant concentrations are necessary compared to planktonic bacteria. Full article

We demonstrate that Blautia coccoides JCM1395^T has the potential to be used for tumor-targeted live bacterial therapeutics. Prior to studying its in vivo biodistribution, a sample preparation method for reliable quantitative analysis of bacteria in biological tissues was required. Gram-positive bacteria have a thick outer layer of peptidoglycans, which hindered the extraction of 16S rRNA genes for colony PCR. We developed the following method to solve the issue; the method we developed is as follows. The homogenates of the isolated tissue were seeded on agar medium, and bacteria were isolated as colonies. Each colony was heat-treated, crushed with glass beads, and further treated with restriction enzymes to cleave DNAs for colony PCR. With this method, Blautia coccoides JCM1395^T and Bacteroides vulgatus JCM5826^T were individually detected from tumors in mice intravenously receiving their mixture. Since this method is very simple and reproducible, and does not involve any genetic modification, it can be applied to exploring a wide range of bacterial species. We especially demonstrate that Blautia coccoides JCM1395^T efficiently proliferate in tumors when intravenously injected into tumor-bearing mice. Furthermore, these bacteria showed minimal innate immunological responses, i.e., elevated serum tumor necrosis factor α and interleukin-6, similar to Bifidobacterium sp., which was previously studied as a therapeutic agent with a small immunostimulating effect. Full article

This review examines the immobilization of A. pullulans cells for production of the fungal polysaccharide pullulan. Pullulan is a water-soluble gum that exists structurally as a glucan consisting primarily of maltotriose units, which has a variety of food, non-food and biomedical applications. Cells can be immobilized by carrier-binding or entrapment techniques. The number of studies utilizing carrier-binding as a method to immobilize A. pullulans cells appears to outnumber the investigations using cell entrapment. A variety of solid supports, including polyurethane foam, sponge, diatomaceous earth, ion-exchanger, zeolite and plastic composite, have been employed to immobilize pullulan-producing A. pullulans cells. The most effective solid support that was used to adsorb the fungal cells was polyurethane foam which produced polysaccharide after 18 cycles of use. To entrap pullulan-producing fungal cells, agents such as polyurethane foam, polyvinyl alcohol, calcium alginate, agar, agarose, carrageenan and chitosan were investigated. Polysaccharide production by cells entrapped in polyurethane foam, polyvinyl alcohol or calcium alginate was highest and the immobilized cells could be reutilized for several cycles. It was shown that the pullulan content of the polysaccharide synthesized by cells entrapped in calcium alginate beads was low, which limits the method’s usefulness for pullulan production. Further, many of the entrapped fungal cells synthesized polysaccharide with a low pullulan content. It was concluded that carrier-binding techniques may be more effective than entrapment techniques for A. pullulans cell immobilization, since carrier-binding is less likely to affect the pullulan content of the polysaccharide being synthesized. Full article

Praziquantel (PZQ) provides an effective treatment against monogenean parasitic infestations in finfish. However, its use as an in-feed treatment is challenging due to palatability issues. In this study, five formulations of PZQ beads (1–4 mm) were developed using marine-based polymers, with allicin added as a flavouring agent. All formulations attained PZQ loading rates ≥74% w/w, and the beads were successfully incorporated into fish feed pellets at an active dietary inclusion level of 10 g/kg. When tested for palatability and digestibility in small yellowtail kingfish, the PZQ-loaded beads produced with alginate-chitosan, alginate-Cremophor^® RH40, and agar as carriers resulted in high consumption rates of 99–100% with no digesta or evidence of beads in the gastrointestinal tract (GIT) of fish fed with diets containing either formulation. Two formulations produced using chitosan-based carriers resulted in lower consumption rates of 68–75%, with undigested and partly digested beads found in the fish GIT 3 h post feeding. The PZQ-loaded alginate-chitosan and agar beads also showed good palatability in large (≥2 kg) yellowtail kingfish infected with gill parasites and were efficacious in removing the parasites from the fish, achieving >90% reduction in mean abundance relative to control fish (p < 0.001). The two effective formulations were stable upon storage at ambient temperature for up to 18 months, showing residual drug content >90% compared with baseline levels. Overall, the palatability, efficacy and stability data collected from this study suggest that these two PZQ particulate formulations have potential applications as in-feed anti-parasitic medications for the yellowtail kingfish farming industry. Full article

Cleaning wastewater containing low concentrations of phenolic compounds is a challenging task. In this work, agar–alginate beads impregnated with trihexyltetradecylphosphonium bromide ([P₆₆₆₁₄][Br]) ionic liquid adsorbent were synthesized as a potential adsorbent for such applications. FTIR, TGA, SEM, EDX and PZC studies were performed to characterize and understand the physicochemical properties of the adsorbent. The Fourier transformation infrared spectroscopy (FTIR) study showed that [P₆₆₆₁₄][Br] ionic liquid was effectively incorporated into the agar–alginate structure. TGA and SEM confirmed comparative enhanced thermal stability and porous surface, respectively. Chemical reaction rate-altering parameters, i.e., pH, contact time, initial phenol concentration and temperature, are optimized at highest phenol removal. It was found that the maximum phenol adsorption capacity and highest removal efficiency by the adsorbent occurred at pH 2, initial phenol concentration of 150 mg/L, beads dosage of 6 mg/mL and contact time of 2 h with values of 16.28 mg/g and 65.12%, respectively. The pseudo-second order model fitted the adsorption kinetics well, and the Freundlich isotherm model gave the experimental data the best fit. Analysis of thermodynamic data demonstrated that the adsorption process is fundamentally exothermic in nature, and low temperature favors spontaneity of the chemical reaction. Regeneration studies indicated that the adsorbent can at least be used for four cycles in such applications without any considerable loss in adsorption efficiency. Full article

Whole-cell immobilization by entrapment in natural polymers can be a tool for morphological control and facilitate biomass retention. In this study, the possibility of immobilizing the filamentous fungus Aspergillus oryzae for l-malic acid production was evaluated with the two carbon sources acetate and glucose. A. oryzae conidia were entrapped in alginate, agar, and κ-carrageenan and production was monitored in batch processes in shake flasks and 2.5-L bioreactors. With glucose, the malic acid concentration after 144 h of cultivation using immobilized particles was mostly similar to the control with free biomass. In acetate medium, production with immobilized conidia of A. oryzae in shake flasks was delayed and titers were generally lower compared to cultures with free mycelium. While all immobilization matrices were stable in glucose medium, disintegration of bead material and biomass detachment in acetate medium was observed in later stages of the fermentation. Still, immobilization proved advantageous in bioreactor cultivations with acetate and resulted in increased malic acid titers. This study is the first to evaluate immobilization of A. oryzae for malic acid production and describes the potential but also challenges regarding the application of different matrices in glucose and acetate media. Full article

This study analyzed the thermostability and effect of calcium ions on the enzymatic activity of α-amylase produced by Bacillus licheniformis strain LB04 isolated from Espinazo Hot springs in Nuevo Leon, Mexico. The enzyme was immobilized by entrapment on agar-agarose beads, with an entrapment yield of 19.9%. The identification of the bacteria was carried out using 16s rDNA sequencing. The enzyme was purified through ion exchange chromatography (IEX) in a DEAE-Sephadex column, revealing a protein with a molecular weight of ≈130 kDa. The enzyme was stable at pH 3.0 and heat stable up to 80 °C. However, the optimum conditions were reached at 65 °C and pH 3.0, with a specific activity of 1851.7 U mg⁻¹ ± 1.3. The agar-agarose immobilized α-amylase had a hydrolytic activity nearly 25% higher when compared to the free enzyme. This study provides critical information for the understanding of the enzymatic profile of B. licheniformis strain LB04 and the potential application of the microorganisms at an industrial level, specifically in the food industry. Full article

The present study demonstrates the potential of the alginate encapsulation of shoot tips and nodal segments of Gardenia jasminoides Ellis, the short-term cold storage of artificial seeds and subsequent successful conversion to desirable, uniform and genetically stable plantlets. Shoot tips and first-node segments below them, derived from shoots of in vitro cultures, responded better than second-to-fourth-node segments on agar-solidified Murashige and Skoog (MS) nutrient medium and thus, they were used as explants for alginate encapsulation. Explant encapsulation in 2.5% sodium alginate in combination with 50 mM of calcium chloride resulted in the production of soft beads, while hardening in 100 mM of calcium chloride formed firm beads of uniform globular shape, suitable for handling. The addition of liquid MS nutrient medium in the sodium alginate solution doubled the subsequent germination response of the beads. The maintenance of alginate beads under light favored their germination response compared to maintenance in darkness. Encapsulated shoot tip explants of gardenia, which were stored at 4 °C for 4, 8 or 12 weeks, showed a gradual decline in their regeneration response (73.3, 68.9, 53.3%, respectively), whereas, non-encapsulated explants (naked), stored under the same time durations of cold conditions, exhibited a sharp decline in regeneration response up to entirely zeroing (48.9, 11.1, 0.0%, respectively). Shoots, derived from 12-week cold-stored encapsulated explants, were easily rooted in solid MS nutrient medium with the addition of 0.5 μM of Indole-3-acetic acid (IAA) and after transplantation of the rooted plantlets individually to pots containing a peat–perlite (3:1, v/v) substrate, they were successfully acclimatized in the greenhouse under the gradual reduction of 75 or 50% shading with survival rates of 95–100%. The genetic stability of the acclimatized plantlets was assessed and compared with the mother plant using inter simple sequence repeat (ISSR) markers. ISSR analysis confirmed that all regenerated plantlets were genetically identical to the mother plant. This procedure of artificial seed production could be useful for the short-term storage of germplasm and the production of genetically identical and stable plants as an alternative method of micropropagation in Gardenia jasminoides. Full article