Antibacterial Activity of Biocellulose with Oregano Essential Oil against Cronobacter Strains

Investigation of anti-adherence and antimicrobial properties of prodigiosin-functionalized bacterial cellulose membrane for biomedical applications

In this study, novel biomaterial that consisted entirely of bacterial products was developed with the approach of designing cost effective material for biomedical applications. With this aim, bacterial cellulose membranes (BCMs) which synthesized by Komagataeibacter intermedius were produced. Moreover, to impart antimicrobial properties to enhance the capacity of BCMs for biomedical usage, prodigiosin (PG) pigment of Serratia marcescens which presents wide range of antimicrobial activities was loaded to BCMs. Firstly, high yield of PG production was achieved, and then crude pigment was purified with silica gel column. The purified PG was characterized with thin layer chromatography and UV-visible spectrometry. The antimicrobial effect of the produced pigment on Gram-positive and negative bacteria and a yeast was investigated. The success of modification in PG-modified BCMs has been demonstrated by FTIR and SEM. Moreover, antimicrobial and antiadhesive ability of novel PG-BCMs were examined with disc diffusion and plate counting methods. As a result, it was established that PG-BCMs were able to inhibit the growth of all tested microorganisms. Furthermore, excellent antiadhesive effect was observed for the tested microorganisms with the inhibition rates of 82.05-96.25 %. Finally, cytotoxicity test with L929 cell line demonstrated that PG-BCM is biocompatible at a level that can be applied in in vivo studies.

Reinforcing effect of ε-polylysine-carboxymethyl chitosan nanoparticles on gelatin-based film: Enhancement of physicochemical, antioxidant, and antibacterial properties

The development and application of antibacterial film were highly anticipated to prevent food spoilage caused by bacteria. In this investigation, antibacterial and antioxidant functionalized gelatin-based film was formed with the incorporation of oregano essential emulsion Pickering emulsion (OPE). ε-Polylysine-Carboxymethyl Chitosan nanoparticles (CMCS-ε-PL) composed of different mass ratios of CMCS and ε-PL were orchestrated by electrostatic forces and hydrogen bonding, which effectively acted as a stabilizer for OPE. The design of different mass ratios of CMCS and ε-PL in CMCS-ε-PL has a deep effect on the structure and functional properties of OPE and film. It successfully improved the encapsulation efficiency of OPE from 49.52 % to 79.83 %. With the observation of AFM images, the augmentation of surface roughness consequent to OPE incorporation can be relieved by the increased contention of ε-PL in CMCS-ε-PL. Meanwhile, the mechanical properties, barrier properties, anti-oxidation, and antibacterial properties of the films were improved with the incorporation of the above OPE. In particular, a synergistic antibacterial activity between ε-PL and OEO in the film was demonstrated in this study and the mechanism of enhanced antibacterial activity was elucidated by examining the integrity of bacteria cell membrane. The film unequivocally demonstrated its ability to appreciably prolong the shelf life of both beef and strawberries with excellent antioxidant and antibacterial properties.

Synthesis of Extract-Bacterial Cellulose Composite Using Ageratum conyzoides L. and Chromolaena odorata L., Its Antibacterial Activities, and Biodegradability Properties

Bacterial cellulose is a natural polymer produced by fermentation of coconut water using Acetobacter xylinum bacteria. This study aimed to synthesize a novel composite of bacterial cellulose impregnated with plant extracts that had an antibacterial activity that have the potential to be used as a food packaging material to maintain food quality. Pure bacterial cellulose (pure BC) was impregnated using Ageratum conyzoides L. leaf extract (AC-BC) and Chromolaena odorata L. leaf extract (CO-BC), which contain secondary metabolites with potential as antibacterial. The study began with the synthesis of pure BC, AC-BC, and CO-BC composites then characterized by SEM-EDX and FTIR, continued with antibacterial activity tests against S. aureus, S. typhimurium, E. coli, and their biodegradability tests. The results of SEM and FTIR characterization showed the success of the impregnation process for antibacterial compounds. The results of the antibacterial activity of AC-BC disc diffusion against S. typhimurium and E. coli showed good antibacterial activity of 9.82 mm and 8.41 mm, respectively. The similar result showed with the antibacterial activity of CO-BC disc diffusion against S. typhimurium and E. coli that showed good activity of 9.73 mm and 6.82 mm, respectively. On the other hand, the biodegradability test showed that the impregnation of bacterial cellulose slowed down the degradation process in the soil. This study confirmed the potential application of bacterial cellulose-plant extracts as an active and biodegradable food packaging.

Antibacterial Potential of Bacterial Cellulose Impregnated with Green Synthesized Silver Nanoparticle Against S. aureus and P. aeruginosa

In this study, bacterial cellulose (BC) impregnated with green synthesized silver nanoparticles (AgNPs) is evaluated as an antimicrobial membrane for wound-healing treatment. Green synthesized silver nanoparticles using Moringa oleifera leaf extract were characterized using UV‒visible spectroscopy, FTIR, X-ray diffraction, and transmission electron microscopy. The results confirmed that the resulted particles were Ag₂O and metallic Ag in nanoscale with an average size ranged from 24 to 40 nm. The green synthesized nanoparticles incorporated within both bacterial cellulose and filter paper discs showed excellent antibacterial activities against Staphylococcus aureus ATCC 6538 and Pseudomonas aeruginosa ATCC 9027. There was no significant difference noticed between bacterial cellulose and filter paper holding capacity to nanoparticles and there was lack of interaction between bacterial cellulose and impregnated nanoparticles as elaborated by Fourier transform infrared spectral analyses. Scanning electron microscopy investigation showed major distortions effects of green synthesized silver nanoparticles on bacterial cell morphology.

Valorization of nano-based lignocellulosic derivatives to procure commercially significant value-added products for biomedical applications

Biowaste, produced from nature, is preferred to be a good source of carbon and ligninolytic machinery for many microorganisms. They are complex biopolymers composed of lignin, cellulose, and hemicellulose traces. This biomass can be depolymerized to its nano-dimensions to gain exceptional properties useful in the field of cosmetics, pharmaceuticals, high-strength materials, etc. Nano-sized biomass derivatives overcome the inherent drawbacks of the parent material and offer promises as a potential material for a wide range of applications with their unique traits such as low-toxicity, biocompatibility, biodegradability and environmentally friendly nature with versatility. This review focuses on the production of value-added products feasible from nanocellulose, nano lignin, and xylan nanoparticles which is quite a novel study of its kind. Dawn of nanotechnology has converted bio waste by-products (hemicellulose and lignin) into useful precursors for many commercial products. Nano-cellulose has been employed in the fields of electronics, cosmetics, drug delivery, scaffolds, fillers, packaging, and engineering structures. Xylan nanoparticles and nano lignin have numerous applications as stabilizers, additives, textiles, adhesives, emulsifiers, and prodrugs for many polyphenols with an encapsulation efficiency of 50%. This study will support the potential development of composites for emerging applications in all aspects of interest and open up novel paths for multifunctional biomaterials in nano-dimensions for cosmetic, drug carrier, and clinical applications.

Comparison of Origanum Essential Oil Chemical Compounds and Their Antibacterial Activity against Cronobacter sakazakii

Origanum vulgare L. (oregano) is an aromatic plant with wide applications in the food and pharmaceutical industries. Cronobacter sakazakii, which has a high detection rate in powdered infant formula, adversely impacts susceptible individuals. Oregano essential oil (OEO) is a natural antibacterial agent that can be used to fight bacterial contamination. Here, OEO chemical compounds from eight oregano varieties were analyzed by gas chromatography–mass spectrometry and their antibacterial properties were assessed. The eight OEOs were clustered into two groups and were more diverse in group 2 than in group 1. Six compounds, including p-cymene, 3-thujene, γ-terpinene, thymol, carvacrol, and caryophyllene, were shared by eight OEOs. Among the eight oregano varieties, OEOs from O. vulgare sc2 had the strongest antibacterial activity against C. sakazaki, with the inhibition zone of 18.22mm. OEOs from O. vulgare jx, O. ‘Nvying’, O. vulgare ‘Ehuang’, and O. vulgare ssp. virens were also potent. Moreover, the antibacterial activity of OEOs was positively correlated with the relative content of thymol. As the main OEO antibacterial compound, thymol affected the normal growth and metabolism of C. sakazakii cells by destroying the bacterial membrane and decreasing the intracellular ATP concentration. Thus, in light of the antibacterial activity detected in the OEOs from the eight oregano varieties, this study provides a theoretical foundation for oregano cultivar management and development.

Insights into the mechanisms of Cronobacter sakazakii virulence

Cronobacter species have adapted to survive harsh conditions, particularly in the food manufacture environment, and can cause life-threatening infections in susceptible hosts. These opportunistic pathogens employ a multitude of mechanisms to aid their virulence throughout three key stages: environmental persistence, infection strategy, and systemic persistence in the human host. Environmental persistence is aided by the formation of biofilms, development of subpopulations, and high tolerance to environmental stressors. Successful infection in the human host involves several mechanisms such as protein secretion, motility, quorum sensing, colonisation, and translocation. Survival inside the host is achieved via competitive acquisition and utilization of minerals and metabolites respectively, coupled with host immune system evasion and antimicrobial resistance (AMR) mechanisms. Across the globe, Cronobacter sakazakii is associated with often fatal systemic infections in populations including neonates, infants, the elderly and the immunocompromised. By providing insight into the mechanisms of virulence utilised by this pathogen across these three stages, this review identifies current gaps in the literature. Further research into these virulence mechanisms is required to inform novel mitigation measures to improve global food safety with regards to this food-borne pathogen.

Active Potential of Bacterial Cellulose-Based Wound Dressing: Analysis of Its Potential for Dermal Lesion Treatment

The use of innate products for the fast and efficient promotion of healing process has been one of the biomedical sector's main bets for lesion treatment modernization process. The aim of this study was to develop and characterize bacterial cellulose-based (BC) wound dressings incorporated with green and red propolis extract (2 to 4%) and the active compounds p-coumaric acid and biochanin A (8 to 16 mg). The characterization of the nine developed samples (one control and eight active wound dressings) evidenced that the mechanics, physics, morphological, and barrier properties depended not only on the type of active principle incorporated onto the cellulosic matrix, but also on its concentration. Of note were the results found for transparency (28.59-110.62T₆₀₀ mm^-1), thickness (0.023-0.046 mm), swelling index (48.93-405.55%), water vapor permeability rate (7.86-38.11 g m² day^-1), elongation (99.13-262.39%), and antioxidant capacity (21.23-86.76 μg mL^-1). The wound dressing based on BC and red propolis was the only one that presented antimicrobial activity. The permeation and retention test revealed that the wound dressing containing propolis extract presented the most corneal stratum when compared with viable skin. Overall, the developed wound dressing showed potential to be used for treatment against different types of dermal lesions, according to its determined proprieties.

Antimicrobial Properties of Bacterial Cellulose Films Enriched with Bioactive Herbal Extracts Obtained by Microwave-Assisted Extraction

The use of bacterial cellulose (BC) as scaffold for active biofilms is one of the most interesting applications, especially for the biomedical and food industries. However, there are currently few studies evaluating the potential of incorporating herbal extracts into various biomaterials, including BC. Thus, the aim of this study is to report a screening of the total phenolic content and antioxidant and antimicrobial activity of ethanolic extracts of oregano, rosemary, parsley, and lovage. At the same time, the bioactive potential of BC enriched with the four ethanolic extracts is described. Microwave-assisted extraction was used to extract bioactive compounds from the four selected herbs. The physical, mechanical, structural, and chemical properties of BC were also assessed. Next, BC was enriched with the extracts, and their effect against Escherichia coli, Staphylococcus aureus, and Candida albicans was evaluated. The results showed that the bioactivity of the herbs varied significantly, with rosemary extract being the most bioactive. The BC films possessed good mechanical properties, and a three-dimensional network fibrillar structure appropriate for ethanolic-extract incorporation. The BC samples enriched with rosemary extracts had the highest antibacterial activity against S. aureus, while E. coli. and C. albicans seemed to be resistant to all extracts, regardless of herbs.

Assessing effectiveness of Komagataeibacter strains for producing surface-microstructured cellulose via guided assembly-based biolithography

In this study, a medical device made of surface microstructured bacterial cellulose was produced using cellulose-producing acetic acid bacteria wild-type strains in combination with guided assembly-based biolithography. The medical device aims at interfering with the cell's focal adhesion establishment and maturation around implantable devices placed in soft tissues by the symmetrical array on its surface. A total of 25 Komagataeibacter strains was evaluated over a three-step selection. In the first step, the ability of strains to produce a suitable bacterial cellulose layer with high production yield was examined, then nine strains, with a uniform and smooth layer of bacterial cellulose, were cultured in a custom-made silicone bioreactor and finally the characteristics of the symmetrical array of topographic features on the surface were analysed. Selected strains showed high inter and intra species variability in bacterial cellulose production. The devices obtained by K2G30, K1G4, DSM 46590 (Komagataeibacter xylinus), K2A8 (Komagataeibacter sp.) and DSM 15973^T (Komagataeibacter sucrofermentas) strains were pouched-formed with hexagonal surface pattern required for reducing the formation of fibrotic tissue around devices, once they are implanted in soft tissues. Our findings revealed the effectiveness of the selected Komagataeibacter wild-type strains in producing surface microstructured bacterial cellulose pouches for making biomedical devices.