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Sorbic acid-loaded chitosan/tripolyphosphate nanoparticles (SANs) have previously been shown to exert both antibacterial and antioxidant effects on Chinese sausage. In this study, the minimum inhibitory concentrations (MICs) of SANs against two Pseudomonas aeruginosa strains were determined. The blank control group (BC) served as the negative control, while the chitosan/tripolyphosphate nanoparticles (CTNs) group and free sorbic acid (SA) group served as the positive controls. Tests conducted under five different pH conditions (5/6/7/8/9) revealed that the SANs exhibited a good bacteriostatic effect against P. aeruginosa. Variations in the metabolism, cell membrane or cell wall integrity, and morphology of P. aeruginosa were measured to evaluate the effects of SANs on their intracellular and extracellular components. The MIC of SANs for the two P. aeruginosa strains was determined to be 150 μg/mL. SANs delayed the growth of P. aeruginosa and severely damaged both its inner and outer cell membranes. The heteromorphism of the bacteria as observed by field emission scanning electron microscopy (FESEM), verified the aforementioned results. The results showed SANs could effectively inhibit the growth of P. aeruginosa and exert antibacterial ability in a wider range of acid-base environments. This study broadens the application of SANs in food processing and provides experimental basis. [ABSTRACT FROM AUTHOR]

Pressure ulcer dressings with different functions can enhance wound healing ability to varying degrees; however, pressure ulcer dressings that integrate various functions and break the resistance of bacteria to traditional antibiotics have not been widely studied. We proposed a self-pumping/super-absorbent/transportable drug dressing (PLD-SLD), polycaprolactone (PCL)/sodium alginate (SA) was used to load platelet-derived growth factor (PDGF) and lidocaine hydrochloride (LID) by Janus electrospinning and self-assembly technology, and Ɛ-polylysine was used as a biological bacteriostatic agent to prepare a multi-layer dressing. SEM showed that the dressing had a fluffy structure. The dressing can pump the exudate to the SA layer away from the skin. The swelling ratio reached 1378.667 ± 44.752 %. Coagulate blood in 5 min. On the 8th day, the unclosed area rate of the PLD-SLD dressing group was 16.112 ± 0.088 % lower than that of the model group. Importantly, the dressing can induce the expression of CD31, VEGF, α-SMA, and reduce the expression of CD68, thereby giving priority to wound healing. There was no scar formation after healing. In this study, a new dressing preparation method was proposed for the problems of exudate management, infection control, pain relief and healing promotion of stage 3–4 pressure ulcer healing. [Display omitted] • Non-antibiotic resistance, the use of biological preservatives to obtain antibacterial properties • Semi-fiber structure, staggered groove structure, non-stratified form • One-way pumping exudate, strong liquid absorption • Dressing is multifunctional, with antibacterial, analgesic, and rapid healing effects. • Promote vascularization, reduce inflammation, and guide the closure of skin gaps [ABSTRACT FROM AUTHOR]

The full combination of high sensitivity indication and long-lasting bacteriostatic function is an innovative need to meet the practicality of intelligent film packaging systems for food products. Hence, Blueberry anthocyanins (BA) copigmentated by ferulic acid (FA) was used as an indicator, and cinnamon essential oil (CO) encapsulated by β-cyclodextrin (β-CD) as a bacteriostat, potato starch (PS) as a film-forming substrate to prepared a dual-function starch-based intelligent active packaging film with pH indicator and antibacterial function. FA had the best copigmentation effect with a threefold increase in a value compared to other phenolic acids. The Δ E value increased from 3.24 to 5.13 at pH 2–8, and the change was still prominent in acid-base alternating test, indicating a high response sensitivity. Notably, the yellow gamut of indicating terminus increased its visibility to the naked eye. The release behavior of CO from film was in line with Fick's diffusion. Meanwhile, the release of CO delayed to about 90 h through β-cyclodextrin encapsulation, showing a high growth-inhibition rate in E. coli and S. aureus of almost 100 %. In this study, a dual-function film with indication and bacteriostasis was prepared and enhanced with both, expanding its wide application in intelligent packaging of fresh food. [Display omitted] • A dual-function film with indication and bacteriostasis was constructed • Copigmention facilitated pH responsive sensitivity and reversibility of films • Slow-release behavior of essential oils from β-cyclodextrin conformed to Fick model • Film exhibited long-term bacteriostasis via inhibiting S. aureus and E. coli [ABSTRACT FROM AUTHOR]

Abstract d ‑Phenyllactic acid (d ‑PLA) shows great potential for biopreservative production owning to its anti-microbial activity. In this study, strain ZX1, which could inhibit the growth of other microbes was isolated and identified as Lactobacillus genus. Strain ZX1 could produce d ‑PLA with 0.16 g·L−1. Furthermore, a novel d ‑lactate dehydrogenase gene was identified and expressed in Escherichia coli BL21 (DE3) with the specific activity of 71.64 U·mg−1 protein under the optimal temperature and pH of 35 °C and 6.2. The kinetic constants for K cat , K m , V max were 10.71 s−1, 2.356 mM and 11.27 μM·mg−1·min−1 for phenylpyruvic acid (PPA), respectively. 18.21 g·L−1 d ‑PLA from PPA with yield of 90.49% and productivity of 2.49 g·L−1·h−1 was obtained by the recombinant E. coli BL21 harboring d ‑LDH, indicating that engineered E. coli BL21 (d ‑LDH) has excellent potential in commercial d ‑PLA production. Highlights • An excellent anti-microbial strain ZX1 was isolated. • Strain ZX1 was a superior d ‑PLA-producing wild strain. • A novel ldhD gene from strain ZX1 was cloned, expressed and characterized. • E. coli BL21 (d ‑LDH) provided a high productivity and conversion yield. [ABSTRACT FROM AUTHOR]

In order to find a degradable biofilm，edible films of Auricularia auricula polysaccharide (AAP) were prepared and characterized optically, morphologically, and mechanically in terms of barrier, bactericidal, and antioxidant properties and evaluated for their potential application in cold meat packaging. The results showed that films prepared from 40 % AAP had the best mechanical properties, with smooth and homogeneous surfaces, good water barrier properties and also good preservation of cold meat. Thus, Auricularia auricula polysaccharide is a composite membrane additive with great potential for application. • Preparation of Auricularia auricula polysaccharide-based films • Characterization of A. auricula polysaccharide-based films • Evaluation of A. auricula polysaccharide-based films for the meat preservation [ABSTRACT FROM AUTHOR]

Abstract: In this paper, rod-like chitin whisker was used as a filler to reinforce the chitosan membrane, and a series of composite membranes were prepared by casting–evaporation method. Mechanical testing shows that tensile strength of the resulting composite membrane with 3wt% chitin whisker content reaches up to 110.3MPa, which is about 2.8times than that of neat chitosan membrane (38.5MPa), and moisture regain of all composite membranes presents a decreasing tendency with increasing content of chitin whisker. Furthermore, SEM was used to investigate the morphology difference between neat chitosan membrane and composite membranes, to understand the reinforce mechanism of chitin whisker. Wide angle x-ray diffraction and Fourier transform infrared spectroscopy were used to visualize the structure change before and after the compositing processes. Besides, the bacterostatic test shows that this composite membrane presents effective inhibitory effect on Staphylococcus aureus, Escherchia coli and Corinebaterium michiganence respectively, which indicates it a promising material for packaging and wound dressing. [Copyright &y& Elsevier]

Abstract: Schiff''s base of chitosan (BCTS) was obtained by the reaction of chitosan (CTS) and benzaldehyde. Then BCTS reacted with acyl chloride which was synthesized by p-aminobenzoic acid and thionyl chloride to get N-benzoyl-O-aminobenzoyl chitosan ester (BABCTSE), removing the groups of amino protection of BABCTSE to get the final product (ABCTSE). The structures of the derivatives were characterized by FT-IR, 1H NMR, 13C NMR and elemental analysis. The elemental analysis results indicated that the degrees of substitution (DS) of the products were 16.8% and 40.4%. The synthesized compounds exhibited an excellent solubility in organic solvents. TG and DTG results showed that thermal stability of the derivatives was lower than that of chitosan. In addition, the existence of two different amido in the molecular structures contributed to forming more –NH3 + in the acid solution which could make the derivatives have a greater advantage in the field of bacteriostasis. [Copyright &y& Elsevier]