Fighting bacterial resistance is one of the concerns in modern days, as antibiotics remain the main resource of bacterial control. Data shows that for every antibiotic developed, there is a microorganism that becomes resistant to it. Natural polymers, as the source of antibacterial agents, offer a new way to fight bacterial infection. The advantage over conventional synthetic antibiotics is that natural antimicrobial agents are biocompatible, non-toxic, and inexpensive. Chitosan is one of the natural polymers that represent a very promising source for the development of antimicrobial agents. In addition, chitosan is biodegradable, non-toxic, and most importantly, promotes wound healing, features that makes it suitable as a starting material for wound dressings. This paper reviews the antimicrobial properties of chitosan and describes the mechanisms of action toward microbial cells as well as the interactions with mammalian cells in terms of wound healing process. Finally, the applications of chitosan as a wound-dressing material are discussed along with the current status of chitosan-based wound dressings existing on the market.

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The aim of this research was to investigate the bioremediation conditions of copper in synthetic water. In the present study, copper ions accumulation efficiency was determined using various genetically modified strains of Saccharomyces cerevisiae (EBY100, INVSc1, BJ5465, and GRF18), Pichia pastoris (X-33, KM71H), Escherichia coli (XL10 Gold, DH5α, and six types of BL21 (DE3)), and Escherichia coli BL21 (DE3) OverExpress expressing two different peroxidases. Viability tests of yeast and bacterial strains showed that bacteria are viable at copper concentrations up to 2.5 mM and yeasts up to 10 mM. Optical emission spectrometry with inductively coupled plasma analysis showed that the tolerance of bacterial strains on media containing 1 mM copper was lower than the tolerance of yeast strains at the same copper concentration. The E. coli BL21 RIL strain had the best copper accumulation efficiency (4.79 mg/L of culture normalized at an optical density of 1.00), which was 1250 times more efficient than the control strain. The yeast strain S. cerevisiae BJ5465 was the most efficient in copper accumulation out of a total of six yeast strains used, accumulating over 400 times more than the negative control strain. In addition, E. coli cells that internally expressed recombinant peroxidase from Thermobifida fusca were able to accumulate 400-fold more copper than cells that produced periplasmic recombinant peroxidases.

Triticonazole is a fungicide used to control diseases in numerous plants. The commercial product is a racemate containing (R)- and (S)-triticonazole and its residues have been found in vegetables, fruits, and drinking water. This study considered the effects of triticonazole on soil microorganisms and enzymes and human health by taking into account the enantiomeric structure when applicable. An experimental method was applied for assessing the effects of triticonazole on soil microorganisms and enzymes, and the effects of the stereoisomers on soil enzymes and human health were assessed using a computational approach. There were decreases in dehydrogenase and phosphatase activities and an increase in urease activity when barley and wheat seeds treated with various doses of triticonazole were sown in chernozem soil. At least 21 days were necessary for the enzymes to recover the activities. This was consistent with the diminution of the total number of soil microorganisms in the 14 days after sowing. Both stereoisomers were able to bind to human plasma proteins and were potentially inhibitors of human cytochromes, revealing cardiotoxicity and low endocrine disruption potential. As distinct effects, (R)-TTZ caused skin sensitization, carcinogenicity, and respiratory toxicity. There were no significant differences in the interaction energies of the stereoisomers and soil enzymes, but (S)-TTZ exposed higher interaction energies with plasma proteins and human cytochromes.

Chitooligosaccharides (COs) containing up to 10 monomeric units of Nacetyl D-glucosamine and/or D-glucosamine are water-soluble molecules revealing numerous biological activities and low toxicological profiles. Within this study, a computational approach has been used to predict the involvement of the COs having distinct chemical properties (molecular weight, deacetylation degree and acetylation pattern) in all the four wound healing phases: hemostasis, inflamemation, proliferation and tissue remodeling. There are predictions, for the investigated COs, regarding their molecular targets and the biological activities that are reliant to the wound healing process. Furthermore, a molecular docking approach was used to assess the interactions of the investigated COs with the myeloid differentiation factor 2 (MD-2), a protein involved in the inflammatory processes. The investigation confirms the functional roles of the investigated COs in wound healing. The molecular targets predicted for the COs containing totally and partially acetylated units are galectins and selectins and those predicted for COs containing totally deacetylated units are fibroblast growing factors, the COs containing 3 units revealing the higher number of molecular targets. All these proteins are involved in mediating immune response, inducing cell division, growth and cell adhesion during the process of wound healing. All the COs containing from 2 to 8 monomeric units are able to interact with the MD-2 protein, the interactions being stronger for the COs containing 6 and 8 monomeric units. The interaction energies increase with the increasing molecular weight and with decreasing deacetylation degree and are reliant on acetylation patterns. Among the investigated COs, the totally acetylated COs containing 6 and 8 N-acetyl glucosamine units can be better inhibitors of the LPS binding to MD-2 protein. Consequently, mixtures of COs with distinct properties should be considered suitable candidates as adjuvants in developing scaffolds for the wound healing process.