Lignins and lignin-derived compounds are known to have antibacterial properties. The wound healing agents in the form of dressings produce faster skin repair and decrease pain in patients. In order ...to create an efficient antimicrobial agent in the form of dressing in the treatment of chronic wounds, a composite hydrogel of bacterial cellulose (BC) and dehydrogenative polymer of coniferyl alcohol (DHP), BC-DHP, was designed. Novel composite showed inhibitory or bactericidal effects against selected pathogenic bacteria, including clinically isolated ones. The highest release rate of DHP was in the first hour, while after 24 h there was still slow release of small amounts of DHP from BC-DHP during 72 h monitoring. High-performance liquid chromatography coupled with mass-spectrometry showed that BC-DHP releases DHP oligomers, which are proposed to be antimicrobially active DHP fractions. Scanning electron microscopy and atomic force microscopy micrographs proved a dose-dependent interaction of DHP with BC, which resulted in a decrease of the pore number and size in the cellulose membrane. The Fourier-transform infrared absorption spectra of the BC-DHP showed that DHP was partly bound to the BC matrix. The swelling and crystallinity degree were dose-dependent. All obtained results confirmed BC-DHP composite as a promising hydrogel for wounds healing.
•Novel composite BC-DHP in form of dressing showed inhibitory/bactericidal effect.•BC-DHP showed highest release of the active substance during the first 24 h.•Released active compounds were oligomers of coniferyl alcohol.•High swellability of hydrogel confirmed its potential role in chronic wound healing.
The increased antibiotic resistance of pathogenic bacteria requires intense research of new wound healing agents. Novel wound dressings should be designed to provide wound disinfection, good ...moisture, and fast epithelization. In this study, bacterial cellulose (BC) was impregnated with graphene quantum dots (GQDs) for potential use in wound healing treatment. The BC was successfully loaded with approximately 11.7 wt% of GQDs. The actual release of GQDs from new designed composite hydrogels were 13%. Novel GQDs‐BC hydrogel composites are biocompatible and showed significant inhibition towards Staphylococcus aureus and Streptococcus agalactiae and bactericidal effect towards Methicillin‐resistant Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa. The in vitro healing analysis showed significant migration of human fibroblasts after the GQDs‐BC hydrogels application. Furthermore, after 72 h exposure to GQDs‐BC, endothelial nitric oxide synthase, vascular endothelial growth factor A, matrix metallopeptidase 9, and Vimentin gene expression in fibroblast were significantly upregulated promoting angiogenesis. GQDs‐BC hydrogel composites showed very good wound fluid absorption and water retention, which satisfies good dressing properties. All obtained results propose new designed GQDs‐BC hydrogels as potential wound dressings.
Biocompatible GQDs‐BC composite hydrogel accelerates wound healing.
Plant inoculation with endophytic bacteria that normally live inside the plant without harming the host is a highly promising approach for biological disease control. The mechanism of resistance ...induction by beneficial bacteria is poorly understood, because pathways are only partly known and systemic responses are typically not seen. The innate endophytic community structures change in response to external factors such as inoculation, and bacterial endophytes can exhibit direct or indirect antagonism towards pathogens. Earlier we showed that resistance induction by an endophytic Methylobacterium sp. in potato towards Pectobacterium atrosepticum was dependent on the density of the inoculum, whereas the bacterium itself had no antagonistic activity. To elucidate the role of innate endophyte communities in plant responses, we studied community changes in both in vitro and greenhouse experiments using various combinations of plants, endophyte inoculants, and pathogens. Induction of resistance was studied in several potato (Solanum tuberosum L.) cultivars by Methylobacterium sp. IMBG290 against the pathogens P. atrosepticum, Phytophthora infestans and Pseudomonas syringae pv. tomato DC3000, and in pine (Pinus sylvestris L.) by M. extorquens DSM13060 against Gremmeniella abietina. The capacities of the inoculated endophytic Methylobacterium spp. strains to induce resistance were dependent on the plant cultivar, pathogen, and on the density of Methylobacterium spp. inoculum. Composition of the endophyte community changed in response to inoculation in shoot tissues and correlated with resistance or susceptibility to the disease. Our results demonstrate that endophytic Methylobacterium spp. strains have varying effects on plant disease resistance, which can be modulated through the endophyte community of the host.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Since the pathogenic bacteria biofilms are involved in 70% of chronic infections and their resistance to antibiotics is increased, the research in this field requires new healing agents.
New ...composite hydrogels were designed as potential chronic wound dressings composed of bacterial cellulose (BC) with chitosan polymer (Chi) – BC-Chi and chitosan nanoparticles (nChiD) – BC-nChiD. nChiD were obtained by gamma irradiation at doses: 20, 40 and 60 kGy. Physical and chemical analyses showed incorporation of Chi and encapsulation of nChiD into BC. The BC-Chi has the highest average surface roughness. BC-nChiD hydrogels show an irradiated dose-dependent increase of average surface roughness. New composite hydrogels are biocompatible with excellent anti-biofilm potential with up to 90% reduction of viable biofilm and up to 65% reduction of biofilm height. The BC-nChiD showed better dressing characteristics: higher porosity, higher wound fluid absorption and faster migration of cells (in vitro healing). All obtained results confirmed both composite hydrogels as promising chronic wound healing agents.
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•Chitosan dots used in hydrogel composing were obtained by gamma irradiation.•New designed composite hydrogels are biocompatible.•New hydrogels reduce pathogenic biofilm up to 90% and their height up to 65%.•Hydrogels with chitosan dots have better wound fluid absorption and cell migration.•Hydrogels with chitosan dots showed better potential role in chronic wound healing.
is the dominant taxon and cellulose-producing bacteria in the Kombucha Microbial Community (KMC). This is the first study to isolate the
genome from a reactivated space-exposed KMC sample and ...comprehensively characterize it. The space-exposed genome was compared with the Earth-based reference genome to understand the genome stability of
under extraterrestrial conditions during a long time. Our results suggest that the genomes of
IMBG180 (ground sample) and
IMBG185 (space-exposed) are remarkably similar in topology, genomic islands, transposases, prion-like proteins, and number of plasmids and CRISPR-Cas cassettes. Nonetheless, there was a difference in the length of plasmids and the location of
genes. A small difference was observed in the number of protein coding genes. Despite these differences, they do not affect any genetic metabolic profile of the cellulose synthesis, nitrogen-fixation, hopanoid lipids biosynthesis, and stress-related pathways. Minor changes are only observed in central carbohydrate and energy metabolism pathways gene numbers or sequence completeness. Altogether, these findings suggest that
maintains its genome stability and functionality in KMC exposed to the space environment most probably due to the protective role of the KMC biofilm. Furthermore, due to its unaffected metabolic pathways, this bacterial species may also retain some promising potential for space applications.
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► Growth promotion by endophytes was not correlated with enhanced disease resistance. ► Disease resistance was associated with the moderate activation of antioxidant system. ► Potato ...endophytes were able to induce disease resistance via priming.
Priming plants by non-pathogenic bacteria allows the host to save energy and to reduce time needed for development of defense reaction during a pathogen attack. However, information on the role of endophytes in plant defense is limited. Here, the ability of endophytic bacteria to promote growth and resistance of potato plants towards infection by the necrotroph
Pectobacterium atrosepticum was studied. A
Pseudomonas sp. strain was selected due to antagonism towards bacterial pathogens and a
Methylobacterium sp. strain because of efficient plant colonization. The aim of this study was to find if there is any correlation between plant growth promotion and induction of resistance by endophytes of potato, as well as to study the putative mechanisms of endophytes interacting with the plant during resistance induction. Both tested strains promoted growth of potato shoots but only the
Pseudomonas sp. increased potato resistance towards the soft rot disease. Induction of disease resistance by the
Methylobacterium sp. was inversely proportional to the size of bacterial population used for inoculation. The plant antioxidant system was moderately activated during the induction of resistance by the biocontrol strains. qPCR data on expression of marker genes of induced systemic resistance and acquired systemic resistance in endophyte-infected
Arabidopsis plants showed activation of both salicylic acid and jasmonate/ethylene-dependent pathways after challenge inoculation with the pathogen. We suggest that some endophytes have the potential to activate both basal and inducible plant defense systems, whereas the growth promotion by biocontrol strains may not correlate with induction of disease resistance.
Rice is a major staple food across the globe. Its growth and productivity is highly dependent on the rhizobiome where crosstalk takes place between plant and the microbial community. Such ...interactions lead to selective enrichment of plant beneficial microbes which ultimately defines the crop health and productivity. In this study, rhizobiome modulation is documented throughout the development of rice plant. Based on 16S rRNA gene affiliation at genus level, abundance, and diversity of plant growth promoting bacteria increased during the growth stages. The observed α diversity and rhizobiome complexity increased significantly (
p
< 0.05) during plantation. PCoA indicates that different geographical locations shared similar rhizobiome diversity but exerted differential enrichment (
p
< 0.001). Diversity of enriched genera represented a sigmoid curve and subsequently declined after harvest. A major proportion of dominant enriched genera (
p
< 0.05, abundance > 0.1%), based on 16S rRNA gene, were plant growth promoting bacteria that produces siderophore, indole-3-acetic acid, aminocyclopropane-1-carboxylic acid, and antimicrobials. Hydrogenotrophic methanogens dominated throughout cultivation. Type I methanotrophs (
n
= 12) had higher diversity than type II methanotrophs (
n
= 6). However, the later had significantly higher abundance (
p
= 0.003). Strong enrichment pattern was also observed in type I methanotrophs being enriched during water logged stages. Ammonia oxidizing Archaea were several folds more abundant than ammonia oxidizing bacteria. K-strategists
Nitrosospira
and
Nitrospira
dominated ammonia and nitrite oxidizing bacteria, respectively. The study clarifies the modulation of rhizobiome according to the rice developmental stages, thereby opening up the possibilities of bio-fertilizer treatment based on each cultivation stages.
Therapy of bacterial urinary tract infections (UTIs) and catheter associated urinary tract infections (CAUTIs) is still a great challenge because of the resistance of bacteria to nowadays used ...antibiotics and encrustation of catheters. Bacterial cellulose (BC) as a biocompatible material with a high porosity allows incorporation of different materials in its three dimensional network structure. In this work a low molecular weight chitosan (Chi) polymer is incorporated in BC with different concentrations. Different characterization techniques are used to investigate structural and optical properties of these composites. Radical scavenging activity test shows moderate antioxidant activity of these biocompatible composites whereas
in vitro
release test shows that 13.3% of chitosan is released after 72 h. Antibacterial testing of BC-Chi composites conducted on Gram-positive and Gram-negative bacteria causing UTIs and CAUTIs (
Escherichia coli
,
Pseudomonas aeruginosa
,
Klebsiella pneumoniae
) and encrustation (
Proteus mirabilis
) show bactericidal effect. The morphology analysis of bacteria after the application of BC-Chi shows that they are flattened with a rough surface, with a tendency to agglomerate and with decreased length and width. All obtained results show that BC-Chi composites might be considered as potential biomedical agents in treatment of UTIs and CAUTIs and as a urinary catheter coating in encrustation prevention.
Bacterial cellulose-chitosan composite with antibacterial and moderate antioxidant activity for potential UTI/CAUTI treatment and catheter coating in encrustation prevention.
Kombucha mutualistic community (KMC) is composed by acetic acid bacteria and yeasts, producing fermented tea with health benefits. As part of the BIOlogy and Mars EXperiment (BIOMEX) project, the ...effect of Mars-like conditions on the KMC was analyzed. Here, we analyzed metagenomeassembled genomes (MAGs) of the Komagataeibacter, which is a predominant genus in KMC, to understand their roles in the KMC after exposure to Mars-like conditions (outside the International Space Station) based on functional genetic elements. We constructed three MAGs: K. hansenii, K. rhaeticus, and K. oboediens. Our results showed that (i) K. oboediens MAG functionally more complex than K. hansenii, (ii) K. hansenii is a keystone in KMCs with specific functional features to tolerate extreme stress, and (iii) genes related to the PPDK, betaine biosynthesis, polyamines biosynthesis, sulfate-sulfur assimilation pathway as well as type II toxin-antitoxin (TA) system, quorum sensing (QS) system, and cellulose production could play important roles in the resilience of KMC after exposure to Mars-like stress. Our findings show the potential mechanisms through which Komagataeibacter tolerates the extraterrestrial stress and will help to understand minimal microbial composition of KMC for space travelers
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