Antimicrobial Plants Used by Fang Populations and Phytochemical Profiling of Erismadelphus exsul.

Gabon has a rich flora, many species of which are used in traditional medicine. However, little research has been carried out on this wealth. An ethnopharmacological survey in the Fang language was carried out among traditional practitioners to collect antimicrobial medicinal plants. Phytochemical profiling of ethanolic and methanolic extracts from Erismadelphus exsul Mildbr leaves was carried out using HPLC-ESI-Q/TOF and a molecular network approach. Antibacterial activity was assessed with disk diffusion and microdilution methods, antioxidant activity via DPPH and FRAP methods, and in vitro cell viability via Cell Counting Kit-8. A total of 21 medicinal plants were collected, grouped into 10 families, of which the Fabaceae is the most represented. Erismadelphus exsul was chosen for chemical and biological studies due to its citation frequency (RCF = 0.59) and the absence of previous phytochemical studies. These studies revealed 4 major families of natural compounds and annotated 19 compounds for the first time. The crude leaf extract showed significant antioxidant and antibacterial activity. Cytotoxicity studies showed that the leaves were not cytotoxic, unlike the bark. This study underlines the importance of preserving the ancestral knowledge of the Fang populations, while showing promising results for Erismadelphus exsul.

Confocal spectral microscopy, a non-destructive approach to follow contamination and biofilm formation of mCherry Staphylococcus aureus on solid surfaces.

Methods to test the safety of wood material for hygienically sensitive places are indirect, destructive and limited to incomplete microbial recovery via swabbing, brushing and elution-based techniques. Therefore, we chose mCherry Staphylococcus aureus as a model bacterium for solid and porous surface contamination. Confocal spectral laser microscope (CSLM) was employed to characterize and use the autofluorescence of Sessile oak (Quercus petraea), Douglas fir (Pseudotsuga menziesii) and poplar (Populus euramericana alba L.) wood discs cut into transversal (RT) and tangential (LT) planes. The red fluorescent area occupied by bacteria was differentiated from that of wood, which represented the bacterial quantification, survival and bio-distribution on surfaces from one hour to one week after inoculation. More bacteria were present near the surface on LT face wood as compared to RT and they persisted throughout the study period. Furthermore, this innovative methodology identified that S. aureus formed a dense biofilm on melamine but not on oak wood in similar inoculation and growth conditions. Conclusively, the endogenous fluorescence of materials and the model bacterium permitted direct quantification of surface contamination by using CSLM and it is a promising tool for hygienic safety evaluation.

Experimental Parameters Influence the Observed Antimicrobial Response of Oak Wood (Quercus petraea).

The present investigation aimed to utilize a direct wood disc diffusion method to study the influence of plane of cutting, cutting method, sterilization method, and origin of tree on the antimicrobial activity of wood material. Six oak wood trees (Quercus petraea) were collected from 3 different locations in France. They were cut into 4 mm thick slices with either transverse (RT), tangential (LT) or radial (LR) faces. Round discs (diameter 9.95 ± 0.1 mm) were cut from the slices via a laser machine or a manual punch machine, and were sterilized with gamma irradiation (25 kGy) or autoclaving (121 °C). The antimicrobial activity of wood was tested using a direct diffusion method against Staphylococcus aureus and Acinetobacter baumannii isolates. The zone of inhibition around the wooden disc was recorded following the recommendations used for antibiotics tests. The results showed that S. aureus was more susceptible than A. baumannii, to the chemicals that diffused from the wood. The transverse face discs exhibited higher antimicrobial activity. Samples that had been sterilized by autoclaving showed significantly (p < 0.05) lower antimicrobial activity, whereas the cutting method and origin of tree did not influence the antimicrobial activity of wood material. Therefore, the choice of sterilization method and cutting planes must be taken into account while studying and interpreting the antibacterial properties of wood material.

Testing the Antimicrobial Characteristics of Wood Materials: A Review of Methods.

Some wood species have antimicrobial properties, making them a better choice over inert surfaces in certain circumstances. However, the organic and porous nature of wood raises questions regarding the use of this material in hygienically important places. Therefore, it is reasonable to investigate the microbial survival and the antimicrobial potential of wood via a variety of methods. Based on the available literature, this review classifies previously used methods into two broad categories: one category tests wood material by direct bacterial contact, and the other tests the action of molecules previously extracted from wood on bacteria and fungi. This article discusses the suitability of these methods to wood materials and exposes knowledge gaps that can be used to guide future research. This information is intended to help the researchers and field experts to select suitable methods for testing the hygienic safety and antimicrobial properties of wood materials.

Survival of Bacterial Strains on Wood (Quercus petraea) Compared to Polycarbonate, Aluminum and Stainless Steel.

Healthcare-associated infections (HAI) remain a burden in healthcare facilities, environmental surfaces being a potential reservoir for healthcare-associated pathogens. In this context, exploration of materials with potential antimicrobial activities represents a way forward for the future. Here, we explored the survival of four bacterial species commonly involved in HAI (Acinetobacter baumannii, Enterococcus faecalis, Klebsiella pneumoniae, Staphylococcus aureus), on oak versus three other materials (aluminum, polycarbonate, stainless steel). Twenty microliters of each bacterial suspension (approximatively 107 bacteria) were deposited on each material. Bacterial counts were measured by grinding and culturing on day 0, 1, 2, 6, 7 and 15. Analyses were performed in triplicate for each material and each time evaluated. It appeared that the bacteria viable count decreased rapidly on transversal and tangential oak compared with the other materials for all bacterial species. Furthermore, no difference was noticed between transversal and tangential oak. These results underline the potential for use of oak materials in healthcare facilities, a consideration that should be supported by further investigations.

Wood materials for limiting the bacterial reservoir on surfaces in hospitals: would it be worthwhile to go further?

Aim: To assess the activity of Quercus petraea (oak) on five bacterial species/genus frequently involved in hospital-acquired infections for evaluating the interest of going further in exploring the possibilities of using untreated wood as a material in the hospital setting. Materials & methods: We studied the activity of Q. petraea by the disk diffusion method. Results:Q. petraea was active on Staphylococcus aureus and Acinetobacter coalcoaceticus-baumannii complex, two bacterial species particularly resistant in the hospital environment, independently from their resistance to antibiotics, and was slightly active on Pseudomonas aeruginosa. Concurrently, Q. petraea was not active on Enterococci and Escherichia coli. Conclusion: Overall, untreated wood material presented antimicrobial properties that could have an impact on the cross-transmission of certain bacterial species in healthcare settings.

Combination of pyrolysis and hydroliquefaction of CCB-treated wood for energy recovery: optimization and products characterization.

In this paper, pyrolysis and hydroliquefaction processes were successively used to convert CCB-treated wood into bio-oil with respect to environment. Pyrolysis temperature has been optimized to produce maximum yield of charcoal with a high metal content (Cu, Cr, and B). The results obtained indicate that the pyrolysis at 300 °C and 30 min are the optimal conditions giving high yield of charcoal about 45% which contains up to 94% of Cu, 100% of Cr and 88% of B. After pyrolysis process, the charcoal has been converted into bio-oil using hydroliquefaction process. The optimization approach for the yield of bio-oil using a complete factorial design with three parameters: charcoal/solvent, temperature and hydrogen pressure was discussed. It is observed that the temperature is the most significant parameter and the optimum yield of bio-oil is around 82%. The metal analysis shows that the metals present in the bio-oil is very negligible.

Influence of impregnation method on metal retention of CCB-treated wood in slow pyrolysis process.

In the present work, the effects of copper, chromium and boron on the pyrolysis of wood and their distribution in the pyrolysis products were investigated. For this, the wood has been impregnated with chromium-copper-boron (CCB). In addition, to describe the effects of impregnation method, vacuum-pressure and dipping methods were also conducted. Thermogravimetric analysis (TGA) results show that an increase in the final residue and decrease in degradation temperature on both methods of treated wood compared to untreated wood. Then, slow pyrolysis experiments were carried out in a laboratory reactor. The mass balance of pyrolysis products is confirmed by TGA. Furthermore, the concentration of metals in the final residue is measured by inductively coupled plasma mass spectroscopy (ICP-MS). The results show that the final residue contains more than 45% of the initial amount of metal present in the treated wood. The phenomenon is more pronounced with vacuum-pressure treated wood. The heating values of pyrolysis products were analyzed. The heating value of charcoal obtained from treated and untreated wood is approximately same. But the heating value of tar from untreated wood is higher than the heating value of the tar from treated wood.