Proteobacteria from the human skin microbiota: Species-level diversity and hypotheses

The human skin microbiota is quantitatively dominated by Gram-positive bacteria, detected by both culture and metagenomics. However, metagenomics revealed a huge variety of Gram-negative taxa generally considered from environmental origin. For species affiliation of bacteria in skin microbiota, clones of 16S rRNA gene and colonies growing on diverse culture media were analyzed. Species-level identification was achieved for 81% of both clones and colonies. Fifty species distributed in 26 genera were identified by culture, mostly belonging to Actinobacteria and Firmicutes, while 45 species-level operational taxonomic units distributed in 30 genera were detected by sequencing, with a high diversity of Proteobacteria. This mixed approach allowed the detection of 100% of the genera forming the known core skin Gram-negative microbiota and 43% of the known diversity of Gram-negative genera in human skin. The orphan genera represented 50% of the current skin pan-microbiota. Improved culture conditions allowed the isolation of Roseomonas mucosa, Aurantimonas altamirensis and Agrobacterium tumefaciens strains from healthy skin. For proteobacterial species previously described in the environment, we proposed the existence of skin-specific ecotypes, which might play a role in the fine-tuning of skin homeostasis and opportunistic infections but also act as a shuttle between environmental and human microbial communities. Therefore, skin-associated proteobacteria deserve to be considered in the One-Health concept connecting human health to the health of animals and the environment

Powerful Antioxidant and Pro-Oxidant Properties of Cassia roxburghii DC. Leaves Cultivated in Egypt in Relation to Their Anti-Infectious Activities

Leaf extracts of Cassia roxburghii DC., prepared in petroleum ether, chloroform, ethyl acetate, butanol, and methanol/water (70:30, v/v), were evaluated as antioxidant, pro-oxidant, anti-infectious, and cytotoxic agents. The major metabolite of each extract was identified by chromatographic and spectroscopic means. The redox properties were assessed with a battery of assays, which revealed that the ethyl acetate extract demonstrated an interesting scavenging activity of DPPH and superoxide radicals and an ascorbic acid-like pro-oxidant activity. All the tested extracts showed moderate antiplasmodial activity against a chloroquine-resistant strain of Plasmodium falciparum, by possible disruption of parasite fine redox balance. Cytotoxicity was evaluated against a human breast cancer cell line. The antimicrobial activities of the extracts were estimated against representative bacterial strains (Staphylococcus aureus, Enterococcus hirae, Pseudomonas aeruginosa, Escherichia coli) and fungal species (Candida albicans, Aspergillus niger). The ethylacetate extract possessed the highest redox properties and exhibited the highest antiplasmodial activity; there was no correlation between antibacterial activity and the redox properties of the extracts

Development of an injectable composite for bone regeneration

With the development of minimally invasive surgical techniques, there is a growing interest in the research and development of injectable biomaterials especially for orthopedic applications. In a view to enhance the overall surgery benefits for the patient, the BIOSINJECT project aims at preparing a new generation of mineral-organic composites for bone regeneration exhibiting bioactivity, therapeutic activity and easiness of use to broaden the application domains of the actual bone mineral cements and propose an alternative strategy with regard to their poor resorbability, injectability difficulties and risk of infection. First, a physical-chemical study demonstrated the feasibility of self-setting injectable composites associating calcium carbonate-calcium phosphate cement and polysaccharides (tailor-made or commercial polymer) in the presence or not of an antibacterial agent within the composite formulation. Then, bone cell response and antimicrobial activity of the composite have been evaluated in vitro. Finally, in order to evaluate resorption rate and bone tissue response an animal study has been performed and the histological analysis is still in progress. These multidisciplinary and complementary studies led to promising results in a view of the industrial development of such composite for dental and orthopaedic applications