The activity of the human armpit microbiota triggers the formation of body odor. We used differential 16S rRNA gene (rDNA)-and rRNA-based terminal-restriction fragment length polymorphism fingerprinting in combination with cloning and sequencing to identify active members of the human armpit microbiota. DNA and RNA were isolated from skin scrub samples taken from both armpits of 10 preconditioned, healthy males. The fingerprint profiles indicated pronounced similarities between the armpit microbiota in the right and the left axillae of an individual test person, but larger differences between the axilla microbiota of different individuals. Using 16S rDNA and rRNA sequence data, the majority of peaks in the armpit profiles were assigned to bacteria affiliated with well-known genera of skin bacteria. The relative abundances of all groups were similar among the rDNA and rRNA samples, suggesting that all groups of armpit bacteria were active. Surprisingly, the relative abundance of sequences affiliated with Peptoniphilus sp. was by far and with statistical significance the highest in the rRNA samples of the right armpits. Thus, bacteria affiliated with Peptoniphilus sp. might have been particularly active in the right axillae of the test persons, possibly owing to the handedness of the test persons, which might cause different environmental conditions in the right axillae.

Farnesol was the first quorum-sensing regulator to be found in eukaryotic cells. In Candida albicans, a dimorphic fungal human pathogen, farnesol blocks the yeast-to-filamentous growth transition. Here we show that in Aspergillus niger farnesol acts as an inhibitor of conidiation: Colonies grown on media containing farnesol were unable to develop conidia. Although farnesol treated A. niger cultures exhibited a colony morphology resembling the "fluffy" phenotype of A. nidulans, which is caused by a hyperactive G-protein/cAMP pathway, the intracellular level of cAMP in A. niger mycelia grown in presence of farnesol is greatly diminished. Furthermore, whereas inhibiting adenylyl cyclase led to a farnesol-like effect, the addition of external cAMP inhibited conidiation without causing a "fluffy" phenotype. This suggests that the mechanisms regulating conidiation in A. niger and A. nidulans are different.

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Goal of the present work is to develop an antimicrobial coating that can be applied from an aqueous solution and resists short washing cycles, but can be rinsed off by thorough washing. To this end, a series of star-shaped polystyrene-block-poly(4-vinyl-N-methylpyridinium iodide) polymers are synthesized by anionic polymerization using a core-first approach. The optimal resulting polymers are applied as coatings on glass slides, showing high antimicrobial efficiency against Staphylococcus aureus as well as Escherichia coli. The coatings, characterized by atomic force microscopy and transmission electron microscopy, stay at the surface even after at least 20 flush-like washings with water, and retain their antimicrobial activity.

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