The chemical composition of hyssop oil from Bulgaria was determined by gas chromatography with flame ionization detection and gas chromatographyÀmass spectrometry on two different chromatographic columns. The quantity of identified compounds was shown correspond to 97.2% and 98% of the total oil content. Among the detected compounds, cis-pinocamphone (48.98%À50.77%), b-pinene (13.38%À13.54%), trans-pinocamphone (5.78%À5.94%) and b-phellandrene (4.44%À5.17%) were the major compounds. Hyssop oil demonstrated antifungal activity against 52 clinical isolates and reference strains of Candida albicans, Candida glabrata, Candida tropicalis, Candida parapsilosis and Candida krusei. The essential oil characterized with stronger antifungal activity in comparison with pure cis-and trans-pinocamphone, a-and b-pinene and b-phellandrene. Essential oil of Hyssopus officinalis L. from Bulgaria inhibited both fluconazol-sensitive and fluconazol-resistant strains.

Biosorption of Pb(II) ions from a model solution was investigated using Streptomyces fradiae biomass as biosorbent pretreated with sodium hydroxide. The mycelium is a waste product from the biotechnological production of the macrolide antibiotic tylosin in the pharmaceutical industry. The biosorption study was conducted in a batch system with respect to initial pH, initial metal concentration and contact time. For a description of the biosorption equilibrium, Langmuir and Freundlich adsorption models were used. Equilibrium data fitted better to the Langmuir model and the calculated maximum biosorption capacity was 138.88 mg¢g ¡1 at initial pH 5.0, contact time of 120 min, biosorbent dose of 1 g¢dm ¡3and concentration range for the Pb(II) ions from 10 to 200 mg¢dm ¡3 . Pseudo-first and pseudo-second order kinetic models were applied to the experimental data. The results indicated that the Pb(II) uptake process followed the Ho equation. The interference of co-present ions Cu(II) and Zn(II) on the Pb(II) biosorption was also studied. It was determined that at the highest Pb(II) concentration (200 mg¢dm ¡3 ) Cu(II) and Zn(II) caused 27.22% and 24.88% decreasing in Pb(II) uptake, respectively. The obtained results could be useful in prospective applications of chemically modified waste mycelium of S. fradiae as an alternative biosorbent for Pb(II) removal from aqueous solutions.

Microorganisms inhabiting freshwater environments are an integral part of the aquatic ecosystems. Very few data are available regarding the profiles of the microbial communities in the reservoirs in Bulgaria, despite their key role in the biogeochemical processes. In the present study, we provide the first comprehensive metagenomic analysis on the planktonic bacterial diversity of two large and economically important Bulgarian reservoirs (Batak and Tsankov Kamak) using next-generation sequencing of 16S ribosomal RNA gene (16S rRNA). Analysis of the metagenomic amplicon datasets, including quality filtering, clustering of Operational Taxonomic Units and taxonomy assignment revealed that 78.45% of the microbial communities between the two reservoirs were overlapping. The diversity (H) and Pielou's evenness (J) indices declined along the longitudinal axis of both reservoirs. The estimated values for the Shannon diversity index are typically observed in oligotrophic lakes. The microbial communities of both reservoirs were dominated by Proteobacteria, followed by Actinobacteria and Bacteroidetes all comprised over 95% of the relative abundance, regardless of the reservoir's large hydrogeological differences. The bacterioplankton was characterized by high phylogenetic heterogeneity in the taxonomic structure, being distributed among 211 genera. The genera Limnohabitans and Rhodoferax held the absolute predominance, implying their significance in the aquatic food webs. The obtained data can contribute to the better systematic understanding of the microbial diversity of freshwater environments.

We investigate the Feshbach conversion of fermionic atom pairs to condensed bosonic molecules with a microscopic model that accounts for the repulsive interactions among all the particles involved. We find that the conversion efficiency is enhanced by the interaction between bosonic molecules, while it is suppressed by the interactions between fermionic atoms and between atoms and molecules. In the adiabatic limit, the combined effect of these interactions can lead to a ceiling of less than 100% on the conversion efficiency for a narrow Feshbach resonance. Our theory agrees with the recent Rice experiment on 6 Li.

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