Microalgae are photosynthetic microorganisms that can produce lipids, proteins and carbohydrates in large amounts and within short periods of time and these can be processed into both biofuels and other useful commercial products. Due to this reason microalgae are considered as a potential source of renewable energy; and one of the most important decisions in obtaining oil from microalgae is the choice of species. In this study, the potential of Chlorophyceae species isolated from freshwater and soda lakes in Hungary and Romania (Central Europe) were characterized and evaluated by determining their biomass accumulation, lipid productivity, fatty acid profiles, and biodiesel properties besides protein and carbohydrate productivity. Out of nine strains tested, three accumulated more than 40% dry weight of protein, four accumulated more than 30% dry weight of carbohydrate and the strain Chlorella vulgaris LC8 accumulated high lipid content (42.1% ± 2.6%) with a favorable C16-C18 fatty acid profile (77.4%) as well as suitable biodiesel properties of high cetane number (57.3), low viscosity (4.7 mm 2 /s), lower iodine number (75.18 g I2/100 g), relative cloud point (8.8 °C) and negative cold filter plugging point (−6.5 °C). Hence the OPEN ACCESSEnergies 2015, 8 7503 new strain, Chlorella vulgaris LC8 has potential as a feedstock for the production of excellent quality biodiesel.

The aim of this study was to investigate the genetic diversity of HIV-1 strains circulating in Slovenia. Proviral DNA isolated from peripheral blood mononuclear cells (PBMCs) of 20 randomly selected HIV-1-infected individuals was classified into subtypes by sequence-based phylogenetic analysis of the env (C2V3) and gag (p24) regions of the viral genome. The phylogenetic tree based on env C2V3 sequences showed that 15 of the 20 samples were subtype B, two A1, one F1, one CRF01_AE, and one CRF02_AG. The phylogenetic analysis of the gag gene yielded identical results expect for one sample that had a discordant subtype; it was identified as subtype A1 in the env and AE in the gag region. Our study confirmed that although subtype B predominates, other subtypes and circulating recombinant forms (CRFs) are also present in Slovenia. The high intrasubtype genetic diversity of subtype B sequences suggests a multiple introduction of subtype B strains into Slovenia.

A novel, cheap and easy to use method has been developed to measure low gas yields in bioreactors, based on the principle of bubble counting via digital imaging techniques and pattern recognition. No external hardware control is required for the measurements, and the device can be turned into a multichannel tool without further detector accessories. The method proved to perform outstandingly according to the testing and calibrating measurements against standard gas flow and revealed a short periodicity in the gas yields of two parallel laboratory-scale mesophilic biogas reactors providing well analysable data about them. For exact characterization of the oscillation, the data were converted into Morell wavelet spectra, which showed that every feeding period had a characteristic and similarly shaped wavelet profile, thereby this rhythm must have had an immanent source in the community metabolism, and it was not an artefact.

The aim of the present work was to compare the microbial communities of a mesophilic and a thermophilic pilot scale anaerobe sludge digester. For studying the communities cultivation independent chemotaxonomical methods (RQ and PLFA analyses) and T-RFLP were applied. Microbial communities of the mesophilic and thermophilic pilot digesters showed considerable differences, both concerning the species present, and their abundance. A Methanosarcina sp. dominated the thermophilic, while a Methanosaeta sp. the mesophilic digester among Archaea. Species diversity of Bacteria was reduced in the thermophilic digester. Based on the quinone patterns in both digesters the dominance of sulphate reducing respiratory bacteria could be detected. The PLFA profiles of the digester communities were similar though in minor components characteristic differences were shown. Level of branched chain fatty acids is slightly lower in the thermophilic digester that reports less Gram positive bacteria. The relative ratio of fatty acids characteristic to Enterobacteriaceae, Bacteroidetes and Clostridia shows differences between the two digesters: their importance generally decreased under thermophilic conditions. The sulphate reducer marker (15:1 and 17:1) fatty acids are present in low quantity in both digesters.

The effect of several easily degradable substrates, such as protein, starch and sunflower oil was investigated on the bacterial community of a laboratory-scale biogas model system. Besides measuring gas yield, Denaturing Gradient Gel Electrophoresis (DGGE), Phospholipids Fatty Acid Analysis (PLFA) for Bacteria and T-RFLP analysis of the mcrA gene for Archaea were used. The community of the examined biogas reactors adapted to the new substrates through a robust physiological reaction followed by moderate community abundance shifts. Gas yield data clearly demonstrated the physiological adaptation to substrate shifts. Statistical analysis of DNA and chemotaxonomic biomarkers revealed community abundance changes. Sequences gained from DGGE bands showed the dominance of the phyla Bacteroidetes and the presence of Firmicutes (Clostridia) and Thermotogae. This was supported by the detection of large amounts of branched 15-carbon non-hydroxy fatty acids in PLFA profiles, as common PLFA markers of the Bacteroidetes group. Minor abundance ratios changes were observed in the case of Archaea in accordance with changes of the fed substrates.