The primary aim of the study was to develop and validate an inhouse upscale of Automatic Methane Potential Test System II for studying realtime inocula and realscale substrates in batch, codigestion and enzyme enhanced hydrolysis experiments, in addition to semicontinuous operation of the developed equipment and experiments testing inoculum functional quality. The successful upscale to 5 L enabled comparison of different process configurations in shorter preparation times with acceptable accuracy and highthrough put intended for industrial decision making. The adoption of the same scales, equipment and methodologies in batch and semicontinuous tests mirroring those at full scale biogas plants resulted in matching methane yields between the two laboratory tests and fullscale, confirming thus the increased decision making value of the approach for industrial operations.
COBISS.SI-ID: 3320712
In order to study the effects of nanoparticles (NPs) with different physicochemical properties on cellular viability and structure, Saccharomyces cerevisiae were exposed to different concentrations of TiO2-NPs (1-3 nm), ZnO-NPs ((100 nm), CuO-NPs ((50 nm), Ag-NPs (10 nm) and single-walled carbon nanotubes (SWCNTs). The GreenScreen assay was used to measure cyto- and genotoxicity, and transmission electron microscopy (TEM) used to assess ultrastructure. CuO-NPs were highly cytotoxic, reducing the cell density by 80% at 9 cm^2 /ml, and inducing lipid droplet formation. Cells exposed to Ag-NPs (19 cm(2)/ml) and TiO2-NPs (147 cm^2 /ml) contained dark deposits in intracellular vacuoles, the cell wall and vesicles, and reduced cell density (40 and 30%, respectively). ZnO-NPs (8 cm^2 /ml) caused an increase in the size of intracellular vacuoles, despite not being cytotoxic. SWCNTs did not cause cytotoxicity or significant alterations in ultrastructure, despite high oxidative potential. Two genotoxicity assays, GreenScreen and the comet assay, produced different results and the authors discuss the reasons for this discrepancy. Classical assays of toxicity may not be the most suitable for studying the effects of NPs in cellular systems, and the simultaneous assessment of other measures of the state of cells, such as TEM are highly recommended.
COBISS.SI-ID: 3220104
The aim of the study was to access the effects of hop cones (Humulus lupulus L.) from two varieties Aurora and Dana, differing in their alpha- and beta-acid contents, on rumen microbial activity measured with in vitro gas production kinetics and short-chain fatty acids (SCFA) production. Hop cones were added to the total mixed dairy cow ration (CONT) in concentrations simulating a cow’s daily intake of 50, 100 and 200 g of hop cones - the concentrations of hop cones expressed on a substrate basis were 43, 82 and 153 mg/g of substrate. Substrates were anaerobically incubated in buffered rumen fluid and gas production kinetic parameters were determined by fitting data with the Gompertz model. Gas produced after 24 hours (Gas24), maximum fermentation rate (MFR) and time of maximum fermentation rate (TMFR) were calculated from estimated gas production kinetic parameters. After 24 hours of incubation the fermentation liquids of each substrate were taken for the determination of short-chain fatty acids. Increasing the hop cone concentration decreased the total potential gas production, Gas24, MFR and shortened TMFR. The highest hop cone concentration decreased acetic and butyric acid and total SCFA production after 24 hours of incubation, but not propionic acid production, resulting in a decreased ratio between acetic and propionic acid.
COBISS.SI-ID: 658316
The purpose of this study was to discover differences in the human fecal microbiota composition driven by long term omnivore vs. vegan/lactovegetarian dietary pattern. In addition the possible association of demographic characteristics and dietary habits with the fecal microbiota was examined. The study was conducted on a Slovenian population comprising 31 vegetarian participants (11 lacto-vegetarians and 20 vegans) and 29 omnivore participants. The results of the analyses of fecal microbiome showed that vegetarian diet was associated with higher ratio of Bacteroides-Prevotella, Bacteroides thetaiotaomicron, Clostridium clostridioforme and Faecalibacterium prausnitzii, but with lower ratio of Clostridium cluster XIVa. Real-time PCR also showed a higher concentration and ratio of Enterobacteriaceae (16S rDNA copies/g and %) in female participants (p(0.05 and p(0.01) and decrease of Bifidobacterium with age (p(0.01). DGGE analysis of the 16S rRNA V3 region showed that relative quantity of DGGE bands from certain bacterial groups was lower (Bifidobacterium, Streptococus ,Collinsella and Lachnospiraceae) or higher (Subdoligranulum) among vegetarians, indicating the association of dietary type with bacterial community composition. Sequencing of selected DGGE bands revealed the presence of common representatives of fecal microbiota: Bacteroides, Eubacterium, Faecalibacterium, Ruminococcaceae, Bifidobacterium and Lachnospiraceae. Up to 4% of variance in microbial community analysed by DGGE could be explained by the vegetarian type of diet. In conclusion, long term vegetarian diet influenced the fecal microbiota composition. Consumption of foods of animal origin (eggs, red meat, white meat, milk, yoghurt, other dairy products, fish and seafood) and vegetarian type of diet explained the largest share of variance in microbial community structure. Fecal microbiota composition was also associated with participants’ age, gender and body mass.
COBISS.SI-ID: 3303048
The genome of Lactobacillus gasseri K7, isolated from baby's faeces, contains gene regions encoding two-component bacteriocins gassericin K7 A [GenBank EF392861] and gassericin K7 B [GenBank AY307382]. The strain has been known to exhibit bacteriocin activity in vitro, however, no data exist on the expression of particular genes of bacteriocins' operons or on the activity of individual components of this bacteriocin complex, which has not been isolated so far. The objectives of this study were to examine bacteriocin genes' expression during the growth of L. gasseri K7 and to isolate individual components in order to reveal the contribution of individual peptides to the overall bacteriocin activity. All 8 target genes were expressed during exponential phase of growth in MRS broth. Mass spectrometry analysis revealed that the amino acid sequence of isolated peptide matched the deduced amino acid sequence of putative active peptide of gassericin K7 B (Gas K7 B_AcP) and GatX, a complementary peptide of gassericin T, previously supposed to have no antimicrobial activity. The isolated peptide showed a broad spectrum of bacteriocin activity. Furthermore, the isolation protocol developed in this study will enable to obtain a considerable amount of purified bacteriocins needed for further investigation of their functionality.
COBISS.SI-ID: 3393672