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  • Chamlagain, Bhawani Shankar (2011)
    Dynamics of raw milk associated bacteria during cold storage of raw milk and their antibiotic resistance was reviewed, with focus on psychrotrophic bacteria. This study aimed to investigate the significance of cold storage of raw milk on antibiotic-resistant bacterial population and analyse the antibiotic resistance of the Gram-negative antibiotic-resistant psychrotrophic bacteria isolated from the cold-stored raw milk samples. Twenty-four raw milk samples, six at a time, were obtained from lorries that collected milk from Finnish farms and were stored at 4°C/4 d, 6°C/3 d and 6°C/4 d. Antibiotics representing four classes of antibiotics (gentamicin, ceftazidime, levofloxacin and trimethoprim-sulfamethoxazole) were used to determine the antibiotic resistance of mesophilic and psychrotrophic bacteria during the storage period. A representative number of antibiotic-resistant Gram-negative isolates retrieved from the cold-stored raw milk samples were identified by the phenotypic API 20 NE system and a few isolates by the 16S rDNA gene sequencing. Some of the isolates were further evaluated for their antibiotic resistance by the ATB PSE 5 and HiComb system. The initial average mesophilic counts were found below 105 CFU/mL, suggesting that the raw milk samples were of good quality. However, the mesophilic and psychrotrophic population increased when stored at 4°C/4 d, 6°C/3 d and 6°C/4 d. Gentamicin- and levofloxacin-resistant bacteria increased moderately (P < 0.05) while there was a considerable rise (P < 0.05) of ceftazidime- and trimethoprim-sulfamethoxazole-resistant population during the cold storage. Of the 50.9 % (28) of resistant isolates (total 55) identified by API 20 NE, the majority were Sphingomonas paucimobilis (8), Pseudomonas putida (5), Sphingobacterium spiritivorum (3) and Acinetobacter baumanii (2). The analysis by ATB PSE 5 system suggested that 57.1% of the isolates (total 49) were multiresistant. This study showed that the dairy environment harbours multidrug-resistant Gramnegative psychrotrophic bacteria and the cold chain of raw milk storage amplifies the antibioticresistant psychrotrophic bacterial population.
  • Blom, Titta S. (Helsingin yliopisto, 2003)
  • Vainio, Ulla (Helsingin yliopisto, 2007)
    Wood is an important material for the construction and pulping industries. Using x-ray diffraction the microfibril angle of Sitka spruce wood was studied in the first part of this thesis. Sitka spruce (Picea sitchensis [Bong.] Carr.) is native to the west coast of North America, but due to its fast growth rate, it has also been imported to Europe. So far, its nanometre scale properties have not been systematically characterised. In this thesis the microfibril angle of Sitka spruce was shown to depend significantly on the origin of the tree in the first annual rings near the pith. Wood can be further processed to separate lignin from cellulose and hemicelluloses. Solid cellulose can act as a reducer for metal ions and it is also a porous support for nanoparticles. By chemically reducing nickel or copper in the solid cellulose support it is possible to get small nanoparticles on the surfaces of the cellulose fibres. Cellulose supported metal nanoparticles can potentially be used as environmentally friendly catalysts in organic chemistry reactions. In this thesis the size of the nickel and copper containing nanoparticles were studied using anomalous small-angle x-ray scattering and wide-angle x-ray scattering. The anomalous small-angle x-ray scattering experiments showed that the crystallite size of the copper oxide nanoparticles was the same as the size of the nanoparticles, so the nanoparticles were single crystals. The nickel containing nanoparticles were amorphous, but crystallised upon heating. The size of the nanoparticles was observed to be smaller when the reduction of nickel was done in aqueous ammonium hydrate medium compared to reduction made in aqueous solution. Lignin is typically seen as the side-product of wood industries. Lignin is the second most abundant natural polymer on Earth, and it possesses potential to be a useful material for many purposes in addition to being an energy source for the pulp mills. In this thesis, the morphology of several lignins, which were produced by different separation methods from wood, was studied using small-angle and ultra small-angle x-ray scattering. It was shown that the fractal model previously proposed for the lignin structure does not apply to most of the extracted lignin types. The only lignin to which the fractal model could be applied was kraft lignin. In aqueous solutions the average shape of the low molar mass kraft lignin particles was observed to be elongated and flat. The average shape does not necessarily correspond to the shape of the individual particles because of the polydispersity of the fraction and due to selfassociation of the particles. Lignins, and especially lignosulfonate, have many uses as dispersants, binders and emulsion stabilisers. In this thesis work the selfassociation of low molar mass lignosulfonate macromolecules was observed using small-angle x-ray scattering. By taking into account the polydispersity of the studied lignosulfonate fraction, the shape of the lignosulfonate particles was determined to be flat by fitting an oblate ellipsoidal model to the scattering intensity.
  • Koskinen, Kaisa (Helsingin yliopisto, 2013)
    Microbes are essential for all life on Earth. They are found in all viable habitats from deep sea sediments and bedrock to high up in the atmosphere with a variety that exceeds by far the eukaryotic diversity. Ecosystem services provided by microorganisms, such as degradation of organic material and mediation of biogeochemical cycles are fundamentally important for the whole biosphere and its inhabitants. Microbes also form symbiotic relationships with multicellular organisms, and play important roles in nutrition and disease. Recent developments in molecular techniques, especially the next generation sequencing technologies and microarray applications, have opened new possibilities in studying diverse microbial communities. In this thesis, the aim was to determine the diversity and community structure of environmental samples collected from the northern Baltic Sea water column and anaerobic digestion reactor, and to assess how the prevailing abiotic factors affect the microbial community structure. We applied 16S rRNA and ITS gene amplicon sequencing method with 454 sequencing technology to form a detailed taxonomic description of studied communities. The produced sequence data was further utilised in designing probes for a new padlock probe based ligation detection reaction (LDR) microarray that could be employed for specific and sensitive taxonomic identification of microbial groups in diverse communities. The functionality, specificity and sensitivity of the microarray were assessed using artificial and real environmental samples. Additionally, selected amplicon sequencing data analysis methods were compared in order to discover which algorithms work most reliably. In this subproject, we aimed to clarify how significantly the selected analysis methods, specifically denoising and clustering algorithms, affect the results and how comparable the results derived from different analysis pipelines are. Amplicon sequencing revealed diverse microbial communities in the northern Baltic Sea water column and anaerobic digestion reactor. The pelagic bacterial communities in the northern Baltic Sea were strongly stratified, with aerobic Bacteria such as Pseudomonas and Flavobacterium dominating in the surface layer and Oleispira and sulfate-reducing bacteria in the anoxic deep waters. Based on the sequence data the diversity was assessed one order of magnitude less diverse compared to Atlantic and Pacific ocean bacterial communities. The anaerobic digestion reactor communities were dominated by Bacteria belonging to phyla Bacteroidetes, Firmicutes and Thermotogae and methanogenic Archaea, all essential and typical degraders in anaerobic digestion. The process also supported a diverse fungal community of phyla Ascomycota and Basidiomycota, including several taxa capable of degrading organic material in anaerobic conditions. The LDR microarray technology proved sensitive, specific and semiquantitative method for identifying microbes in diverse communities. The proof of principle tests and experiments with real environmental samples showed that if the probes are designed carefully, the detection is comparable to qPCR and amplicon sequencing. The detection limit was 0.01 fmol/µl/template. Data analysis method comparisons revealed prominent differences in observed operational taxonomic units and relative abundance of identified taxa. The majority of tested methods assessed the species richness too high. Using a functioning denoising method evened out the differences in the number of observed OTUs caused by various clustering algorithms. The ability to filter out the spurious taxa produced by amplification and sequencing, but still retain all the real diversity varied between methods. This study shows both the potential and the challenges in the use of amplicon sequencing and microarray technologies in studying diverse microbial communities. The results indicate that the padlock based LDR microarray can be designed for very accurate and sensitive identification of microbial groups of interest. The data suggest that amplicon sequencing is a powerful tool in identifying microbes and assessing the diversity but distinguishing between spurious and true community members remain a challenge. There is still work to be done in the development and application of data analysis tools.
  • Sarén, Matti-Paavo (Helsingin yliopisto, 2006)
    In recent years there has been growing interest in selecting suitable wood raw material to increase end product quality and to increase the efficiency of industrial processes. Genetic background and growing conditions are known to affect properties of growing trees, but only a few parameters reflecting wood quality, such as volume and density can be measured on an industrial scale. Therefore research on cellular level structures of trees grown in different conditions is needed to increase understanding of the growth process of trees leading to desired wood properties. In this work the cellular and cell wall structures of wood were studied. Parameters, such as the mean microfibril angle (MFA), the spiral grain angles, the fibre length, the tracheid cell wall thickness and the cross-sectional shape of the tracheid, were determined as a function of distance from the pith towards the bark and mutual dependencies of these parameters were discussed. Samples from fast-grown trees, which belong to a same clone, grown in fertile soil and also from fertilised trees were measured. It was found that in fast-grown trees the mean MFA decreased more gradually from the pith to the bark than in reference stems. In fast-grown samples cells were shorter, more thin-walled and their cross-sections were rounder than in slower-grown reference trees. Increased growth rate was found to cause an increase in spiral grain variation both within and between annual rings. Furthermore, methods for determination of the mean MFA using x-ray diffraction were evaluated. Several experimental arrangements including the synchrotron radiation based microdiffraction were compared. For evaluation of the data analysis procedures a general form for diffraction conditions in terms of angles describing the fibre orientation and the shape of the cell was derived. The effects of these parameters on the obtained microfibril angles were discussed. The use of symmetrical transmission geometry and tangentially cut samples gave the most reliable MFA values.
  • Rantakari, Anssi (Helsingin yliopisto, 2005)
  • Holvikari, Kira (2015)
    MRP2 on ABC-kuljetinproteiineihin kuuluva effluxi-kuljetinproteiini, joka esiintyy solukalvojen apikaalipuolella pääasiassa maksassa, maha-suolikanavan enterosyyteissä, munuaisissa ja keuhkoissa. Tämä kuljetinproteiini on yhdistetty ilmiöön (lääkeresistenssi, multidrug resistance), jossa lääkkeen imeytyminen vähenee kuljetinproteiinin ansiosta tämän kuljettaessa lääkeainetta ulos solusta. Tämän ilmiön estämiseksi etsitään voimakkaita kuljetinproteiinin estäjiä ja substraatteja. On esitetty, että lukuisat flavonoidit ovat inhibiittoreita MRP2-kuljetinproteiiniille, mutta tutkimus flavonoideihin liittyen jatkuu. Toinen ryhmä aineita, joista on esitetty estäjiä MRP2 kuljetinproteiinille, on farmaseuttiset apuaineet. Molemmat, sekä flavonoidit että apuaineet, ovat aineita, joita tutkitaan jatkuvasti lääke-yhteisvaikutuksiin liittyen. Nykyään voidaankin arvioida, että apuaineet eivät ole täysin reagoimattomia aineita elimistössä, kuten aiemmin on ajateltu. Tällä hetkellä MRP2-kuljetinproteiinin tieteellinen tutkimus keskittyy in vitro tutkimuksiin. Tämän erikoistyön kokeellisessa osuudessa tutkitaan luonnonaineiden ja farmaseuttisten apuaineiden vaikutuksia MRP2-kuljetinproteiiniin vesikkelikuljetusanalyysillä (VT-analyysi), käyttäen MRP2-Spodoptera frugiperda 9 (Sf9)- membraanivesikkeleitä ja 5(6)-karboksi-2,′7′-diklorofluoresiini (CDCF)-yhdistettä koettimena. Ajatuksena on löytää MRP2 kuljetinproteiinin estäjiä ja substraatteja. Yhteensä 157 ainetta seulotaan käyttäen tätä in vitro metodia ja näistä löytyvät potentiaaliset aineet tutkitaan tarkemmin suorittamalla IC50- ja Ki-määrityksiä. Potentiaalisia aineita tutkitaan myös kahdella eri metodilla, dynaamisella valo sironnalla (Dynamic light scattering, DLS) ja nefelometrillä, jotta voidaan varmistua täydellisestä aineiden liukenemisesta ja siitä että kuljetinproteiinin esto ei aiheudu mikrokeräytymien johdosta. Lopuksi potentiaaliset MRP2 substraatit tutkitaan käyttäen VTanalyysiä, jossa on detektorina nestekromatografi-massa spetrometri (LC-MS). 157 yhdisteestä löytyi 19 (12%) ainetta, jotka osoittivat muutoksia CDCF:n kuljetuksessa. 6 ainetta stimuloi (CDCF:n kuljetus kasvoi ≥ 150%) ja 13 ainetta inhibioi MRP2 kuljetusta (CDCF kuljetus laski ≦ 50%). IC50 määritys tehtiin 12 aineelle, joille saattiin seuraavat tulokset: Ellaghappo 10.4 μM, gossypiini 17.4 μM, moriinidihydraatti 19.4 μM, myrisetiini 27.1 μM, nordihydroguaiareettihappo (NDGA) 36.2 μM, oktyyligallaatti 20.3 μM, silybiini 52.3 μM, pluronic ®F98 6.9 μM, lutrol F127 ∼ 8.2 μM and tanniinihappo 1.99 μM. Ki määritys tehtiin kolmelle aineelle, joista tuloksiksi saatiin seuraavaa: Myrisetiini 42.9 ± 47.4 μM, gossypiini 19.4 ± 12.5 μM and tanniinihappo 0.0538 ± 0.0398 μM. Ki määrityksen yhteydessä myös inhibition tyyppi määritettiin: Kilpaileva inhibitio; tanniinihappo ja gossypiini sekä kilpailematon inhibitio; myrisetiini. Mikrokeräytymien ja liukoisuuden mittauksissa ei esiintynyt merkittäviä keräytymiä ja inhibitio tällä mekanismilla voidaan sulkea pois. Mikrokertymien ja liukoisuuden mittaaminen tulisi kuitenkin optimoida, luotettavien tulosten saamiseksi. Stimulaattorit baikaleiini, baikaliini, digitoksigeniini sekä inhibiittorit myrisetiini, gossypiini ja tanniinihappo tutkittiin lopuksi LC-MS metodilla. Tuloksista käy ilmi, että gossypiini, jonka +ATP tulos oli suurempi kuin -ATP tulos 50μM:n konsentraatiossa, voisi olla MRP2-substraatti. Yhteenvetona, gossypiinilla on kilpailevaa inhibitiota MRP2-kuljetinproteiinia kohtaan ja näyttää siltä, että se olisi myös MRP2-substraatti. Nämä tulokset on kuitenkin varmistettava jatkotutkimuksin.
  • Hukkinen, Maria (2010)
    Tupakointitutkimukset keskittyvät perinteisesti säännöllisesti tai runsaasti tupakoiviin. Koska ei ole osoitettu mitään terveyden kannalta haitattoman tupakoinnin rajaa, määrältään vähäisenkin tupakoinnin tutkiminen on tärkeää. Tutkielman tavoitteina oli analysoida päivittäin 1-4 savuketta polttavien ominaispiirteitä, tupakointitottumusten pysyvyyttä sekä tupakointitavan muutosta ennustavia tekijöitä. Tutkimuksessa käytettiin vuosina 1975, 1981 ja 1990 kerätyn suomalaisen kaksoskohorttitutkimuksen kyselyaineistoa. Vuoden 1975 aineistossa oli 9 940 päivittäistupakoitsijaa, joista 8% poltti alle 5 ja 20% vähintään 20 savuketta päivässä. Tutkimuksessa verrattiin päivittäin vähän ja paljon polttavien ominaispiirteitä. Vähän tupakoivat olivat todennäköisemmin naisia, yksin eläviä, liikunnallisia, korkeammin koulutettuja, elämäänsä tyytyväisiä ja vähemmän stressaantuneita kuin runsaasti polttavat. Pienempi osuus vähemmän tupakoivista käytti runsaasti kahvia ja alkoholia tai tupakoidessaan hengitti savua keuhkoihin. Pitkittäistarkastelussa ikä, koulutusaste, siviilisäädyn muutos ja alkoholin käyttö ennustivat tupakointitapojen muuttumista. Yksilötasolla vähäinen tupakointi oli usein väliaikaista: seuranta-aikana valtaosa lopetti tupakoinnin tai lisäsi savukemäärää. Väestötasolla vähän tupakoivien osuus pysytteli samana: tupakoinnin aloittajia, vähentäjiä sekä aiemmin lopettaneita mutta uudelleen aloittaneita siirtyi tähän ryhmään.
  • Sainio, Janne (2011)
    Lactose is probably the most used tablet excipient in the field of pharmacy. Although lactose is thoroughly characterized and available in many different forms there is a need to find a replacer for lactose as a filler/binder in tablet formulations because it has some downsides. Melibiose is a relatively unknown disaccharide that has not been thoroughly characterized and not previously used as an excipient in tablets. Structurally melibiose is close to lactose as it is also formed from the same two monosaccharides, glucose and galactose. Aim of this research is to characterize and to study physicochemical properties of melibiose. Also the potential of melibiose to be used as pharmaceutical tablet excipient, even as a substitute for lactose is evaluated. Current knowledge about fundamentals of tableting and methods for determinating of deformation behavior and tabletability are reviewed. In this research Raman spectroscopy, X-ray powder diffraction (XRPD), near-infrared spectroscopy (NIR) and Fourier-transform infrared spectroscopy (FT-IR) were used to study differences between two melibiose batches purchased from two suppliers. In NIR and FT-IR measurements no difference between materials could be observed. XPRD and Raman however found differences between the two melibiose batches. Also the effects of moisture content and heating to material properties were studied and moisture content of materials seems to cause some differences. Thermal analytical methods, differential scanning calorimetry (DSC) and thermogravimetry (TG) were used to study thermal behaviour of melibiose and difference between materials was found. Other melibiose batch contains residual water which evaporates at higher temperatures causing the differences in thermal behaviour. Scanning electron microscopy images were used to evaluate particle size, particle shape and morphology. Bulk, tapped and true densities and flow properties of melibiose was measured. Particle size of the melibiose batches are quite different resulting causing differences in the flowability. Instrumented tableting machine and compression simulator were used to evaluate tableting properties of melbiose compared to α-lactose monohydrate. Heckel analysis and strain-rate sensitivity index were used to determine deformation mechanism of melibiose monohydrate in relation to α–lactose monohydrate during compaction. Melibiose seems to have similar deformation behaviour than α-lactose monohydrate. Melibiose is most likely fragmenting material. Melibiose has better compactibility than α – lactose monohydrate as it produces tablets with higher tensile strength with similar compression pressures. More compression studies are however needed to confirm these results because limitations of this study.
  • Tsitko, Irina (Helsingin yliopisto, 2007)
    Species of the genera Rhodococcus, Gordonia and Mycobacterium are known as degraders of recalcitrant pollutants. These bacteria are good survivors in harsh environments. Due to such properties these organisms are able to occupy a wide range of environmental niches. The members of these taxa have been suggested as tools for biotechnical applications such as bioremediation and biosynthesis. At the same time several of the species are known as opportunistic human pathogens. Therefore, the detailed characterization of any isolate that has potential for biotechnological applications is very important. This thesis deals with several corynebacterial strains originating from different polluted environments: soil, water-damaged indoor walls, and drinking water distribution systems. A polyphasic taxonomic approach was applied for characterization of the isolates. We found that the strains degrading monoaromatic compounds belonged to Rhodococcus opacus, a species that has not been associated with any health problem. The taxonomic position of strain B293, used for many years in degradation research under different names, was clarified. We assigned it to the species Gordonia polyisoprenivorans. This species is classified under European Biohazard grouping 1, meaning that it is not considered a health hazard for humans. However, there are reports of catheter-associated bacteraemia caused by G. polyisoprenivorans. Our results suggested that the ability of the organism to grow on phthalate esters, used as softeners in medical plastics, may be associated with the colonization of catheters and other devices. In this thesis Mycobacterium lentiflavum, a new emerging opportunistic human pathogen, was isolated from biofilms growing in public drinking water distribution systems. Our report on isolation of M. lentiflavum from water supplies is the second report on this species from drinking water systems, which may thus constitute a reservoir of M. lentiflavum. Automated riboprinting was evaluated for its applicability in rapidly identifying environmental mycobacteria. The technique was found useful in the characterization of several species of rapidly and slowly growing environmental mycobacteria. The second aspect of this thesis refers to characterization of the degradation and tolerance power of several R. opacus, M. murale and G. polyisoprenivorans strains. R. opacus GM-14 utilizes a wide range of aromatic substrates, including benzene, 15 different halobenzenes, 18 phenols and 7 benzoates. This study revealed the high tolerance of R. opacus strains toward toxic hydrophobic compounds. R. opacus GM-14 grew in mineral medium to which benzene or monochlorobenzene was added in amounts of 13 or 3 g l-1, respectively. R. opacus GM-29 utilized toluene and benzene for growth. Strain GM-29 grew in mineral medium with 7 g l-1 of liquid toluene or benzene as the sole carbon source, corresponding to aqueous concentrations of 470 and 650 mg l-1, respectively. Most organic solvents, such as toluene and benzene, due to their high level of hydrophobicity, pass through the bacterial membrane, causing its disintegration. In this thesis the mechanisms of adaptation of rhodococci to toxic hydrophobic compounds were investigated. The rhodococcal strains increased the level of saturation of their cellular fatty acids in response to challenge with phenol, chlorophenol, benzene, chlorobenzene or toluene. The results indicated that increase in the saturation level of cellular fatty acids, particularly that in tuberculostearic acid, is part of the adaptation mechanism of strains GM-14 and GM-29 to the presence of toxic hydrophobic compounds.
  • Gonzalez, Manuel (2012)
    Campylobacter Spp are recognized as a major cause of bacterial food-borne gastroenteritis worldwide, with Campylobacter jejuni and Campylobacter coli being the most common species isolated in human infections (WHO, 2011). The number of registered cases of human campylobacteriosis in Finland has ranged from 3,796 cases in 2001 to 4,231 cases in 2011. The reported incidence in Finland in the last 10 years is higher than the European Union average. In order to compare human, chicken and cattle C. jejuni isolates, the presence or absence of four nonubiquitous genes were determined so that they could be associated with the source of the isolate. First, we tested the presence of dmsA, which encodes a subunit of the putative tripartite anaerobic dimethyl sulfoxide oxidoreductase (DMSO/trimethylamine N-oxide reductase). Second, we detected cj1585c, which encodes another oxidoreductase. Third, the serine protease gene cjj81176-1367/1371 was isolated. Fourth, γ-glutamyl-transpeptidase gene ggt was detected. We ascertained that ggt and dmsA are present more frequently in isolates obtained from humans and chickens, whereas cjj81176-1367/1371 and cj1585c are the most common in bovine isolates. Campylobacter jejuni is able to survive in different environments and in a wide range of temperatures. The study of C. jejuni inactivation in minced chicken meat and dug well water ascertain that the Weibull model could be applied optimally to the data to build a reliable prediction model for the survival of this microorganism as a function of temperature. The longest survival time found for C. jejuni in minced meat chicken was at the storage temperature of -20°C, and that of dug well water was at 4°C. We analyzed the effect of different seasoning as dry marinade combinations on accelerating the reduction of C. jejuni counts on chicken drumsticks and observed a decrease of more than 1 log CFU/g. In addition, our results showed that using some fractions of potato protein in combination with food additives and sodium lactate obtained inactivation levels in excess than 1.66 log CFU/g. The most important C. jejuni counts reductions were always obtained within the first hours after the application of the seasoning combinations onto the chicken meat.
  • Pesonen, Antto (Helsingin yliopisto, 2012)
    The increased use of liquid biofuels has created a need for an accurate and a reliable technique for determining blend ratios of biofuel and fossil fuel due to technical reasons related to car engines and due to legislative reasons. The true portion of biological carbon in a fuel can be determined reliably only by radiocarbon measurement. Radiocarbon is created in upper atmosphere by cosmic radiation and is transferred to flora and fauna via photosynthesis. When an organism dies, the radiocarbon in its body starts do decay. Because the half-life of radiocarbon is very long and because biofuels are manufactured from relatively young feedstock materials, it is possible to calculate the biofraction of a fuel sample by determining its radiocarbon contents. The most popular techniques for determining this are, to date, accelerator mass spectrometry and liquid scintillation counting. Liquid scintillation counting is cheaper and easier to use, but in low concentrations the accuracy is not as good. In addition, the technique has the drawback of quenching effects. Accelerator mass spectrometry is the most accurate method, but the disadvantages are the price and size of the equipment and labor-intensive sample preparation process, which can take several days. In addition to the radioanalytical techniques, the biofractions of biofuels have been determined by infrared, Raman, nuclear magnetic resonance, X-ray and fluorescence spectroscopy and by gas and liquid chromatography, but these techniques have more limited applicability. In these techniques, the determination is usually based on direct or indirect detection of fatty acid methyl ester groups. However, the newer generation biofuels do not anymore contain these groups and their chemical composition is similar to fossil fuels. In addition, by using these techniques one cannot determine e.g. whether the ethanol in petrol blend is in fact manufactured from biological or fossil sources. In the experimental section of the thesis an elemental analyzer -based sample preparation method was developed, by which the time spent on sample preparation for accelerator mass spectrometer was decreased when compared to previous method, described by standard ASTM D6866-10. The biodiesel samples were combusted in the elemental analyzer and the carbon dioxide collected cryogenically. The carbon dioxide was reduced to graphite and their radiocarbon contents was measured by accelerator mass spectrometry. In addition, the results from elemental analyzer method were compared to previous results by closed-tube-combustion method. It was noticed that the elemental analyzer method was more accurate, faster and easier to use.