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Abstract: Lactic acid bacteria (LAB) are naturally present in grapes, musts and wines. During malolactic fermentation, besides the beneficial conversion of L-malic to L-lactic acid, LAB can form also other compounds like biogenic amines (BAs). BAs are formed through decarboxylation of corresponding amino acids, through the action of enzymes. Consumption of food containing BAs can lead to food poisoning such as histamine poisoning. Histamine, the most studied BA, is known to cause headaches, oedema, vomiting. In the last years, BAs associated pathways have been described as strain dependent and not as species dependent. Because of the high variability of microorganisms to decarboxylase amino acids, the detection of bacteria that have the possibility to transform precursor amino acid into BAs is very important in order to estimate the risk of BAs accumulation in wines. Since in previous years during project AGROTUR I we detected the higher BA content in some wines, we decided to focus on the presence of BA-producing LAB in Refošk grapes and wines. Therefore, during AGROTUR II project LAB collection of autochthonous lactic acid bacteria was set-up by isolating LAB from Refošk grapes and wines, originated from the grape growing cross-border region Karst (Slovenia). Over 600 isolates were obtained using MRS medium with added cycloheximide and 2% tomato juice. In parallel, also selective enrichment was performed using MRS medium described above with additionally added 5% ethanol. BA-producing LAB were primarily detected in microtiter-plate format using the decarboxylase screening medium with added amino acids (histidine, lysine, ornithine or tyrosine), which enable us to identify histamine-, cadaverine-, ornithine and tyrosine-producing LAB. Selected representatives from each BA-producing LAB groups were further on confirmed with chromatographic analysis (HPLC) and molecular methods (multiplex PCR method). BA-producing LAB were in majority represented by thyramin-producers, thereafter followed cadaverine-producers, with putrescine and histamine producers being the least presented. This screening of the BA-producing LAB is also incorporated in our on-going accurate selection of LAB starters for potential production of Refošk wines.
Keywords: biogenic amines, lactic acid bacteria, refošk, grape, wine
Published in RUNG: 22.01.2020; Views: 3383; Downloads: 0
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Abstract: EcoLamb assesses the sustainability of diverse European sheep production systems focusing on the ecological footprint, animal welfare aspects and nutrition value of lamb meat. The outcomes of these assessments will be used to understand the potential future barriers that limit the innovative capacity and development of the sector and the opportunities that may provide a future market niche against competitive products from other global markets. Farm solutions that incorporate consumer expectations for animal welfare and meat quality will enhance the competitiveness of Europe's lamb meat sector. The project engages trans-national research and industry stakeholders from 6 countries made up of Germany, Italy, Portugal, Slovenia, Spain and Turkey to analyse on 20 case study farms resource-efficient, competitive and low-carbon lamb production models. Direct linkage between animal welfare, meat quality and pharmaceutical use will also be determined using innovative Precision Farming techniques. The project will produce a toolbox of recommendations for productive sheep farm management, supply chain and marketing on how to improve the acceptability of lamb meat by consumers. Thus, the multidisciplinary approach and the multi-actor involvement of the EU sheep sector will assist in re-designing critical aspects to increase society acceptance and the place of lamb meat in future diets and the outcomes of the project will be used by stakeholders to promote changes in farm management, marketing and processing of meat from sheep. Additionally, results will be used by farm consultants, farmer groups and policy officers to re-design consulting approaches and plan new initiatives to make all aspects of the European sheep industry more sustainable.
Keywords: Sustainability, animal production, lamb, welfare, quality, meat, EcoLamb
Published in RUNG: 26.11.2019; Views: 3219; Downloads: 0
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Abstract: The Human Papillomavirus (HPV) capsid comprises two viral proteins, L1 and L2, with the L2 component being essential to ensure efficient endocytic transport of incoming viral genomes. Several studies have previously reported that L1 and L2 are post-translationally modified, but it is uncertain whether these modifications affect HPV infectious entry. Using a proteomic screen, we identified a highly conserved phospho-acceptor site on the HPV-16 and BPV-1 L2 proteins. The phospho-modification of L2, and its presence in HPV pseudovirions (PsVs), was confirmed using anti-phospho L2-specific antibodies. Mutation of the phospho-acceptor sites of both HPV-16 and BPV-1 L2 resulted in the production of infectious virus particles, with no differences in efficiency of packaging the reporter DNA. However, these mutated PsVs showed marked defects in infectious entry. Further analysis revealed a defect in uncoating, characterized by a delay in the exposure of a conformational epitope on L1 that indicates capsid uncoating. This uncoating defect was accompanied by a delay in the proteolysis of both L1 and L2 in mutated HPV-16 PsVs. Taken together, these studies indicate that phosphorylation of L2 during virus assembly plays an important role in optimal uncoating of virions during infection, suggesting that phosphorylation of the viral capsid proteins contributes to infectious entry.
Keywords: HPV, L2, infection, protein phosphorylation
Published in RUNG: 05.06.2019; Views: 3449; Downloads: 0
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Abstract: Biogenic amines are compounds present in many different foods and beverages (wine, beer, dairy products, fermented vegetables and soy products, fish, etc.). Their presence in foodstuff is a result of a microbial action during storage and ageing. The most important are histamine, tryptamine, β-phenylethylamine and tryptamine, which can induce undesirable physiological effects in humans. They are formed through decarboxylation of corresponding amino acids, through the action of enzymes. Consumption of food containing biogenic amines can lead to food poisoning such as histamine poisoning. Histamine, the most studied biogenic amine, is known to cause headaches, oedema, vomiting, etc. [1]–[4]. Monitoring of the content of biogenic amines in foods is of concern for public health in their relation to the food safety, food spoilage and food intolerance. Because microorganisms are used in food productions as starters and biopreservers, characterization of microorganisms for their ability to produce biogenic amines is equally important. Lactic acid bacteria are often used as biopreservers as they can produce antimicrobial metabolites and antifungal peptides. Some strains can also produce undesirable biogenic amines [5]. In order to use lactic acid bacteria as starters or biopreservers, the selection of strains that would not produce biogenic amines is necessary. When considering studies of biogenic amines in foods, focus should be on developing new or improving analysis methods for biogenic amines detection. Secondly, the connections between microorganisms capable of producing biogenic amines and the content of biogenic amines in foods should be investigated [3]. The most widely technique used for quantification of biogenic amines in foodstuff is liquid chromatography, Alternatively to chromatographic techniques, other techniques such as enzymatic biosensors, ELISA and flow-injection analysis have also been employed. Sensors are interesting due to the fact that they do not require special instrumentations, and there is no need for sample clean-up and derivatization, which are the main drawback of chromatographic methods [4]. Detection of biogenic amines producing lactic bacteria is important due to the concerns for public health and there is a need for the early and rapid detection of such microorganisms. Most of the methods that are used for screening involved the measurement of amino acid-decarboxylase activity, although there were been some methods reported that used differential media and pH indicators. Nowadays, molecular methods are replacing culture methods. Molecular approaches are used to determine the presence or absence of genes responsible for biogenic amines formation. The main advantages of DNA hybridization and PCR methods are speed, simplicity, sensitivity and specificity as they allow detection of targeted genes. Culture independent methods which are based on PCR techniques are now regarded as most suitable methods for screening isolates [5]. [1] A. R. Shalaby, “Significance of biogenic amines to food safety and human health,” Food Res. Int., vol. 29, no. 7, pp. 675–690, Oct. 1996. [2] J. M. Landete, S. Ferrer, and I. Pardo, “Biogenic amine production by lactic acid bacteria, acetic bacteria and yeast isolated from wine,” Food Control, vol. 18, pp. 1569–1574, 2007. [3] F. B. Erim, “Recent analytical approaches to the analysis of biogenic amines in food samples,” TrAC - Trends in Analytical Chemistry, vol. 52. pp. 239–247, 2013. [4] J. L. Ordóñez, A. M. Troncoso, M. D. C. García-Parrilla, and R. M. Callejón, “Recent trends in the determination of biogenic amines in fermented beverages – A review,” Analytica Chimica Acta, vol. 939. pp. 10–25, 2016. [5] R. M. Elsanhoty and M. F. Ramadan, “Genetic screening of biogenic amines production capacity from some lactic acid bacteria strains,” Food Control, vol. 68, pp. 220–228, Oct. 2016.
Keywords: lactic bacteria, biogenic amines
Published in RUNG: 13.12.2018; Views: 3508; Downloads: 0
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Abstract: Humani virusi papiloma (HPV) so povzročitelji najpogostejše spolno prenosljive okužbe, povezani pa so tudi z razvojem raka materničnega vratu. Proteini APOBEC so DNA/RNA editirajoči encimi, ki igrajo ključno vlogo pri prirojenih protivirusnih imunskih odzivih in so vpleteni tako v infekcijo s HPV kot tudi v razvoj rakavih obolenj pri dolgotrajni okužbi s HPV. Glavni cilj magistrskega dela je bil proučiti protivirusno delovanje proteinov APOBEC in določiti tudi ožji nabor proteinov APOBEC, vključenih v protivirusni odziv pri infekciji s HPV. Vpliv proteinov APOBEC na primarno infekcijo smo ugotavljali z uporabo psevdovirusnih delcev (PsV) HPV, v plašču katerih je bil vgrajen reporterski gen za luciferazo. Stopnjo infekcije virusov HPV v gostiteljskih celičnih linijah, transficiranih s proteini hAPOBEC, smo določali posredno preko encimske aktivnosti luciferaze. Ugotovili smo, da izražanje večine proteinov hAPOBEC zniža infektivnost PsV HPV. Izmed proučevanih proteinov hAPOBEC so imeli najmočnejši protivirusni odziv hAID, hA1, hA2, hA3A, hA3B, hA3C in hA3DE, saj so zmanjšali infektivnost PsV HPV-16 za več kot 50 %. Čeprav smo protivirusni učinek proteinov hAPOBEC ugotovili tudi pri dveh kožnih tipih, HPV-2 in HPV-5, je bil le ta značilno višji pri visokorizičnem sluzničnem tipu HPV-16. Mehanizme delovanja proteinov hAPOBEC smo ugotavljali s katalitskimi in nekatalitskimi mutantami proteinov hA3A (E72A) in hA3B (E255Q in E68Q), ki so za razliko od divjih tipov, infektivnost HPV-16 povečale. Mikroskopska analiza znotrajcelične lokalizacije izbranih proteinov hAPOBEC med infekcijo s HPV-16 pa je pokazala, da se 24 ur po infekciji zgodi premik deleža proteina hA3A iz citoplazme v jedro, kar bi lahko vplivalo na potek infekcije. V magistrskem delu smo potrdili prvotno hipotezo, da proteini APOBEC sodelujejo pri protivirusnem odzivu virusov HPV, njihov protivirusni učinek pa je odvisen tako od vrste proteina APOBEC kot tudi od tipa virusa HPV.
Keywords: HPV, proteini APOBEC, protivirusni odziv, infektivnost, znotrajcelična lokalizacija
Published in RUNG: 05.11.2018; Views: 5467; Downloads: 164
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