1,720,977 research outputs found
¿STUDY OF THE BEHAVIOR OF LACTOCOCCUS LACTIS AND LISTERIA MONOCYTOGENES IN COMPETITION FOR FOOD SAFETY IN DAIRY PRODUCTS¿
Full text linkMicrobial competition is a mechanism that occurs when two or more microbial species compete for ecological niches to support their survival and growth. Different factors can contribute to the outcome of microbial competition, such as molecules exchanged between the competing organisms for the regulation of cell densities and the initial spatial configuration of the microbe–microbe interaction. Specifically, production of compounds that kill or limit the growth of competing strains or species can promote niche monopolization [2]. The released compounds include secondary metabolite antibiotics, bacterial peptides or low-molecular-mass organic compounds. The same happens in food, and it could be possible to explore this 'molecular' communication to improve food safety. In that sense, it is very important to develop tools in the control of bacterial species for a better food safety. The present work focused on the study of microbial competition between Listeria monocytogenes (LM) and Lactococcus lactis (LAC) monitored through proteomics, peptidomics and metabolomics approach. We study the secretome of these two microorganisms (Listeria monocytogenes and Lactococcus lactis) alone and in co-culture. In particular, we studied by proteomic analysis the evaluation of proteins secreted by bacteria through one/two-dimensional electrophoresis coupled to mass spectrometry (MALDI TOF). Furthermore, in order to characterize each secretome, label free Shotgun analysis was conducted using nano UPLC-MS system. Furthermore, the secretome of these microorganisms has been studied through first an untargeted proteomics analysis in vitro, followed by validation directly in a system resuming cheese. The objective of the last part of the project has been the monitoring of bacterial competition between through a combination of microbial Imaging mass spectrometry and LC-MS/MS, in order to investigate the metabolic profile of each bacteria in the interacting microbial colonies. In according with obtained preliminary data (one-dimensional and two-dimensional electrophoresis), new data highlighted, during competition, the higher production by Listeria monocytogenes of moonlighting protein Enolase (C1KY94) and Glucose 6 Phosphate isomerase (Q71X61), of Septation ring formation regulator EzrA (B8DHE7), involved into cell replication in regulatory mechanisms of cell energetics or metabolism and the lower secretion Endopeptidase P60 (P21171), protein associated with the cell surface and involved in the process of invasion. In parallel, L. lactis produced higher amounts of
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Secreted 45 kDa protein and switched from lantibiotic Nisin A production to Nisin Z production. In competition with LM, LAC strain investigated produce higher amounts of Secreted 45 kDa protein with peptidoglycan lytic activity and the selective secretion of Nisin Z probably to improve lantibiotic solubility in less acidic environment. Lastly, IMS analysis revealed several interesting compounds during interaction of microbial colonies. At least six compounds are uniquely expressed during the interaction between LM and LAC. Among these, we focused our attention on three compounds: Cyclo-(Leu-leu), Cyclo-(Phe-Tyr), Cyclo-(L-Phe-L-4-Hyp). These compounds are cyclic peptides, isolated by Lactobacilli, with a biological activity]. In particular, they play an important role in bacterial cell to cell communication. Probably, these peptides have a role in inducing of the transcription of gene coding for Nisine. These results could be useful to setup new molecular strategies in the control of bacterial species for a better food safety
A proteomic approach to investigate the qualitative and quantitative polymorphism of β-lactoglobulin in ovine milk: Inference on gene copy-number variations.
Full text linkThe rationale of this work is based on recent evidences suggesting that: 1) both qualitative and quantitative -lactoglobulin (-LG) polymorphism may be found in bovine milk; 2) quantitative polymorphisms are of- ten the result of expression gradients in multiple cop- ies of a gene; 3) the -LG gene is duplicated in the dog and bovine genome; 4) mammary genes are highly conserved across Mammalia. Thus, an investigation was conducted on ovine -LG polymorphism checking phe- notypic evidence for copy-number variants of -LG in sheep. To the purpose, 206 milk samples were collected, during a small-scale survey within sheep farms breed- ing Southern Italian breeds. PAGIF screening of the samples revealed that approximately 50% individuals exhibited beta-LG polymorphism and 4 different quan- titative patterns, which were characterized in detail by a proteomic approach relying on combined chro- matographic and mass spectrometric techniques. The expected figures based on the expression gradient mod- els were compared with well-established α-globin gene arrangements in sheep. The different phenotypes sug- gest the presence of both duplicate and triplicate BLG haplotypes. The occurrence of a triplicate haplotype was supported by population data. The current study sup- ports the helpfulness of up-to-date proteomics for in- ferring copy number polymorphisms through the char- acterization of the phenotypic expression
Proteomics in Food safety: monitoring competition between Listeria monocytogenes and Lactococcus lactis by Imaging Mass Spectrometry
No full textProteomics profiling of cow adipose tissue in relation to energy balance around calving
No full textThe genetic selection of cows for higher rates of milk production is negatively related to body condition score(BCS) and to reproductive performance. The major problem seems to be related to the increasing gap between milk yield and feed intake which turns in the occurrence of negative energy balance status (NEB). The worst period for cow NEB is experienced after parturition. In this period, proteins and fats are mobilized in order to compensate the energy requirements due to high amounts of milk production. The aim of this study was to analyze the differential proteomics profiling of adipose tissue from cows with different NEB scores. The analysis was performed in a total of 18 samples (3 per group), the first group was composed by cows with low NEB scores and the second group was composed by cows with high NEB scores (hNEB). Both groups were analyzed at three different time points, one month before calving, one week after calving and 16 weeks after calving. Four key proteins involved in adipocyte metabolism were differentially expressed between groups in all time points and, 22 other proteins were differentially expressed when considering each single comparison between the two groups in each time point. These differences highlighted the differentially regulated pathways among hNEB cows. The differential expression of proteins and pathways was consistent one month before calving suggesting that the individual variability in adipose tissue metabolism/mobilization/energy availability could be linked to the different levels of EB among dairy cows
Peptidomics in veterinary science : focus on bovine paratuberculosis
Full text linkBacterial infections represent a serious burden both for animal production and human health (zoonosis). Faster and more reliable diagnosis are mandatory in order to avoid economic losses and antibiotics misuse. The development of new potential diagnostic strategies for the immunodetection of pathogens is closely linked to the discovery of small polypeptides with immunogenic or immunoreactive activity. The candidate peptides used for this purpose must have several properties principally represented by their specificity and their location in the bacterial cell. Both proteomics, peptidomics and bioinformatics represent powerful complementary tools to discover specific immunoreactive peptides useful for diagnosis or vaccine. Peptidomics of Mycobacterium avium subsp. paratuberculosis (MAP) represents a good example of the potential of this discovery-phase. This review reports a comprehensive update of the current scientific knowledge about proteins and peptides of MAP with already documented humoral response. These findings, together with bioinformatics tools available, could be extremely useful to design a better strategy for subclinical bovine paratuberculosis diagnosis. The knowledge provided also represents a reliable example on the workflow to be followed in the direction of the diagnosis of other diseases through a peptidomic approach
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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