Browsing by Subject "adhesion"

Sort by: Order: Results:

Now showing items 1-17 of 17
  • Guenther, Carla; Faisal, Imrul; Uotila, Liisa; Llort Asens, Marc; Harjunpää, Heidi; Savinko, Terhi; Öhman, Tiina; Yao, Sean; Moser, Markus; Morris, Stephan W.; Tojkander, Sari; Fagerholm, Susanna (2019)
    beta2-integrins are essential for immune system function because they mediate immune cell adhesion and signaling. Consequently, a loss of beta2-integrin expression or function causes the immunodeficiency disorders, Leukocyte Adhesion Deficiency (LAD) type I and III. LAD-III is caused by mutations in an important integrin regulator, kindlin-3, but exactly how kindlin-3 regulates leukocyte adhesion has remained incompletely understood. Here we demonstrate that mutation of the kindlin-3 binding site in the b2-integrin (TTT/AAA-b2-integrin knock-in mouse/KI) abolishes activation of the actin-regulated myocardin related transcription factor A/serum response factor (MRTF-A/SRF) signaling pathway in dendritic cells and MRTF-A/SRF-dependent gene expression. We show that Ras homolog gene family, member A (RhoA) activation and filamentous-actin (F-actin) polymerization is abolished in murine TTT/AAA-b2-integrin KI dendritic cells, which leads to a failure ofMRTF-A to localize to the cell nucleus to coactivate genes together with SRF. In addition, we show that dendritic cell gene expression, adhesion and integrin-mediated traction forces on ligand coated surfaces is dependent on the MRTF-A/SRF signaling pathway. The participation of b2-integrin and kindlin-3-mediated cell adhesion in the regulation of the ubiquitous MRTF-A/SRF signaling pathway in immune cells may help explain the role of b2-integrin and kindlin-3 in integrin-mediated gene regulation and immune system function.
  • Yu, Xia; Åvall-Jääskeläinen, Silja; Koort, Joanna; Lindholm, Agneta; Rintahaka, Johanna; von Ossowski, Ingemar; Palva, Airi; Hynönen, Ulla (2017)
    Lactobacillus ruminis, an autochthonous member of the gastrointestinal microbiota of humans and many animals, is a less characterized but interesting species for many reasons, including its intestinal prevalence and possible positive roles in host-microbe crosstalk. In this study, we isolated a novel L. ruminis strain (GRL 1172) from porcine feces and analyzed its functional characteristics and niche adaptation factors in parallel with those of three other L. ruminis strains (a human isolate, ATCC 25644, and two bovine isolates, ATCC 27780 and ATCC 27781). All the strains adhered to fibronectin, type I collagen, and human colorectal adenocarcinoma cells (HT-29), but poorly to type IV collagen, porcine intestinal epithelial cells (IPEC-1), and human colon adenocarcinoma cells (Caco-2). In competition assays, all the strains were able to inhibit the adhesion of Yersinia enterocolitica and enterotoxigenic Escherichia coli (ETEC, F4(+)) to fibronectin, type I; collagen, IPEC-1, and Caco-2 cells, and the inhibition rates tended to be higher than in exclusion assays. The culture supernatants of the tested strains inhibited the growth of six selected pathogens to varying extents. The inhibition was solely based on the low pH resulting from acid production during growth. All four L. ruminis strains supported the barrier function maintenance of Caco-2 cells, as shown by the modest increase in trans-epithelial electrical resistance and the prevention of dextran diffusion during co-incubation. However, the strains could not prevent the barrier damage caused by ETEC in the Caco-2 cell model. All the tested strains and their culture supernatants were able to provoke Toll-like receptor (TLR) 2-mediated NF-kappa B activation and IL-8 production in vitro to varying degrees. The induction of TLR5 signaling revealed that flagella were expressed by all the tested strains, but to different extents. Flagella and pili were observed by electron microscopy on the newly isolated strain GRL 1172.
  • Seppa, Jeremias; Reischl, Bernhard; Sairanen, Hannu; Korpelainen, Virpi; Husu, Hannu; Heinonen, Martti; Raiteri, Paolo; Rohl, Andrew L.; Nordlund, Kai; Lassila, Antti (2017)
    Due to their operation principle atomic force microscopes (AFMs) are sensitive to all factors affecting the detected force between the probe and the sample. Relative humidity is an important and often neglected-both in experiments and simulations-factor in the interaction force between AFM probe and sample in air. This paper describes the humidity control system designed and built for the interferometrically traceable metrology AFM (IT-MAFM) at VTT MIKES. The humidity control is based on circulating the air of the AFM enclosure via dryer and humidifier paths with adjustable flow and mixing ratio of dry and humid air. The design humidity range of the system is 20-60 % rh. Force-distance adhesion studies at humidity levels between 25 % rh and 53 % rh are presented and compared to an atomistic molecular dynamics (MD) simulation. The uncertainty level of the thermal noise method implementation used for force constant calibration of the AFM cantilevers is 10 %, being the dominant component of the interaction force measurement uncertainty. Comparing the simulation and the experiment, the primary uncertainties are related to the nominally 7 nm radius and shape of measurement probe apex, possible wear and contamination, and the atomistic simulation technique details. The interaction forces are of the same order of magnitude in simulation and measurement (5 nN). An elongation of a few nanometres of the water meniscus between probe tip and sample, before its rupture, is seen in simulation upon retraction of the tip in higher humidity. This behaviour is also supported by the presented experimental measurement data but the data is insufficient to conclusively verify the quantitative meniscus elongation.
  • Rasinkangas, Pia; Tytgat, Hanne L. P.; Ritari, Jarmo; Reunanen, Justus; Salminen, Seppo; Palva, Airi; Douillard, Francois P.; de Vos, Willem M. (2020)
    Lacticaseibacillus rhamnosusGG is one of the best studied lactic acid bacteria in the context of probiotic effects.L. rhamnosusGG has been shown to prevent diarrhea in children and adults and has been implicated to have mitigating or preventive effects in several disorders connected to microbiota dysbiosis. The probiotic effects are largely attributed to its adhesive heterotrimeric sortase-dependent pili, encoded by thespaCBA-srtC1gene cluster. Indeed, the strain-specific SpaCBA pili have been shown to contribute to adherence, biofilm formation and host signaling. In this work we set out to generate non-GMO derivatives ofL. rhamnosusGG that adhere stronger to mucus compared to the wild-type strain using chemical mutagenesis. We selected 13 derivatives that showed an increased mucus-adherent phenotype. Deep shotgun resequencing of the strains enabled division of the strains into three classes, two of which revealed SNPs (single nucleotide polymorphisms) in thespaAandspaCgenes encoding the shaft and tip adhesive pilins, respectively. Strikingly, the other class derivatives demonstrated less clear genotype - phenotype relationships, illustrating that pili biogenesis and structure is also affected by other processes. Further characterization of the different classes of derivatives was performed by PacBio SMRT sequencing and RNAseq analysis, which resulted in the identification of molecular candidates driving pilin biosynthesis and functionality. In conclusion, we report on the generation and characterization of three classes of strongly adherentL. rhamnosusGG derivatives that show an increase in adhesion to mucus. These are of special interest as they provide a window on processes and genes driving piliation and its control inL. rhamnosusGG and offer a variety of non-GMO derivatives of this key probiotic strain that are applicable in food products.
  • Suutarinen, Maiju (Helsingin yliopisto, 2019)
    Imbalance of intestinal microbiota is called dysbiosis. Signs of dysbiosis are altered abundance of different bacterial species and reduced diversity together with altered interactions between bacterial species and microbiota and the host. Dysbiosis of intestinal microbiota is connected to many intestinal diseases and today many studies are focused to find so called “next generation” probiotics to be used for the alleviation of dysbiosis instead of traditional antibiotic treatments. The study was made in the Human Microbiome Research Program, Faculty of Medicine, University of Helsinki. Aim of the study was to isolate spore-forming bacterial species for the treatment of intestinal inflammation and infections with bacterial therapy. For this purpose, feces from a healthy adult who had acted as a donor for fecal microbiota transplantation was used to isolate spore-forming commensal bacteria. The isolated bacteria were identified and their ability to adhere into intestinal epithelium and strengthen it was investigated. Also anti-inflammatory potential of these isolated bacterial strains was investigated. For isolating bacteria three different heat treatments and ethanol and methanol treatments were used as a pre-treatment step. Pre-treated samples were cultivated on YCFA-media and isolates were picked from plates at different growth points for further cultivation. Selected isolates were purified, their DNA was isolated and they were identified by partial 16S rRNA -gene sequencing. From these identified isolates four isolates were chosen for further investigation and their full length 16S rRNA -gene was sequenced. These isolates were studied also by using API and aerotolerance tests. Potential anti-inflammatory and adhesion properties of the isolates were investigated by attenuation, adhesion and TER-experiments. In the isolation, the effect of different pre-treatments on the recovery of isolates was clear and based on sequencing isolates that were spore-forming anaerobic bacteria were selected for further investigation. Three of the isolates were Clostridium butyricum and one Blautia wexlerae species. Anti- and pro-inflammatory properties of these isolates were very different depending on isolate and one of them was potentially anti-inflammatory. Isolates also adhered differentially and two of them possibly strengthened gut epithelial barrier so they are promising for further research and in the future investigation with these isolates continues. Experience and results with different cultivation methods can be used to for further development of cultivation for anaerobic intestinal bacteria.
  • Mishra, Arjun K.; Megta, Abhin Kumar; Palva, Airi; von Ossowski, Ingemar; Krishnan, Vengadesan (2017)
    SpaE is the predicted basal pilin subunit in the sortase-dependent SpaFED pilus from the gut-adapted and commensal Lactobacillus rhamnosus GG. Thus far, structural characterization of the cell-wall-anchoring basal pilins has remained difficult and has been limited to only a few examples from pathogenic genera and species. To gain a further structural understanding of the molecular mechanisms that are involved in the anchoring and assembly of sortase-dependent pili in less harmful bacteria, L. rhamnosus GG SpaE for crystallization was produced by recombinant expression in Escherichia coli. Although several attempts to crystallize the SpaE protein were unsuccessful, trigonal crystals that diffracted to a resolution of 3.1 angstrom were eventually produced using PEG 3350 as a precipitant and high protein concentrations. Further optimization with a combination of additives led to the generation of SpaE crystals in an orthorhombic form that diffracted to a higher resolution of 1.5 angstrom. To expedite structure determination by SAD phasing, selenium-substituted (orthorhombic) SpaE crystals were grown and X-ray diffraction data were collected to 1.8 angstrom resolution.
  • Savijoki, Kirsi; Nyman, Tuula A.; Kainulainen, Veera; Miettinen, Ilkka; Siljamäki, Pia; Fallarero, Adyary; Sandholm, Jouko; Satokari, Reetta; Varmanen, Pekka (2019)
    Bacterial biofilms have clear implications in disease and in food applications involving probiotics. Here, we show that switching the carbohydrate source from glucose to fructose increased the biofilm formation and the total surface-antigenicity of a well-known probiotic, Lactobacillus rhamnosus GG. Surfaceomes (all cell surface-associated proteins) of GG cells grown with glucose and fructose in planktonic and biofilm cultures were identified and compared, which indicated carbohydrate source-dependent variations, especially during biofilm growth. The most distinctive differences under these conditions were detected with several surface adhesins (e.g., MBF, SpaC pilus protein and penicillin-binding proteins), enzymes (glycoside hydrolases, PrsA, PrtP, PrtR, and HtrA) and moonlighting proteins (glycolytic, transcription/translation and stress-associated proteins, r-proteins, tRNA synthetases, Clp family proteins, PepC, PepN, and PepA). The abundance of several known adhesins and candidate moonlighters, including enzymes acting on casein-derived peptides (ClpP, PepC, and PepN), increased in the biofilm cells grown on fructose, from which the surface-associated aminopeptidase activity mediated by PepC and PepN was further confirmed by an enzymatic assay. The mucus binding factor (MBF) was found most abundant in fructose grown biofilm cells whereas SpaC adhesin was identified specifically from planktonic cells growing on fructose. An additional indirect ELISA indicated both growth mode- and carbohydrate-dependent differences in abundance of SpaC, whereas the overall adherence of GG assessed with porcine mucus indicated that the carbon source and the growth mode affected mucus adhesion. The adherence of GG cells to mucus was almost completely inhibited by anti-SpaC antibodies regardless of growth mode and/or carbohydrate source, indicating the key role of the SpaCBA pilus in adherence under the tested conditions. Altogether, our results suggest that carbon source and growth mode coordinate mechanisms shaping the proteinaceous composition of GG cell surface, which potentially contributes to resistance, nutrient acquisition and cell-cell interactions under different conditions. In conclusion, the present study shows that different growth regimes and conditions can have a profound impact on the adherent and antigenic features of GG, thereby providing new information on how to gain additional benefits from this probiotic.
  • Tian, Li; Nyman, Henrietta; Kilgannon, Patrick; Yoshihara, Yoshihiro; Mori, Kensaku; Andersson, Leif C.; Kaukinen, Sami; Rauvala, Heikki; Gallatin, W. Michael; Gahmberg, Carl G. (Rockefeller University Press, 2000)
    Intercellular adhesion molecule-5 (ICAM-5) is a dendritically polarized membrane glycoprotein in telencephalic neurons, which shows heterophilic binding to leukocyte b2-integrins. Here, we show that the human ICAM-5 protein interacts in a homophilic manner through the binding of the immunoglobulin domain 1 to domains 4–5. Surface coated ICAM-5-Fc promoted dendritic outgrowth and arborization of ICAM- 5–expressing hippocampal neurons. During dendritogenesis in developing rat brain, ICAM-5 was in monomer form, whereas in mature neurons it migrated as a high molecular weight complex. The findings indicate that its homophilic binding activity was regulated by nonmonomer/monomer transition. Thus, ICAM-5 displays two types of adhesion activity, homophilic binding between neurons and heterophilic binding between neurons and leukocytes.
  • Wikman, Helena (Helsingfors universitet, 2010)
    Surface (S-) layers, structural entities that surround the cell envelope of various bacteria, are comprised of a porous lattice of identical protein or glycoprotein subunits. Interestingly, the S-layer is able to promote adherence to host epithelial cells in a variety of Lactobacillus species. L. amylovorus DSM 16698, a strain of porcine origin, encodes at least three putative types of S-layer proteins in its genome sequence. In this study the surface structure of L. amylovorus DSM 16698 strain and the adhesion properties of its S-layer proteins to porcine intestinal epithelial IPEC-1 cell line were examined based on preliminary results. In addition, host receptors potentially specific for S-layer proteins were isolated from IPEC-1 cells. Cloned recombinant S-layer proteins rSlpA and rSlpB of DSM 16698 were reassembled onto fluorescent-labeled L. amylovorus cell wall extracts as a means to mimic the native S-layer lattice structure. Adhesion between the reassembled recombinant S-layer complexes and IPEC-1 cells was assessed qualitatively by microscopy and quantitatively by measuring fluorescence intensity. Results from in vitro adhesion assays indicate that the rSlpA and rSlpB proteins both mediated the adherence of the L. amylovorus DSM 16698 strain to porcine intestinal epithelial cells. Antibodymediated adhesion inhibition experiments were also performed, in which the two rSlps were pretreated with their specific anti-rSlp serum, and showed that adhesion between the rSlps and IPEC-1 cells could be inhibited by the antibody treatment. Moreover, by using fluorescent-labeled rSlp-specific antibody, the surface structure of L. amylovorus cells was microscopically examined. With this immunofluorescent technique, the SlpA and SlpB proteins were both observed to localize on the cell surface and exhibit a similar distribution pattern. Putative S-layer host cell receptors were isolated from the interaction between the reassembled rSlp/cell wall complexes and IPEC-1 derived membrane proteins using a SDS-PAGE-based system. Receptor isolation experiments resulted in repeatedly the same protein profile. It has previously been shown that L. amylovorus DSM 16698 attaches to IPEC-1 cells, but the identities of surface-localized components that mediate this microbe-host interaction had yet to be determined. In this present study, S-layer proteins were found to be an important mediator in the interaction between L. amylovorus DSM 16698 and a porcine epithelial cell line. Additionally, it was shown how S-layer proteins are localized on the surface of L. amylovorus DSM 16698 cells.
  • Toivanen, Laura (Helsingfors universitet, 2009)
    Listeria monocytogenes is an important food-borne pathogen. It is a gram-positive bacterium, which multiplies in both aerobic and anaerobic conditions at a wide temperature area. It can grow in vacuum and modified atmosphere packages in refrigerated temperatures causing food hygienic risk. Listeria monocytogenes can cause life-threatening infection particularly in individuals who are immunocompromised, pregnant and elderly. The disease is divided into invasive and non-invasive form. The disease manifests typically with septicaemia, meningitis and gastroenteritis in non-invasive form. L. monocytogenes exists widely in the environment such as soil and water. It can find its way from the environment to the food processing plants and cause so called persistent contamination in the plant. The persistent contamination is a sum of many factors. Bacterial adhesion, acid and heat tolerance, the failure of disinfection, the adaptation of bacteria to sanitizing agents, complex processing machines and the existence of compartmentalization has its own role. Listeria monocytogenes strains can be divided into persistent and non-persistent strains. The persistent strains adhere to stainless steel surfaces faster than non-persistent strains. After the adhesion bacteria produce exopolysaccarides around themselves creating a biofilm. There are several methods to investigate biofilms. These methods can be divided into direct and indirect methods. In direct methods the biofilm is observed directly with microscope. The indirect methods are often colorimetric in other words the adherent bacteria are stained and the amount of colour is measured to estimate the amount of biofilm. The aim of the study was to set up a microtiter plate method to examine the adhesion of L. monocytogenes. At the same time the adhesion of persistent and non-persistent L. monocytogenes strains was compared. There were 20 L. monocytogenes strains that were isolated from food processing plants. The test was repeated 2 or 3 times. In the method which was used in this study the strain was incubated in the suspension in the microtiter plate. The adhered cells were stained and then the colour was dissolved. The optical density of the suspension was measured. The higher the optical density of the suspension was, the more there were adhered bacteria. Part of the studied strains had statistically significant difference in the adhesion. However most of the strains did not have a significant difference in adhesion. There was not statistically significant difference in the adhesion of persistent and non-persistent strains. The microtiter plate method proved to be a practical method to examine the biofilm of L. monocytogenes but its repeatability should still be improved. Differences in the adhesion of strains were observed with the method. Many strains can be examined at the same time with the method. The method is also easily modified to different research conditions.
  • Paetau, Sonja; Rolova, Taisia; Ning, Lin; Gahmberg, Carl G. (2017)
    The intercellular adhesion molecule-5 (ICAM-5) regulates neurite outgrowth and synaptic maturation. ICAM-5 overexpression in the hippocampal neurons induces filopodia formation in vitro. Since microglia are known to prune supernumerous synapses during development, we characterized the regulatory effect of ICAM-5 on microglia. ICAM-5 was released as a soluble protein from N-methyl-D-aspartic acid (NMDA)-treated neurons and bound by microglia. ICAM-5 promoted down-regulation of adhesion and phagocytosis in vitro. Microglia formed large cell clusters on ICAM-5-coated surfaces whereas they adhered and spread on the related molecule ICAM-1. ICAM-5 further reduced the secretion of the proinflammatory cytokines tumor necrosis factor a (TNF-alpha) and interleukin 1 beta (IL-1 beta), but on the contrary induced the secretion of the antiinflammatory IL-10 from lipopolysaccharide (LPS) stimulated microglia. Thus, ICAM-5 might be involved in the regulation of microglia in both health and disease, playing an important neuroprotective role when the brain is under immune challenges and as a "don't-eat-me" signal when it is solubilized from active synapses.
  • Hiippala, Kaisa; Khan, Imran; Ronkainen, Aki; Fredrik, Boulund; Vähä-Mäkilä, Helena; Suutarinen, Maiju Elina; Seifert, Maike; Engstrand, Lars; Satokari, Reetta (2022)
    Fecal microbiota transplantation (FMT) is an efficient treatment for recurrent Clostridioides difficile infection and currently investigated as a treatment for other intestinal and systemic diseases. Better understanding of the species potentially transferred in FMT is needed. We isolated from a healthy fecal donor a novel strain E10-96H of Pseudoruminococcus massiliensis, a recently described strictly anaerobic species currently represented only by the type strain. The whole genome sequence of E10-96H had over 98% similarity with the type strain. E10-96H carries 20 glycoside hydrolase encoding genes, degrades starch in vitro and thus may contribute to fiber degradation, cross-feeding of other species and butyrate production in the intestinal ecosystem. The strain carries pilus-like structures, harbors pilin genes in its genome and adheres to enterocytes in vitro but does not provoke a proinflammatory response. P. massiliensis seems to have commensal behavior with the host epithelium, and its role in intestinal ecology should be studied further.
  • Jahan, Farhana; Madhavan, Sudarrshan; Rolova, Taisia; Viazmina, Larisa; Grönholm, Mikaela; Gahmberg, Carl G. (2018)
    The integrin leukocyte function-associated antigen-1 (LFA-1) plays a pivotal role in leukocyte adhesion and migration, but the mechanism(s) by which this integrin is regulated has remained incompletely understood. LFA-1 integrin activity requires phosphorylation of its 2-chain and interactions of its cytoplasmic tail with various cellular proteins. The -chain is constitutively phosphorylated and necessary for cellular adhesion, but how the -chain regulates adhesion has remained enigmatic. We now show that substitution of the -chain phosphorylation site (S1140A) in T cells inhibits the phosphorylation of the functionally important Thr-758 in the 2-chain, binding of -actinin and 14-3-3 protein, and expression of an integrin-activating epitope after treatment with the stromal cell-derived factor-1. The presence of this substitution resulted in a loss of cell adhesion and directional cell migration. Moreover, LFA-1 activation through the T-cell receptor in cells expressing the S1140A LFA-1 variant resulted in less Thr-758 phosphorylation, -actinin and talin binding, and cell adhesion. The finding that the LFA-1 -chain regulates adhesion through the -chain via specific phosphorylation at Ser-1140 in the -chain has not been previously reported and emphasizes that both chains are involved in the regulation of LFA-1 integrin activity.
  • Tracz, Joanna; Handschuh, Luiza; Lalowski, Maciej; Marczak, Lukasz; Kostka-Jeziorny, Katarzyna; Perek, Bartlomiej; Wanic-Kossowska, Maria; Podkowinska, Alina; Tykarski, Andrzej; Formanowicz, Dorota; Luczak, Magdalena (2021)
    A progressive loss of functional nephrons defines chronic kidney disease (CKD). Complications related to cardiovascular disease (CVD) are the principal causes of mortality in CKD; however, the acceleration of CVD in CKD remains unresolved. Our study used a complementary proteomic approach to assess mild and advanced CKD patients with different atherosclerosis stages and two groups of patients with different classical CVD progression but without renal dysfunction. We utilized a label-free approach based on LC-MS/MS and functional bioinformatic analyses to profile CKD and CVD leukocyte proteins. We revealed dysregulation of proteins involved in different phases of leukocytes' diapedesis process that is very pronounced in CKD's advanced stage. We also showed an upregulation of apoptosis-related proteins in CKD as compared to CVD. The differential abundance of selected proteins was validated by multiple reaction monitoring, ELISA, Western blotting, and at the mRNA level by ddPCR. An increased rate of apoptosis was then functionally confirmed on the cellular level. Hence, we suggest that the disturbances in leukocyte extravasation proteins may alter cell integrity and trigger cell death, as demonstrated by flow cytometry and microscopy analyses. Our proteomics data set has been deposited to the ProteomeXchange Consortium via the PRIDE repository with the data set identifier PXD018596.
  • University, Aalto; Tersteegen, Jennifer; Sammaljarvi, Juuso; Aranko, A. Sesilja; Linder, Markus B. (2021)
    For developing novel fully biological materials, a central question is how we can utilize natural components in combination with biomimetic strategies in ways that both allow feasible processing and high performance. Within this development, adhesives play a central role. Here, we have combined two of nature's excellent materials, silk and cellulose, to function as an adhesive system. As an initial step in processing, wood was delignified. Without lignin, the essential microstructure and alignment of the wood remain, giving a strong scaffold that is versatile to process further. A recombinant spider silk protein was used as a fully biological and water-based adhesive. The adhesive strength was excellent with an average value of 6.7 MPa, with a maximum value of up to 10 MPa. Samples of different strengths showed characteristic features, with high tear-outs for weaker samples and only little tear-out for strong samples. As references, bovine serum albumin and starch were used. Based on the combined data, we propose an overall model for the system and highlight how multiple variables affect performance. Adhesives, in particular, biobased ones, must be developed to be compatible with the overall adherend system for suitable infiltration and so that their mechanical properties match the adherend. The engineering of proteins gives an unmatched potential for designing adhesive systems that additionally have desired properties such as being fully water-based, biologically produced, and renewable.
  • Tuohimaa, Eira (Helsingin yliopisto, 2019)
    Adhesion of the food into the packaging has an important role in various stages of the supply chain of food production to recycling. If the food sticks to the surface of the package and the package does not get completely empty, there will be ethical and ecological problems due to the use of resources such as water, raw materials and energy which are wasted in considerable quantities. If the packaging does not empty properly, but leaves residues, the image of product’s quality in the eyes of the consumer will be reduced. The aim of this study was to develop packaging materials that reduce food losses by improving the release of the food from its packaging. The research topics were the emptying properties of the packaging materials and the adhesion of the oily foods to their surfaces. The work was carried out by testing the coated paperboards and trays adhesion properties. As model products, commercial marinade and rapeseed oil were used, and their viscosities were determined. The method used were 80° tilt test, stickiness test, contact angle measurement and chemical extraction combined with gas chromatography. Based on the results of the study, the amount of residue from an oily food at the surface of the packaging can be influenced by appropriate combination of mechanical and chemical treatments. Using a PE coating which is glossy and non-patterned with a chemical treatment is the best for ensuring removal of oily foods removed from the packaging. Food waste can be reduced by choosing the proper packaging type for each foodstuff based on its attributes.
  • Onwunyi, Chuks (Helsingin yliopisto, 2015)
    Health benefits associated with the ingestion of certain lactobacilli known as probiotics have increased the research and incorporation of these bacteria into food products. Lactobacillus rhamnosus GG is a well-known and studied probiotic organism. Upon ingestion, probiotics survive acid and bile stress and then adhere to the epithelial cell walls to elicit health benefits. Adhesion promotes interaction between probiotic cells and epithelial cells which is necessary for probiotics to confer health benefits. Adhesion is also the first step in biofilm formation which aids adaptability and cell-cell interaction. The aim of this work was to investigate the effect of different carbohydrates on the biofilm formation and antigenicity of Lb. rhamnosus GG. Biofilm formation was performed using 96-well microtiter plating method under elevated carbon dioxide (5% CO2) conditions for 24, 48 and 72 hours in the presence of fourteen different carbohydrates. Certain carbohydrates were found to promote the biofilm formation. The expressed antigenic proteins at the cell surface of biofilms from these carbohydrates were also isolated and investigated using 1DE immunoblot analysis. Four carbohydrates were shown to markedly increase the biofilm of Lb. rhamnosus GG under the indicated conditions. For three of the tested carbohydrates the most efficient biofilm formation was obtained after 48 hours of cultivation, whereas for one of the carbohydrates longer time was required to achieve the same biofilm formation efficiency. One dimensional gel electrophoresis coupled with immunoblotting using antibodies raised against whole Lb. rhamnosus GG cells indicated that the increased biofilm formation is closely associated with the increased surface antigenicity. The obtained findings suggest that certain carbohydrates have a central role in stimulating biofilm mode of growth as well as improving the probiotic features of Lb. rhamnosus GG strain.