Impact of growth conditions and role of sigB on Listeria monocytogenes fitness in single and mixed biofilms cultured with Lactobacillus plantarum
Saa Ibusquiza, P. ; Nierop Groot, M.N. ; Deban Valles, A. ; Abee, T. ; Besten, H.M.W. den - \ 2015
Food Research International 71 (2015). - ISSN 0963-9969 - p. 140 - 145.
lactic-acid bacteria - oxidative stress resistance - gram-positive bacteria - superoxide-dismutase - tolerance response - arginine deiminase - species biofilms - stainless-steel - sodium-chloride - sigma(b)
The role of sigB, a major transcriptional regulator of stress response genes, was assessed in formation of single and mixed species biofilms of Listeria monocytogenes EGD-e and Lactobacillus plantarum WCFS1 as secondary species at 20 °C and 30 °C using different medium compositions (nutrient-rich medium with and without supplementary manganese, glucose and salt). L. monocytogenes showed significant biofilm development at both temperatures and in all media tested although less biofilm was formed when glucose was supplemented only. The contribution of L. monocytogenes to the mixed species biofilm declined especially at higher temperature in glucose-rich medium in the absence and presence of manganese, due to lactic acid formation with concomitant decrease in culture pH below the pHmin of L. monocytogenes. Using an in-frame sigB deletion mutant and a complementation mutant we showed that sigB contributed to survival under these acid stress conditions. Notably, the additional presence of salt protected L. monocytogenes in the acidic mixed species biofilms resulting in an increase of around 2–3 log10 cfu/ml and this phenomenon showed to be sigB-dependent.
Characterisation of biofilms formed by Lactobacillus plantarum WCFS1 and food spoilage isolates
Fernández Ramírez, M.D. ; Smid, E.J. ; Abee, T. ; Nierop Groot, M.N. - \ 2015
International Journal of Food Microbiology 207 (2015). - ISSN 0168-1605 - p. 23 - 29.
lactic-acid bacteria - enterococcal surface protein - listeria-monocytogenes - pseudomonas-putida - bacillus-subtilis - starter cultures - genetic-analysis - rhamnosus gg - resistance - industry
Lactobacillus plantarum has been associated with food spoilage in a wide range of products and the biofilm growth mode has been implicated as a possible source of contamination. In this study we analysed the biofilm forming capacity of L. plantarum WCFS1 and six food spoilage isolates. Biofilm formation as quantified by crystal violet staining and colony forming units was largely affected by the medium composition, growth temperature and maturation time and by strain specific features. All strains showed highest biofilm formation in Brain Heart Infusion medium supplemented with manganese and glucose. For L. plantarum biofilms the crystal violet (CV) assay, that is routinely used to quantify total biofilm formation, correlates poorly with the number of culturable cells in the biofilm. This can in part be explained by cell death and lysis resulting in CV stainable material, conceivably extracellular DNA (eDNA), contributing to the extracellular matrix. The strain to strain variation may in part be explained by differences in levels of eDNA, likely as result of differences in lysis behaviour. In line with this, biofilms of all strains tested, except for one spoilage isolate, were sensitive to DNase treatment. In addition, biofilms were highly sensitive to treatment with Proteinase K suggesting a role for proteins and/or proteinaceous material in surface colonisation. This study shows the impact of a range of environmental factors and enzyme treatments on biofilm formation capacity for selected L. plantarum isolates associated with food spoilage, and may provide clues for disinfection strategies in food industry.
The relationship between fermented food intake and mortality risk in the European Prospective Investigation into Cancer and Nutrition-Netherlands cohort
Praagman, J. ; Dalmeijer, G.W. ; Schouw, Y.T. van der; Soedamah-Muthu, S.S. ; Verschuren, W.M.M. ; Bueno-de Mesquita, H.B. ; Geleijnse, J.M. ; Beulens, J.W.J. - \ 2015
The British journal of nutrition 113 (2015). - ISSN 0007-1145 - p. 498 - 506.
coronary-heart-disease - lactic-acid bacteria - dairy-products - colorectal-cancer - consumption - stroke - metaanalysis - questionnaire - menaquinone - men
The objective of the present study was to investigate the relationship between total and subtypes of bacterial fermented food intake (dairy products, cheese, vegetables and meat) and mortality due to all causes, total cancer and CVD. From the European Prospective Investigation into Cancer and Nutrition-Netherlands cohort, 34 409 Dutch men and women, aged 20–70 years who were free from CVD or cancer at baseline, were included. Baseline intakes of total and subtypes of fermented foods were measured with a validated FFQ. Data on the incidence and causes of death were obtained from the national mortality register. Cox proportional hazards models were used to analyse mortality in relation to the quartiles of fermented food intake. After a mean follow-up of 15 (sd 2·5) years, 2436 deaths occurred (1216 from cancer and 727 from CVD). After adjustment for age, sex, total energy intake, physical activity, education level, hypertension, smoking habit, BMI, and intakes of fruit, vegetables and alcohol, total fermented food intake was not found to be associated with mortality due to all causes (hazard ratio upper v. lowest quartile (HRQ4 v. Q1) 1·00, 95 % CI 0·88, 1·13), cancer (HRQ4 v. Q1 1·02, 95 % CI 0·86, 1·21) or CVD (HRQ4 v. Q1 1·04, 95 % CI 0·83, 1·30). Bacterial fermented foods mainly consisted of fermented dairy foods (78 %) and cheese (16 %). None of the subtypes of fermented foods was consistently related to mortality, except for cheese which was moderately inversely associated with CVD mortality, and particularly stroke mortality (HRQ4 v. Q1 0·59, 95 % CI 0·38, 0·92, Ptrend= 0·046). In conclusion, the present study provides no strong evidence that intake of fermented foods, particularly fermented dairy foods, is associated with mortality.
Effect of sublethal preculturing on the survival of probiotics and metabolite formation in set-yoghurt
Settachaimongkon, S. ; Valenberg, H.J.F. van; Winata, V. ; Wang, X. ; Nout, M.J.R. ; Hooijdonk, A.C.M. van; Zwietering, M.H. ; Smid, E.J. - \ 2015
Food Microbiology 49 (2015). - ISSN 0740-0020 - p. 104 - 115.
lactic-acid bacteria - fermented milks - tolerance response - functional foods - stress responses - bifidobacteria - lactobacillus - cultures - strains - microorganisms
The objective of this study was to investigate the effect of preculturing of Lactobacillus rhamnosus GG and Bifidobacterium animalis subsp. lactis BB12 under sublethal stress conditions on their survival and metabolite formation in set-yoghurt. Prior to co-cultivation with yoghurt starters in milk, the two probiotic strains were precultured under sublethal stress conditions (combinations of elevated NaCl and low pH) in a batch fermentor. The activity of sublethally precultured probiotics was evaluated during fermentation and refrigerated storage by monitoring bacterial population dynamics, milk acidification and changes in volatile and non-volatile metabolite profiles of set-yoghurt. The results demonstrated adaptive stress responses of the two probiotic strains resulting in their viability improvement without adverse influence on milk acidification. A complementary metabolomic approach using SPME-GC/MS and 1H-NMR resulted in the identification of 35 volatiles and 43 non-volatile polar metabolites, respectively. Principal component analysis revealed substantial impact of the activity of sublethally precultured probiotics on metabolite formation demonstrated by distinctive volatile and non-volatile metabolite profiles of set-yoghurt. Changes in relative abundance of various aroma compounds suggest that incorporation of stress-adapted probiotics considerably influences the organoleptic quality of product. This study provides new information on the application of stress-adapted probiotics in an actual food-carrier environment
Construction and validation of a mCherry protein vector for promoter analysis in Lactobacillus acidophilus
Mohedano, M.L. ; Garcia-Cayuela, T. ; Perez-Ramos, A. ; Gaiser, R.A. ; Requena, T. ; Lopez, P. - \ 2015
Journal of Industrial Microbiology and Biotechnology 42 (2015)2. - ISSN 1367-5435 - p. 247 - 253.
lactic-acid bacteria - controlled gene-expression - streptococcus-pneumoniae - lactococcus-lactis - plasmid - cloning
Lactobacilli are widespread in natural environments and are increasingly being investigated as potential health modulators. In this study, we have adapted the broad-host-range vector pNZ8048 to express the mCherry protein (pRCR) to expand the usage of the mCherry protein for analysis of gene expression in Lactobacillus. This vector is also able to replicate in Streptococcus pneumoniae and Escherichia coli. The usage of pRCR as a promoter probe was validated in Lactobacillus acidophilus by characterizing the regulation of lactacin B expression. The results show that the regulation is exerted at the transcriptional level, with lbaB gene expression being specifically induced by co-culture of the L. acidophilus bacteriocin producer and the S. thermophilus STY-31 inducer bacterium.
Spoilage evaluation, shelf-life prediction, and potential spoilage organisms of tropical brackish water shrimp (Penaeus notialis) at different storage temperatures
Dabade, D.S. ; Besten, H.M.W. den; Azokpota, P. ; Nout, M.J.R. ; Hounhouigan, D.J. ; Zwietering, M.H. - \ 2015
Food Microbiology 48 (2015). - ISSN 0740-0020 - p. 8 - 16.
lactic-acid bacteria - cold-smoked salmon - modified atmosphere - parapenaeus-longirostris - pandalus-borealis - chilled storage - chemical characteristics - indole production - hydrogen-sulfide - microbial-flora
Maintaining the freshness of shrimp is a concern to shrimp stakeholders. To improve shrimp quality management, it is of importance to evaluate shrimp spoilage characteristics. Therefore, microbiological, sensory, and chemical changes of naturally contaminated tropical brackish water shrimp (Penaeus notialis) during storage at 28 °C, 7 °C and 0 °C were assessed. H2S-producing bacteria were the dominant group of microorganisms at 28 °C and 7 °C whereas Pseudomonas spp. were dominant at 0 °C. Total volatile basic nitrogen and trimethylamine correlated well (R2 > 0.90) with the sensory scores. An empirical model to predict the shelf-life of naturally contaminated tropical shrimp as a function of storage temperature was developed. Specific groups of organisms were isolated at the sensory rejection times and assessed for spoilage potential in shrimps of which the endogenous flora was heat inactivated. Isolates capable of producing strong off-odor identified by 16S rRNA sequencing were mainly lactic acid bacteria (LAB) and Enterobacteriaceae at 28 °C or 7 °C and Pseudomonas spp. and LAB at 0 °C. The study contributes to the knowledge about tropical shrimp spoilage and provides a basis for the development of methods and tools to improve shrimp quality management. Keywords: Shrimp quality; Microbiological change; TVBN; Sensory rejection; Shelf-life prediction
Interactions between formulation and spray drying conditions related to survival of Lactobacillus plantarum WCFS1
Perdana, J.A. ; Fox, M.B. ; Siwei, C. ; Boom, R.M. ; Schutyser, M.A.I. - \ 2014
Food Research International 56 (2014). - ISSN 0963-9969 - p. 9 - 17.
glass-transition temperature - membrane phase-behavior - lactic-acid bacteria - flow-cytometry - industrial applications - dairy ingredients - osmotic-stress - water activity - rhamnosus gg - gel phase
Protective solid carriers are commonly added to probiotic cultures prior to drying. Their formulation is not trivial and depends on the drying conditions applied. In this study, we systematically investigated the influence of formulation parameters on the survival of Lactobacillus plantarum WCFS1 after drying. Low molecular weight carbohydrates (less than 2 kDa) with high glass transition temperatures provided the highest level of protection at both low (25 degrees C) and high (50 degrees C or higher) drying temperatures. Low molecular weight carbohydrates may provide stabilization by closely interacting with the lipid bilayer of the cell membranes. Meanwhile, carbohydrates with high glass transition temperatures probably provide stabilization via fixation of the cells in a glassy powder. Furthermore, adequate amounts of solid carrier are required to sufficiently stabilize the cells during drying. During drying, crystallization of solid carriers may occur. Depending on the crystal geometry, crystallization can be either beneficial (e.g. with mannitol or sorbitol) or detrimental (e.g. with lactose) to cell survival. Finally, the effect of formulation on cell viability during storage was studied. A decimal reduction time of approximately 300 days was observed when spray dried L. plantarum WCFS1 was stored at temperatures below 40 degrees C. The outcome of this study was used as a basis to construct a generalized diagram to indicate the combinations of formulation and drying conditions to maximally retain viability and operate dryers at high efficiency. (C) 2013 Elsevier Ltd. All rights reserved.
H2O2 Production in Species of the Lactobacillus acidophilus Group: a Central Role for a Novel NADH-Dependent Flavin Reductase
Hertzberger, R. ; Arents, J. ; Dekker, H.L. ; Pridmore, R.D. ; Gysler, C. ; Kleerebezem, M. ; Mattos, M.J.T. de - \ 2014
Applied and Environmental Microbiology 80 (2014)7. - ISSN 0099-2240 - p. 2229 - 2239.
hydrogen-peroxide production - alkyl hydroperoxide reductase - activated-receptor-gamma - lactic-acid bacteria - escherichia-coli - streptococcus-pneumoniae - amphibacillus-xylanus - pseudomonas-putida - johnsonii ncc-533 - crystal-structure
Hydrogen peroxide production is a well-known trait of many bacterial species associated with the human body. In the presence of oxygen, the probiotic lactic acid bacterium Lactobacillus johnsonii NCC 533 excretes up to 1 mM H2O2, inducing growth stagnation and cell death. Disruption of genes commonly assumed to be involved in H2O2 production (e.g., pyruvate oxidase, NADH oxidase, and lactate oxidase) did not affect this. Here we describe the purification of a novel NADH-dependent flavin reductase encoded by two highly similar genes (LJ_0548 and LJ_0549) that are conserved in lactobacilli belonging to the Lactobacillus acidophilus group. The genes are predicted to encode two 20-kDa proteins containing flavin mononucleotide (FMN) reductase conserved domains. Reductase activity requires FMN, flavin adenine dinucleotide (FAD), or riboflavin and is specific for NADH and not NADPH. The K-m for FMN is 30 +/- 8 mu M, in accordance with its proposed in vivo role in H2O2 production. Deletion of the encoding genes in L. johnsonii led to a 40-fold reduction of hydrogen peroxide formation. H2O2 production in this mutant could only be restored by in trans complementation of both genes. Our work identifies a novel, conserved NADH-dependent flavin reductase that is prominently involved in H2O2 production in L. johnsonii.
Development of the recombinase-based in vivo expression technology in Streptococcus thermophilus and validation using the lactose operon promoter
Junjua, M. ; Galia, W. ; Gaci, N. ; Uriot, O. ; Genay, M. ; Bachmann, H. ; Kleerebezem, M. ; Dary, A. ; Roussel, Y. - \ 2014
Journal of Applied Microbiology 116 (2014)3. - ISSN 1364-5072 - p. 620 - 631.
lactic-acid bacteria - gene-expression - lactococcus-lactis - human gut - yogurt - system - mice - identification - transformation - proteinase
To construct and validate the recombinase-based in vivo expression technology (R-IVET) tool in Streptococcus thermophilus (ST).
Methods and Results
The R-IVET system we constructed in the LMD-9 strain includes the plasmid pULNcreB allowing transcriptional fusion with the gene of the site-specific recombinase Cre and the chromosomal cassette containing a spectinomycin resistance gene flanked by two loxP sites. When tested in M17 medium, promoters of the genes encoding the protease PrtS, the heat-shock protein Hsp16 and of the lactose operon triggered deletion of the cassette, indicating promoter activity in these conditions. The lactose operon promoter was also found to be activated during the transit in the murine gastrointestinal tract.
The R-IVET system developed in ST is relatively stable, functional, very sensitive and can be used to assay activity of promoters, which are specifically active in in vivo conditions.
Significance and Impact of the Study
This first adaptation of R-IVET to ST provides a highly valuable tool allowing an exploration of the physiological state of ST in the GIT of mammals, fermentation processes or dairy products.
Functional characterization of probiotic surface layer protein-carrying Lactobacillus amylovorus strains
Hynönen, U. ; Kant, R. ; Lähteinen, T. ; Pietilä, T.E. ; Beganovic, J. ; Smidt, H. ; Uroic, K. ; Åvall-Jääskeläinen, S. ; Palva, A. - \ 2014
BMC Microbiology 14 (2014). - ISSN 1471-2180 - 16 p.
enterotoxigenic escherichia-coli - human intestinal mucus - lactic-acid bacteria - human dendritic cells - s-layer - in-vitro - acidophilus ncfm - aeromonas-salmonicida - epithelial-cells - immune-system
Background - Adhesiveness to intestinal epithelium, beneficial immunomodulating effects and the production of pathogen-inhibitory compounds are generally considered as beneficial characteristics of probiotic organisms. We showed the potential health-promoting properties and the mechanisms of probiotic action of seven swine intestinal Lactobacillus amylovorus isolates plus the type strain (DSM 20531T) by investigating their adherence to porcine intestinal epithelial cells (IPEC-1) and mucus as well as the capacities of the strains to i) inhibit the adherence of Escherichia coli to IPEC-1 cells, ii) to produce soluble inhibitors against intestinal pathogens and iii) to induce immune signaling in dendritic cells (DCs). Moreover, the role of the L. amylovorus surface (S) –layers - symmetric, porous arrays of identical protein subunits present as the outermost layer of the cell envelope - in adherence to IPEC-1 cells was assessed using a novel approach which utilized purified cell wall fragments of the strains as carriers for the recombinantly produced S-layer proteins. Results - Three of the L. amylovorus strains studied adhered to IPEC-1 cells, while four strains inhibited the adherence of E. coli, indicating additional mechanisms other than competition for binding sites being involved in the inhibition. None of the strains bound to porcine mucus. The culture supernatants of all of the strains exerted inhibitory effects on the growth of E. coli, Salmonella, Listeria and Yersinia, and a variable, strain-dependent induction was observed of both pro- and anti-inflammatory cytokines in human DCs. L. amylovorus DSM 16698 was shown to carry two S-layer-like proteins on its surface in addition to the major S-layer protein SlpA. In contrast to expectations, none of the major S-layer proteins of the IPEC-1 -adhering strains mediated bacterial adherence. Conclusions - We demonstrated adhesive and significant pathogen inhibitory efficacies among the swine intestinal L. amylovorus strains studied, pointing to their potential use as probiotic feed supplements, but no independent role could be demonstrated for the major S-layer proteins in adherence to epithelial cells. The results indicate that many intestinal bacteria may coexist with and confer benefits to the host by mechanisms not attributable to adhesion to epithelial cells or mucus.
Functional implications of the microbial community structure of undefined mesophilic starter cultures
Smid, E.J. ; Erkus, O. ; Spus, M. ; Wolkers-Rooijackers, J.C.M. ; Alexeeva, S.V. ; Kleerebezem, M. - \ 2014
Microbial Cell Factories 13 (2014)suppl. 1. - ISSN 1475-2859
lactic-acid bacteria - lactococcus-lactis - subsp lactis - listeria-monocytogenes - biovar diacetylactis - metabolic models - cheddar cheese - diversity - cremoris - dairy
This review describes the recent advances made in the studies of the microbial community of complex and undefined cheese starter cultures. We report on work related to the composition of the cultures at the level of genetic lineages, on the presence and activity of bacteriophages and on the population dynamics during cheese making and during starter culture propagation. Furthermore, the link between starter composition and starter functionality will be discussed. Finally, recent advances in predictive metabolic modelling of the multi-strain cultures will be discussed in the context of microbe-microbe interactions.
GtfA and GtfB are both required for protein O-glycosylation in Lactobacillus plantarum
Lee, I.C. ; Swam, I.I. van; Tomita, S. ; Morsomme, P. ; Rolain, T. ; Hols, P. ; Kleerebezem, M. ; Bron, P.A. - \ 2014
Journal of Bacteriology 196 (2014)9. - ISSN 0021-9193 - p. 1671 - 1682.
complete genome sequence - lactic-acid bacteria - escherichia-coli - campylobacter-jejuni - acidophilus ncfm - epithelial-cells - surface protein - rhamnosus gg - glycoproteins - binding
Acm2, the major autolysin of Lactobacillus plantarum WCFS1, was recently found to be O-glycosylated with N-acetylhexosamine, likely N-acetylglucosamine (GlcNAc). In this study, we set out to identify the glycosylation machinery by employing a comparative genomics approach to identify Gtf1 homologues, which are involved in fimbria-associated protein 1 (Fap1) glycosylation in Streptococcus parasanguinis. This in silico approach resulted in the identification of 6 candidate L. plantarum WCFS1 genes with significant homology to Gtf1, namely, tagE1 to tagE6. These candidate genes were targeted by systematic gene deletion, followed by assessment of the consequences on glycosylation of Acm2. We observed a changed mobility of Acm2 on SDS-PAGE in the tagE5E6 deletion strain, while deletion of other tagE genes resulted in Acm2 mobility comparable to that of the wild type. Subsequent mass spectrometry analysis of excised and in-gel-digested Acm2 confirmed the loss of glycosylation on Acm2 in the tagE5E6 deletion mutant, whereas a lectin blot using GlcNAc-specific succinylated wheat germ agglutinin (sWGA) revealed that besides Acm2, tagE5E6 deletion also abolished all but one other sWGA-reactive, protease-sensitive signal. Only complementation of both tagE5 and tagE6 restored those sWGA lectin signals, establishing that TagE5 and TagE6 are both required for the glycosylation of Acm2 as well as the vast majority of other sWGA-reactive proteins. Finally, sWGA lectin blotting experiments using a panel of 8 other L. plantarum strains revealed that protein glycosylation is a common feature in L. plantarum strains. With the establishment of these enzymes as protein glycosyltransferases, we propose to rename TagE5 and TagE6 as GtfA and GtfB, respectively.
Functional Identification of Conserved Residues Involved in Lactobacillus rhamnosus Strain GG Sortase Specificity and Pilus Biogenesis
Douillard, F.P. ; Rasinkangas, P. ; Ossowski, I. von; Reunanen, J. ; Palva, A. ; Vos, W.M. de - \ 2014
Journal of Biological Chemistry 289 (2014)22. - ISSN 0021-9258 - p. 15764 - 15775.
complete genome sequence - gram-positive bacteria - enterococcus-faecium isolate - group-b streptococcus - lactic-acid bacteria - lactococcus-lactis - corynebacterium-diphtheriae - bacillus-anthracis - pilin subunit - reveals pili
In Gram-positive bacteria, sortase-dependent pili mediate the adhesion of bacteria to host epithelial cells and play a pivotal role in colonization, host signaling, and biofilm formation. Lactobacillus rhamnosus strain GG, a well known probiotic bacterium, also displays on its cell surface mucus-binding pilus structures, along with other LPXTG surface proteins, which are processed by sortases upon specific recognition of a highly conserved LPXTG motif. Bioinformatic analysis of all predicted LPXTG proteins encoded by the L. rhamnosus GG genome revealed a remarkable conservation of glycine residues juxtaposed to the canonical LPXTG motif. Here, we investigated and defined the role of this so-called triple glycine (TG) motif in determining sortase specificity during the pilus assembly and anchoring. Mutagenesis of the TG motif resulted in a lack or an alteration of the L. rhamnosus GG pilus structures, indicating that the TG motif is critical in pilus assembly and that they govern the pilin-specific and housekeeping sortase specificity. This allowed us to propose a regulatory model of the L. rhamnosus GG pilus biogenesis. Remarkably, the TG motif was identified in multiple pilus gene clusters of other Gram-positive bacteria, suggesting that similar signaling mechanisms occur in other, mainly pathogenic, species.
The impact of selected strains of probiotic bacteria on metabolite formation in set yoghurt
Settachaimongkon, S. ; Nout, M.J.R. ; Antunes Fernandes, E.C. ; Hooijdonk, A.C.M. van; Zwietering, M.H. ; Smid, E.J. ; Valenberg, H.J.F. van - \ 2014
International Dairy Journal 38 (2014)1. - ISSN 0958-6946 - p. 1 - 10.
nuclear-magnetic-resonance - delbrueckii subsp bulgaricus - lactic-acid bacteria - streptococcus-thermophilus - fermented milks - lactobacillus-acidophilus - functional foods - starter cultures - flavor compounds - dairy-products
The influence of Lactobacillus rhamnosus GG and Bifidobacterium animalis subsp. lactis BB12 in cofermentation with traditional starters on metabolite formation in set yoghurt was evaluated. Microbial activity during fermentation and refrigerated storage was investigated by monitoring bacterial population dynamics, milk acidification and overall changes in yoghurt metabolite profiles. A complementary metabolomics approach using solid-phase microextraction-gas chromatography/mass spectrometry and 1H nuclear magnetic resonance resulted in the identification of 37 volatile and 43 non-volatile metabolites, respectively. Results demonstrated that the two probiotic strains did not influence acidity and the key-aroma volatile metabolites of set yoghurt. However, a contribution by the presence of L. rhamnosus GG on the non-volatile metabolite profile of yoghurt was specifically noticed during storage. Multivariate analysis allowed yoghurts fermented by different starter combinations and different durations of storage to be differentiated according to their metabolite profiles. This provides new insights regarding the impact of probiotics on the metabolome of yoghurt.
Influence of different proteolytic strains of Streptococcus thermophilus in co-culture with Lactobacillus delbrueckii subsp. bulgaricus on the metabolite profile of set-yoghurt
Settachaimongkon, S. ; Nout, M.J.R. ; Antunes Fernandes, E.C. ; Hettinga, K.A. ; Vervoort, J.J.M. ; Hooijdonk, A.C.M. van; Zwietering, M.H. ; Smid, E.J. ; Valenberg, H.J.F. van - \ 2014
International Journal of Food Microbiology 177 (2014). - ISSN 0168-1605 - p. 29 - 36.
lactic-acid bacteria - nuclear-magnetic-resonance - food fermentations - volatile compounds - functional foods - flavor formation - fermented milks - dairy-cows - shelf-life - metabolomics
Proto-cooperation between Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus is one of the key factors that determine the fermentation process and final quality of yoghurt. In this study, the interaction between different proteolytic strains of S. thermophilus and L. delbrueckii subsp. bulgaricuswas investigated in terms of microbial growth, acidification and changes in the biochemical composition of milk during set-yoghurt fermentation. A complementary metabolomics approach was applied for global characterization of volatile and non-volatile polar metabolite profiles of yoghurt associated with proteolytic activity of the individual strains in the starter cultures. The results demonstrated that only non-proteolytic S. thermophilus (Prt-) strain performed proto-cooperation with L. delbrueckii subsp. bulgaricus. The proto-cooperation resulted in significant higher populations of the two species, faster milk acidification, significant abundance of aroma volatiles and non-volatile metabolites desirable for a good organoleptic quality of yoghurt. Headspace SPME-GC/MS and 1H NMR resulted in the identification of 35 volatiles and 43 non-volatile polar metabolites, respectively. Furthermore, multivariate statistical analysis allows discriminating set-yoghurts fermented by different types of starter cultures according to their metabolite profiles. Our finding underlines that selection of suitable strain combinations in yoghurt starters is important for achieving the best technological performance regarding the quality of product.
Stability of (Bio)Functionalized Porous Aluminum Oxide
Debrassi, A. ; Ribbera, A. ; Vos, W.M. de; Wennekes, T. ; Zuilhof, H. - \ 2014
Langmuir 30 (2014). - ISSN 0743-7463 - p. 1311 - 1320.
self-assembled monolayers - lactic-acid bacteria - lactobacillus-plantarum - nanoporous alumina - click chemistry - anodic alumina - surfaces - adsorption - membrane - carbohydrate
Porous aluminum oxide (PAO), a nanostructured support for, among others, culturing microorganisms, was chemically modified in order to attach biomolecules that can selectively interact with target bacteria. We present the first comprehensive study of monolayer-modified PAO using conditions that are relevant to microbial growth with a range of functional groups (carboxylic acid, a-hydroxycarboxylic acid, alkyne, alkene, phosphonic acid, and silane). Their stability was initially assessed in phosphate-buffered saline (pH 7.0) at room temperature. The most stable combination (PAO with phosphonic acids) was further studied over a range of physiological pHs (4–8) and temperatures (up to 80 °C). Varying the pH had no significant effect on the stability, but it gradually decreased with increasing temperature. The stability of phosphonic acid-modified PAO surfaces was shown to depend strongly on the other terminal group of the monolayer structure: in general, hydrophilic monolayers were less stable than hydrophobic monolayers. Finally, an alkyne-terminated PAO surface was reacted with an azide-linked mannose derivative. The resulting mannose-presenting PAO surface showed the clearly increased adherence of a mannose-binding bacterium, Lactobacillus plantarum, and also allowed for bacterial outgrowth.
The effect of dietary hydroxyproline and dietary oxalate on urinary oxalate excretion in cats
Dijcker, J.C. ; Plantinga, E.A. ; Thomas, D.G. ; Queau, Y. ; Biourge, V.C. ; Hendriks, W.H. - \ 2014
Journal of Animal Science 92 (2014). - ISSN 0021-8812 - p. 577 - 584.
lactic-acid bacteria - oxalobacter-formigenes - primary hyperoxaluria - feline uroliths - adult cats - calcium - rats - dogs - metabolism - canine
In humans and rodents, dietary hydroxyproline (hyp) and oxalate intake affect urinary oxalate (Uox) excretion. Whether Uox excretion occurs in cats was tested by feeding diets containing low oxalate (13 mg/100g DM) with high (Hhyp-Lox), moderate (Mhyp-Lox), and low hyp (Lhyp-Lox) concentrations (3.8, 2.0 and 0.2 g/100g DM, respectively), and low hyp with high oxalate (93 mg/100g DM; Lhyp-Hox) to 8 adult, female cats in a 48-d study using a Latin square design. Cats were randomly allocated to 1 of the four 12-d treatment periods and fed according to individual energy needs. Feces and urine were collected quantitatively using modified litter boxes during the final 5 d of each period. Feces were analyzed for oxalate and Ca, and urine for specific density, pH, oxalate, Ca, P, Mg, Na, K, ammonia, citrate, urate, sulphate, and creatinine. Increasing hyp intake (0.2, 2.0, and 3.8 g/100g DM) resulted in increased Uox excretion (Lhyp-Lox vs. Mhyp-Lox vs. Hhyp-Lox, P <0.05), and the linear dose-response equation was: Uox (mg ¿d(-1)) = 5.62 + 2.10 x g hyp intake/d (r(2) = 0.56; P <0.001). Increasing oxalate intake from 13 to 93 mg/100g DM did not affect Uox excretion, but resulted in an increase in fecal oxalate output (P <0.001) and positive oxalate balance (32.20 ± 2.06 mg¿d(-1)). The results indicate that the intestinal absorption of the supplemental oxalate, and thereby its contribution to Uox, was low (5.90 ± 5.24%). Relevant increases in endogenous Uox excretion were achieved by increasing dietary hyp intake. The hyp-containing protein sources should be minimized in Ca ox urolith preventative diets until their effect on Uox excretion is tested. The oxalate content (up to 93 mg/100g DM) in a diet with moderate Ca content does not contribute to Uox content.
In vitro selection and characterization of putative probiotics isolated from the gut of Acipenser baerii (Brandt, 1869)
Geraylou, Z. ; Vanhove, M.P.M. ; Souffreau, C. ; Rurangwa, E. ; Buyse, J. ; Ollevier, F. - \ 2014
Aquaculture Research 45 (2014)2. - ISSN 1355-557X - p. 341 - 352.
lactic-acid bacteria - gastrointestinal-tract - fish pathogens - intestinal microbiota - growth-performance - aquaculture - marine - lactobacillus - prevention - tolerance
To select and characterize potential probiotic bacteria from the gut microbiota of Siberian sturgeon (Acipenser baerii), 129 strains isolated from the hindgut were screened for antagonistic activity against five fish pathogens. Ten isolates showed antagonism towards three or more pathogens. Nine of these isolates were Gram-positive, belonging to Lactococcus (seven) and Bacillus (two), and a single strain belonging to the Gram-negative Citrobacter. These inhibitory isolates were identified using genetic, phentotypic and biochemical traits, and further characterized by in vitro tests assessing the adhesion and growth in mucus and resistance to gastric and intestinal fluids. The candidate probiotics were determined to be non-pathogenic through an in vivo study. Based on these assays, Lactococcus lactis ssp. lactis STG45 and STG81 showed the broadest inhibitory potential, a high viability in simulated gastrointestinal juice and the highest adhesion capacity to mucus. They were therefore selected as the most promising candidate probiotics. This is the first study screening probiotics among the gut microflora of Siberian sturgeon.
Human milk: a source of more life than we imagine
Jeurink, P.V. ; Bergenhenegouwen, J. van; Jimenez, E. ; Knippels, L.M.J. ; Fernandez, L. ; Garssen, J. ; Knol, J. ; Rodriguez, J.M. ; Martin, R. - \ 2013
Beneficial Microbes 4 (2013)1. - ISSN 1876-2883 - p. 17 - 30.
lactic-acid bacteria - human breast-milk - fragment-length-polymorphism - human skin microbiome - healthy women - infectious mastitis - dendritic cells - infant gut - staphylococcus-epidermidis - intestinal microbiota
The presence of bacteria in human milk has been acknowledged since the seventies. For a long time, microbiological analysis of human milk was only performed in case of infections and therefore the presence of non-pathogenic bacteria was yet unknown. During the last decades, the use of more sophisticated culture-dependent and -independent techniques, and the steady development of the -omic approaches are opening up the new concept of the 'milk microbiome', a complex ecosystem with a greater diversity than previously anticipated. In this review, possible mechanisms by which bacteria can reach the mammary gland (contamination versus active migration) are discussed. In addition, the potential roles of human milk for both infant and maternal health are summarised. A better understanding of the link between the milk microbiome and health benefit, the potential factors influencing this relationship and whether or not it can be influenced by nutrition is required to open new avenues in the field of pregnancy and lactation.
Microbial Community Structure of Three Traditional Zambian Fermented Products: Mabisi, Chibwantu and Munkoyo
Schoustra, S.E. ; Kasase, C. ; Toarta, C. ; Kassen, R. ; Poulain, A.J. - \ 2013
PLoS ONE 8 (2013)5. - ISSN 1932-6203
lactic-acid bacteria - adaptive radiation - ecology - foods - diversity - microorganisms - fermentations - systems - africa - safety
Around the world, raw materials are converted into fermented food products through microbial and enzymatic activity. Products are typically produced using a process known as batch culture, where small volumes of an old culture are used to initiate a fresh culture. Repeated over many years, and provided samples are not shared among producers, batch culture techniques allow for the natural evolution of independent microbial ecosystems. While these products form an important part of the diets of many people because of their nutritional, organoleptic and food safety properties, for many traditional African fermented products the microbial communities responsible for fermentation are largely unknown. Here we describe the microbial composition of three traditional fermented non-alcoholic beverages that are widely consumed across Zambia: the milk based product Mabisi and the cereal based products Munkoyo and Chibwantu. Using culture and non-culture based techniques, we found that six to eight lactic acid bacteria predominate in all products. We then used this data to investigate in more detail the factors affecting community structure. We found that products made from similar raw materials do not harbor microbial communities that are more similar to each other than those made from different raw materials. We also found that samples from the same product taken at the same location were as different from each other in terms of microbial community structure and composition, as those from geographically very distant locations. These results suggest that microbial community structure in these products is neither a simple consequence of the raw materials used, nor the particular suite of microbes available in the environment but that anthropogenic variables (e. g., competition among sellers or organoleptic preferences by different tribes) are important in shaping the microbial community structures.