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Andrade MJ, Thorsen L, Rodríguez A, Córdoba JJ, Jespersen L. Inhibition of ochratoxigenic moulds by Debaryomyces hansenii strains for biopreservation of dry-cured meat products. Int J Food Microbiol 2014; 170:70-7. [DOI: 10.1016/j.ijfoodmicro.2013.11.004] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2013] [Revised: 10/29/2013] [Accepted: 11/04/2013] [Indexed: 01/09/2023]
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52
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Adimpong DB, Nielsen DS, Sørensen KI, Vogensen FK, Sawadogo-Lingani H, Derkx PMF, Jespersen L. Lactobacillus delbrueckii
subsp. jakobsenii subsp. nov., isolated from dolo wort, an alcoholic fermented beverage in Burkina Faso. Int J Syst Evol Microbiol 2013; 63:3720-3726. [DOI: 10.1099/ijs.0.048769-0] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Lactobacillus delbrueckii
is divided into five subspecies based on phenotypic and genotypic differences. A novel isolate, designated ZN7a-9T, was isolated from malted sorghum wort used for making an alcoholic beverage (dolo) in Burkina Faso. The results of 16S rRNA gene sequencing, DNA–DNA hybridization and peptidoglycan cell-wall structure type analyses indicated that it belongs to the species
L. delbrueckii
. The genome sequence of isolate ZN7a-9T was determined by Illumina-based sequencing. Multilocus sequence typing (MLST) and split-decomposition analyses were performed on seven concatenated housekeeping genes obtained from the genome sequence of strain ZN7a-9T together with 41 additional
L. delbrueckii
strains. The results of the MLST and split-decomposition analyses could not establish the exact subspecies of
L. delbrueckii
represented by strain ZN7a-9T as it clustered with
L. delbrueckii
strains unassigned to any of the recognized subspecies of
L. delbrueckii
. Strain ZN7a-9T additionally differed from the recognized type strains of the subspecies of
L. delbrueckii
with respect to its carbohydrate fermentation profile. In conclusion, the cumulative results indicate that strain ZN7a-9T represents a novel subspecies of
L. delbrueckii
closely related to
Lactobacillus delbrueckii subsp. lactis
and
Lactobacillus delbrueckii subsp. delbrueckii
for which the name
Lactobacillus delbrueckii
subsp. jakobsenii subsp. nov. is proposed. The type strain is ZN7a-9T = DSM 26046T = LMG 27067T.
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Affiliation(s)
- David B. Adimpong
- Chr. Hansen A/S, Discovery Department, 10-12 Bøge Allé, DK-2970 Hørsholm, Denmark
- University of Copenhagen, Faculty of Science, Department of Food Science, Rolighedsvej 30, DK-1958, Frederiksberg C, Denmark
| | - Dennis S. Nielsen
- University of Copenhagen, Faculty of Science, Department of Food Science, Rolighedsvej 30, DK-1958, Frederiksberg C, Denmark
| | - Kim I. Sørensen
- Chr. Hansen A/S, Discovery Department, 10-12 Bøge Allé, DK-2970 Hørsholm, Denmark
| | - Finn K. Vogensen
- University of Copenhagen, Faculty of Science, Department of Food Science, Rolighedsvej 30, DK-1958, Frederiksberg C, Denmark
| | - Hagrétou Sawadogo-Lingani
- Département Technologie Alimentaire/IRSAT/CNRST, 03 BP 7047, Ouagadougou, Burkina Faso
- University of Copenhagen, Faculty of Science, Department of Food Science, Rolighedsvej 30, DK-1958, Frederiksberg C, Denmark
| | - Patrick M. F. Derkx
- Chr. Hansen A/S, Discovery Department, 10-12 Bøge Allé, DK-2970 Hørsholm, Denmark
| | - Lene Jespersen
- University of Copenhagen, Faculty of Science, Department of Food Science, Rolighedsvej 30, DK-1958, Frederiksberg C, Denmark
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53
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Ramos CL, Thorsen L, Schwan RF, Jespersen L. Strain-specific probiotics properties of Lactobacillus fermentum, Lactobacillus plantarum and Lactobacillus brevis isolates from Brazilian food products. Food Microbiol 2013; 36:22-9. [DOI: 10.1016/j.fm.2013.03.010] [Citation(s) in RCA: 182] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2012] [Revised: 02/15/2013] [Accepted: 03/27/2013] [Indexed: 10/27/2022]
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Jespersen L, Abildstrom SZ, Hvelplund A, Galatius S, Madsen JK, Pedersen F, Hojberg S, Prescott E. Symptoms of angina pectoris increase the probability of disability pension and premature exit from the workforce even in the absence of obstructive coronary artery disease. Eur Heart J 2013; 34:3294-303. [DOI: 10.1093/eurheartj/eht395] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
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55
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Jespersen L, Abildstroem SZ, Hvelplund A, Prescott E. Suspected angina pectoris increases the risks of disability pension and premature exit from the workforce irrespective of the presence of coronary artery disease. Eur Heart J 2013. [DOI: 10.1093/eurheartj/eht309.p4006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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56
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Parent EC, Buyks D, Clough J, Jespersen L, Gibson J, Lessard J. Therapy objectives, treatments modalities and outcomes used by physiotherapists for adolescent idiopathic scoliosis in Alberta, Canada. Scoliosis 2013. [PMCID: PMC3675414 DOI: 10.1186/1748-7161-8-s1-o14] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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57
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Greppi A, Rantisou K, Padonou W, Hounhouigan J, Jespersen L, Jakobsen M, Cocolin L. Yeast dynamics during spontaneous fermentation of mawè and tchoukoutou, two traditional products from Benin. Int J Food Microbiol 2013; 165:200-7. [PMID: 23756236 DOI: 10.1016/j.ijfoodmicro.2013.05.004] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2013] [Revised: 04/28/2013] [Accepted: 05/03/2013] [Indexed: 01/04/2023]
Abstract
Mawè and tchoukoutou are two traditional fermented foods largely consumed in Benin, West Africa. Their preparations remain as a house art and they are the result of spontaneous fermentation processes. In this study, dynamics of the yeast populations occurring during spontaneous fermentations of mawè and tchoukoutou were investigated using both culture-dependent and -independent approaches. For each product, two productions were followed. Samples were taken at different fermentation times and yeasts were isolated, resulting in the collection of 177 isolates. They were identified by the PCR-DGGE technique followed by the sequencing of the D1/D2 domain of the 26S rRNA gene. The predominant yeast species identified were typed by rep-PCR. Candida krusei was the predominant yeast species in mawè fermentation followed by Candida glabrata and Kluyveromyces marxianus. Other yeast species were detected in lower numbers. The yeast successions that took place during mawè fermentation lead to a final population comprising Saccharomyces cerevisiae, C. krusei and K. marxianus. The yeast populations dominating the fermentation of tchoukoutou were found to consist of S. cerevisiae, almost exclusively. Other yeast species were detected in the early stages of fermentation. For the predominant species a succession of biotypes was demonstrated by rep-PCR for the fermentation of both products. The direct analysis at DNA and RNA levels in the case of mawè did not reveal any other species except those already identified by culture-based analysis. On the other hand, for tchoukoutou, four species were identified that were not detected by the culture-based approach. The spontaneous fermentation of mawè and tchoukoutou in the end were dominated by a few autochthonous species.
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Affiliation(s)
- Anna Greppi
- Università di Torino, Dipartimento di Scienze Agrarie, Forestali e Alimentari, Via Leonardo da Vinci 44, 10095 Grugliasco, Torino Italy
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58
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Greppi A, Rantsiou K, Padonou W, Hounhouigan J, Jespersen L, Jakobsen M, Cocolin L. Determination of yeast diversity in ogi, mawè, gowé and tchoukoutou by using culture-dependent and -independent methods. Int J Food Microbiol 2013; 165:84-8. [PMID: 23727651 DOI: 10.1016/j.ijfoodmicro.2013.05.005] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2013] [Revised: 04/28/2013] [Accepted: 05/03/2013] [Indexed: 12/21/2022]
Abstract
The maize based ogi and mawè and the sorghum based gowé and tchoukoutou are traditional, spontaneously fermented products widely consumed by the population of Benin (West Africa). Yeast occurrence in the products, as sold on local markets at different locations, was studied using a combination of culture-dependent and independent methods. Number of yeasts is varied from 3.75 log10 colony forming units (cfu)/g for ogi to 5.60 log10 cfu/g for tchoukoutou. Isolated yeasts (236) were identified based on different migration profiles on denaturing gradient gel electrophoresis (DGGE) and 26S rRNA gene sequencing. Candida krusei was the yeast most frequently isolated with strongest predominance in the maize based products. Other predominant yeast present at equal or lower incidence were Clavispora lusitaniae and Saccharomyces cerevisiae in ogi and mawè, Cl. lusitaniae, Candida tropicalis and Kluyveromyces marxianus in gowè and Cl. lusitaniae, S. cerevisiae and Candida rugosa in tchoukoutou. Grouping of C. krusei isolates (164) by rep-PCR analysis indicated that several biotypes were involved in fermentation of the four products. The DGGE analysis on the DNA directly extracted from the food matrices demonstrated the presence of Dekkera bruxellensis and Debaryomyces hansenii, not detected by the culture-based approach. This is the first study combining culture-dependent and independent methods to reveal predominant yeast species and biotypes in traditional foods from Benin.
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Affiliation(s)
- Anna Greppi
- Università di Torino, Dipartimento di Scienze Agrarie, Forestali e Alimentari, Via Leonardo da Vinci 44, 10095, Grugliasco, Torino, Italy
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59
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Gori K, Ryssel M, Arneborg N, Jespersen L. Isolation and identification of the microbiota of Danish farmhouse and industrially produced surface-ripened cheeses. Microb Ecol 2013; 65:602-615. [PMID: 23224222 PMCID: PMC3621994 DOI: 10.1007/s00248-012-0138-3] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/30/2012] [Accepted: 10/22/2012] [Indexed: 06/01/2023]
Abstract
For studying the microbiota of four Danish surface-ripened cheeses produced at three farmhouses and one industrial dairy, both a culture-dependent and culture-independent approach were used. After dereplication of the initial set of 433 isolates by (GTG)5-PCR fingerprinting, 217 bacterial and 25 yeast isolates were identified by sequencing of the 16S rRNA gene or the D1/D2 domain of the 26S rRNA gene, respectively. At the end of ripening, the cheese core microbiota of the farmhouse cheeses consisted of the mesophilic lactic acid bacteria (LAB) starter cultures Lactococcus lactis subsp. lactis and Leuconostoc mesenteorides as well as non-starter LAB including different Lactobacillus spp. The cheese from the industrial dairy was almost exclusively dominated by Lb. paracasei. The surface bacterial microbiota of all four cheeses were dominated by Corynebacterium spp. and/or Brachybacterium spp. Brevibacterium spp. was found to be subdominant compared to other bacteria on the farmhouse cheeses, and no Brevibacterium spp. was found on the cheese from the industrial dairy, even though B. linens was used as surface-ripening culture. Moreover, Gram-negative bacteria identified as Alcalignes faecalis and Proteus vulgaris were found on one of the farmhouse cheeses. The surface yeast microbiota consisted primarily of one dominating species for each cheese. For the farmhouse cheeses, the dominant yeast species were Yarrowia lipolytica, Geotrichum spp. and Debaryomyces hansenii, respectively, and for the cheese from the industrial dairy, D. hansenii was the dominant yeast species. Additionally, denaturing gradient gel electrophoresis (DGGE) analysis revealed that Streptococcus thermophilus was present in the farmhouse raw milk cheese analysed in this study. Furthermore, DGGE bands corresponding to Vagococcus carniphilus, Psychrobacter spp. and Lb. curvatus on the cheese surfaces indicated that these bacterial species may play a role in cheese ripening.
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Affiliation(s)
- Klaus Gori
- Department of Food Science, Food Microbiology, Faculty of Life Sciences, University of Copenhagen, Frederiksberg C, Denmark.
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60
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Jespersen L, Jakobsen M. USE OF FLOW CYTOMETRY FOR RAPID ESTIMATION OF INTRACELLULAR EVENTS IN BREWING YEASTS. Journal of the Institute of Brewing 2013. [DOI: 10.1002/j.2050-0416.1994.tb00837.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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61
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Guldfeldt LU, Arneborg N, Siegumfeldt H, Jespersen L. RELATIONSHIP BETWEEN YEAST CELL PROLIFERATION AND INTRACELLULAR ESTERASE ACTIVITY DURING BREWING FERMENTATIONS. Journal of the Institute of Brewing 2013. [DOI: 10.1002/j.2050-0416.1998.tb01005.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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62
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Owusu-Kwarteng J, Tano-Debrah K, Akabanda F, Nielsen DS, Jespersen L. Partial Characterization of Bacteriocins Produced by Lactobacillus reuteri 2-20B and Pediococcus acidilactici 0-11A Isolated from Fura, a Millet-Based Fermented Food in Ghana. ACTA ACUST UNITED AC 2013. [DOI: 10.5539/jfr.v2n1p50] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Cell-free supernatants (CFS) produced by 369 LAB strains previously isolated from fura and identified based on sequencing of their 16S rRNA genes were screened for their antagonistic activities against pathogenic bacteria including<em> Bacillus cereus</em> PA24, <em>Escherichia coli </em>SKN 541, <em>Enterococcus faecalis</em> 103907 CIP, <em>Staphylococcus aureus</em> ATCC 19095 and <em>Listeria</em> <em>monocytogenes</em> Scott A, using the agar well diffusion method. Bacteriocins of <em>Lactobacillus</em> <em>reuteri</em> 2-20B and <em>Pediococcus acidilactici</em> 0-11A were further evaluated for their stability when subjected to a range of pH conditions, enzymatic and heat treatments. Growth and bacteriocin production rates as well as influence of media composition on bacteriocin production were also evaluated. Cell free supernatants of <em>Lb</em>. <em>reuteri</em> and <em>Pd</em>. <em>acidilactici</em> strains exhibited the widest inhibitory activities whereas CFS of <em>Lb</em>. <em>fermentum</em> exhibited the least inhibitory activity towards the tested pathogens. Bacteriocins of <em>Lb</em>. <em>reuteri</em> 2-20B and <em>Pd</em>. <em>acidilactici</em> 0-11A retained their antibacterial activities over a wide range of pH. Whereas the antimicrobial activity of <em>Lb</em>. <em>reuteri</em> 2-20B was lost after being subjected to temperature of 90°C for 1 h, CFS of <em>Pd</em>. <em>acidilactici</em> 0-11A remained stable after autoclaving at 121°C for 15 min. Again, the antimicrobial activities of both <em>Lb</em>. <em>reuteri</em> 2-20B and <em>Pd</em>. <em>acidilactici</em> 0-11A were lost when the CFSs were subjected to the action of proteolytic enzymes but remained active under the actions of catalase, lipase and a-amylase. Production of bacteriocins by both <em>Lb</em>. <em>reuteri</em> 2-20B and <em>Pd</em>. <em>acidilactici</em> 0-11A were growth associated and influeced by media composition.
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63
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Knudsen A, van Zanten GC, Jensen SL, Forssten SD, Saarinen M, Lahtinen SJ, Bandsholm O, Svensson B, Jespersen L, Blennow A. Comparative fermentation of insoluble carbohydrates in an in vitro human feces model spiked withLactobacillus acidophilusNCFM. STARCH-STARKE 2012. [DOI: 10.1002/star.201200091] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
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64
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Akabanda F, Owusu-Kwarteng J, Tano-Debrah K, Glover RLK, Nielsen DS, Jespersen L. Taxonomic and molecular characterization of lactic acid bacteria and yeasts in nunu, a Ghanaian fermented milk product. Food Microbiol 2012; 34:277-83. [PMID: 23541194 DOI: 10.1016/j.fm.2012.09.025] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2012] [Revised: 09/26/2012] [Accepted: 09/27/2012] [Indexed: 10/27/2022]
Abstract
Produced from raw unpasteurized milk, nunu is a spontaneously fermented yoghurt-like product made in Ghana and other parts of West Africa. Despite the importance of nunu in the diet of many Africans, there is currently only limited information available on the microorganisms associated with nunu processing. With the aim of obtaining a deeper understanding of the process and as a first step towards developing starter cultures with desired technological properties for nunu production, a microbiological characterization of nunu processing in three different towns in the Upper East region of Ghana, namely Bolgatanga, Paga and Navrongo, was carried out. Lactic acid bacteria (LAB) and yeasts associated with nunu processing were isolated and identified using a combination of pheno- and genotypic methods including morphological and carbohydrate fermentation tests, (GTG)5-based rep-PCR, multiplex PCR, and 16S and 26S rRNA gene sequencing. The LAB counts during nunu processing increased from 4.5 ± 0.4 log cfu/ml at 0 h to 8.7 ± 1.8 log cfu/ml at 24 h of fermentation while yeasts counts increased from 2.8 ± 1.2 log cfu/ml at 0 h to 5.8 ± 0.5 log cfu/ml by the end of fermentation. Lactobacillus fermentum was the dominant LAB throughout the fermentations with Lactobacillus plantarum and Leuconostoc mesenteroides playing prominent roles during the first 6-8 h of fermentation as well. Less frequently isolated LAB included Lactobacillus helveticus, Enterococcus faecium, Enterococcus italicus, Weissella confusa and a putatively novel Lactococcus spp. The yeasts involved were identified as Candida parapsilosis, Candida rugosa, Candida tropicalis, Galactomyces geotrichum, Pichia kudriavzevii and Saccharomyces cerevisiae with P. kudriavzevii and S. cerevisiae being the dominant yeast species.
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Affiliation(s)
- Fortune Akabanda
- Department of Nutrition and Food Science, University of Ghana, Legon, Ghana
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65
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van Zanten GC, Knudsen A, Röytiö H, Forssten S, Lawther M, Blennow A, Lahtinen SJ, Jakobsen M, Svensson B, Jespersen L. The effect of selected synbiotics on microbial composition and short-chain fatty acid production in a model system of the human colon. PLoS One 2012; 7:e47212. [PMID: 23082149 PMCID: PMC3474826 DOI: 10.1371/journal.pone.0047212] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2012] [Accepted: 09/10/2012] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND Prebiotics, probiotics and synbiotics can be used to modulate both the composition and activity of the gut microbiota and thereby potentially affecting host health beneficially. The aim of this study was to investigate the effects of eight synbiotic combinations on the composition and activity of human fecal microbiota using a four-stage semicontinuous model system of the human colon. METHODS AND FINDINGS Carbohydrates were selected by their ability to enhance growth of the probiotic bacteria Lactobacillus acidophilus NCFM (NCFM) and Bifidobacterium animalis subsp. lactis Bl-04 (Bl-04) under laboratory conditions. The most effective carbohydrates for each probiotic were further investigated, using the colonic model, for the ability to support growth of the probiotic bacteria, influence the composition of the microbiota and stimulate formation of short-chain fatty acids (SCFA).The following combinations were studied: NCFM with isomaltulose, cellobiose, raffinose and an oat β-glucan hydrolysate (OBGH) and Bl-04 with melibiose, xylobiose, raffinose and maltotriose. All carbohydrates showed capable of increasing levels of NCFM and Bl-04 during fermentations in the colonic model by 10(3)-10(4) fold and 10-10(2) fold, respectively. Also the synbiotic combinations decreased the modified ratio of Bacteroidetes/Firmicutes (calculated using qPCR results for Bacteroides-Prevotella-Porphyromonas group, Clostridium perfringens cluster I, Clostridium coccoides - Eubacterium rectale group and Clostridial cluster XIV) as well as significantly increasing SCFA levels, especially acetic and butyric acid, by three to eight fold, as compared to the controls. The decreases in the modified ratio of Bacteroidetes/Firmicutes were found to be correlated to increases in acetic and butyric acid (p=0.04 and p=0.03, respectively). CONCLUSIONS The results of this study show that all synbiotic combinations investigated are able to shift the predominant bacteria and the production of SCFA of fecal microbiota in a model system of the human colon, thereby potentially being able to manipulate the microbiota in a way connected to human health.
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Affiliation(s)
- Gabriella C van Zanten
- Department of Food Science, Faculty of Life Sciences, University of Copenhagen, Frederiksberg, Denmark.
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66
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Gori K, Sørensen LM, Petersen MA, Jespersen L, Arneborg N. Debaryomyces hansenii strains differ in their production of flavor compounds in a cheese-surface model. Microbiologyopen 2012; 1:161-8. [PMID: 22950022 PMCID: PMC3426413 DOI: 10.1002/mbo3.11] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2011] [Revised: 01/04/2012] [Accepted: 01/09/2012] [Indexed: 12/04/2022] Open
Abstract
Flavor production among 12 strains of Debaryomyces hansenii when grown on a simple cheese model mimicking a cheese surface was investigated by dynamic headspace sampling followed by gas chromatography-mass spectrometry. The present study confirmed that D. hansenii possess the ability to produce important cheese flavor compounds, primarily branched-chain aldehydes and alcohols, and thus important for the final cheese flavor. Quantification of representative aldehydes (2-Methylpropanal, 3-Methylbutanal) and alcohols (2-Methyl-1-propanol, 3-Methyl-1-butanol, and 3-Methyl-3-buten-1-ol) showed that the investigated D. hansenii strains varied significantly with respect to production of these flavor compounds. Contrary to the alcohols (2-Methyl-1-propanol, 3-Methyl-1-butanol, and 3-Methyl-3-buten-1-ol), the aldehydes (2-Methylpropanal, 3-Methylbutanal) were produced by the D. hansenii strains in concentrations higher than their sensory threshold values, and thus seemed more important than alcohols for cheese flavor. These results show that D. hansenii strains may have potential to be applied as cultures for increasing the nutty/malty flavor of cheese due to their production of aldehydes. However, due to large strain variations, production of flavor compounds has to be taken into consideration for selection of D. hansenii strains as starter cultures for cheese production.
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Affiliation(s)
- Klaus Gori
- Department of Food Science, Food Microbiology, Faculty of Life Sciences, University of CopenhagenRolighedsvej 30, DK-1958 Frederiksberg C, Denmark
| | - Louise Marie Sørensen
- Department of Food Science, Food Microbiology, Faculty of Life Sciences, University of CopenhagenRolighedsvej 30, DK-1958 Frederiksberg C, Denmark
| | - Mikael Agerlin Petersen
- Department of Food Science, Quality and Technology, Faculty of Life Sciences, University of CopenhagenRolighedsvej 30, DK-1958 Frederiksberg C, Denmark
| | - Lene Jespersen
- Department of Food Science, Food Microbiology, Faculty of Life Sciences, University of CopenhagenRolighedsvej 30, DK-1958 Frederiksberg C, Denmark
| | - Nils Arneborg
- Department of Food Science, Food Microbiology, Faculty of Life Sciences, University of CopenhagenRolighedsvej 30, DK-1958 Frederiksberg C, Denmark
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Pedersen LL, Owusu-Kwarteng J, Thorsen L, Jespersen L. Biodiversity and probiotic potential of yeasts isolated from Fura, a West African spontaneously fermented cereal. Int J Food Microbiol 2012; 159:144-51. [PMID: 23072700 DOI: 10.1016/j.ijfoodmicro.2012.08.016] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2012] [Revised: 07/10/2012] [Accepted: 08/22/2012] [Indexed: 12/12/2022]
Abstract
Fura is a spontaneously fermented pearl millet product consumed in West Africa. The yeast species involved in the fermentation were identified by pheno- and genotypic methods to be Candida krusei, Kluyveromyces marxianus, Candida tropicalis, Candida rugosa, Candida fabianii, Candida norvegensis and Trichosporon asahii. C. krusei and K. marxianus were found to be the dominant species. Survival in pH 2.5 or in the presence of bile salts (0.3% (w/v) oxgall) and growth at 37°C were independently determined as indicators of the survival potential of the isolates during passage through the human gastrointestinal tract. Selected yeast species isolates were assessed for their probiotic potential. All of the examined yeast isolates survived and grew at human gastrointestinal conditions in pH 2.5, 0.3% (w/v) oxgall at 37°C. The effect on the transepithelial electrical resistance (TEER) across polarized monolayers of intestinal epithelial cells of human (Caco-2) and porcine (IPEC-J2) origin, were determined. The Caco-2 cells and IPEC-J2 cells displayed clearly different relative TEER results. The strains of C. krusei, K. marxianus, C. rugosa and T. asahii were able to increase the relative TEER of Caco-2 monolayers after 48h. In comparison, the relative TEER of IPEC-J2 monolayers decreased when exposed to the same yeasts, even though T. asahii did not differ significantly from Saccharomyces cerevisiae var. boulardii which is used as a human probiotic. C. tropicalis resulted in the largest relative TEER decrease for both the human and the porcine cell model assays. Hyphal growth was observed for C. albicans and C. tropicalis after 48h of incubation with polarized Caco-2 monolayers, whereas this was not the case for the remaining yeast species. In the present study new yeast strains with potential probiotic properties have been isolated to be used potentially as starter cultures for fura production.
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Affiliation(s)
- Line Lindegaard Pedersen
- Department of Food Science, Food Microbiology, Faculty of Sciences, University of Copenhagen, Denmark.
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Llopis S, Querol A, Heyken A, Hube B, Jespersen L, Fernández-Espinar MT, Pérez-Torrado R. Transcriptomics in human blood incubation reveals the importance of oxidative stress response in Saccharomyces cerevisiae clinical strains. BMC Genomics 2012; 13:419. [PMID: 22916735 PMCID: PMC3483181 DOI: 10.1186/1471-2164-13-419] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2012] [Accepted: 08/20/2012] [Indexed: 01/19/2023] Open
Abstract
Background In recent years an increasing number of yeast infections in humans have been related to certain clinical isolates of Saccharomyces cerevisiae. Some clinical strains showed in vivo and in vitro virulence traits and were able to cause death in mice whereas other clinical strains were avirulent. Results In this work, we studied the transcriptional profiles of two S. cerevisiae clinical strains showing virulent traits and two control non-virulent strains during a blood incubation model and detected a specific transcriptional response of clinical strains. This response involves an mRNA levels increase of amino acid biosynthesis genes and especially oxidative stress related genes. We observed that the clinical strains were more resistant to reactive oxygen species in vitro. In addition, blood survival of clinical isolates was high, reaching similar levels to pathogenic Candida albicans strain. Furthermore, a virulent strain mutant in the transcription factor Yap1p, unable to grow in oxidative stress conditions, presented decreased survival levels in human blood compared with the wild type or YAP1 reconstituted strain. Conclusions Our data suggest that this enhanced oxidative stress response in virulent clinical isolates, presumably induced in response to oxidative burst from host defense cells, is important to increase survival in human blood and can help to infect and even produce death in mice models.
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Affiliation(s)
- Silvia Llopis
- Instituto de Agroquímica y Tecnología de los Alimentos, IATA-CSIC, Burjassot, Spain
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Adimpong DB, Nielsen DS, Sørensen KI, Derkx PMF, Jespersen L. Genotypic characterization and safety assessment of lactic acid bacteria from indigenous African fermented food products. BMC Microbiol 2012; 12:75. [PMID: 22594449 PMCID: PMC3463448 DOI: 10.1186/1471-2180-12-75] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2011] [Accepted: 05/17/2012] [Indexed: 11/25/2022] Open
Abstract
Background Indigenous fermented food products play an essential role in the diet of millions of Africans. Lactic acid bacteria (LAB) are among the predominant microbial species in African indigenous fermented food products and are used for different applications in the food and biotechnology industries. Numerous studies have described antimicrobial susceptibility profiles of LAB from different parts of the world. However, there is limited information on antimicrobial resistance profiles of LAB from Africa. The aim of this study was to characterize 33 LAB previously isolated from three different African indigenous fermented food products using (GTG)5-based rep-PCR, sequencing of the 16S rRNA gene and species-specific PCR techniques for differentiation of closely related species and further evaluate their antibiotic resistance profiles by the broth microdilution method and their haemolytic activity on sheep blood agar plates as indicators of safety traits among these bacteria. Results Using molecular biology based methods and selected phenotypic tests such as catalase reaction, CO2 production from glucose, colonies and cells morphology, the isolates were identified as Lactobacillus delbrueckii, Lactobacillus fermentum, Lactobacillus ghanensis, Lactobacillus plantarum, Lactobacillus salivarius, Leuconostoc pseudomesenteroides, Pediococcus acidilactici, Pediococcus pentosaceus and Weissella confusa. The bacteria were susceptible to ampicillin, chloramphenicol, clindamycin and erythromycin but resistant to vancomycin, kanamycin and streptomycin. Variable sensitivity profiles to tetracycline and gentamicin was observed among the isolates with Lb. plantarum, Lb. salivarius, W. confusa (except strain SK9-5) and Lb. fermentum strains being susceptible to tetracycline whereas Pediococcus strains and Lb. ghanensis strains were resistant. For gentamicin, Leuc. pseudomesenteroides, Lb. ghanensis and Ped. acidilactici strains were resistant to 64 mg/L whereas some W. confusa and Lb. plantarum strains had a MIC value of 16 mg/L and 32 mg/L respectively. No β-haemolytic activity was observed, however, α-haemolytic activity was observed in 27% (9) of the strains comprising Lb. salivarius (6), W. confusa (2) and Lb. delbrueckii (1) isolates. Conclusions The resistance to kanamycin and vancomycin is probably an intrinsic feature since similar observations were reported in the literature for LAB. Low prevalence of pathogenicity indicator traits were observed among the isolates especially with the presence of poor haemolytic activities and they could therefore be considered as interesting candidates for selection of starter cultures or probiotics for different applications.
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Affiliation(s)
- David B Adimpong
- Department of Food Science, University of Copenhagen, Faculty of Life Sciences, Rolighedsvej 30, Frederiksberg C, Denmark.
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Abban S, Jakobsen M, Jespersen L. Attachment behaviour of Escherichia coli K12 and Salmonella Typhimurium P6 on food contact surfaces for food transportation. Food Microbiol 2012; 31:139-47. [PMID: 22608216 DOI: 10.1016/j.fm.2012.04.003] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2012] [Revised: 04/03/2012] [Accepted: 04/03/2012] [Indexed: 11/15/2022]
Abstract
The role of cargo container lining materials aluminium, a fibre reinforced plastic (FRP) and stainless steel in bacterial cross contamination during transport was assessed. For this, attachment and detachment of Escherichia coli K12 and Salmonella Typhimurium P6 on the three surfaces in the absence or presence of residues were evaluated. Observations were correlated with water contact angles of the materials (hydrophobicity) and roughness profile (R(a)). Attachment of the organisms was negatively correlated to the hydrophobicity of the three materials with r = -0.869 and -0.861 for E. coli K12 and S. Typhimurium P6 respectively. Correlation with roughness average was poor; r = -0.425 and -0.413 respectively for E. coli K12 and S. Typhimurium P6. Presence of residue caused significant reduction (p < 0.05) in the levels of bacteria attached to all materials, but made attached bacteria significantly more difficult to detach by either of two rinsing systems from all three surfaces. Explanation for these observations could be made in part from scanning electron micrographs which showed significantly more bacteria sitting on patches of residue when it was introduced to the surfaces, compared to the bare material sections of the same surfaces. We report these observations for the first time for aluminium and the FRP material and in part for stainless steel. The S. Typhimurium P6 strain also had significantly higher level of attachment than the E. coli K12 strain. Our findings show that food residue and soils affect the extent and amount of bacteria attaching to abiotic surfaces by altering the surface contact properties for the bacteria. Physicochemical properties like hydrophobicity appear to be a better basis for material selection for hygienic design of containers, than the traditional use of R(a).
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Affiliation(s)
- Stephen Abban
- Department of Food Science, Centre for Advanced Food Studies (LMC), Faculty of Life Sciences, University of Copenhagen, Rolighedsvej 30, 4, DK-1958 Frederiksberg C, Denmark.
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Poli VFS, Thorsen L, Olesen I, Wik MT, Jespersen L. Differentiation of the virulence potential of Campylobacter jejuni strains by use of gene transcription analysis and a Caco-2 assay. Int J Food Microbiol 2012; 155:60-8. [DOI: 10.1016/j.ijfoodmicro.2012.01.019] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2011] [Revised: 01/20/2012] [Accepted: 01/22/2012] [Indexed: 01/05/2023]
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Sørensen LM, Gori K, Petersen MA, Jespersen L, Arneborg N. Flavour compound production by Yarrowia lipolytica, Saccharomyces cerevisiae and Debaryomyces hansenii in a cheese-surface model. Int Dairy J 2011. [DOI: 10.1016/j.idairyj.2011.06.005] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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73
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Rantsiou K, Mataragas M, Jespersen L, Cocolin L. Understanding the behavior of foodborne pathogens in the food chain: New information for risk assessment analysis. Trends Food Sci Technol 2011. [DOI: 10.1016/j.tifs.2011.03.002] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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74
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Gori K, Knudsen PB, Nielsen KF, Arneborg N, Jespersen L. Alcohol-based quorum sensing plays a role in adhesion and sliding motility of the yeast Debaryomyces hansenii. FEMS Yeast Res 2011; 11:643-52. [DOI: 10.1111/j.1567-1364.2011.00755.x] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2011] [Revised: 09/04/2011] [Accepted: 09/05/2011] [Indexed: 11/30/2022] Open
Affiliation(s)
- Klaus Gori
- Department of Food Science, Food Microbiology; Faculty of Life Sciences; University of Copenhagen; Frederiksberg; Denmark
| | - Peter B. Knudsen
- Department of Systems Biology; Center for Microbial Biotechnology; Technical University of Denmark; Lyngby; Denmark
| | - Kristian F. Nielsen
- Department of Systems Biology; Center for Microbial Biotechnology; Technical University of Denmark; Lyngby; Denmark
| | - Nils Arneborg
- Department of Food Science, Food Microbiology; Faculty of Life Sciences; University of Copenhagen; Frederiksberg; Denmark
| | - Lene Jespersen
- Department of Food Science, Food Microbiology; Faculty of Life Sciences; University of Copenhagen; Frederiksberg; Denmark
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75
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Clerici⁎ M, Rizzardini G, Cossu M, Jespersen L, Calder P, Eskesen D. Probiotic strains BB-12® and L. casei 431® increase the immune response to an influenza vaccine: A randomized, double-blind, placebo-controlled study. Eur J Pharmacol 2011. [DOI: 10.1016/j.ejphar.2011.09.200] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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76
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Moslehi-Jenabian S, Vogensen FK, Jespersen L. The quorum sensing luxS gene is induced in Lactobacillus acidophilus NCFM in response to Listeria monocytogenes. Int J Food Microbiol 2011; 149:269-73. [PMID: 21784546 DOI: 10.1016/j.ijfoodmicro.2011.06.011] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2010] [Revised: 03/06/2011] [Accepted: 06/19/2011] [Indexed: 10/18/2022]
Abstract
The luxS gene involved in quorum sensing has been shown to control different behaviour of probiotic lactobacilli. In this study we investigated if luxS in Lactobacillus acidophilus NCFM was up-regulated in response to Listeria monocytogenes EGD-e. The two bacterial strains were grown in mono- and co-culture and the growth of both bacteria and the transcriptional level of luxS in L. acidophilus cells were monitored. Contrary to L. acidophilus, the growth of L. monocytogenes was significantly affected by co-cultivation. Transcriptional analysis showed that the expression of luxS increased during exponential growth in L. acidophilus cells with the highest level in the late-exponential growth phase, decreasing in the stationary phase. Following co-cultivation with L. monocytogenes, the transcriptional level of luxS increased significantly in mid-exponential growing cells of L. acidophilus after incubation with viable L. monocytogenes cells and by addition of cell-free culture supernatant of L. monocytogenes, whereas incubation with heat killed cells of L. monocytogenes had no effect on the transcriptional level. This could indicate that the up-regulation of luxS is due to a response to a secreted compound produced by L. monocytogenes cells.
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Affiliation(s)
- Saloomeh Moslehi-Jenabian
- University of Copenhagen, Faculty of Life Sciences, Department of Food Science, Food Microbiology, Rolighedsvej 30, DK-1958 Frederiksberg C, Denmark.
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78
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Weiss G, Rasmussen S, Zeuthen LH, Nielsen BN, Jarmer H, Jespersen L, Frøkiaer H. Lactobacillus acidophilus induces virus immune defence genes in murine dendritic cells by a Toll-like receptor-2-dependent mechanism. Immunology 2011; 131:268-81. [PMID: 20545783 DOI: 10.1111/j.1365-2567.2010.03301.x] [Citation(s) in RCA: 121] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Lactobacilli are probiotics that, among other health-promoting effects, have been ascribed immunostimulating and virus-preventive properties. Certain Lactobacillus spp. have been shown to possess strong interleukin-12 (IL-12) -inducing properties. As IL-12 production depends on the up-regulation of type I interferons (IFNs), we hypothesized that the strong IL-12-inducing capacity of Lactobacillus acidophilus NCFM in murine bone-marrow-derived dendritic cells (DCs) is caused by an up-regulation of IFN-β, which subsequently induces IL-12 and the double-stranded RNA binding Toll-like receptor-3 (TLR-3). The expression of the genes encoding IFN-β, TLR-3, IL-12 and IL-10 in DCs upon stimulation with L. acidophilus NCFM was determined. Lactobacillus acidophilus NCFM induced a much stronger expression of Ifn-β, Il-12 and Il-10 compared with the synthetic double-stranded RNA ligand Poly I:C, whereas the levels of expressed Tlr-3 were similar. Whole genome microarray gene expression analysis revealed that other genes related to viral defence were significantly up-regulated and among the strongest induced genes in DCs stimulated with L. acidophilus NCFM. The ability to induce IFN-β was also detected in another L. acidophilus strain (X37), but was not a property of other probiotic strains tested, i.e. Bifidobacterium bifidum Z9 and Escherichia coli Nissle 1917. The IFN-β expression was markedly reduced in TLR-2(-/-) DCs, dependent on endocytosis, and the major cause of the induction of Il-12 and Tlr-3 in DCs stimulated with L. acidophilus NCFM. Collectively, our results reveal that certain lactobacilli trigger the expression of viral defence genes in DCs in a TLR-2 manner dependent on IFN-β.
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Affiliation(s)
- Gudrun Weiss
- Faculty of Life Sciences, Department of Basic Sciences and Environment, University of Copenhagen, Frederiksberg C, Denmark
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79
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Gori K, Bjørklund MK, Canibe N, Pedersen AØ, Jespersen L. Occurrence and identification of yeast species in fermented liquid feed for piglets. Microb Ecol 2011; 61:146-153. [PMID: 20574824 DOI: 10.1007/s00248-010-9706-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/07/2010] [Accepted: 06/09/2010] [Indexed: 05/29/2023]
Abstract
The major objective of the present study was to investigate the occurrence and identity of yeast species in fermented liquid feed (FLF) used for feeding piglets. In total, 40 different Danish farms were included in the analysis. The preparation and composition of FLF was found to be very heterogeneous with high variations in both yeast counts and yeast species composition. The yeast population varied between 6.0 × 10(3) and 4.2 × 10(7) cfug(-1) with an average yeast count of 8.7 × 10(6) ± 1.1 × 10(7) cfug(-1). A total of 766 yeasts were isolated and identified by conventional and/or molecular typing techniques. The predominant yeast species in the FLF samples were found to be Candida milleri (58.4%), Kazachstania exigua (17.5%), Candida pararugosa (6.40%) and Kazachstania bulderi (5.09%). No clear separation between isolates of C. milleri and Candida humilis could be obtained based on sequencing of the D1/D2 region of the 26S rRNA gene. The combined use of ITS-RFLP analysis and phenotypic criteria did meanwhile suggest a closer relationship with C. milleri than C. humilis.
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Affiliation(s)
- Klaus Gori
- Department of Food Science, Food Microbiology, Faculty of Life Sciences, University of Copenhagen, Rolighedsvej 30, 1958, Frederiksberg C, Denmark
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Canibe N, Pedersen AØ, Jensen BB, Jespersen L. Microbiological and biochemical characterization of fermented liquid feed samples from 40 Danish farms. Livest Sci 2010. [DOI: 10.1016/j.livsci.2010.06.125] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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Olesen I, Jespersen L. Relative gene transcription and pathogenicity of enterohemorrhagic Escherichia coli after long-term adaptation to acid and salt stress. Int J Food Microbiol 2010; 141:248-53. [DOI: 10.1016/j.ijfoodmicro.2010.05.019] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2010] [Revised: 05/18/2010] [Accepted: 05/21/2010] [Indexed: 02/02/2023]
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83
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Weiss G, Jespersen L. Transcriptional Analysis of Genes Associated with Stress and Adhesion in Lactobacillus acidophilus NCFM during the Passage through an in vitro Gastrointestinal Tract Model. J Mol Microbiol Biotechnol 2010; 18:206-14. [DOI: 10.1159/000316421] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
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84
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Nielsen DS, Jakobsen M, Jespersen L. Candida halmiae sp. nov., Geotrichum ghanense sp. nov. and Candida awuaii sp. nov., isolated from Ghanaian cocoa fermentations. Int J Syst Evol Microbiol 2010; 60:1460-1465. [DOI: 10.1099/ijs.0.016006-0] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
During an investigation of the microbiology of Ghanaian cocoa fermentations, a number of yeast isolates with unusual pheno- and genotypic properties representing three possible novel species were isolated. Members of Group A divided by multilateral budding and ascospores were not produced. Group B strains produced true hyphae and ascospores were not produced. Group C representatives divided by budding and formed chains and star-like aggregates. Ascospores were not produced. Sequence analysis of the 26S rRNA gene (D1/D2 region) revealed that the Group A isolates were phylogenetically most closely related to Saturnispora mendoncae (gene sequence similarity 92.4 %), Saturnispora besseyi (88.8 %), Saturnispora saitoi (88.8 %) and Saturnispora ahearnii (88.3 %). Members of Group B were most closely related to representatives of the genera Dipodascus and Galactomyces and the asporogenous genus Geotrichum, but in all cases with 26S rRNA gene (D1/D2 region) similarities below 87 %. For Group C, the most closely related species were Candida rugopelliculosa (92.4 %), Pichia occidentalis (91.6 %) and Pichia exigua (91.9 %). The very low gene sequence similarities obtained for the three groups of isolates clearly indicated that they represented novel species. Repetitive Palindromic PCR (Rep-PCR) of the isolates and their closest phylogenetic relatives confirmed that the new isolates belonged to previously undescribed species. In conclusion, based on the genetic and phenotypic results, the new isolates were considered to represent three novel species, for which the names Candida halmiae (group A, type strain G3T=CBS 11009T=CCUG 56721T); Geotrichum ghanense (group B, type strain G6T=CBS 11010T=CCUG 56722T) and Candida awuaii (group C, type strain G15T=CBS 11011T=CCUG 56723T) are proposed.
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Affiliation(s)
- Dennis S. Nielsen
- Department of Food Science, Food Microbiology, Center for Advanced Food Studies (LMC), Faculty of Life Sciences, University of Copenhagen, Denmark
| | - Mogens Jakobsen
- Department of Food Science, Food Microbiology, Center for Advanced Food Studies (LMC), Faculty of Life Sciences, University of Copenhagen, Denmark
| | - Lene Jespersen
- Department of Food Science, Food Microbiology, Center for Advanced Food Studies (LMC), Faculty of Life Sciences, University of Copenhagen, Denmark
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Jiang L, Olesen I, Andersen T, Fang W, Jespersen L. Survival of Listeria monocytogenes in simulated gastrointestinal system and transcriptional profiling of stress- and adhesion-related genes. Foodborne Pathog Dis 2010; 7:267-74. [PMID: 19899961 DOI: 10.1089/fpd.2009.0361] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Food ingestion is the major route of exposure to the important human pathogen Listeria monocytogenes. An in vitro gastrointestinal model was used to (1) compare the survival rates of L. monocytogenes strains of serotypes 1/2a, 1/2c, and 4b; and (2) examine the transcription of stress- and adhesion-related genes after exposure to the conditions similar to those encountered in the mouth, stomach, and small intestine. None of the L. monocytogenes strains investigated could survive in the gastric juice at pH 2.5 or 3.0. Their survival increased at higher pH (3.5 and 4.0) in the gastric stress. Relative survival of L. monocytogenes serotypes 4b and 1/2a strains were higher than that of serotype 1/2c, suggesting that pathogenicity might be related to the viability in the gastrointestinal tract. The transcription levels of prfA and the general stress-related genes clpC, clpE, and clpP were upregulated after passing through the simulated gastrointestinal tract, whereas that of the adhesion-related gene ami was downregulated. Taken together, this study revealed that L. monocytogenes strains enhanced the expression of stress-related genes and decreased the transcription of adhesion-related gene in order to survive in the diverse microenvironments.
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Affiliation(s)
- Lingli Jiang
- Zhejiang University Institute of Preventive Veterinary Medicine, and Zhejiang Provincial Key Laboratory for Preventive Veterinary Medicine, Hangzhou, Zhejiang, People's Republic of China
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Moslehi-Jenabian S, Pedersen LL, Jespersen L. Beneficial effects of probiotic and food borne yeasts on human health. Nutrients 2010; 2:449-73. [PMID: 22254033 PMCID: PMC3257658 DOI: 10.3390/nu2040449] [Citation(s) in RCA: 140] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2010] [Revised: 03/01/2010] [Accepted: 03/24/2010] [Indexed: 12/13/2022] Open
Abstract
Besides being important in the fermentation of foods and beverages, yeasts have shown numerous beneficial effects on human health. Among these, probiotic effects are the most well known health effects including prevention and treatment of intestinal diseases and immunomodulatory effects. Other beneficial functions of yeasts are improvement of bioavailability of minerals through the hydrolysis of phytate, folate biofortification and detoxification of mycotoxins due to surface binding to the yeast cell wall.
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Affiliation(s)
- Saloomeh Moslehi-Jenabian
- Department of Food Science, Food Microbiology, University of Copenhagen, Rolighedsvej 30, DK-1958 Frederiksberg C, Denmark.
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Olesen I, Thorsen L, Jespersen L. Relative transcription of Listeria monocytogenes virulence genes in liver pâtés with varying NaCl content. Int J Food Microbiol 2010; 141 Suppl 1:S60-8. [PMID: 20206397 DOI: 10.1016/j.ijfoodmicro.2010.01.042] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2009] [Revised: 01/27/2010] [Accepted: 01/29/2010] [Indexed: 01/20/2023]
Abstract
Quantitative real time polymerase chain reaction (qRT PCR) was used to compare the relative transcription of prfA, inlA, sigB and clpC for three Listeria monocytogenes strains after incubation in i) a standard liver pâté versus brain heart infusion (BHI) broth and ii) the standard liver pâté versus three liver pâtés with reduced NaCl content of which one also has been supplied with organic acids (Ca-acetate and Ca-lactate). The three strains (EGD-e: reference strain; O57: more NaCl sensitive; 6896: more NaCl tolerant) were selected out of twelve strains based on their growth in BHI broth adjusted to 6%, 8%, 10% (w/v) NaCl. The three strains were spiked into the liver pâtés (10(9) cfu/g) and the BHI (10(9) cfu/ml) and incubated for 48 h at 7 degrees C; all incubation conditions supported growth of the strains. Extraction of intact listerial RNA from the liver pâtés was complicated by the complexity of the liver pâté matrix. However, a method has been optimized and described, and the quality of RNA extracted from liver pâtés was equal to the quality of RNA extracted from BHI. The amplification efficiencies of the six genes used for the transcription analyses (the four target genes and two reference genes, gap and rpoB) were within the acceptable range from 90% to 110% for all three strains in both liver pâté and BHI. Comparison of the three strains after incubation in the standard liver pâté and BHI showed that the relative transcription of prfA for O57 and the relative transcription of inlA and sigB for both O57 and 6896 were significantly higher when the strains were grown in BHI compared to the standard liver pâté. Reducing the NaCl content of the standard liver pâté did not change relative transcription levels of prfA, inlA, sigB or clpC (except for prfA in O57 and sigB in 6896). However, the presence of Ca-acetate and Ca-lactate induced relative transcription of the stress response gene, clpC, for all three strains. This study demonstrates that relative microbial gene transcription can be measured in complex food matrices and points to the need for designing experimental set-ups in real food matrices to replace the laboratory model systems. With respect to L. monocytogenes, it seems that the NaCl content of liver pâté can be lowered within the investigated range without significant changes in relative virulence gene transcription while more caution should be taken when adding organic acids such as acetate and lactate.
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Affiliation(s)
- Inger Olesen
- Department of Food Science, Faculty of Life Sciences, University of Copenhagen, Frederiksberg C, Denmark.
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Olesen I, Vogensen FK, Jespersen L. Gene transcription and virulence potential of Listeria monocytogenes strains after exposure to acidic and NaCl stress. Foodborne Pathog Dis 2009; 6:669-80. [PMID: 19580450 DOI: 10.1089/fpd.2008.0243] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Gene transcription and virulence potential of two strains of Listeria monocytogenes, EGD-e and 4140, were compared by quantitative real-time polymerase chain reaction and in a Caco-2 in vitro model after exposure to acidic (pH 5.5) and NaCl (4.5% w/v) stress. Strain-dependent differences in gene transcription were observed both after exposure to shock (six genes) and after long-term adaptation to stress (18 genes). In the shock experiments, a transient induction of clpC and clpE was seen for both strains, while transient induction of sigB, inlA, and inlB was observed for strain 4140 only; actA was only induced in EGD-e after NaCl shock. The long-term stress experiments were included to imitate the stress conditions encountered by L. monocytogenes when present in food products. Long-term adaptation of EGD-e to acidic stress induced transcription of iap and repressed flaA, while genes related to stress response and invasion (clpC, clpP, inlA, inlB, prfA, and sigB) were induced in 4140. Long-term adaptation of EGD-e to NaCl stress increased transcription of genes important for the intracellular life cycle (actA, hly, iap, inlA, inlB, plcA, plcB, and prfA), while few changes were observed for 4140. Experiments with Caco-2 confirmed that long-term adaptation of EGD-e and 4140 to acidic and NaCl stress is capable of increasing the virulence potential: an improved adhesion to Caco-2 was observed for both EGD-e and 4140 after acidic and NaCl stress, and increased invasion was seen for both strains after long-term NaCl stress. The fact that several virulence genes were up-regulated and that adhesion and invasion properties were increased demonstrate that certain environmental conditions in food products might influence the virulence potential of L. monocytogenes.
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Affiliation(s)
- Inger Olesen
- Department of Food Science, University of Copenhagen, Frederiksberg C, Denmark.
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89
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Andersen C, Jespersen L. Egalet® morphine, a once-a-day abuse resistant opioid analgesics: a double-blind, randomized, cross-over efficacy study in cancer patients. The Journal of Pain 2009. [DOI: 10.1016/j.jpain.2009.01.154] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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90
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Nielsen DS, Jacobsen T, Jespersen L, Koch AG, Arneborg N. Occurrence and growth of yeasts in processed meat products – Implications for potential spoilage. Meat Sci 2008; 80:919-26. [PMID: 22063618 DOI: 10.1016/j.meatsci.2008.04.011] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2007] [Revised: 03/06/2008] [Accepted: 04/11/2008] [Indexed: 11/26/2022]
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91
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Gori K, Mortensen HD, Arneborg N, Jespersen L. Ammonia production and its possible role as a mediator of communication for Debaryomyces hansenii and other cheese-relevant yeast species. J Dairy Sci 2008; 90:5032-41. [PMID: 17954742 DOI: 10.3168/jds.2006-750] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Ammonia production by yeasts may contribute to an increase in pH during the ripening of surface-ripened cheeses. The increase in pH has a stimulatory effect on the growth of secondary bacterial flora. Ammonia production of single colonies of Debaryomyces hansenii, Saccharomyces cerevisiae, Yarrowia lipolytica, and Geotrichum candidum was determined on glycerol medium (GM) agar and cheese agar. The ammonia production was found to vary, especially among yeast species, but also within strains of D. hansenii. In addition, variations in ammonia production were found between GM agar and cheese agar. Ammonia production was positively correlated to pH measured around colonies, which suggests ammonia production as an additional technological parameter for selection of secondary starter cultures for cheese ripening. Furthermore, ammonia appeared to act as a signaling molecule in D. hansenii as reported for other yeasts. On GM agar and cheese agar, D. hansenii showed ammonia production oriented toward neighboring colonies when colonies were grown close to other colonies of the same species; however, the time to oriented ammonia production differed among strains and media. In addition, an increase of ammonia production was determined for double colonies compared with single colonies of D. hansenii on GM agar. In general, similar levels of ammonia production were determined for both single and double colonies of D. hansenii on cheese agar.
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Affiliation(s)
- K Gori
- Department of Food Science, Food Microbiology, The Faculty of Life Sciences, University of Copenhagen, Rolighedsvej 30, DK-1958 Frederiksberg C, Denmark.
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92
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Mortensen HD, Dupont K, Jespersen L, Willats WGT, Arneborg N. Identification of amino acids involved in the Flo11p-mediated adhesion of Saccharomyces cerevisiae to a polystyrene surface using phage display with competitive elution. J Appl Microbiol 2008; 103:1041-7. [PMID: 17897208 DOI: 10.1111/j.1365-2672.2007.03325.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
AIMS To identify the main amino acids involved in the Flo11p-mediated adhesion of Saccharomyces cerevisiae to the polystyrene surface PolySorp. METHODS AND RESULTS Using a combination of phage display and competitive elution revealed that 12-mer peptides of phages from competitive panning with S. cerevisiae FLO11 wild-type (TBR1) cells had a higher consensus than those from competitive panning with S. cerevisiae flo11Delta mutant (TBR5) cells, suggesting that the wild-type cells interact with the plastic surface in a stronger and more similar way than the mutant cells. Tryptophan and proline were more abundant in the peptides of phages from competitive elution with FLO11 cells than in those from competitive elution with flo11Delta cells. Furthermore, two phages with hydrophobic peptides containing 1 or 2 tryptophan, and 3 or 5 proline, residues inhibited the adhesion of FLO11 cells to PolySorp more than a phage with a hydrophobic peptide containing no tryptophan and only two proline residues. CONCLUSIONS Our results suggest a key role of tryptophan and proline in the hydrophobic interactions between Flo11p on the S. cerevisiae cell surface and the PolySorp surface. SIGNIFICANCE AND IMPACT OF THE STUDY Our study may contribute to the development of novel strategies to limit yeast infections in hospitals and other medical environments.
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Affiliation(s)
- H D Mortensen
- Department of Food Science, The Royal Veterinary and Agricultural University, Frederiksberg C, Denmark
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93
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Klingberg TD, Lesnik U, Arneborg N, Raspor P, Jespersen L. Comparison of Saccharomyces cerevisiae strains of clinical and nonclinical origin by molecular typing and determination of putative virulence traits. FEMS Yeast Res 2008; 8:631-40. [PMID: 18355272 PMCID: PMC2430332 DOI: 10.1111/j.1567-1364.2008.00365.x] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Saccharomyces cerevisiae strains of clinical and nonclinical origin were compared by pulse field gel electrophoresis. Complete separation between strains of clinical origin and food strains by their chromosome length polymorphism was not obtained even though there was a tendency for the clinical and food strains to cluster separately. All the investigated strains, except for one food strain, were able to grow at temperatures > or =37 degrees C but not at 42 degrees C. Great strain variations were observed in pseudohyphal growth and invasiveness, but the characters were not linked to strains of clinical origin. The adhesion capacities of the yeast strains to a human intestinal epithelial cell line (Caco-2) in response to different nutritional availabilities were determined, as were the effects of the strains on the transepithelial electrical resistance (TER) across polarized monolayers of Caco-2 cells. The yeast strains displayed very low adhesion capacities to Caco-2 cells (0.6-6.2%), and no significant difference was observed between the strains of clinical and nonclinical origin. Both S. cerevisiae strains of clinical and non-clinical origin increased the TER of polarized monolayers of Caco-2 cells. Based on the results obtained in this study, no specific virulence factor was found that clearly separated the strains of clinical origin from the strains of nonclinical origin. On the contrary, all investigated strains of S. cerevisiae were found to strengthen the epithelial barrier function.
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94
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Vieira-Dalodé G, Jespersen L, Hounhouigan J, Moller PL, Nago CM, Jakobsen M. Lactic acid bacteria and yeasts associated with gowé production from sorghum in Bénin. J Appl Microbiol 2008; 103:342-9. [PMID: 17650194 DOI: 10.1111/j.1365-2672.2006.03252.x] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
AIMS To identify the dominant micro-organisms involved in the production of gowé, a fermented beverage, and to select the most appropriate species for starter culture development. METHODS AND RESULTS Samples of sorghum gowé produced twice at three different production sites were taken at different fermentation times. DNA amplification by internal transcribed spacer-polymerase chain reaction of 288 lactic acid bacteria (LAB) isolates and 16S rRNA gene sequencing of selected strains revealed that the dominant LAB responsible for gowé fermentation were Lactobacillus fermentum, Weissella confusa, Lactobacillus mucosae, Pediococcus acidilactici, Pediococcus pentosaceus and Weissella kimchii. DNA from 200 strains of yeasts was amplified and the D1/D2 domain of the 26S rRNA gene was sequenced for selected isolates, revealing that the yeasts species were Kluyveromyces marxianus, Pichia anomala, Candida krusei and Candida tropicalis. CONCLUSIONS Gowé processing is characterized by a mixed fermentation dominated by Lact. fermentum, W. confusa and Ped. acidilactici for the LAB and by K. marxianus, P. anomala and C. krusei for the yeasts. SIGNIFICANCE AND IMPACT OF THE STUDY The diversity of the LAB and yeasts identified offers new opportunities for technology upgrading and products development in gowé production. The identified species can be used as possible starter for a controlled fermentation of gowé.
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Affiliation(s)
- G Vieira-Dalodé
- Département de Nutrition et Sciences Alimentaires, Faculté des Sciences Agronomiques, Université d'Abomey-Calavi, Cotonou, Bénin
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95
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Schwan RF, Almeida EG, Souza-Dias MAG, Jespersen L. Yeast diversity in riceâcassava fermentations produced by the indigenous Tapirapé people of Brazil. FEMS Yeast Res 2007; 7:966-72. [PMID: 17697080 DOI: 10.1111/j.1567-1364.2007.00241.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
The Tapirapé people of the Tapi'itãwa tribe of Brazil produce several fermented foods and beverages, one of which is called 'cauim'. This beverage usually makes up the main staple food for adults and children. Several substrates are used in its production, including cassava, rice, corn, maize and peanuts. A fermentation using rice and cassava was conducted, and samples were collected at 4-h intervals for microbial analysis. The yeast population was low at the beginning of the fermentation and reached 6.9 x 10(7) CFU mL(-1) after 48 h. During the fermentation process common yeast species were identified by sequencing of the D1/D2 domain of the large-subunit (26S) rRNA gene. The predominant yeast species found was Candida tropicalis. Candida intermedia, Candida parapsilosis, Pichia guilliermondii, Saccharomyces cerevisiae and Trichosporon asahii were also found in high numbers during the fermentation. Exophiala dermatidis, often associated with blastomycosis, was found in the mass before inoculation and during the initial stages of the fermentation. Examination of these indigenous fermented foods may provide clues as to how food production and preservation can be expanded and thereby contribute to improve nutrition in native tribes in the region.
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Affiliation(s)
- Rosane F Schwan
- Biology Department, Federal University of Lavras, MG, Brazil.
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96
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Mortensen HD, Dupont K, Jespersen L, Arneborg N. The Flo11p-deficient Saccharomyces cerevisiae strain background S288c can adhere to plastic surfaces. Colloids Surf B Biointerfaces 2007; 60:131-4. [PMID: 17631987 DOI: 10.1016/j.colsurfb.2007.06.004] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2007] [Revised: 05/17/2007] [Accepted: 06/04/2007] [Indexed: 12/11/2022]
Abstract
The effects of four types of plastic surfaces and four pre-incubation media, containing high/low glucose and +/- amino acids, on adhesion of Saccharomyces cerevisiae BY4742 wild type and Deltaflo11 mutant (strain background S288c) were investigated. No difference in adhesive ability between the two yeast strains was observed in any of our experiments, thus confirming that FLO11 is not operational in the S. cerevisiae S288c strain background. The adhesive abilities of both yeast strains depended on the plastic type and pre-incubation conditions. The poorest adhesion was observed on hydrophilic polystyrene, whereas hydrophobic polystyrene resulted in moderate adhesion. The best adhesion of both yeast strains was observed on polystyrene surfaces with combined hydrophilic/hydrophobic domains. When amino acids were present in the pre-incubation media, lack of glucose increased the cell surface hydrophobicity and enhanced the adhesion to all four types of polystyrene. Lack of amino acids in the pre-incubation media increased the cell surface hydrophobicity and enhanced the adhesion especially to polystyrene surfaces with combined hydrophilic/hydrophobic domains. Our results suggest that glucose and amino acid starvation induces other genes than FLO11 in S. cerevisiae S288c coding for hydrophobic cell surface constituents with adhesive properties to especially moderately hydrophobic plastic surfaces.
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Affiliation(s)
- Henrik D Mortensen
- Department of Food Science, Faculty of Life Sciences, University of Copenhagen, Rolighedsvej 30, DK-1958 Frederiksberg C, Denmark
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97
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Abstract
The proteome of the highly NaCl-tolerant yeast Debaryomyces hansenii was investigated by two-dimensional polyacrylamide gel electrophoresis (2D PAGE), and 47 protein spots were identified by matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) followed by mass spectrometry (MS). The influence of NaCl on the D. hansenii proteome was investigated during the first 3 h of NaCl exposure. The rate of protein synthesis was strongly decreased by exposure to 8% and 12% (w/v) NaCl, as the average incorporation rates of l-[(35)S]methionine within the first 30 min after addition of NaCl were only 7% and 4% of the rate in medium without NaCl. In addition, the number of protein spots detected on 2D gels prepared from cells exposed to 8% and 12% (w/v) NaCl exceeded less than 28% of the number of protein spots detected on 2D gels prepared from cells without added NaCl. Several proteins were identified as being either induced or repressed upon NaCl exposure. The induced proteins were enzymes involved in glycerol synthesis/dissimilation and the upper part of glycolysis, whereas the repressed proteins were enzymes involved in the lower part of glycolysis, the route to the Krebs cycle, and the synthesis of amino acids. Furthermore, one heat shock protein (Ssa1p) was induced, whereas others (Ssb2p and Hsp60p) were repressed.
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Affiliation(s)
- Klaus Gori
- Department of Food Science, Food Microbiology, The Royal Veterinary and Agricultural University, Frederiksberg C, Denmark.
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98
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Mortensen HD, Gori K, Siegumfeldt H, Jespersen L, Arneborg N. Relationship between growth and pH gradients of individual cells of Debaryomyces hansenii as influenced by NaCl and solid substrate. Lett Appl Microbiol 2007; 44:279-85. [PMID: 17309505 DOI: 10.1111/j.1472-765x.2006.02067.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
AIMS To examine the relationship between the growth and pH gradients of Debaryomyces hansenii at a single-cell level. METHODS AND RESULTS Using bioimaging techniques, the cell areas and early pH gradients (Delta pH(10)), i.e. the pH gradients determined 10 min after initiation of experiments, were determined for single cells of two D. hansenii strains in fluid and on solid (agar) substrate with and without 8% (w/v) NaCl. The combination of NaCl and solid substrate prolonged the growth initiation of both D. hansenii strains additively. In all our experiments, primarily two groups of cells existed; a vital group consisting of growing single cells with intact early pH gradients, and a group of dead cells without early pH gradients. CONCLUSIONS Our results show that growth initiation of the D. hansenii cells is severely affected by NaCl and to a lesser extent by the type of substrate in an additive and strain dependent way. Moreover, the early pH gradient of a vital D. hansenii cell cannot be correlated with the rate of its subsequent growth. SIGNIFICANCE AND IMPACT OF THE STUDY Our study reveals new knowledge on the growth and pH gradients of D. hansenii on solid surfaces in the presence of NaCl.
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Affiliation(s)
- H D Mortensen
- Department of Food Science, Food Microbiology, The Royal Veterinary and Agricultural University, Frederiksberg C, Denmark
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Shetty PH, Hald B, Jespersen L. Surface binding of aflatoxin B1 by Saccharomyces cerevisiae strains with potential decontaminating abilities in indigenous fermented foods. Int J Food Microbiol 2007; 113:41-6. [PMID: 16996157 DOI: 10.1016/j.ijfoodmicro.2006.07.013] [Citation(s) in RCA: 116] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2005] [Revised: 06/19/2006] [Accepted: 07/04/2006] [Indexed: 10/24/2022]
Abstract
Saccharomyces cerevisiae constitutes one of the most important microorganisms involved in food fermentations throughout the world. Aflatoxin B(1) binding abilities of S. cerevisiae strains isolated from indigenous fermented foods from Ghana, West Africa were tested in vitro. Results show that aflatoxin binding was strain specific with 7 strains binding 10-20%, 8 strains binding 20-40% and 3 strains binding more than 40% of the added aflatoxin B(1) when grown and incubated under standard conditions. Binding by two of the strains was further characterized. Highest binding capacity was seen with cells collected at the exponential growth phase with the strains A18 and 26.1.11 binding 53.0 and 48.8% of the total toxin respectively and the binding reduced towards the stationary phase. Aflatoxin B(1) binding increased steadily when the cells were incubated with 1 to 20 microg/ml of aflatoxin B(1). Binding was not affected by the cells grown at temperatures ranging from 20 to 37 degrees C, but was significantly reduced at 15 degrees C. Binding seems to be a physical phenomenon with cells treated at 52, 55 and 60 degrees C for 5 and 10 min or 120 degrees C for 20 min binding significantly higher quantities (more than 2-fold in 120 degrees C treated cells) of aflatoxin B(1) than their viable counterpart. Similarly, when the cells were treated with 2 M HCl for 1 h, up to 2-fold increase in binding was observed. The results obtained show that some strains of S. cerevisiae, viable or non-viable, are effective aflatoxin binders and these properties should be considered in the selection of starter cultures for relevant indigenous fermented foods where high aflatoxin level is a potential health risk.
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Affiliation(s)
- Prathapkumar Halady Shetty
- Food Microbiology, Department of Food Science (IFV), The Royal Veterinary and Agricultural University (KVL), Rolighedsvej 30, DK-1958 Frederiksberg C, Denmark
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Ouoba LII, Diawara B, Jespersen L, Jakobsen M. Antimicrobial activity of Bacillus subtilis and Bacillus pumilus during the fermentation of African locust bean (Parkia biglobosa) for Soumbala production. J Appl Microbiol 2006; 102:963-70. [PMID: 17381739 DOI: 10.1111/j.1365-2672.2006.03156.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
AIMS To examine predominant isolates of Bacillus subtilis and B. pumilus isolated from Soumbala for their antimicrobial activity against indicator microorganisms as Micrococcus luteus, Staphyloccocus aureus, Bacillus cereus, Enterococus facium, Listeria monocytogenes, Escherichia coli, Salmonella typhimurium, Shigella dysenteriae, Yersinia enterocolitica, Aspergillus ochraceus and Penicillium roqueforti. METHODS AND RESULTS Growth inhibition of indicator microorganisms by cells and supernatants of three B. subtilis and two B. pumilus strains was investigated using agar diffusion tests. Inactivation of indicator microorganisms was investigated in laboratory broth and during the fermentation of African locust bean for Soumbala production. The Bacillus isolates showed variable ability of inhibition and inactivation according to the indicator microorganism. The supernatants of pure cultures of B. subtilis inhibited one strain of B. cereus, one of Staph. aureus and E. coli and caused abnormal germination of Aspergillus ochraceus. The supernatant of mixed cultures of B. subtilis and indicators inhibited all the indicators. A treatment with protease eliminated the inhibitions. Isolates of B. subtilis inactivated all the indicators organisms during the fermentation of African locust bean as well as in laboratory broth with about five to eight decimal reduction. CONCLUSION Bacillus isolates from Soumbala inhibit and inactivate Gram-positive and Gram-negative bacteria as well as ochratoxin A producing fungi during both laboratory cultivation and natural fermentation. SIGNIFICANCE AND IMPACT OF THE STUDY Selection of starter cultures of Bacillus spp. for controlled production of Soumbala.
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Affiliation(s)
- L I I Ouoba
- Department of Food Science, Food Microbiology, Royal Veterinary and Agricultural University, Copenhagen, Denmark.
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