Auli Haikara

VTT Technical Research Centre of Finland, Esbo, Uusimaa, Finland

Are you Auli Haikara?

Claim your profile

Publications (28)52.37 Total impact

  • Source
    Riikka Juvonen · Auli Haikara
    [Show abstract] [Hide abstract]
    ABSTRACT: Journal of the Institute of Brewing Vol.115 Nr.3, 167 - 176 The aim of this study was to evaluate easy pre-PCR processing procedures to allow rapid and reliable detection of strictly anaerobic beer-spoilage bacteria throughout the brewing process by end-point and real-time PCR techniques. The efficiencies of the new procedures were evaluated using spiked brewery samples and specific PCRs for the target group bacteria. We found for the first time that the inclusion of 0.25% (w/v) bovine serum albumin (BSA) or 0.5% (w/v) polyvinyl pyrrolidone (PVP) in the end-point PCR mixture reduces the inhibiting effect of brewery sample extracts (3-10%, v/v) on PCR. Membrane filtration with a PVP or a sodium tri-polyphosphate-EDTA wash, and cross-flow filtration were the most promising new methods to reduce inhibitors from beer samples before cell lysis. Together with BSA, they allowed the analysis of 10% (v/v) of crude extracts instead of <3% (v/v). Moreover, we developed a one-hour procedure to prepare target DNA from process samples containing brewer's yeast. It involved removal of inhibitors by a twostep centrifugation followed by physical disruption of cells. The detection limit of the procedure was 101-103 CFU/mL. The developed procedures help to reduce the risk of partial or complete PCR failure due to inhibition and target DNA losses, with minimal sample handling.
    Full-text · Article · Jan 2009
  • Riikka Juvonen · Teija Koivula · Auli Haikara
    [Show abstract] [Hide abstract]
    ABSTRACT: The strictly anaerobic brewery contaminants of the genera Pectinatus, Megasphaera, Selenomonas and Zymophilus in the class Clostridia constitute an important group of spoilage bacteria of unpasteurised, packaged beers. The aim of this study was to develop and evaluate group-specific PCR methods to detect and differentiate these bacteria in beer. A group-specific primer pair targeting a 342-bp variable region of the 16S rRNA gene was designed and evaluated in end-point PCR with gel electrophoresis and in real-time PCR with SYBR Green I dye. Significant cross-reactions with DNAs from any of the forty-two brewery-related, non-target microbes or from real brewery samples were not detected in either PCR system. The group-specific end-point and real-time PCR products could be differentiated according to species/genus and spoilage potential using restriction fragment length polymorphism (KpnI, XmnI, BssHII, ScaI) and melting point curve analysis, respectively. In combination with a rapid DNA extraction method, the PCR reactions detected ca 10(0)-10(3) CFU per 25 ml of beer depending on the strain and on the PCR system. The end-point and real-time PCR analysis took 6-7 h and 2-3 h, respectively. Pre-PCR enrichment of beer samples for 1-3 days ensured the detection of even a single cultivable cell. The PCR and cultivation results of real brewery samples were mostly congruent but the PCR methods were occasionally more sensitive. The PCR methods developed allow the detection of all the nine beer-spoilage Pectinatus, Megasphaera, Selenomonas and Zymophilus species in a single reaction and their differentiation below group level and reduce the analysis time for testing of their presence in beer samples by 1-2 days. The methods can be applied for brewery routine quality control and for studying occurrence, diversity and numbers of the strictly anaerobic beer spoilers in the brewing process.
    No preview · Article · Aug 2008 · International Journal of Food Microbiology
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The efficiency of a novel strain of lactic acid bacteria inoculant (Lactobacillus plantarum VTT E-78076, E76) on the fermentation quality of wilted silage was studied. Furthermore, the possibility to improve aero-bic stability of silages by combining an inoculant and chemical preservatives was investigated. Two ex-periments were conducted with wilted timothy-meadow fescue herbage (dry matter 429 and 344 g kg -1) using six treatments. In experiment I, E76 (10 6 cfu g -1 fresh matter (FM)) was applied alone and in combina-tion with sodium benzoate (0.3 g kg -1 grass FM) or low rate of formic acid (0.4 l t -1 FM). In experiment II, E76 and a commercial inoculant were applied alone and in combination with sodium benzoate. Untreated silage and formic acid (4 l t -1 FM) treated silage served as negative and positive controls in both experi-ments. The effect of sodium benzoate and potassium sorbate in experiment I, on aerobic stability was tested by treating silages prior to aerobic stability measurements. The novel lactic acid bacteria inoculant was equally effective in improving fermentation quality as the commercial inoculant. However, the aerobic stability of both inoculated silages was poorer than that of formic acid treated or the untreated one in one of the experiments. The results suggested that antimicrobial properties of E76 were not effective enough to improve aerobic instability. One option to overcome this problem is to use chemical additives in combina-tion with the inoculants.
    Full-text · Article · Sep 2006 · Agricultural and Food Science
  • Erna Storgårds · Auli Haikara · Riikka Juvonen

    No preview · Chapter · Aug 2006
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Lactobacillus plantarum VTT E-78076 (E76) and Pediococcus pentosaceus VTT E-90390 (E390) starter cultures were added to the steeping water of normal malting barley in order to balance the microbial community and to enhance malt processability. In this study, we also investigated the effects of lactic acid-acidified MRS-spent medium (MRS-LA) on malting performance. Malting trials with five different two-row barley varieties were carried out in 25 kg pilot scale. The starter cultures promoted yeast growth during malting and restricted the growth of harmful bacteria and Fusarium fungi. Furthermore, they had positive effects on malt characteristics. Reduction in wort viscosity and beta-glucan content and enhanced xylanase and microbial beta-glucanase activities were observed. Starter cultures notably improved lautering performance. Some of the beneficial effects were due to the lactic acid and low pH, as similar effects were obtained with MRS-LA. Starter cultures offer a tool for tailoring of malt properties.
    Full-text · Article · Jun 2006 · Journal of Agricultural and Food Chemistry

  • No preview · Article · Mar 2006 · FEMS Microbiology Letters
  • Source
    T T Koivula · R Juvonen · A Haikara · M-L Suihko
    [Show abstract] [Hide abstract]
    ABSTRACT: To study the ability of automated ribotyping to characterize Obesumbacterium proteus and Hafnia alvei, to design primers and to evaluate standard end-point and real-time PCR for the detection of O. proteus biotype 1 in beer and in brewers's yeast-containing samples. Automated ribotyping was carried out using the standard method with EcoRI and PvuII. The digestions with both enzymes clearly differentiated O. proteus biotypes 1 and 2 and H. alvei. PCR primers were designed according to the 16S rRNA gene sequence of the O. proteus type strain. Two primer sets (Obs137-Obs558 and Obs137-Obs617) detected O. proteus biotype 1 and H. alvei but not O. proteus biotype 2 or other tested beer spoilage bacteria (40 species) in the end-point and real-time PCR, indicating their high specificity. The detection limit for O. proteus was 160-1600 CFU 100 ml(-1) beer in the end-point PCR reactions and < or =160 CFU 100 ml(-1) beer in the real-time PCR reactions. More cells (from 16 to 3200) were needed for detection in the presence of brewer's yeast cells. Automated ribotyping is a useful tool to characterize and identify O. proteus and H. alvei isolates. The designed primers are suitable for the rapid detection of O. proteus biotype 1 and H. alvei in brewery samples by PCR. Automated ribotyping and PCR could improve microbiological quality control in breweries by facilitating the detection, identification and tracing of spoilage bacteria.
    Full-text · Article · Feb 2006 · Journal of Applied Microbiology
  • Source

    Full-text · Article · Feb 2006 · Advances in Experimental Medicine and Biology
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: A real-time PCR technique was applied for the quantification of trichothecene-producing Fusarium species (TMTRI assay) as well as the highly toxigenic Fusarium graminearum (TMFg12 assay) present in barley grain and malt. PCR results were compared to the amounts of trichothecenes detected in the samples to find out if the PCR assays can be used for trichothecene screening instead of expensive and laborious chemical analyses. DNA was extracted from ground kernels using a commercial DNA extraction kit and analysed in a LightCycler® system using specific primers and fluorogenic TaqMan probes. Both naturally and artificially contaminated grains were analysed. The TMTRI assay and the TMFg12 assay enabled the quantification of trichothecene-producing Fusarium DNA and F. graminearum DNA present in barley grain and malt samples, respectively. Both TaqMan assays were considered to be sensitive and reproducible. Linearity of the assays was 4–5 log units when pure Fusarium DNAs were tested. The amount of Fusarium DNA analysed with the TMTRI-trichothecene assay could be used for estimation of the deoxynivalenol (DON) content in barley grain. Furthermore, the TMFg12 assay for F. graminearum gave a good estimation of the DON content in north American barley and malt samples, whilst the correlation was poor among Finnish samples. DON content and the level of F. graminearum DNA were found to be naturally low in Finnish barleys.
    Full-text · Article · Jan 2006 · European Journal of Plant Pathology
  • Auli Haikara · Ilkka Helander

    No preview · Chapter · Dec 2005
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Bacteria of the genus Pectinatus emerged during the seventies as contaminants and spoilage organisms in packaged beer. This genus comprises two species, Pectinatus cerevisiiphilus and Pectinatus frisingensis; both are strict anaerobes. On the basis of genomic properties the genus is placed among low GC Gram-positive bacteria (phylum Firmicutes, class Clostridia, order Clostridiales, family Acidaminococcaceae). Despite this assignment, Pectinatus bacteria possess an outer membrane and lipopolysaccharide (LPS) typical of Gram-negative bacteria. The present review compiles the structural and compositional studies performed on Pectinatus LPS. These lipopolysaccharides exhibit extensive heterogeneity, i.e. several macromolecularly and structurally distinct LPS molecules are produced by each strain. Whereas heterogeneity is a common property in lipopolysaccharides, Pectinatus LPS have been shown to contain exceptional carbohydrate structures, consisting of a fairly conserved core region that carries a large non-repetitive saccharide that probably replaces the O-specific chain. Such structures represent a novel architectural principle of the LPS molecule.
    Full-text · Article · Nov 2004 · FEMS Microbiology Reviews
  • Liisa Nohynek · Eija Saski · Auli Haikara · Laura Raaska
    [Show abstract] [Hide abstract]
    ABSTRACT: Rapid fluorescence techniques were evaluated for the detection of bacterial contaminants in papermaking chemicals including starch and the resin-based sizes and starch slurries used in the paper industry. Viable and non-viable bacterial cells were visualised by fluorescent probes and detected by epifluorescence microscopy and flow cytometry. The best discrimination ability was obtained with the fluorescent probes LIVE/DEAD and SYBR Green, based on the staining of cellular nucleic acid, and ChemChrome V3, which demonstrated cellular enzymatic activity. The process samples had to be diluted and filtered before fluorescence staining and analysis because they were viscous and contained solid particles. Fluorescence microscopic counts of bacteria in highly contaminated process samples were similar to plate counts, but flow cytometric enumeration of bacterial cells in process samples yielded 2- to 10-fold lower counts compared with plate counts, depending on the consistency of the sample. The detection limits in flow cytometric analysis and in epifluorescence microscopy were 10(3)-10(6) cells ml(-1) and 10(5)-10(6) cells ml(-1), respectively. Intrinsic bacterial contamination was detectable with fluorescence techniques and highly contaminated process samples could be analysed with fluorescence methods.
    No preview · Article · May 2003 · Journal of Industrial Microbiology and Biotechnology
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Barley (Hordeum vulgare L.) that is infested with Fusarium head blight (FHB, ‘scab’) is unsuitable for malting and brewing because it may contain mycotoxins and has unacceptable malting quality. Fungal proteinases are apparently often involved in plant-microbe interactions, where they degrade storage proteins, but very little is known about the enzymes that the fungi produce in the infected grain. We have shown previously that one plant pathogenic fungus, Fusarium culmorum, produced subtilisin- and trypsin-like enzymes when grown in a cereal protein medium. To establish whether these proteinases were also synthesized in FHB-infested barley in vivo, field-grown barley was infested as the heads emerged. Extracts were prepared from the grain as it developed and matured and their proteolytic activities were measured with N-succinyl-Ala-Ala-Pro-Phe p -nitroanilide and N-benzoyl-Val-Gly-Arg p -nitroanilide. The heavily infested barleys contained both subtilisin- and trypsin-like activities. These enzymes reacted with antibodies prepared against each of the two F. culmorum proteinases, indicating that those produced in the laboratory cultures and in the field-infested barley were the same. The presence of these proteinases correlated with the degradation of specific buffer-soluble proteins in the infested grains. These enzymes readily hydrolyzed barley grain storage proteins (C- and D-hordeins) in vitro. The presence of these Fusarium proteinases in the barley indicates that they probably play an important role in the infestation, but exactly how and when they function is not clear.
    Full-text · Article · May 2003 · Journal of Cereal Science
  • Source

    Full-text · Book · Jan 2001
  • Source
    Maija‐Liisa Suihko · Auli Haikara
    [Show abstract] [Hide abstract]
    ABSTRACT: A total of 32 Pectinatus and Megasphaera strains, isolated from spoiled beer or brewery environments and identified by conventional methods, were analysed by the automated RiboPrinter® System. One strain from each ribotype was further subjected to partial 16S rDNA sequencing to confirm the ribotyping results. The restriction enzyme EcoRI was used in ribotyping of Pectinatus strains. Eight strains, identified by conventional tests as P. cerevisiiphilus, generated five different ribotypes. The strains of three types were considered to be members of P. cerevisiiphilus, but the strains of two types were most probably members of a new species within the genus Pectinatus. The 24 strains identified by conventional tests as P. frisingenis generated nine different ribotypes. The similarity between the ribotypes was rather low, but all these strains obviously belonged to the same species. Thirteen Megasphaera cerevisiae strains were analysed with three restriction enzymes EcoRI, Pstl and PvuII and four, six and three different ribotypes, respectively, were generated resulting in seven different combinations. The best discrimination among these strains was obtained with Pstl. According to these results 12 of 13 brewery strains were considered to be M. cerevisiae, but one strain most probably represented a new species within the genus Megasphaera. During the work, 14 RiboPrint® patterns of Pectinatus, five of Megasphaera, two of Selenomonas and two of Zymophilus were created with EcoRI. In addition seven patterns of Megasphaera were created with Pstl and four with Pvull. All these identification patterns (genetic fingerprints) were saved at the database of VTT for future use.
    Preview · Article · Jan 2001
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Yeast are usually known for their beneficial role in the production of fermented foods. However, yeast can also act as food spoilage agents. Abundant growth of unwanted yeasts during various stages of production can lead to production problems and quality defects in the final product. Hence, the production of microbiologically wholesome food is usually best achieved by controlling microbial contaminations throughout the whole production chain. This literature review is an extensive information package about foodborne yeasts and their control and identification methods. First, general properties and the classification system of yeasts are summarised alongside with the occurrence and effects of yeast in various types of food. The review focuses on the presentation of different factors controlling the contamination and growth of yeasts in food. Good production hygiene has a key role in the prevention of contaminations. The few published articles about the biofilms formed by foodborne yeasts and about the effects of different cleaning and disinfecting agents on yeasts are summarised, and the latest information about the effects of different physical, chemical and biological factors on yeasts is presented. Traditional and state-of-the-art food preservation methods and their effectiveness against yeast are summarised. Traditional methods, such as chemical preservatives, are often ineffective against food spoilage strains and there is a tendency to avoid their use. Recently, promising results have been obtained with the combined use of different minimal processing methods. However, much research work is still needed in this field. The solving of contamination problems and the selection of appropriate intervention measures often necessitates rapid tracing and identification of the contaminating organisms. In this publication, phenotypic and genotypic methods for the identification, typing and detection of foodborne yeasts are reviewed in detail and their practicality in routine food control is discussed.
    Full-text · Article · Jan 2001 · VTT Tiedotteita - Valtion Teknillinen Tutkimuskeskus
  • [Show abstract] [Hide abstract]
    ABSTRACT: Anaerobic bacteria of the genera Megasphaera and Pectinatus cause beer spoilage by producing off flavours and turbidity. Detection of these organisms is complicated by the strict anaerobic conditions and lengthy incubation times required for their cultivation, consequently there is a need for more rapid detection methods. A polymerase chain reaction (PCR) method and a colorimetric microplate hybridization assay were developed for the rapid and specific detection of Megasphaera cerevisiae and Pectinatus spp. A biotinylated primer pair was designed for the amplification of a 403 base pair (bp) fragment of the M. cerevisiae 16S rRNA gene and a primer pair from literature was used for the amplification of an 816 bp fragment of Pectinatus 16S rRNA gene. Amplified PCR products were analyzed by the colorimetric microplate hybridization method in which a biotinylated PCR product was captured by streptavidin and hybridized with a digoxigenin-labelled oligonucleotide probe. In the final step an enzyme-linked antibody and a colorimetric reaction were utilized. A simple and rapid sample treatment was set up for the PCR detection of contaminants in beer. Detection of M. cerevisiae (≥5·103 colony forming units [cfu]/100 ml) and Pectinatus frisingensis (≥5·105 cfu/100 ml) in beer was successful, but the sensitivity of the assay still needs to be improved for direct detection of the small amounts of bacteria present in beer.
    No preview · Article · Jan 1999 · International Journal of Food Microbiology
  • R. Juvonen · R. Satokari · K. Mallison · A. Haikara
    [Show abstract] [Hide abstract]
    ABSTRACT: Cultivation methods for the detection of bacteria in beer, although simple and sensitive, are time-consuming and lack specificity. In this study, the sensitivity of a polymerase chain reaction (PCR) assay consisting of an easy sample treatment and specific primers for Lactobacillus lindneri, L. brevis, Megasphaera cerevisiae, and Pectinatus spp. was improved by pre-enrichment. A pre-enrichment broth supporting the growth of lactobacilli and anaerobic beer spoilers better than currently used media was formulated. For determination of the pre-enrichment times needed for PCR detection of these contaminants, artificially contaminated beer samples were mixed with the pre-enrichment broth and incubated anaerobically at 30°C. Low levels of lactobacilli (≤10 CFU/100 ml) were detected after 1-3 days, Pectinatus spp. after 2-4 days, and M. cerevisiae after 2-3 days of pre-enrichment, depending on the strain and the alcohol content of the beer. After the pre-enrichment, the PCR analysis took <8 hr. The time saving compared to corresponding conventional methods requiring up to several weeks is marked, especially for L. lindneri, M. cerevisiae, and Pectinatus spp. Moreover, the assay described allows species- or genus-level detection of the most harmful beer spoilage bacteria in finished beer and is sensitive and simple enough for routine work.
    No preview · Article · Jan 1999 · Journal of the American Society of Brewing Chemists
  • Matti Linko · Auli Haikara · Anneli Ritala · Merja Penttilä
    [Show abstract] [Hide abstract]
    ABSTRACT: Brewing is often mentioned as a typical example of traditional or old biotechnology, because of its extremely long history. However, the modern malting and brewing industry applies a whole spectrum of new technical, biochemical, microbiological and genetic inventions. Examples of contemporary achievements can be found along the whole production chain from barley to beer. Malted barley contains all the enzymes needed for all-malt brews. Exogenous microbial enzymes may be needed when using high amounts of cereal adjuncts. Transgenic barleys and proper starter cultures in malting offer interesting new possibilities to ensure balanced enzyme activities and to avoid harmful Fusarium contaminations. High gravity brewing, automated mash filters and hop extracts produced with super-critical or liquid carbon dioxide have been adopted by the industry. Continuous bioreactors with immobilized yeast are already used for maturation of beer. The residence time in the bioreactor is only 2 h, whereas several weeks are needed for traditional lagering. Continuous main fermentation with immobilized yeast is the next step. Several genetically modified brewer's yeasts have been constructed, e.g. yeasts encoding α-acetolactate decarboxylase and super-flocculating yeasts. The brewing industry is now waiting to be assured of consumer approval.
    No preview · Article · Oct 1998
  • Matti Linko · Auli Haikara · Anneli Ritala · Merja Penttilä
    [Show abstract] [Hide abstract]
    ABSTRACT: Brewing is often mentioned as a typical example of traditional or old biotechnology, because of its extremely long history. However, the modern malting and brewing industry applies a whole spectrum of new technical, biochemical, microbiological and genetic inventions. Examples of contemporary achievements can be found along the whole production chain from barley to beer. Malted barley contains all the enzymes needed for all-malt brews. Exogenous microbial enzymes may be needed when using high amounts of cereal adjuncts. Transgenic barleys and proper starter cultures in malting offer interesting new possibilities to ensure balanced enzyme activities and to avoid harmful Fusarium contaminations. High gravity brewing, automated mash filters and hop extracts produced with super-critical or liquid carbon dioxide have been adopted by the industry. Continuous bioreactors with immobilized yeast are already used for maturation of beer. The residence time in the bioreactor is only 2 h, whereas several weeks are needed for traditional lagering. Continuous main fermentation with immobilized yeast is the next step. Several genetically modified brewer's yeasts have been constructed, e.g. yeasts encoding α-acetolactate decarboxylase and super-flocculating yeasts. The brewing industry is now waiting to be assured of consumer approval.
    No preview · Article · Oct 1998 · Journal of Biotechnology

Publication Stats

484 Citations
52.37 Total Impact Points

Institutions

  • 1983-2009
    • VTT Technical Research Centre of Finland
      Esbo, Uusimaa, Finland
  • 2006
    • MTT Agrifood Research
      • Animal Production Research Unit
      Jockis, Southern Finland Province, Finland
  • 1999
    • University of the West of England, Bristol
      Bristol, England, United Kingdom