References of "Journal of Applied Microbiology"
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See detailDevelopment and validation of stable reference materials for food microbiology using Bacillus cereus and Clostridium perfringens spores
Abdelmassih, Marleen; Planchon, Viviane; Anceau, Christine ULg et al

in Journal of Applied Microbiology (2011)

To develop a new type of microbiological Reference Materials (RMs), displaying long-term stability at room temperature. The purpose was to produce and validate two batches of RMs for the enumeration of ... [more ▼]

To develop a new type of microbiological Reference Materials (RMs), displaying long-term stability at room temperature. The purpose was to produce and validate two batches of RMs for the enumeration of Bacillus cereus and Clostridium perfringens. Methods and Results: The RMs were based on spores of B. cereus and Cl. perfringens, adsorbed on calcium carbonate pellets. Two batches of 1000 units were manufactured and validated in compliance with ISO guide 35. After verification of their homogeneity, the stability of the ‘RM-B. cereus’ and ‘RMCl. perfringens’ batches was proven during at least 36 and 9 months, respectively, at room temperature. The validation study was completed by international collaborative trial involving 12 laboratories, allowing the validation of the assigned values. Conclusions: The methodology developed in this work enabled to produce easy-to-handle and cost-effective RMs, displaying an unprecedented stability at room temperature, a good homogeneity and a precise and validated assigned value. Significance and Impact of the Study: This study revealed new paths for the development of stable microbiological RMs. Overcoming the intrinsic instability of the living cells makes it possible to produce valuable tools for the quality assurance of microbiology laboratories. Jou [less ▲]

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See detailEffect of temperature and water activity on spore germination and mycelial growth of three fungal biocontrol agents against water hyacinth (Eichhornia crassipes)
Dagno, Karim ULg; Lahlali, Rachid; Diourté, M. et al

in Journal of Applied Microbiology (2011), 110

The fungi were grown in vitro on plates containing potato dextrose agar medium at different aw values (glycerol being added to adjust the aw). The percentage of viable conidia and radial growth rate ... [more ▼]

The fungi were grown in vitro on plates containing potato dextrose agar medium at different aw values (glycerol being added to adjust the aw). The percentage of viable conidia and radial growth rate decreased with decreasing water activity. Statistical analysis showed a significant effect of aw, temperature and the aw temperature interaction on mycelial growth (P < 0Æ0001). Water activity emerged as the factor exerting the greatest influence. Differences were observed between the fungi tested, the C. malorum appearing more tolerant to low aw and the F. sacchari more tolerant to high temperature (35 C). Growth models predicting the combined effect of aw and temperature were developed and response surfaces generated, showing fairly good agreement with the experimental values. Conclusions: Our results confirm the previous finding that aw has a greater influence than temperature on fungal growth. Under most conditions, variation of environmental factors has a detrimental influence on the percentage of viable conidia and mycelial growth rate of fungal isolates. [less ▲]

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See detailTyping of O26 enterohaemorrhagic and enteropathogenic Escherichia coli isolated from humans and cattle with IS621 multiplex PCR-based fingerprinting.
Mainil, Jacques ULg; Bardiau, Marjorie ULg; Ooka, T. et al

in Journal of Applied Microbiology (2011), 111(3), 773-86

AIMS: This study evaluated a typing method of O26:H11 enterohaemorrhagic and enteropathogenic Escherichia coli (EHEC and EPEC) based on the variation in genomic location and copy numbers of IS621. METHODS ... [more ▼]

AIMS: This study evaluated a typing method of O26:H11 enterohaemorrhagic and enteropathogenic Escherichia coli (EHEC and EPEC) based on the variation in genomic location and copy numbers of IS621. METHODS AND RESULTS: Two multiplex PCRs, targeting either the left (5') or right (3') IS/chromosome junction of 12 IS621 insertion sites and one PCR specific of another truncated copy, were developed. Thirty-eight amplification profiles were observed amongst a collection of 69 human and bovine O26:H11 EHEC and EPEC. Seventy-one per cent of the 45 EHEC and EPEC with identical IS621 fingerprints within groups of two, three or four isolates had >85% pulsed field gel electrophoresis (PFGE) profile similarity, including four groups of epidemiologically related EHEC or EPEC, while most of the groups had <85% similarity between each others. Epidemiologically related EHEC from each of three independent outbreaks in Japan and Belgium also exhibited identical IS621 fingerprints and PFGE profiles. CONCLUSIONS: The IS621 fingerprinting and the PFGE are complementary typing assays of EHEC and EPEC; though, the former is less discriminatory. SIGNIFICANCE AND IMPACT OF THE STUDY: The IS621 printing method represents a rapid (24 h) first-line surveillance and typing assay, to compare and trace back O26:H11 EHEC and EPEC during surveys in farms, multiple human cases and outbreaks. [less ▲]

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See detailEnteropathogenic (EPEC), enterohaemorragic (EHEC) and verotoxigenic (VTEC) Escherichia coli in wild cervids
Bardiau, Marjorie ULg; Grégoire, Fabien ULg; Muylaert, Adeline ULg et al

in Journal of Applied Microbiology (2010), 109(6), 2214-2222

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See detailBiological control of grey mould in strawberry fruits by halophilic bacteria
Essghaier, Badiaa; Fardeau, ML; Cayol, JL et al

in Journal of Applied Microbiology (2009), 106(3), 833-846

Aims: Grey mould caused by Botrytis cinerea is an economically important disease of strawberries in Tunisia and worldwide. The aim of this study was to select effective halophilic bacteria from ... [more ▼]

Aims: Grey mould caused by Botrytis cinerea is an economically important disease of strawberries in Tunisia and worldwide. The aim of this study was to select effective halophilic bacteria from hypersaline ecosystems and evaluate the abilities of antifungal bacteria to secrete extracellular hydrolytic enzymes, anti- Botrytis metabolites and volatiles. Methods and Results: Grey mould was reduced in strawberry fruits treated with halophilic antagonists and artificially inoculated with B. cinerea. Thirty strains (20Æ2%) were active against the pathogen and reduced the percentage of fruits infected after 3 days of storage at 20 C, from 50% to 91Æ66%. The antagonists were characterized by phenotypic tests and 16S rDNA sequencing. They were identified as belonging to one of the species: Virgibacillus marismortui, B. subtilis, B. pumilus, B. licheniformis, Terribacillus halophilus, Halomonas elongata, Planococcus rifietoensis, Staphylococcus equorum and Staphylococcus sp. The effective isolates were tested for antifungal secondary metabolites. Conclusions: Moderately halophilic bacteria may be useful in biological control against this pathogen during postharvest storage of strawberries. Significance and Impact of the study: The use of such bacteria may constitute an important alternative to synthetic fungicides. These moderate halophiles can be exploited in commercial production and application of the effective strains under storage and greenhouse conditions. [less ▲]

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See detailCyanobacteria from benthic mats of Antarctic lakes as a source of new bioactivities
Biondi, Natascia; Tredici, Mario; Taton, Arnaud et al

in Journal of Applied Microbiology (2008), 105(1), 105-115

Aims: To exploit the cyanobacterial diversity of microbial mats growing in the benthic environment of Antarctic lakes for the discovery of novel antibiotic and antitumour activities. Methods and results ... [more ▼]

Aims: To exploit the cyanobacterial diversity of microbial mats growing in the benthic environment of Antarctic lakes for the discovery of novel antibiotic and antitumour activities. Methods and results: In all, 51 Antarctic cyanobacteria isolated from benthic mats were cultivated in the laboratory by optimizing temperature, irradiance and mixing. Productivity was generally very low (£60 mg l)1 d)1) with growth rates (l) in the range of 0Æ02–0Æ44 d)1. Growth rates were limited by photosensitivity, sensitivity to air bubbling, polysaccharide production or cell aggregation. Despite this, 126 extracts were prepared from 48 strains and screened for antimicrobial and cytotoxic activities. Seventeen cyanobacteria showed antimicrobial activity (against the Gram-positive Staphylococcus aureus, the filamentous fungus Aspergillus fumigatus or the yeast Cryptococcus neoformans), and 25 were cytotoxic. The bioactivities were not in accordance with the phylogenetic grouping, but rather strain-specific. One active strain was cultivated in a 10-l photobioreactor. Conclusions: Isolation and mass cultivation of Antarctic cyanobacteria and LCMS (liquid chromatography ⁄ mass spectrometry) fractionation of extracts from a subset of those strains (hits) that exhibited relatively potent antibacterial and ⁄ or antifungal activities, evidenced a chemical novelty worthy of further investigation. Significance and impact of the study: Development of isolation, cultivation and screening methods for Antarctic cyanobacteria has led to the discovery of strains endowed with interesting antimicrobial and antitumour activities. [less ▲]

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See detailBifidobacteria as indicators of faecal contamination along a sheep meat production chain
Delcenserie, Véronique ULg; Loncaric, D.; Bonaparte, Christine et al

in Journal of Applied Microbiology (2008), 104(1), 276-284

Aims: The potential use of bifidobacteria as indicators for faecal contamination was studied along a sheep meat production and processing chain. The levels of bifidobacteria were compared with those of ... [more ▼]

Aims: The potential use of bifidobacteria as indicators for faecal contamination was studied along a sheep meat production and processing chain. The levels of bifidobacteria were compared with those of Escherichia coli. Total viable counts were followed along the chain (244 samples). Methods and Results: Forty-three per cent of the samples contained bifidobacteria, of which 15% were solely detected using a PCR method based on the hsp60 gene and not by a culture-based method. Bifidobacteria were detected in only three of nine sheep faeces samples using one or the other method. However, carcasses (types C and E) were highly contaminated. These sample types (30% and 28%, respectively) were positive for bifidobacteria and negative for E. coli. The species Bifidobacterium pseudolongum and Bif. thermophilum, isolated from faecal samples, were predominant. Bifidobacterium choerinum were found in C, D, E and F sample types. Conclusions: Bifidobacteria were shown more efficient than E. coli in carcasses samples. The presence of Bif. choerinum suggested a faecal pork contamination. Significance and Impact of the Study: Detection and identification of bifidobacteria, in correlation with E. coli counting, should improve hygiene quality of mutton processing chains. [less ▲]

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See detailResponse Surface Methodology Study Of The Combined Effects Of Temperature, Ph, And A(W) On The Growth Rate Of Trichoderma Asperellum
Begoude, Bad.; Lahlali, R.; Friel, D. et al

in Journal of Applied Microbiology (2007), 103(4), 845-854

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See detailIn Vitro Effects Of Water Activity, Temperature And Solutes On The Growth Rate Of P-Italicum Wehmer And P-Digitatum Sacc.
Lahlali, R.; Serrhini, Mn.; Friel, D. et al

in Journal of Applied Microbiology (2006), 101(3), 628-636

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See detailPrevalence of enterohaemorrhagic Escherichia coli from serotype O157 and other attaching and effacing Escherichia coli on bovine carcasses in Algeria
Chahed, Amina; China, Bernard; Mainil, Jacques ULg et al

in Journal of Applied Microbiology (2006), 101(2), 361-368

AIMS: Bovine meat is the principal source of human contamination of attaching and effacing Escherichia coli, including enterohaemorrhagic E. coli O157. The aim was to study the prevalence of these strains ... [more ▼]

AIMS: Bovine meat is the principal source of human contamination of attaching and effacing Escherichia coli, including enterohaemorrhagic E. coli O157. The aim was to study the prevalence of these strains on bovine carcasses in Algeria. METHODS AND RESULTS: Two-hundred and thirty carcasses were swabbed and analysed by classical microbiological methods for total E. coli counts and for the presence of pathogenic E. coli. The E. coli counts were high, with a 75th percentile of 444.75 CFUs cm(-2). For pathogenic E. coli, more than 7% of the tested carcasses were positive for E. coli O157. Eighteen E. coli O157 strains were isolated and typed by multiplex PCR. The main isolated pathotype (78%) was eae+ stx2+ ehxA+. In addition to E. coli O157, other attaching and effacing E. coli (AEEC) were also detected from carcasses by colony hybridization after pre-enrichment and plating on sorbitol MacConkey agar using eae, stx1 and stx2 probes. Thirty carcasses (13%) on the 230 analysed harboured at least one colony positive for one of the tested probes. These positive carcasses were different from those positive for E. coli O157. Sixty-six colonies (2.9%) positive by colony hybridization were isolated. The majority (60.6%) of the positive strains harboured an enteropathogenic E. coli-like pathotype (eae+ stx-). Only three enterohaemorrhagic E. coli (EHEC)-like (eae+ stx1+) colonies were isolated from the same carcass. These strains did not belong to classical EHEC serotypes. CONCLUSIONS: In this study, the global hygiene of the slaughterhouse was low, as indicated by the high level of E. coli count. The prevalence of both E. coli O157 and other AEEC was also high, representing a real hazard for consumers. SIGNIFICANCE AND IMPACT OF THE STUDY: This is the first study of this type in Algeria, which indicates that the general hygiene of the slaughterhouse must be improved. [less ▲]

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See detailLyophilized Preparations Of Bacteriocinogenic Lactobacillus Curvatus And Lactococcus Lactis Subsp Lactis As Potential Protective Adjuncts To Control Listeria Monocytogenes In Dry-Fermented Sausages
Benkerroum, N.; Daoudi, A.; Hamraoui, T. et al

in Journal of Applied Microbiology (2005), 98(1),

Methyl oleate was used as a primary carbon source and as an alternative inducer for the production of an extracellular lipase, Lip2, in Y. lipol.vtica strain LgX64.81 grown in a 20-1 bioreactor. The ... [more ▼]

Methyl oleate was used as a primary carbon source and as an alternative inducer for the production of an extracellular lipase, Lip2, in Y. lipol.vtica strain LgX64.81 grown in a 20-1 bioreactor. The lipase-encoding gene, LIP2, was investigated during culture on methyl oleate using a pLIP2-LacZ reporter fusion and we provide evidence for the involvement of methyl oleate in its regulation. [less ▲]

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See detailGenetic Characterization Of The Yeast Pichia Anomala (Strain K), An Antagonist Of Postharvest Diseases Of Apple
Friel, D.; Vandenbol, Micheline ULg; Jijakli, Mohamed ULg

in Journal of Applied Microbiology (2005), 98(3),

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See detailVerotoxigenic Escherichia coli from animals, humans and foods: who's who?
Mainil, Jacques ULg; Daube, Georges ULg

in Journal of Applied Microbiology (2005), 98(6), 1332-1344

Verocytotoxigenic (shigatoxigenic) and enterohaemorrhagic Escherichia coli, VTEC ( STEC) and EHEC, produce a toxin active on Vero cells in vitro. VTEC and EHEC have been isolated from humans and different ... [more ▼]

Verocytotoxigenic (shigatoxigenic) and enterohaemorrhagic Escherichia coli, VTEC ( STEC) and EHEC, produce a toxin active on Vero cells in vitro. VTEC and EHEC have been isolated from humans and different animal species, mainly ruminants and pigs. The verocytotoxins, also named shiga toxins (Stx), are active in vivo on the endothelial cells of the blood vessels of the gastro-intestinal mucosa, the kidneys, the brain, and other tissues of humans and piglets, leading to fluid leakage or haemorrhages. Conversely, their role in diseases of young ruminants remains unclear. Adult ruminants can also act as asymptomatic carriers of VTEC and EHEC strains similar to those causing diseases in humans. And they are incriminated as an important source of direct or indirect contamination of humans by the most famous EHEC strain belonging to the O157: H7 serotype, through faecal contamination of either foods of animal origin, or other foodstuffs ( fruit, vegetables, etc.), or the environment. But dozens of non-O157 human and ruminant VTEC and EHEC strains with similar general and virulence-associated properties, have been described, whose epidemiology is much less well understood. The purpose of this review manuscript is to describe and compare the properties of human, ruminant and food VTEC and EHEC strains. [less ▲]

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See detailRole of lipopeptides produced by Bacillus subtilis GA1 in the reduction of grey mould disease caused by Botrytis cinerea on apple
Toure, Y.; Ongena, MARC ULg; Jacques, P. et al

in Journal of Applied Microbiology (2004), 96(5), 1151-1160

AIM: Test of Bacillus subtilis strain GA1 for its potential to control grey mould disease of apple caused by Botrytis cinerea. METHODS AND RESULTS: GA1 was first tested for its ability to antagonize in ... [more ▼]

AIM: Test of Bacillus subtilis strain GA1 for its potential to control grey mould disease of apple caused by Botrytis cinerea. METHODS AND RESULTS: GA1 was first tested for its ability to antagonize in vitro the growth of a wide variety of plant pathogenic fungi responsible for diseases of economical importance. The potential of strain GA1 to reduce post-harvest infection caused by B. cinerea was tested on apples by treating artificially wounded fruits with endospore suspensions. Strain GA1 was very effective at reducing disease incidence during the first 5 days following pathogen inoculation and a 80% protection level was maintained over the next 10 days. Treatment of fruits with an extract of GA1 culture supernatant also exerted a strong preventive effect on the development of grey mould. Further analysis of this extract revealed that strain GA1 produces a wide variety of antifungal lipopeptide isomers from the iturin, fengycin and surfactin families. A strong evidence for the involvement of such compounds in disease reduction arose from the recovery of fengycins from protected fruit sites colonized by bacterial cells. CONCLUSIONS: The results presented here demonstrate that, despite unfavourable pH, B. subtilis endospores inoculated on apple pulp can readily germinate allowing significant cell populations to establish and efficient in vivo synthesis of lipopeptides which could be related to grey mould reduction. SIGNIFICANCE AND IMPACT OF THE STUDY: This work enables for the first time to correlate the strong protective effect of a particular B. subtilis strain against grey mould with in situ production of fengycins in infected sites of apple fruits. [less ▲]

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See detailCarbon and nitrogen sources modulate lipase production in the yeast Yarrowia lipolytica
Fickers, Patrick ULg; Nicaud, J. M.; Gaillardin, C. et al

in Journal of Applied Microbiology (2004), 96(4), 742-749

AIMS: To analyse the influence of nitrogen and carbon sources on extracellular lipase production by Yarrowia lipolytica-overproducing mutant in order to optimize its production in large-scale bioreactors ... [more ▼]

AIMS: To analyse the influence of nitrogen and carbon sources on extracellular lipase production by Yarrowia lipolytica-overproducing mutant in order to optimize its production in large-scale bioreactors. METHODS AND RESULTS: The level of lipase production and LIP2 induction, measured using an LIP2-LacZ reporter gene, were compared for different carbon and nitrogen sources and for different concentrations. The localization of the enzyme during growth was also determined by Western blotting analysis using a six-histidine-tagged lipase. SIGNIFICANCE AND IMPACT OF THE STUDY: Tryptone N1 and oleic acid are the most suitable nitrogen and carbon sources for the production of the extracellular lipase by the Y. lipolytica mutant. Higher levels of lipase production were obtained as the tryptone concentration increased in the culture medium. Such a positive correlation was not observed with oleic acid media where the highest lipolytic productivities were obtained in the presence of low concentration. We also demonstrate that in the presence of oleic acid, lipase is cell-bound during the growth phase before being released in the media. CONCLUSIONS: This work provides a better understanding of the mechanism controlling LIP2 expression and, thus, extracellular lipase production in the yeast Y. lipolytica. [less ▲]

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See detailMechanisms underlying the toxicity of lactone aroma compounds towards the producing yeast cells
Aguedo, Mario ULg; Beney, L.; Waché, Y. et al

in Journal of Applied Microbiology (2003), 94(2), 258-265

Aims: To study the fundamental mechanisms of toxicity of the fruity aroma compound γ-decalactone, that lead to alterations in cell viability during its biotechnological production by yeast cells; Yarrowia ... [more ▼]

Aims: To study the fundamental mechanisms of toxicity of the fruity aroma compound γ-decalactone, that lead to alterations in cell viability during its biotechnological production by yeast cells; Yarrowia lipolytica that is able to produce high amounts of this metabolite was used here as a model. Methods and Results: Lactone concentrations above 150 mg l-1 inhibited cell growth, depolarized the living cells and increased membrane fluidity. Infrared spectroscopic measurements revealed that the introduction of the lactone into model phospholipid bilayers, decreased the phase transition temperature. Moreover, the H+-ATPase activity in membrane preparations was strongly affected by the presence of the lactone. On the other hand, only a slight decrease in the intracellular pH occurred. Conclusions: We propose that the toxic effects of γ-decalactone on yeast may be initially linked to a strong interaction of the compound with cell membrane lipids and components. Significance and Impact of the Study: These findings may enable the elaboration of strategies to improve yeast cell viability during the process of lactones bioproduction. [less ▲]