33 research outputs found

    Potential biocontrol of fumonisin b1 production by fusarium verticillioides under different ecophysiological conditions in maize

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    Fusarium verticillioides contaminates maize with the fumonisin group of mycotoxins for which there are strict legislative limits in many countries including the EU. The objectives of this project were (a) to examine the microbial diversity of maize samples from different regions and isolate potential biocontrol agents which could antagonize F. verticillioides and reduce fumonisin B1 (FB1) production, (b) to screen the potential biocontrol candidates using antagonistic interaction assays and different ratios of inoculum on maize-based media and on maize kernels to try and control FB1 production, (c) to examine whether the potential control achieved was due to nutritional partitioning and relative utilization patterns of antagonists and pathogen, and (d) to examine the effects of best biocontrol agents on FUM1 gene expression and FB1 production on maize cobs of three different ripening stages. ...[cont.

    Efficacy of potential biocontrol agents for control of Fusarium verticillioides and fumonisin B1 under different environmental conditions

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    A mycotoxigenic strain of Fusarium verticillioides previously isolated from Malaysian maize kernels and identified morphologically and molecularly was used in the present work. The objectives were (1) to screen the competitiveness of three potential antagonists isolated from Malaysian maize and three other known candidates for control of growth of F. verticillioides in vitro based on interaction scores, growth rates and hyphal area of F. verticillioides, and (2) to examine the best candidates using different spore/cell ratios on milled maize agar at different water activity conditions on relative control of fumonisin B1 (FB1). Three fungi and three bacteria (BCAs 1-6) were examined for antagonistic effects against F. verticillioides in dual-culture assays. These showed that all fungal candidates intermingled with F. verticillioides while all bacterial candidates inhibited F. verticillioides on contact or at a distance, which in turn decreased the growth rates and hyphal area of F. verticillioides significantly. Although BCA1 (Clonostachys rosea 016) did not inhibit growth or hyphal area of F. verticillioides, it was included in FB1 inhibition studies with other bacterial candidates (BCA4, Streptomyces sp. AS1; BCA5, Gram-negative rod; BCA6, Enterobacter hormaechei) because of its established mycoparasitism. The FB1 inhibition studies were conducted on milled maize agar with different spore/cell ratios of pathogen:antagonist mixtures at 0.95/0.98 water activity (aw) and 25 °C for 14 days. FB1 biosynthesis for all treatments was significantly higher at 0.95 than 0.98 aw. Of the four antagonists tested, the best was BCA1 which inhibited FB1 biosynthesis by 73 and 100% at 0.95 and 0.98 aw, respectively. BCA5 was the next best, resulting in 38 and 78% FB1 inhibition at 0.95 and 0.98 aw, respectively. The pathogen:antagonist ratios for BCA1 and BCA5 showed best results at 50:50 and 25:75. These results were discussed in context of using biocontrol agents to minimise fumonisins in maize

    Edible mushrooms from Malaysia; a literature review on their nutritional and medicinal properties

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    Mushrooms have been consumed by mankind for millennia. In Malaysia, there are many species of edible mushrooms which are either cultivated (Agaricus spp., Auricularia spp., Pleurotus spp.) or harvested in the wild (Ganoderma spp., Polyporus spp., Termitomyces spp.). With the advancement of technology, numerous discoveries have been made that elucidated the nutritional (high in fibres, proteins, vitamins; low in fats, cholesterols, sodium) and medicinal (anti-oxidative, anti-hypertensive, neuritogenesis) properties of edible mushrooms, all of which are highly beneficial for the maintenance of human health and well-being. This review thus compiles and documents the available literatures on edible mushrooms reported from Malaysia complete with scientific, English, and vernacular names for future references; provides a comprehensive and updated overview on the nutritional and medicinal properties edible mushrooms reported from Malaysia; and identifies the research gaps to promote further research and development on edible mushrooms reported from Malaysia. Overall, Malaysia is and remains a natural repository for wild and cultivated edible mushrooms. Deeper investigation on their nutritional and medicinal properties will certainly serve as an impetus for economic as well as scientific progress

    Relationship between environmental conditions, carbon utilisation patterns and Niche Overlap Indices of the mycotoxigenic species Fusarium verticillioides and the biocontrol agent Clonostachys rosea

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    Recently, it was shown that a strain of the fungal antagonist Clonostachys rosea 016 was able to inhibit fumonisin B1 mycotoxin production by Fusarium verticillioides FV1 when using different ratios of spores of each species in vitro. The objectives of the present work were therefore to: (a) compare the nutritional utilisation patterns and rates of uptake of key C-sources in maize by the antagonist C. rosea 016 and that by the pathogen F. verticillioides FV1; (b) examine their Niche Overlap Indices (NOI) under different interacting environmental conditions; and (c) evaluate whether the rate of utilisation of key maize C-sources influenced the competitiveness of either species using the Bioscreen®. It was found that water potential (Ψ) × temperature interactions had significant impacts on C-source utilisation patterns by C. rosea 016 and the pathogen. The NOIs, based on the utilisation of the C-sources by each strain divided by those utilised in common, showed that the antagonist and the pathogen occupied similar niches at −0.70 MPa Ψ+30 °C and −2.8 MPa Ψ+25 °C. Under the other conditions tested, they appeared to occupy separate niches suggesting niche exclusion. Temporal C-source utilisation patterns were then compared under different Ψ × temperature treatments. This showed that the dominant maize-based C-sources utilised by the pathogen and the antagonist were different. The pathogen F. verticillioides FV1 utilised carbohydrates rapidly followed by amino acids and then one fatty acid, palmitic acid. The antagonist C. rosea 016 utilised both carbohydrates and amino acids at a similar rate but more slowly than the pathogen. There were also differences in the utilisation of some individual amino acids and carbohydrates which might explain the occupation of different niches under some interacting environmental conditions. These findings are discussed in the context of why some competitors are able to inhibit mycotoxin production while others cannot

    Effect of salam [Syzygium polyanthum (Wigt) Walp.] leaves extract on the microorganism population in chicken meat and shrimp and their sensory

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    Recently, there has been an increasing demand and interest in developing plant extracts as natural food sanitizer, owing to their antimicrobial properties. Hence, the aim of this study was to investigate the effect of salam (Syzygium polyanthum L.) leaves methanolics extract on the number of microflora on chicken meat and shrimp. Salam leaves extract at different concentrations (0.0%, 0.1%, 1.00%) and exposure times (5, and 10 min) used to treat chicken meat and shrimp by using dilution method. Result showed that the total plate count and Staphylococcus aureus had been detected in untreated chicken and shrimp samples with 6.66 ± 0.12, 8.66 ± 0.15 and 7.25 ± 0.21, 6.54 ± 0.21, respectively. However, there was no Escherichia coli, Salmonella spp. and Vibrio cholera detected in both samples. The number of total plate count (TPC) and S. aureus in chicken meat and shrimp were starting to reduce significantly at 0.01% concentration of salam leaves extract for 5 minutes of exposure time compared to initial count. There was no significantly different between exposure times. The highest reduction in number of microorganism population was at treatment with 1.0% extract for 10 min where TPC was reduced from 6.66 ± 0.12 to 0.00 ± 0.00 log10 CFU/ml, and from 8.66 ± 0.15 to 4.88 ± 0.00 log10 CFU/ml in shrimp while S. aureus reduced from 7.25 ± 0.21 to 3.88 ± 0.01 and from 6.54 ± 0.21 to 4.92 ± 0.04 in chicken and shrimp, respectively. For the sensory acceptability, overall acceptability were accepted by panellists until treatment 0.10% for 5 min and 10 min of soaking time. In conclusion, salam leaves extract might be developed as natural sanitizer for rinsing raw food materials such as chicken meat and shrimp

    Biocontrol of mycotoxins: dynamics and mechanisms of action

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    This paper discusses the relationship between biocontrol agents (BCAs) and mycotoxigenic fungi and mycotoxin control. In most cases BCAs are examined for control of growth of fungal pathogens and disease symptoms. However, for mycotoxin control the approach and focus needs to be different. The mechanism of action and the inoculum dose necessary for control of toxin production by Aspegillus, Penicillium and Fusarium species may be different from that for traditional fungal plant pathogens. The mechanisms of action, the relative inoculum potential and the impact that interacting environmental conditions have on control of key components of the life cycle of mycotoxigenic fungi are considered. The practical aspects of production and formulation hurdles are discussed and potential future approaches and strategies which may need to be considered for more effective biocontrol of mycotoxigenic fungi and mycotoxins are presented

    Reduction of Aspergillus spp. and aflatoxins in peanut sauce processing by oil-less frying of chilli powder and retort processing

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    Among the many roles played by small and medium enterprises (SMEs) in the food industry is the production of heritage foods such as peanut sauce. Unfortunately, the safety of peanut sauce is not always assured as the processing line is not controlled. Peanut sauce is usually made of peanuts and chilli, and these commodities are normally contaminated with Aspergillus spp. and aflatoxins (AFs). Hence, the objective of this study was to evaluate the practices related to reduction of AF hazard and the effect of interventions in peanut sauce processing. Peanut samples were collected from each step of peanut sauce processing from a small peanut sauce company according to four designs: (1) control; (2) oil-less frying of chilli powder; (3) addition of retort processing; and (4) combination of oil-less frying of chilli powder and retort processing. Oil-less frying of chilli powder (Design 2) reduced total AFs by 33–41%, retort processing (Design 3) reduced total AFs by 49%, while combination of these two thermal processes (Design 4) significantly reduced total AFs, by 57%. The present work demonstrated that Design 4 yielded the highest reduction of total AFs and is therefore recommended to be employed by SME companies

    Formulation of maize- and peanut-based semi-synthetic growth media for the ecophysiological studies of aflatoxigenic Aspergillus flavus in maize and peanut agro-ecosystems

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    In studying the ecophysiology of fungal phytopathogens, several stages are involved (in vitro, greenhouse, in planta). Most in vitro studies extensively utilise the general growth media such as Potato Dextrose Agar and Malt Extract Agar. Although the crop components in these media serve as excellent carbon sources and yield luxuriant growth, they are not naturally contaminated with Aspergillus flavus and thus might result in under- or overestimation of its actual toxigenic potentials. Empirical data on the formulation of semi-synthetic growth medium mimicking the natural crop commonly contaminated by A. flavus for the ecophysiological studies in vitro are scarce. The present work was aimed at investigating the ecophysiology of A. flavus on commercial growth media (PDA, MEA); formulating maize- and peanut-based semi-synthetic growth media using two methods of raw material preparation (milling, hot water extraction) at different concentrations (1, 3, 5, 7, 9% w/v), and comparing the ecophysiological parameters between commercial and formulated growth media. Growth rates were obtained by computing the hyphal expansion data into y = mx + c equation. AFB1 was quantified using high performance liquid chromatography with fluorescence detector. Formulated media were found to yield significantly higher growth rates when compared to commercial media. However, commercial media yielded significantly higher AFB1 when compared to all formulated media. Between the two formulations, milling yielded significantly higher growth rates and AFB1 when compared to hot water extraction. Although in vitro data cannot directly extrapolate in planta performance, results obtained in the present work can be used to gauge the actual toxigenic potential of A. flavus in maize and peanut agro-ecosystems

    Prevalence of Aspergillus spp. and occurrence of aflatoxins in peanut sauce processing by peanut sauce manufacturers

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    The aims of the present work were to determine the prevalence of Aspergillus spp. and occurrence of aflatoxins (AFs) along the peanut sauce processing line from different peanut sauce companies in Malaysia, and to determine to which extent peanut sauce processing steps employed by the peanut sauce industries could efficiently reduce AFs in peanut sauce. Peanut and chili samples were collected at each processing step along the peanut sauce production from three peanut sauce companies which were different in companies’ profile. Peanut samples from Companies B (87.5%) and C (100%) were contaminated with AFs. Of these, 12.5% (Company B) and 75% (Company C) samples exceeded the Malaysian regulatory limit. None of the samples from Company A was contaminated. The steps efficient in reducing AFs in peanut sauce identified in the present work were (i) safety monitoring of raw materials, (ii) sorting of raw materials, and (iii) heat treatment of raw materials

    Phytopathogenic organisms and mycotoxigenic fungi: Why do we control one and neglect the other? A biological control perspective in Malaysia

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    In this review, we present the current information on development and applications of biological control against phytopathogenic organisms as well as mycotoxigenic fungi in Malaysia as part of the integrated pest management (IPM) programs in a collective effort to achieve food security. Although the biological control of phytopathogenic organisms of economically important crops is well established and widely practiced in Malaysia with considerable success, the same cannot be said for mycotoxigenic fungi. This is surprising because the year round hot and humid Malaysian tropical climate is very conducive for the colonization of mycotoxigenic fungi and the potential contamination with mycotoxins. This suggests that less focus has been made on the control of mycotoxigenic species in the genera Aspergillus, Fusarium, and Penicillium in Malaysia, despite the food security and health implications of exposure to the mycotoxins produced by these species. At present, there is limited research in Malaysia related to biological control of the key mycotoxins, especially aflatoxins, Fusarium‐related mycotoxins, and ochratoxin A, in key food and feed chains. The expected threats of climate change, its impacts on both plant physiology and the proliferation of mycotoxigenic fungi, and the contamination of food and feed commodities with mycotoxins, including the discovery of masked mycotoxins, will pose significant new global challenges that will impact on mycotoxin management strategies in food and feed crops worldwide. Future research, especially in Malaysia, should urgently focus on these challenges to develop IPM strategies that include biological control for minimizing mycotoxins in economically important food and feed chains for the benefit of ensuring food safety and food security under climate change scenario
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