Major Food Safety Research Articles

Species composition, toxigenic potential and aggressiveness of Fusarium isolates causing Head Blight of barley in Uruguay

Fusarium Head Blight (FHB) is a major constraint to barley production that substantially reduces yield and grain quality. FHB is also a major food safety concern because FHB pathogens contaminate grain with trichothecenes and other mycotoxins. DNA sequence-based analyses and in-vitro toxin assessments were used to characterize the species and trichothecene chemotype composition of FHB pathogens on barley in Uruguay. F. graminearum was the dominant species (89.7%), and three other members of the F. graminearum species complex (FGSC) were identified as FHB pathogens of barley in Uruguay for the first time. Other minor contributors to FHB species diversity included F. poae, F. avenaceum, F. pseudograminearum and an unnamed species from the F. incarnatum-equiseti species complex (FIESC). Most isolates (89.7%) had the 15-acetyldeoxynivalenol (15-ADON) trichothecene type. However, the results expanded the known area of occurrence within Uruguay for the nivalenol (NIV) toxin type, which was observed among isolates from three species of the FGSC, F. pseudograminearum, and F. poae. Isolates with the 3-acetyldeoxynivalenol (3-ADON) or NX-2 toxin types were not observed, although a previously published multilocus genotyping assay was updated to identify NX-2 strains. Analyses of population structure and comparisons with FHB isolates from wheat in Uruguay indicated that F. graminearum constitutes a single genetic population with no evidence of population differentiation related to the sampled hosts. Inter and intraspecific differences were observed in aggressiveness toward four barley genotypes with different levels of resistance to FHB, and in general nivalenol producers were the least aggressive isolates. Sensitivity to metconazole was approximately 10 times higher than was detected for tebuconazole. This is the first report regarding tebuconazole and metconazole sensitivity for Fusarium species causing FHB in barley in Uruguay, and constitutes an important starting point for monitoring temporal or spatial changes in FGSC sensitivity, which is critical to define FHB management practices.

Electrochemical DNA biosensor for potential carcinogen detection in food sample

The presence of carcinogens in food is a major food safety concern. A nanocomposite-based electrochemical DNA biosensor was constructed for potential carcinogen detection in food samples by immobilizing amine terminated single stranded DNA onto silica nanospheres deposited onto a screen-printed electrode modified using gold nanoparticles. The effect of three different DNA sequences: 15-base guanine, 24-base guanine and 24-base adenine-thymine rich DNA on carcinogen (formaldehyde and acrylamide) detection was evaluated. The competitive binding of the DNA with the carcinogen and electroactive indicator, Methylene blue (MB) was measured using differential pulse voltammetry. Optimization studies were conducted for MB concentration and accumulation time, DNA concentration, buffer concentration, pH and ionic strength. Overall, the 24-base guanine rich DNA yielded the best results with a detection limit of 0.0001 ppm, linear range between 0.0001 ppm and 0.1 ppm and reproducibility below 5% R.S.D. Finally, the results obtained using the biosensor were validated using Ames test.

Anticipation of food safety and fraud issues: ISAR - A new screening tool to monitor food prices and commodity flows

Despite major efforts, food safety and food fraud issues continue to appear, showing the need for an improved risk anticipation to enhance consumer protection. To this end, we need a holistic view on the food production beyond the classical farm to fork principle and consider developments in- and outside the food chain. Commodity flows and prices are considered as relevant drivers for the emergence of food safety and fraud issues. To conveniently obtain information on these drivers and to monitor their changes, we developed a tool to analyze the volume, origin and price of foods imported to Germany, based on data of the German Foreign Trade Statistic. The ISAR-Tool (Import Screening for the Anticipation of Food Risks) facilitates a descriptive analysis of the import data of about 2400 different food items imported from 220 countries and an automated analysis of the data for a systematic detection of unexpected changes in import volumes and prices. For the automated approach, time series analyses using SARIMA and ETS models are applied and data points outside the model-based 99% prediction intervals are considered as potentially relevant changes. Monthly, more than 2000 of such changes are detected, leaving us with the challenging task of their evaluation for food safety and food fraud. To deal with the vast amount of results, of which the great majority cannot be linked to food safety or fraud issues, we implemented prioritization routines, and the 200 most critical results are considered for further expert evaluation. Despite remaining challenges in the performed evaluation process of the automated analysis, the described approach facilitates already at this stage an improved identification of food safety and food fraud hazards and the implementation of more targeted food safety controls, as shown in this paper. Our most prominent example of an identified food fraud and food safety risk was the detection of massive adulterations of hazelnut products with almonds and cashews, which were associated to the observed all-time high in hazelnut prices. Based on our findings, we conclude that the ISAR-Tool and the described analyses of commodity flows and prices can be important elements in the anticipation of risks and enable an enhanced consumer protection.

Regional differences in the composition of Fusarium Head Blight pathogens and mycotoxins associated with wheat in Mexico

Fusarium Head Blight (FHB) is a destructive disease of small grain cereals and a major food safety concern. Epidemics result in substantial yield losses, reduction in crop quality, and contamination of grains with trichothecenes and other mycotoxins. A number of different fusaria can cause FHB, and there are significant regional differences in the occurrence and prevalence of FHB pathogen species and their associated mycotoxins. Information on FHB pathogen and mycotoxin diversity in Mexico has been extremely limited, but is needed to improve disease and mycotoxin control efforts. To address this, we used a combination of DNA sequence-based methods and in-vitro toxin analyses to characterize FHB isolates collected from symptomatic wheat in Mexico during the 2013 and 2014 growing seasons. Among 116 Fusarium isolates, we identified five species complexes including nine named Fusarium species and 30 isolates representing unnamed or potentially novel species. Significant regional differences (P < 0.001) in pathogen composition were observed, with F. boothii accounting for >90% of isolates from the Mixteca region in southern Mexico, whereas F. avenaceum and related members of the F. tricinctum species complex (FTSC) accounted for nearly 75% of isolates from the Highlands region in Central Mexico. F. graminearum, which is the dominant FHB pathogen in other parts of North America, was not present among the isolates from Mexico. F. boothii isolates had the 15-acetyldeoxynivalenol toxin type, and some of the minor FHB species produced trichothecenes, such as nivalenol, T-2 toxin and diacetoxyscirpenol. None of the FTSC isolates tested was able to produce trichothecenes, but many produced chlamydosporol and enniatin B.

Complete Genome Sequence of a Ciprofloxacin-Resistant Salmonella enterica subsp. enterica Serovar Kentucky Sequence Type 198 Strain, PU131, Isolated from a Human Patient in Washington State.

ABSTRACTStrains of the ciprofloxacin-resistant (Cipr) Salmonella enterica subsp. enterica serovar Kentucky sequence type 198 (ST198) have rapidly and extensively disseminated globally to become a major food safety and public health concern. Here, we report the complete genome sequence of a Cipr S. Kentucky ST198 strain, PU131, isolated from a human patient in Washington State (USA).

Farm Science Centre and On-Farm Food Safety Training in India: Perspectives of Programme Coordinators

Foodborne illness due to consumption of contaminated food and water is one of the major public health concerns in India. This assessment study primarily intended to contribute to the discourse on engaging Krishi Vigyan Kendra (KVK) (Farm Science Centre) in training farmers to adopt food safety practices on their farms. A questionnaire was developed, validated and administered online to Programme Coordinators (PCs) of KVKs. The results of the assessment showed that PCs are not only familiar with Good Agricultural Practices (GAPs) but also value the significance of food safety training. Excessive use of pesticides, lack of hygienic practices and improper washing of vegetables were identified as the major food safety concerns in KVK districts. The result showed that KVKs with food safety Subject Matter Specialists (SMS) are more likely to offer food safety training to farmers than KVKs without them. A need was also expressed for having a food safety SMS to deliver food safety programs. Lack of workers’ food safety awareness and limited field workers were identified as major programming barriers. KVKs need to develop strategies and allocate resources to overcome the programming barriers to accommodate and prioritise on-farm food safety awareness programs in their annual action plans. As one of the major component of public Extension system in India and with its wide presence, KVKs should take a lead role in offering food safety training to farmers as well as Extension professionals.

Packaging and Microbial Status of Local &amp; Branded Bakery Products: A Comparative Study on Jessore Region, Bangladesh

Background: Most of the people in Bangladesh due to their hectic lifestyles are now increasingly dependent on various bakery products as a source of ready-to-eat foods. Generally, majority of these widely consumed bakery products mainly bread and cakes are supplied by local bakeries. Any chance of unwanted microbial contamination of these popular food products due to any poor manufacturing, handling and packaging practices can lead to major food safety and public health problems. Objectives: This study was aimed to determine and compare the microbiological quality of the locally produced bakery products of Jessore based bakeries with those of branded bakery products produced by renowned food bakeries as well as assessing their relative packaging conditions in respective shops. Method: 120 bakery shops were randomly selected in Jessore region for a questionnaire based data collection. Three types of bakery shops; tea stalls, confectionaries, and variety stores were inspected against their vending extent of branded and local bakery products with associated packaging and visual appearance. Later, 20 samples of cakes (n=10) and breads (n=10) were tested to determine the total fungal count (TFC), total bacterial count (TBC), total Staphylococcus aureus (TSA), total Enterobacteriaceae (TE), and total coliforms count (TC) in cfu/g. For required statistical data analysis Statistical Package for Social Science (SPSS)-16 software was used. Results: Most of the open (44.6%) and spoiled (49.4%) bakery products were found in the Tea stalls. Locally produced bakery products had greater percentage of spoiled bread and cakes compared to their branded counterparts. Breads were more visually spoiled than cakes irrespective of their brands. The number of visually spoiled breads and cakes positively and significantly increased with the number of opened or partially sealed breads and cakes (r=0.64, p<0.01). Microbial counts (cfu/g) in local products were always higher than that of their branded counterparts. Bacterial counts (cfu/g) in branded products were always lower than local counterparts (Bread, 12.8 ×107 ± 3.63×107 vs 37.8×107 ± 19.1×107, p=0.024 and Cake, 10.2×107 ± 3.20×107 vs 30.8×107 ± 21.7×107, p=0.003). Coliform count in unpacked sample (4.7×104 cfu/g) was observed much higher than the safety limit for human consumption. Bread and cake produced by local bakeries showed lower standard in packaging and microbial quality. A better manufacturing and packaging initiatives can be introduced to avoid its related food safety concerns in future.

From proteomics to ionomics: Soybean genetic improvement for better food safety

Soybean is a major protein and oilseed crop for food and livestock feed production, which is increasingly utilized in the food industry due to its favorable protein content and a superior overall seed composition with a high nutritional value. However, some of the soybean seed components have the potential to reduce the value of soy-food products as they are posing different food safety risks. Therefore, the objective of the present review was to evaluate options of soybean genetic improvement for the development of food-grade soybeans with a focus on food safety traits. To date, useful genetic variation in soybean germplasm collections and breeding materials has been described for protein components such as allergens or anti-nutritional factors, for fatty acid composition relevant to food safety, and for toxic heavy metal accumulation. Due to the progress in genomic research, genetic markers are available for assisting the introgression of major food safety traits into breeding populations, and the genetic mechanisms behind particular food safety traits have been clarified. Moreover, analytical methods from the fields of proteomics or ionomics are helpful for validating selection response and for monitoring quality features across genotypes. As consumer demand for food safety is steadily increasing, plant breeding approaches are gaining in importance as they can provide high-quality soybean raw materials to the food industry. For implementing better food safety on the consumer level, however, it appears that coordinated action between plant breeding and genetic research, food processing and marketing of products needs to be developed.

Rapid identification of gutter oil by detecting the capsaicin using surface enhanced Raman spectroscopy

AbstractAccurate determination of the gutter oil represents a major food safety challenge. Here, we propose to use the surface enhanced Raman spectroscopy (SERS) with silver nanorod array substrates to detect the capsaicin, a marker of the gutter oil that is difficult to remove. The capsaicin has several characteristic SERS peaks at Δv = 807 cm−1, Δv = 1, 264 cm−1, and so forth, which correspond to the C39‐C37‐C43 stretching vibrational mode at the alkyl chain, the ring stretching vibrational mode, and so forth, confirmed by our density functional theory calculation. This SERS‐based method enabled the rapid and highly sensitive detection of the gutter oil with minimum pretreatment. The concentration dependent SERS investigation shows that the SERS intensity of these characteristic peaks has a linear relationship with the capsaicin concentration when 1 mg/L &lt; C &lt; 60 mg/L. By combining a liquid phase extraction method and the SERS detection strategy, the capsaicin concentration as low as 30 mg/L can be detected from inoculated corn oil samples.

Penicillin-binding protein encoded by pbp4 is involved in mediating copper stress in Listeria monocytogenes.

Listeria monocytogenes raises major food safety and public health concerns due to its potential for severe foodborne disease and persistent colonization of food processing facilities. Copper is often employed to control pathogens in agriculture and is increasingly used in healthcare facilities, but mechanisms mediating tolerance of L. monocytogenes to copper remain poorly understood. A mariner-based mutant library of L. monocytogenes 2011L-2858, implicated in the 2011 listeriosis outbreak via whole cantaloupe, was screened for growth at sublethal levels of copper yielding mutant G2B4 with decreased copper tolerance. The transposon was localized in pbp4 (lmo2229 homolog), encoding a penicillin-binding protein (PBP). In addition to reduced copper tolerance, G2B4 exhibited increased susceptibility to β-lactam antibiotics, reduced biofilm formation and reduced virulence in the Galleria mellonella model. Mutant phenotypes were fully restored upon genetic complementation of G2B4 with intact pbp4. Findings provide the first evidence for the role of a PBP in copper tolerance of L. monocytogenes and suggest that pbp4 may be a suitable target to enable the use of lower levels of copper or enhance the effectiveness of levels currently in use. Given the wide distribution of PBPs and their highly conserved nature, this could have profound impacts in regard to ecology and control of L. monocytogenes and other microorganisms.

Development of a PCR-RFLP method based on the transcription elongation factor 1-α gene to differentiate Fusarium graminearum from other species within the Fusarium graminearum species complex

Fusarium head blight (FHB) is a destructive disease of cereals crops worldwide and a major food safety concern due to grain contamination with trichothecenes and other mycotoxins. Fusarium graminearum, a member of the Fusarium graminearum species complex (FGSC) is the dominant FHB pathogen in many parts of the world. However, a number of other Fusarium species, including other members of the FGSC, may also be present for example in Argentina, New Zealand, Ethiopia, Nepal, Unites States in cereals such as wheat and barley. Proper species identification is critical to research aimed at improving disease and mycotoxin control programs. Identification of Fusarium species is are often unreliable by traditional, as many species are morphologically cryptic. DNA sequence-based methods offer a reliable means of species identification, but can be expensive when applied to the analyses of population samples. To facilitate identification of the major causative agent of FHB, this work describes an easy and inexpensive method to differentiate F. graminearum from the remaining species within the FGSC and from the other common Fusarium species causing FHB in cereals. The developed method is based on a PCR-RFLP of the transcription elongation factor (TEF 1-α) gene using the restriction enzyme BsaHI.

Phytochelatin Synthase has Contrasting Effects on Cadmium and Arsenic Accumulation in Rice Grains

Phytochelatin (PC) synthesis has been well demonstrated as a major metal tolerance mechanism in Arabidopsis thaliana, whereas its contribution to long-distance element transport especially in monocots remains elusive. Using rice as a cereal model, we examined physiological roles of Oryza sativa phytochelatin synthase 1 (OsPCS1) in the distribution and detoxification of arsenic (As) and cadmium (Cd), two toxic elements associated with major food safety concerns. First, we isolated four different transcript variants of OsPCS1 as well as one from OsPCS2. Quantitative real-time reverse transcription–PCR (RT-PCR) of each OsPCS transcript in rice seedlings suggested that expression of OsPCS1full, the longest OsPCS1 variant, was most abundant, followed by OsPCS2. Heterologous expression of OsPCS variants in PCS-deficient mutants of Schizosaccharomyces pombe and A. thaliana suggested that OsPCS1full possessed PCS activity in response to As(III) and Cd while the activity of other PCS variants was very low. To address physiological functions in toxic element tolerance and accumulation, two independent OsPCS1 mutant rice lines (a T-DNA and a Tos17 insertion line) were identified. The OsPCS1 mutants exhibited increased sensitivity to As(III) and Cd in hydroponic experiments, showing the importance of OsPCS1-dependent PC synthesis for rice As(III) and Cd tolerance. Elemental analyses of rice plants grown in soil with environmentally relevant As and Cd concentrations showed increased As accumulation and decreased Cd accumulation in grains of the T-DNA line. The Tos17 mutant also exhibited the reduced Cd accumulation phenotype. These contrasting effects on As and Cd distribution to grains suggest the existence of at least partially distinct PC-dependent pathways for As and Cd.

Genotypic Regulation of Aflatoxin Accumulation but Not Aspergillus Fungal Growth upon Post-Harvest Infection of Peanut (Arachis hypogaea L.) Seeds.

Aflatoxin contamination is a major economic and food safety concern for the peanut industry that largely could be mitigated by genetic resistance. To screen peanut for aflatoxin resistance, ten genotypes were infected with a green fluorescent protein (GFP)—expressing Aspergillus flavus strain. Percentages of fungal infected area and fungal GFP signal intensity were documented by visual ratings every 8 h for 72 h after inoculation. Significant genotypic differences in fungal growth rates were documented by repeated measures and area under the disease progress curve (AUDPC) analyses. SICIA (Seed Infection Coverage and Intensity Analyzer), an image processing software, was developed to digitize fungal GFP signals. Data from SICIA image analysis confirmed visual rating results validating its utility for quantifying fungal growth. Among the tested peanut genotypes, NC 3033 and GT-C20 supported the lowest and highest fungal growth on the surface of peanut seeds, respectively. Although differential fungal growth was observed on the surface of peanut seeds, total fungal growth in the seeds was not significantly different across genotypes based on a fluorometric GFP assay. Significant differences in aflatoxin B levels were detected across peanut genotypes. ICG 1471 had the lowest aflatoxin level whereas Florida-07 had the highest. Two-year aflatoxin tests under simulated late-season drought also showed that ICG 1471 had reduced aflatoxin production under pre-harvest field conditions. These results suggest that all peanut genotypes support A. flavus fungal growth yet differentially influence aflatoxin production.

Regulation of Botulinum Neurotoxin Synthesis and Toxin Complex Formation by Arginine and Glucose in Clostridium botulinum ATCC 3502

Botulinum neurotoxin (BoNT), produced by neurotoxigenic clostridia, is the most potent biological toxin known and the causative agent of the paralytic disease botulism. The nutritional, environmental, and genetic regulation of BoNT synthesis, activation, stability, and toxin complex (TC) formation is not well studied. Previous studies indicated that growth and BoNT formation were affected by arginine and glucose in Clostridium botulinum types A and B. In the present study, C. botulinum ATCC 3502 was grown in toxin production medium (TPM) with different levels of arginine and glucose and of three products of arginine metabolism, citrulline, proline, and ornithine. Cultures were analyzed for growth (optical density at 600 nm [OD600]), spore formation, and BoNT and TC formation by Western blotting and immunoprecipitation and for BoNT activity by mouse bioassay. A high level of arginine (20 g/liter) repressed BoNT production approximately 1,000-fold, enhanced growth, slowed lysis, and reduced endospore production by greater than 1,000-fold. Similar effects on toxin production were seen with equivalent levels of citrulline but not ornithine or proline. In TPM lacking glucose, levels of formation of BoNT/A1 and TC were significantly decreased, and extracellular BoNT and TC proteins were partially inactivated after the first day of culture. An understanding of the regulation of C. botulinum growth and BoNT and TC formation should be valuable in defining requirements for BoNT formation in foods and clinical samples, improving the quality of BoNT for pharmaceutical preparations, and elucidating the biological functions of BoNTs for the bacterium.IMPORTANCE Botulinum neurotoxin (BoNT) is a major food safety and bioterrorism concern and is also an important pharmaceutical, and yet the regulation of its synthesis, activation, and stability in culture media, foods, and clinical samples is not well understood. This paper provides insights into the effects of critical nutrients on growth, lysis, spore formation, BoNT and TC production, and stability of BoNTs of C. botulinum We show that for C. botulinum ATCC 3502 cultured in a complex medium, a high level of arginine repressed BoNT expression by ca. 1,000-fold and also strongly reduced sporulation. Arginine stimulated growth and compensated for a lack of glucose. BoNT and toxin complex proteins were partially inactivated in a complex medium lacking glucose. This work should aid in optimizing BoNT production for pharmaceutical uses, and furthermore, an understanding of the nutritional regulation of growth and BoNT formation may provide insights into growth and BoNT formation in foods and clinical samples and into the enigmatic function of BoNTs in nature.

Detection of environmentally hazardous pesticide in fruit and vegetable samples using gold nanoparticles

A new approach for simple, competitive and sensitive, dipstick immunoassay (DIA) was developed to detect organophosphorus pesticide. Residual pesticides such as kitazine in fruits and vegetables are one of the major food safety concerns for consumers in the world. It is the alternative method to nitrocellulose strip (NC) for the detection of harmful pesticides. The matrix effects of different food samples (tomato, cucumber, grapes and orange) were studied in flow through ELISA (Enzyme Linked Immunoassay) and DIA method. Different size morphology was synthesized from gold nanoparticles and bioconjugated to Ig G, which served as the detecting agent confirmed by AFM. The different concentration of organophosphorus in the food sample was detected by the development of purple color in the membrane strips. Among four fruit juices, the grape juice exhibits increased absorbance resulted that the bioconjugated gold nanoparticle is actively detected the kitazine present in the grape juice evidenced by ELISA method has good reproducibility and satisfactory accuracy. The interpretation of the results was visual, and these ELISAs can be used as convenient qualitative tools for the rapid screening ofkitazine residues in food samples.

INTERNATIONAL DIFFUSION OF FOOD SAFETY STANDARDS: THE ROLE OF DOMESTIC CERTIFIERS AND INTERNATIONAL TRADE

AbstractWe examined the cross-national adoption of six major private food safety standards, focusing on the role of certifiers and international trade. Results show that the number of certification bodies existing in the domestic country, food exports, and the proportion of food exports to North America had positive effects on a country's adoption of food safety standards. Distance leads to product differentiation for the standards and therefore disadvantages developing countries in Africa and Asia for adopting the standards, which are all based in the United States or Europe. Providing these countries with better access to certifiers can alleviate this geographic disadvantage.

Food safety in Vietnam: where we are at and what we can learn from international experiences

Food-borne diseases are attracting a lot of attention in Vietnam as a result of repeated episodes of adulterated and unsafe food. In this paper, we provide some perspectives on food safety in Vietnam from the point of view of an international research institution working on food safety with partners in the country. We argue that one of the key issues of food safety in Vietnam is that certain food value chain stakeholders lack ethics, which leads to the production and trading of unsafe foods in order to make profits irrespective of adverse health effects on consumers. In turn, the shortfall in ethical behaviours around food can be attributed to a lack of incentives or motivating factors.Although food safety causes panic in the population, it is unclear how much contaminated food contributes to the burden of food-borne diseases and food poisonings in Vietnam. However, globally, the biggest health problem associated with food are infections from consuming food contaminated with viruses, bacteria or parasites. A major food safety challenge is the inappropriate way of communicating food risks to the public. Another key constraint is the inherent difficulty in managing food in wet markets and from smallholder production. On the other hand, local foods, and local food production and processing are an important cultural asset as well as being essential to food safety, and these aspects can be put at risk if food safety concerns motivate consumers to purchase more imported foods.In this paper, we also discuss good experiences in food safety management from other countries and draw lessons learnt for Vietnam on how to better deal with the current food safety situation.

Biocontrol of Aspergillus flavus in groundnut using Trichoderma harzianum stain kd

Pre-harvest infection of groundnut (Arachis hypogea) during drought stress by strains of Aspergillus flavus and Aspergillus parasiticus is a major health and food safety concern worldwide. The fungi release aflatoxins, which are carcinogenic and hepatotoxic at levels of parts per billion. In this study, a formulated biocontrol agent, Trichoderma harzianum strain kd (Tkd), was used to control Aspergillus flavus infection of groundnut in the field. Groundnut seeds treated with Tkd developed more root biomass than the control (untreated with Tkd). Growth of Trichoderma mycelium from sterilized roots of groundnuts grown on Trichoderma selective media indicates root colonization of the intercellular spaces in groundnut roots by Tkd. Even the control plants showed evidence of root colonization by Trichoderma but at much lower levels. This shows that groundnuts are particularly a compatible host of Trichoderma acting as an endophyte. Under scanning electron microscopy, T. harzianum showed the ability to parasitize A. flavus by coiling around A. flavus hyphae, penetrating and degrading the mycelium of A. flavus. The levels of aflatoxin B1 contamination from Aspergillus infection were determined using a MaxiSignal® ELISA test kit. The aflatoxin levels of A. flavus-inoculated control plants were significantly (p < 0.001) higher than that of the Tkd-treated plants, by 57 and 65%, in two trials. Yields from plants treated with Tkd were 35 and 49% higher than that from the control (untreated with Tkd) plants in these field trials. It can be concluded that application of Tkd to groundnut seeds may reduce infection of the groundnut seeds by Aspergillus flavus, and hence, it may reduce the contamination of the seed by aflatoxin, especially under drought stress condition. Concurrently, Tkd treatment may result in yields being enhanced by more than 35%.

English

Variable sensorial quality of attiek&eacute; (a fermented cassava product like couscous) is mainly due to different types of artisanal starters used for fermentation of cassava dough. Biochemical properties of eleven lactic acid bacteria identified as Lactobacillus plantarum strains isolated from these traditional cassava starters were evaluated in vitro. Three of these isolates (Lp 210, Lp 140 and Lp 19) presented suitable properties (fermentation at 45&deg;C, important acidification rate, enzymatic activities, osmotolerance, thermotolerance) necessary for their potential use in drastic environment. These rapid acid producers&rsquo; strains also induced a rapid drop of pH of MRS broth under pH 4 which is a major food safety factor. These potentialities confer to these strains ability to be selected as microbial starters for the reliable and reproducible lactic fermentation of cassava dough into attiek&eacute; in order to optimize and standardize the quality and organoleptic characteristics of this staple food. &nbsp; Key words: Attiek&eacute;, cassava, lactic acid bacteria, biochemical properties, lactic fermentation.

Evaluation of Bacteriophage Application to Cattle in Lairage at Beef Processing Plants to Reduce Escherichia coli O157:H7 Prevalence on Hides and Carcasses.

Escherichia coli O157:H7 is a major food safety concern for the beef industry. Several studies have provided evidence that cattle hides are the main source of beef carcass contamination during processing and that reductions in the E. coli O157:H7 load on the hides of cattle entering processing facilities will lead to reductions in carcass contamination. Bacteriophages have been proposed as a novel preharvest antimicrobial intervention to reduce the levels of E. coli O157:H7 on cattle hides. The objective of this study was to evaluate a commercialized phage application administered in the lairage area of commercial beef processing plants for the ability to reduce E. coli O157:H7 contamination of cattle hides and carcasses. Cattle lots either received phage spray treatment (n = 289) or did not (n = 301), as they entered the lairage environments in two separate experiments at two different commercial beef processing plants. Hide and carcass samples were collected and analyzed for E. coli O157:H7 prevalence and concentration. Cattle hides receiving phage treatment had an E. coli O157:H7 prevalence of 51.8%, whereas untreated hides had a prevalence of 57.6%. For carcass samples, the E. coli O157 prevalence in treated and untreated samples was 17.1% and 17.6%, respectively. The results obtained from these experiments demonstrated that the treatment of cattle hides with bacteriophages before processing did not produce a significant reduction of E. coli O157:H7 on cattle hides or beef carcasses during processing.