Flavus Growth Research Articles

Вивчення патологічної дії польового ізоляту Aspergillus Flavus на клінічний і біохімічний стан організму перепелів естонської породи

За результатами вивчення патологічної дії польового ізоляту A. flavus на організм перепелів доведено, що тривале згодовування контамінованого спорами корму викликає поступові (на 21- і 28-му добу) зміни клінічних і біохімічних показників птиці. Під час визначення коефіцієнтів маси внутрішніх органів перепелів встановлено зменшення відносної маси м’язового шлунку на 21-шу добу досліду у птиці І і ІІ дослідних груп та на 7-му добу після припинення згодовування контамінованого корму – І; ІІ та ІІІ груп (р<0,01; р<0,05) відповідно. Зареєстроване зменшення відносної маси печінки на 28-му добу в птиці ІІ дослідної групи та на 7-му добу після закінчення його згодовування – ІІІ групи (р<0,01; р<0,05) відповідно. При визначенні ступеня контамінації органів–мішеней встановлено, що кількість спор A. flavus у легенях, м’язовому шлунку та товстому кишечнику перепелів носить дозозалежний характер. Механізм патологічної дії A. flavus, спорами якого було штучно контаміновано корм, в організмі перепелів полягає у поступовому розвитку імуно- (лейкоцитоз, зниження гемоглобіну, надмірне утворення токсичних протеїнів – ЦІК і серомукоїдів поряд із гіперензимемією АлАТ; Р<0,05) і гепатотоксичних реакцій (підвищення рівня загальних протеїнів і креатиніну, гіпоензимемія АсАТ; Р<0,05), вираженість та незворотність яких залежить від кількості спор. Виявлені метаболічні зміни в організмі птиці були значно вираженими у випадку контамінації корму A. flavus у кількості ~ 300000 спор/г корму (ІІІ дослідна група), та не набували відновлення навіть через 7 діб після припинення його задавання.

Buckwheat Hull Extracts Inhibit Aspergillus flavus Growth and AFB1 Biosynthesis.

Fungal contamination poses at risk the whole food production chain - from farm to fork - with potential negative impact on human health. So far, the insurgence of pathogens has been restrained by the use of chemical compounds, whose residues have gradually accumulated determining toxic effects in the environment. Modern innovative techniques imply the use of natural and eco-sustainable bioactive plant molecules as pathogens and pests-control agents. These may be profitably recovered in large amounts at the end of industrial milling processes. This is the case of the non-digestible hull of common buckwheat (Fagopyrum esculentum Moench), a natural source of polyphenols, tocopherols, phytosterols and fatty acids. We extract these compounds from the hull of buckwheat; apply them to Aspergillus flavus - aflatoxin producer - under in vitro conditions, checking their ability to inhibit fungal growth and aflatoxin biosynthesis. Moreover, a solvent free method implying the adoption of supercritical CO2 as solvent was set up to extract lipophilic molecules from the buckwheat’ hulls. Positive results in controlling fungal growth and aflatoxin biosynthesis let infer that the extracts could be further tested also under in vivo conditions.

Biocontrol of Aspergillus flavus in Ensiled Sorghum by Water Kefir Microorganisms.

The capacity of microorganisms from water kefir (WK) to control Aspergillus flavus growth during the aerobic phase of ensiled sorghum grains was determined. Sorghum inoculated with A. flavus was treated with filter-sterilized and non-sterilized water kefir, ensiled, and incubated 7 days at 25 °C. A. flavus growth was quantified by qPCR after incubation. Mold growth was inhibited in the presence of water kefir while no inhibition was observed when filter-sterilized water kefir was applied, demonstrating the relevant role of the microorganisms in the kefir water in the biocontrol process. Fungal and bacterial diversity in treated sorghum mini-silos was analyzed by high-throughput sequencing. Firmicutes was the predominant bacterial phyla and Lactobacillus represented the most abundant genus, while Ascomycota was the predominant fungal phyla with Saccharomyces and Pichia as the major genera. Bacterial and yeast counts before and after incubation indicated that the microbial community obtained from WK was able to grow in the sorghum mini-silos in the presence of A. flavus. Results of the present work indicate that the use of a mixed inoculum of microorganisms present in WK may represent an alternative management practice to avoid the growth of A. flavus in ensiled sorghum grains and the concomitant contamination with aflatoxins.

EFFECT OF TEMPERATURES ON THE GROWTH OF FLORAL WASTE DEGRADING FUNGI

The goal of present study was to find out optimum growth temperature of isolated floral waste degrading fungi viz. Aspergillus fumigatus, Aspergillus flavus, Alternaria alternate and Aspergillus terreus. Eleven different temperature range ( 20°C, 22°C, 24°C, 26°C, 28°C, 30°C, 32°C, 34°C,36°C,38°C,40°C) were selected to find the optimum growth of these fungi on floral extract-basal medium for flask experiments. The optimum growth temperature of all four fungal strains was found at 32°C±1°C. Beside Alternaria alternate, remaining other three selected fungal strains showed growth at all selected temperatures. At optimum growth temperature (32°C±1°C), the highest growth occurred in Aspergillus fumigates and Aspergillus terreus (155 mg/50 ml/7 days) while lowest growth was observed in Aspergillus flavus and Alternaria alternata (140 mg/50 ml/7 days). At minimum selected growth temperature (20°C), maximum growth was found in Aspergillus flavus (45 mg/50 ml/7 days) and lowest growth occurred in Alternaria alternata (35 mg/50 ml/7 days) while at maximum selected growth temperature (40°C) highest growth seen in Aspergillus fumigatus and Aspergillus flavus (30 mg/50 ml/7 days) and no growth recorded in Alternaria alternata (00 mg/50 ml/7 days).

Use of lactic acid bacteria for the inhibition of Aspergillus flavus and Aspergillus carbonarius growth and mycotoxin production

Almonds and peanuts are a rich source of proteins, vitamins and unsaturated fatty acids. However, they can be also contaminated by mycotoxigenic fungi; a reason that has enhanced to investigate efficient strategies of management of these fungal contaminations. Some Lactic acid bacteria have been proven capable of inhibiting growth and mycotoxin production in livestock and transform it into nontoxic derivatives. In this work, four lactic acid bacteria (LAB) were tested for their abilities to inhibit the growth and mycotoxin production of Aspergillus flavus and Aspergillus carbonarius. Antifungal activity was evaluated in agar medium as well as in almonds and peanuts. Results showed that LAB significantly inhibited Aspergillus flavus and Aspergillus carbonarius in agar medium but none of the strains were able to completely inhibit fungal growth. The highest fungal growth inhibition was obtained using L. kefiri FR7 (51.67% and 45.56% growth inhibition of A. flavus and A. carbonarius, respectively). The cell-free supernatants (CFS) from LAB reduced fungal growth with average growth inhibitions ranging from 13.33% to 40.56% and 12.78% to 37.78% for A. flavus and A. carbonarius, respectively. We noted also that cell-free supernatants at pH7 (CFS-pH7) from the entire tested LAB did not inhibit fungal growth. L. kefiri FR7 was the most effective strain in mycotoxin suppression with a reduction percentage reaching 97.22%, 95.27% and 75.26% for AFB1, AFB2 and OTA respectively. Moreover, the inoculation of L. kefiri FR7 in almonds artificially contaminated with A. flavus decrease 85.27% of AFB1 and 83.94% of AFB2 content after 7 days of incubation. On the other hand, application of L. kefiri FR7 in peanuts artificially contaminated with A. carbonarius reduced OTA content to 25%. Our study revealed the potential use and application of L. kefiri FR7 in the control of fungi growth and mycotoxins production in almonds and peanuts.

Functional Analysis of Peptidyl-prolyl cis-trans Isomerase from Aspergillus flavus.

Aspergillus flavus, a ubiquitous filamentous fungus found in soil, plants and other substrates has been reported not only as a pathogen for plants, but also a carcinogen producing fungus for human. Peptidyl-Prolyl Isomerase (PPIases) plays an important role in cell process such as protein secretion cell cycle control and RNA processing. However, the function of PPIase has not yet been identified in A. flavus. In this study, the PPIases gene from A. flavus named ppci1 was cloned into expression vector and the protein was expressed in prokaryotic expression system. Activity of recombinant ppci1 protein was particularly inhibited by FK506, CsA and rapamycin. 3D-Homology model of ppci1 has been constructed with the template, based on 59.7% amino acid similarity. The homologous recombination method was used to construct the single ppci1 gene deletion strain Δppci1. We found that, the ppci1 gene plays important roles in A. flavus growth, conidiation, and sclerotia formation, all of which showed reduction in Δppci1 and increased in conidiation compared with the wild-type and complementary strains in A. flavus. Furthermore, aflatoxin and peanut seeds infection assays indicated that ppci1 contributes to virulence of A. flavus. Furthermore, we evaluated the effect of PPIase inhibitors on A. flavus growth, whereby these were used to treat wild-type strains. We found that the growths were inhibited under every inhibitor. All, these results may provide valuable information for designing inhibitors in the controlling infections of A. flavus.

Interaction of water activity and temperature on the growth, gene expression and aflatoxin production by Aspergillus flavus on paddy and polished rice

Water activity (aw) and temperature are two pivotal environmental factors affecting Aspergillus flavus growth and aflatoxin production. Here, we found that AFB1 production on polished rice can occur over a wider range of temperature × aw levels than that on paddies. For fungal growth on polished rice, the optimum conditions were aw 0.92–0.96 and 28–37 °C. The maximum amounts of AFB1 on polished rice was observed at 33 °C and aw 0.96. Compared to 33 °C, all tested genes of A. flavus on polished rice were significantly up-regulated at 25 °C under aw 0.96. The late structural genes of pathway were significantly down-regulated at 37 °C under aw 0.96, although aflR and aflS and most of early structural genes were up-regulated. Compared to aw 0.96, most of pathway genes were significantly down-regulated at aw 0.90 and 0.99 under 33 °C, although two regulatory genes were up-regulated at aw 0.90.

Biocontrol activity of volatile organic compounds from Streptomyces alboflavus TD-1 against Aspergillus flavus growth and aflatoxin production

Aspergillus flavus is a saprophytic fungus that contaminates crops with carcinogenic aflatoxin. In the present work, the antifungal effects of volatile organic compounds (VOCs) from Streptomyces alboflavus TD-1 against A. flavus were investigated. VOCs from 8-day-old wheat bran culture of S. alboflavus TD-1 displayed strong inhibitory effects against mycelial growth, sporulation, and conidial germination of A. flavus. Severely misshapen conidia and hyphae of A. flavus were observed by scanning electron microscopy after exposure to VOCs for 6 and 12 h, respectively. Rhodamine 123 staining of mitochondria indicated that mitochondria may be a legitimate antifungal target of the VOCs from S. alboflavus TD-1. Furthermore, the VOCs effectively inhibited aflatoxin B1 production by downregulating genes involved in aflatoxin biosynthesis. Dimethyl trisulfide and benzenamine may play important roles in the suppression of A. flavus growth and production of aflatoxin. The results indicate that VOCs from S. alboflavus TD-1 have tremendous potential to be developed as a useful bio-pesticide for controlling A. flavus.

Impact of nanoencapsulated natural bioactive phenolic metabolites on chitosan nanoparticles as aflatoxins inhibitor.

Aflatoxins are part of fungal secondary metabolites which become serious health, environmental, and economic problems and can cause corruption of many crops and agricultural grains that used as food and feed for human and animal. Aflatoxins mainly produce by Aspergillus spp. especially Aspergillus flavus and Aspergillus parasiticus. The present work aimed to study the effect of nanoencapsulation of chitosan (CS) nanoparticles with two phenolic compounds 1-(2-ethyl,6-heptyl)phenol (EHP) extracted from Cuminum cyminum and 5-ethyl-2-(methoxymethyl)phenol (EMMP) extracted from black pepper on growth and aflatoxins production of A. flavus and A. parasiticus. A. flavus growth was completely inhibited by 0.6 mg/ml of EHP and EMMP as well as A. parasiticus which showed the same minimal inhibition concentration with the first compound and 0.8 mg/ml with the second one. CS nanoparticles inhibited the growth of the tested organisms more than CS especially with A. parasiticus and this potency became much better when nanoencapsulated with the two extracted phenolic compounds. In inhibition of aflatoxins production, EHP reduced the production of aflatoxin B1 and B2 of A. flavus by 68.6% and 69.7%, respectively. In the same manner EMMP reduce the production of the two toxins by 87.3% and 82.6%, respectively. The reduction effect of CS nanoparticles is much more than that of CS as it record in most cases about twofold increase. Nanoencapsulation of CS nanoparticles by the extracted phenolic compounds is much more effective with complete inhibition of aflatoxin B1 of both fungi and aflatoxin G1 of A. parasiticus.

Essential oil of four medicinal plants and protective properties in plum fruits against the spoilage bacteria and fungi

There are limited studies available regarding the chemical composition of essential oils and their activities against fruit spoilage bacteria and fungi. In this study, chemical composition of essential oils from medicinal plants namely Acorus calamus, Allium sativum, Mucuna pruriens, and Sesamum indicum L showed invitro antibacterial and antifungal properties against fruits spoilage microbes were evaluated. Gas Chromatograph-Mass Spectrometry analysis confirmed the presence of major metabolites namely Hydroxylamine (98.26%), 1,2,4 - trimethoxy-5-1-propenyl (93.07%), Dodecanoic acid, 1,2,3-propanetriyl ester (92.64) and 2-diisoprophylphosphinnoethane (67.97%) from the studied plants. The minimum inhibitory concentration of the essential oils against bacteria were ranged from 11.3 ± 2.3 to 617 ± 4.9 μg/ml and fungi were ranged from 1.1 ± 0.4 to 292 ± 3.2 μg/ml, respectively. Among the essential oil, Allium sativum showed significant antibacterial activity with least minimum inhibitory concentration and minimum bactericidal concentrations (11.3 ± 2.3 μg/ml and 24 ± 1.6 μg/ml) while Sesamum indicum oil showed the least activity with high minimum inhibitory concentration and minimum bactericidal concentrations values (460 ± 11.9 μg/ml and 940 ± 12.8 μg/ml). Interestingly, Allium sativum documented the highest antifungal activity against Penicillium notatum and also significantly inhibited the growth of other tested fungal species such as, Aspergillus niger, Aspergillus flavus and Rhizopus microsporus. Among all tested essential oils, in combination of studied antibiotics, essential oils from Allium sativum showed excellent synergistic activity against seven out of nine spoilage microbes. Two-way analysis of variance showed significant depletion of pathogenic microorganism due to the effect of essential oils (p < 0.05). In addition, essential oil from Allium sativum significantly reduced the growth of Aspertillus flavus and Aspergillus niger on plum fruit. Results revealed the application of essential oil from Allium sativum counter Aspergillus flavus growth and prevented deterioration of plum fruit.

Inhibition of Aspergillus flavus Growth and Aflatoxin Production in Transgenic Maize Expressing the α-amylase Inhibitor from Lablab purpureus L.

Aflatoxin contamination in food and feed crops is a major challenge worldwide. Aflatoxins, produced by the fungus Aspergillus flavus (A. flavus) are potent carcinogens that substantially reduce crop value in maize and other oil rich crops like peanut besides posing serious threat to human and animal health. Different approaches, including traditional breeding, transgenic expression of resistance associated proteins, and RNA interference (RNAi)-based host-induced gene silencing of critical A. flavus gene targets, are being evaluated to increase aflatoxin resistance in susceptible crops. Past studies have shown an important role of α-amylase in A. flavus pathogenesis and aflatoxin production, suggesting this gene/enzyme is a potential target to reduce both A. flavus growth and aflatoxin production. In this regard, the current study was undertaken to evaluate heterologous expression (under control of the constitutive CaMV 35S promoter) of a Lablab purpureus L. α-amylase inhibitor-like protein (AILP) in maize against A. flavus. AILP is a 36-kDa protein, which is a competitive inhibitor of A. flavus α-amylase enzyme and belongs to the lectin-arcelin-α-amylase inhibitor protein family in common bean. In vitro studies prior to the current work had demonstrated the role of AILP in inhibition of A. flavus α-amylase activity and fungal growth. Fungal growth and aflatoxin production in mature kernels were monitored in real time using a GFP-expressing A. flavus strain. This kernel screening assay (KSA) is very simple to set up and provides reliable and reproducible data on infection and the extent of spread that could be quantified for evaluation of germplasm and transgenic lines. The fluorescence from the GFP strain is closely correlated to fungal growth and, by extension, it is well-correlated to aflatoxin values. The goal of the current work was to implement this previous knowledge in a commercially important crop like maize to increase aflatoxin resistance. Our results show a 35%-72% reduction in A. flavus growth in AILP-expressing transgenic maize kernels which, in turn, translated into a 62%-88% reduction in aflatoxin levels.

The action mechanism and biocontrol potentiality of novel isolates of Saccharomyces cerevisiae against the aflatoxigenic Aspergillus flavus.

Inhibition of Aspergillus flavus growth and its aflatoxins production using the biocontrol agent Saccharomyces cerevisiae as well as to explore its mode of action was studied. Eight strains of S. cerevisiae strains were able to suppress the growth of A. flavus Z103. The maximum growth inhibition of A. flavus Z103 was obtained by living cells of S. cerevisiae EBF101 and S. cerevisiae 117 with 85 and 83%, respectively. The sporulation inhibition and hyphae deterioration of A. flavus Z103 by S. cerevisiae cells adhesion were observed under SEM; up to 99·8% inhibition of aflatoxins biosynthesis by A. flavus Z103 was resulted when the fungus was treated by autoclaved extracellular crude of S. cerevisiae. Also, the tested strains are potential to produce exo-chitinase which could be suggested as another mode of action for its antifungal activity. GC-MS analysis of S. cerevisiae 117 extracellular secondary metabolites revealed the existence of 4-Hydroxyphenethyl alcohol (46·32%), 4, 4-Dimethyloxazole (9·14%) and 1,2-Benzenedicarboxylic acid dioctyl ester (2·8%). Significance and Impact of the Study: The use of Saccharomyces cerevisiae instead of chemical preservatives in fermented food, animal and fish feed and storage cereal grains could encourage the food industry to produce organic food free of chemical additives. Overall, our data suggest the possibility of using S. cerevisiae as an alternative treatment in the food industries to control the dispersion and aflatoxins production by Aspergillus flavus during storage. This method could provide an additional probiotic effect in the digestive tract of consumers after ingestion of the treated food. So, our study clarifies the exact mechanisms responsible for the reduction of the aflatoxin contents by S. cerevisiae.

Chemical Composition and Antifungal Activity of Essential Oil of Zataria Multiflora

Background: Aspergillus flavus is a toxic contaminant in foods, which can induce mutagenic, teratogenic, and carcinogenic effects. In last decades, synthetic fungicides have been used for inhibition of fungal growth in plants. The public attention was also attracted to contamination of food chain by these chemicals. Therefore, in the current study, we decided to use Zataria multiflora (ZM) essential oil to inhibit the Aspergillus flavus growth. Method: The essential oil from ZM was obtained by hydro-distillation and analyzed by GC/MS. The minimal inhibitory concentration (MIC) and minimal fungicidal concentration (MFC) of ZM essential oil were determined at different concentrations (0-1000 ppm). Results: In this study, Carvacrol (33.45%) and Thymol (34.44%) were the most frequent compounds of the ZM essential oil. The minimum inhibitory and fungicidal concentrations were 100 and 400 ppm, respectively. Conclusions: The presence of phenolic compounds such as Thymol and Carvacrol, as the major components of ZM essential oil inhibits the Aspergillus flavus growth. Furthermore, this essential oil has a very strong anti-bacterial effect. Considering these results, it seems that ZM essential oil is potentially an appropriate natural alternative for controlling Aspergillus flavus fungus.

Purification and characterization of two grandiuvarones from Desmos chinensis leaves and their antimicrobial activities

A novel aromatic compound, grandiuvarone B (5-acetoxy-3-benzoyloxymethyl-5H-oxepin-4-one), along with a known compound grandiuvarone A (5-acetoxy-6-benzoyloxymethyl-5H-oxepin-4-one) were isolated from methanol extracts of Desmos chinensis leaves. Their structures were determined by various spectroscopic techniques including nuclear magnetic resonance (NMR), high-resolution electrospray ionisation mass spectrometry (HR-ESI-MS) and circular dichroism (CD). Grandiuvarone A and grandiuvarone B are isomers and the S configuration of grandiuvarone B was reported for the first time. We then determined their antifungal activity against Aspergillus flavus. Results revealed that grandiuvarone B exhibited better antifungal activity against A. flavus, with MIC values of 0.01 mg/mL compared to grandiuvarone A (MIC values of 0.02 mg/mL). In the presence of each active compound at 160 μg/g of aquafeed, A. flavus growth was completely inhibited. Grandiuvarone B also showed antibacterial activity against the plant pathogen Ralstonia solanacearum.

Antifungal activities of coating incorporated with Saccharomyces cerevisiae cell wall mannoprotein on Aspergillus flavus growth and aflatoxin production in pistachio (Pistacia vera L.)

AbstractIn this study, the effects of the mannoprotein isolated from Saccharomyces cerevisiae (ScMnn) were evaluated against Aspergillus flavus growth and aflatoxin (AF) production in pistachios. The mannoprotein extracted from the cell wall of S. cerevisiae was incorporated in gelatin‐based solution at different concentration (0, 0.5, 1 and 1.5% w/w) then used as coating of kernels. A. flavus spore suspension (104 spores/mL) was inoculated on both coated (cp) and non‐coated (ncp) pistachios. In cp samples, the mycelium development was delayed and AF content decreased, compared with the ncp ones. Noteworthy, the coating containing 1.5% ScMnn decreased AFB1 up to 42.81%. The ScMnn could be considered as an operative agent to reduce A. flavus growth and AF contamination in pistachios. The edible and food grade properties are important in its application as novel additive and as bioactive agent in coatings for the control of AF in pistachios.Practical applicationsActive edible coating containing Saccharomyces cerevisiae mannoprotein could be applied in pistachio industry to control Aspergillus flavus growth and reduce aflatoxin contamination. This antifungal coating could improve the safety of pistachio nuts.

Chestnut Drying Is Critical in Determining Aspergillus flavus Growth and Aflatoxin Contamination.

Chestnut drying is used to prevent postharvest losses and microorganism contamination during storage. Several studies reported the contamination by aflatoxins (AFs) produced by Aspergillus spp. in chestnuts. The effect of drying temperatures (from 30 to 50 °C) was evaluated on the growth of A. flavus and the production of aflatoxins in chestnuts. The influence of the treatment on the proximate composition, the total phenol content and antioxidant activity of chestnuts was considered. Fungal colonization was observed on the nuts dried at 30, 35, and 40 °C; the incidence was lower at 40 °C. The highest concentrations of AFB1 and AFB2 were produced at 40 °C. No aflatoxins were detected at 45 or 50 °C. At 40 °C A. flavus was under suboptimal conditions for growth (aw 0.78), but the fungus was able to synthesize aflatoxins. As the temperatures applied increased, the total phenol content increased, while the antioxidant activity decreased. A drying treatment at 45 °C for seven days (aw 0.64) could be a promising method to effectively control both the growth of aflatoxigenic fungi and the production of aflatoxins. This study provides preliminary data useful to improve the current drying conditions used in chestnut mills, to reduce both fungal growth and aflatoxin production.

Controlling aflatoxin contamination and propagation of Aspergillus flavus by a soy-fermenting Aspergillus oryzae strain

Aflatoxins (AFs) are a group of carcinogenic and immunosuppressive mycotoxins that threaten global food safety. Globally, over 4.5 billion people are exposed to unmonitored levels of AFs. Aspergillus flavus is the major source of AF contamination in agricultural crops. One approach to reduce levels of AFs in agricultural commodities is to apply a non-aflatoxigenic competitor, e.g., Afla-Guard, to crop fields. In this study, we demonstrate that the food fermenting Aspergillus oryzae M2040 strain, isolated from Korean Meju (a brick of dry-fermented soybeans), can inhibit aflatoxin B1 (AFB1) production and proliferation of toxigenic A. flavus in lab culture conditions and peanuts. In peanuts, 1% inoculation level of A. oryzae M2040 could effectively displace the toxigenic A. flavus and inhibit AFB1 production. Moreover, cell-free culture filtrate of A. oryzae M2040 effectively inhibited AFB1 production and A. flavus growth, suggesting A. oryzae M2040 secretes inhibitory compounds. Whole genome-based comparative analyses indicate that the A. oryzae M2040 and Afla-Guard genomes are 37.9 and 36.4 Mbp, respectively, with each genome containing ~100 lineage specific genes. Our study establishes the idea of using A. oryzae and/or its cell-free culture fermentate as a potent biocontrol agent to control A. flavus propagation and AF contamination.

Isolation and identification of novel antioxidant and antimicrobial oligopeptides from enzymatically hydrolyzed anchovy fish meal

Abstract Natural Antioxidants and antimicrobials are preferred to prolong food shelf life, therefore we isolated and identified novel natural antioxidant and antimicrobial oligopeptides from anchovy fish meal hydrolysate. Firstly, the oligopeptide mixture was prepared by two-step hydrolysis using alkaline and neutral proteases step by step for enriching oligopeptides. Then, four novel oligopeptide fractions were purified using reversed phase-high performance liquid chromatography, and their sequences were determined using high performance liquid chromatography-time of flight-mass spectrometry. Meanwhile, antioxidant and antimicrobial activities of the fractions were evaluated. Thr-Pro-Ser-Ala-Gly-Lys exhibited the highest hydroxyl scavenging activity, lipid peroxidation inhibition, ferrous ion chelating activity as well as Escherichia coli growth inhibition. Thr-Pro-Ser-Asn-Leu-Gly-Gly-Lys showed the highest superoxide scavenging activity, lipid peroxidation inhibition, and Staphylococcus aureus growth inhibition. Leu-Glu and Leu-Glu-Glu displayed similarly high inhibition activity on 2,2′-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid. Almost no suppression effects on Aspergillus flavus and Candida albicans growth were observed for all isolated fractions. These results indicate that the oligopeptide mixture derived from anchovy fish meal could serve as a suitable source of antioxidant and antimicrobial oligopeptides.

Effect of Extracts of Capparis spinosa, Withania somnifera and Peganum harmala on Aspergillus flavus Growth and Expression of Major Genes in Aflatoxin Biosynthetic Pathway

Background: Aflatoxins, a polyketide group derived from furanocoumarins, are highly toxic carcinogens produced by Aspergillus flavus and other closely related species. Objectives: In this research, the effects of Capparis spinosa, Withania somnifera, and Peganum harmala extracts on A. flavus growth and the expression of some major genes in aflatoxin biosynthetic pathway were investigated. Methods: Minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) were measured and the expression of aflQ, aflO, aflS, and aflR genes was evaluated by using quantitative real-time polymerase chain reaction (qRT-PCR) technique. Results: Capparis spinosa extract had the lowest MIC value (200 mg/mL) and the extracts of W. somnifera and P. harmala had the highest MIC value (400 mg/mL). The extracts of W. somnifera and P. harmala had no fungicidal activity, and the C. spinosa extract had the lowest MFC value (400 mg/mL) and had the highest fungicidal effect on A. flavus. The expression of aflQ, aflO, aflS, and aflR genes was significantly decreased by the C. spinosa extract. Conclusions: In general, the C. spinosa extract could have fungicidal and inhibitory effects on A. flavus and reduce expression of major genes in the aflatoxin biosynthetic pathway.

Effective chemical management for prevention of aflatoxins in maize

The presence of aflatoxins in maize grain has been an increasing problem in the Mediterranean area, possibly due to climate change such as increased temperatures and extended drought periods. It is therefore important to prevent the growth of aflatoxigenic Aspergillus species in the field. There are no fungicides registered for control A. flavus in maize, so this study investigated the efficacy of azoxystrobin, boscalid, cyprodinil, fludioxonil and cyprodinil + fludioxonil to reduce A. flavus growth, sporulation and aflatoxin production in in vitro , and in maize field studies. Based on in vitro inhibition of mycelial growth, the most effective fungicides were cyprodinil (EC 50 0.5 μg mL -1 . Further evaluation of the fungicides on maize seeds infected with A. flavus demonstrated that all the fungicides reduced conidium production by 76 to 94%, and reduced aflatoxin contamination. In a 2-year field study, application of cyprodinil + fludioxonil reduced A. flavus ear rot severity by 40%, and was the most effective formulation for reducing aflatoxin contamination, by 83%. The other four single ingredient fungicides also decreased aflatoxin production on maize kernels (fludioxonil by 80%, cyprodinil by 75%, boscalid by 74% and azoxystrobin by 67%). Field data from this study provide farmers with a new effective chemical approach to control A. flavus and aflatoxin production in maize within an integrated strategy for management of aflatoxins in maize.