Antifungal and antiaflatoxigenic assessment of new Cu(II)-pq complexes against Aspergillus parasiticus, in dark conditions and under visible irradiation.

The issue of food contamination by fungi and aflatoxins; constitutes a serious concern not only for human/animal health but also for agriculture and the economy. Aflatoxins are secondary metabolites produced by certain filamentous fungi and contaminate a variety of foodstuffs. In this context, control of fungal growth and aflatoxin contamination appears to be important. The present study aimed to investigate new Cu(I) and Cu(II)-quinoxaline complexes, namely [Cu(2,2´-pq)(NO3)](NO3) (1), [Cu(2,2´-pq)2(NO3)](NO3)·6H2O (2) and [Cu(2,2΄-pq)2](BF4) (3), where 2,2´-pq is 2-(2'-pyridyl quinoxaline), as antifungal agents against Aspergillus parasiticus. All complexes, the ligand and the starting material Cu(NO3)2-3H2O, regardless of the concentration used, caused inhibition of A. parasiticus growth ranged from 8.52 to 33.33%. The fungal growth inhibition was triggered when irradiation in visible (λ > 400 nm) was continuously applied (range 18.36-57.20%). The highest inhibitory activity was exhibited by the complex [Cu(2,2´-pq)2(NO3)](NO3)·6H2O and for this reason, it was selected to be studied for its ability to suppress aflatoxin B1 produced by A. parasiticus. AFB1 production after the irradiation process was found to be suppressed by 25% compared to AFB1 produced in dark conditions.

Inclusion of a phytogenic bend in broiler diet as a performance enhancer and anti-aflatoxin agent: Impacts on health, performance, and meat quality.

The objective of this study was to determine whether a phytogenic blend (PB), formulated based on organic acids, tannins, curcumin, and essential oils, could replace the antimicrobials commonly used as growth promoters in the poultry industry without compromising zootechnical performance, health, or meat quality. In addition, our goal was to report the anti-aflatoxin effect of this phytogenic blend. Four treatments were used: TC, or control; T250, T500, and T1000, representing test doses of 250, 500, 1000 mg PB/kg of feed, respectively, or a 34-day experiment (initial and growth phases). On day 22 of the study and age of the birds, 500 ppb of aflatoxin was included in the diet to represent an intestinal challenge and to evaluate the growth-promoting effects of PB. In the initial phase (up to 21 days), there were no differences between groups in weight gain, feed intake, or feed conversion. After adding an aflatoxin-contaminated feed, doses of 250 and 500 mg/kg minimized the adverse effects on feed consumption and feed conversion caused by aflatoxin; but 1000 mg/kg did not differ between groups. In birds that consumed PB (T250, T500, and T1000) compared to the control, there were the following changes: 1) lower counts of heterophiles, lymphocytes, and monocytes; 2) lower lipid peroxidation and high non-protein thiols levels in breast meat; 3) lower bacteria counts in broiler litter; and 4) lower ALT levels. Greater intestinal villus/crypt ratios were observed at T250 and T500. The dose of 250 mg/kg reduced saturated fatty acids and increased unsaturated fatty acids. The chemical-physical composition of the meat did not differ between treatments. The findings suggest that the addition of a PB has a high potential to improve performance for chickens in the growing stage and minimize the adverse effects of aflatoxicosis.

Dioctatin Activates ClpP to Degrade Mitochondrial Components and Inhibits Aflatoxin Production.

Aflatoxin contamination of crops is a serious problem worldwide. Utilization of aflatoxin production inhibitors is attractive, as the elucidation of their modes of action contributes to clarifying the mechanism of aflatoxin production. Here, we identified mitochondrial protease ClpP as the target of dioctatin, an inhibitor of aflatoxin production of Aspergillus flavus. Dioctatin conferred uncontrolled caseinolytic capacity on ClpP of A. flavus and Escherichia coli. Dioctatin-bound ClpP selectively degraded mitochondrial energy-related proteins in vitro, including a subunit of respiratory chain complex V, which was also reduced by dioctatin in a ClpP-dependent manner in vivo. Dioctatin enhanced glycolysis and alcohol fermentation while reducing tricarboxylic acid cycle metabolites. These disturbances were accompanied by reduced histone acetylation and reduced expression of aflatoxin biosynthetic genes. Our results suggest that dioctatin inhibits aflatoxin production by inducing ClpP-mediated degradation of mitochondrial energy-related components, and that mitochondrial energy metabolism functions as a key determinant of aflatoxin production.

GC-EIMS analysis, antifungal and anti-aflatoxigenic activity of Capsicum chinense and Piper nigrum fruits and their bioactive compounds capsaicin and piperine upon Aspergillus parasiticus.

GC-EIMS analysis, antifungal- and anti-aflatoxigenic activities of the ethanolic extract of Capsicum chinense and Piper nigrum fruits and their main bioactive compounds were evaluated upon Aspergillus parasiticus. The GC-EIMS analysis showed capsaicin (50.49%) and piperine (95.94%) as the major constituents in C. chinense and P. nigrum, respectively. MIC50 values revealed that capsaicin (39 µg/mL) and piperine (67 µg/mL) were lower than those from fruit extracts of C. chinense (381 µg/mL) and P. nigrum (68 µg/mL). Extracts and bioactive compounds showed anti-aflatoxigenic activity. Maximum aflatoxin inhibition occurred at 150 µg/mL of extracts and compounds. The present study showed satisfactory results concerning the effects of ethanolic extract of C. chinense and P. nigrum fruits upon A. parasiticus, showing the capabilities of inhibiting fungal growth development and altering aflatoxins production.

Assessment of chemically characterised Myristica fragrans essential oil against fungi contaminating stored scented rice and its mode of action as novel aflatoxin inhibitor.

The study reports chemically characterised Myristica fragrans essential oil (MFEO) as plant based food preservative against fungal and aflatoxin B1 (AFB1) contamination of scented rice varieties. The chemical profile of MFEO revealed elemicin (27.08%), myristicine (21.29%) and thujanol (18.55%) as major components. The minimum inhibitory and minimum aflatoxin inhibitory concentrations of MFEO were 2.75 and 1.5 mg/ml, respectively. The MFEO was efficacious against a broad spectrum of food deteriorating fungi. MFEO caused decrease in ergosterol content of fungal plasma membrane and enhanced leakage of cellular ions, depicting plasma membrane as the site of action. The MFEO caused reduction in cellular methylglyoxal content, the aflatoxin inducer. This is the first report on MFEO as aflatoxin suppressor. The essential oil may be recommended as plant based food preservative after large scale trials and reduction in methylglyoxal suggests its application for development of aflatoxin resistant varieties through green transgenics.

Fabrication, characterization and practical efficacy of Myristica fragrans essential oil nanoemulsion delivery system against postharvest biodeterioration.

The present study deals with encapsulation of Myristica fragrans essential oil (MFEO) into chitosan nano-matrix, their characterization and assessment of antimicrobial activity, aflatoxin inhibitory potential, safety profiling and in situ efficacy in stored rice as environment friendly effective preservative to control the postharvest losses of food commodities under storage. Surface morphology of MFEO-chitosan nanoemulsion as well as encapsulation of MFEO was confirmed through SEM, FTIR and XRD analysis. In vitro release characteristics with biphasic burst explained controlled volatilization from nanoencapsulated MFEO. Unencapsulated MFEO exhibited fungitoxicity against 15 food borne molds and inhibited aflatoxin B1 secretion by toxigenic Aspergillus flavus LHP R14 strain. In contrast, nanoencapsulated MFEO showed better fungitoxicity and inhibitory effect on aflatoxin biosynthesis at lower doses. In situ efficacy of unencapsulated and nanoencapsulated MFEO on stored rice seeds exhibited effective protection against fungal infestation, aflatoxin B1 contamination, and lipid peroxidation. Both the unencapsulated and nanoencapsulated MFEO did not affect the germination of stored rice seeds confirming non-phytotoxic nature. In addition, negligible mammalian toxicity of unencapsulated MFEO (LD50 = 14,289.32 µL/kg body weight) and MFEO loaded chitosan nanoemulsion (LD50 = 9231.89 µL/kg body weight) as revealed through favorable safety profile recommend the industrial significance of nanoencapsulated MFEO as an effective green alternative to environmentally hazardous synthetic pesticides for protection of food commodities during storage.

Antifungal and antiaflatoxigenic activity of rosemary essential oil (Rosmarinus officinalis L.) against Aspergillus flavus.

The increased risk to health by diverse pathologies, such as cancer, liver diseases, and endocrine alterations, caused by chemical residues in food, has led to the search for sustainable agricultural management alternatives, such as the use of essential oils for the development of natural and eco-friendly fungicides. The aim of this study was to evaluate the antifungal and antiaflatoxigenic activity of Rosmarinus officinalis L. essential oil (REO) against Aspergillus flavus Link. REO was obtained by hydrodistillation and its major components were identified as 1,8-cineole (eucalyptol, 52.2%), camphor (15.2%) and α-pinene (12.4%) by GC/MS and NMR. The minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) were both 500 µg/mL. REO reduced the mycelial growth of A. flavus at a concentration of 250 µg/mL (15.3%). The results obtained from scanning electron microscopy (SEM) demonstrated a reduction in the size of conidiophores and in the thickness of hyphae in A. flavus caused by treatment with REO (250 µg/mL). The production of ergosterol and the biomass of mycelium were both reduced as the REO treatment concentration increased. The production of aflatoxins B1 and B2 was inhibited after treatment with 250 µg/mL REO, a concentration below the MIC/MFC, indicating that the antiaflatoxigenic effect of REO is independent of its antifungal effect and is likely due to its direct action upon toxin biosynthesis. The data demonstrated that REO may be used as an alternative to synthetic fungicides.

Comparison of the Antifungal and Antiaflatoxigenic Potential of Liquid and Vapor Phase of Thymus vulgaris Essential Oil against Aspergillus flavus.

The antifungal and antiaflatoxigenic activity of Thymus vulgaris essential oil (EO) against Aspergillus flavus was evaluated over a range of concentrations in vapor- and liquid-phase contact tests. Total reduction in mycelial growth in the vapor- and liquid-phase tests was detected at EO concentrations of 20 and 400 µg/mL, respectively. Treatment with 10 µg/mL EO reduced aflatoxin production by 97.0 and 56.4% in the vapor- and liquid-phase tests, respectively. Greater inhibition of the expression of both fungal development-related genes (brlA, abaA, and wetA) and aflatoxin biosynthesis-related genes (aflR, aflD, and aflK) was also observed in the vapor-phase test. A substantial reduction in aflatoxin production was also observed in brown rice (72.7%) and white rice (18.0%). Our results indicate that the way this EO contacts fungal cells significantly affects its antifungal activity and that T. vulgaris EO in vapor phase might be a good strategy to control fungal contamination.

Antimicrobial activity, antiaflatoxigenic potential and in situ efficacy of novel formulation comprising of Apium graveolens essential oil and its major component.

The present study reports the formulation of Apium graveolens essential oil (AGEO) with its major components linalyl acetate (LA) and geranyl acetate (GA) (1:1:1) as a novel green preservative for protection of postharvest food commodities from fungal infestations, aflatoxin B1 (AFB1) secretion, free radical generation and lipid peroxidation. The essential oil based novel formulation displayed considerable inhibitory action against fourteen food borne molds responsible for deterioration of stored food commodities, in addition to the most toxigenic strain of Aspergillus flavus (AFLHPR14) isolated from fungal and aflatoxin contaminated rice seeds. The observed higher efficacy of designed formulation was due to the synergistic action of essential oil and its major components. Fungal plasma membrane was recorded as the possible target site of antifungal action of the formulation as revealed through reduction in membrane ergosterol content, increased intracellular propidium iodide (PI) fluorescence and enhanced leakage of cellular ions (sodium, potassium, calcium) and 260, 280 nm absorbing materials. Further, inhibition of methylglyoxal (an aflatoxin inducer) confirmed the aflatoxin inhibitory potential of novel formulation based on essential oil and its major components. High antioxidant potential as observed through DPPH and ABTS·+ radical scavenging assay, improved phenolic content, considerable inhibition of lipid peroxidation in stored rice seeds, in situ efficacy on AFB1 inhibition in food system under storage container system, acceptable sensorial characteristics and favorable safety profile during animal trials suggest the recommendation of the designed formulation for large scale application as green preservative by food and agriculture based industries against fungal and aflatoxin contamination of stored commodities.

Sabotage at the Powerhouse? Unraveling the Molecular Target of 2-Isopropylbenzaldehyde Thiosemicarbazone, a Specific Inhibitor of Aflatoxin Biosynthesis and Sclerotia Development in Aspergillus flavus, Using Yeast as a Model System.

Amongst the various approaches to contain aflatoxin contamination of feed and food commodities, the use of inhibitors of fungal growth and/or toxin biosynthesis is showing great promise for the implementation or the replacement of conventional pesticide-based strategies. Several inhibition mechanisms were found taking place at different levels in the biology of the aflatoxin-producing fungal species such as Aspergillus flavus: compounds that influence aflatoxin production may block the biosynthetic pathway through the direct control of genes belonging to the aflatoxin gene cluster, or interfere with one or more of the several steps involved in the aflatoxin metabolism upstream. Recent findings pointed to mitochondrial functionality as one of the potential targets of some aflatoxin inhibitors. Additionally, we have recently reported that the effect of a compound belonging to the class of thiosemicarbazones might be related to the energy generation/carbon flow and redox homeostasis control by the fungal cell. Here, we report our investigation about a putative molecular target of the 3-isopropylbenzaldehyde thiosemicarbazone (mHtcum), using the yeast Saccharomyces cerevisiae as model system, to demonstrate how the compound can actually interfere with the mitochondrial respiratory chain.

Técnicas de descontaminação de castanhas-do-brasil intencionalmente contaminadas com Aspergillus nomius / Techniques of decontamination of brazil nuts intentionally contaminated with Aspergillus nomius

A castanha-do-brasil é uma matéria-prima de origem amazônica, conhecida por seus benefícios nutricionais. Entretanto, por conta da produção extrativista este produto está susceptivel a vários focos de contaminação durante a cadeia produtiva. Este trabalho teve como objetivos a avaliação de diferentes métodos de descontaminação para controle de Aspergillus nomius produtor de aflatoxinas em castanha-do-brasil. As amostras de castanhas foram inoculadas com suspensão de A. nomius e posteriormente, foram testadas as técnicas de secagem em estufa a 60°C por 8 horas, esterilização em cabine UV por 20 minutos e sanitização com hipoclorito de sódio a 200 ppm por 15 minutos. Todos os tratamentos tiveram ação sob a cepa, sendo obtidos reduções de 3,18; 1,66 e 1,04 RD, respectivamente. A secagem mostrou-se o melhor tratamento de descontaminação, no entanto, mais pesquisas com outros métodos de descontaminação em castanhas são necessárias para controle da contaminação fúngica.

Size and coating of engineered silver nanoparticles determine their ability to growth-independently inhibit aflatoxin biosynthesis in Aspergillus parasiticus.

Recent studies from our laboratory indicate that engineered silver nanoparticles can inhibit aflatoxin biosynthesis even at concentrations at which they do not demonstrate antifungal activities on the aflatoxin-producing fungus. Whether such inhibition can be modified by altering the nanoparticles' physical properties remains unclear. In this study, we demonstrate that three differently sized citrated-coated silver nanoparticles denoted here as NP1, NP2, and NP3 (where, sizes of NP1 < NP2 < NP3) inhibit aflatoxin biosynthesis at different effective doses in Aspergillus parasiticus, the plant pathogenic filamentous fungus. Recapping NP2 with polyvinylpyrrolidone coating (denoted here as NP2p) also altered its ability to inhibit aflatoxin production. Dose-response experiments with NP concentrations ranging from 10 to 100 ng mL-1 indicated a non-monotonic relationship between aflatoxin inhibition and NP concentration. The maximum inhibitory concentrations differed between the NP types. NP1 demonstrated maximum inhibition at 25 ng mL-1. Both NP2 and NP3 showed maximum inhibition at 50 ng mL-1, although NP2 resulted in a significantly higher inhibition than NP3. While both NP2 and NP2p demonstrated greater aflatoxin inhibition than NP1 and NP3, NP2p inhibited aflatoxin over a significantly wider concentration range as compared to NP2. Our results, therefore, suggest that nano-fungal interactions can be regulated by altering certain NP physical properties. This concept can be used to design NPs for mycotoxin prevention optimally.

Preparation, characterization and anti-aflatoxigenic activity of chitosan packaging films incorporated with turmeric essential oil.

Here, we studied the preparation, characterization, anti-aflatoxigenic activity, and molecular mechanism in vitro of chitosan packaging films containing turmeric essential oil (TEO). First, we took the mechanical properties as the evaluation Index, screened for the optimum preparation conditions of packaging films with 1.5 µL/cm2 TEO using single factor and orthogonal experiments, and characterized the film properties. We found that the addition of TEO affected the microcosmic structure of films and advanced water resistance capacity. In addition, we investigated the inhibitory effects of pure chitosan films and packaging films containing 1.5 µL/cm2 or 3.0 µL/cm2 TEO on the growth and conidial formation of Aspergillus flavus (A. flavus, CGMCC 3.4410), as well as the accumulation of aflatoxin over the course of seven days. We found that the packaging films possessed a prominent antifungal activity on A. flavus. Finally, we discuss preliminary results surrounding gene expression of packaging films which inhibit aflatoxin biosynthesis. The expressions levels of 16 genes related to aflatoxin biosynthesis were found to be either completely or almost completely inhibited. Therefore, the addition of the natural antifungal agent TEO in chitosan packaging films represent a remarkable method to significantly promote the development and application of antifungal packaging materials.

Isolation of a novel deep-sea Bacillus circulus strain and uniform design for optimization of its anti-aflatoxigenic bioactive metabolites production.

The deep-sea bacterium strain FA13 was isolated from the sediment of the South Atlantic Ocean and identified as Bacillus circulans based on 16S ribosomal DNA sequence. Through liquid fermentation with five media, the cell-free supernatant fermented with ISP2 showed the highest inhibition activities against mycelial growth of Aspergillus parasiticus mutant strain NFRI-95 and accumulation of norsolorinic acid, a precursor for aflatoxin production. Based on ISP2, uniform design was used to optimize medium formula and fermentation conditions. After optimization, the inhibition efficacy of the 20-time diluted supernatant against A. parasiticus NFRI-95 mycelial growth and aflatoxin production was increased from 0-23.1% to 100%. Moreover, compared to the original protocol, medium cost and fermentation temperature were significantly reduced, and dependence on seawater was completely relieved, thus preventing the fermentor from corrosion. This is the first report of a deep-sea microorganism which can inhibit A. parasiticus NFRI-95 mycelial growth and aflatoxin production.

Antiaflatoxigenic effects of selected antifungal peptides.

Aflatoxins are potent carcinogenic mycotoxins produced as secondary metabolites mainly by the fungi Aspergillus flavus and Aspergillus parasiticus. Control measures to curtail the contamination of aflatoxin in food products is still a challenge. Although there are several reports on the antifungal peptides, there is no specific study on the action of antifungal peptides on aflatoxin synthesis. This work details the effect of four antimicrobial peptides (AMPs) - PPD1 (FRLHF), 66-10 (FRLKFH), 77-3 (FRLKFHF) and D4E1 (FKLRAKIKVRLRAKIKL) on the aflatoxin production by A. flavus and A. parasiticus. Results of the investigations suggests that AMPs at near minimum inhibitory concentrations (MIC) were effectively inhibiting aflatoxins, without hindering the growth of the fungi. These AMPs, at concentrations near MIC, induced membrane permeabilisation, without inducing cellular leakage. The involvement of oxidative stress for the aflatoxin synthesis was reversed by the antioxidant nature of the peptides as evidenced by the 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid (ABTS) assay, reactive oxygen species production, malondialdehyde and antioxidant enzymes analysis. Quantitative real time polymerase chain reaction (RT-qPCR) analysis of the aflatoxin gene cluster showed that 'aflR' and its downstream genes expressions were significantly down regulated. Conidiation of the fungi were negatively influenced by the peptides as evidenced by scanning electron microscopy analysis and RT-qPCR. mRNA levels of Manganese-superoxide dismutase (Mn-SOD) showed a decrease in the expression in RT-qPCR. The effect of these peptides on aflatoxin inhibition provides insight into their use as novel antiaflatoxigenic molecules.

Antifungal and anti-aflatoxin efficacy of biogenic silver nanoparticles produced by Aspergillus species: Molecular study.

Date palm (Phoenix dactylifera L.) is considered the main crop in deserts and arid areas such as Saudi Arabia. Fifteen species belonging to 7 fungal genera were isolated from date palm rhizosphere soil at Riyadh, Saudi Arabia. Twenty-one isolates of Aspergillus spp. were used in producing silver nanoparticles (SNPs), five of A. flavus, nine of A. niger and seven of A. terreus. Synthesis of SNPs by these fungi is emerging as an important branch of nanotechnology due to it'secofriendly, safe and cost-effective nature. SNPs have been characterized by UV-Visible Spectrophotometer and Transmission Electron Microscope (TEM). In order to increase the yield of biosynthesized SNPs of desired shape and size, it is necessary to control the cultural and physical parameters during the synthesis. We reported the optimum synthesis of SNPs on a liquid medium at 1.5mM of silver nitrate, pH 9 and 26°C after 96 hours. Antifungal activity of SNPs colloids has indicated that the highest inhibition zone was detected with SNPs. In the case of SNPs synthesized by A. terreus PNU37, the highest Inhibition percentage (IP %) 67.6% at the concentration 150 ppm of SNPs. Results have also indicated that the SNPs synthesized by A. flavus PNU05 at a concentration of 150 ppm/100 ml culture medium gave the highest reduction of B1 determined by HPLC, where the percentages of reduction (PR%) was 56.45%.ISSR analysis revealed a high level of genetic diversity in the Aspergillus spp. population and useful for genetic characterization. ISSR markers were not suitable to discriminate between producing and non-producing SNPs isolates. There was no clear-cut relationship between the ISSR markers (genotype of isolates), antifungal and anti-aflatoxigenic properties.

Anti-aflatoxigenic effect of organic acids produced by Lactobacillus plantarum.

Lactic acid bacteria (LAB), which are commonly used in the production of fermented foods, have been gaining attention for their antifungal and antimycotoxin properties. In this work, the strain Lactobacillus plantarum UM55 was selected among other LAB for inhibiting the growth of Aspergillus flavus. Further, it is shown that cell-free supernatant (CFS) of this strain inhibits the production of aflatoxins (AFLs) by 91%. This inhibition was dependent on CFS pH, increased with increasing concentrations of CFS, and was independent of fungal growth, which was inhibited only by 32%. CFS was also effective in inhibiting the growth and AFLs production in A. parasiticus, A. arachidicola, A. nomius and A. minisclerotigenes. Further, L. plantarum UM55 CFS was analysed for the presence of organic acids and the main differences compared to controls were found in the levels of lactic acid, phenyllactic acid (PLA), hydroxyphenyllactic acid (OH-PLA), and indole lactic acid (ILA). These compounds were individually tested against A. flavus, with all of the compounds showing an inhibiting effect on fungal growth and AFLs production. PLA showed the stronger effects, and the obtained IC90 for the inhibition of growth and AFLs was of 11.9 and 0.87mg/mL, respectively. AFLs IC90 for ILA, OH-PLA and lactic acid were of 1.47, 1.80, and 3.92mg/mL, respectively. The antiaflatoxigenic properties of LAB depend on strain's capability to produce lactic acid, PLA, OH-PLA and ILA.

Exploration, antifungal and antiaflatoxigenic activity of halophilic bacteria communities from saline soils of Howze-Soltan playa in Iran.

In the present study, halophilic bacteria communities were explored in saline soils of Howze-Soltan playa in Iran with special attention to their biological activity against an aflatoxigenic Aspergillus parasiticus NRRL 2999. Halophilic bacteria were isolated from a total of 20 saline soils using specific culture media and identified by 16S rRNA sequencing in neighbor-joining tree analysis. Antifungal and antiaflatoxigenic activities of the bacteria were screened by a nor-mutant A. parasiticus NRRL 2999 using visual agar plate assay and confirmed by high-performance liquid chromatography. Among a total of 177 halophilic bacteria belonging to 11 genera, 121 isolates (68.3%) inhibited A. parasiticus growth and/or aflatoxin production. The most potent inhibitory bacteria of the genera Bacillus, Paenibacillus and Staphylococcus were distributed in three main phylogenetic clusters as evidenced by 16S rRNA sequence analysis. A. parasiticus growth was inhibited by 0.7-92.7%, while AFB1 and AFG1 productions were suppressed by 15.1-98.9 and 57.0-99.6%, respectively. Taken together, halophilic bacteria identified in this study may be considered as potential sources of novel bioactive metabolites as well as promising candidates to develop new biocontrol agents for managing toxigenic fungi growth and subsequent aflatoxin contamination of food and feed in practice.

Efficacy of feed additives to reduce the effect of naturally occurring mycotoxins fed to turkey hen poults reared to 6 weeks of age.

Corn with naturally occurring aflatoxin (AF), wheat with naturally occurring doxynivalenol (DON), and barley with naturally occurring zearalenone (ZEA) were used to make rations for feeding turkey hen poults to 6 weeks of age. Control rations with equal amounts of corn, wheat, and barley were also fed. The control rations did contain some DON while both sets of rations contained ZEA. Within each grain source, there were 4 treatments: the control ration plus 3 rations each with a different feed additive which were evaluated for the potential to lessen potential mycotoxin effects on bird performance and physiology. The additives were Biomin BioFix (2 lb/ton), Kemin Kallsil (4 lb/ton), and Nutriad UNIKE (3 lb/ton). The mycotoxin rations reduced poult body weight (2.31 vs. 2.08 ± 0.02 kg) and increased (worsened) poult feed conversion (1.47 vs. 1.51 ± 0.01) at 6 wk. Feeding the poults the mycotoxin feed also resulted in organ and physiological changes typical of feeding dietary aflatoxin although a combined effect of AF, DON, and ZEA which cannot be dismissed. The feed additives resulted in improved feed conversion to 6 wk in both grain treatment groups. The observed physiological effect of feeding the additives was to reduce relative gizzard weight for both groups and to lessen the increase in relative kidney weight for the birds fed the mycotoxin feed. In conclusion, the feed additives used in this study did alleviate the effect of dietary mycotoxins to some degree, especially with respect to feed conversion. Further studies of longer duration are warranted.

Thiosemicarbazone scaffold for the design of antifungal and antiaflatoxigenic agents: evaluation of ligands and related copper complexes.

The issue of food contamination by aflatoxins presently constitutes a social emergency, since they represent a severe risk for human and animal health. On the other hand, the use of pesticides has to be contained, since this generates long term residues in food and in the environment. Here we present the synthesis of a series of chelating ligands based on the thiosemicarbazone scaffold, to be evaluated for their antifungal and antiaflatoxigenic effects. Starting from molecules of natural origin of known antifungal properties, we introduced the thio- group and then the corresponding copper complexes were synthesised. Some molecules highlighted aflatoxin inhibition in the range 67-92% at 100 µM. The most active compounds were evaluated for their cytotoxic effects on human cells. While all the copper complexes showed high cytotoxicity in the micromolar range, one of the ligand has no effect on cell proliferation. This hit was chosen for further analysis of mutagenicity and genotoxicity on bacteria, plants and human cells. Analysis of the data underlined the importance of the safety profile evaluation for hit compounds to be developed as crop-protective agents and at the same time that the thiosemicarbazone scaffold represents a good starting point for the development of aflatoxigenic inhibitors.