Inhibition of aflatoxin B production of Aspergillus flavus, isolated from soybean seeds by certain natural plant products

Formation of filamentous fungal biofilms in water and the transformation of resistance to chlor(am)ine disinfection

Biofilms are composed of complex multi-species in nature, potentially threatening drinking water safety. In this work, the formation of single- and multi-species fungal biofilms formed by Aspergillus niger (A. niger) and Aspergillus flavus (A. flavus), and the inactivation of mature biofilms using chlor(am)ine were firstly investigated. Results revealed that the antagonistic interaction occurred between A. niger and A. flavus. Chloramination at 20 mg/L for 30 min achieved 74.74 % and 76.04 % inactivation of A. flavus and multi-species biofilm, which were 1.69- and 1.84-fold higher than that of chlorine at the same condition. However, no significant difference was observed in the inactivation of A. niger biofilm between chlorine and monochloramine disinfection due to the lower amount of extracellular polymeric substance produced by it (p > 0.05). The inactivation of biofilm by monochloramine fitted the Weibull model well. According to the Weibull model, the monochloramine resistance of biofilm were as follows: A. flavus > multi-species > A. niger biofilm. Besides, an increase in reactive oxygen levels, damage of cell membrane, and leakage of intracellular substances in biofilms were observed after chlor(am)ination. More intracellular polysaccharides and proteins were leaked in chloramination inactivation (p < 0.05). This study provides important implications for controlling fungal biofilm.

Phytochemicals analysis and aflatoxin B1 detoxification potential of leaves extract of Moringa oleifera and Calotropis procera

The present study aimed to identify the presence of certain classes of phytochemicals in the leaf extract of medicinal herbs viz. Moringa oleifera and Calotropis procera, using qualitative detection tests and explored the potential of aqueous and ethanolic extract to inhibit aflatoxin production by thin layer chromatography at 25 °C and pH (7) of different incubation times i.e. 0-, 1-, 3-, 6- and 24-h. Qualitative phytochemical analysis reported that the aqueous leave extracts of M. oleifera and C. procera contained tannins, phlobatannins, quinones, steroids, sugar, betacyanins, fatty acids, phenols, and volatile oils. Aflatoxin analysis reported that the ethanolic extract of M. oleifera was found more effective than detoxifying 100% of AFB1 after 24 h of incubation. In the case of C. procera, the aqueous extract reduced 96.5% of AFB1 and ethanolic extract reduced 96% of AFB1 after 24-h of incubation. The results revealed that natural plant products have a high potential to reduce AFB1 and could contribute to mitigation plans for AFB1. There is a need for further characterisation using techniques such as GC-MS, LC-MS, or NMR which would provide valuable information on the chemical composition of the extracts.

Ochratoxin A detoxification potentials of basil, chan, and chia seeds

The most toxic of the ochratoxins is ochratoxin A (OTA), which is primarily produced by species of Aspergillus and Penicillium that can be found in maize, wheat, coffee, red wine, and various grains. OTA induces immunotoxicity, nephrotoxicity, hepatotoxicity, teratogenicity, and carcinogenicity in both animals and humans. Thus, there is a need to identify mycotoxin detoxification agents that can effectively decontaminate OTA. Seeds of basil (Ocimum basilicum L.), chan (Hyptis suaveolens L.), and chia (Salvia hispanica L.) are functional foods capable of eliminating harmful substances. Despite this potential, the impact of these seeds on OTA detoxification remains unclear. This study reveals that milled basil, chan, and chia seeds adsorb significant levels of OTA, with chia demonstrating the highest adsorption capacity, followed by chan and basil seeds showing the least efficiency. Furthermore, milled basil, chan, and chia seeds effectively reduced OTA residues in artificial gastric and intestinal fluids, where they achieved up to 93% OTA adsorption in the former. In addition, these milled seeds were able to remove OTAs from canned, drip, and instant coffee. This study is the first to report the OTA elimination potential of basil, chan, and chia seeds.

Detection of aflatoxin producing Aspergillus flavus from animal feed in Karnataka, India

Aflatoxins are toxic carcinogenic secondary metabolite produced by Aspergillus flavus and are responsible for contamination in animal feed. The aim of the study was to determine the prevalence of aflatoxin contamination in animal feed in Karnataka state, India. The screening was performed by desiccated coconut agar and quantification of aflatoxin by liquid ammonia vapor test, TLC and ELISA. A total of 29 samples received from different places of Karnataka were analysed for aflatoxin B1. Out of 29 animal feed sample aflatoxin B1 detected in 12 samples representing 41.38% at average concentration of 288.50 μg/kg. Out of 42 isolates screened in animal feed, Aspergillus flavus was found to be in 86.2% and Aspergillus niger was 24.1%. It was observed that out of 42 isolates analyzed from animal feed, aflatoxin B1 was detected in 12 samples. Aflatoxin B1 is the most common contaminant and the method is more sensitive in screening and detection of aflatoxin B1 in the animal feed.

Efficacy of volatile compounds from Streptomyces philanthi RL-1-178 as a biofumigant for controlling growth and aflatoxin production of the two aflatoxin-producing fungi on stored soybean seeds

AIMS

This study aimed to apply the volatile organic compounds from Streptomyces philanthi RL-1-178 (VOCs RL-1-178) as a fumigant to protect soybean seeds against the two aflatoxin-producing fungi in stored soybean seeds.

METHODS AND RESULTS

The antifungal bioassay tests on potato dextrose agar (PDA) dishes showed that 30 g l-1 wheat seed inoculum of S. philanthi RL-1-178 exhibited total (100%) inhibition on Aspergillus parasiticus TISTR 3276 and Aspergillus flavus PSRDC-4. Identification of the VOCs RL-1-178 using GC-MS revealed 39 compounds with the most abundant substances being geosmin (13·75%) followed by l-linalool (13·55%), 2-mercaptoethanol (9·71%) and heneicosane (5·96%). Comparison on the efficacy of the VOCs RL-1-178 (at 30 g l-1 wheat seed culture) and their four major components (100 µl l-1 each) on the suppression of the two aflatoxin-producing fungi on PDA plates revealed that the VOCs RL-1-178 as well as geosmin, l-linalool and 2-mercaptoethanol completely inhibited (100%) mycelial growth while heneicosane showed only 70·7% inhibition. Use of the VOCs RL-1-178 (30 g l-1 ) as a biofumigant on stored soybean seeds resulted in complete protection (100%) against the infection as well as complete inhibition on production of aflatoxin (B1 , B2 and G2 ) (analysed by HPLC) by the two aflatoxin-producing fungi.

CONCLUSIONS

The VOCs RL-1-178 displayed strong inhibitory effects on A. parasiticus TISTR 3276 and A. flavus PSRDC-4 as well as inhibited aflatoxin (B1 , B2 and G2 ) production.

SIGNIFICANCE AND IMPACT OF THE STUDY

These findings suggest that the VOCs RL-1-178 can be applied as a biofumigant to control the two aflatoxin-producing fungi on stored seeds products.

Assessment of Fungal Contamination in Fish Feed from the Lake Victoria Basin, Uganda

The emergence of commercial fish farming has stimulated the establishment of fish feed factories in Uganda. However, no information is available on the safety of the feed, mainly due to lack of mycotoxin testing facilities and weak regulatory systems. A study was carried out to examine fungal colonization and mycotoxin contamination in fish feed samples (n = 147) of different types collected from nine fish farms (n = 81) and seven fish feed factories (n = 66) in the Lake Victoria Basin (LVB). Fungi were isolated in potato dextrose agar, grouped into morphotypes and representative isolates from each morphotype were identified based on the internal transcribed spacer (ITS) region of ribosomal DNA sequences. Aflatoxin B₁ (AFB₁) and total fumonisin (combinations of B₁, B₂ and B₃; hereinafter named fumonisin) levels in feed samples were determined by enzyme-linked immunosorbent assay (ELISA). A wide range of fungi, including toxigenic Aspergillus flavus and Fusarium verticillioides, were isolated from the fish feed samples. AFB₁ was detected in 48% of the factory samples and in 63% of the farm samples, with toxin levels <40 and >400 µg/kg, respectively. Similarly, 31% of the factory samples and 29% of the farm samples had fumonisin contamination ranging between 0.1 and 4.06 mg/kg. Pellets and powder had higher mycotoxin contamination compared to other commercially available fish feed types. This study shows AFB₁ as a potential fish feed safety issue in the LVB and suggests a need for more research on mycotoxin residues in fish fillets.

Molecular and structural basis of nucleoside diphosphate kinase-mediated regulation of spore and sclerotia development in the fungus Aspergillus flavus

The fundamental biological function of nucleoside diphosphate kinase (NDK) is to catalyze the reversible exchange of the γ-phosphate between nucleoside triphosphate (NTP) and nucleoside diphosphate (NDP). This kinase also has functions that extend beyond its canonically defined enzymatic role as a phosphotransferase. However, the role of NDK in filamentous fungi, especially in Aspergillus flavus (A. flavus), is not yet known. Here we report that A. flavus has two NDK-encoding gene copies as assessed by qPCR. Using gene-knockout and complementation experiments, we found that AfNDK regulates spore and sclerotia development and is involved in plant virulence as assessed in corn and peanut seed-based assays. An antifungal test with the inhibitor azidothymidine suppressed AfNDK activity in vitro and prevented spore production and sclerotia formation in A. flavus, confirming AfNDK's regulatory functions. Crystallographic analysis of AfNDK, coupled with site-directed mutagenesis experiments, revealed three residues (Arg-104, His-117, and Asp-120) as key sites that contribute to spore and sclerotia development. These results not only enrich our knowledge of the regulatory role of this important protein in A. flavus, but also provide insights into the prevention of A. flavus infection in plants and seeds, as well as into the structural features relevant for future antifungal drug development.

Evaluation of Antioxidant Activity and Growth Control Properties of Nonoscale Structure Produced from Aloe vera var. littoralis Extract on Clinical Isolates of Salmonella

The aim of the study was to examine antibacterial properties of microemulsion structure produced from Aloe vera var. littoralis extract as a new tool of nanoscale drug-like materials. Aloe vera var. littoralis (A. littoralis) extract was prepared by distillation method. A nonocarrier structure in the microemulsion system was prepared from the extract. Serial concentrations were prepared from 8 mg/mL extract and the nonocarrier containing 0.1 mg/mL pure extract and were evaluated by a disk diffusion method for 35 Salmonella clinical isolates. Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were determined by microbroth dilution assay using MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) method by an enzyme-linked immunosorbent assay(ELISA) Microplate Reader apparatus. Antioxidant activity of the extract was determined by measuring the ferric reducing ability of plasma (FRAP) assay. From 35 clinical isolates of Salmonella, 17 isolates-including resistant isolates of S.E.1103 and S.E.49-had a zone of inhibition (ZI) of 7 to 32 mm in 0.007 mg/mL of the extract. S.E.76 isolate exposed to 30 µg/mL ceftazidime disk had a ZI of 12 mm but had 10 mm in 7µg/mL of A. littoralis extract. The inhibitory effect of a nanocarrier at a concentration of 25 µg/mL by 20 mm ZI was comparable by the ceftazidime (30 µg/mL) effect. MIC50 was 0.25 mg/mL and MBC50 was 0.5 mg/mL by MTT method for the extract. It was shown that A.littoralis extract had antioxidant activity of 31.67 µM/mg that could be increased based on concentration. It was concluded that the nanocarrier had a significant effect on the studied isolates in comparison with ordinary antibiotics and had potential for use as a natural antioxidant and antimicrobial material in complementary medicine.

Prevalence of toxigenic fungi in common medicinal herbs and spices in India

Mycotoxins are unavoidable contaminants of food grains, feeds, medicinal herbs, and spices, posing as health threat to animals and humans. The objective of this study was to screen medicinal herbs and spices for fungi and mycotoxin contamination and evaluate their safety. Sixty-three samples were examined for fungal contamination and fungal load determined using standard microbiological method. Aflatoxin and citrinin were detected using thin layer chromatography and high-performance chromatography technique. Fifty-eight out of the 63 samples were contaminated, while five were free from fungal contamination. Analysis revealed that 47 % of the samples had a fungal load above 1 × 10³ cfu/g which is the permissible limit set by World Health Organization. The samples Mesua ferrea-II and Terminalia chebula-III had the highest fungal load, i.e., 5.0 × 10⁴ cfu/g. A total of 187 fungi were isolated, out of which 28 were toxigenic which included 19 aflatoxin-producing Aspergillus flavus and 9 citrinin-producing Penicillium citrinum. The natural contamination with aflatoxin B₁ was detected only in one sample, i.e., Arachis hypogaea (groundnut) which was present beyond the permissible limit. Though toxigenic fungi were isolated, mycotoxins were not detected from any of the medicinal herbs and spices. Medicinal herbs and spices are susceptible to toxigenic fungi; however, they also possess intrinsic factors that inhibit mycotoxin contamination. This study provides a basis in assessing the degree of fungal and potential mycotoxin contamination in medicinal herbs and spices.

Structural Analysis and Biological Toxicity of Aflatoxins B1 and B2 Degradation Products Following Detoxification by Ocimum basilicum and Cassia fistula Aqueous Extracts

This study showed the comparison between Ocimum basilicum and Cassia fistula (leaves and branch) aqueous extracts for their ability to detoxify of aflatoxins B1 and B2 (AFB1; 100 μg L(-1) and AFB2; 50 μg L(-1)) by In Vitro assays and decontamination studies. Results indicated that O. basilicum leaves extract was found to be highly significant (P < 0.05) in degrading AFB1 and AFB2, i.e., 90.4 and 88.6%, respectively. However, O. basilicum branch, C. fistula leaves and branch extracts proved to be less efficient in degrading these aflatoxins, under optimized conditions, i.e., pH 8, temperature 30°C and incubation period of 72 h. Moreover the antifungal activity of these plants extracts were also tested. The findings depicted that O. basilicum leaves extract showed maximum growth inhibition of aflatoxigenic isolates, i.e., 82-87% as compared to other tested plants extracts. The structural elucidation of degraded toxin products by LCMS/MS analysis showed that nine degraded products of AFB1 and AFB2 were formed. MS/MS spectra showed that most of the products were formed by the removal of double bond in the terminal furan ring and modification of lactone group indicating less toxicity as compared to parent compounds. Brine shrimps bioassay further confirmed the low toxicity of degraded products, showing that O. basilicum leaves extract can be used as an effective tool for the detoxification of aflatoxins.

Structural Elucidation and Toxicity Assessment of Degraded Products of Aflatoxin B1 and B2 by Aqueous Extracts of Trachyspermum ammi

In this study aqueous extract of seeds and leaves of Trachyspermum ammi were evaluated for their ability to detoxify aflatoxin B1 and B2 (AFB1; 100 μg L(-1) and AFB2; 50 μg L(-1)) by in vitro and in vivo assays. Results indicated that T. ammi seeds extract was found to be significant (P < 0.05) in degrading AFB1 and AFB2 i.e., 92.8 and 91.9% respectively. However, T. ammi leaves extract proved to be less efficient in degrading these aflatoxins, under optimized conditions i.e., pH 8, temperature 30°C and incubation period of 72 h. The structural elucidation of degraded toxin products by LCMS/MS analysis showed that eight degraded products of AFB1 and AFB2 were formed. MS/MS spectra showed that most of the products were formed by the removal of double bond in the terminal furan ring and modification of lactone group indicating less toxicity as compared to parent compounds. Brine shrimps bioassay further confirmed the low toxicity of degraded products, showing that T. ammi seeds extract can be used as an effective tool for the detoxification of aflatoxins.

Variation in fungal microbiome (mycobiome) and aflatoxin in stored in-shell peanuts at four different areas of China

The contamination of peanuts with Aspergillus sp. and subsequently aflatoxins is considered to be one of the most serious safety problems in the world. Mycobiome in peanuts is critical for aflatoxin production and food safety. To evaluate the biodiversity and ecological characteristics of whole communities in stored peanuts, the barcoded Illumina paired-end sequencing of the internal transcribed spacer 2 (ITS2) region of rDNA was used to characterize the peanut mycobiome monthly over a period of 1 year at four main peanut grown areas, i.e., Liaoning (LN, North East), Shandong (SD, East), Hubei (HB, Central), and Guangdong (GD, South) provinces. The fungal diversity of peanuts stored in SD was the highest with 98 OTUs and 43 genera, followed by LN, HB and GD. In peanuts stored in SD, Rhizopus, Emericella, and Clonostachys were predominant. In peanuts from LN, Penicillium, Eurotium, and Clonostachys were abundant. In peanuts from HB, Penicillium, Eurotium, and Aspergillus were higher. In GD peanuts, Eurotium, Aspergillus, and Emericella were mainly seen. The abundances of Aspergillus in LN, SD, HB, and GD were 0.53, 6.29, 10.86, and 25.75%, respectively. From the North of China to the South, that increased over the latitude, suggesting that the higher temperature and relative humidity might increase the risk of peanuts contaminated with Aspergillus and aflatoxins. During the storage, Aspergillus levels were higher at 7–12 months than in 0–6 months, suggesting that the risk increases over storage time. At 7–10 months, AFB₁ was higher in four areas, while declined further. The reduction of AFB₁ might be attributed to the inhibition and degradation of AFB₁ by Aspergillus niger or to the combination with the compounds of peanuts. This is the first study that identified the mycobiome and its variation in stored peanuts using ITS2 sequencing technology, and provides the basis for a detailed characterization of whole mycobiome in peanuts.

Removal of aflatoxin B1 and inhibition of Aspergillus flavus growth by the use of Lactobacillus plantarum on olives

Olives can be contaminated with a wide variety of molds (Aspergillus and/or Penicillium) that can be occurring naturally on fresh and processed olives and could support mycotoxin production. The aim of this work was to investigate aflatoxin B1 (AFB1) production by fungi and its bioaccumulation in olives during storage and to study the impact of the application of Lactobacillus plantarum on the inhibition of mold development and production of AFB1. Two different treatments were applied: (i) olives with natural microflora and (ii) olives inoculated with Aspergillus flavus after elimination of natural microflora. AFB1 has been extracted from olives and quantitated by high-performance liquid chromatography using a fluorescence detector. Results showed the absence of this metabolite in the olives for the season 2008 to 2009. In 2009 to 2010, AFB1 was detected at the level of 11 μg/kg. The application of L. plantarum during the storage of olives favors the reduction of the level of AFB1 to 5.9 μg/kg correlated with a decrease in the amount of molds (86.3%). The images obtained by environmental scanning electron microscopy showed that L. plantarum was able to adhere to the olive surface and probably produce a biofilm that inhibits the multiplication of yeast and fungi by oxygen competition. Results showed an increase of antioxidant activity and amount of total phenolic compounds of olives, respectively, by 24 and 8.6%. In many olives contaminated with A. flavus, AFB1 was present at an initial level of 5.15 μg/kg and increased to 6.55 μg/kg after 8 days of storage. The biological detoxification of AFB1 in olives by L. plantarum is confirmed by the reduction of the level of AFB1 to 2.12 μg/kg on day 0 and its absence after 4 days of storage.

Evaluation of allium and its seasoning on toxigenic, nutritional, and sensorial profiles of groundnut oil

Mitigation of xerophilic storage fungi-associated aflatoxin threat in culinary oil will be a new technology advantage to food industries. Groundnut oil isolate Aspergillus flavus MTCC 10680 susceptibility to Allium species (A. sativum L., A. cepa L., and A. cepa var. aggregatum) extracts, composition, and in silico confirmation of extract's phytoconstituent aflatoxin synthesis inhibition were determined. The behavior of seasoning carrier medium groundnut oil in the presence of Allium was also determined. All the Allium species extracts exhibited concentration dependent in vitro inhibition on mycelial biomass, radial growth, and toxin elaboration. The gas chromatography-mass spectrometry revealed the presence of 28, 16, and 9 compounds in the extracts of A. sativum, A. cepa, A. cepa var. aggregatum, respectively. The Allium phytocostituents-like hexadecanoic acid, 5-Octanoyl-2,4,6(1H,3H,5H)-pyrimidinetrione, Guanosine, and so on, showed higher binding energy with aflatoxin synthesis key enzyme ver1. Allium seasoning increased the typical nutty odor of the groundnut oil with sweet aroma note as well as intensification of pale yellow color. Allium seasoning exhibited the highest aflatoxin detoxification and aroma development without any nutritional loss. Culinary oil Allium seasoning has anti-aflatoxin and food additive potential for use in food industries.

Purification of an antifungal compound, cyclo(l-Pro-d-Leu) for cereals produced by Bacillus cereus subsp. thuringiensis associated with entomopathogenic nematode

Mold spoilage is the main cause of substantial economic loss in cereals and might also cause public health problems due to the production of mycotoxins. The aim of this study was to separate and purify and to identify antifungal compounds of bacterium associated with novel entomopathogenic nematode and check the antifungal property of identified compound in particular food model systems. The antifungal compound was purified using silica gel column chromatography, TLC and HPLC and its structure was elucidated using NMR (¹H NMR, ¹³C NMR, ¹H-¹H COSY, ¹H-¹³C HMBC), HRMS and Marfey's method. Based on the spectral data, the active compounds were identified as diketopiperazine [cyclo(l-Pro-d-Leu)]. The antifungal activity of cyclo(l-Pro-d-Leu) was studied by MIC and paper disk assay against Aspergillus flavus MTCC 277 and Aspergillus niger MTCC 282 and best MIC value of 8μg/ml was recorded against A. flavus. Cyclo(l-Pro-d-Leu) strongly inhibit mycelia growth of fungus and thereby affecting aflatoxin production. To investigate the potential application of the cyclo(l-Pro-d-Leu) and to eliminate fungal spoilage in food and feed, soybean and peanut were used as models. White mycelia and dark/pale green spores of A. flavus were observed in the control soybeans after 2-day incubation. However the fungal growth was not observed in soybeans treated with cyclo(l-Pro-d-Leu). Almost the same result was observed for peanuts treated with cyclo(l-Pro-d-Leu) for A. niger. The cyclo(l-Pro-d-Leu) was nontoxic to two normal human cell lines (FS normal fibroblast and L231 lung epithelial) up to 200μg/ml. Thus the diketopiperazine derivative identified in the study may be a promising alternative to chemical preservatives as a potential biopreservative which prevent fungal growth and mycotoxin formation in food and feed.

Extracts of Agave americana inhibit aflatoxin production in Aspergillus parasiticus

Toxigenic fungi invade crops prior to harvest as well as during storage and produce harmful, even carcinogenic toxins such as aflatoxins. Since consumers demand safe commodities, and due to enhanced public awareness of the dangers of many synthetic fungicides, the importance of investigating alternative, natural products to control these toxigenic fungi is clear. This study investigated the effect of aqueous extracts of Agave americana on growth, conidia and aflatoxin production. Aspergillus parasiticus strains SRRC 148, SRRC 143 (Su-1), and A. parasiticus SRRC 162, a mutant (nor-) that accumulates norsolorinic acid (NOR, an orange-coloured intermediate of the aflatoxin pathway), were first inoculated into Adye and Mateles liquid medium, then plant extracts were added, and incubated at 28 °C for 7 days. Aflatoxin and norsolorinic acid were assayed by HPLC and spectrophotometry, respectively. While the extract of A. americana stimulated growth of the studied fungi, conidiogenesis, norsolorinic acid accumulation (in the nor- mutant), and aflatoxin production were significantly affected. The reduction was produced by the extracts at concentrations higher than 5-10 mg/ml, where all types of total aflatoxin analysed (aflatoxins B1, B2, G1 and G2) were reduced from 64% to >99% in the whole culture, and a reduction of 75% of norsolorinic acid. The results of the present work indicate that extracts of A. americana may be promising safe alternatives to harmful fungicides for controlling aflatoxin contamination.

Interaction between certain moulds and aflatoxin B1 producer Aspergillus flavus NRRL 3251

The objective of this study was to evaluate biotic interaction between some mould species and active producer of aflatoxin B1 Aspergillus flavus NRRL 3251, co-cultured in yeast-extract sucrose (YES) broth. Twenty-five mould strains of Alternaria spp., Cladosporium spp., Mucor spp., A. flavus and A. niger, used as biocompetitive agents, were isolated from outdoor and indoor airborne fungi, scrapings of mouldy household walls, and from stored and post-harvest maize. Aflatoxin B1 was extracted from mould biomasses with chloroform and detected using the multitoxin TLC method. The results confirm antagonistic interaction between all strains tested. With Alternaria spp. and Cladosporium spp., aflatoxin B1 production decreased 100%, compared to detection in a single culture of A. flavus NRRL 3251 (Cmean=18.7 microg mL-1). In mixed cultures with Mucor spp., aflatoxin B1 levels dropped to (5.6-9.3) microg mL-1, and the inhibition was from 50% to 70%. Four of five aflatoxin non-producing strains of A. flavus interfered with aflatoxin production in mixed culture, and reduced AFB1 productivity by 100%. One strain showed a lower efficacy in inhibiting AFB1 production (80%) with a detectable amount of AFB1 3.7 microg mL-1 when compared to control. A decrease in toxin production was also observed in dual cultivation with A. niger strains. It resulted in 100% reduction in three strains), 90% reduction in one strain (Cmean=1.9 microg mL-1) and 80% reduction in one strain (Cmean=3.7 microg mL-1) inhibition.

Spices mycobiota and mycotoxins available in saudi arabia and their abilities to inhibit growth of some toxigenic fungi

The prevalence and population density of the mycobiota of 50 samples belonging to 10 kinds of spices (anise, black pepper, red pepper, black cumin, peppermint, cardamom, clove, cumin, ginger and marjoram) which collected from different places in Jeddah Governorate were studied. The natural occurrence of mycotoxins in those samples was also investigated. Fifteen genera and thirty - one species of fungi in addition to one species variety were isolated and identified during this study. The most common genera were Aspergillus, Penicillium and Fusarium. Aflatoxins (12~40 µg/kg) were detected in the extract of 5 samples of each of anise seeds and black pepper fruits; three samples of black cumin seeds and on sample only of each of peppermint and marjoram leaves out of 5 samples tested of each. Sterigmatocystin (15~20 µg/kg) was detected in some samples of red pepper, cumin and marjoram. The inhibitory effects of 10 kinds of powdered spices were tested against 3 toxigenic isolates of fungi (Aspergillus flavus, A. versicolor and Penicillium citrinum). Clove proved to be antimycotic compounds. It inhibited the growth of the tested toxigenic fungi. Black pepper, peppermint, cardamom, cumin and marjoram completely inhibited aflatoxins production, while black pepper and cardamom also completely inhibited sterigmatocystin production.