Mycoflora isolation and molecular characterization of Aspergillus and Fusarium species in Tunisian cereals

Wheat, barley and maize are the mainly consumed cereals in Tunisia. This study aimed to determine the mycoflora of these cereals with special focus on the mycotoxigenic Aspergillus and Fusarium species. Freshly harvested samples and other stored samples of each type of cereal (31 and 34 samples, respectively) were collected in Tunisia and cultured for fungal isolation and identification. Identification of fungal genera was based on morphological features. Aspergillus and Fusarium species were identified by species specific PCR assays complemented with DNA sequencing. Alternaria (70.83%), Eurotium (62.50%), Aspergillus (54.17%) and Penicillium (41.67%) were the most frequent fungi isolated from wheat. Penicillium (75%), Aspergillus (70%), Eurotium (65%) and Alternaria (65%) were the most frequently recovered genera from barley. The predominant genera in maize were Aspergillus(76.19%), Eurotium (42.86%), and Penicillium (38.09%). Aspergilllus, Penicillium, Fusarium and Alternaria were detected in both stored and freshly harvested grain samples. The frequencies of contamination with Aspergillus, Fusarium and Alternaria were higher in freshly harvested samples, whereas Penicillium species were more frequent in stored samples. The predominant Aspergillus species detected were A. flavus and A. niger. The Fusarium species detected were F. equiseti, F. verticillioides, F. nygamai, and F. oxysporum. This study suggested the potential risk for Aflatoxins and, to a lesser extent, for Ochratoxin A in Tunisian cereals. This is the first survey about mycoflora associated with wheat, barley and maize in Tunisia

Incidence, legislations and strategies of control of mycotoxins in North African countries

Mycotoxins are natural food and feed contaminants mainly produced by filamentous and ubiquitous fungi of genera Aspergillus, Penicillium and Fusarium. Due to the high stability of mycotoxins, contamination can occurs in the field, during storage, processing and post-processing steps, under favorable conditions of temperature and water activity. These compounds pose serious economic and health problems worldwide and show different toxicological effects in humans and animals. North African populations are exposed to the risk of mycotoxins due to consumption of contaminated food. These countries are surrounded by Mediterranean Sea and have a climate characterized by high humidity and temperature, which probably favors the growth of molds. During the last decades, many studies have reported the occurrence of different mycotoxins in food commodities in North African countries. Tolerable limits for mycotoxins have been established in these countries but legislations do not include all mycotoxins. In addition, researchers try to establish strategies to prevent and reduce mycotoxin contamination, but studies still rare and not include all mycotoxins and toxigenic fungi. This review presents an overview of the main investigations about the occurrence of mycotoxins and toxigenic mycobiota in food commodities commercialized in North African countries and the regulation limits which are in force in these countries

Aflatoxins and ochratoxin A and their Aspergillus causal species in Tunisian cereals

Occurrence of aflatoxins (AFs) AFB1, AFB2, AFG1, AFG2 and ochra toxin A (OTA) was studied in 65 samples of stored and freshly harvested wheat, barley and maize collected in Tunisia. The mycotoxins were simultaneously extracted and quantified by high performance liquid chromatography. Determination of AF-producing (section Flavi) and OTA-producing Aspergillus species (sections Nigri and Circumdati) was conducted in these samples by species-specific polymerase chain reaction (PCR). Results showed that most of maize samples were contaminated with AFs, data after storage showing lower values than those collected at harvest. All contaminated maize samples contained AFG1 and AFG2, among which 27.78% also had AFB1 and AFB2. This AFs pattern was consistent with the A. parasiticus toxin profile. A. flavus however showed the highest frequency in maize but was also found in barley and wheat where no AFs were detected. In contrast, OTA was neither found in maize nor in barley and only one wheat sample contained OTA. A. niger was the only OTA-producing species detected

Phylogenetic analysis and growth profiles of Fusarium incarnatum-equiseti species complex strains isolated from Tunisian cereals

The Fusarium incarnatum-equiseti species complex (FIESC) is a phylogenetically rich complex. It includes more than 30 cryptic phylogenetic species, making morphological identification problematic. FIESC has previously been detected in Tunisian cereals, but knowledge on the phylogeny and the ecophysiology of their species is lacking. In this work a phylogenetic analysis was performed using partial sequences of the translation elongation factor 1a gene (EF1a) of three FIESC strains isolated from barley and wheat from Tunisia, situated south in the Mediterranean basin, and additional strains from other countries. The results indicated that all Tunisian strains clustered with FIESC 5 group (F. clavum) together with other Spanish FIESC 5 strains also isolated from cereals. Growth rate profiles of the Tunisian strains were also determined on wheat and sorghum based media at a range of temperatures (15, 20, 25, 30, 35 and 40 ◦C) and water potential values (− 0.7, − 2.8, − 7.0, and − 9.8 MPa, corresponding to 0.995, 0.98, 0.95 and 0.93 aw values). Optimal growth was observed at 20–30 ◦C and between − 0.7 and − 7.0 MPa on both substrates (wheat and sorghum). The highest growth rate for the three strains was seen at 25 ◦C combined with − 2.8 MPa. The comparison between the growth profiles of Tunisian and Spanish FIESC 5 strains showed similar trends with some interesting differences regarding temperature and water potential factors. Tunisian strains seem to perform better between 15 and 30 ◦C and, notably, at even lower water potentials included − 9.8 Mpa. This might suggest that tolerance to low water potentials might be for Tunisian strains a more important selective clue than to higher temperatures. These results appeared to be consistent with a population well adapted to the present climatic conditions and predicted scenarios for North Africa

Adult gaucher disease in southern Tunisia: report of three cases

Abstract Background Gaucher disease (GD) is the most frequent lysosomal storage disorder; type 1 is by far the most common form. It is characterized by variability in age of onset, clinical signs and progression. It is usually diagnosed in the first or second decade of life with the appearance of bone pains, splenomegaly and thrombocytopenia, but the disease may be diagnosed at any age between 1 and 73 years. In the present study, we report 3 cases with late onset of GD in whom the disease was a surprise finding including one patient with Parkinson disease. This late onset is described as an adult form of Gaucher disease. Findings Molecular investigation showed mutational homogeneity in Tunisian adult patients suffering from GD. Indeed, all patients carry the p.N370S mutation: two patients at a homozygous state and one patient at compound heterozygous state. Conclusion The p.N370S mutation presents a large variability in the onset of the disease and its clinical manifestation supporting the view that GD should be considered as a continuum phenotype rather than a predefined classification.</p

Prevalence of piroplasms in small ruminants in North-West Tunisia and the first genetic characterisation of

In this study, the prevalence of piroplasms in sheep and goats was assessed with Giemsa-stained blood smear examination, PCR and nested PCR-restriction fragment length polymorphism (RFLP) to identify Babesia and Theileria species, respectively, in 338 small ruminants (172 sheep and 166 goats) from three sites in North-West Tunisia during the 2011 summer season. The overall infection prevalence of piroplasms in Giemsa-stained blood smears was 3.2% (11/338), with a parasitaemia ranging from 0.01 to 0.05%. PCR detected two species, namely Babesia ovis (in sheep and goats) and Theileria ovis (in sheep), with an overall prevalence of 16.3%. The molecular prevalence of B. ovis was significantly higher in sheep than in goats (17.4% and 9%, respectively, p = 0.034). The same trend was observed for T. ovis in sheep and goats (5.8% and 0%, respectively, p = 0.004). Comparison of the partial sequences of the 18S ssu rRNA gene revealed 100% similarity amongst Babesia from sheep and goats. The single Theileria sequence in this study showed 100% similarity to T. ovis. A high similarity with all the blasted genotypes was reported for Theileria and Babesia sequences. This is the first molecular detection of B. ovis and genetic characterisation of small ruminants’ piroplasms in Africa