Diversity in secondary metabolites including mycotoxins from strains of aspergillus section nigri isolated from raw cashew nuts from Benin, West Africa

Open access JournalIn a previous study, raw cashew kernels were assayed for the fungal contamination focusing on strains belonging to the genus Aspergillus and on aflatoxins producers. These samples showed high contamination with Aspergillus section Nigri species and absence of aflatoxins. To investigate the diversity of secondary metabolites, including mycotoxins, the species of A. section Nigri may produce and thus threaten to contaminate the raw cashew kernels, 150 strains were isolated from cashew samples and assayed for their production of secondary metabolites using liquid chromatography high resolution mass spectrometry (LC-HRMS). Seven species of black Aspergilli were isolated based on morphological and chemical identification: A. tubingensis (44%), A. niger (32%), A. brasiliensis (10%), A. carbonarius (8.7%), A. luchuensis (2.7%), A. aculeatus (2%) and A. aculeatinus (0.7%). From these, 45 metabolites and their isomers were identified. Aurasperone and pyranonigrin A, produced by all species excluding A. aculeatus and A. aculeatinus, were most prevalent and were encountered in 146 (97.3%) and 145 (95.7%) isolates, respectively. Three mycotoxins groups were detected: fumonisins (B2 and B4) (2.7%) ochratoxin A (13.3%), and secalonic acids (2%), indicating that these mycotoxins could occur in raw cashew nuts. Thirty strains of black Aspergilli were randomly sampled for verification of species identity based on sequences of β-tubulin and calmodulin genes. Among them, 27 isolates were positive to the primers used and 11 were identified as A. niger, 7 as A. tubingensis, 6 as A. carbonarius, 2 as A. luchuensis and 1 as A. welwitschiae confirming the species names as based on morphology and chemical features. These strains clustered in 5 clades in A. section Nigri. Chemical profile clustering also showed also 5 groups confirming the species specific metabolites production

The evolving SARS-CoV-2 epidemic in Africa: Insights from rapidly expanding genomic surveillance

INTRODUCTION Investment in Africa over the past year with regard to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) sequencing has led to a massive increase in the number of sequences, which, to date, exceeds 100,000 sequences generated to track the pandemic on the continent. These sequences have profoundly affected how public health officials in Africa have navigated the COVID-19 pandemic. RATIONALE We demonstrate how the first 100,000 SARS-CoV-2 sequences from Africa have helped monitor the epidemic on the continent, how genomic surveillance expanded over the course of the pandemic, and how we adapted our sequencing methods to deal with an evolving virus. Finally, we also examine how viral lineages have spread across the continent in a phylogeographic framework to gain insights into the underlying temporal and spatial transmission dynamics for several variants of concern (VOCs). RESULTS Our results indicate that the number of countries in Africa that can sequence the virus within their own borders is growing and that this is coupled with a shorter turnaround time from the time of sampling to sequence submission. Ongoing evolution necessitated the continual updating of primer sets, and, as a result, eight primer sets were designed in tandem with viral evolution and used to ensure effective sequencing of the virus. The pandemic unfolded through multiple waves of infection that were each driven by distinct genetic lineages, with B.1-like ancestral strains associated with the first pandemic wave of infections in 2020. Successive waves on the continent were fueled by different VOCs, with Alpha and Beta cocirculating in distinct spatial patterns during the second wave and Delta and Omicron affecting the whole continent during the third and fourth waves, respectively. Phylogeographic reconstruction points toward distinct differences in viral importation and exportation patterns associated with the Alpha, Beta, Delta, and Omicron variants and subvariants, when considering both Africa versus the rest of the world and viral dissemination within the continent. Our epidemiological and phylogenetic inferences therefore underscore the heterogeneous nature of the pandemic on the continent and highlight key insights and challenges, for instance, recognizing the limitations of low testing proportions. We also highlight the early warning capacity that genomic surveillance in Africa has had for the rest of the world with the detection of new lineages and variants, the most recent being the characterization of various Omicron subvariants. CONCLUSION Sustained investment for diagnostics and genomic surveillance in Africa is needed as the virus continues to evolve. This is important not only to help combat SARS-CoV-2 on the continent but also because it can be used as a platform to help address the many emerging and reemerging infectious disease threats in Africa. In particular, capacity building for local sequencing within countries or within the continent should be prioritized because this is generally associated with shorter turnaround times, providing the most benefit to local public health authorities tasked with pandemic response and mitigation and allowing for the fastest reaction to localized outbreaks. These investments are crucial for pandemic preparedness and response and will serve the health of the continent well into the 21st century

Propagation of mycotoxigenic fungi in maize stores by postharvest insects

Published online: 01 March 2009Maize pests feeding on grains can transmit with their movement fungi harmful to human and animal health. The aim of the present work was to study the immigration and the dynamics of storage pests in traditional African maize granaries and the fungal spectrum associated with these insects. Treatments were (i) maize cobs protected just after pollination with gauze and stored thereafter, and (ii) unprotected maize cobs as controls. Eight different species of insects were identified in stores. No Prostephanus truncatus (Horn) was found in ‘protected’ maize during the 6 months of storage, but their mean number reached 239 individuals per kilogram after just 3 months of storage in the ‘unprotected’ stores. Similarly, significantly more Sitophiluszeamais (Motschulsky) were recovered from the unprotected than the protected maize treatment. Nine fungal species were found to be associated with the storage insects. On ‘non-protected’ cobs the genus Fusarium (36.05%) was the most frequently identified, followed by Penicillium (23.50%), Rhizoctonia (5.65%) and Aspergillus (3.95%). On protected cobs, Rhizoctonia sp. was most frequent (16.76%), followed by Fusarium spp. (16.62%), Penicillium spp. (8.24%) and Aspergillus spp. (2.33%). The toxigenic species encountered were Aspergillus flavus Link, Aspergillus parasiticus Speare and Fusarium verticillioïdes (Sacc.). Cathartus quadricollis (Guérin) appeared to carry more fungi towards the store, mainly Penicillium spp. (51.47%), Aspergillus spp. (46.56%) and Fusarium spp. (32.01%). Storage pests, in particular C. quadricollis and S. zeamais, play an important role in the contamination of maize with fungi, especially those that produce toxins

PICS hermetic storage bags ineffective in controlling infestations of Prostephanus truncatus and Dinoderus spp. in traditional cassava chips

Early viewCassava chips were stored for 8 months in PICS bags, with half of the bags having a natural initial insectinfestation, and the other half having this initial natural infestation augmented with 50 Prostephanustruncatus adults. Chips stored in traditional woven polypropylene bags served as controls. Oxygen levelsvaried during storage from 19.98 to 17.56%, 20.4 to 18.40%, and 20.24 to 19.92%, respectively, in PICS bagswith augmented infestation (PICS-A), PICS bags under natural infestation levels (PICS-N) and polypropylenebags (WPP). Carbon dioxide levels varied from 0.73 to 3.90%, 0.65e3.56%, and 0.20e0.61%,respectively, in the three types of bags. P. truncatus populations were significantly higher in PICS-Areaching 98.66 7.21 individuals/kg at the end of storage, compared to 92.66 4.71 in PICS-N and100.55 3.56 in WPP. Dinoderus spp. density was significantly higher in WPP with 270.55 20.59 individuals/kg after 8 months. The number of holes on chips and weight losses also increased with storageduration in all three treatments, but were significantly higher in WPP. Holes created by insects werenoticed in PICS bags and were more important in the inner HDPE (high-density polyethylene) layer thanin the outer HDPE layer. Up to 1913.00 114.13 holes were observed on the inner HDPE layer of PICS bagsand 1039.00 29.40 in the outer HDPE layer. Hermetic storage bags prolong the storability of chips byapproximately 1 month. PICS efficacy was probably affected by the large size of traditional cassava chipswith large airspaces between individual chips, leading to a large oxygen store for insects which could notbe used up through biotic activity, so that bags were not hermetic. In conclusion, PICS bags cannot berecommended for the storage of large sized traditional cassava chips

Postharvest insect infestation in maize grain stored in woven polypropylene and in hermetic bags

Maize was artificially infested with either 10 or 25 individual Prostephanus truncatus (Horn) and Sitophilus zeamais (Motschulsky) or a mixture of both, and stored in a hermetic grain bag (HGB) or a woven polypropylene bag (WPB) for 150 days. Population growth of P. truncatus and S. zeamais during storage was low in HGB, while in WPB, the insect population increased significantly with storage duration. Mortality rate during storage was significantly higher in HGB than in WPB. After 60 days of storage, the average mortality rate of 99.50% was observed in HGB infested with 25 P. truncatus, and 100% for S. zeamais at the same infestation density after 90 days of storage. Grain losses were significantly lower in HGB compared with WPB. Less than 0.5 and 6.0% losses were obtained, respectively, for S. zeamais and P. truncatus in HGB infested with 25 individual insects after 150 days of storage, whereas losses of 19.2% (infestation with S. zeamais) and 27.1% (infestation with P. truncatus) were observed in WPB. HGB seems to be resistant to the perforation of S. zeamais, but not to P. truncatus. The moisture content of maize grains stored in HGB remained practically the same during storage, compared with the levels in WPB, which reduced with storage time. WPB could be used for maize storage, protecting it against insect infestation without the need for insecticide use

Augmented release of Teretrius nigrescens Lewis (Coleoptera: Histeridae) for the control of Prostephanus truncatus (Horn) (Coleoptera: Bostrichidae) in stored cassava chips

A trial was set up in northern Benin to evaluate the potential of Teretrius nigrescens to reduce the infestation and damage to cassava chips caused by storage insects. Cassava chips were stored for 5 months in mud silos and 50 adults of T. nigrescens were added when the stores were first filled. Stores where no predator was released were monitored as controls. The main storage insects observed were Prostephanus truncatus and Dinoderus spp. Initial chip weight varied between 102 and 246 g with no difference between treatments. Chip weight and number of holes on chips initially differed between treatments after 2 months of storage. After 3 months of storage, losses reached 40–50% without T. nigrescens and 30–40% when cassava chips were stored with T. nigrescens. A farmer can increase his profit by 1437 Fcfa/100 kg (1$=560 Fcfa, 1£=968 Fcfa; 1€=656 Fcfa, as on 2 December 2005) through the use of T. nigrescens because losses are reduced by 11%. Data analysis showed that there were significant differences ([Math Processing Error]) between the two treatments for the number of holes, number of insects, weight of each chip as well as damage. There were twice as many P. truncatus and holes on chips in stores where T. nigrescens was not released. The addition of the predator to farmers’ stores is an economic option for controlling losses due to insects in cassava chips

Infarctus du myocarde chez le Togolais : Facteurs de risque eyt interet du bilan biochimique dans la prise en charge Des malades. Etude preliminaire a propos de 35 cas colliges dans trois unites de soins cardiologiques de Lome

Le diagnostic de l’infarctus du myocarde (IDM) chez les noirs n’est pas aisé. Effet l’électrocardiographie (ECG) présente souvent chez ces derniers, des atypies de repolarisation. Le dosage des enzymes cardiaques devient donc incontournable. Notre objectif est d'évaluer les facteurs de risque chez les malades Togolais atteints d’IDM et de mesurer les activités biochimiques du myocarde chez ces patients, de préciser l’intérêt de ce bilan dans diagnostic et le suivi de ces derniers. Il s’agit d’une étude rétrospective analytique, couvrant une période de 12 ans. Chez nos patients les concentrations de CK et CK-MB sont respectivement : 1056±551U/L, 555±741U/L versus 202±59U/L, 4±6U/L chez les témoins. Le bilan biochimique a permis le diagnostic de 17,85% d’IDM au moment où les modifications de l’ECG n’étaient pas patentes. Ce bilan a été réalisé dans les 24 heures qui suivent la précordialgie, seulement dans 40% des cas. Le bilan chimique du myocarde permet un diagnostic précoce et efficace de l’IDM, lorsque l’ECG est encore non concluant. The diagnosis of the myocardial infraction in the blacks is not easy. Because the electrocardiogram in this case presents atypies of repolarisation. The dosage of cardiac enzymes is necessary. Our aim is to evaluate the risk factors upon the Togolese, to measure the biochemical activities of the myocardium and finally, to lay emphasis on the interest of these exams in the diagnosis and check-ups. It is about retrospective analyses covering a period of 12 years. In our patients the concentration of Ck and CK-MB are respectively 1056 ± 551 UL, 555 ± 741 U/L versus 202 ± 59 U/L, 4 ± 6 U/L in the witnesses. The biochemical exams have permitted to make diagnosis of 17.85% of the Myocardial Infaction during the moment when modification of the ECG is not visible. These exams are realised within 24h after the precordial pains only in 40% of the cases. The biochemical exams permit early and efficient diagnosis of the myocardial infarction whenever the ECG is still doubtful

Mycoflora and occurrence of aflatoxin in dried vegetables in Benin, Mali and Togo, West Africa

Fungal infection and aflatoxin contamination was evaluated on 180 samples of dried vegetables such as okra, hot chilli, tomato, melon seeds, onion and baobab leaves from Benin, Togo and Mali collected in September to October 2006. These products are dried to preserve them for lean periods and decrease their perishability. Fungal contamination was evaluated after plating on selective media with a total of 561 fungal isolates identified, ranging from 18 in tomato and 218 in baobab leaves. Baobab leaves, followed by hot chilli and okra showed high incidence of fungal contamination compared to the other dried vegetables, while shelled melon seeds, onion leaves and dried tomato had lower levels of fungal contamination. Species of Aspergillus were dominant on all marketed dried vegetables irrespective of country. Mycotoxin assessment by Reversed-Phase High Performance Liquid Chromatography showed that only okra and hot chilli were naturally contaminated with aflatoxin B(1) and aflatoxin B(2), at concentrations of 6.0 microg/kg on okra and 3.2 microg/kg on hot pepper. This is the first time that mycotoxigenic fungi and resultant toxins were found on dried vegetable products sampled from African markets. Previous reports have mostly highlighted the risk of mycotoxin exposure from staple crops in Africa, but such risks now need to be evaluated for other products such as dried vegetables