Comportement de quelques lignées de riz NERICA en culture de bas–fond dans la région de Kinshasa, République Démocratique du Congo (RDC)

Une étude visant l’accroissement de la production locale de variétés améliorées du riz de bas-fond a été menée à Kinshasa entre les mois d’Octobre 2009 et Mars 2010. Cette étude avait pour but d’évaluer la performance de quatre lignées de riz de variété améliorée NERICA de  bas-fond en vue d’identifier la meilleure lignée à vulgariser en République Démocratique du Congo (RDC). Les résultats de l’essai conduit suivant un dispositif en blocs complets randomisés avec quatre répétitions ont montré que toutes les quatre lignées testées sont bonnes, présentant un poids de 1000 grains élevé. Cependant, du point de vue numérique, la lignée NL-16 présente le meilleur poids (30, 43±1,63 gr). A cet effet, toutes ces lignées peuvent être retenues et recommandées comme variétés de culture en mettant un accent particulier sur la lignée NL-16. © 2013 International Formulae Group. All rights reserved.Mots clés: Productivité, pyriculariose, RDC

An African Salmonella Typhimurium ST313 sublineage with extensive drug-resistance and signatures of host adaptation

Abstract: Bloodstream infections by Salmonella enterica serovar Typhimurium constitute a major health burden in sub-Saharan Africa (SSA). These invasive non-typhoidal (iNTS) infections are dominated by isolates of the antibiotic resistance-associated sequence type (ST) 313. Here, we report emergence of ST313 sublineage II.1 in the Democratic Republic of the Congo. Sublineage II.1 exhibits extensive drug resistance, involving a combination of multidrug resistance, extended spectrum β-lactamase production and azithromycin resistance. ST313 lineage II.1 isolates harbour an IncHI2 plasmid we name pSTm-ST313-II.1, with one isolate also exhibiting decreased ciprofloxacin susceptibility. Whole genome sequencing reveals that ST313 II.1 isolates have accumulated genetic signatures potentially associated with altered pathogenicity and host adaptation, related to changes observed in biofilm formation and metabolic capacity. Sublineage II.1 emerged at the beginning of the 21st century and is involved in on-going outbreaks. Our data provide evidence of further evolution within the ST313 clade associated with iNTS in SSA

A genomic appraisal of invasive Salmonella Typhimurium and associated antibiotic resistance in sub-Saharan Africa

Invasive non-typhoidal Salmonella (iNTS) disease manifesting as bloodstream infection with high mortality is responsible for a huge public health burden in sub-Saharan Africa. Salmonella enterica serovar Typhimurium (S. Typhimurium) is the main cause of iNTS disease in Africa. By analysing whole genome sequence data from 1303 S. Typhimurium isolates originating from 19 African countries and isolated between 1979 and 2017, here we show a thorough scaled appraisal of the population structure of iNTS disease caused by S. Typhimurium across many of Africa’s most impacted countries. At least six invasive S. Typhimurium clades have already emerged, with ST313 lineage 2 or ST313-L2 driving the current pandemic. ST313-L2 likely emerged in the Democratic Republic of Congo around 1980 and further spread in the mid 1990s. We observed plasmid-borne as well as chromosomally encoded fluoroquinolone resistance underlying emergences of extensive-drug and pan-drug resistance. Our work provides an overview of the evolution of invasive S. Typhimurium disease, and can be exploited to target control measures

A genomic appraisal of invasive Salmonella Typhimurium and associated antibiotic resistance in sub-Saharan Africa

Invasive non-typhoidal Salmonella (iNTS) disease manifesting as bloodstream infection with high mortality is responsible for a huge public health burden in sub-Saharan Africa. Salmonella enterica serovar Typhimurium (S. Typhimurium) is the main cause of iNTS disease in Africa. By analysing whole genome sequence data from 1303 S. Typhimurium isolates originating from 19 African countries and isolated between 1979 and 2017, here we show a thorough scaled appraisal of the population structure of iNTS disease caused by S. Typhimurium across many of Africa’s most impacted countries. At least six invasive S. Typhimurium clades have already emerged, with ST313 lineage 2 or ST313-L2 driving the current pandemic. ST313-L2 likely emerged in the Democratic Republic of Congo around 1980 and further spread in the mid 1990s. We observed plasmid-borne as well as chromosomally encoded fluoroquinolone resistance underlying emergences of extensive-drug and pan-drug resistance. Our work provides an overview of the evolution of invasive S. Typhimurium disease, and can be exploited to target control measures

Control of Aflatoxin Production in Cassava Produced by Dry Fermentation in North Kivu, Democratic Republic of Congo

Traditionally, cassava (Manihot esculenta Crantz) is transformed by fermentation in water (retting) or in the open air (dry fermentation) in the DRC. In the east of the country (North Kivu), dry fermentation is the main technique for processing cassava for its detoxification and conservation. The Congolese farmers ferment the cassava to the open air using a preselected microferment contained in the scrapings of the fermented cassava previously called "MUSIYIRO". These fermentations are spontaneously directed by the microorganisms of the uncontrolled autochthonous flora. Unfortunately, toxinogenic molds are often more active in the fermentation process during which they also produce aflatoxins. This study was undertaken to help prevent the production of aflatoxins in cassava during this process. To do this, we substituted the traditional ferment with a strain of Rhizopus oryzae used as starter (microferment). Six successive replications, in controlled fermentation and uncontrolled fermentation, in a peasant environment (Beni, North Kivu) and fermentation directed by the strain of R. oryzae were carried out. Aflatoxins were then dosed in both groups of cassava flours. The results of the assay revealed an absence of aflatoxins in cassava fermented by scrapings from fermentation led by R. oryzea, while the non-directed fermentation controls were all contaminated with aflatoxins. These results show that it is possible to prevent the production of aflatoxins in cassava during fermentation when an aflatoxin-inhibiting microbial biomass is used which can progressively invade and colonize the fermentation site and thereby control the fermentation activities of cassava

Development of Quality Protein Maize (QPM) Inbred Lines and Genetic Diversity Assessed with ISSR Markers in a Maize Breeding Program

Very few studies have been conducted to develop new quality protein maize (QPM) varieties adapted to various agro-ecological conditions in Africa. Such QPM varieties with high grain yield, genes for resistance to local disease and pests would contribute to increased grain production and to alleviate poverty and malnutrition. During the first step of the QPM breeding program in the DR-Congo, 137 inbred lines were developed and selected in the field based on various agro-morphometric characteristics. Molecular analysis revealed high level of genetic variability among inbreds. The level of polymorphic loci observed with ISSR markers varied between 74% and 80%. Nei’s gene diversity and Shannon’s information index values varied from 0.22 to 0.27 and from 0.34 to 0.41, respectively. The majority of inbred lines were distantly related. In fact, more than 87% of genetic distance values were above 0.50. The genetic distance values among the different parental maize accessions varied from 0.39 to 0.72. Inbred lines from the same parental accession were also not genetically close with genetic distance values varying from 0.28 to 0.59. More importantly, the ISSR data are useful in the selection of inbred lines to be tested for general and specific combining abilities and further development of synthetics

First report of the South American tomato pinworm Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) and its damage in the Democratic Republic of Congo

Tuta absoluta (Meyrick) (Lepidoptera, Gelechiidae), a highly devastating and invasive pest attacking tomatoes either in greenhouses or in open fields, is currently spreading throughout many countries in Africa. Six major vegetable production areas in Kinshasa, Democratic Republic of Congo (DRC), were surveyed between October and November 2016 to report any possible occurrence of the invasive Tuta absoluta. Morphological identification of the sampled adult insect individuals was based on phenotypic characters using a stereomicroscope while molecular identification was carried out using polymerization chain reaction-based approaches targeting the mitochondrial cytochrome oxidase subunit I (COI) gene. Results showed that T. absoluta was found in a commercial tomato farm in Nsele area, while it was absent in the five other sampled sites. Phylogenetic analysis revealed that T. absoluta populations found in Nsele were genetically close to those from Tunisia and Kenya. This is the first report of T. absoluta occurrence and damage in tomatoes grown in DRC where effective and sustainable pest management programs against this invasive insect should be developed and implemented to avoid major crop yield and economic losses