Combined Effects of Earthworms and Plant Growth-Promoting Rhizobacteria (PGPR) on the Phytoremediation Efficiency of <em>Acacia mangium</em> in Polluted Dumpsite Soil in Bonoua, Côte d’Ivoire

The impact of earthworms and plant growth-promoting rhizobacteria (PGPR) on the remediation in polluted dumpsite soil was performed in a greenhouse pot culture with Acacia mangium inoculated or not (control: T0) with Pontoscolex corethrurus (T1) and with Bradyrhizobium (T2); and inoculated with Pontoscolex corethrurus and Bradyrhizobium (T3). Our results showed the presence of Bradyrhizobium and/or earthworms significantly increase (P < 0.05) in the height (2-fold), total dry biomass weight (7- to 15-fold) and metal uptake of the plant (2 to 10-fold), as compared with the non-inoculated plant. The presence of both inoculants (Bradyrhizobium and earthworm) enhanced soil Pb/Ni/Cr mobility and bioavailability in metal-contaminated soil, and increased 15-fold the total plant biomass and 10-fold metal accumulation in plant biomass, as compared with plant inoculated with earthworms or Bradyrhizobium. In addition, the presence of earthworms and/or Bradyrhizobium promoted the phytoimmobilization process of Ni, Cr and Pb preferentially in Acacia mangium roots than in shoot tissue. Our experiments highlight the importance of soil organisms on the phytoremediation efficiency. It appears that earthworms and/or Bradyrhizobium have the potential to enhance the phytoextraction efficiency of plants in metal-contaminated soil

Implications des communautés bactériennes ferri-réductrices et des paramètres environnementaux dans le fonctionnement et la qualité des sols de rizières (Thaïlande et Côte d'Ivoire)

This work was performed to define the role of iron reducing bacteria (IRB) on the iron mobilization in two types of paddy fields presented different environmental problems. One is affected by salinity and received organic matter (Thailand) and the other by ferrous toxicity (Ivory Coast). Different approaches were adopted to characterize soil and water properties and determine in experiments populations and activities of IRB. Main parameters involved are salinity, rhizosphere, organic matter and iron bacterial reducing activities. Furthermore, the study of the structure of bacterial populations was done using molecular biology (PCR-TTGE). In Thai paddy soils, the results show that salinity limit bacterial communities proliferation. But the addition of organic matter improves bacterial growth and activities and remediates rice production. Bacterial populations observed in saline and non saline condition, presented halotolerant (Clostridium beijerinckii ; Bacillus sp. ; Oceanobacillus sp., Shewanella sp.), halophile (Virgibacillus, Alkaliphilus metalliredigens, Bacillus megaterium), or halosensitive characteristic, allowing the activity of bacterial communities in different medium conditions. In Ivory Coast paddy soils, the environmental conditions are more reducing with the presence of a large community of sulphate-reducing bacteria (Desulfovribrio desulfuricans). A large diversity of iron reducing communities, predominantly fermentative bacteria (Bacillus sp.), seems to contribute efficiently to iron reduction and solubilization. Iron reducing bacterial activity deleterious in Ivory Coast but beneficial in Thailand, appears as a parameter and indicator of the quality of paddy soil.Ce travail a été effectué pour définir le rôle des bactéries ferri-réductrices sur la mobilisation du fer dans deux types de situations environnementales : l'une où les rizières sont soumises à la salinité et à des apports de matières organiques (Thaïlande) et l'autre où la toxicité ferreuse se développe fortement (Côte d'Ivoire). Diverses approches ont été adoptées allant de la caractérisation des sols et des eaux in situ à des études expérimentales au laboratoire en distinguant l'impact de divers paramètres (amendement organique, salinité, rhizosphère, teneur et nature des matières organiques des sols). Pour les sols de Thaïlande, les résultats montrent que la salinité limite la prolifération des communautés bactériennes. L'apport de matières organiques, même faible, améliore la croissance et les activités des communautés bactériennes dans les zones salines. Une adaptabilité à la salinité est observée pour diverses populations de bactéries constituant des consortia ferri-réducteurs cultivables ou non, comportant au moins 4 à 5 populations identifiées. Ces consortia possèdent, pour certains des populations ferri-réductrices communes à l'ensemble des conditions (salines vs non salines), des populations soit halotolérantes (Clostridium beijerinckii ; Bacillus sp. ; Oceanobacillus sp., Shewanella sp.), soit halophiles (Virgibacillus, Alkaliphilus metalliredigens, Bacillus megaterium), soit halosensibles, favorisant le maintien des activités dans des conditions de milieux variables. En Côte d'Ivoire, les conditions de milieu semble plus réductrices avec la présence d'une forte communauté bactérienne sulfato-réductrice (Desulfovribrio desulfuricans) et d'une forte communauté bactérienne ferri-réductrice, majoritairement fermentaire (Bacillus sp.), qui contribuerait efficacement à la réduction et solubilisation du fer. L'activité bactérienne ferri réductrice délétère en Côte d'Ivoire mais bénéfique en Thaïlande, apparaît comme un paramètre et un indicateur de la qualité des sols de rizières

Involvement of iron reducing bacterial communities and of environmental parameters in the functioning and quality of paddy soils (Thailand and Ivory Coast)

Ce travail a été effectué pour définir le rôle des bactéries ferri-réductrices sur la mobilisation du fer dans deux types de situations environnementales : l’une où les rizières sont soumises à la salinité et à des apports de matières organiques (Thaïlande) et l’autre où la toxicité ferreuse se développe fortement (Côte d’Ivoire). Diverses approches ont été adoptées allant de la caractérisation des sols et des eaux in situ à des études expérimentales au laboratoire en distinguant l’impact de divers paramètres (amendement organique, salinité, rhizosphère, teneur et nature des matières organiques des sols). Pour les sols de Thaïlande, les résultats montrent que la salinité limite la prolifération des communautés bactériennes. L’apport de matières organiques, même faible, améliore la croissance et les activités des communautés bactériennes dans les zones salines. Une adaptabilité à la salinité est observée pour diverses populations de bactéries constituant des consortia ferri-réducteurs cultivables ou non, comportant au moins 4 à 5 populations identifiées. Ces consortia possèdent, pour certains des populations ferri-réductrices communes à l’ensemble des conditions (salines vs non salines), des populations soit halotolérantes (Clostridium beijerinckii ; Bacillus sp. ; Oceanobacillus sp., Shewanella sp.), soit halophiles (Virgibacillus, Alkaliphilus metalliredigens, Bacillus megaterium), soit halosensibles, favorisant le maintien des activités dans des conditions de milieux variables. En Côte d’Ivoire, les conditions de milieu semble plus réductrices avec la présence d’une forte communauté bactérienne sulfato-réductrice (Desulfovribrio desulfuricans) et d’une forte communauté bactérienne ferri-réductrice, majoritairement fermentaire (Bacillus sp.), qui contribuerait efficacement à la réduction et solubilisation du fer. L’activité bactérienne ferri réductrice délétère en Côte d’Ivoire mais bénéfique en Thaïlande, apparaît comme un paramètre et un indicateur de la qualité des sols de rizières.This work was performed to define the role of iron reducing bacteria (IRB) on the iron mobilization in two types of paddy fields presented different environmental problems. One is affected by salinity and received organic matter (Thailand) and the other by ferrous toxicity (Ivory Coast). Different approaches were adopted to characterize soil and water properties and determine in experiments populations and activities of IRB. Main parameters involved are salinity, rhizosphere, organic matter and iron bacterial reducing activities. Furthermore, the study of the structure of bacterial populations was done using molecular biology (PCR-TTGE). In Thai paddy soils, the results show that salinity limit bacterial communities proliferation. But the addition of organic matter improves bacterial growth and activities and remediates rice production. Bacterial populations observed in saline and non saline condition, presented halotolerant (Clostridium beijerinckii ; Bacillus sp. ; Oceanobacillus sp., Shewanella sp.), halophile (Virgibacillus, Alkaliphilus metalliredigens, Bacillus megaterium), or halosensitive characteristic, allowing the activity of bacterial communities in different medium conditions. In Ivory Coast paddy soils, the environmental conditions are more reducing with the presence of a large community of sulphate-reducing bacteria (Desulfovribrio desulfuricans). A large diversity of iron reducing communities, predominantly fermentative bacteria (Bacillus sp.), seems to contribute efficiently to iron reduction and solubilization. Iron reducing bacterial activity deleterious in Ivory Coast but beneficial in Thailand, appears as a parameter and indicator of the quality of paddy soil

Implications des communautés bactériennes ferri-réductrices et des paramètres environnementaux dans le fonctionnement et la qualité des sols de rizières (Thaïlande et Côte d'Ivoire)

Ce travail a été effectué pour définir le rôle des bactéries ferri-réductrices sur la mobilisation du fer dans deux types de situations environnementales : l une où les rizières sont soumises à la salinité et à des apports de matières organiques (Thaïlande) et l autre où la toxicité ferreuse se développe fortement (Côte d Ivoire). Diverses approches ont été adoptées allant de la caractérisation des sols et des eaux in situ à des études expérimentales au laboratoire en distinguant l impact de divers paramètres (amendement organique, salinité, rhizosphère, teneur et nature des matières organiques des sols). Pour les sols de Thaïlande, les résultats montrent que la salinité limite la prolifération des communautés bactériennes. L apport de matières organiques, même faible, améliore la croissance et les activités des communautés bactériennes dans les zones salines. Une adaptabilité à la salinité est observée pour diverses populations de bactéries constituant des consortia ferri-réducteurs cultivables ou non, comportant au moins 4 à 5 populations identifiées. Ces consortia possèdent, pour certains des populations ferri-réductrices communes à l ensemble des conditions (salines vs non salines), des populations soit halotolérantes (Clostridium beijerinckii ; Bacillus sp. ; Oceanobacillus sp., Shewanella sp.), soit halophiles (Virgibacillus, Alkaliphilus metalliredigens, Bacillus megaterium), soit halosensibles, favorisant le maintien des activités dans des conditions de milieux variables. En Côte d Ivoire, les conditions de milieu semble plus réductrices avec la présence d une forte communauté bactérienne sulfato-réductrice (Desulfovribrio desulfuricans) et d une forte communauté bactérienne ferri-réductrice, majoritairement fermentaire (Bacillus sp.), qui contribuerait efficacement à la réduction et solubilisation du fer. L activité bactérienne ferri réductrice délétère en Côte d Ivoire mais bénéfique en Thaïlande, apparaît comme un paramètre et un indicateur de la qualité des sols de rizières.This work was performed to define the role of iron reducing bacteria (IRB) on the iron mobilization in two types of paddy fields presented different environmental problems. One is affected by salinity and received organic matter (Thailand) and the other by ferrous toxicity (Ivory Coast). Different approaches were adopted to characterize soil and water properties and determine in experiments populations and activities of IRB. Main parameters involved are salinity, rhizosphere, organic matter and iron bacterial reducing activities. Furthermore, the study of the structure of bacterial populations was done using molecular biology (PCR-TTGE). In Thai paddy soils, the results show that salinity limit bacterial communities proliferation. But the addition of organic matter improves bacterial growth and activities and remediates rice production. Bacterial populations observed in saline and non saline condition, presented halotolerant (Clostridium beijerinckii ; Bacillus sp. ; Oceanobacillus sp., Shewanella sp.), halophile (Virgibacillus, Alkaliphilus metalliredigens, Bacillus megaterium), or halosensitive characteristic, allowing the activity of bacterial communities in different medium conditions. In Ivory Coast paddy soils, the environmental conditions are more reducing with the presence of a large community of sulphate-reducing bacteria (Desulfovribrio desulfuricans). A large diversity of iron reducing communities, predominantly fermentative bacteria (Bacillus sp.), seems to contribute efficiently to iron reduction and solubilization. Iron reducing bacterial activity deleterious in Ivory Coast but beneficial in Thailand, appears as a parameter and indicator of the quality of paddy soil.NANCY1-Bib. numérique (543959902) / SudocSudocFranceF

Metallic Trace Elements (MTE) in soils and plant organs of some crop in periurban of Abidjan (Ivory Coast)

The quality of the plant production in periurban agriculture is subjected to question given the potential contamination of soils that can affect the crops. The levels of contamination of soils and vegetables by Metallic trace elements (MTE) as copper (Cu), zinc (Zn), cadmium (Cd) and lead (Pb) in the district of Abidjan, have been evaluated. Multi-sites survey of cropping areas of sweet potato and Hibiscus was conducted in three municipalities in Abidjan (Port-Bouët, Yopougon and Bingerville) in relation to the intensity of industrial and commercial activities. The site of Bingerville has been used as the reference site referring to the low activities. Soil samples (in 0-20 cm and 20 - 40 cm), combined with that of plants (leaf, stem, and root), and water were collected, transported in laboratory for analysis. The total amounts of MTE in soil, as well as the different fractions extracted were determined in addition to the respective concentration in plants (Hibiscus and Sweet potato). Toxic level of Pb (< 8 mgkg-1) was observed in the plant organs collected at Port-Bouët site indifferently to crops while lowest content of Pb (35.5 mgkg-1) was accounting for the soil of Yopougon (39.8 mgkg-1). A neutral pH of the soil has been considered more favorable to the contamination of plants in Pb on the polluted sites somewhat differing for extractable fractions. The acidity and small width of leaf as observed for Hibiscus, were identified as the control factors of crop contamination in periurban agroecosystems prone to Pb pollution. To strengthen the consistency of the knowledge, studies of the interaction between Pb and Zn as well as the translocation of Pb in the plants to tubers are suggested in the tropical ecosystems

Microbial Communities Involved in Fe Reduction and Mobility During Soil Organic Matter (SOM) Mineralization in Two Contrasted Paddy Soils

International audienceLowland rice fields of West Africa (Ivory Coast) and South Asia (Thailand) are affected by ferrous toxicity or salinity, respectively, and their soil waters contain large amounts of ferrous iron, depending on reducing irrigation condition and suggesting occurrence of bacterial reducing processes. To determine the involvement, dynamic and activities of bacterial communities in Fe(III) reduction and mobilization during anaerobic degradation and mineralization of soil organic matter (SOM), different experiments and analyses have been performed. Results demonstrated that the utilization of SOM as sole carbon, nutrient and energy sources favored the presence of large bacterial communities: facultative anaerobic and anaerobic bacteria, Fe(III)-reducing bacteria (FeRB) (fermentative and Fe respiring), sulfate reducing bacteria (SRB) which are involved in carbon, nitrogen, iron and sulfur cycling. The larger functional diversity is observed in the Ivory Coast paddy soils containing larger amounts of organic matter and sulfur compounds. These communities contained complementary populations (chemoorganotrophic, chemolitotrophic, aerobic, facultative anaerobic and anaerobic) that can be active at different steps of iron solubilization with simultaneous organic matter mineralization. Our results indicate that the pH controlled by bacterial activity, the nature much more than the content of organic matter, and consequently the structure and activity of bacterial communities influence significantly the availability and dynamic of iron in paddy fields which affect the soil quality

Restoration of the potentialities of a degraded ferralsol using cocoa bean teguments in Ahoue (South East, Côte d’ivoire)

This study consists of using the cocoa bean teguments as a means of sustainable production growth and environmental preservation. It aims to characterize the effects of the teguments on the chemical properties of a Ferralsol in Ahoué (Côte d'Ivoire). In an experimental block design of Fisher, three treatments of Cocoa bean teguments: T1 (10 t.ha-1), T2 (15 t.ha-1), T3 (20 t.ha-1) and one Control T0 have been set up with four repetitions. The main results show that the contribution of cocoa bean teguments has a positive effect on all the characteristics studied. The values obtained of the pH of the T0 and the T1, T2, T3 indicates, respectively 4.2; 5.4; 5.5 and 5.8. As regards the contents of the CEC, the values obtained give: 2.32; 7.2; 11.44 and 12.5 cmol.kg-1, respectively, for T0, T1, T2 and T3 treatments. As for the organic matter, the contents obtained indicate the following values: T0 = 12.56 g.kg-1; T1 = 26.49 g.kg-1; T2 = 35.09 g.kg-1 and T3 = 38.08 g.kg-1. The data corresponding to the sum of the captions oscillated between 4.5 and 10.5 cmol.kg-1 according to the treatments

Evaluation du Potentiel Mycorhizien des sols Pollués de la Décharge M’Ploussoue de Bonoua, Côte D’Ivoire

L’accumulation de substances toxiques telles que des éléments traces métalliques (ETM) dans les sols du site de la décharge de M’Ploussoue de Bonoua pourrait affecter la prolifération des microorganismes plus spécifiquement la sporulation et la germination des spores des Champignons Mycorhiziens à Arbuscules (CMA).C’est pour répondre à cette préoccupation que la présente étude s’est fixée pour but d’évaluer le potentiel mycorhizien des champignons indigènes des sols pollués de la décharge du Parc M’Ploussoué de Bonoua grâce à un test biologique avec Zea mays L. et Acacia mangium, comme des plantes pièges des microorganismes indigènes. Ainsi, après 45 jours de culture, le potentiel mycorhizien a été déterminé à partir de l’extraction desspores par tamisage humide, de la coloration des racines au bleu de trypan et du dénombrement des souches fongiques. L’analyse macroscopique des spores et des souches fongiques a révélé la présence du genre Glomus sp. (90%) appartenant à l’ordre des Glomales et également d’espèces peu spécifiques à acacia comme Aspergillus sp., Fusarium sp., Trichoderma sp. et Penicillium sp. L’examen microscopique des racines de Zea mays et de Acacia mangium a indiqué une fréquence (80 to 90%), une intensité (15 to 40%) de mycorrhization et un nombre d’arbuscules (87,5%) et de vésicules (12 to 100%) très importants sur le sol pollué. La formation des types de structures endomycorhiziens (vésicules et arbuscules) suggère la présence de champignons endomycorhiziens vesiculo-arbusculaires (CMVA) symbiotiques capables d’initier une symbiose et de favoriser un meilleur développement Acacia mangium malgré la pollution. Au su de ces résultats, les spores des CMVA de ce site pourraient être utilisées dans la remédiation du site. &nbsp; English title: Assessment of the Mycorrhizal Potential of Polluted Soils of M’Ploussoue Landfill in Bonoua, Côte D’Ivoire The accumulation of toxic substances such as metallic trace elements (TME) in landfill soils of the M'Ploussoue site in Bonoua could affect microorganisms proliferation specifically the sporulation and germination of spores of Arbuscular Mycorrhizal Fungi (AMF). To address this concern, this study was to assess the mycorrhizal fungi indigenous potential of polluted soils of M’Ploussoue landfill in Bonoua by a biological test with Zea mays L. and Acacia mangium Wild, as an host plants in trap culture of indigenous mycorrhizal fungi. After 45 days of culture, the mycorrhizal potential was determined through the extraction of the spores by soil wet sieving, the roots clearing with trypan blue and the count of fungal strains. The macroscopic analyzis of the spore and fungi strains revealed the majoritory presence of Glomus spp. (90%) belonging to the Glomal orderand also the presence of nonspecific fungi especies to acacia as Aspergillus spp., Fusarium spp., Trichoderma spp. and Penicillium spp. The microscopic examination of Zea mays and Acacia mangium roots indicated frequency (80 to 90%), intensity (15 to 40%) and arbuscule contents (87.5%) and vesicles (12 to 100%) are very important in polluted soil. The formation of typical endomycorrhizal structures (vesicles and arbuscules) suggests the presence of symbiotic vesiculo-arbuscular endomycorrhizal fungi (VAMF) able to promote better Acacia mangium development despite soil pollution. Based on these results, the spores of VAFM fungi from this site could be used in the remediation of the site

Restoration of the potentialities of a degraded ferralsol using cocoa bean teguments in Ahoue (South East, Côte d’ivoire)

This study consists of using the cocoa bean teguments as a means of sustainable production growth and environmental preservation. It aims to characterize the effects of the teguments on the chemical properties of a Ferralsol in Ahoué (Côte d'Ivoire). In an experimental block design of Fisher, three treatments of Cocoa bean teguments: T1 (10 t.ha-1), T2 (15 t.ha-1), T3 (20 t.ha-1) and one Control T0 have been set up with four repetitions. The main results show that the contribution of cocoa bean teguments has a positive effect on all the characteristics studied. The values obtained of the pH of the T0 and the T1, T2, T3 indicates, respectively 4.2; 5.4; 5.5 and 5.8. As regards the contents of the CEC, the values obtained give: 2.32; 7.2; 11.44 and 12.5 cmol.kg-1, respectively, for T0, T1, T2 and T3 treatments. As for the organic matter, the contents obtained indicate the following values: T0 = 12.56 g.kg-1; T1 = 26.49 g.kg-1; T2 = 35.09 g.kg-1 and T3 = 38.08 g.kg-1. The data corresponding to the sum of the captions oscillated between 4.5 and 10.5 cmol.kg-1 according to the treatments

Hazardous Impacts of Open Dumpsite of Municipal Solid Wastes on Soil: Case of M’Ploussoue Park Dump at Bonoua in Ivory Coast

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