Management of Tomato Foot and Root Rot (TFRR) by Biocontrol Agents with Emphasis on Factors Affecting Its Effectiveness
Springer eBooks, 2017
Management of tomato foot and root rot (TFRR) caused by Fusarium oxysporum f. sp. radicis-lycoper... more Management of tomato foot and root rot (TFRR) caused by Fusarium oxysporum f. sp. radicis-lycopersici (FORL) could be achieved by biological methods which represent an ecologically friendly strategy for the sustainable crop productivity. Among these biological methods, those using biocontrol agents (BCAs) such as bacteria or fungi able to antagonize soilborne plant pathogens or stimulate plant defenses, leading to plant protection against diseases, are of great promise (de Waard et al. Annu Rev Phytopathol 31:403–421, 1993; El-Tarabily et al. New Phytol 137:495–507, 1997; El-Tarabily. Can J Bot 84:211–222, 2006). They also represent a suitable alternative to the use of chemical pesticides. Some of these antagonistic microorganisms living in association with tomato roots showing also beneficial effects on the plant growth and nutrition are called plant growth-promoting rhizobacteria (PGPR). Consequently, PGPRs could also be used as biofertilizers and are considered as an alternative tool to chemical fertilizers. In tomato, many rhizobacteria were reported to suppress diseases caused by Fusarium and/or to lead to growth promotion and tomato yield enhancement. However, BCAs are confronted to ecological parameters that are important to be determined if one wishes to succeed in disease management. The present chapter describes tomato foot and root rot (TFRR) and main mechanisms deployed by BCAs used to suppress the disease (competition by siderophore production, antibiosis, or induced systemic resistance). As the success of biocontrol methods depends largely on biotic and/or abiotic factors, some abiotic factors influencing the biocontrol agent’s fitness as well as biotic factors represented by BCA interactions with either tomato plants or FORL are discussed in relation to the performance of BCAs either in greenhouse trials and agricultural fields.
In order to investigate the presence of thermo-tolerant rock phosphate (RP) solubilizing anaerobi... more In order to investigate the presence of thermo-tolerant rock phosphate (RP) solubilizing anaerobic microbes during the fermentation process, we used grassland as sole organic substrate to evaluate the RP solubilization process under anaerobic thermophilic conditions. The result shows a significant decrease of pH from 6.5 to 4.8, and solubilizing from 7 to 15.8% of the phosphorus from the RP in the reactors after 90 days of incubation at 45°C. In these conditions, the organic acids produced were qualitatively and quantitatively identified as: acetic, butyric and propionic acids. This biological RP solubilization is due to the presence of a single thermo-tolerant bacterium isolated and identified as Bacillus subtilis from the anaerobic reactors. This B. subtilis strain was shown to be able to solubilize RP in liquid cultures containing insoluble RP as sole phosphate source. The mechanisms involved in these weathering processes confirmed the production of organic acids which were identified and quantified. This study is expected to lead to the development of novel, non-polluting farming practices by entering in the formulation of novel multi-functional biofertilizer by inoculating this thermo-tolerant phosphate-solubilizing bacterium into agricultural wastes as a practical and environmental strategy.
Actinomycetes from Moroccan habitats: isolation and screening for cytotoxic activities
World Journal of Microbiology and Biotechnology, 2008
... Antitumor antibiotics produced by actinomycetes are among the most important cancer chemother... more ... Antitumor antibiotics produced by actinomycetes are among the most important cancer chemotherapeutic agents including members of the anthracycline, bleomycin, acti-nomycin, mitomycin and aureolic acid families (Rocha et al. 2001; Newman and Cragg 2004). ...
Microbial intervention improves pollutant removal and semi-liquid organo-mineral fertilizer production from olive mill wastewater sludge and rock phosphate
Bacteries actinomycetales rares productrices d'antifongiques : criblage, selection et etude taxonomique d'une souche active ; purification de l'antifongique elabore
Endophytes are the microorganisms that exist inside the plant tissues without having any negative... more Endophytes are the microorganisms that exist inside the plant tissues without having any negative impact on the host plant. Medicinal plants constitute the huge diversity of endophytic actinobacteria of economical importance. These microbes have huge potential to synthesis of numerous novel compounds that can be exploited in pharmaceutical, agricultural and other industries. It is of prime importance to focus the present research on practical utilization of this microbial group in order to find out the solutions to the problems related to health, environment and agriculture. An extensive characterization of diverse population of endophytic actinobacteria associated with medicinal plants can provide a greater insight into the plant-endophyte interactions and evolution of mutualism. In the present review, we have discussed the diversity of endophytic actinobacteria of from medicinal plants their multiple bioactivities.
Low availability of phosphorus (P) in both acidic and alkaline soils is a major problem for susta... more Low availability of phosphorus (P) in both acidic and alkaline soils is a major problem for sustainable improvement in wheat crops yield. Optimization of crops productivity can be achieved by increasing the bioavailability of P by phosphate solubilizing Actinomycetota (PSA). However, their effectiveness may vary with changing agro-climatic conditions. In this regard, a greenhouse experiment was conducted to assess the interaction inoculation of five potential PSA (P16-P18-BC3-BC10 and BC11) and RPs (RP1- RP2-RP3 and RP4) on the growth and yield of wheat crop in unsterilized P- deficient alkaline and acidic soils. Their performance was compared with single super phosphate (TSP) and reactive RP (BG4). The in-vitro tests showed that all PSA colonize wheat root and form a strong biofilm except Streptomyces anulatus strain P16. Our findings revealed that all PSA significantly improve the shoot/root dry weights, spike biomass, chlorophyll contents as well as nutrients uptake in plants fer...
In the context of intensive and sustainable agriculture, limiting soil degradation and the loss o... more In the context of intensive and sustainable agriculture, limiting soil degradation and the loss of organic matter has become an obligation to maintain food security. The use of organo-mineral fertilizer (OMF) products is an innovative technology that may solve the different challenges raised. This study aimed to evaluate the effect of various organo-mineral fertilizer (OMF) formulations on Zea mays agro-physiological traits, phosphorus (P)-related parameters, and water conservation during a 90-day pot experiment. The OMF formulations consisted of blending several doses of a stable OMWS compost (10 t /ha(OMF1), 50 t/ha (OMF2), or 100 t/ha (OMF3)) with different sources of mineral P, namely diammonium phosphate (DAP), rock phosphate (RP), or phosphate washing sludge (PWS), compared with separate applications. The results indicated that the effect of an OMF on the soil and plants was strongly dependent on the source of P used and the dose of OMWS compost. The best agronomic performance...
In Mediterranean countries, the olive oil industry generates the most important agro-industrial w... more In Mediterranean countries, the olive oil industry generates the most important agro-industrial wastewater, which results in the production of a highly toxic sludge following effluent decantation, thus endangering the environment. In this investigation, an optimized composting process via microbial inoculation is suggested as to alleviate the toxicity of olive mill solid sludge (OMS-Sludge) through addressing its high polyphenol and lipid content. The composting assay was carried out in a bioreactor using mixtures of sludge and green wastes, with or without microbial inoculation, namely: E1 (49% sludge + 49% green waste + 2% thermophilic Inoculum), and E2 (50% sludge + 50% green waste). After 4 months of composting the inoculation had affected at significantly (p < 0.05)pH, EC and total organic carbon degradation compared to control. Furthermore, HPLC analysis revealed that OMS-Sludge composting significantly diminished the polyphenol content (95% and 85% for E1 and E2, respectively), and the lipid content (90% and 81% for E1 and E2, respectively). More importantly, microbial inoculation resulted in a significant composting efficiency, which was corroborated by a decomposition rate 65% for E1 compared to 62% for E2. In-planta assays showed that both the lipid and polyphenol contents werestrongly correlated with the sludge phytotoxicity with respect to seed germination, which was demonstrated by a substantial improvement of the germination index of Cabbage (64.44%), Turnip (86.58%) and Cress seeds (120.85%). Overall, enhancing the composting process through microbial inoculation resulted in a significant alleviation of the initial mixture phytotoxicity, and proved to be an efficient strategy for OMS-Sludge valorization.
This study aims to select fungi isolates to reduce olive mill wastewater (OMWW) chemical oxygen d... more This study aims to select fungi isolates to reduce olive mill wastewater (OMWW) chemical oxygen demand (COD) and phenolic compounds (PC), as well as their genotoxicity effect. Treatment with mold, isolated by an innovative technique using phenolic compound-selective media, showed a reduction rate of about 4% for COD and 2% for PC during one month of incubation without optimization of the treatment conditions. Whereas this percentage reached 98% and 96% for COD and PC, respectively, after only 12 days of treatment, when the C:N ratio was adjusted to 30 by adding urea as a nitrogen source at 150 rpm agitation speed. Genetic sequence homology of the most efficient mold isolate showed 100% similarity to Penicillium chrysogenum. High-performance liquid chromatography analysis of phenolic extracts of untreated OMWW showed the presence of five compounds—hydroxytyrosol at 1.22 g.L−1, tyrosol at 0.05 g.L−1, caffeic acid at 0.16 g.L−1, p-coumaric acid at 0.05 g.L−1 and oleuropein at 0.04 g.L−...
The present study was conducted to determine the antibacterial and antifungal potential of actino... more The present study was conducted to determine the antibacterial and antifungal potential of actinomycetes isolated from soil samples collected from two different locations of Punjab, India. The actinomycetes isolates showed various types of color pigments like pink, yellow, orange, red and brown which may have potential use in industries. Out of 23 actinomycetes isolates, 7 of them showed significant inhibition of different Gram positive and Gram negative bacteria and also some fungi. Actinomycetes isolate no. A4 inhibited Klebsiella pneumonia and Salmonella enterica typhimurium efficiently. Actinomycetes isolate no. A5 inhibited E. coli, Staphylococcus aureus, Klebsiella pneumonia, Salmonella enterica typhimurium and the fungi Alternaria alternata and Trichodermaviride. The crude antimicrobial compound from the best isolates A4 and A5 were obtained by ethyl-acetate extraction and the MIC against two different bacteria Klebsiella pneumonia and Salmonella enterica typhimurium were 15µg/ml and 12µg/ml respectively. Determination of the nature of the antimicrobial compound by TLC analysis indicated that the compound may be alcohol, phenol or steroid in nature. The antimicrobial compound obtained from isolate A5 was stable even above 60°C and in the presence of proteinase K enzyme (5mg/ml). The results showed that isolate A5 which produced dark orange colour pigment has excellent antimicrobial characteristics with very low MIC value and stability at high temperatures and high concentration of proteinase K.
Application of Olive-Mill-Wastewater-Compost in Combination with Symbiotic Microorganisms Improves the Physiological, Biochemical Performance and Tolerance of Tomato (Solanum lycopersicum) Under Drought Stress
A discrete number of studies have been conducted on the effects of rhizobia (Rhz) inoculants, pho... more A discrete number of studies have been conducted on the effects of rhizobia (Rhz) inoculants, phosphorus (P) management, and combined application of Rhz and P fertilizer on the enhancement of grain legume yield across soils of Ghana and elsewhere. However, the extent to which the various inoculated Rhz strains, P application, and combined application of Rhz + P studies contribute to improving yield, performed on a comprehensive analysis approach, and profit farmers are yet to be understood. This study reviewed different experimental studies conducted on soybean (Glycine max (L.) Merr.), cowpea (Vigna unguiculata [L.] Walp), and groundnut (Arachis hypogaea [L.]) to which Rhz inoculants, P supplements, or Rhz + P combination were applied to improve the yield in Ghana. Multiple-step search combinations of published articles and multivariate analysis computing approaches were used to assess the effects of Rhz inoculation, P application, or both application of Rhz and P on yield variatio...
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