Ability of arbuscular mycorrhizal to protect tomato (Solanum lycopersicum) seedlings from Fusarium oxysporum

Present experiments were conducted in the microbiology laboratory, Department of Environmental and Agronomic Sciences and in a private nursery in the Tassoust region of Jijel during 2021 and 2022. This study was carried out on the use of strains of arbuscular mycorhizal fungi (Acaulospora sp. and Glomus sp.) as a means to control F. oxysporum effect. After 15 days of inoculation, several measurements of the lengths roots, stem and leaves were noted and symptoms of Fusarium disease were also recorded. The results revealed that F. oxysporum is a pathogen for tomato (Solanum lycopersicum L.) plants (super strain) variety, causing Fusarium disease of this host, which manifests by yellowing, wilting and necrosis of aerial parts, and reduced growth parameters in plants. Therefore, the disease incidence after 15 days of inoculation is estimated at 75 and 50% for (T1 and T3) respectively. In addition, our results revealed that the percentage of incidence was 100 and 25% respectively for T1 and T3 after 22 days. Whereas, the results showed that mycorhizal fungi are associated with the roots of tomato plants. They reduced the incidence rate of Fusarium disease by 50% (T3) and improved the growth of tomato seedlings (Super strain) which manifests itself by a vigorous root system and a very important development of the aerial parts. These results indicate that arbuscular mycorhizal fungi can effectively contribute to the ecological management of soil-borne fungal disease

Flow cytometry approach for studying the interaction between Bacillus mojavensis and Alternaria alternata

Tomato, Solanum lycopersicum is one of the most important vegetable crops consumed in Algeria. Tomato crops are often infected by Alternaria alternata, which causes early blight disease. Chemical pesticides are intensively used to protect this plant, which lead to environmental pollution that might endanger animal and human health. The main objective of this study is to select potential biocontrol agents from arid soil as an alternative to chemical products. The phytopathogenic fungus which was isolated from infested tomato leaves, stems and fruits cultured in Constantine-Algeria, was identified as Alternaria cf. alternata. Thirty five bacteria isolates were obtained from arid soil in the south of Algeria. Three of the isolates inhibited the growth of A. alternata. However, the most potent isolate, E1B3 reached a 75% inhibition rate. The molecular identification of this isolate showed that it was closely related to Bacillus mojavensis (KC977492). This strain does not produce chitinase, but does produce lipase, protease and lipopeptides. The interaction between A. alternata and B. mojavensis was investigated for the first time in this work by flow cytometric analysis. In conclusion, B. mojavensis strain was antagonistic to A. alternata which could possibly be exploited as a biopesticide in tomato crops management.Keywords: Tomato, Bacillus mojavensis, early blight, Alternaria alternata, flow cytometr

Production of Trichoderma harzianum (127a and 127b) spores by Fermentation (LF and SSF)

In order to produce a bio fungicide, two strains of Trichoderma harzianum (127a and 127b) were used.The results revealed that the mycelium multiplication of Trichoderma harzianum (127a and 127b) strains in liquid fermentation yielded a good mycelial mass (106 cells %252F ml), or the optimal conditions are a pH 5, a temperature of 30deg%253B C, and a medium of culture made of Malt extract and yeast extract. However, the more or less unfavorable conditions for the development of mycelium (FMS) favored the appearance of the spore form of our two antagonistic strains, which resulted in a smooth greenish powder at the end of the fermentation, on a solid medium

Oxidative and antioxidative responses to antimony stress by endophytic fungus Aspergillus tubingensis isolated from antimony accumulator Hedysarum pallidum Desf.

Antimony (Sb) is a toxic metalloid whose pollution has become a serious problem. However, studies on fungal endophytes resistant to antimony are virtually nonexistent. An endophytic fungal strain was isolated for the first time from the roots of Hedysarum pallidum Desf. which is a Sb accumulator Fabacea growing on mine cuttings. Experiments with high Sb increased concentrations (0, 5, 10, 20 and 30 mM Sb) were performed in order to assess the strain potential in contaminated environments bioremediation and to understand its Sb tolerance strategy. The isolated strain was identified as Aspergillus tubingensis MH189391 by morphological characteristics and phylogenetic analysis. It exhibited a minimum inhibitory concentration (MIC) of 500 mM Sb, i.e. 60,880 mg L−1, and maintained high amounts of biomass up to 30 mM Sb, i.e. 3652.8 mg L−1 of Sb. A stimulation of A. tubingensis growth and its antioxidant responses was observed at the level of 5 mM Sb, i.e. 609 mg L−1. Hydrogen peroxide (H2O2) and malondialdehyde (MDA) contents increased significantly (p < 0.05) with Sb treatments. Oxidative stress induced significant increases (p < 0.05) in antioxidant biomarkers such as proline, catalase (CAT), and superoxide dismutase (SOD), but it resulted in a significant decrease of peroxidase (POD) and ascorbate peroxidase (APX) activities. Proline, CAT, SOD, H2O2 and MDAwere significantly (p < 0.05) and positively correlated, which highlights their coactions in oxidative stress fighting. Results indicate that Aspergillus tubingensis has developed an important adaptation to excessive Sb concentrations and that it could be used in antimony-contaminated environments bioremediation

Biocontrol and Plant Growth Promotion Characterization of Bacillus Species Isolated from Calendula officinalis Rhizosphere

The phenotypic and genotypic diversity of the plant growth promoting Bacillus genus have been widely investigated in the rhizosphere of various agricultural crops. However, to our knowledge this is the first report on the Bacillus species isolated from the rhizosphere of Calendula officinalis. 15 % of the isolated bacteria were screened for their important antifungal activity against Fusarium oxysporum, Botrytis cinerea, Aspergillus niger, Cladosporium cucumerinium and Alternaria alternata. The bacteria identification based on 16S r-RNA and gyrase-A genes analysis, revealed strains closely related to Bacillus amyloliquefaciens, B. velezensis, B. subtilis sub sp spizezenii and Paenibacillus polymyxa species. The electro-spray mass spectrometry coupled to liquid chromatography (ESI-LC MS) analysis showed that most of the Bacillus isolates produced the three lipopeptides families. However, the P. polymyxa (18SRTS) didn't produce any type of lipopeptides. All the tested Bacillus isolates produced cellulase but the protease activity was observed only in the B. amyloliquefaciens species (9SRTS). The Salkowsky colorimetric test showed that the screened bacteria synthesized 6-52 μg/ml of indole 3 acetic acid. These bacteria produced siderophores with more than 10 mm wide orange zones on chromazurol S. The greenhouse experiment using a naturally infested soil with Sclerotonia sclerotiorum showed that the B. amyloliquefaciens (9SRTS) had no significant (P > 0.05) effect on the pre-germination of the chickpea seeds. However, it increased the size of the chickpea plants and reduced the stem rot disease (P < 0.05).These results suggested that the Bacillus strains isolated in this work may be further used as bioinoculants to improve the production of C. officinalis and other crop systems. © 2013 Association of Microbiologists of India

In Vitro and In Vivo Characterization of Plant Growth Promoting Bacillus Strains Isolated from Extreme Environments of Eastern Algeria.

This report is to our knowledge the first to study plant growth promotion and biocontrol characteristics of Bacillus isolates from extreme environments of Eastern Algeria. Seven isolates of 14 (50 %) were screened for their ability to inhibit growth of some phytopathogenic fungi on PDA and some roots exudates. The bacteria identification based on 16S r-RNA and gyrase-A gene sequence analysis showed that 71 % of the screened isolates belonged to Bacillus amyloliquefaciens and the rest were closely related to B. atrophaeus and B. mojavensis. Most of them had high spore yields (22 x 108-27 x 108 spores/ml). They produced protease and cellulase cell wall-degrading enzymes while the chitinase activity was only observed in the B. atrophaeus (6SEL). A wide variety of lipopeptides homologous was detected by liquid chromatography-electrospray ionization-mass spectrometry analysis. Interestingly, some additional peaks with new masses were characterized, which may correspond to new fengycin classes. The isolates produced siderophores and indole-3- acetic acid phytohormone. The greenhouse experiment using a naturally infested soil with Sclerotonia sclerotiorum showed that the B. atrophaeus (6SEL) significantly increased the size of the chickpea plants and reduced the stem rot disease (P < 0.05). These results suggest that these isolates may be used further as bio-inoculants to improve crop systems