Root-knot nematodes (RKNs) are one of the major constraints of vegetable cultivation worldwide. Chemical nematicides, the primary management tool for over 50 years, have a negative impact on the environment and the ineffectiveness after prolonged use. Biological control using eco-friendly rhizosphere bacteria antagonistic to nematodes is one of the alternative approaches. The objective of this study was to improve the nematicidal activity of Bacillus amyloliquefaciens subsp. plantarum SA5 and Lysinibacillus sphaericus Amira strain against RKN Meloidogyne incognita, using the protoplast technique. Their fusants were tested for their chitinase and nematicidal activity using bioassay and greenhouse experiments. The selected fusants from the two bacterial strains were more effective in killing M. incognita J 2 under laboratory conditions. Percentage mortality after 24 h of exposure were 70. 85, 84.69, 95.56, 94.99, 100, and 89.46% due to the parental strains B. amyloliquefaciens and L. sphaericus and the fusants Bas3, Bas6-2, Bas8, and Bas11, respectively. There was a positive correlation between the chitinase production and the nematicidal effect of the bacterial strains. Under greenhouse conditions, Bas8 which produced the highest amount of chitinase induced the greatest reduction in nematode counts and gave the best results in shoot length and fresh and dry weights as compared to control. Chitinase production of fusant was much higher under solid-state fermentation (SSF) than submerged fermentation conditions. The recorded chitinase produced by B. amyloliquefaciens, L. sphaericus, and Bas8 were 0, 1393, and 3399 units (μg NAG/ml enzyme/h), respectively, under solid-state fermentation and 90, 85, and 143 units (μg NAG/ml enzyme/h), respectively, under submerged fermentation conditions. Protoplast fusion was a powerful technique in improving nematicidal activity. Chitinase production is an important factor in improving the nematicidal activity of such microorganisms. The obtained improved fusant could be used as a biological control agent for M. incognita.

Integrated regimens were conducted at Kafre-Hakim village to evaluate the efficacy of different agents in controlling root-knot nematode Meloidogyne incognita and root rot disease infecting eggplant cv. Baladi and their effects on yield production. The treatments used were either single or combined treatments of (1) fungal filtrate of Trichoderma harzianum; (2) Bacillus thuringiensis; (3) NPK, inorganic fertilizer; (4) Oxamyl, a chemical nematicide; and (5) chicken manure. The present study emphasized that all treatments exhibited variable potential activities against the rootknot nematode and root rot disease incidence and improved eggplant production. The most nematode and root rot bio suppressive agent was chicken manure single treatment. Although NPK alone showed remarkable increase in eggplant yield, the data generally showed that other combined treatments gave better results in improving yield production than single treatments. Integration of chicken manure with NPK, T. harzianum or B. thuringiensis to improve the disease-control efficacy and crop yield was more economically as well as environmentally acceptable.

Background: Peanut (Arachis hypogaea L.) is considered one of the most important legume and oil crops in Egypt. Root-knot nematodes Meloidogyne spp. is the most damaging nematodes of peanut. Losses can exceed 50% in severely infested soil. Application of nematicides is one of the primary strategies in controlling plant-parasitic nematodes. The nematicides are proven to be hazardous to the environment. A promising alternative is the use of microorganisms antagonistic to plant-parasitic nematodes. Some microorganisms that can grow in the rhizosphere such as Azotobacter and Bacillus bacteria and fungi, e.g., Tricoderma and Paecilomyces represent the front line of defense for roots against nematode attack and ideal for use as biocontrol agents. Objectives: The main aim of this study was to evaluate the efficacy of application of yeast fungus Saccharomyces cerevisiae singly or combined with fusant Bas 8; (Bacillus amyloliquefaciens and Lysinibacillus sphaericus Amira strain); Bacillus thuringiensis strain code K, Trichoderma harzianum, or Paecilomyces lilacinus to control the root-knot nematode Meloidogyne javanica infecting peanut plant cv. Giza 6, and to estimate their yield under field conditions. Results: Compared to the untreated control, all treatments exhibited variable potential inhibitory activities against root-knot nematode M. javanica and enhanced peanut yield production. The most nematode suppressive treatment was the single treatment of Saccharomyces cerevisiae, followed by T. harzianum either singly or combined with the yeast. Moreover, data indicated that application of the combined treatment of yeast plus T. harzianum gave the best results in improving peanut production, plant growth parameters, and seed nutrient contents. Conclusion: It was concluded that integrated application of microorganisms could enhance peanut production and reduce the need for either chemical fertilizers or nematicides.

Background Plant parasitic nematodes create serious threat to crop production. In Egypt root knot nematode, Meloidogyne spp. has been considered to be a limiting factor in the production of most crops of which the Peanut (Arachis hypogaea L.) is an important legume and oil crop. Therefore, management of root knot nematodes Meloidogyne spp. is an obligatory challenge. Microbial organisms are extensively used as eco-friendly tools for controlling plant parasitic nematodes as alternative to chemical nematicides. The effectiveness of the commercial bacterial bio-fertilizers NPK containing Bacillus polymyxa, B. circulance, B. megaterium, Pseudomans spp.; the nitrogen fixative bacteria Azotobacter chroocoocum and the bacterial isolate NRC211 were evaluated against the root knot nematode, Meloidogyne javanica infecting peanut plants under field conditions. Identification of the bacterial isolate was made through PCR amplification and sequencing of 16S rDNA gene. Results Sequencing of 16S rDNA gene revealed that the bacterial isolate NRC211 had 100% similarity with Bacillus wiedmannii strain FSL W8-0169 16S ribosomal RNA. This Bacillus was recorded for the first time under accession number LC626774 on GenBank data base as B. wiedmannii NRC211. Recorded data revealed that all the tested treatments whether single or combined in soil naturally infested with M. javanica, resulted in variable significant reduction in the nematode reproductive parameters with a considerable increase in crop production and oil content of peanut plant. These results were improved by increasing the frequency of application of the bio-agents. In this respect the repeated combined treatment of A. chroococcum and B. wiedmannii NRC211 treatment overwhelmed all other treatments in decreasing nematode reproductive parameters with percentage reductions of 94.8, 79.0 and 80.1% in M. javanica juveniles in soil, galls and egg masses, respectively. This was associated with slight increase in peanut oil content than the untreated control. The repeated combined treatment of NPK plus A. chroococcum produced the highest increase 608.7%, and 72.7% in crop production and plant growth parameters, respectively than the control. While, the oil content in this treatment was increased up to 47.4 g/kg. Conclusion It was concluded that B. wiedmanni NRC211 is an eco-friendly bio agent that can be applied with other commercial microbial bio-fertilizers in bio-integrating programs for controlling M. javanica infecting peanut plants.

Background Eggplant (Solanum melongena) is one of the most popular vegetable crops in Egypt. It is affected by a wide range of pests; prominent among them is root-knot nematode (RKN) Meloidogyne spp. which constitutes a major group of plant-parasitic nematodes causing great economic losses worldwide especially in Egypt. Main body The present investigation was performed under greenhouse conditions to evaluate the potentials of 3 growth-promoting bacteria, Azospirilum brasilense, Azotobacter chroococcum, and Bacillus subtilis, as well as chitosan for the control of the nematode Meloidogyne incognita causes root-knot disease of eggplant cv. Baladi. All treatments reduced (p ≤ 0.05) the nematode population in soil and roots as well as enhanced the plant growth parameters of eggplant remarkably than the control. The applied treatments varied in their efficacy against the plant nematode infection in correspondence to the time of application. The recorded results demonstrated that maximum reduction in J2 in soil, egg mass/root, and eggs/egg masses were obtained by treating the soil with Bacillus subtilis followed by Azospirilum brasilense and Azotobacter chroococcum. Also, chitosan resulted in high reduction in root galls compared to control treatment. Conclusion The use of plant growth-promoting rhizobacteria, Azospirilum brasilense, Azotobacter chroococcum, Bacillus subtilis, and chitosan achieved efficient control to Meloidogyne incognita and consequently increase eggplant growth parameters under greenhouse conditions. The present results suggested introducing such rhizobacteria in integrated nematode management program.