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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: Microbial cultures are extensively used as environment friendly ways for biological control of parasitic pests, including the root-knot nematodes, alternative to the use of chemical nematicides. The present study was conducted to isolate some lytic rhizobacteria and examine their nematicidal activity against Meloidogyne incognita J 2 mortality and egg hatching in in vitro test. Results: Lytic Rhizobacteria were isolated from soil samples adhering to tomato plant roots from different localities at Giza governorate, Egypt. Six bacterial isolates, exhibited high efficacy against root-knot nematodes, were identified based on the analysis of the 16S rRNA gene sequence as Pseudomonas aeruginosa, Paenibacillus polymyxa, Lysinibacillus sphaericus, Bacillus cereus, Bacillus subtilis, and Achromobacter xylosoxidans. These strains showed high production of chitinase, chitosanase, and protease using colloidal chitin and soluble chitosan as carbon sources. Two strains, Paenibacillus polymyxa and Bacillus subtilis, produced the highest levels of chitinase in the media. Except for Pseudomonas aeruginosa, all the bacterial strains produced high levels of chitosanase. Conclusion: The results revealed that high amounts of protease were, however, secreted by Pseudomonas aeruginosa as compared to the other strains. In in vitro tests, all the bacterial culture filtrates potentially displayed nematicidal effect in M. incognita egg hatching and an obvious increase in J 2 mortality as compared to control. Paenibacillus polymyxa caused 100% juvenile mortality followed by Bacillus subtilis 97.25%, Bacillus cereus 94%, Achromobacter xylosoxidans 93%, Lysinibacillus sphaericus 92%, and Pseudomonas aeruginosa 84.29% after 48 h of exposure, as compared to control.

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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.

A gene encoding chitinase from B. subtilis has been isolated after optimization of PCR conditions. It was cloned with two different prometers, T7 promoter of the pJET1.2/blunt cloning vector and the SP6 promoter of pGEM®-T Easy vector. After transforming E. coli DH5α, two transformants were selected, CHI-NRC-4 from the first vector and T-CHI-NRC-6 from the second vector, and used for further studies. The complete CDS sequence of chitinase gene was determined and submitted to GenBank with the accession number KX268692.1. Culture supernatants of E. coli (CHI-NRC-4) and E. coli (T-CHI-NRC-6) were investigated for their inhibitory effect on M. javanica egg hatch under laboratory conditions. Result showed up to 96% inhibition in egg hatching due to both E. coli transformants as compared to control which reflect the same expression efficiency of both used prometers. A greenhouse experiment was carried out to evaluate the nematicidal effect of culture supernatants of the two transformts E. coli (CHI-NRC-4) and E. coli (T-CHI-NRC-6) against M. javanica infected eggplant. Obtained results showed a significant reduction in nematode population in soil and roots and enhancement in eggplant growth parameters as compared to control.