Thirty bacterial isolates were tested on three different media for Poly-ß-hydroxybutyrate (PHB) production. The best bacterial isolates for producing PHB were screened and identified based on molecular biology; then, using three different alternative carbon sources (dried whey, sugar beet molasses and date molasses), physical properties were evaluated by Infrared (IR) spectrometry and Gas chromatography–mass spectrometry (GC-MS/MS) analysis. Our results showed that the best isolates identified based on molecular biology were Bacillus paramycoides MCCC 1A04098, Azotobacter salinestris NBRC 102611 and Brevundimonas naejangsanensis BIO-TAS2-2. The addition of sugar beet molasses to the medium of A. salinestris increased the cell dry weight (CDW), PHB concentration, PHB% and conversion coefficient (4.97 g/L, 1.56 g/L, 31.38% and 23.92%, respectively). The correlation coefficient values between PHB g/L and CDW g/L varied between very strong and moderate positive correlation. IR of the produced PHB from B. paramycoides and A. salinestris showed similar bands which confirmed the presence of PHB; however, B. naejangsanensis showed weak bands, indicating lower PHB concentration. The chemical composition obtained showed that the GC-MS of the PHB extracted represents 2, 4-ditert-butylphenol for B. paramycoides and isopropyl ester of 2-butenoic acid for both of A. salinestris and Brevundimonas naejangsanensis. Therefore, PHB produced by microorganisms can be considered a biodegradable polyester, and represents a promising technique for the development of eco-friendly and fully biodegradable plastics.

Using Bacillus species as bioagents for environmentally sustainable and economically viable plant disease management is a viable strategy. Thus, it is important to promote their use in agriculture. In this study, two Bacillus species were isolated from the rhizosphere of tomato plants, while three fungal species were isolated from samples of tomato plants that were infected with damping-off disease. The Bacillus strains were tested in vitro for their antagonistic activity against fungal species using a dual culture technique. In a greenhouse experiment, the effectiveness of applying antagonistic bacteria with soilborne fungal disease on induced damping-off of tomato (cv. Super Strain B) plants, their physiological attributes, antioxidant enzymes, mineral content, and yield under greenhouse conditions during the 2022 and 2023 seasons were determined. The fungal isolates were identified as Fusarium oxysporum KT224063, Pythium debaryanum OP823136, and Rhizoctonia solani OP823124, while the Bacillus isolates were identified as B. subtilis OP823140 and B. amyloliquefaciens OP823147 on the basis of the rRNA gene sequences. The dual culture test revealed that B. subtilis outperformed B. amyloliquefaciens in resistance to R. solani and F. oxysporum, which were recorded as 28.33 and 33.00 mm, respectivley. In contrast, B. amyloliquefaciens caused the highest antagonistic effect against tested P. debaryanum fungus. Additionally, in a greenhouse experiment, tomato plants treated with each of these antagonistic Bacillus strains significantly suppressed fungal disease, displayed improved plant growth parameters, had an increased content of photosynthetic pigments, antioxidants enzymes, and total phenols, and an increased macronutrient content and yield during the two growing seasons. In conclusion, effective applications of B. subtilis and B. amyloliquefaciens had the potential to mitigate damping-off disease, which is caused by F. oxysporum, P. debaryanum, and R. solani in tomato plants, while simultaneously promoting growth dynamics.

A field experiment was conducted to study the effect of three isolates of Cyanobacteria individually ((Nostoc punctiforme PQ870057, Nostoc parmelioides PQ864768 and Anabaena cylindrica PQ870058)) and a mixture of them with different ratios of nitrogen concentration(Zero,20,40 and 60 kg N/fed). This experiment was conducted in clay soil located in the center of Tanta, Gharbia Governorate. Cyanobacteria isolates showed. A significant increase in plant height, spike length, spike dry weight, number of spikes, grain yield, straw yield, and biological yield. The findings in unequivocally demonstrated that nitrogen fertilization had a major impact on the weight of grains. As a result, the wheat plant's all wheat wield and its components increased by up to 60 kg N/fed nitrogen fertilizer. The application of nitrogen increases all wheat wield and its components and enhances growth. Regarding the Cyanobacteria effect, notable variations found between the employed treatments. It was established by the data Cyanobacteria mixture produced the highest all wheat wield and its components value.