الفهرس 
1. Introduction.Only 14 pages are availabe for public view
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Abstract
1) The 20 soil samples were collected from different locations of Egypt, including calcareous soil from Borg El-Arab and El-Ameria, sandy loam soil from South El-Tahrir and Ismailia, salt affected soil from Sedi Salem and Kafr El-Sheikh, alkaline soil from El-Tal El-Kebeer and silty clay loam soil from Tanta, Sheben El-Kom and El-Mansora. On the whole 112 bioactive bacteria isolates were obtained on the basis of clear zones suspected of showing antagonistic activities using Luria-Bertani (LB) media. 2) A total of 28 isolates of bacterial were selected as the representative strains on the basis of their origin and antimicrobial activity for detailed study. 3) Among the 18 new active isolates were selected based on inhibition zone over 25 mm and hyphal growth inhibition over 90% 4) Only three bacterial isolates SOF12, SMF4 and AMF11 inhibited all the tested microorganisms with high potential inhibitory activity against both filamentous fungi. 5) According to the types of crude extract BEA provided the highest active extracts (13/18, 72.22%) followed by BH (9/18, 50.00%), and BPE (8/18, 44.44%), respectively 6) According to the ethyl acetate crude extract from isolate SOF12 showed the highest active extracts followed by AMF11 and SMF4. On the other hand, SMF4 showed less and smaller zone of inhibition compared to the other two bacterial strains (SOF12 and AMF11). 7) Isolate SOF12 showed highest activity against S. aureus and Ps. aeruginosa with an MIC of 0.0625 μg/ml whereas the MIC for MRSA and E. coli was 0.125 μg/ml. 8) ) Isolate AMF11showed good antimicrobial activity against all the test organisms used especially the S. aureus, E. coli and Ps. aeruginosa, with MICs of 0.125 μg/ ml but least activity against MRSA with MIC of 0.25. 9) Isolates SMF4 was also strongly inhibitory with values of 0.0625 μg/ml against E. coli while least activity against Ps. aeruginosa with MIC of 0.25. 10) Based on it’s morphological and microscopy characteristics as well as 16S rRNA sequence analysis, the three isolates designated as SOF12, AMF11 and SMF4 were identified as Bacillus megaterium QST3.7, Bacillus licheniformis DV7 and Bacillus subtilis CHB1-3, respectively. 11) To study the effect of some growth factors on the production of antagonistic bacteria metabolites against selected human, plant pathogenic bacteria and plant pathogenic fungi and yeast. The results showed that the antimicrobial activity of the metabolites increased generally from zero to 54 hours of incubation, the optimum temperature for maximum activity by B. megaterium and B. licheniformis was observed at 30°C while B. subtilis at 25°C, the optimum pH for B. megaterium and B. licheniformis was 7 whereas B. subtilis at pH 8, the best carbon sources for B. megaterium was starch, while B. licheniformis, starch and glycerol, but B. subtilis glycerol. The asparagine was observed as the best additional nitrogen source for all the strains. 12) It is obvious that the exponential phase of growth lasted at 54 h for B. megaterium, B. licheniformis and B. subtilis of incubation period whereas the stationary phase was during 48-54h for all the strains.. 13) The highest value of specific growth rate (μ) was recorded by B. megaterium (0.0089 h-1) followed by B. licheniformis (0.0081 h-1). These results were reflected in multiplication rates (MR) and doubling times (td) to be 0.011 h-1, 86.62 h-1 for B. megaterium and 0.012 h-1, 85.58 h-1 for B. licheniformis respectively. The highest figure of number of generation was recorded by B. megaterium and the lowest value was recorded by B. licheniformis. 14) In prescreening studies, the selected strains were cultivated on small scale, the resulting culture broth of each of the strain was centrifuged and the supernatants were extracted with ethyl acetate to obtain the crude extracts. The crude extracts of individual strains were screened biologically and chemically 15) In biological screening the activity of the extracts was determined against a set of test organisms including, plant pathogen bacteria (Agrobacterium tumefaciens and Erwinia carotovora), Gram-negative bacteria (Escherichia coli and P. aeruginosa) and Gram-positive (Staphylococcus aureus and Methicillin-resistant Staphylococcus aureus (MRSA), plant pathogen fungi (Fusarium solani and Fusarium oxysporum) and two yeast (Candida albicans and C. neoformans). Antimicrobial activities against almost all the test organisms were observed, however the most promising activities were exhibited by the B. megaterium. 16) In chemical screening the crude extracts obtained from the strains were analyzed by TLC (Thin Layer chromatography). Thin-layer chromatography of the ethyl acetate fraction revealed three separate bands when viewed under UV light at 254 nm. Results of thin layer chromatography for the 3 bacteria strains are shown in Fig. 3. The Rf values for B. megaterium, B. licheniformis and B. subtilis were 0.45, 0.52 and 0.40 respectively. The eluate from the upper band inhibited the growth of all tested microorganisms. The middle and lower bands did not inhibit the growth of any of the test organisms. 17) On the basis of the metabolic profiles (metabolic fingerprint) obtained by chemical screening and the biological activities exhibited by each of the selected strain, B. megaterium was selected as the competent strains and were cultivated on larger scale (20-50 liter) for the identification of the antimicrobial compounds produced by them. In preparative screening the strain was cultivated as shaking cultures on an orbital shaker or in lab fermenters at 30°C for 3 days. In each case after harvesting, the culture broth was passed through a filter press to separate the cell mass from the liquid phase; the supernatant was extracted with ethyl acetate. The solvents containing the crude extracts were evaporated on a rotavapor and the few grams of dry crude extract of B. megaterium were obtained. The crude extract was fractionated on a silica gel column and the fractions were purified by preparative TLC, reverse phase silica gel columns and gel exclusion chromatography etc. The pure fractions obtained were identified by NMR spectroscopy (1H NMR and 13C NMR) along with data base searches (AntiBase, DNP etc). The B. megaterium yielded two pure compounds that were identified as 3-(methyl amino) phenol and 1-methyl-1H-indol-5-ol.