Global Advanced Research Journal of Agricultural Science (GARJAS) ISSN: 2315-5094
September 2015 Vol. 4(9): pp. 517-532
Copyright © 2015 Global Advanced Research Journals

Full Length Research Paper

Identification and Improving Antibiotic Production by Some Bacteria Isolated From Egyptian Soil

Mohamed T. Shaaban¹, M. Attia², Eman I. Mowafy²*, Azza Sh. Turky² and Nemat M. Awad²

¹Botany Dept. Faculty of Sci. Minufiya University 

²Agricultural Microbiology Dept., National Research Centre, 33 El-Bohouth St., (former El- Tahrir St.,) Dokki,Giza, Egypt. Postal Code: 12622.

*Corresponding Author’s Email: eman_mowafy2007@hotmail.com;

Tel: +201002940449, 0226335595; Fax: 0202 6203731.

Accepted 16 September, 2015

Abstract

The three isolates (SOF12, AMF11 and SMF4) showed highly capability for antimicrobial activity against all the tested pathogenic bacteria with high potential inhibitory activity against yeast and two filamentous plant pathogenic fungi were prescreening studies for bioassay against crude extracts and assayed for their minimal inhibitory concentrations (MIC). The result showed that, crude extract tested positive in bioassay against the all tested pathogenic bacteria while different between them. MIC values ranging from 0.0625 to 5 mg/ml. 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 identified Bacillus megaterium TDB-13,Bacillus licheniformis DV7 and Bacillus subtilis 003141, respectively. 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 the first to the 9 day 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 and asparagine, while B. licheniformis, starch and glycerol, but B. subtilis glycerol. The asparagine was observed as the best nitrogen source for all the strains.

Keywords:  Antimicrobial agent, Bacterial isolates, growth factors, 16S rRNA gene.