Efficiency of bacillus polymyxa for nitrogen fixation through mutation and conjugation [electronic resource].

Includes references.

The present study aimed to improve the ability of Bacillus po!ymyxa nitrogen f"txation through mutation induction which may be considered as a high quality biofertilizer. The study included two parts. The first part was conducted to induce mutants from the wild type of B. polymyxa strain using UV mutagen. Data revealed that number and percentage of mutant increased with increasing time of exposure to UV light. However, out of 775 colonies tested 19 proved to be mntants: one required glutamine, seven required alanine; one required aspartic, one required serine, one required histidien and eight revertant. In the second part, a pots experiment was performed to examine the efficiency of induced Bacillus polymyxa mutants conjugats and wild type in nitrogen fixation and thereafter on growth of maize plant. Results indicated significant increase in fresh weight of plants inoculated with Bacillus polymyxa wild type and some mutants compared with the control and the later were more effective than the wild type. The highest increase in fresh and dry weight were recorded in plants inoculated by some hybrids of mutants. Inoculation with Glu requiring mutant of Bacillus polymyxa and hybrids (GluxAlan, Alan x Alan, Alan xAsp, and SerxHis) significantly increased phosphorus content in maize plants and the maximum increase was attained in plants inoculated with Glu requiring mutants and hybrid (SerxHis). Some mutants and conjugants significantly increased nitrogen fixation compared with the wild type strain and the control.

Summary in Arabic.

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