Engineering of mutants of Anabaena PCC7120 (cyanobacterium) constructed by DNA-plasmid transfer and UV-radiation resistant to the herbicide Diuron capable of ammonia production

Iak, Tiwari Dn, Al-Thani Rf
Ten mutants of Anabaena PCC7120 were successfully constructed to express two genetic traits, ammonia production and the resistance to the Diuron herbicide, using transposon induced mutagenesis and UV-radiation. The ranges for heterocyst frequency and ammonia production of mutants were 4.2%-6.8% and 2.3-6.6 µmol mg dry wt-1 h-1 respectively. The herbicide-resistance threshold for all mutants was 2.0 mg L-1 , above which the mutants started to decline in health as observed microscopically. The
more » ... oscopically. The dry weight of the mutants reached 300-400 mg L-1 with growth patterns similar to those of the wild-type after 20 days of growth in a batch culture in the presence of Diuron. In contrast, the addition of herbicide to the wild-type has led to a drastic reduction in O2-evolution followed by cellular vaculation, breakdown of filaments and cell death within 24 h (data not shown; microscopic inspection).