LAPORAN AKHIR PROGRAM RISET INSENTIF 2010 - KM Ristek

·..
SUMMARY
Genetic engineering of superior Azospirillum for lowering demand of chemical fertilizer of
30% of N and 15% P from standard application for lowland rice. Riyanti, E.l., D.N.
Susilowati, and Toto Hadiarto. Modern agriculture is highly depending on chemical
fertilizers i.e. N, P and K. The use of superior engineered Azospirillum sp which has multi
functions: fixing N 2 , solubilize P and producing Indole Acetic Acid (IAA) hormone could
substitute chemical fertilizers application. Previous result (2009), 22 chosen isolates have
been determines as multi function Azospirillum sp, capable of fixing N 2 , solubilizing P, and
producing plant growth hormone lAA. Three isolates (Aj 18.3.1, Aj 5.2.5.1, and Aj
Bandung 6.4.2.1) have been chosen among 22 isolates which have superior performances
for nitrogenase production, capability for P solubilization and production of lAA. These
three isolates have been monitored for the capability of P solubilization in liquid culture
compared to conunercial strain, and have been identified using 16S rDNA. Based on the
result in 2009, isolate Aj Bandung 6.4.1.2 have been chosen for material in 2010. The
objectives of this research are: strain improvement using EMS mutagenesis, investigation
the effect of mutation to the nitrogenase activity and the production of lAA, and the
stability of mutans. Mutagenesis using EMS at various concentration (0, 0,5, 1, 1,5 and ::::
%) at various time of incubation time (0, 15, 30, 45, 60 and 90 minutes) have been
performed. Concetration of 1.5% of EMS with the incubation time at 45 minutes sho\\·s the
most suitable combination for mutagenesis proses for this isolate. About 138 mutans have
been chosen according to the clear zones which are developed. The killing curves of this
isolate have also been determined. Secondly, the mutagenesis have influenced on the
production of nitrogenase and lAA at various levels. The increase on nitrogenase levels is
not accompanied by the increase of IAA productions" it may due to the biochemistry
balance on the cells. Both the two chosen mutans (AzM1.7.2.12 and AzM 3.7.1.14) have
stable characters on nitrogenase production, lAA production and capacity on solubilizing P
compared to the wildtype (Aj Bandung 6.4.1.2).
Key words: Azospirillum, nitrogenase, P solubilizer, lAA, mutagenesis
vi