TANGGAPAN FISIOLOGIS RHIZOBAKTERI OSMOTOLERAN TERHADAP CEKAMAN KEMASAMAN DENGAN TOKSISITAS ALUMINIUM
| Main Authors: | , Jumailatus Solihah, , Prof. Ir. Triwibowo Yuwono, Ph.D., |
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| Format: | Thesis NonPeerReviewed |
| Terbitan: |
[Yogyakarta] : Universitas Gadjah Mada
, 2012
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| Subjects: | |
| Online Access: |
https://repository.ugm.ac.id/97683/ http://etd.ugm.ac.id/index.php?mod=penelitian_detail&sub=PenelitianDetail&act=view&typ=html&buku_id=54356 |
Daftar Isi:
- Some osmotolerant rhizosphere bacteria have been isolated from rhizosphere in Yogyakarta area. This study was aimed at analysing physiological and molecular responses of isolate Al-19 and M7b, previously isolated from Gramineae rhizosphere, to acidity stress. Biochemical characterisation and molecular analysis of 16S rDNA was performed to determine the position of isolates taxa. Physiological analysis includes observation of growth response to acidity, morphological changes and changes in composition of fatty acids under acidity stress in vitro. The results demonstrated that the acidity stress may result in some physiological and molecular responses of osmotolerant rhizobacteria. It was observed that the two isolates showed different response to acidity stress. M7b, which is a Gram-positive isolate, adapt to acidity stress by minimising the size of the cell, producing more and thicker capsules. Molecular response in the form of production of unsaturated fatty acids makes this isolate more resistant to acidic conditions, indicated by faster rate of growth under stress condition. Isolates Al19, which is Gram-negative bacteria, showed distinct responses to acidity stress. Under acidity stress, it demonstrated a longer lag phase than those under nonstress condition. Molecular response in the form of production of fatty acids with very long chains was observed as a means of defence against unfavourable conditions. Characterisation of the isolates M7b, based on biochemical characterisation and molecular identification demonstrated that these isolates showed a high similarity with Bacillus pumilus. Al-19 isolate was suggested to be a novel species, which have biochemical properties similar to genus Pantoea but the molecular nature (based on 16S rDNA gene sequences) is similar to Enterococcus flavescens.