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Title: Biochemical basis of repression of mineral phosphate solubilization MPS phenotype in rhizobial species
Researcher: Iyer, Bhagya
Guide(s): Shalini, Rajkumar
Keywords: Biochemistry
Biology and Biochemistry
fertilizing agent
Life Sciences
tricalcium phosphate
University: Nirma University
Completed Date: 2020
Abstract: The present study focuses on investigating the mechanism of phosphate solubilization newlinein nitrogen fixing rhizobia, as such strains may provide dual advantage to the plants by newlineproviding fixed N and free P. Td3 and SN1 are phosphate solubilizing nodule rhizobia of newlineCajanus cajan and Sesbania rostrata respectively. They solubilized 423and#956;g/mL and 428and#956;g/mL newlinephosphate from tricalcium phosphate through secretion of 19.2mM and 29.6mM gluconic acid newlinerespectively, when grown in 100mM glucose. However, 90% and 80% reduction in phosphate newlinesolubilization coupled to production of 40mM (Td3) and 28.2mM (SN1) gluconic acid was newlineobserved when the two isolates were grown in 100mM glucose+50mM succinate (repression newlinemedium). Our results illustrated the role of succinate irrepressible glucose dehydrogenase newline(gcd) in phosphate solubilization and the role of succinate: proton symport in succinate newlinemediated repression of phosphate solubilization in these rhizobia. Calcium ion newlinesupplementation reduced the 88% and 72% repression in P solubilization to 18% and 9% in newlineTd3 and SN1 respectively coupled to a reduction in media pH from 6.8 to 4.9 in Td3 and 4.8 newlinein SN1. Hence, succinate mediated repression of P solubilization had no genetic basis and was newlinepurely due to the biochemical interplay of protons and other cations, which was in contrast to newlineother reported rhizobial strains, in this regard. newlineStudying the genome of Td3 was important as it had succinate irrepressible glucose newlinedehydrogenase and could not solubilize phosphate in glucose+succinate conditions, in spite of newlinegluconic acid production which was enough to achieve mineral phosphate solubilization. This newlineis in contrast to the other explored rhizobial phosphate solubilizers. Rhizobial isolates newlinesequenced so far are known to lack components of the direct glucose oxidation pathway and newlinecannot produce gluconic acid on its own. Here, we present the genome sequence of newlineRhizobium sp. Td3 that comprises of a single chromosome of size 5,598,346 bp (5.6 Mb) with newlineno symbiotic plasmid. Rhizobium leguminos
Appears in Departments:Institute of Science

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11. chapter 2.pdf1.85 MBAdobe PDFView/Open
12. chapter 3.pdf284.15 kBAdobe PDFView/Open
13. chapter 4.pdf6.59 MBAdobe PDFView/Open
14. chapter 5.pdf135.84 kBAdobe PDFView/Open
15. chapter 6.pdf504.8 kBAdobe PDFView/Open
1.title.pdf26.78 kBAdobe PDFView/Open
2. certificate.pdf442.27 kBAdobe PDFView/Open
3. declaration.pdf446.97 kBAdobe PDFView/Open
4. acknowledgements.pdf1.84 MBAdobe PDFView/Open
5. abstract.pdf92.58 kBAdobe PDFView/Open
6. contents.pdf97.57 kBAdobe PDFView/Open
7. list of figures.pdf91.11 kBAdobe PDFView/Open
80_recommendation.pdf75.94 kBAdobe PDFView/Open
8. list of tables.pdf86.26 kBAdobe PDFView/Open
9. abbreviations.pdf90.43 kBAdobe PDFView/Open
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