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Transformation of organic rhizodepositions by rhizosphere bacteria and its influence on the availability of tertiary calcium phosphate
Author(s) -
Deubel Annette,
Gransee Andreas,
Merbach Wolfgang
Publication year - 2000
Publication title -
journal of plant nutrition and soil science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.644
H-Index - 87
eISSN - 1522-2624
pISSN - 1436-8730
DOI - 10.1002/1522-2624(200008)163:4<387::aid-jpln387>3.0.co;2-k
Subject(s) - chemistry , rhizosphere , bacteria , xylose , sugar , phosphate , pseudomonas fluorescens , food science , pantoea agglomerans , sorbitol , pisum , biochemistry , biology , fermentation , genetics
This study assesses the influence of saccharides in the rhizodeposition on the phosphate solubilizing ability of rhizosphere bacteria. Water‐soluble rhizodeposits were analyzed of 14 C‐labeled pea plants ( Pisum sativum , cv. ‘Grapis’) which were grown at two different levels of P‐nutrition. The sugars produced were fed in vitro either as single compounds or as synthetic mixtures to three bacterial strains and the ability of the bacteria to mobilize Ca 3 (PO 4 ) 2 was measured. The relative glucose proportion of pea exudates decreased under P deficiency while the content of galactose, ribose, xylose and fucose increased. In vitro feeding of single sugars and sugar mixtures showed that the ability of Pseudomonas fluorescens (PsIA12) to dissolve tertiary calcium phosphate was lower with pentoses and the mixed sugars of the P‐deficient plants than with glucose. On the other hand, the shifted sugar pattern observed under P deficiency increased the phosphate mobilization ability of Pantoea agglomerans (D5/23) and Azospirillum sp. (CC 322) considerably. This observation can only partly be explained by the acidification of the nutrient medium. Bacteria also produced different carboxylic anions depending on sugar supply. In addition to low‐molecular mono‐, di‐, and tricarboxylic acids which are known as P‐solubilizing substances, sugar acids also played an important role in cultures D 5/23 and CC 322.