Document Detail

Relationship between calcium and uroinic acids in the encystment of Azotobacter vinelandii.
MedLine Citation:
PMID:  235508     Owner:  NLM     Status:  MEDLINE    
Encystment of Azotobacter vinelandii (ATCC 12837) in modified Burk nitrogen-free medium (pH 7.0) containing 0.2 percent beta-hydroxybutyrate occurs optimally in 0.37 to 0.44 mM solutions of calcium ions. Suspension of cells in media deficient in calcium results in abortive encystment characterized by the release of viscous cyst coat material. Mature cysts rupture in ethylene glycol-bis-(beta-aminoethyl ether)-N,N'-tetraacetic acid, suggesting that calcium is a structural component of the cyst coat. Maximal stimulation of encystment by calcium ions occurs prior to the completion of the cyst exine or outer coat. The uronic acid composition of cyst components is dependent on calcium levels in the medium. Uronic acids account for 31.7 percent of the intine (inner coat) and 13 percent of the exine dry weight, and only mannuronic and guluronic acids are present in these fractions. These can be extracted as homo- and heteropolymeric sequence "blocks" characteristic of alginic acids. The polyuronic acid fraction of both the cyst coats contain approximately equal amounts of heteropolymeric (mannuronic acid/guluronic acid) blocks. The exine, however, is richer in polyguluronic acid and the intine is richer in polymannuronic acid. As a result, the mannuronic acid/guluronic acid ratio of the exine is lower than that of the intine. Slimes that form in abortive encystment are rich in polymannuronic acid and have a high mannuronic acid/guluronic acid ratio. A polymannuronic acid 5-epimerase is active in the mature cyst central body and the encystment culture fluid.
W J Page; H L Sadoff
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Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Journal of bacteriology     Volume:  122     ISSN:  0021-9193     ISO Abbreviation:  J. Bacteriol.     Publication Date:  1975 Apr 
Date Detail:
Created Date:  1975-07-01     Completed Date:  1975-07-01     Revised Date:  2009-11-18    
Medline Journal Info:
Nlm Unique ID:  2985120R     Medline TA:  J Bacteriol     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  145-51     Citation Subset:  IM    
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MeSH Terms
Azotobacter / cytology*,  enzymology,  metabolism
Calcium / pharmacology*
Carbohydrate Epimerases / metabolism
Cell Wall / metabolism
Hydrogen-Ion Concentration
Hydroxybutyrates / pharmacology
Magnesium / pharmacology
Spectrophotometry, Atomic
Uronic Acids / biosynthesis*
Reg. No./Substance:
0/Hydroxybutyrates; 0/Uronic Acids; 7439-95-4/Magnesium; 7440-70-2/Calcium; EC 5.1.3.-/Carbohydrate Epimerases

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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