Metabolic Pathways in Microorganisms
E. R. SQUIBB LECTURES ON
Presented at the Institute of Microbiology Rutgers. the State University of New Jersey
F. M. Strong, Topics in Microbial Chemistry, 1956
F. H. Stodola, Chemical Transformations by Microorganisms, 1957 V. H. Cheldelin, Metabolic Pathways in Microorganisms, 1960
Roger J. Williams
CHEMISTRY OF. MICROBIAL PRODUCTS
Metabolic Pathways in Microorganislns' By VERNON H. CHELDELIN Dzrector, Science Research Instztute Oregon State Unzverszty
NEW YORK . LONDON, JOHN WILEY & SONS, INC.
Copyright
©
1961 by John WiJey & Sons, Ine.
All rights reserved. This book or any part thereof must not be reproduced in
any form without the written permission of the publIsher. Library of Congress Catalog Card Number: 61-16617 Printed in the United States of America
In recognition of the importance of cooperation between chemist and microbiologist 'the E. R. Squibb Lectures on Chemistry of Microbial Products were established with the support of The Squibb Institute for Medical Research in 1955.
The lectures are presented annually in the fall at
the Institute of Microbiology, Rutgers, the State University of New Jersey, New Brunswick, New Jersey.
PREFACE
I am happy to have the opportunity to present this work on pathways of carbohydrate metabolism, which has been carried out, for the most part, in our laboratories (Science Research Institute, Oregon State University) during the last eight years. This work emphasizes heavily the peculiarities of metabolism that characterize the a 0
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." > Col > C-3,4) reflects the operation of the TCA cycle. The usefulness of the radiorespirometric experiments is revealed from the experiments in Fig. 2.9 on the utilization of gluconate by B. subtilis. Gluconate presumably cannot be converted directly back to glucose; its oxidation would seem to be obligatory by the pentose cycle, at least as far
53
EVALUATION OF METABOLIC PATHWAYS r-~~--~-r-------r-------------------------.~
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METABOLIC PATHWAYS IN MICROORGANISMS
as the formation of triose phosphate or fructose-6-phosphate. Now the disposition of these species is crucial: will the F-6-P re-enter the pentose cycle as seems obligatory from the paper by Katz and Wood, or will the triose be subjected in large part to degradation via the Krebs cycle, as indicated for this organism in the foregoing paragraphs? The radiorespirometric patterns in Fig. 2.9 and Table 2.2 provide the following information: (a) gluconate is readily broken down, presumably after initial phosphorylation; (b) the route employed is not the Entner-Doudoroff pathway, either alone or in combination with the pentose cycle. In the Entner-Doudoroff pathway, there should be metabolic equivalence between Col and C-4, C-2 and C-5, or C-3 and C-6. This was not found. Instead, gluconate appears to be metabolized via a sequence (Fig. 2.10):
Mg ~===F-l,6-P GlycolysIs
it
GlycolysIS
- - - - - .... Tnose P iTCA Cycle
C02, etc. Fig. 2.10. Simultaneous operation of glycol)sls and the pentose cycle, and their effect on metaboh~m of admmistered glucose and gluconate. Both circular loops represent pentose cycle oper;tion: the outer loop for the degradation of gluconate and a part 01 glucose, the mner, for the portion of both glucose and gluconate metabolIsm that escapes glycolysis after the first formatIOn of triose phosphate, i e., the portIOn that recycles.
EVALUATION OF METABOLIC PATHWAYS
Gluconate-6-P __
fructose-6-P
maJor
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