Degree Type

Dissertation

Date of Award

1985

Degree Name

Doctor of Philosophy

Department

Microbiology

Abstract

A major product of vitamin D(,3) metabolism by either mixed populations of rumen bacteria or by a Clostridium sp. isolated from the rumen is 5(E)-19-nor-10-keto-D(,3) (10-keto-D(,3)). Production of 10-keto-D(,3) depends upon the presence of small amounts of O(,2) and may be related to a mechanism which generates superoxide anions. Supernatant from mixed rumen bacterial incubations catalyzed production of 10-keto-D(,3), but this production was severely reduced when supernatant was passed through a selective membrane (10,000 M.W.) at high pressures (pressure dialysis). Reconstitution of the filtrate (<10,000 M.W.) completely restored activity, suggesting that at least two factors are involved. When saturated levels of vitamin D(,3) were used for the in vitro incubations, several new uncharacterized metabolites of vitamin D(,3), produced by the ruminal isolate of Clostridium sp., were detected. These compounds, unlike 10-keto-D(,3), absorb maximally at 254 nm, indicating that the triene double bond system in the parent molecule is left intact. Steroid transformations by gut bacteria are important reactions because any structural modification can impart altered biological activity, thereby affecting the physiology of the host animal. In the case of the microbial products of vitamin D(,3) metabolism, more work is required to evaluate their biological importance.

DOI

https://doi.org/10.31274/rtd-180813-6153

Publisher

Digital Repository @ Iowa State University, http://lib.dr.iastate.edu/

Copyright Owner

Robert Marshall Gardner

Language

en

Proquest ID

AAI8514401

File Format

application/pdf

File Size

138 pages

Included in

Microbiology Commons

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