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Abstract

The ability of ruminants to utilize inorganic sulphur was first
indicated by Warth (1932) and has been confirmed by many workers in
recent years (Moir et al., 1967). The reduction of inorganic sulphate
to sulphide has been demonstrated in the rumen (Lewis, 1954; Anderson,
1956) and in vitro (Henderickx, 1961) and inorganic sulphur amino acids
of rumen microbial protein (Block et al., 1951; Henderickx 1961).
Finally cysteine and methionine synthesized in the rumen have been
isolated from tissue proteins of. the host animal (Block and Stekol,
1950; Kulwich et al., 1957).
Although a vast quantity of literature exists concerning the
biology of micro-organisms that oxidize and reduce inorganic sulphur
compounds, until recently little was known about the enzymatic
mechanisms involved in the metabolism of these compounds. A large and
diverse group of micro-organisms reduces sulphate in the small amounts
required for the synthesis of cellular material, as evidenced by the
ability of these organisms to grow on sulphate as their sole source of
sulphur. This small-scale reduction of sulphate has been termed
assimilatory sulphate reduction (Postgate, 1959). A much smaller group
of micro-organisms reduces sulphate in great excess of nutritional
requirements and produces massive amounts of sulphide. This large scale
reduction of sulphate to sulphide has been termed dissimilatory
sulphate reduction (Postgate, 1959).
The chemical reduction of sulphate is a relatively difficult
reaction and little progress was made on the mechanisms of biological
sulphate reduction until Robbins and Lipmann (1958) simultaneously
with Wilson and Bandurski (1958) elucidated the mechanism of sulphate
activation in a number of organisms. Their observations, along with
the initial observations of De Melo and Wizerkanisk (1956) are
summarized in reviews by Gregory and Robbins (1960) and Wilson (1962).
However, little if any published work relates to the mechanisms of
sulphate reduction in the rumen.
This investigation was designed to show that the reduction of
inorganic sulphate in the rumen of sheep followed a similar pathway as
that of Robbins and Lipmann (1958) and Wilson and Bandurski (1958).
The initial stages involved the isolation of the intermediates
adenosine-5'-phosphosulphate (PAPS) and 3'-phospho -adenosine-5'-
phosphosulphate (APS) from the rumen by use of S 35 -labelled sodium
sulphate and the remainder of the experimental work was designed to
show by use of the group V1 anions - molybdate, selenate, chromate and
tungstate - that the enzyme ATP-sulphurylase was involved in the
activation of sulphate by ATP prior to reduction.
The review of literature covers the general sulphur metabolism
and a further section discusses the bacterial sulphate reduction in
more detail.
The experimental section of this thesis is divided into two
parts. In part A, the isolation of APS and PAPS is presented. In
section B the preliminary responses of the group V1 anions on inorganic 4
sulphate reduction are presented followed by a more detailed study of
the responses to these group V1 anions. Finally the behaviour of pure
species Desulphovibris desulphuricans - and sulphate-reducing bacteria
isolated from the rumen in response to group V1 anions has been
investigated.
Raw experimental data and statistical analyses have been
recorded in the appendices.

Item Type:	Thesis - PhD
Authors/Creators:	Bryden, John McGregor
Keywords:	Rumination, Sheep
Copyright Holders:	The Author
Copyright Information:	Copyright 1972 the Author - The University is continuing to endeavour to trace the copyright owner(s) and in the meantime this item has been reproduced here in good faith. We would be pleased to hear from the copyright owner(s).
Additional Information:	Thesis (Ph.D.)--Tasmania, 1973. Bibliography: l. 149-166
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