SummaryA small Gram-negative coccus, which brings about the reductive fission of the hepatotoxic pyrrolizidine alkaloids, has been isolated from the rumen contents of Australian Merino sheep. The organism was cultured in a partially defined medium, without rumen fluid, but containing yeast extract. Strictly anaerobic conditions and the presence of carbon dioxide were essential for growth. With limiting quantities of yeast extract, growth was greatly stimulated by any of several carbohydrates or moderately stimulated by the alkaloid heliotrine plus hydrogen. The products of the reductive cleavage of heliotrine were heliotric acid and 7()(-hydroxy-l-methylene-8()(-pyrrolizidine. One mole of hydrogen reduced one mole of heliotrine to produce one mole each of the two products, accounting completely for the substrate consumed. Formate in stoichiometric quantities could replace molecular hydrogen as hydrogen donor in the reaction in which heliotrine acted as hydrogen acceptor. With [UCJformate as hydrogen donor 14CO. was evolved in stoichiometric amounts. The additional growth brought about by the degradation of heliotrine was proportional to the amount of heliotrine degraded, the organism appearing to derive energy from the reaction. Under strictly anaerobic conditions neither growth of the organism nor degradation of heliotrine was dependent on or stimulated by the presence of vitamin B12 in the medium. A method is described for the estimation of heliotrine.
Aims: This study sought to develop a less expensive medium for growth of the polyhydroxyalkanoate‐producing bacterium Rhodospirillum rubrum from the ethanol production coproduct, condensed corn solubles (CCS). Methods and Results: Small‐scale trials using R. rubrum were performed in aerated or anaerobic stoppered serum bottles filled with media. The CCS (240 g l−1) achieved a maximum cell density and growth rate comparable with the defined supplemented malate‐ammonium medium (mSMN) or tryptic soy broth. Microaerophilic solubles medium cultures exhibited significantly higher maximum cell densities and growth rates than did strictly anaerobic cultures; while illumination, nickel or biotin addition had no effect. Growth of R. rubrum in a pH controlled bioreactor was significantly better in CCS (240 g l−1) than in mSMN medium and supported production of 0·36% (cell dry weight) poly‐(3‐hydroxybutyrate‐Co‐3‐hydroxyvalerate) after 24 h. Conclusions: A CCS medium was devised that supported R. rubrum growth for biopolymer production as effective as the defined medium. Significance and Impact of the Study: This study demonstrates that a more economical medium can be developed for biopolymer production using a low value coproduct from ethanol production. The impact is that this inexpensive solubles medium may make it more economical to produce the biopolymer on a commercial scale.
Approximately 70% of the fatty acids present in plant lipids are unsaturated; the major component is cis-9,cis-12,cis-15-octadecatrienoic acid (Garton 1963). After ingestion by ruminants, these acids are readily hydrogenated by microorganisms in the rumen to form a complex mixture of positional and geometrical C18 isomers (Shorland et al. 1957;Ward, Scott, and Dawson 1964;Wilde and Dawson 1966;Kemp and Dawson 1968). Kemp and Dawson (1968) showed that the first stage in the hydrogenation of linolenic acid by a mixed population of washed rumen microorganisms was an isomerization to form a conjugated triene, cis-9,trans-ll,cis-15-octadecatrienoic acid. This acid was identified by Kepler and Tove (1967) after pure cultures of Bmyrivibrio fibrisolvens were incubated with linolenic acid. These authors also showed that this conjugated triene was hydrogenated to a non-conjugated diene, which from its retention time on gas-liquid chromatography had at least one trans double bond. However, in these experiments, no further hydrogenation of the diene was detected. Wilde and Dawson (1966) incubated linolenic acid with pure cultures of several bacteria found in the rumen and only B. fibrisolvens and Escherichia coli possessed any hydrogenating activity and the intermediary products were not studied in detail. Recently, Kemp and White (1968) briefly reported the isolation from the rumen of three species of anaerobic bacteria which could hydrogenate linolenic and linoleic acids to monoenoic acids. The present studies were undertaken to extend our knowledge of the process of hydrogenation and to identify the products formed during the metabolism of linolenic and linoleic acids by pure cultures of a rumen micrococcus. A preliminary report of this work has already been published (Mills et al. 1969). Experimental (a) I80lation and Incubation of the Micrococcus with [14C]Fatty Acid8Cultures of the rumen miorooooous were isolated from rumen oontents by prooedures outlined previously (Russell and Smith 1968). The organism was inoubated for 24 hr at 38°C under anaerobio oonditions, in oarbon dioxide, in a medium desoribed by Russell and Smith (1968) oontaining [14C]fatty aoid (5 p.Ci, 0·1 p.mole) oomplexed to bovine serum albumin (Kessler, Demeny, and Sobotka 1967, method B). Vessels oontaining boiled suspensions of the miorooocous were prepared as controls for each acid.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.