Long-chain alcohol production by yeasts.

Fourteen yeast strains from six genera were analysed for the presence of long-chain alcohols, the highest levels being found in Candida albicans. The major alcohols synthesized were saturated, primary alcohols with C14, C16 or C18 chain length with relative proportions of C16 greater than C18 greater than C14. In C. albicans synthesis of long-chain alcohols occurred only after the end of exponential growth. Long-chain alcohol contents were lower in organisms grown aerobically as compared with anaerobically and contents of all three classes increased as the concentration of glucose was raised from 1.0 to 30.0% (w/v). In anaerobic cultures greatest alcohol contents were obtained using medium containing 10% (w/v) glucose. Substituting glucose (10%, w/v) with the same concentration of galactose in aerobic cultures greatly decreased contents of long-chain alcohols, while inclusion of 10% (w/v) glycerol virtually abolished their synthesis. Supplementing anaerobic cultures with odd-chain fatty acids induced synthesis of odd-chain alcohols, Nitrogen limitation induced long-chain alcohol synthesis in aerobically grown Candida maltosa and quantities were increased with conditions of glucose excess and nitrogen limitation.

Effect of glucose and long-chain fatty acids on synthesis of long-chain alcohols by Candida albicans.

Candida albicans, grown aerobically in glucose-containing media, produced C14, C16 and C18 saturated long-chain alcohols only after the end of exponential growth. Contents of C14 alcohols were always lowest, and C16 and C18 alcohol contents about equal. Contents of all three classes of alcohol increased as the concentration of glucose in aerobic cultures harvested after 168 h incubation was raised from 1.0 to 30.0% (w/v). However, in 168 h anaerobic cultures, greatest long-chain alcohol contents in organisms were obtained using media containing 10% (w/v) glucose. Substituting glucose (10%, w/v) with the same concentration of galactose in aerobic cultures greatly decreased contents of long-chain alcohols, while inclusion of 10% (w/v) glycerol virtually abolished their synthesis. Supplementing anaerobic cultures with odd-chain fatty acids induced synthesis of odd-chain alcohols. Maximum conversion of fatty acid to the corresponding long-chain alcohol was observed with heptadecanoic acid. The effect of glucose on production of heptadecanol from exogenously provided heptadecanoic acid was similar to that observed on synthesis of the three major even-chain alcohols in media lacking a fatty-acid supplement. Cell-free extracts of organisms catalysed in vitro conversion of palmitoyl-CoA to 1-hexadecanol.

Production of long-chain alcohols by yeasts.

Fourteen yeast strains from six genera were analysed for the presence of long-chain alcohols. Six strains from three genera contained long-chain alcohols, highest levels being found in Candida albicans. The alcohols were identified and determined by TLC, GLC and GLC-MS. The major long-chain alcohols synthesized by these organisms were saturated, primary alcohols with C14, C16 or C18 chain length. Unsaturated long-chain alcohols were not detected. In all strains that produced long-chain alcohols, the relative proportions were C16 greater than C18 greater than C14. Long-chain alcohol contents were higher in organisms from anaerobically, as compared with aerobically, grown cultures reaching about 650 micrograms (g dry wt organisms)-1 in stationary-phase cultures of C. albicans. In cultures of C. albicans, synthesis of long-chain alcohols occurred only after the end of exponential growth. The alcohols were predominantly present as free alcohols. The fatty-acyl chain-length profile of the triacylglycerol and to a lesser extent the sterol/wax ester fractions from C. albicans reflected that of the long-chain alcohols produced by this yeast.

Experimental reproduction of Potomac horse fever in horses with a newly isolated Ehrlichia organism.

Potomac horse fever, a recently recognized disease of equines, characterized by high fever, leukopenia, and a profuse diarrhea, was studied for its etiology. An Ehrlichia organism was isolated in equine macrophage-fibroblast cell cultures and mouse macrophage cell cultures from the mononuclear cells of blood of infected horses. The agent was continuously propagated in mouse macrophage cell cultures. The organism multiplied in the cytoplasm of mouse macrophage cells and was identified by Giemsa staining, acridine orange staining, and by indirect immunofluorescence with convalescent sera from infected horses. The disease was experimentally reproduced in horses inoculated with Ehrlichia-infected cell culture material. The Ehrlichia organism was reisolated from the blood of these infected horses during the course of the disease. Antibody against the organism was detected in the sera of experimentally infected horses. This study confirmed that the new Ehrlichia organism is the etiological agent of Potomac horse fever.

New findings in methane-utilizing bacteria highlight their importance in the biosphere and their commercial potential.

Recent results, showing that the ubiquitous methane-utilizing bacteria (methanotrophs) can partially oxidize and, in some cases, extensively metabolize complex organic compounds, call for a reappraisal of their role in the cycling of elements in the biosphere. Possible environmental implications and opportunities for industrial exploitation are discussed.

Electrochemical, photoelectrochemical, electrocatalytic and catalytic reduction of redox proteins.

Redox proteins catalyse the reactions of a wide variety of otherwise intractable substrates, such as dinitrogen, alkanes, arenes, terpenes and steroids. Two major factors impede the utilization of these enzymes--the inefficient electron transfer between the enzyme and electrode, and the properties often, but not inevitably, associated with enzymes, such as instability, complexity, and expense. We have now shown that the former can be overcome and that proteins can be coupled, via electrodes, to a number of energy sources; the latter is the subject of much effort elsewhere. We demonstrated previously that certain redox proteins can be reduced very efficiently electrochemically (Fig. 1a). Light and hydrogen are the two other convenient energy sources that could be used for such reductions, and we now report the reduction of cytochrome c by these means.