sup 31 P nuclear magnetic resonance study of the effect of azide on xylose fermentation by Candida tropicalis

Journal Article · Tue Aug 01 00:00:00 EDT 1989 · Applied and Environmental Microbiology; (USA)

OSTI ID:5133070

Lohmeier-Vogel, E; Vogel, H ^[1]; Skoog, K; Hahn-Haegerdal, B ^[2]

---

1. Univ. of Calgary, Alberta (Canada)
2. Land Univ. (Sweden)

Maximal ethanol production by Candida tropicalis grown on xylose was obtained at an oxygen transfer rate of 5 to 7 mmol/liter per h. Addition of 0.2 mM azide increased the ethanol yield by a factor of 3 to 4, based on the cell mass produced, and decreased the formation of the by-product xylitol by 80%. In the presence of azide, ethanol was reassimilated before the carbon source was depleted. At all oxygenation levels studied, azide caused 25 to 60% of the carbon to be lost, most probable as carbon dioxide. Identical spectra were obtained with {sup 31}P nuclear magnetic resonance spectroscopy performed on extracts of C. tropicalis grown on xylose in the absence and presence of azide. Azide lowered the levels of sugar phosphates. Enzymatic analysis showed extremely low levels of fructose 1,6-diphosphate compared with the levels obtained in the absence of azide, while the level of malate, a citric acid cycle intermediate, was not influenced by azide. {sup 31}P nuclear magnetic resonance spectroscopy performed on xylose-grown whole cells of C. tropicalis showed that azide lowered the intracellular pH, inhibited the uptake of external P{sub i}, and decreased the buildup of polyphosphate in relation to results with untreated cells. Similar results were obtained with the uncoupler of oxidative phosphorylation carbonyl cyanide m-chlorophenylhydrazone (CCCP), except that CCCP treatment led to extremely high levels of internal P{sub i}. The dual effect of azide as a respiratory inhibitor and as an uncoupler is discussed with respect to the metabolism and product formation in xylose-assimilating C. tropicalis.

• OSTI ID: 5133070
• Journal Information: Applied and Environmental Microbiology; (USA), Vol. 55:8; ISSN 0099-2240
• Country of Publication: United States
• Language: English

Related Subjects

09 BIOMASS FUELS
AZIDO COMPOUNDS
BIOLOGICAL EFFECTS
ETHANOL
BIOSYNTHESIS
XYLOSE
FERMENTATION
CANDIDA
METABOLISM
NMR SPECTRA
PHOSPHORUS 31
ALCOHOLS
ALDEHYDES
BIOCONVERSION
CARBOHYDRATES
EUMYCOTA
FUNGI
HYDROXY COMPOUNDS
ISOTOPES
LIGHT NUCLEI
MICROORGANISMS
MONOSACCHARIDES
NUCLEI
ODD-EVEN NUCLEI
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PENTOSES
PHOSPHORUS ISOTOPES
PLANTS
SACCHARIDES
SPECTRA
STABLE ISOTOPES
SYNTHESIS
YEASTS
090900* - Biomass Fuels- Processing- (1990-)