Identification of saccharolytic enzymes ofZymomonas mobilis CP4

O'Mullan, Patrick; Szakács-Dobozi, M.; Eveleigh, D. E.

doi:10.1007/bf01030465

Cited by 41 publications

(14 citation statements)

References 18 publications

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“…Other compat- Sucrose, however, is a source of fructose through the actions of sucrases (invertases) or levansucrase. Both types of sucrosehydrolyzing activities are present when Z. mobilis grows on sucrose (21,23). (iii) Glucose is the preferred substrate of the glucose facilitator in Z. mobilis, outcompeting fructose (10).…”

Section: Discussionmentioning

confidence: 99%

Sorbitol promotes growth of Zymomonas mobilis in environments with high concentrations of sugar: evidence for a physiological function of glucose-fructose oxidoreductase in osmoprotection

et al. 1994

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The gram-negative ethanologenic bacterium Zymomonas mobilis is able to grow in media containing high concentrations of glucose or other sugars. A novel compatible solute for bacteria, sorbitol, which enhances growth of Z. mobilis at glucose concentrations exceeding 0.83 M (15%), is described. Added sorbitol was accumulated intracellularly up to 1 M to counteract high external glucose concentrations (up to 1.66 M or 30o). Accumulation of sorbitol was triggered by a glucose upshift (e.g., from 0.33 to 1.27 M or 6 to 23%) and was prevented by the uncoupler CCCP (carbonyl cyanide m-chlorophenylhydrazone; 100 tIM). The sorbitol transport system followed Michaelis-Menten kinetics, with an apparent Km of 34 mM and a Vm.. of 11.2 nmol -min-' mg-' (dry mass). Sorbitol was produced by the cells themselves and was accumulated when growing on sucrose (1 M or 36%) by the action of the periplasmic enzyme glucose-fructose oxidoreductase, which converts glucose and fructose to gluconolactone and sorbitol. Thus, Z. mobilis can form and accumulate the compatible solute sorbitol from a natural carbon source, sucrose, in order to overcome osmotic stress in high-sugar media. No other major compatible solute (betaine, proline, glutamate, or trehalose) was detected.The gram-negative, strictly fermentative and ethanologenic bacterium Zymomonas mobilis tolerates high concentrations of both ethanol (up to 13% [24]) and sugar (16,28) in the growth medium. An early report stated that Z. mobilis, (then called Termobacterium mobile), which had been isolated from pulque

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Section: Discussionmentioning

confidence: 99%

Sorbitol promotes growth of Zymomonas mobilis in environments with high concentrations of sugar: evidence for a physiological function of glucose-fructose oxidoreductase in osmoprotection

et al. 1994

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“…Sorbitol is also formed and appears in the medium when cells grow in mixtures composed of glucose and fructose exceeding 5% of sugarcane (Sprenger, 1996). When growing in sucrose medium, Z. mobilis converts the disaccharide into glucose and fructose with the aid of three enzymes: extracellular levansucrase (Lev U), forming glucose and fructose that are converted into levan, a extracellular invertase or sucrase (Inv B) that releases glucose and fructose (Preziosi and Barati, 1990;O'Mullan et al, 1991;Yanase, et al, 1992) and a second invertase (Inv A) whose exact function and location in Z. mobilis are not fully understand. After the fructose release, sorbitol may be produced by the action of the GFOR enzyme, which is an enzyme located at the Z. mobilis periplasmatic region (Aldrich, et al, 1992;Loos et al, 1991;Loos et al, 1993;Loos et al, 1994) and capable of converting the mixtures of glucose and fructose into gluconate-δ-lactone and sorbitol, respectively.…”

Section: Introductionmentioning

confidence: 99%

Influence of high osmotic pressure on sorbitol production by Zymomonas mobilis

Vignoli

Cazetta

Silva

et al. 2010

Braz. arch. biol. technol.

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The objective of the present work was to study the variation on the sorbitol production in relation to the concentration of sugars, (metabolizable or not) and the cultivation time. A full factorial design was used considering the factors such as sucrose and maltose concentration and cultivation time. The addition of sugars caused increases on the sorbitol production up to the concentration of 300g/L however, decreases on the sorbitol production were observed when the concentration reached values above this.Increasing the time of fermentation was statistically significant to sorbitol production, however, little increase the production was noticed after 36h.

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“…However, when grown on media containing sucrose as carbon source, the ethanol yield is considerably reduced because of by-products formation such as levan, fructo-oligosaccharides and sorbitol (Viikari 1988). Recent studies on sucrose metabolism in Z. mobilis indicated the presence of three sucrose hydrolysing enzymes, an intracellular sucrase (SacA), an extracellular sucrase (SacC) and an extracellular levansucrase (sacB) (O'Mullan et al 1990 andPreziosi et al 1990a, b;Yanase et al 1992). The extracellular sucrase and levansucrase activities ofZ.…”

Section: Introductionmentioning

confidence: 99%

The sacB and sacC genes encoding levansucrase and sucrase form a gene cluster in Zymomonas mobilis

et al. 1995

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The Zymomonas mobilis gene sacB that encodes the extracellular levansucrase was cloned and expressed in Escher~chia coli. The gene product exhibited both sucrose hydrolysis activity and levan forming capability. Sub-cellular fractionation ofE. coli carrying pLSS41 revealed that about 95% of the total sucrase activity was detected in the cytoplasmic fraction. The levansucrase gene was overexpressed (about hundred fold) in E. coti under T7 polymerase expression system. Nucleotide sequence analysis of this gene revealed an open reading frame of 1269 bp long coding for a protein of 423 amino acids with a molecular mass of 46.7 KDa. The deduced amino acid sequence was identical to the N-terminal amino acids of protein A51 ofZ. mobilis ZM4. Therefore, the product ofsacB is levansucrase. This is the first extracellular enzyme of Z. mobilis sequenced which does not possess a signal sequence.This gene is located 198 bp upstream ofsacC gene encoding for the extracellular sucrase forming a gene cluster INTRODUCTION

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Identification of saccharolytic enzymes ofZymomonas mobilis CP4

Cited by 41 publications

References 18 publications

Sorbitol promotes growth of Zymomonas mobilis in environments with high concentrations of sugar: evidence for a physiological function of glucose-fructose oxidoreductase in osmoprotection

Sorbitol promotes growth of Zymomonas mobilis in environments with high concentrations of sugar: evidence for a physiological function of glucose-fructose oxidoreductase in osmoprotection

Influence of high osmotic pressure on sorbitol production by Zymomonas mobilis

The sacB and sacC genes encoding levansucrase and sucrase form a gene cluster in Zymomonas mobilis

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