Influence of inhibitory compounds and minor sugars on xylitol production by Debaryomyces hansenii

Abstract

To obtain in-depth information on the overall metabolic behavior of the new good xylitol producer Debaryomyces hansenii UFV-170, batch bioconversions were carried out using semisynthetic media with compositions simulating those of typical acidic hemicellulose hydrolysates of sugarcane bagasse. For this purpose, we used media containing glucose (4.3-6.5 g/L), xylose (60.1-92.1 g/L), or arabinose (5.9-9.2 g/L), or binary or ternary mixtures of them in either the presence or absence of typical inhibitors of acidic hydrolysates, such as furfural (1.0-5.0 g/L), hydroxymethylfurfural (0.01- 0.30 g/L), acetic acid (0.5-3.0 g/L), and vanillin (0.5-3.0 g/L). D. hansenii exhibited a good tolerance to high sugar concentrations as well as to the presence of inhibiting compounds in the fermentation media. It was able to produce xylitol only from xylose, arabitol from arabinose, and no glucitol from glucose. Arabinose metabolization was incomplete, while ethanol was mainly produced from glucose and, to a lesser less extent, from xylose and arabinose. The results suggest potential application of this strain in xyloseto- xylitol bioconversion from complex xylose media from lignocellulosic materials.

Xylose reductase activity in Debaryomyces hansenii UFV-170 cultivated in semi-synthetic medium and cotton husk hemicellulose hydrolyzate

“…After 20-24 h of incubation, cells were collected by centrifugation at 4°C (4,0009g for 5 min) and washed twice with 5-ml sterile water. Cells were cultivated for 24 h in 125-ml Erlenmeyer flasks containing 25 ml of the same medium used for pre-cultivations under the optimum growth conditions determined in previous work (30°C and 200 rpm) [11], and then collected either after 10-12 or 20-24 h to get samples representative of the log and the stationary phases, respectively [13]. The starting inoculum concentration was 0.05-0.06 g l -1 cell DW.…”

“…Nevertheless, the conversion process using microorganisms can lead to unsatisfactory productions of xylitol due to the influence of some culture conditions. Therefore, an alternative enzymatic approach, employing NAD(P)H-dependent XR [9,10] from new good xylitol producers like the new isolate Debaryomyces hansenii UFV-170 [11][12][13], would be hoped to reduce the production costs of xylitol and ethanol from plant biomass [14].…”

“…The present work reports a preliminary attempt to better understand the XR regulation in D. hansenii, a good xylitol producer [11]. For this purpose, we have screened for the activity of this enzyme in extracts of D. hansenii UFV-170, which had been previously grown either in semi-synthetic media containing different sugars, including pentoses, hexoses, disaccharides and a pentitol, or in hemicellulose hydrolyzate of cotton husk.…”

Microbial Production of Xylitol from Oil Palm Empty Fruit Bunches Hydrolysate: The Effect of Glucose Concentration

“…Another xylitol advantage is its anti-cariogenic property. This property, along with xylitol's ability to pertain mixture moisture explains why xylitol has an important role as a toothpaste constituent 3) .…”

Effect of Furfural, Vanillin and Syringaldehyde on Candida guilliermondii Growth and Xylitol Biosynthesis

“…Lignin and xylose-derived degradation products are commonly found at inhibitory levels in concentrated hemicellulose hydrolysates from sugarcane bagasse [23,[16][17], although the concentrations of specific chemical species may vary widely depending on the feedstock and pretreatment conditions. The objectives of this research were to experimentally examine the effects of the inhibitors furfural, syringaldehyde, and vanillin on C. guilliermondii growth (low cell density) and xylitol production (high cell density) using semi-synthetic medium in microtiter plates and bench-scale fermentors, respectively.…”