The Effect of the Chemical Character of Ionic Liquids on Biomass Pre-Treatment and Posterior Enzymatic Hydrolysis.

Ionic liquids have been recognised as interesting solvents applicable in efficient lignocellulosic biomass valorisation, especially in biomass fractionation into individual polymeric components or direct hydrolysis of some biomass fractions. Considering the chemical character of ionic liquids, two different approaches paved the way for the fractionation of biomass. The first strategy integrated a pre-treatment, hydrolysis and conversion of biomass through the employment of hydrogen-bond acidic 1-ethyl-3-methyimidazolim hydrogen sulphate ionic liquid.

Mannitol production by lactic acid bacteria grown in supplemented carob syrup.

Detailed kinetic and physiological characterisation of eight mannitol-producing lactic acid bacteria, Leuconostoc citreum ATCC 49370, L. mesenteroides subsp. cremoris ATCC19254, L.

Hemicelluloses for fuel ethanol: A review.

Hemicelluloses currently represent the largest polysaccharide fraction wasted in most cellulosic ethanol pilot and demonstration plants around the world. The reasons are based on the hemicelluloses heterogeneous polymeric nature and their low fermentability by the most common industrial microbial strains. This paper will review, in a "from field to fuel" approach the various hemicelluloses structures present in lignocellulose, the range of pre-treatment and hydrolysis options including the enzymatic ones, and the role of different microbial strains on process integration aiming to reach a meaningful consolidated bioprocessing.

Wheat straw autohydrolysis: process optimization and products characterization.

Wheat straw was subjected to autohydrolysis treatments in order to selectively hydrolyze the hemicellulose fraction. The effects of temperature (150-240 degrees C) and non-isothermal reaction time on the composition of both liquid and solid phases were evaluated and interpreted using the severity factor (log R0). The operational conditions leading to the maximum recovery of hemicellulose-derived sugars were established for log R0 = 3.

Dilute acid hydrolysis of wheat straw oligosaccharides.

The dilute acid posthydrolysis of wheat straw hemicellulosic oligosaccharides obtained by autohydrolysis was evaluated. An empirical model was used to describe the effect of catalyst concentration (sulfuric acid, 0.1-4% w/w) and reaction time (0-60 min) based on data from a Doehlert experimental design.

Assessment on the fermentability of xylooligosaccharides from rice husks by probiotic bacteria.

Liquors from rice husk autohydrolysis, containing xylooligosaccharides (XOS), other saccharides, and nonsaccharide compounds, were refined by membrane processing to increase the proportion of substituted XOS in refined liquors. XOS were assayed for composition and degree of polymerization (DP) distribution and hydrolyzed with commercial enzymes for obtaining XOS with DP in the range of 2-6. Nanofiltered, hydrolyzed liquors were subjected to ion exchange processing to yield a final product containing monosaccharides, XOS (accounting for 55.

Yeast biomass production in brewery's spent grains hemicellulosic hydrolyzate.

Yeast single-cell protein and yeast extract, in particular, are two products which have many feed, food, pharmaceutical, and biotechnological applications. However, many of these applications are limited by their market price. Specifically, the yeast extract requirements for culture media are one of the major technical hurdles to be overcome for the development of low-cost fermentation routes for several top value chemicals in a biorefinery framework.

Biotechnological valorization potential indicator for lignocellulosic materials.

This report introduces the biotechnological valorization potential indicator (BVPI) concept, a metric to measure the degree of suitability of lignocellulosic materials to be used as feedstock in a biorefinery framework. This indicator groups the impact of the main factors influencing upgrade-ability, both the biological/chemical nature of the materials, and the economical, technological and geographical factors. The BVPI was applied to the identification of the most relevant opportunities and constraints pertaining to the lignocellulosic by-products from the Portuguese agro-industrial cluster.

Evidence for the role of zinc on the performance of dibenzothiophene desulfurization by Gordonia alkanivorans strain 1B.

Gordonia alkanivorans strain 1B is able to desulfurize dibenzothiophene (DBT) to 2-hydroxybiphenyl (2-HBP), the final product of the 4S pathway. However, both the cell growth and the rate of desulfurization can be largely affected by the nutrient composition of the growth medium due to cofactor requirements of many enzymes involved in the biochemical pathways. In this work, the effect of several metal ions on the growth and DBT desulfurization by G.

Dibenzothiophene desulfurization by Gordonia alkanivorans strain 1B using recycled paper sludge hydrolyzate.

Enzymatic hydrolyzates of recycled paper sludge were tested as suitable feedstock for biological desulfurization by Gordonia alkanivorans strain 1B. Only the hydrolyzate obtained after enzymatic mixture dialysis (dialyzed hydrolyzate) allowed dibenzothiophene (DBT) desulfurization, in spite of faster bacterial growth did occur on non-dialyzed hydrolyzate. For dialyzed hydrolyzate, 250microM DBT was consumed after 96h displaying a maximum specific productivity of 2-hydroxybiphenyl of 1.

Xylitol production by Debaryomyces hansenii in brewery spent grain dilute-acid hydrolysate: effect of supplementation.

A brewery spent-grain hemicellulosic hydrolysate was used for xylitol production by Debaryomyces hansenii. Addition of 6 g yeast extract/l increased the xylitol yield to 0.57 g/g, and productivity to 0.

The combined effects of acetic acid, formic acid, and hydroquinone on Debaryomyces hansenii physiology.

The combined effects of inhibitors present in lignocellulosic hydrolysates was studied using a multivariate statistical approach. Acetic acid (0-6 g/L), formic acid (0-4.6 g/L), and hydroquinone (0-3 g/L) were tested as model inhibitors in synthetic media containing a mixture of glucose, xylose, and arabinose simulating concentrated hemicellulosic hydrolysates.

Supplementation requirements of brewery's spent grain hydrolysate for biomass and xylitol production by Debaryomyces hansenii CCMI 941.

The effect of nutrient supplementation of brewery's spent grain (BSG) hydrolysates was evaluated with respect to biomass and xylitol production by Debaryomyces hansenii. For optimal biomass production, supplementation of full-strength BSG hydrolysates required only phosphate (0.5 g l(-1) KH(2)PO(4)), leading to a biomass yield and productivity of 0.

Effects of aliphatic acids, furfural, and phenolic compounds on Debaryomyces hansenii CCMI 941.

Debaryomyces hansenii is a polyol overproducing yeast that can have a potential use for upgrading lignocellulosic hydrolysates. Therefore, the establishment of its tolerance to metabolic inhibitors found in hydrolysates is of major interest. We studied the effects of selected aliphatic acids, phenolic compounds, and furfural.

Kinetic modeling of brewery's spent grain autohydrolysis.

Isothermal autohydrolysis treatments of brewery's spent grain were used as a method for hemicellulose solubilization and xylo-oligosaccharides production. The time course of the concentrations of residual hemicelluloses (made up of xylan and arabinan) and reaction products were determined in experiments carried out at temperatures in the range from 150 to 190 degrees C using liquid-to-solid ratios of 8 and 10 g/g. To model the experimental findings concerning to brewery's spent grain autohydrolysis several kinetic models based on sequential pseudo-homogeneous first-order reactions were tested.

Desulfurization of dibenzothiophene, benzothiophene, and other thiophene analogs by a newly isolated bacterium, Gordonia alkanivorans strain 1B.

A novel bacterium, Gordonia alkanivorans strain 1B, was isolated from hydrocarbon-contaminated soil. Assessment of the biodegradation of distinct organic sulfur-compounds, such as dibenzothiophene (DBT), benzothiophene (BT), DBT sulfone, and alkylated tiophenic compounds, as the sole source of sulfur was investigated. G.

Optimization of Brewery's spent grain dilute-acid hydrolysis for the production of pentose-rich culture media.

Dilute-acid hydrolysis of brewery's spent grain to obtain a pentose-rich fermentable hydrolysate was investigated. The influence of operational conditions on polysaccharide hydrolysis was assessed by the combined severity parameter (CS) in the range of 1.39-3.

Comparison of two posthydrolysis processes of Brewery's spent grain autohydrolysis liquor to produce a pentose-containing culture medium.

A readily fermentable pentose-containing hydrolysate was obtained from Brewery's spent grain by a two-step process consisting of an auto-hydrolysis (converting the hemicelluloses into oligosaccharides) followed by an enzymatic or sulfuric acid-catalyzed posthydrolysis (converting the oligosaccharides into monosaccharides). Enzymatic hydrolyses were performed with several commercial enzymes with xylanolytic and cellulolytic activities. Acid-catalyzed hydrolyses were carried out at 121 degrees C under various sulfuric acid concentrations and reaction times, and the effects of treatments were interpreted by means of a corrected combined severity factor (CS*), which varied in the range of 0.

Production of oligosaccharides by autohydrolysis of brewery's spent grain.

Brewery's spent grain was treated with water in a process oriented towards the production of xylo-oligosaccharides (XOS). A wide range of temperatures and reaction times were tested and the effects of these operational variables on hemicellulose solubilization and reaction products were investigated. The maximal XOS yield (61% of the feedstock xylan) was obtained at 190 degrees C after 5 min of reaction.

Physiological behaviour of Hanseniaspora guilliermondii in aerobic glucose-limited continuous cultures.

The physiology of Hanseniaspora guilliermondii was studied under aerobic glucose-limited conditions using the accelerostat procedure (continuous acceleration of dilution rate) and classical chemostat cultures. By both cultivation techniques this yeast was found to be Crabtree-positive. Up to a dilution rate of 0.

Ca2+ and the bacterial peroxidases: the cytochrome c peroxidase from Pseudomonas stutzeri.

The production of cytochrome c peroxidase (CCP) from Pseudomonas ( Ps.) stutzeri (ATCC 11607) was optimized by adjusting the composition of the growth medium and aeration of the culture. The protein was isolated and characterized biochemically and spectroscopically in the oxidized and mixed valence forms.

Characterisation and application of glycanases secreted by Aspergillus terreus CCMI 498 and Trichoderma viride CCMI 84 for enzymatic deinking of mixed office wastepaper.

Two enzymatic extracts obtained from xylan-grown Aspergillus terreus CCMI 498 and cellulose-grown Trichoderma viride CCMI 84 were characterised for different glycanase activities. Both strains produce extracellular endoxylanase and endoglucanase enzymes. The enzymes optimal activity was found in the temperature range of 45-60 degrees C.

Diversity of microfungi in the phylloplane of plants growing in a Mediterranean ecosystem.

Mediterranean ecosystems have not been investigated as natural habitats for microorganisms in general, and microfungi in particular. Plants harvested in "Serra da Arrábida" (38 degrees 27' N, 9 degrees 02' W), a Mediterranean ecosystem in Portugal, were analyzed for the filamentous microfungi inhabiting their surface. Two field locations with distinct climatic characteristics were studied: 'Fonte do Veado' (38 degrees 28'50" N, 9 degrees 0'17" W; 300 m elevation) located on the northern slope, and 'Mata do Solitário' (38 degrees 27'55" N, 8 degrees 59'35" W; 50 m elevation), on the southern slope.

A physiological and enzymatic study of Debaryomyces hansenii growth on xylose- and oxygen-limited chemostats.

The effect of changing growth rate and oxygen transfer rate (OTR) on Debaryomyces hansenii physiology was studied using xylose-limited and oxygen-limited chemostat cultures, respectively, and complemented with enzymatic assays. Under xylose-limited chemostat (oxygen-excess), neither ethanol nor xylitol was produced over the entire range of dilution rate ( D). The maximal volumetric biomass productivity was 2.

The influence of hexoses addition on the fermentation of d-xylose in Debaryomyces hansenii under continuous cultivation.

The effect of hexoses (glucose and galactose) addition to the feed xylose mineral medium of Debaryomyces hansenii chemostat cultures grown at a constant dilution rate of 0.055 h(-1) was studied. Xylitol was the major product detected amongst all tested conditions.