•Phenolic compounds and furan derivatives inhibited the growth of C. tyrobutyricum.•Overexpression of groESL in C. tyrobutyricum enhanced its tolerance to inhibitors.•30 g/L butyrate at a ...productivity of 0.31 g/L·h and yield of 0.37 g/g was obtained.•This provides an effective strategy for enhanced biomass hydrolysates utilization.
Lignocellulosic biomass is the most abundant and renewable substrate for biological fermentation, but the inhibitors present in the lignocellulosic hydrolysates could severely inhibit the cell growth and productivity of industrial strains. This study confirmed that overexpressing of native groESL in Clostridium tyrobutyricum could significantly improve its tolerance to lignocellulosic hydrolysate-derived inhibitors, especially for phenolic compounds. Consequently, ATCC 25755/groESL showed a better performance in butyric acid fermentation with hydrolysates of corn cob, corn straw, rice straw, wheat straw, soybean hull and soybean straw, respectively. When corn straw and rice straw hydrolysates, which showed strong toxicity to C. tyrobutyricum, were used as the substrates, 29.6 g/L and 30.1 g/L butyric acid were obtained in batch fermentation, increased by 26.5% and 19.4% as compared with the wild-type strain, respectively. And more importantly, the butyric acid productivity reached 0.31 g/L·h (vs. 0.20–0.21 g/L·h for the wild-type strain) due to the shortened lag phase.
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Xylitol, a five-carbon polyalcohol, is used in the food and pharmaceutical industries and as a building block in the synthesis of high-value chemicals. It can be sustainably produced ...from renewable sources through xylose assimilating microbe fermentation.
We screened microbial strains for xylitol production and identified Wickerhamomyces anomalus Z1 as a key xylitol producer. Utilizing lignocellulosic biomass hydrolysates for xylitol production poses challenges due to microbial sensitivity to inhibitors from biomass pre-treatment. In this study, an adaptive laboratory evolution (ALE) of W. anomalus Z1 was performed by culturing the yeast in a mineral medium supplemented with gradual increases of sugarcane bagasse hemicellulosic hydrolysate (SCHH) obtained by intensified steam explosion pretreatment. The performance of the adapted yeast, named Wickerhamomyces anomalus ALE, was assessed in comparison to the wild-type strain regarding its capacity to produce xylitol using SCHH. The evolved yeast reached a xylitol yield of 0.11 g xylitol/g xylose whereas the wild-type strain could not produce xylitol. Removing acetic acid from SCHH enhanced W. anomalus ALE performance, with optimal results at 75% hydrolyzed hemicellulose, yielding 0.44 g xylitol/g xylose and 13.41 g/L xylitol.
This study demonstrates the potential of W. anomalus ALE in successfully valorizing the hemicellulosic fraction of sugarcane bagasse for sustainable xylitol production.
How to cite: Bonfiglio F, Cagno M, Nuñez L, et al. Xylitol production by a Wickerhamomyces anomalus strain adapted for enhanced tolerance to sugarcane bagasse hemicellulosic hydrolysate with high content of fermentation inhibitors. Electron J Biotechnol 2024;71. https://doi.org/10.1016/j.ejbt.2024.05.004.
•Recombinant industrial strains of S. cerevisiae for xylose metabolism were cultivated.•Fermentation was on sugars from oat hull and soybean hull hydrolysates.•Evaluation focused on ethanol and ...xylitol production.•Experiments were run in orbital shaker and bioreactors.•Recombinant strains efficiently metabolized all sugars in the hydrolysates.
In this study, we evaluated the capacity of recombinant industrial Saccharomyces cerevisiae YRH 396 and YRH 400 strains to ferment sugars from oat hull and soybean hull hydrolysates into ethanol and xylitol. The strains were genetically modified by chromosomal integration of Pichia stipitis XYLI/XYL2 genes and the overexpression of S. cerevisiae XKS1 genes, in order to have the ability to metabolize xylose, one of the main sugars in lignocellulosic biomass. The strains YRH 396 and YRH 400 were tested by fermenting acid and enzymatic hydrolysates of oat and soybean hull, with different concentrations of sugars, in orbital shaker under conditions of anaerobiosis and oxygen limitation. The YRH 396 strain showed the best kinetic parameters for the production of ethanol and xylitol, thus its metabolism was further studied in bioreactor cultivations. Under anaerobiosis, the maximum consumption of xylose was approximately 35% when using hydrolysates containing similar concentrations of glucose and xylose, whereas when hydrolysates mainly composed of xylose were used, this strain showed a consumption of 73% of the xylose, reaching yields of ethanol of 0.33 g g−1. In bioreactor cultivations under oxygen limitation, xylose consumption reached approximately 65%, and the main product was xylitol, reaching a final concentration of 8.17 g L−1. These results suggest that, in addition to an adaptive evolution process, molecular modifications are necessary for an industrial application of these type of genetically modified strains.
Plants are an attractive sourceof renewable carbon for conversion to biofuels and bio‐based chemicals. Conversion strategies often use a fraction of the biomass, focusing on sugars from cellulose and ...hemicellulose. Strategies that use plant components, such as aromatics and amino acids, may improve the efficiency of biomass conversion. Pseudomonas putida is a promising host for its ability to metabolize a wide variety of organic compounds. P. putida was engineered to produce methyl ketones, which are promising diesel blendstocks and potential platform chemicals, from glucose and lignin‐related aromatics. Unexpectedly, P. putida methyl ketone production using Arabidopsis thaliana hydrolysates was enhanced 2–5‐fold compared with sugar controls derived from engineered plants that overproduce lignin‐related aromatics. This enhancement was more pronounced (~seven‐fold increase) with hydrolysates from nonengineered switchgrass. Proteomic analysis of the methyl ketone‐producing P. putida suggested that plant‐derived amino acids may be the source of this enhancement. Mass spectrometry‐based measurements of plant‐derived amino acids demonstrated a high correlation between methyl ketone production and amino acid concentration in plant hydrolysates. Amendment of glucose‐containing minimal media with a defined mixture of amino acids similar to those found in the hydrolysates studied led to a nine‐fold increase in methyl ketone titer (1.1 g/L).
Plants are an attractive source of renewable carbon for conversion to biofuels and bio‐based chemicals. Conversion strategies often use a fraction of the biomass, focusing on sugars from cellulose and hemicellulose. Strategies that use plant components, such as aromatics and amino acids, may improve the efficiency of biomass conversion. Here we demonstrate that plant‐derived amino acids contribute to substantial increases in the production of methyl ketones, a potential diesel blendstock, by Pseudomonas putida.
A variety of potentially inhibitory degradation products are produced during pretreatment of lignocellulosic biomass. Qualitative and quantitative interrogation of pretreatment hydrolysates is ...paramount to identifying potential correlations between pretreatment chemistries and microbial inhibition in downstream bioconversion processes. In the present study, corn stover, poplar, and pine feedstocks were pretreated under eight different chemical conditions, which are representative of leading pretreatment processes. Pretreatment processes included: 0.7% H₂SO₄, 0.07% H₂SO₄, liquid hot water, neutral buffer solution, aqueous ammonia, lime, lime with oxygen pressurization, and wet oxidation. Forty lignocellulosic degradation products resulting from pretreatment were analyzed using high performance liquid chromatography in combination with UV spectroscopy or tandem mass spectrometry detection (HPLC-PDA-MS/MS) and ion chromatography (IC). Of these compounds, several have been reported to be inhibitory, including furfural, hydroxymethyl furfural, ferulic acid, 3,4-dihydroxybenzaldehyde, syringic acid among others. Formation and accumulation of monitored compounds in hydrolysates is demonstrated to be a function of both the feedstock and pretreatment conditions utilized. Biotechnol. Bioeng. 2010;107: 430-440.
•Sugarcane bagasse hydrolysates was used as a bio resource for lipid production.•Acid, alkaline and ultra-sonication techniques were attempted in pretreatment of Sugarcane bagasse.•16.39 g/l of ...biomass concentration were achieved with Sugarcane bagasse hydrolysates.•In-situ transesterification carried out with the catalyst K2CO3 yields 80% biodiesel.
Depletion of hydrocarbons is forcing to find alternative resources to meet the energy demand of the growing population. Microbial biodiesel as a fuel can act as a cheaper and eco-friendly alternative to fossil fuel. Single-cell oil (SCO) consisting of carbon, hydrogen and oxygen grown over the lignocellulosic biomass using oleaginous microorganisms are triacylglycerols which can be converted to biodiesel, with physicochemical properties similar to conventional diesel. However, several cost-effective pretreatment methods are required to utilize lignocellulosic biomasses. The current research study investigates the SCO yield (and biodiesel characteristics) obtained from sugarcane bagasse hydrolysate through various pretreatment techniques. The pretreatment with 4% v/v H2SO4 at 25 min of ultra-sonication provided the best depolymerisation results (based on the glucose concentration). Yarrowia lipolytica was inoculated into the hydrolysates, allowed to grow at 25 °C, pH of 6.5 and rapid mixing for six days yielded biomass of 16.39 g/l. Biodiesel was extracted from the biomass via in-situ and ex-situ transesterification. In-situ transesterification carried out with the catalyst K2CO3 yields 80% biodiesel. In comparison, 63% were achieved with ex-situ transesterification, where lipid extraction was carried out as a first step and transesterified further in the presence of catalyst KOH to obtain biodiesel. The obtained fatty acid methyl esters (FAME) was subjected to FTIR analysis, and the observed physicochemical properties were within the international standards.
Batch adsorption equilibrium experiments were carried out to find the polymer resin adsorbents suitable for fractionation of constituents in a simulated biomass hydrolysate during sugar purification. ...Considering affinity characteristics of ten neutral and anion exchange polymer resins for its constituents, the polymer resins could be classified as four types of adsorbents. Among type A neutral resin adsorbents, XAD-16 adsorbed the two aromatic aldehydes, furfural and vanillin, most preferentially thanks to π-π interaction between the aromatic compounds and styrene-divinylbenzene matrix of the resin, and strong hydrophobic interaction between aldehyde functionality and the nonpolar matrix. Among type B neutral resin adsorbents, L-493 adsorbed furans and phenolic compounds most preferentially because it had not only styrene-divinylbenzene matrix but also hydrophilic surface interacting with hydroxyl groups of phenolic compounds. IRA67 was the best anion exchange resin adsorbent for selective adsorption of acids because of its weaker π-π interaction than the other anion exchange resins as well as its very high anion exchange ability. A new overall sugar purification process of six adsorption steps was proposed based on these adsorption results, and most components in the simulated biomass hydrolysate could be fractionated with high selectivities in the process.
•Phenolic derivatives from lignin hindered the growth of solventogenic clostridia.•The pathway of the uptake of organic acids was blocked during ABE fermentation.•A mathematic model was established ...to evaluate the magnitude of inhibition.•Biobutanol production was profoundly impeded at a low level of phenolic compounds.•The toxicity was in the order of syringaldehyde > 4-hydroxybenzoic acid > vanillin.
This study aimed to establish a mathematical modeling to evaluate the inhibitory effect of phenolic derivatives on acetone-butanol-ethanol (ABE) fermentation by Clostridium saccharoperbutylacetonicum N1-4. Vanillin, 4-hydroxybenzoic acid, and syringaldehyde were selected to represent guaiacyl, hydroxyphenyl, and syringyl phenols, respectively, to be examined in a series of fed-batch experiments. Results show the presence of phenolic derivatives blocked the pathway of the assimilation of organic acids and reduced cell growth and glucose utilization. The inhibition model projected that the levels of 0.13, 0.14, and 0.04 g L−1 for vanillin, 4-hydroxybenzoic acid, and syringaldehyde, respectively, resulted in 25% inhibition of butanol production, whereas 100% inhibition was predicted at the levels of 4.94, 4.37, and 4.20 g L−1 for vanillin, 4-hydroxybenzoic acid, and syringaldehyde, respectively. Syringaldehyde was more toxic than the other two compounds. The established model described that the phenolic compounds derived from different phenyl propane monomers of lignin severely obstructed biobutanol production.
In recent years, lignocellulosic biomass has become an attractive low-cost raw material for microbial bioprocesses aiming the production of biofuels and other valuable chemicals. However, these ...feedstocks require preliminary pretreatments to increase their utilization by microorganisms, which may lead to the formation of various compounds (acetic acid, formic acid, furfural, 5-hydroxymethylfurfural,
p
-coumaric acid, vanillin, or benzoic acid) with antimicrobial activity. Batch cultures in microplate wells demonstrated the ability of
Yarrowia
strains (three of
Y. lipolytica
and one of
Y. divulgata
) to grow in media containing each one of these compounds. Cellular growth of
Yarrowia lipolytica
W29 and NCYC 2904 (chosen strains) was proven in Erlenmeyer flasks and bioreactor experiments where an accumulation of intracellular lipids was also observed in culture medium mimicking lignocellulosic biomass hydrolysate containing glucose, xylose, acetic acid, formic acid, furfural, and 5-HMF. Lipid contents of 35% (w/w) and 42% (w/w) were obtained in bioreactor batch cultures with
Y. lipolytica
W29 and NCYC 2904, respectively, showing the potential of this oleaginous yeast to use lignocellulosic biomass hydrolysates as feedstock for obtaining valuable compounds, such as microbial lipids that have many industrial applications.
Key Points
•
Yarrowia strains tolerate compounds found in lignocellulosic biomass hydrolysate
•
Y. lipolytica consumed compounds found in lignocellulosic biomass hydrolysate
•
42% (w/w) of microbial lipids was attained in bioreactor batch cultures
Graphical Abstract
Seaweed biomass in Korea is rich in galactose following hydrolysis, and leveraging this resource for enhancing the biohydrogen production is the aim of this study. The study investigates the ...biohydrogen production potential of a newly isolated pure strain,
Clostridium
sp. JH03, utilizing galactose and seaweed biomass as renewable feedstocks. The strain could utilize galactose as the sole carbon source for biohydrogen production, with a maximum hydrogen yield of 1.61 mol H
2
/mol galactose. The parameters included pH, temperature, and initial galactose concentration, which were varied to determine the optimal conditions for maximum biohydrogen production. The optimal conditions for biohydrogen production were pH 9 and a temperature of 25 °C, with an initial galactose concentration of 10 g/L. Moreover, hydrogen production from seaweed hydrolysate by
Clostridium
sp. JH03 resulted in maximum production of 1.71 mol H
2
/mol galactose. The study also investigated that combining sludge, a common practice in dark fermentation, with JH03 increased biohydrogen production by up to 34%. By addressing the need for clean energy and reducing raw materials price using biomass, this study contributes to the advancement of sustainable and cost-compatible energy solutions.
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