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To increase the limited commercial utility and lessen the negative environmental effects of the massive growth of brown macroalgae, this work illustrates the feasibility of valorizing the invasively proliferated Sargassum latifolium into different value‐added products. The proximate analysis recommends its applicability as a solid biofuel with a sufficient calorific value (14.82 ± 0.5 MJ/kg). It contains 6.00 ± 0.07% N + P2O5 + K2O and 29.61 ± 0.05% organic C. Its nutritional analysis proved notable carbohydrate, ash, protein, and fiber contents with a rational amount of lipid and a considerable amount of beneficial macronutrients and micronutrients, with a low concentration of undesirable heavy metals. That recommends its application in the organic fertilizer, food, medicine, and animal fodder industries. A proposed eco‐friendly sequential integrated process valorized its biomass into 77.6 ± 0.5 mg/g chlorophyll, 180 ± 0.5 mg/g carotenoids, 5.86 ± 0.5 mg/g fucoxanthin, 0.93 ± 0.5 mg/g β‐carotene, 21.97 ± 0.5% (w/w) alginate, and 16.40 ± 0.5% (w/w) cellulose, with different industrial and bioprocess applications. Furthermore, Aspergillus galapagensis SBWF1, Mucor hiemalis SBWF2, and Penicillium oxalicum SBWF3 (GenBank accession numbers OR636487, OR636488, and OR636489) have been isolated from its fresh biomass. Those showed wide versatility for hydrolyzing and saccharifying its polysaccharides. A Gram‐negative Stutzerimonas stutzeri SBB1(GenBank accession number OR764547) has also been isolated with good capabilities to ferment the produced pentoses, hexoses, and mannitol from the fungal saccharification, yielding 0.25 ± 0.014, 0.26 ± 0.018, and 0.37 ± 0.020 g ethanol/g algal biomass, respectively. Furthermore, in a pioneering step for valuing the suggested sequential biomass hydrolysis and bioethanol fermentation processes, the spent waste S. latifolium disposed of from the saccharification process has been valorized into C‐dots with potent biocidal activity against pathogenic microorganisms. [ABSTRACT FROM AUTHOR]

Summary: This study investigated the effects of reducing sugars and protein‐to‐sugar ratios on generating volatile compounds from nutritional yeast hydrolysates after Maillard reaction. Nutritional yeast extract (NYE) was cleaved using Flavourzyme® at an enzyme‐to‐substrate ratio of 0.5% w/w, followed by heat treatment with varying concentrations of reducing sugars (i.e., hexoses: glucose and fructose and pentoses: xylose and ribose). The results showed that pentoses generate higher numbers and concentrations of volatiles than hexoses, especially furans, Strecker aldehydes, and sulphur‐containing compounds such as dimethyl disulphide. However, hexoses produced higher concentrations of pyrazines. Strecker aldehydes and pyrazines served as key aroma‐active compounds in meat aroma. Likewise, sulphur‐containing compounds played an important role in meat aroma due to their low detection threshold. The results showed that reducing sugars significantly impacts the volatile profile of NYE, potentially influencing the formation of meaty aroma compounds. These findings demonstrate the potential of MRPs to enhance meaty flavours due to the presence of volatile compounds with characteristics of cooked meat. [ABSTRACT FROM AUTHOR]

Plant-based waste biomass with lignocellulose as an important component is produced in large quantities worldwide every year. The components of lignocellulose that typically exhibit high utilization value include cellulose and hemicellulose, as well as pentoses and hexoses derived from their hydrolysis. As a pretreatment for the hydrolysis process, delignification is a pivotal step to enhance cellulose/hemicellulose accessibility and achieve high yields of fermentable sugars. Additionally, deep eutectic solvents (DESs) are the most widely used solvents for delignification during biomass fractionation due to their clean and environmentally friendly attributes. DESs dissolve lignin by inducing a large amount of β-O-4 bond cleavage and partial carbon–carbon bond cleavage, retaining cellulose in the solid residue, while most of the hemicellulose is hydrolyzed in DES pretreatment. This article provides a comprehensive review of the influence of DESs in the lignocellulose separation process. Key factors such as lignin removal rate, sugar conversion rate, and product chemical structure are critically reviewed to assess the feasibility of employing DESs for lignocellulose separation. [ABSTRACT FROM AUTHOR]

Pseudomonas putida have emerged as promising biocatalysts for the conversion of sugars and aromatic compounds obtained from lignocellulosic biomass. Understanding the role of carbon catabolite repression (CCR) in these strains is critical to optimize biomass conversion to fuels and chemicals. The CCR functioning in P. putida M2, a strain capable of consuming both hexose and pentose sugars as well as aromatic compounds, was investigated by cultivation experiments, proteomics, and CRISPRi-based gene repression. Strain M2 co-utilized sugars and aromatic compounds simultaneously; however, during cultivation with glucose and aromatic compounds (p-coumarate and ferulate) mixture, intermediates (4-hydroxybenzoate and vanillate) accumulated, and substrate consumption was incomplete. In contrast, xylose-aromatic consumption resulted in transient intermediate accumulation and complete aromatic consumption, while xylose was incompletely consumed. Proteomics analysis revealed that glucose exerted stronger repression than xylose on the aromatic catabolic proteins. Key glucose (Eda) and xylose (XylX) catabolic proteins were also identified at lower abundance during cultivation with aromatic compounds implying simultaneous catabolite repression by sugars and aromatic compounds. Reduction of crc expression via CRISPRi led to faster growth and glucose and p-coumarate uptake in the CRISPRi strains compared to the control, while no difference was observed on xylose+p-coumarate. The increased abundances of Eda and amino acid biosynthesis proteins in the CRISPRi strain further supported these observations. Lastly, small RNAs (sRNAs) sequencing results showed that CrcY and CrcZ homologues levels in M2, previously identified in P. putida strains, were lower under strong CCR (glucose+p-coumarate) condition compared to when repression was absent (p-coumarate or glucose only).IMPORTANCEA newly isolated Pseudomonas putida strain, P. putida M2, can utilize both hexose and pentose sugars as well as aromatic compounds making it a promising host for the valorization of lignocellulosic biomass. Pseudomonads have developed a regulatory strategy, carbon catabolite repression, to control the assimilation of carbon sources in the environment. Carbon catabolite repression may impede the simultaneous and complete metabolism of sugars and aromatic compounds present in lignocellulosic biomass and hinder the development of an efficient industrial biocatalyst. This study provides insight into the cellular physiology and proteome during mixed-substrate utilization in P. putida M2. The phenotypic and proteomics results demonstrated simultaneous catabolite repression in the sugar-aromatic mixtures, while the CRISPRi and sRNA sequencing demonstrated the potential role of the crc gene and small RNAs in carbon catabolite repression.

The Pseudomonas putida group in the Gammaproteobacteria has been intensively studied for bioremediation and plant growth promotion. Members of this group have recently emerged as promising hosts to convert intermediates derived from plant biomass to biofuels and biochemicals. However, most strains of P. putida cannot metabolize pentose sugars derived from hemicellulose. Here, we describe three isolates that provide a broader view of the pentose sugar catabolism in the P. putida group. One of these isolates clusters with the well-characterized P. alloputida KT2440 (Strain BP6); the second isolate clustered with plant growth-promoting strain P. putida W619 (Strain M2), while the third isolate represents a new species in the group (Strain BP8). Each of these isolates possessed homologous genes for oxidative xylose catabolism (xylDXA) and a potential xylonate transporter. Strain M2 grew on arabinose and had genes for oxidative arabinose catabolism (araDXA). A CRISPR interference (CRISPRi) system was developed for strain M2 and identified conditionally essential genes for xylose growth. A glucose dehydrogenase was found to be responsible for initial oxidation of xylose and arabinose in strain M2. These isolates have illuminated inherent diversity in pentose catabolism in the P. putida group and may provide alternative hosts for biomass conversion.

This study investigated the changes in colour, amino acids, and volatile flavour compounds in the enzymatic hydrolysates of chicken carcasses containing different types and amounts of reducing sugars (xylose, arabinose, glucose, and fructose), so as to develop a chicken-based flavouring agent. Before heat treatment at 100 °C for 60 min, the chosen reducing sugars were separately added to the chicken carcass hydrolysate at its natural pH. Pentoses decreased pH more significantly than hexoses in the chicken carcass hydrolysate. The browning degree followed the pattern of pH decline, as pentoses caused more intense browning than hexoses, with xylose dosage having the greatest effect on the colour changes (ΔE). Fructose addition notably reduced free amino acids (FAAs) and cystine contents. Furthermore, phenylalanine decreased with increasing dosages of arabinose, xylose, and fructose. Glutamic acid content decreased significantly with fructose addition but showed insignificant changes with xylose. At the same dosage, the addition of pentoses resulted in the production of more sulphur-containing volatile compounds like methional, 2-[(methylthio) methyl] furan, and dimethyl disulphide than hexoses. Methional and furfural, which provide a roasted, savoury flavour, were produced by adding more xylose. Heat treatment with xylose also removed hexanal, the main off-odourant. [ABSTRACT FROM AUTHOR]

In plants, heteromorphic self-incompatibility (HetSI) is a strategy for avoiding self-pollination and promoting outcrossing, and during this process, numerous protein-protein interaction events occur between the pistil and pollen. Previous studies in Primula and Fagopyrum that focused on HetSI systems have provided interesting insights; however, the molecular mechanism underlying HetSI remains largely unknown. In this study, we profiled the proteome of Plumbago auriculata stigmas before and after self-incompatible (SI) and self-compatible (SC) pollination. Comparative analyses were conducted by 4D-DIA (Four-dimensional data independent acquisition), a promising technology that increases the sensitivity and reduces the spectral complexity of proteomic analysis by adding a fourth dimension, ion mobility. The results revealed 33387 peptides and 5311 proteins in all samples. The pathways in which the differentially expressed proteins (DEPs) identified in the P × P (Pin style self-pollinated with pin pollen) vs. PS (Pin style) and T × T (Thrum style self-pollinated with thrum pollen) vs. TS (Thrum style) comparisons were significantly enriched were biosynthesis of secondary metabolites and pentose and glucuronate interconversions. In the P × T (Pin style cross-pollinated with thrum pollen) vs. PS and T × P (Thrum style cross-pollinated with pin pollen) vs. TS comparison, the top three pathways were biosynthesis of secondary metabolites, pentose and glucuronate interconversions, and phenylpropanoid biosynthesis. The phenylpropanoid biosynthesis, cutin, suberine and wax biosynthesis, and flavonoid biosynthesis pathways were enriched in the P × T vs. P × P comparison, and starch and sucrose metabolism, glycerophospholipid metabolism, and alpha-linolenic acid metabolism were abundant in the T × T vs. T × P comparison. The enriched pathways between PS and TS were the biosynthesis of secondary metabolites, phenylpropanoid biosynthesis, and pentose and glucuronate interconversion. Self-incompatibility protein S1 (SI S1), Mitogen-activated protein kinase 3/4 (MPK3/4), Mitogen-activated protein kinase kinase 2/3 (M2K2/3), Exocyst complex component EXO70A1 (E70A1) and Thioredoxin H1/2 (TRXH1/2) were found to be HetSI-related candidates, and O-fucosyltransferase 23 (OFT23), 3- ketoacyl-CoA synthase 6 (KCS6), Receptor-like protein kinase FERONIA (FERON), Fimbrin-5 (FIMB5), Pollen-specific leucine-rich repeat extensin-like protein 4 (PLRX4), Transcription initiation factor IIB-2 (TF2B2) and Pectinesterase 1 (AL11A), etc., were identified as other regulatory transducers. These findings combined with our morphological and reactive oxygen species (ROS) intensity analyses indicate that P. auriculata has typical dry-stigmas and that the HetSI mechanism might differ between the pin and thrum. SI S1 might be the key factor in HetSI, and ROS are overexpressed during SC pollination to rapidly activate the mitogen-activated protein kinase (MAPK)-mediated phosphorylation of E70A1 to maintain stigma receptivity in plants with HetSI. [ABSTRACT FROM AUTHOR]

Providing simultaneously autotrophic and heterotrophic carbon sources is a promising strategy to overcome the limits of autotrophic syngas fermentations. D-xylose and L-arabinose are particularly interesting as they can be obtained by the hydrolysis of lignocellulosic biomass. The individual conversion of varying initial concentrations of these pentoses and D-fructose as reference was studied with C. autoethanogenum in fully controlled stirred-tank reactors with a continuous syngas supply. All mixotrophic batch processes showed increased biomass and product formation compared to an autotrophic reference process. Simultaneous CO and D-xylose or L-arabinose conversion was observed in contrast to D-fructose. In the mixotrophic batch processes with L-arabinose or D-xylose, the simultaneous CO and sugar conversion resulted in high final alcohol-to-acid ratios of up to 58 g g−1. L-arabinose was superior as a mixotrophic carbon source because biomass and alcohol concentrations (ethanol and 2,3-butanediol) were highest, and significant amounts of meso-2,3-butanediol (>1 g L−1) in addition to D-2,3-butanediol (>2 g L−1) were solely produced with L-arabinose. Furthermore, C. autoethanogenum could not produce meso-2,3 butanediol under purely heterotrophic conditions. The mixotrophic production of meso-2,3-butanediol from L-arabinose and syngas, both available from residual lignocellulosic biomass, is very promising for use as a monomer for bio-based polyurethanes or as an antiseptic agent. [ABSTRACT FROM AUTHOR]

Hydrogen produced from lignocellulosic biomass via dark fermentation is a promising alternative to fossil fuels. This study assessed fermentative H 2 production from single sugars and sugar mixtures mimicking real lignocellulose hydrolysates during a continuous process. The highest hydrogen production rate (HPR) was obtained with pentose sugars, reaching 8.80 and 8.09 L/L-d for arabinose and xylose, respectively. Glucose showed the lowest HPR (6.19 L/L-d), while in the case of sugar mixtures (glucose, cellobiose, xylose, arabinose), HPR was approximately 7.3 L/L-d and was lower than expected from calculations. Thus, cofermentation reduced the H 2 production potential. It was shown that pentose sugars are preferred for hydrogen production, but their utilization is limited by the presence of glucose, which is utilized preferentially in sugar mixtures. Xylose, arabinose and sugar mixtures showed similar H 2 yields (approximately 0.29 mol H 2 /mol C), so the efficiency of substrate conversion into H 2 was comparable for these substrates. The microbial community distribution showed that the Clostridium genus was dominant regardless of the substrate, with Clostridium beijerinckii and Clostridium guangxiense being the main bacterial species. Different substrates did not significantly affect the type of microorganisms present in the microbiome and changed only their relative abundance. [Display omitted] • Long-term continuous fermentative H 2 production from single sugars and their mixtures. • The highest HPR obtained for arabinose (8.80 L/L-d) with 96% substrate utilization. • Sugar mixtures exhibited lower HPRs due to the low consumption of arabinose. • Pentoses are preferred for H 2 production, but their utilization is limited by glucose. • The lowest substrate consumption for glucose resulted in the lowest HPR. [ABSTRACT FROM AUTHOR]

Vinyl‐substituted carbohydrates have been synthesized from glycals derived from hexoses and pentoses. Key step is the radical reaction of xanthates in the presence of triethylborane, a non‐toxic reagent. The mechanism has been investigated by isolation of various side products, which speak for a reversibility of the cyclopropylmethyl radical ring‐opening. Compared to reactions with tributyltin hydride, higher regioselectivities in favor of the 2‐vinyl‐substituted sugars have been obtained. Yields are slightly lower with triethylborane, but all products have been isolated in analytically pure form. The new reaction is applicable to benzyl‐ and silyl‐protected carbohydrates, which makes free sugars accessible as well. Overall, more than 15 1,2‐dideoxy‐2‐vinyl carbohydrates have been synthesized from simple precursors in only few steps. [ABSTRACT FROM AUTHOR]

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Next to d-glucose, the pentoses l-arabinose and d-xylose are the main monosaccharide components of plant cell wall polysaccharides and are therefore of major importance in biotechnological applications that use plant biomass as a substrate. Pentose catabolism is one of the best-studied pathways of primary metabolism of Aspergillus niger, and an initial outline of this pathway with individual enzymes covering each step of the pathway has been previously established. However, although growth on l-arabinose and/or d-xylose of most pentose catabolic pathway (PCP) single deletion mutants of A. niger has been shown to be negatively affected, it was not abolished, suggesting the involvement of additional enzymes. Detailed analysis of the single deletion mutants of the known A. niger PCP genes led to the identification of additional genes involved in the pathway. These results reveal a high level of complexity and redundancy in this pathway, emphasizing the need for a comprehensive understanding of metabolic pathways before entering metabolic engineering of such pathways for the generation of more efficient fungal cell factories.

The nosocomial pathogen Acinetobacter baumannii is well known for its extraordinary metabolic diversity. Recently, we demonstrated growth on L‐arabinose, but the pathway remained elusive. Transcriptome analyses revealed two upregulated gene clusters that code for isoenzymes catalysing oxidation of a pentonate to α‐ketoglutarate. Molecular, genetic, and biochemical experiments revealed one branch to be specific for L‐arabonate oxidation, and the other for D‐xylonate and D‐ribonate. Both clusters also encode an uptake system and a regulator that acts as activator (L‐arabonate) or repressor (D‐xylonate and D‐ribonate). Genes encoding the initial oxidation of pentose to pentonate were not part of the clusters, but our data are consistent with the hypothesis of a promiscous, pyrroloquinoline quinone (PQQ)‐dependent, periplasmic pentose dehydrogenase, followed by the uptake of the pentonates and their degradation by specific pathways. However, there is a cross‐talk between the two different pathways since the isoenzymes can replace each other. Growth on pentoses was found only in pathogenic Acinetobacter species but not in non‐pathogenic such as Acinetobacter baylyi. However, mutants impaired in growth on pentoses were not affected in traits important for infection, but growth on L‐arabinose was beneficial for long‐term survival and desiccation resistance in A. baumannii ATCC 19606. [ABSTRACT FROM AUTHOR]

The use of all sugars from biomass fractionation – that is, hexoses and pentoses – is essential to develop feasible processes in a biorefinery context. Hexoses are converted into different products by most microorganisms. The main issue is the conversion of pentoses, especially when mixed with hexoses. Improving sugar conversion in co‐fermentation is a major challenge, which was explored in this work. Co‐culture using Saccharomyces cerevisiae and evolved Kluyveromyces marxianus strains was evaluated by screening using 24 deep‐well plates. Glucose depletion and 83% of xylose conversion were achieved with supplemented hemicellulosic hydrolysate medium (medium volume corresponding to 2/5 of deep‐well volume), and initial cell concentrations of 2.5 g L‐1 for each yeast, incubated at 150 rpm. The screening strategy provided reliable data that confirmed the co‐culture as a promising approach for the co‐assimilation of biomass‐derived sugars. The importance of aeration control for effective xylose assimilation was also pointed out. [ABSTRACT FROM AUTHOR]

Sustainably produced renewable biomass has the potential to replace fossil-based feedstocks, for generation of biobased fuels and chemicals of industrial interest, in biorefineries. In this context, seaweeds contain a large fraction of carbohydrates that are a promising source for enzymatic and/or microbial biorefinery conversions. The thermoanaerobe Thermoanaerobacterium AK17 is a versatile fermentative bacterium producing ethanol, acetate and lactate from various sugars. In this study, strain AK17 was engineered for more efficient production of ethanol by knocking out the lactate and acetate side-product pathways. This was successfully achieved, but the strain reverted to acetate production by recruiting enzymes from the butyrate pathway. Subsequently this pathway was knocked out and the resultant strain AK17_M6 could produce ethanol close to the maximum theoretical yield (90%), leading to a 1.5-fold increase in production compared to the wild-type strain. Strain AK17 was also shown to successfully ferment brown seaweed hydrolysate from Laminaria digitata to ethanol in a comparatively high yield of 0.45 g/g substrate, with the primary carbon sources for the fermentations being mannitol, laminarin-derived glucose and short laminari-oligosaccharides. As strain AK17 was successfully engineered and has a wide carbohydrate utilization range that includes mannitol from brown seaweed, as well as hexoses and pentoses found in both seaweeds and lignocellulose, the new strain AK17_M6 obtained in this study is an interesting candidate for production of ethanol from both second and third generations biomass. [ABSTRACT FROM AUTHOR]

The hydrogen-producing bacteria SP4 and SP6 were isolated from the compost and identified by 16S rRNA gene sequencing as Clostridium butyricum and Clostridium beijerinckii , respectively. A comparative study on the biohydrogen-producing activity of the isolated strains was carried out using mono-, di- and tri-saccharides belonging to both hexoses (maltose, glucose, mannose, fructose, lactose, galactose, sucrose, raffinose, cellobiose) and pentoses (xylose). To assess the biotechnological significance, real wastewater rich in sugars (cheese whey, confectionery wastewater, sugar beet processing wastewater) was also used as a substrate. C. butyricum SP4 fermented sugars with a yield of 0.93–1.52 mol H 2 /mol hexose (pentose); the maximum yield was obtained from fructose, the minimum – from raffinose and cellobiose. The most preferred substrate for C. beijerinckii SP6 was sucrose with a yield of 1.76 mol H 2 /mol hexose, while cellobiose yielded only 0.64 mol H 2 /mol hexose. Overall, the efficiency of converting wastewater to H 2 by C. butyricum SP4 was also slightly lower (66–93 ml H 2 /g chemical oxygen demand (COD)) than that of C. beijerinckii SP6 (76–103 ml H 2 /g COD). Even though the main soluble metabolite products (SMPs) for both isolates were acetate and butyrate, C. butyricum SP4 also produced a significant amount of ethanol (up to 21.5% of SMPs) and formate (up to 32.5% of SMPs), and C. beijerinckii SP6 – lactate (up to 25% of SMPs). A distinctive feature of C. beijerinckii SP6 was a significantly lower (almost 2 times) yield of SMPs, while C. butyricum SP4 had a higher rate of H 2 production according to the results obtained from the kinetic study using the modified Gompertz equation and the first order equation. Analysis of Spearman's rank correlation coefficients revealed a statistically significant relationship between the kinetic parameters of H 2 production and the concentration of butyrate and the final pH of the medium for C. butyricum SP4, and with the concentration of ethanol for C. beijerinckii SP6. These findings provide valuable information on the metabolic capabilities of the most studied hydrogen-producing representatives of the Clostridium genus for their use in optimizing the technology for biohydrogen production by dark fermentation of various organic wastes. [ABSTRACT FROM AUTHOR]

Hemicelluloses are a major component of lignocellulosic biomass. Different sugars can be obtained from hemicelluloses: xylose, arabinose, galactose, mannose, glucose. Their catalytic hydrogenation produces polyols: xylitol, arabinitol, dulcitol, mannitol, sorbitol, which are valuable chemicals and platform molecules. In this paper, the hydrogenation of sugars was investigated with a Ru/TiO2 catalyst. The influence of temperature, pressure, xylose concentration and catalyst amount was studied for xylose hydrogenation and a Langmuir‐Hinshelwood kinetic model was designed. The comparative study of five hemicellulose sugars showed a strong impact of sugar structure on hydrogenation rate: hexoses (glucose, mannose, galactose) react slower than pentoses (xylose, arabinose). [ABSTRACT FROM AUTHOR]

Biorefineries are facilities in which lignocellulosic biomasses are converted in a wide range of bioproducts facilitating the transition from the use of petrochemical resources to renewable ones. Organic acids are considered very attractive for their utilization in different industrial areas as building blocks or as final bioproducts leading to a considerable market growth. They are metabolites which are naturally produced by microbials. The production of these molecules by filamentous fungi are attracting more attention due to their ability to hydrolyze lignocellulosic biomasses and to contextually produce different organic acids. Contrarily to a lot of other microorganisms, fungi have the ability to ferment pentoses, broadening the substrate utilization. The integrated use of lignocellulosic biomasses as material input and fungi as biocatalyst can contribute to make biorefineries more successful. This review gives an overview about the lignocellulosic biomass structure and hydrolysis, fungal morphology, and how they are connected. Further, it describes some relevant organic acids with regard to their processes, biocatalysts, industrial applications, and market considerations. [ABSTRACT FROM AUTHOR]

Saccharomyces cerevisiae (S. cerevisiae) is the most widely used yeast in biotechnology in the world because its well-known metabolism and physiology as well as its recognized ability to ferment sugars such as hexoses. However, it does not metabolize pentoses such as arabinose and xylose, which are present in lignocellulosic biomass. Lignocellulose is a widely available raw material, with xylose content of approximately 35% of total sugars. This xylose fraction could be used to obtain high added-value chemical products such as xylitol. One of these yeasts isolated from a Colombian locality, designated as 202-3, showed interesting properties. 202-3 was identified through different approaches as a strain of S. cerevisiae, with an interesting consumption of xylose metabolizing into xylitol, in addition with excellent ability as a hexose fermenter with high ethanol yields and shows resistance to inhibitors present in lignocellulosic hydrolysates. The xylose metabolization by the 202-3 strain and their kinetics parameters had not been previously reported for any other natural strain of S. cerevisiae. These results suggest the great potential of natural strains for obtaining high value-added chemical products using sugars available in lignocellulosic biomass. [ABSTRACT FROM AUTHOR]

Different fractions of organic matter in surface sediments from three transects along the eastern margin of the Arabian Sea (AS) were quantified to determine the sources of organic matter, and also to study its impact on microbial community structure. From the extensive analyses of different biochemical parameters, it was evident that the distribution of total carbohydrate (TCHO), total neutral carbohydrate (TNCHO), proteins, lipids, and uronic acids (URA) concentrations and yield (% TCHO-C/TOC) are affected by organic matter (OM) sources and microbial degradation of sedimentary OM. Monosaccharide compositions from surface sediment was quantified to assess the sources and diagenetic fate of carbohydrates, suggesting that the deoxysugars (rhamnose plus fucose) had significant inverse relationship (r = 0.928, n = 13, p < 0.001) with hexoses (mannose plus galactose plus glucose) and positive relationship (r = 0.828, n = 13, p < 0.001) with pentoses (ribose plus arabinose plus xylose). This shows that marine microorganisms are the source of carbohydrates and there is no influence of terrestrial OM along the eastern margin of AS. During the degradation of algal material, the hexoses seem to be preferentially used by heterotrophic organisms in this region. Arabinose plus galactose (glucose free wt %) values between 28 and 64 wt% indicate that OM was derived from phytoplankton, zooplankton, and non-woody tissues. In the principal component analysis, rhamnose, fucose, and ribose form one cluster of positive loadings while glucose, galactose, and mannose form another cluster of negative loadings which suggest that during OM sinking process, hexoses were removed resulting in increase in bacterial biomass and microbial sugars. Results indicate sediment OM to be derived from marine microbial source along the eastern margin of AS. [ABSTRACT FROM AUTHOR]

Cutaneotrichosporon oleaginosus is a highly efficient single cell oil producer, which in addition to hexoses and pentoses can metabolize organic acids. In this study, fed-batch cultivation with consumption-based acetic acid feeding was further developed to integrate the transformation of an industrial paper mill lignocellulosic hydrolysate (LCH) into yeast oil. Employing pentose-rich LCH as a carbon source instead of glucose significantly improved both biomass formation and lipid titer, reaching 55.73 ± 5.20 g/L and 42.1 ± 1.7 g/L (75.5% lipid per biomass), respectively. This hybrid approach of using acetic acid and LCH in one process was further optimized to increase the share of bioavailable carbon from LCH using a combination of consumption-based and continuous feeding. Finally, the techno-economic analysis revealed a 26% cost reduction when using LCH instead of commercial glucose. In summary, we developed a process leading to a holistic approach to valorizing a pentose-rich industrial waste by converting it into oleochemicals. [ABSTRACT FROM AUTHOR]

This study aimed to perform genomic, probiotic, and metabolic characterization of a novel Liquorilactobacillus nagelii AGA58 isolated from a lactic acid-fermented shalgam beverage to understand its metabolic potentials and probiotic features. AGA58 is gram-positive, motile, catalase-negative and appears as short rods under the light-microscope. The AGA58 chromosome comprises a single linear chromosome of 2,294,635 bp that is predicted to carry 2135 coding sequences, including 45 tRNA genes, 3 mRNA, and 3 rRNA operons. The genome has a G+C content of 36.9%, including 55 pseudogenes and a single intact prophage. AGA58 is micro-anaerobic due to achieving a shorter doubling time and faster growth rate than micro-aerophilic conditions. It carries flagellar biosynthesis protein-encoding genes predicting motile behavior, which was confirmed with the in vitro motility test. AGA58 is an obligatory homofermentative lactobacillus that can ferment hexose sugars such as galactose, glucose, fructose, sucrose, mannose, N -acetyl glucosamine, maltose, and trehalose to lactate through glycolysis. No acid production from pentoses implies that five-carbon sugars are being utilized for purine and pyrimidine synthesis. Putative pyruvate metabolism revealed formate, malate, oxaloacetate, acetate, acetaldehyde, acetoin, and lactate forms from pyruvate. AGA58 is predicted to encode the LuxS gene and biosynthesis of class IIa and Blp family class-II bacteriocins suggesting this bacterium's antimicrobial potential, linked to antagonism tests that AGA58 can inhibit Escherichia coli ATCC 43895, S almonella enterica serovar Typhimurium ATCC 14028, and K lebsiella pneumonia ATCC 13883. Moreover, AGA58 is tolerant to acid and bile concentrations simulating the human gastrointestinal conditions depicting the probiotic potential of the organism as the first report in literature within the same species. [ABSTRACT FROM AUTHOR]

In this study, the potential for a collection of wild-type L. lactis strains to metabolize the breakdown products of lignocellulose was investigated. The strains, isolated from a variety of environmental sources including grass and vegetables, were analyzed for their ability to ferment pentose sugars and their cellulolytic ability. In total, 21 environment-derived L. lactis strains were evaluated. Eleven of the 21 L. lactis isolates were found to have the potential to ferment pentose sugars commonly produced by lignocellulose breakdown. A 3,5-dinitrosalicylic acid (DNS)-based cellulase assay was performed, and 10 of the 21 L. lactis isolates showed cellulolytic activity. Six strains were able to both metabolize pentose sugars and showed cellulolytic activity: these included green pea isolates DPC 6754, DPC 6755, DPC 6756, and DPC 6758, the grass isolate DPC 6760, and the mung bean sprouts isolate KF147. For the first time, certain wild-type non-engineered L. lactis were found to possess cellulolytic activity. Moreover, these two abilities do not appear to be correlated. These findings highlight that environment-derived L. lactis, a species with a history of safe use in food production, has the potential for second-generation bioconversion processes, and the potential to re-utilize plant biomass found in waste streams. [ABSTRACT FROM AUTHOR]

The organic fraction of municipal solid waste (OFMSW) and refuse-derived fuel (RDF) mainly consisting of paper/cardboard can be used as feedstock for the production of cellulosic ethanol. In this paper, an efficient technology is described to convert waste paper/cardboard into cellulosic ethanol. The process involves separation of the OF from the other components in the waste stream. An acid pretreatment is used to liberate the cellulosic fibers and the accessibility of the enzyme Cellic CTEC3 loading 3.75–11.25 FPU/g paper in a fed-batch addition up to 22.5% solid yield, 15 g sugars/l with a saccharification yield up to 90%. A semi-simultaneous fermentation process (SSFP) with a saccharomyces cerevisae strain MDS130 capable of fermenting both pentoses and hexoses are growing an ethanol titer (%v/v) of 8.4% on pilon-plant scale. [ABSTRACT FROM AUTHOR]

Trihydroxypiperidines are a therapeutically valuable class of iminosugar. We applied a one-pot amination-cyclisation cascade reaction to synthesise 3,4,5-trihydroxypiperidine stereoisomers in three steps from commercially available pentoses and in excellent overall yields. Using our methodology, the yields of the syntheses of meso -1, meso -2 and 3L are the highest reported to date. The synthetic methodology was readily extended to the three-step synthesis of N -alkyl derivatives by replacing the ammonia nitrogen source with a primary amine. The trihydroxypiperidines and N -alkyl analogues were screened for enzyme inhibitory activity using Fabrazyme (Fabry disease), GCase (Gaucher's disease), Agrobacterium sp. β-glucosidase, and Escherichia coli β-galactosidase. N -Phenylethyl 3,4,5-trihydroxypiperidine (N -phenylethyl-1-(3 R ,4 R ,5 S)-piperidine-3,4,5-triol) showed good inhibitory activity of Fabrazyme (K i = 46 μM). This activity was abolished when the N -phenylethyl group was removed or replaced with a non-aromatic alkyl chain. [Display omitted] • Trihydroxypiperidine stereoisomers synthesised using one-pot cyclisation cascade. • Method extends to the synthesis of N -alkyl 3,4,5-trihydroxypiperidine derivatives. • Trihydroxypiperidines synthesised from chiral pool starting materials in good overall yields. • Good inhibitory activity of Fabrazyme by N -phenylethyl-1-(3 R ,4 R ,5 S)-piperidine-3,4,5-triol. [ABSTRACT FROM AUTHOR]

Parageobacillus thermoglucosidasius is a thermophilic bacterium of interest for lignocellulosic biomass fermentation. However, carbon catabolite repression (CCR) hinders co-utilization of pentoses and hexoses in the biomass substrate. Hence, to optimize the fermentation process, it is critical to remove CCR in the fermentation strains with minimal fitness cost. In this study, we investigated whether CCR could be removed from P. thermoglucosidasius DSM 2542 by mutating the Ser46 regulatory sites on HPr and Crh to a non-reactive alanine residue. It was found that neither the ptsH1 (HPr-S46A) nor the crh1 (Crh-S46A) mutation individually eliminated CCR in P. thermoglucosidasius DSM 2542. However, it was not possible to generate a ptsH1 crh1 double mutant. While the Crh-S46A mutation had no obvious fitness effect in DSM 2542, the ptsH1 mutation had a negative impact on cell growth and sugar utilization under fermentative conditions. Under these conditions, the ptsH1 mutation was associated with the production of a brown pigment, believed to arise from methylglyoxal production, which is harmful to cells. Subsequently, a less directed adaptive evolution approach was employed, in which DSM 2542 was grown in a mixture of 2-deoxy-D-glucose(2-DG) and xylose. This successfully removed CCR from P. thermoglucosidasius DSM 2542. Two selection strategies were applied to optimize the phenotypes of evolved strains. Genome sequencing identified key mutations affecting the PTS components PtsI and PtsG, the ribose operon repressor RbsR and adenine phosphoribosyltransferase APRT. Genetic complementation and bioinformatics analysis revealed that the presence of wild type rbsR and apt inhibited xylose uptake or utilization, while ptsI and ptsG might play a role in the regulation of CCR in P. thermoglucosidasius DSM 2542. [ABSTRACT FROM AUTHOR]

An iron-catalysed transfer hydrogenation methodology was developed to oxidise aldo-hexoses and -pentoses into sugar lactones using different acceptors. The transformation occurs on unprotected sugars with complete chemo-selectivity for the anomeric position. An application for the competitive oxidation of pentose from a mixture of C5 and C6 sugars is also reported. Finally, we managed to perform the oxidation of xylose with only an equimolar amount of a carefully chosen acceptor, improving drastically the sustainability of the transformation without compromising the equilibrium shift. [ABSTRACT FROM AUTHOR]

Purpose: Mucilage plays crucial roles in root-soil interactions. Collection systems for maize (Zea mays L.) use primary and seminal roots of aeroponically-grown seedlings (CSA), or brace roots of soil-grown plants (CSB). While each method represents specific plant developmental stages, and root types growing in specific (micro-)environments, these factors are rarely considered. It is unclear whether mucilage exhibits distinct physico-chemical properties related to collection system-inherent factors. Methods: Mucilage of maize genotype B73 was collected from systems CSA and CSB. Chemical composition was assessed by pH, nutrient contents, neutral sugar composition, and polysaccharide polymer length. Viscosity, surface tension and contact angle represented physical properties. Results: The share of hexoses among total polysaccharides was 11% higher in CSB than in CSA, whereas pentoses were predominant in CSA, together with higher nutrient concentrations and pH values. Mannose was detected only in CSB, which also exhibited higher surface tension, viscosity and contact angle compared to CSA. Conclusions: Physico-chemical differences between the two mucilages are related to root type functions, environmental root growth conditions, and plant developmental state. Higher fractions of pentoses in CSA mucilage seem related to semi-sterile system conditions. Higher viscosity of CSB mucilage might reflect the need for enhanced water holding capacity of brace roots growing in drier conditions. A strong influence of environmental factors on mucilage properties even for a single genotype might play additional roles e.g. in the attraction of microbiomes. These aspects are relevant when assessing the role of mucilage in the rhizosphere, or when developing models of rhizosphere processes. [ABSTRACT FROM AUTHOR]

The production of second-generation (2G) ethanol remains an interesting proposition for the implementation of sustainable and net carbon–neutral energy systems. To be economically viable, 2G biorefineries must make use of all processing streams, including the less desirable pentose (C5) sugar stream. In this work, a strategy of sequential dilute acid and alkaline pretreatment of the lignocellulosic feedstock, switchgrass, was implemented for improving the fermentable sugar yield. The hemicellulose-enriched hydrolysate obtained after dilute acid pretreatment was fermented by a newly isolated wild Scheffersomyces parashehatae strain—UFMG-HM-60.1b; the corresponding ethanol yield (YPS) and volumetric productivity (QP) were 0.19 g/g and 0.16 g/L h, respectively. The remaining switchgrass cellulignin fraction was subjected to optimized alkaline delignification at 152 ºC for 30 min. Then, the delignified solid fraction was subjected to contiguous enzymatic saccharification and fermentation releasing a glucose (C6) sugar stream. The control yeast strain, Saccharomyces cerevisiae 174, displayed an ethanol YPS of 0.46 g/g and QP of 0.70 g/L h for the C6 sugar stream, whereas the above-mentioned wild strain presented YPS and QP of 0.29 g/g and 0.38 g/L h, respectively. Upon combining the conversion of hemicellulose (37%) and cellulose-derived sugars (57%), the wild S. parashehatae strain provided higher yield (94%) than the generic S. cerevisiae (90%). Henceforth, our sequential two-stage pretreatment and fermentation of C5 and C6 sugar streams provides a pathway for maximum utilization of switchgrass carbohydrates for 2G ethanol production. [ABSTRACT FROM AUTHOR]

d-Tagatose, a functional sweetener, is converted from d-galactose by l-arabinose isomerase, which catalyzes the conversion of l-arabinose to l-ribulose. In this study, the araA gene encoding l-arabinose isomerase from Klebsiella pneumoniae was cloned and expressed in Escherichia coli, and the expressed enzyme was purified and characterized. The purified l-arabinose isomerase, a soluble protein with 11.6-fold purification and a 22% final yield, displayed a specific activity of 1.8 U/mg for d-galactose and existed as a homohexamer of 336 kDa. The enzyme exhibited maximum activity at pH 8.0 and 40 °C in the presence of Mn2+ and relative activity for pentoses and hexoses in the order l-arabinose > d-galactose > l-ribulose > d-xylulose > d-xylose > d-tagatose > d-glucose. The thermal stability of recombinant E. coli cells expressing l-arabinose isomerase from K. pneumoniae was higher than that of the enzyme. Thus, the reaction conditions of the recombinant cells were optimized to pH 8.0, 50 °C, and 4 g/L cell concentration using 100 g/L d-galactose with 1 mM Mn2+. Under these conditions, 33.5 g/L d-tagatose was produced from d-galactose with 33.5% molar yield and 67 g/L/h productivity. Our findings will help produce d-tagatose using whole-cell reactions, extending its industrial application. [ABSTRACT FROM AUTHOR]

Lignocellulosic biomass residues constitute an alternative for energy generation. In this work, brewery spent grain (BSG) were used as feedstock to produce ethanol using a recombinant Escherichia coli MS04 strain. A sequential process involving pretreatment, saccharification and fermentation steps in one-pot bioreactors, without solids removal, was proposed. Different diluted acid pretreatment times (1 and 1.5 h) using a 15% (w/w) solids load to obtain high monosaccharides yields were evaluated. After the pretreatment and saccharification, the proposed strategy converted the polysaccharides contained in BSG into fermentable pentoses and hexoses, obtaining a syrup composed by monosaccharides (60 g/L), furfural (0.39 g/L), hydroxymethylfurfural (0.07 g/L) and acetic acid (2.56 g/L), which was afterwards fermented for the bioethanol generation. After 30 h, ethanol production resulted in 29.5 ± 0.41 g/L, which means a volumetric productivity of 0.98 g EtOH/Lh based on the consumption of the glucose, xylose and arabinose. These results mean a global yield of 251 L EtOH/ton BSG of this feedstock and were accomplished without the inhibition caused by acetic acid formation (6.87 g/L). Furthermore, the proposed process in this work was developed in a sequential pathway, which comprises an operational advantage to exploit the BSG in the production of second-generation bioethanol. [Display omitted] [ABSTRACT FROM AUTHOR]

Lignocellulosic waste is the most abundant global renewable biomass source and contains significant amounts of pentoses. Thus, pentoses can be considered potential carbon sources for the culture media for microalgae cultivation. The present study aimed to determine whether the addition of D‐xylose and L‐arabinose and lighting variations influence the carbohydrate and protein profiles of Chlorella minutissima grown in tubular photobioreactors. The highest biomass concentration of 1.55 g L−1 was attained by the control cultures exposed to a light intensity of 40.50 μmol m−2 s−1. The highest carbohydrate accumulation (66.4%) was obtained through the combined use of 40.50 μmol m−2 s−1 light intensity, 19.16 mg L−1 D‐xylose, 0.89 mg L−1 L‐arabinose, and 0.125 g L−1 KNO3. A reduction in luminosity and the addition of pentoses altered the protein profile of Chlorella minutissima. Thus, growth and carbohydrate production can be stimulated by pentoses and adequate luminous intensity. Therefore, Chlorella minutissima can be considered a potential source of biomass for bioethanol production. [ABSTRACT FROM AUTHOR]

The simultaneous production of hydrogen and biomass-based chemicals from biomass-derived feedstock aqueous solutions via photocatalysis is appealing because no additional sacrificial agent is needed. However, limited success has been achieved. This paper reports efficient nori-shaped carbon nitride-based photocatalysts with potassium/oxygen co-doping and cyano group introduction for efficient conversion of biomass-derived monosaccharides to produce lactic acid and hydrogen simultaneously. The obtained photocatalyst has an adjustable bandgap, fast migration/separation rate of photo-generated carriers and displays excellent photocatalytic performance with respect to xylose conversion (∼95.0%), lactic acid selectivity (90.5%) and hydrogen generation (∼33 380 μmol g−1 h−1) in the presence of visible light. The h+, ˙OH, ˙O2− and 1O2 drive xylose conversion and lactic acid production. For biomass-derived pentoses and hexoses, the reaction system also exhibits excellent photocatalytic activity of lactic acid selectivity and hydrogen generation; the reported photocatalyst has excellent reusability. This paper provides a new perspective for hydrogen generation and biorefineries via a photocatalyst. [ABSTRACT FROM AUTHOR]

The origin of life might be sparked by the polymerization of the first RNA molecules in Darwinian ponds during wet-dry cycles. The key life-building block ribose was found in carbonaceous chondrites. Its exogenous delivery onto the Hadean Earth could be a crucial step toward the emergence of the RNA world. Here, we investigate the formation of ribose through a simplified version of the formose reaction inside carbonaceous chondrite parent bodies. Following up on our previous studies regarding nucleobases with the same coupled physico-chemical model, we calculate the abundance of ribose within planetesimals of different sizes and heating histories. We perform laboratory experiments using catalysts present in carbonaceous chondrites to infer the yield of ribose among all pentoses (5Cs) forming during the formose reaction. These laboratory yields are used to tune our theoretical model that can only predict the total abundance of 5Cs. We found that the calculated abundances of ribose were similar to the ones measured in carbonaceous chondrites. We discuss the possibilities of chemical decomposition and preservation of ribose and derived constraints on time and location in planetesimals. In conclusion, the aqueous formose reaction might produce most of the ribose in carbonaceous chondrites. Together with our previous studies on nucleobases, we found that life-building blocks of the RNA world could be synthesized inside parent bodies and later delivered onto the early Earth. [ABSTRACT FROM AUTHOR]

Ribulose 1,5-bisphosphate carboxylase/oxygenase (RubisCO) is a critical yet severely inefficient enzyme that catalyses the fixation of virtually all of the carbon found on Earth. Here, we report a functional metagenomic selection that recovers physiologically active RubisCO molecules directly from uncultivated and largely unknown members of natural microbial communities. Selection is based on CO2 -dependent growth in a host strain capable of expressing environmental deoxyribonucleic acid (DNA), precluding the need for pure cultures or screening of recombinant clones for enzymatic activity. Seventeen functional RubisCO-encoded sequences were selected using DNA extracted from soil and river autotrophic enrichments, a photosynthetic biofilm and a subsurface groundwater aquifer. Notably, three related form II RubisCOs were recovered which share high sequence similarity with metagenomic scaffolds from uncultivated members of the Gallionellaceae family. One of the Gallionellaceae RubisCOs was purified and shown to possess CO2 /O2 specificity typical of form II enzymes. X-ray crystallography determined that this enzyme is a hexamer, only the second form II multimer ever solved and the first RubisCO structure obtained from an uncultivated bacterium. Functional metagenomic selection leverages natural biological diversity and billions of years of evolution inherent in environmental communities, providing a new window into the discovery of CO2 -fixing enzymes not previously characterized.

As abundant carbohydrates in renewable feedstocks, such as pectin-rich and lignocellulosic hydrolysates, the pentoses arabinose and xylose are regarded as important substrates for production of biofuels and chemicals by engineered microbial hosts. Their efficient transport across the cellular membrane is a prerequisite for economically viable fermentation processes. Thus, there is a need for transporter variants exhibiting a high transport rate of pentoses, especially in the presence of glucose, another major constituent of biomass-based feedstocks. Here, we describe a variant of the galactose permease Gal2 from Saccharomyces cerevisiae (Gal2N376Y/M435I), which is fully insensitive to competitive inhibition by glucose, but, at the same time, exhibits an improved transport capacity for xylose compared to the wildtype protein. Due to this unique property, it significantly reduces the fermentation time of a diploid industrial yeast strain engineered for efficient xylose consumption in mixed glucose/xylose media. When the N376Y/M435I mutations are introduced into a Gal2 variant resistant to glucose-induced degradation, the time necessary for the complete consumption of xylose is reduced by approximately 40%. Moreover, Gal2N376Y/M435I confers improved growth of engineered yeast on arabinose. Therefore, it is a valuable addition to the toolbox necessary for valorization of complex carbohydrate mixtures. [ABSTRACT FROM AUTHOR]

Vine shoots (Vitis vinifera L.) constitute an abundant lignocellulosic source which is frequently underutilised. Alkaline and acidic pretreatments (with and without washing steps) were compared and optimised to release fermentable sugars from vine shoots. An acidic pretreatment using 1.72% H2SO4 at 134 °C for 17 min (with 10% w/w solid biomass), followed by an enzymatic hydrolysis, offered the most cost-effective results, releasing 40.21 g/L sugars. Three thermotolerant strains, namely, Bacillus coagulans DSM 2314, Geobacillus stearothermophilus DSM 2313, and G. stearothermophilus DSM 494, were assessed to produce lactic acid from vine-shoot hydrolysates under aerobic and non-sterile conditions, without the need of detoxification steps. In addition, wine lees were satisfactorily employed as nitrogen sources for the fermentation, providing similar results to yeast extract and being the only nutrient added to vine-shoot hydrolysates. Under optimal conditions, B. coagulans DSM 2314 produced 29.21 ± 0.23 g/L lactic acid in 24 h, with a sugar consumption of 98.74 ± 0.07% and a yield of 96.38 ± 0.76%, when supplemented with red wine lees. The purity of the isomer L(+) reached 97.59 ± 1.35% of the total lactic acid produced. Although G. stearothermophilus was able to transform the hexoses from vine-shoot hydrolysates into lactic acid, it proved to be inefficient for metabolising pentoses, thus obtaining lower lactic acid values (16–18 g/L). [ABSTRACT FROM AUTHOR]

Biomass alkaline deacetylation prior to acid pretreatment can be a promising alternative to reduce the toxicity of hemicellulosic hydrolysates and improve second-generation bioethanol production. In this paper, the effect of alkaline deacetylation of sugarcane bagasse on bioethanol production by Spathaspora passalidarum was evaluated. Sugarcane bagasse deacetylated hemicellulosic hydrolysate (DHH) was processed using the following sequence: (1) deacetylation (0.4%, w/v NaOH, 70 °C, 3 h) and (2) acid pretreatment (0.5% (v/v) of H2SO4, 140 °C, 15 min). Non-deacetylated, hemicellulosic hydrolysate (HH), was obtained applying only acid pretreatment (0.5% (v/v) of H2SO4, 140 °C, 15 min). Biomass deacetylation reduced the content of acetic acid and some phenolic compounds in the hydrolysate (DHH) compared to acid pretreatment (HH), which resulted in its low toxicity. Thus, the bioethanol production with DHH was of 16.92 g L−1, whereas only 1.3 g L−1 of bioethanol was obtained with HH fermentation. Deacetylation process provided a 13-fold increase in bioethanol production by S. passalidarum, showing that alkaline deacetylation followed by sulfuric acid pretreatment is a promising strategy to increase bioethanol production. This procedure provided a simple and practical alternative to the classic methods of detoxification of hemicellulosic hydrolysate from sugarcane bagasse. [ABSTRACT FROM AUTHOR]

Bioconversion of hemicelluloses into simpler sugars leads to the production of a significant amount of pentose sugars, such as D-xylose. However, efficient utilization of pentoses by conventional yeast production strains remains challenging. Wild yeast strains can provide new industrially relevant characteristics and efficiently utilize pentose sugars. To explore this strategy, we isolated gut-residing yeasts from the termite Macrotermes bellicosus collected in Comoe' National Park, Côte d'Ivoire. The yeasts were classified through their Internal Transcribed Spacer/Large Subunit sequence, and their genomes were sequenced and annotated. We identified a novel yeast species, which we name Barnettozyma botsteinii sp. nov. 1118T (MycoBank: 833563, CBS 16679T and IBT 710) and two new strains of Kurtzmaniella quercitrusa: var. comoensis (CBS 16678, IBT 709) and var. filamentosus (CBS 16680, IBT 711). The two K. quercitrusa strains grow 15% faster on synthetic glucose medium than Saccharomyces cerevisiae CEN.PKT in acidic conditions (pH = 3.2) and both strains grow on D-xylose as the sole carbon source at a rate of 0.35 h-1. At neutral pH, the yeast form of K. quercitrusa var. filamentosus, but not var. comoensis, switched to filamentous growth in a carbon source-dependent manner. Their genomes are 11.0-13.2Mb in size and contain between 4888 and 5475 predicted genes. Together with closely related species, we did not find any relationship between gene content and ability to grow on xylose. Besides its metabolism, K. quercitrusa var. filamentosus has a large potential as a production organism, because of its capacity to grow at low pH and to undergo a dimorphic shift. [ABSTRACT FROM AUTHOR]

Herbaspirillum seropedicae is a β-proteobacterium that establishes as an endophyte in various plants. These bacteria can consume diverse carbon sources, including hexoses and pentoses like d-xylose. d-xylose catabolic pathways have been described in some microorganisms, but databases of genes involved in these routes are limited. This is of special interest in biotechnology, considering that d-xylose is the second most abundant sugar in nature and some microorganisms, including H. seropedicae, are able to accumulate poly-3-hydroxybutyrate when consuming this pentose as a carbon source. In this work, we present a study of d-xylose catabolic pathways in H. seropedicae strain Z69 using RNA-seq analysis and subsequent analysis of phenotypes determined in targeted mutants in corresponding identified genes. G5B88_22805 gene, designated xylB, encodes a NAD+-dependent d-xylose dehydrogenase. Mutant Z69∆xylB was still able to grow on d-xylose, although at a reduced rate. This appears to be due to the expression of an l-arabinose dehydrogenase, encoded by the araB gene (G5B88_05250), that can use d-xylose as a substrate. According to our results, H. seropedicae Z69 uses non-phosphorylative pathways to catabolize d-xylose. The lower portion of metabolism involves co-expression of two routes: the Weimberg pathway that produces α-ketoglutarate and a novel pathway recently described that synthesizes pyruvate and glycolate. This novel pathway appears to contribute to d-xylose metabolism, since a mutant in the last step, Z69∆mhpD, was able to grow on this pentose only after an extended lag phase (40–50 h). Key points: • xylB gene (G5B88_22805) encodes a NAD+-dependent D-xylose dehydrogenase. • araB gene (G5B88_05250) encodes a L-arabinose dehydrogenase able to recognize D-xylose. • A novel route involving mhpD gene is preferred for D-xylose catabolism. [ABSTRACT FROM AUTHOR]

Microbial metabolism can be harnessed to produce a large library of useful chemicals from renewable resources such as plant biomass. However, it is laborious and expensive to create microbial biocatalysts to produce each new product. To tackle this challenge, we have recently developed modular cell (ModCell) design principles that enable rapid generation of production strains by assembling a modular (chassis) cell with exchangeable production modules to achieve overproduction of target molecules. Previous computational ModCell design methods are limited to analyze small libraries of around 20 products. In this study, we developed a new computational method, named ModCell-HPC, that can design modular cells for large libraries with hundreds of products with a highly-parallel and multi-objective evolutionary algorithm and enable us to elucidate modular design properties. We demonstrated ModCell-HPC to design Escherichia coli modular cells towards a library of 161 endogenous production modules. From these simulations, we identified E. coli modular cells with few genetic manipulations that can produce dozens of molecules in a growth-coupled manner with different types of fermentable sugars. These designs revealed key genetic manipulations at the chassis and module levels to accomplish versatile modular cells, involving not only in the removal of major by-products but also modification of branch points in the central metabolism. We further found that the effect of various sugar degradation on redox metabolism results in lower compatibility between a modular cell and production modules for growth on pentoses than hexoses. To better characterize the degree of compatibility, we developed a method to calculate the minimal set cover, identifying that only three modular cells are all needed to couple with all compatible production modules. By determining the unknown compatibility contribution metric, we further elucidated the design features that allow an existing modular cell to be re-purposed towards production of new molecules. Overall, ModCell-HPC is a useful tool for understanding modularity of biological systems and guiding more efficient and generalizable design of modular cells that help reduce research and development cost in biocatalysis. • Develop a novel computational method to design modular cells compatible with hundreds of product synthesis modules. • Design three Escherichia coli modular cells that can couple growth with product synthesis of a total of 85 molecules. • Identify removal of major byproducts and modification of branch points in central metabolism as key interventions for modular cell designs. • Design E. coli modular cells utilizing hexoses and pentoses and identify the limitations of pentoses for growth-coupled product synthesis. • Determine compatibility of an existing modular cell with new production modules. [ABSTRACT FROM AUTHOR]

Lignocellulosic-based ethanol is a viable alternative to corn-based ethanol. However, the use of such feedstock is more complex than the use of sugar or starch due to the necessity for a pretreatment stage. Here we tested three pretreatment processes of oat straw: (1) submerged ozonation in water, (2) low temperature (40 °C) diluted sulphuric acid (DSA) and (3) room temperature diluted sulphuric acid/ozone mixture (SOM). A unique water/ozone reactor was designed and constructed to demonstrate the pretreatment processes. Results showed best lignin removal by the submerged ozonation pretreatment and consequently the highest sugar and ethanol yields. Despite the non-conventional low temperature, DSA pretreatment results had showed slight lower yields then ozonation, with degradation of hemicellulose to xylose, while SOM pretreatment showed the poorest results. DSA pretreatment would probably show industrial feasibility when pentoses fermenting abilities will be added. [Display omitted] • Comparison of three different pretreatment for ethanol production from oat straw. • Best lignin removal, saccharification and ethanol yields by submerged ozonation. • Saccharification: Ozonation after ozonation result in mostly glucose, highest ethanol. • Saccharification after 40 °C dilute sulphuric acid pentoses result in mostly pentose. • Combined ozonation and sulphuric acid poorest saccharification and ethanol yield. [ABSTRACT FROM AUTHOR]

Summary: Spirochetes of the genus Treponema are surprisingly abundant in termite guts, where they play an important role in reductive acetogenesis. Although they occur in all termites investigated, their evolutionary origin is obscure. Here, we isolated the first representative of 'termite gut treponemes' from cockroaches, the closest relatives of termites. Phylogenomic analysis revealed that Breznakiella homolactica gen. nov. sp. nov. represents the most basal lineage of the highly diverse 'termite cluster I', a deep‐branching sister group of Treponemataceae (fam. 'Termitinemataceae') that was present already in the cockroach ancestor of termites and subsequently coevolved with its host. Breznakiella homolactica is obligately anaerobic and catalyses the homolactic fermentation of both hexoses and pentoses. Resting cells produced acetate in the presence of oxygen. Genome analysis revealed the presence of pyruvate oxidase and catalase, and a cryptic potential for the formation of acetate, ethanol, formate, CO2 and H2 ‐ the fermentation products of termite gut isolates. Genes encoding key enzymes of reductive acetogenesis, however, are absent, confirming the hypothesis that the ancestral metabolism of the cluster was fermentative, and that the capacity for acetogenesis from H2 plus CO2 ‐ the most intriguing property among termite gut treponemes ‐ was acquired by lateral gene transfer. [ABSTRACT FROM AUTHOR]

Currently, pectins are widely used in the cosmetic, pharmaceutical, and food industries, mainly as texturizing, emulsifying, stabilizing, and gelling agents. Pectins are polysaccharides composed of a large linear segment of α-(1,4) linked d-galactopyranosyluronic acids interrupted by β-(1,2)-linked l-rhamnoses and ramified by short chains composed of neutral hexoses and pentoses. The characteristics and applications of pectins are strongly influenced by their structures depending on plant species and tissues but also extraction methods. The aim of this review is therefore to highlight the structures of pectins and the various methods used to extract them, including conventional ones but also microwave heating, ultrasonic treatment, and dielectric barrier discharge techniques, assessing physico-chemical parameters which have significant effects on pectin characteristics and applications as techno-functional and bioactive agents. [ABSTRACT FROM AUTHOR]

Spiculisporic acid (SA) is a fatty acid-type biosurfactant with one lactone ring and two carboxyl groups. It has been used in metal removers and cosmetics, because of its low propensity to cause irritation to the skin, its anti-bacterial properties, and high surface activity. In the present study, we report an effective method for producing SA by selecting a high-producing strain and investigating the effective medium components, conditions, and environments for its culture. Among the 11 kinds of Talaromyces species, T. trachyspermus NBRC 32238 showed the highest production of a crystalline substance, which was determined to be SA using NMR. The strain was able to produce SA under acidic conditions from hexoses, pentoses, and disaccharides, with glucose and sucrose serving as the most appropriate substrates. Investigation of nitrogen sources and trace metal ions revealed meat extract and FeCl3 as components that promoted SA production. Upon comparing the two types of cultures with glucose in a baffle flask or aeration bioreactor, SA production was found to be slightly higher in the flask than in the reactor. In the bioreactor culture, sucrose was found to be an appropriate substrate for SA production, as compared to glucose, because with sucrose, the lag time until the start of SA production was shortened. Finally, fed-batch culture with sucrose resulted in 60 g/L of SA, with a total yield of 0.22 g SA/g sucrose and a productivity of 6.6 g/L/day. [ABSTRACT FROM AUTHOR]

Pentose sugars are widespread in nature and two of them, D-xylose and L-arabinose belong to the most abundant sugars being the second and third by abundance sugars in dry plant biomass (lignocellulose) and in general on planet. Therefore, it is not surprising that metabolism and bioconversion of these pentoses attract much attention. Several different pathways of D-xylose and L-arabinose catabolism in bacteria and yeasts are known. There are even more common and really ubiquitous though not so abundant pentoses, D-ribose and 2-deoxy-D-ribose, the constituents of all living cells. Thus, ribose metabolism is example of endogenous metabolism whereas metabolism of other pentoses, including xylose and L-arabinose, represents examples of the metabolism of foreign exogenous compounds which normally are not constituents of yeast cells. As a rule, pentose degradation by the wild-type strains of microorganisms does not lead to accumulation of high amounts of valuable substances; however, productive strains have been obtained by random selection and metabolic engineering. There are numerous reviews on xylose and (less) L-arabinose metabolism and conversion to high value substances; however, they mostly are devoted to bacteria or the yeast Saccharomyces cerevisiae. This review is devoted to reviewing pentose metabolism and bioconversion mostly in non-conventional yeasts, which naturally metabolize xylose. Pentose metabolism in the recombinant strains of S. cerevisiae is also considered for comparison. The available data on ribose, xylose, L-arabinose transport, metabolism, regulation of these processes, interaction with glucose catabolism and construction of the productive strains of high-value chemicals or pentose (ribose) itself are described. In addition, genome studies of the natural xylose metabolizing yeasts and available tools for their molecular research are reviewed. Metabolism of other pentoses (2-deoxyribose, D-arabinose, lyxose) is briefly reviewed. [ABSTRACT FROM AUTHOR]

Objective: The effects of monosaccharide constituents of lignocellulosic materials on exopolysaccharide (EPS) production by Mesorhizobium sp. Semia 816 were studied. Results: According to the results, by using sugars commonly found in lignocellulosic biomass as carbon sources (glucose, arabinose and xylose), no significant differences were observed in the production of EPS, reaching 3.39 g/L, 3.33 g/L and 3.27 g/L, respectively. Differences were observed in monosaccharide composition, mainly in relation to rhamnose and glucuronic acid contents (1.8 times higher when arabinose was compared with xylose). However, the biopolymers showed no differences in relation to rheological properties, with EPS aqueous-based suspensions (1.0% w/v) presenting pseudoplastic behavior, and a slight difference in degradation temperatures. Using soybean hulls hydrolysate as carbon source, slightly higher values were obtained (3.93 g/L). Conclusion: The results indicate the potential of the use of lignocellulosic hydrolysates containing these sugars as a source of carbon in the cultivation of Mesorhizobium sp. Semia 816 for the production of EPS with potential industrial applications. [ABSTRACT FROM AUTHOR]

Bioethanol from lignocellulosic biomass (namely second-generation bioethanol) has been considered to be a great opportunity to increase production of biofuels from renewable sources without expanding the world planted area. Spathaspora passalidarum has shown great potential to convert sugars derived from lignocellulosic materials, which comprises hexoses and pentoses, into bioethanol. Besides its unusual ability to produce ethanol naturally from pentoses, this microorganism can also be used to obtain other products of interest. This review summarizes and discusses fermentative and kinetic parameters from the state of the art of ethanol production by S. passalidarum in synthetic medium and hemicellulosic hydrolysates. Additionally, S. passalidarum performance for xylose consumption and ethanol production are discussed in comparison with other wild yeasts and genetically modified Saccharomyces cerevisiae. In addition to ethanol, the production of other chemical blocks such as xylitol, glycerol, acetoin, and 2,3-butanediol are also discussed, elucidating the potential of S. passalidarum for application in biorefineries. The potential of S. passalidarum for studies of mutagenesis, evolutionary, and genetic modifications is also reviewed in this work. [ABSTRACT FROM AUTHOR]