Residual Carbohydrate Research Articles

Green preparations of nanolignin from acid-saccharification-treated sugarcane trash

Characterization of isolated lignin and utilization of nanotechnology to produce nanolignin as a functional material are paramount. Lignin was extracted from acid-saccharification sugarcane trash (SCT-ASac) to produce acid-saccharification lignin (ASac-lignin). Then, lignin was further processed to nanolignin by a self-assembly dialysis process using THF:ethanol (1:1) as the solvent. The chemical, physical, and thermal properties of the lignin were evaluated, and the nanolignin size was confirmed via morphological analysis and PSA. SCT-ASac treatment prior to lignin isolation affects the structure of SCT and enhances the accessibility of lignin. Furthermore, this pretreatment can reduce residual carbohydrates, increasing the purity value. ASac-lignin has a nonconjugated phenolic group structure with a high number of β-O-4 bonds, a syringyl content, aromatic groups with low thermal stability, and a molecular weight with good phenolic hydroxyl content and total phenolic compounds. The obtained nanolignin is a spherical and more uniform particle with sizes less than 100 nm. ASac-nanolignin has the potential to be an environmentally friendly material in derivative lignin synthesis.

Preparation and Characterization of Lignin Nanoparticles from Different Plant Sources.

This article presents new research on producing lignin nanoparticles (LNPs) using the antisolvent nanoprecipitation method. Acetone (90%) served as the lignin solvent and water (100%) as the antisolvent, using five types of lignins from various sources. Comprehensive characterization techniques, including NMR, GPC, FTIR, TEM, and DLS, were employed to assess both lignin and LNP properties. The antioxidant activity of the LNPs was evaluated as well. The results demonstrated the successful formation of spherical nanoparticles below 100 nm with initial lignin concentrations of 1 and 2%w/v. The study highlighted the crucial role of lignin purity in LNP formation and colloidal stability, noting that residual carbohydrates adversely affect efficiency. This method offers a straightforward, environmentally friendly approach using cost-effective solvents, applicable to diverse lignin sources. The innovation of this study lies in its demonstration of a cost-effective and eco-friendly method to produce stable, nanometric-sized spherical LNPs. These LNPs have significant potential as reinforcement materials due to their reinforcing capability, hydrophilicity, and UV absorption. This work underscores the importance of starting material purity for optimizing the process and achieving the desired nanometric dimensions, marking a pioneering advancement in lignin-based nanomaterials.

Determination of Thermal Conductivity Constant for Spray-Dried Mung Bean Protein Isolate using Series-Parallel “Block” Method and Central Composite Design

The efficient production of mung bean protein isolate (MBPI) is essential for sustainable food processing, yet it is energy-intensive due to drying phase required to convert raw mung beans into a fine powder. This work was carried out to calculate the thermal conductivity constant (k) of protein (A), moisture (B) and residual carbohydrate (C) of spray-dried MBPI. The protein slurry was prepared by dissolving MBPI in water at the ratio of 1:3, 1:4, and 1:5 prior to spray drying. The protein slurry was then spray dried at three different inflow temperatures of 140, 160, and 180 °C. A Series and Parallel Combination "Block" Model in tandem with a Central Composite Design (CCD) were selected to calculate the thermal conductivity constant of A, B and C. Eight arrangement components on A, B, and C component, measurements were derived from the initial three data points by utilizing the CCD method, in the preliminary study. By utilizing the series-parallel approach and statistical combination, there are a total of forty study arrangements. The thermal conductivity of MBPI with arrangements of A, B, and C (pABC); and a series of combinations of A and C in parallel to B (sAC pB) ranged from 0.1964-0.224 Wm-1 ℃ -1, with R2 = 98.73%-99.42%. Therefore, the energy requirement of spray drying process for MBPI could be predicted by the thermal properties of each component selected in the protein isolate.

NMR and Chemometrics in the Determination of Chemical Profiles for the Distinction of Brazilian Ale and Lager Beers

Determining chemical profiles of complex matrices, such as beers of different styles, can highlight regional characteristics and provide robust literature on the variability of this product, improving quality control. A practical application is to unequivocally attribute the authenticity of the product even in the face of variations in composition due to inadequate transport and storage. This work used proton nuclear magnetic resonance (1 H NMR) spectroscopy and chemometrics in the semi-quantitative study of Brazilian ale and lager beers. The results demonstrated the success of applying 1 H NMR in characterizing chemical profiles and as a statistical database to distinguish ale and lager beers. Using principal component analysis (PCA) of the NMR data, it was possible to identify that carbohydrate content was responsible for the separation tendency between these beer styles. Ale beers had a higher residual carbohydrate content, according to the integrals of the carbohydrate hydrogens. This is expected, as these beers are obtained by fermentation at higher temperatures for shorter fermentation times. The paper also described soft independent modelling of class analogies (SIMCA) as applied to the NMR data. This class model made it possible to correctly classify 90% of the samples as ale and 100% as lager.

Development and consumer acceptance testing of a honey-based beverage fermented by a multi-species starter culture

Despite being recognized as a risk factor for noncommunicable diseases (NCD), regular consumption of sugar-sweetened beverages (SSB) is promoted by the commercial interests of big business corporations and is not properly regulated by governments. To meet the demand for a healthier alternative to SSB, this study aimed to develop a honey-based fermented beverage and to evaluate its consumer acceptance. The top-down selection of bacteria and yeasts, isolated from six commercial symbiotic cultures and characterized in a honey-based experimental solution, was followed by the bottom-up construction of a defined multi-species starter culture. Plant extracts and bottle conditioning were used in a pilot-scale production for the sensory analysis of consumer acceptance with a three-domain questionnaire. Of the thirty-three isolated microorganisms, eleven did not grow on the honey-based broth, whereas eight were excluded for their excessive acidification. Two bacteria and three yeasts were carefully chosen for the multi-species starter culture employed in the pilot-scale production, resulting in a carbonated beverage without residual carbohydrates, no detectable acetic acid, 1.0 ± 0.1 g/L of lactic acid, 2.6 ± 0.3 g/L of glycerol and 5.4 ± 0.3 g/L of ethanol. Sensory beverage analysis by a hundred and twelve potential consumers revealed an eighty-six percent acceptance index. These results suggest that the developed beverage is well accepted, even having no sugar content and no chemical additives, being a promising alternative to hyper-caloric ultra-processed beverages.

Dextrose, maltose and starch guide crystallization of strontium-substituted hydroxyapatite: A comparative study for bone tissue engineering application

The influence of carbohydrates on the crystallization of metal-substituted hydroxyapatite predicts its relevance to natural bone growth. This study demonstrates the role of carbohydrates in the crystallization of strontium-substituted hydroxyapatite (SHAP). The increasing order of hydroxyl groups, dextrose (monosaccharide) < maltose (disaccharide) < starch (polysaccharide), coordinated with Ca2+/Sr2+ and thus guided SHAP crystallization, with crystal size reduced from 35 to 19 nm, lattice volume increased from 518 to 537 Å3, and residual carbohydrates increased from 1.8 to 20.2 %. The variation in residual carbohydrates is due to their interaction with apatite and/or aqueous insolubility. Compared to pure SHAP, the starch-SHAP with higher residual starch showed increased water uptake from 1.23 ± 0.18 to 4.26 ± 0.21 % and degradation from 0.22 ± 0.06 to 1.53 ± 0.14 %, but decreased microhardness from 0.73 ± 0.12 to 0.38 ± 0.01 GPa and protein affinity from 4.82 ± 0.01 to 0.81 ± 0.01 μg/mg. However, its microhardness value was bone-like, and the reduced protein adsorption was masked by the rich osteogenic behaviour. In vitro cellular response demonstrated that the residual carbohydrate and strontium augmented osteocompatibility, proliferation, differentiation and biomineralization. The result concludes that carbohydrates drive SHAP crystallization, and starch-SHAP replicates natural bone.

Effect of operational parameters on the performance of an anaerobic sequencing batch reactor (AnSBR) treating protein-rich wastewater

Treating protein-rich wastewater using cost-effective and simple-structured single-stage reactors presents several challenges. In this study, we applied an anaerobic sequencing batch reactor (AnSBR) to treat protein-rich wastewater from a slaughterhouse. We focused on identifying the key factors influencing the removal of chemical oxygen demand (COD) and the settling performance of the sludge. The AnSBR achieved a maximum total COD removal of 90%, a protein degradation efficiency exceeding 80%, and a COD to methane conversion efficiency of over 70% at organic loading rates of up to 6.2 g COD L−1 d−1. We found that the variations in both the organic loading rate within the reactor and the hydraulic retention time in the buffer tank had a significant effect on COD removal. The hydraulic retention time in the buffer tank and the reactor, which determined the ammonification efficiencies and the residual carbohydrate concentrations in the reactor liquid, affected the sludge settleability. Furthermore, the genus Clostridium sensu stricto 1, known as protein- and lipids-degraders, was predominant in the reactor. Statistical analysis showed a significant correlation between the core microbiome and ammonification efficiency, highlighting the importance of protein degradation as the governing process in the treatment. Our results will provide valuable insights to optimise the design and operation of AnSBR for efficient treatment of protein-rich wastewater.

Plant Genotype and Fungal Strain Harmonization Improves Miscanthus sinensis Conversion by the White-Rot Fungus Ceriporiopsis subvermispora

Fungal pretreatment of plant biomass is often assessed by using single plant genotypes and single fungal strains, but can the process be improved by harmonizing both, thus selecting specific substrate–fungus combinations? To tackle this question, we treated four Miscanthus sinensis genotypes with four Ceriporiopsis subvermispora strains and thoroughly analyzed substrates and treated residues. The M. sinensis genotypes differed in cellulose, hemicellulose, and lignin contents and lignin-wise diverged in subunit and linkage composition and the incorporation of hydroxycinnamic acids and tricin. Independently of the M. sinensis genotype used, C. subvermispora strain MES13904 outperformed the other three strains in extent and selectivity of delignification and consistently generated the highest enzymatic residual carbohydrate conversion and structural changes in the residual lignin. The “best” substrate–fungus combination gave 63% w/w delignification and a total enzymatic glucose yield of 66% w/w, while the “worst” combination led to 3% w/w lignin removal only and negligible glucose yield improvement. Our study highlights that white-rot fungal treatment of plant biomass is driven by both compositional and structural features of the substrate as well as the genetic makeup of the fungal strain used. These insights contribute to expediting the biological valorization of lignocellulose and ultimately to enabling more controlled fungal pretreatments.

In vitro fermentation characteristics of oxidized konjac glucomannan and its modulation effects on gut microbiota

Depolymerized konjac glucomannan (KGM) had better health benefits than natural KGM. Oxidation and enzyme-hydrolysis were two effective ways to prepare depolymerized KGM. Oxidized KGM (OKGM) and enzyme-hydrolyzed KGM (EKGM) varied in molecular structures, verified by nuclear magnetic resonance and atomic force microscope. The differences in chemical structure definitely influenced the fermentability of depolymerized KGM. Herein, effects of OKGM on in vitro fecal fermentation was investigated, comparing with EKGM at approximately same molecular weights. During fermentation, OKGM groups displayed slightly lower reducing sugar concentrations and higher residual carbohydrate contents than EKGM groups. After fermentation, OKGM groups produced more acetic acids and propionic acids than EKGM groups, while EKGM groups generated more butyric acids than OKGM groups. Meanwhile, relative abundances of the Firmicutes and Lactobacillus in OKGM groups were higher, while relative abundances of the Actinobacteria, Fusobacteria and Bacteroides was higher in EKGM groups. OKGM and EKGM differed in modulating gut microbiota.

Fractionation of Technical Lignin from Enzymatically Treated Steam-Exploded Poplar Using Ethanol and Formic Acid.

Lignocellulosic biorefineries produce lignin-rich side streams with high valorization potential concealed behind their recalcitrant structure. Valorization of these residues to chemicals, materials, and fuels increases the profitability of biorefineries. Fractionation is required to reduce the lignins' structural heterogeneity for further processing. We fractionated the technical biorefinery lignin received after steam explosion and saccharification processes. More homogeneous lignin fractions were produced with high β-O-4' and aromatic content without residual carbohydrates. Non-toxic biodegradable organic solvents like ethanol and formic acid were used for fractionation and can be adapted to the existing biorefinery processes. Macromolecular properties of the isolated fractions were carefully characterized by structural, chemical, and thermal methods. The ethanol organosolv treatment produced highly soluble lignin with a reasonable yield, providing a uniform material for lignin applications. The organosolv fractionation with formic acid and combined ethanol-formic acid produced modified lignins that, based on thermal analysis, are promising as thermoresponsive materials.

Development of Water Repellent, Non-Friable Tannin-Furanic-Fatty Acids Biofoams.

Tannin-furanic foams were prepared with a good yield using the addition of relatively small proportions of a polyflavonoid tannin extract esterified with either palmitic acid, oleic acid, or lauric acid by its reaction with palmitoyl chloride, oleyl chloride, or lauryl chloride. FTIR analysis allowed us to ascertain the esterification of the tannin, and MALDI-TOF analysis allowed us to identify a number of multi-esterified flavonoid oligomers as well as some linked to residual carbohydrates related to the equally esterified tannin. These foams presented a markedly decreased surface friability or no friability at all, and at densities lower than the standard foam they were compared to. Equally, these experimental foams presented a much-improved water repellence, as indicated by their initial wetting angle, its small variation over time, and its stabilization at a high wetting angle value, while the wetting angle of the standard foam control went to zero very rapidly. This conclusion was supported by the calculation of the total surface energy of their surfaces as well as of their dispersive and polar components.

Valorization of pretreated biogas digestate with black soldier fly (Hermetia illucens, L; Diptera: Stratiomyidae) larvae

Increasing concerns related to the negative environmental impacts of food waste havemotivated the development of new solutions to complete the waste cycle of organic residues. One particular "waste" product, the solid digestate from anaerobic digestion, has been identified for further bioprocessing. Black soldier fly (BSF, Hermetia illucens) larvae are known for their great potential in the processing of organic waste. In this study, this potential was investigated to further process the digestate waste stream. Digestate is considered a low potential source of nutrients for larvae due to the presence of different fiber fractions. However, the lignocellulosic matter in this residue could be enzymatically hydrolyzed to release residual carbohydrates. For this study, digestate from a full-scale anaerobic digestion plant in Quebec (Canada) which processes a range of feedstocks (fruits, vegetables, garden wastes, sludge derived from dairy processing and wastewater treatment) was sourced. Digestate was treated with Accelerase® DUET enzyme complex to hydrolyze lignocellulosic matter and compared to a standard diet. For each treatment, 600 four-day old larvae were fed daily with 160g (70% relative humidity) of diets for 6 days and harvested 3 days later. Although their growth and total biomass were significantly lower than the standard diet, larvae fed on hydrolyzed digestate were almost two times larger than the larvae fed on crude digestate. Furthermore, the content of organic matter, lipids and minerals in the diets and frass were analyzed. Finally, the feasibility of applying BSF treatment for digestate valorization is discussed. According to this study, enzyme-treated digestate does not allow efficient larval growth compared to the standard diet. The development of a more effective method of pretreatment is required for BSF larvae to become an eco-friendly solution for digestate valorization.

A Study and Modeling of Bifidobacterium and Bacillus Coculture Continuous Fermentation under Distal Intestine Simulated Conditions.

The diversity and the stability of the microbial community are associated with microecological interactions between its members. Antagonism is one type of interaction, which particularly determines the benefits that probiotics bring to host health by suppressing opportunistic pathogens and microbial contaminants in food. Mathematical models allow for quantitatively predicting intrapopulation relationships. The aim of this study was to create predictive models for bacterial contamination outcomes depending on the probiotic antagonism and prebiotic concentration. This should allow an improvement in the screening of synbiotic composition for preventing gut microbial infections. The functional model (fermentation) was based on a three-stage continuous system, and the distal colon section (N2, pH 6.8, flow rate 0.04 h–1) was simulated. The strains Bifidobacterium adolescentis ATCC 15703 and Bacillus cereus ATCC 9634 were chosen as the model probiotic and pathogen. Oligofructose Orafti P95 (OF) was used as the prebiotic at concentrations of 2, 5, 7, 10, 12, and 15 g/L of the medium. In the first stage, the system was inoculated with Bifidobacterium, and a dynamic equilibrium (Bifidobacterium count, lactic, and acetic acids) was achieved. Then, the system was contaminated with a 3-day Bacillus suspension (spores). The microbial count, as well as the concentration of acids and residual carbohydrates, was measured. A Bacillus monoculture was studied as a control. The stationary count of Bacillus in monoculture was markedly higher. An increase (up to 8 h) in the lag phase was observed for higher prebiotic concentrations. The specific growth rate in the exponential phase varied at different OF concentrations. Thus, the OF concentration influenced two key events of bacterial infection, which together determine when the maximal pathogen count will be reached. The mathematical models were developed, and their accuracies were acceptable for Bifidobacterium (relative errors ranging from 1.00% to 2.58%) and Bacillus (relative errors ranging from 0.74% to 2.78%) count prediction.

Chlorella pyrenoidosa Polysaccharides as a Prebiotic to Modulate Gut Microbiota: Physicochemical Properties and Fermentation Characteristics In Vitro.

This study was conducted to investigate the prebiotic potential of Chlorella pyrenoidosa polysaccharides to provide useful information for developing C. pyrenoidosa as a green healthy food. C. pyrenoidosa polysaccharides were prepared and their physicochemical characteristics were determined. The digestibility and fermentation characteristics of C. pyrenoidosa polysaccharides were evaluated using in vitro models. The results revealed that C. pyrenoidosa polysaccharides were composed of five non-starch polysaccharide fractions with monosaccharide compositions of Man, Rib, Rha, GlcA, Glc, Gal, Xyl and Ara. C. pyrenoidosa polysaccharides could not be degraded under saliva and the gastrointestinal conditions. However, the molecular weight and contents of residual carbohydrates and reducing sugars of C. pyrenoidosa polysaccharides were significantly reduced after fecal fermentation at a moderate speed. Notably, C. pyrenoidosa polysaccharides could remarkably modulate gut microbiota, including the promotion of beneficial bacteria, inhibition of growth of harmful bacteria, and reduction of the ratio of Firmicutes to Bacteroidetes. Intriguingly, C. pyrenoidosa polysaccharides can promote growth of Parabacteroides distasonis and increase short-chain fatty acid contents, thereby probably contributing to the promotion of intestinal health and prevention of diseases. Thus, these results suggested that C. pyrenoidosa polysaccharides had prebiotic functions with different fermentation characteristics compared with conventional prebiotics such as fructooligosaccharide, and they may be a new prebiotic for improving human health.

Distinctive Traits of Four Apulian Traditional Agri-Food Product (TAP) Cheeses Manufactured at the Same Dairy Plant.

This study aimed to highlight the distinctive features of four Traditional Agri-food Products (TAP), namely, Caprino, Pecorino, Vaccino, and Cacioricotta cheeses produced at the same dairy plant to reveal any possible relationships between their microbiological and biochemical characteristics. Two distinct natural whey starter (NWS) cultures were used during Caprino and Vaccino cheesemaking, whereas no starter was used for the other cheeses. Cacioricotta retained the highest concentrations of salt and residual carbohydrates. Lactic acid bacteria dominated the microbiota of the cheeses. Furthermore, staphylococci represented an additional dominant microbial population in Cacioricotta. Although culture-dependent analysis showed that the use of NWS cultures only slightly affected the microbial community of cheeses, 16S metagenetic analysis showed that Lactobacillus helveticus dominated both the NWS cultures and the corresponding Caprino and Vaccino cheeses. This analysis indicated that Staphylococcus equorum and Streptococcus thermophilus dominated Cacioricotta and Pecorino cheeses, respectively. The highest peptidase activities were found in either Caprino or Vaccino. Enzymes involved in the catabolism of free amino acids and esterase showed the highest activity in Pecorino cheese. Each cheese showed a distinct profile of volatile organic compounds, with Pecorino being the richest cheese in carboxylic acids, ketones, and esters, related to lipolysis. The results of this study contribute to valorizing and safeguarding these TAP cheeses, sustaining local farming.

The Action of Recombinant Human Lysosomal α-Glucosidase (rhGAA) on Human Liver Glycogen: Pathway to Complete Degradation

Glycogen is present in all tissues, but it is primarily stored in the liver and in muscle. As a branched chain carbohydrate, it is broken down by phosphorylase and debrancher enzymes, which are cytoplasmic. It is also degraded by a lysosomal α-glucosidase (GAA) also known as acid α-glucosidase and lysosomal acid α-glucosidase. The deficiency of GAA in patients is known as Pompe disease, and the phenotypes as infantile, juvenile and later onset forms. Pompe disease is treated by enzyme replacement therapy (ERT) with a recombinant form of rhGAA. Following ERT in Pompe mice and human patients there is residual carbohydrate material present in the cytoplasm of cells. The goal of this work is to improve ERT and attempt to identify and treat the residual cytoplasmic carbohydrate. Initial experiments were to determine if rhGAA can completely degrade glycogen. The enzyme cannot completely degrade glycogen. There is a residual glycosylated protein as well as a soluble glycosylated protein, which is a terminal degradation product of glycogen and as such serves as a biomarker for lysosomal glycogen degradation. The glycosylated protein has a very unusual carbohydrate composition for a glycosylated protein: m-inositol, s-inositol and sorbitol as the major carbohydrates, as well as mannitol, mannose, glucose and galactose. This work describes the residual material which likely contains the same protein as the soluble glycosylated protein. The biomarker is present in serum of control and Pompe patients on ERT, but it is not present in the serum of Pompe mice not on ERT. Pompe mice not on ERT have another glycosylated protein in their serum which may be a biomarker for Pompe disease. This protein has multiple glycosylation sites, each with different carbohydrate components. These glycosylated proteins as well as the complexity of glycogen structure are discussed, as well as future directions to try to improve the outcome of ERT for Pompe patients by being able to monitor the efficacy of ERT in the short term and possibly to adjust the timing and dose of enzyme infusions.

Comparison of organic acid-based organosolv lignins extracted from the residues of five annual crops

Organosolv lignins were extracted from corn stover, wheat, rice straw, reed straw, and sugarcane bagasse using a mixture of acetic and formic acids, at relatively low temperature and atmospheric pressure. Lignin content, residual carbohydrates, ash levels, proteins, and molecular weights were determined in each extracted lignin. The lignin content of all samples was relatively high, confirming the performance of the pretreatment process. The low molecular weights were in a narrow range, in accordance with the organosolv lignin molar masses. However, some differences between studied lignins were highlighted, in particular in rice straw lignin, which contained the highest silica, calcium, and nitrogen contents. Nuclear magnetic resonance spectroscopies (31P and semi-quantitative Heteronuclear Single Quantum Correlation) underlined the structural similarities and differences between these organosolv lignins. Corn stover and sugarcane bagasse lignins were rich in non-methoxylated (H-Unit) or mono-methoxylated (G-Unit) phenolic units, making them the best promising candidates for production of phenolic resins. Wheat straw lignin was richer in aliphatic OH than in phenolic OH. This is an advantage for use as polyol substitute in polyurethane synthesis. Reed straw lignin was less specific, with a balanced content of OH groups. However, it contained a high concentration of β-O-4 linkages, which is favorable for depolymerization.

Chemical reactivity and sulfo-functionalization response of enzymatically produced lignin

This study focuses on the physicochemical characterization of lignin produced via enzymatic hydrolysis of hardwood chips. Enzymatically produced lignin (HL) was water-insoluble particles that contained carbohydrates that were chemically bound to lignin. The X-ray photoelectron spectroscopy (XPS), 1H-NMR, 13C-NMR, 31P NMR and two-dimensional 1H-13C HSQC, 1H-13C HSQC-TOCSY, 1H-13C HMBC NMR analyses confirmed that the HL samples with the lower internal ether linkages had fewer β-O-4 aryl ether and lignin-carbohydrate (LCC) bonds but more phenolic hydroxyl and carboxylate groups. Moreover, the samples with the lower sugar content were smaller and more porous. The chemical reactivity analysis of HL samples in various sulfo-functionalization reactions (sulfonation S, sulfomethylation SM, and sulfoethylation SE) revealed a direct correlation between the degree of substitution (DS) and phenolic guaiacyl (G) and the condensed hydroxyl group of HL. Also, the carbohydrate content and particle size of HL were inversely related to the degree of substitution of sulfo-functionalization of HL. The SM- and S- modified HL samples with adequate water solubility (9−10 g/L), charge density (≥1.9 mmol/g), and small particle size (5 μm) were shown to be effective stabilizers for clay suspensions via reducing the instability index (TSI∼10) and settling velocity (−4 %/h) of clay particles in the suspension. The results obtained in this study shed light on the significant role of residual carbohydrates and internal ether linkages of HL on the physicochemical properties and sulfo-functionalization of HL.

Correlating bacterial and archaeal community with efficiency of a coking wastewater treatment plant employing anaerobic-anoxic-oxic process in coal industry

Coking wastewater (CWW) contains various complex pollutants, and biological treatment processes are frequently applied in the coking wastewater treatment plants (CWWTPs). The present work is to evaluate the contaminants removal of a full-scale CWWTP with an anaerobic-anoxic-oxic process (A/A/O), to reveal function of bacterial and archaeal community involved in different bioreactors, and to clarify the relationship between the performance and microbial community. Illumina Miseq sequencing of bacteria showed that β-proteobacteria dominated in three bioreactors with relative abundance of 60.2%~81.7%. 75.2% of sequences were assigned to Petrobacter in the bioreactor A1, while Thiobacillus dominated in A2 and O with relative abundance of 31.8% and 38.7%, respectively. Illumina Miseq sequencing of archaea revealed a high diversity of methanogens existed in A1 and A2 activated sludge. Moreover, Halostagnicola was the dominant archaea in A1 and A2 activated sludge with relative abundance of 41.8% and 66.5%, respectively. Function predicted analysis explored that function of bacteria was similar to that of archaea but the relative abundance differed from each other. A putative biodegradation model of CWW treatment in A/A/O process indicated that A1 and A2 activated sludge mainly reduced carbohydrate, protein, TN, phenol and cyanide, as well as methane production. Bacteria in the bioreactor O were responsible for aerobic biotransformation of residual carbohydrates, refractory organics and nitrification. The redundancy analysis (RDA) further revealed that removal of COD, TN, and NO3−-N, phenol and cyanides were highly correlated with some anaerobic bacteria and archaea, whereas the transformation of NH4+-N was positively correlated with some aerobic bacteria.

Deconstruction of banana peel for carbohydrate fractionation.

The deconstruction of banana peel for carbohydrate recovery was performed by sequential treatment (acid, alkaline, and enzymatic). The pretreatment with citric acid promoted the extraction of pectin, resulting in a yield of 8%. In addition, xylose and XOS, 348.5 and 17.3mg/g xylan, respectively, were also quantified in acidic liquor as a result of partial depolymerization of hemicellulose. The spent solid was pretreated with alkaline solution (NaOH or KOH) for delignification and release of residual carbohydrates from the hemicellulose. The yields of xylose and arabinose (225.2 and 174.0mg/g hemicellulose) were approximately 40% higher in the pretreatment with KOH, while pretreatment with NaOH promoted higher delignification (67%), XOS yield (32.6mg/g xylan), and preservation of cellulosic fraction. Finally, the spent alkaline solid, rich in cellulose (76%), was treated enzymatically to release glucose, reaching the final concentration of 28.2g/L. The mass balance showed that through sequential treatment, 9.9g of xylose, 0.5g of XOS, and 8.2g of glucose were obtained from 100g of raw banana peels, representing 65.8% and 46.5% conversion of hemicellulose and cellulose, respectively. The study of the fractionation of carbohydrates in banana peel proved to be a useful tool for valorization, mainly of the hemicellulose fraction for the production of XOS and xylose with high value applications in the food industry.