Machine learning prediction of novel pectinolytic enzymes in Aspergillus niger through integrating heterogeneous (post-) genomics data

Pectinolytic enzymes are a variety of enzymes involved in breaking down pectin, a complex and abundant plant cell-wall polysaccharide. In nature, pectinolytic enzymes play an essential role in allowing bacteria and fungi to depolymerize and utilize pectin. In addition, pectinases have been widely applied in various industries, such as the food, wine, textile, paper and pulp industries. Due to their important biological function and increasing industrial potential, discovery of novel pectinolytic enzymes has received global interest. However, traditional enzyme characterization relies heavily on biochemical experiments, which are time consuming, laborious and expensive. To accelerate identification of novel pectinolytic enzymes, an automatic approach is needed. We developed a machine learning (ML) approach for predicting pectinases in the industrial workhorse fungus, Aspergillus niger. The prediction integrated a diverse range of features, including evolutionary profile, gene expression, transcriptional regulation and biochemical characteristics. Results on both the training and the independent testing dataset showed that our method achieved over 90 % accuracy, and recalled over 60 % of pectinolytic genes. Application of the ML model on the A. niger genome led to the identification of 83 pectinases, covering both previously described pectinases and novel pectinases that do not belong to any known pectinolytic enzyme family. Our study demonstrated the tremendous potential of ML in discovery of new industrial enzymes through integrating heterogeneous (post-) genomimcs data.

Dynamic generation of aqueous foams and fiber foams in a mixing tank

Mixing tanks are employed in paper and pulp industries to generate aqueous foams and fiber foams. The aim of the present study was to investigate the effect of impeller geometry on dynamic foam generation in a 60 L mixing tank. Three impeller geometries including two radial—Rushton turbine (RT), Bakker turbine (BT6), one axial high solidity pitched blade turbine (HSPBT), and four dual impeller combinations were investigated. Compressed air, water and sodium dodecyl sulphate were used as gas phase, liquid phase and surfactant, respectively, to generate aqueous foam. 1% mass consistency softwood fiber was used to generate fiber foam. The change in aqueous foam density for any given impeller was limited to ± 40 kg/m3 indicating foam density was dictated by impeller type rather than power input. Single impellers generated bubbly liquids whereas dual impellers generated low-density aqueous foams. Besides, stable foam was produced even at low power input compared to single impellers due to increase in impeller swept volume and blade contact area. Addition of fibers increased the foam density by ~ 100–150 kg/m3 and reduced the half-life time by almost threefold for all impellers due to lower air content and higher bubble size. Placement of high shear impeller (BT6) at bottom and down-pumping axial impeller (HSPBT) on top generated fine bubbles.

The effect of protic solvents in the conversion of lignin from Earleaf Acacia tree

Lignin is one of main components of lignocellulosic along with cellulose and hemicellulose. It is a by-product of the paper and pulp industry, and has aromatic backbones making them an ideal renewable feedstock of aromatic compounds for a range of applications. Catalytic conversion of lignin from Earleaf Acacia tree was performed using high pressure/temperature reactor with Ru/C catalyst and protic solvents. The results showed that the conversion of lignin depends on the solvent polarity of protic solvents, and Ru/C catalyst enhanced the lignin conversion. Phenolic compounds are the main components of lignin conversion. Those compounds can be applied as a basement for bulk chemical and fuels.

Membrane Filtration Opportunities for the Treatment of Black Liquor in the Paper and Pulp Industry

Black liquor is a highly alkaline liquid by-product of the kraft pulping process, rich in organic molecules (hemicelluloses, lignin, and organic acids) and inorganic pulping chemicals such as sodium salts and sulphur-containing compounds. The release of this wastewater without further treatment could have serious environmental and financial implications. Therefore, a costly treatment process is used nowadays. Nanofiltration has been studied in the last few years as a promising alternative to recycle the cooking chemicals required for the separation of lignin and cellulose, but the development of pH-stable membranes with the potential to operate at industrial scales is fundamental in order to make this possible. In this study, the filtration performance of two in-house made membranes is evaluated and compared with a commercial NF membrane to determine the viability of their use for the treatment of black liquor. For this purpose, filtration experiments with simulated black liquor were performed. We identified that Membrane A has the higher potential for this application due to its competitive permeate flux (ca. 24 L m−2 h−1 at a trans-membrane pressure of 21.5 bar), and high rejection of organic components and salts from the cooking liquor (on average, 92.50% for the TOC, 84.10% for the CO32−, 88.70% for the sulphates, 73.21% for the Na+, and 99.99% for the Mg2+).

Peroxidase, an Example of Enzymes with Numerous Applications

The enzyme peroxidase is a heme or iron-porphyrin protein that belongs to a large family of enzymes called the oxidoreductases. Their function mainly is to oxidize molecules at the expense of hydrogen peroxide. They are widely distributed in living organisms, and usually show dramatic colour-product formation as a result of their catalytic effect. They generally catalyse many oxygen transfer reactions involving hydrogen peroxide or anyone of the many other peroxides as electron acceptors and substrates. This ability of reducing peroxides at the expense of electron donating substrates is what marks peroxidases as ubiquitous and very important enzymes with many biotechnological applications. Not surprisingly therefore peroxidases play many important roles in different areas of biotechnology. Among others, these include such diverse areas as bioenergy, bioremediation, dye decolorization, humic acid degradation, paper and pulp and textile industries among many others. An important reason for this ability is the different areas from which peroxidases could be sourced as the function of many peroxidases show variations according to its source. This is a character that differentiates peroxidases from many other biological catalysts. Among the many different types of peroxidases are the heme peroxidases which mainly come from plants and fungi and include among others lignin peroxidases, manganese peroxidases and versatile peroxidases. Some important types of peroxidases from humans and animals are glutathione peroxidase, thyroid peroxidase, lactoperoxidase, salivary peroxidase and thyroid peroxidase.

Agricultural Residues as an Alternative Source of Fibre for the Production of Paper in Kenya-A Review

The pulp and paper industry is primarily dependent on fibrous wood for pulp and paper production. However, this over-dependence on fibrous wood poses serious environmental challenges such as the diminishing of the fibrous wood stocks, deforestation, emission of greenhouse gases, and global warming. Therefore, to mitigate these environmental challenges associated with its utilization for paper and pulp production, other sustainable raw material sources can also be considered for the production of paper and pulp. There are enormous benefits associated with the utilization of non-wood fibres as an alternative and sustainable raw materials source for the production of paper and pulp. These benefits have in the recent past prompted millers in China, India, Brazil, and the USA to consider the utilization of non-wood fibres in paper and pulp production. In Kenya, the pulp and paper industry is very much dependent on fibrous wood for production and the industry is yet to fully embrace the utilization of nonwood fibres for paper and pulp production. Further, the dependence on fibrous wood has contributed significantly to the decline of paper pulp and paper production, deforestation, and rise in paper importations due to insufficient raw material supplies. The importation of paper and pulp products has further led to the collapse of the paper industry in Kenya. The sector stands a chance of revival and vibrancy through the utilization of the abundant agricultural residues and feedstocks lying in the agricultural fields across the country. Similar experiences elsewhere have proved that the abundance of agricultural waste can be utilized for the production of paper and pulp due to their excellent fibre content for specialty papers, and easy pulpability. The agricultural residues are therefore considered a quintessential alternative and sustainable source of raw materials for the pulp and paper industry. Moreover, their utilization will mitigate environmental impacts such as deforestation, climate change, and pollution .

Bioremoval capacity of phenol by some selected endophytic fungi isolated from Hibiscus sabdariffa and batch biodegradation of phenol in paper and pulp effluents

Background and Objectives: The use of endophytic fungi for management of phenol residue in paper and pulp industries has been shown as cost-effective and eco-friendly approach. In this study, isolation of endophytic fungi from roots, stems, and leaves of Hibiscus sabdariffa was conducted. Additionally, the isolated fungi were examined for their ability to degrade phenol and its derivatives in paper and pulp industrial samples, using different growth conditions. Materials and Methods: Out of 35 isolated endophyitc fungi, 31 were examined for their phenol biodegradation capacity using Czapek Dox broth medium containing Catechol and Resorcinol as a sole carbon source at final concentrations of 0.4, 0.6 and 0.8%. Results: A total of 35 fungal species belonging to 18 fungal genera were isolated and identified from different parts of H. sabdariffa plants. All strains have the capability for degrading phenol and their derivatives with variable extents. The optimum condition of degrading phenol in paper and pulp effluent samples by Fusarium poae11r7 were at pH 3-5, temperature at 28-35°C, good agitation speed at no agitation and 100 rpm. Conclusion: All endophytic fungal species can utilize phenol and its derivatives as a carbon source and be the potential to degrade phenol in industrial contaminants.

New approach for selecting a suitable recycling collection program for recovered paper and pulp recyclables using AHP-TOPSIS techniques

In the past decade, the use of multiple-criteria decision analysis technology has dramatically increased in solving complex real-world problems in solid waste management. Likewise, many municipalities have paid attention to finding feasible solutions for disposal and recycling of solid waste due to the increase in waste generation rates worldwide. Therefore, policy-makers must determine which recycling program to be implemented among various recycling program options. In this paper, a new approach to select a recycling program for recovered paper and pulp recyclables was proposed using analytic hierarchy process–Technique for Order Preference by Similarity to Ideal Solution (AHP-TOPSIS) techniques. A set of essential parameters of the decision-making system were identified, and a numerical case to illustrate the procedure was conducted. Our findings show very encouraging results to use a combined model between AHP and TOPSIS to select a suitable recycling program for different recovered recyclable materials.