![Structure of the wood cell wall. a Structure of a wood cell wall made up of the middle lamella, primary cell wall, and the secondary cell wall (Sticklen 2008). b Structure of the secondary cell wall containing cellulose fibers bound to lignin and hemicellulose (Sticklen 2008)(Reprinted with permission from Macmillan Publishers Ltd: [Nature Reviews] (Sticklen 2008))](https://www.researchgate.net/profile/Amy-Grunden/publication/272835310/figure/fig1/AS:314894667796480@1452088147987/Structure-of-the-wood-cell-wall-a-Structure-of-a-wood-cell-wall-made-up-of-the-middle_Q320.jpg)
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Bacterial biodegradation and bioconversion of industrial lignocellulosic streams
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Lignocellulose is a term for plant materials that are composed of matrices of cellulose, hemicellulose, and lignin. Lignocellulose is a renewable feedstock for many industries. Lignocellulosic materials are used for the production of paper, fuels, and chemicals. Typically, industry focuses on transforming the polysaccharides present in lignocellulose into products resulting in the incomplete use of this resource. The materials that are not completely used make up the underutilized streams of materials that contain cellulose, hemicellulose, and lignin. These underutilized streams have potential for conversion into valuable products. Treatment of these lignocellulosic streams with bacteria, which specifically degrade lignocellulose through the action of enzymes, offers a low-energy and low-cost method for biodegradation and bioconversion. This review describes lignocellulosic streams and summarizes different aspects of biological treatments including the bacteria isolated from lignocellulose-containing environments and enzymes which may be used for bioconversion. The chemicals produced during bioconversion can be used for a variety of products including adhesives, plastics, resins, food additives, and petrochemical replacements.
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... Brewer's spent grains, chemical pulps (e.g., waste sulfite liquor from pulp), and waste papers from paper mills. [22,[45][46][47][48] Food wastes The kitchen remains, such as vegetable peels and fruit waste. [49] Agro-wastes Animal manure (e.g., solid cattle, cow, and pig manure). ...
... Lignocellulose, considered second-generation feedstock, is a promising raw material for producing a number of value-added products. Recently, the focus has been on efficiently converting lignocellulose into value-added products, as polysaccharides, such as cellulose and hemicellulose, in lignocellulose bio-transformed into new products may be underutilized, resulting in the incomplete use of lignocellulose [46]. Bioconversion strategies that have been intensively used to consume these polysaccharides completely include biochemical and thermochemical approaches [6]. ...
Lignocellulose consists of cellulose, hemicellulose, and lignin and is a sustainable feedstock for a biorefinery to generate marketable biomaterials like biofuels and platform chemicals. Enormous tons of lignocellulose are obtained from agricultural waste, but a few tons are utilized due to a lack of awareness of the biotechnological importance of lignocellulose. Underutilizing lignocellulose could also be linked to the incomplete use of cellulose and hemicellulose in biotransformation into new products. Utilizing lignocellulose in producing value-added products alleviates agricultural waste disposal management challenges. It also reduces the emission of toxic substances into the environment, which promotes a sustainable development goal and contributes to circular economy development and economic growth. This review broadly focused on lignocellulose in the production of high-value products. The aspects that were discussed included: (i) sources of lignocellulosic biomass; (ii) conversion of lignocellulosic biomass into value-added products; and (iii) various bio-based products obtained from lignocellulose. Additionally, several challenges in upcycling lignocellulose and alleviation strategies were discussed. This review also suggested prospects using lignocellulose to replace polystyrene packaging with lignin-based packaging products, the production of crafts and interior decorations using lignin, nanolignin in producing environmental biosensors and biomimetic sensors, and processing cellulose and hemicellulose with the addition of nutritional supplements to meet dietary requirements in animal feeding.
... Biofuels and biobased products converted from lignocellulose biomass are expected to reduce global dependence on fossil fuels and greenhouse gas emissions (Qing et al. 2016). Lignocellulose is one of the most abundant renewable resources, with more than 40 million tons of lignocellulose feedstock produced globally each year, accounting for 50 percent of the global biomass, including agroforestry waste, paper waste, energy crops, etc., most of which go unused and discarded (Sanderson 2011;Mathews et al. 2015;Yin et al. 2018;Kalsoom et al. 2019). Bamboo is a perennial herb, rich in cellulose, hemicellulose, and lignin. ...
This study focuses on the pretreatment and characterization of natural fibers from the bamboo shoot shell (BSS) of Phyllostachys heterocycla to determine their suitability as biorefining materials. The discarded bamboo shoot shell was used as a source of fibers, which were analyzed for their physical, chemical, and microstructure properties. Fourier transform infrared spectroscopy, X-ray diffraction spectra, and scanning electron microscopy confirmed that a mixture of sodium hydroxide immersion plus high-pressure steam treatment allowed the cellulose structure to be disrupted, providing more adsorption sites for cellulases. Gas chromatography mass spectrometry (GC-MS) also showed that the pretreatment exposed the internal structure of the fibers and that high-mass silicon compounds were present in the eluted solution. After adding the cellulase produced by Trichoderma viride and Aspergillus niger, the reducing sugar yield was increased by 268% and 251%, compared to unpretreated BSS fibers. This strategy may apply to many industries, especially biorefining and lignocellulose biotransformation technology.
... Biomass has received widespread attention in recent years for its usability, low cost and renewable properties [1], with biofuels and biobased products converted from lignocellulose biomass expected to reduce global dependence on fossil fuels and greenhouse gas emissions [2]. Lignocellulose is one of the most abundant biomass in nature, with more than 40 million tons of Lignocellulose feedstock produced globally each year, accounting for 50 percent of the global biomass, including agroforestry waste, paper waste, energy crops, etc., most of which go unused and discarded [3][4][5][6]. Bamboo is a perennial herb, rich in cellulose, hemicellulose and lignin lignocellulose. It is estimated that the annual production of bamboo shoot shells (BSS) in China exceeds about 20 million tons [7][8][9]. ...
This study focuses on the pretreatment and characterization of natural fibers from the bamboo shoot shell(BSS) of Phyllostachys hterocycla , a species of bamboo, to determine their suitability as biorefining materials. The discarded bamboo shoot shell was used for fiber extraction, and the resulting fibers were analyzed for their physical, chemical, and microstructure properties.The Fourier transform infrared spectroscopy,X-ray diffraction spectra and scanning electron microscopy also confirmed that a mixture of sodium hydroxide immersion plus high-pressure steam treatment allowed the cellulose structure to be disrupted, providing more adsorption sites for cellulases.Gas Chromatography Mass Spectrometry (GC-MS) also showed that the internal structure of the fibers was eluted.The cellulaseproduced by ( Trichoderma green and Aspergillus niger ) reducing sugar yields produced also increased by 267.69% and 250.57%, compared to unpretreated BSS fibers.This strategy may apply to many industries, especially biorefining and lignocellulose biotransformation technology.
... These properties facilitate greater access and utilization of substrates even under drought conditions (de Vries et al., 2018). Some bacterial phyla are more tolerant to harsh conditions than fungi (Mathews et al., 2015). For instance, Bacillus subtilis, a spore-forming bacterium, enters a metabolically dormant state to cope with harsh environments (Earl et al., 2008). ...
Microbial interactions in soil are hidden, as they occur stealthily in a ‘dark box’. This greatly limits our understanding of microbial functions. Here, soil microorganisms were classified into three broad functional groups, namely miners, scavengers and carriers, to disentangle the intricate microbial labor division and interactions for nutrient acquisition. Miners, such as saprotrophic microorganisms, N2-fixing and phosphate-solubilizing bacteria, and ectomycorrhizal (ECM) fungi, first decompose or mobilize not directly bioavailable organic or inorganic substances through hydrolysis, oxidation and/or mineralization. Scavengers, arbuscular mycorrhizal (AM) fungi as a typical example, explore and efficiently take up nutrients with assistance of host plants, but cannot access nutrients stored in organic matter or minerals. Carriers with filamentous growth such as ECM, AM and saprotrophic fungi transport nutrients and unicellular bacteria to new locations exploiting a large soil volume for nutrients. These three groups build ‘division of labor’ and interaction networks, which reduce the metabolic burden, increase substrate utilization efficiency, and ultimately increase nutrient acquisition in the rhizosphere, detritusphere, and bulk soil. Notably, such grouping of soil microorganisms based on functions is flexible, and a particular microorganism can be versatile. Flexibility in ecological functions and consequence of interactions is necessary to respond to shifting soil nutrient content, organic matter availability, and edaphic conditions. Nevertheless, such broad grouping is conducive to condense functional diversity and allows a better understanding of mutualistic interactions among microbial groups, contributing to hotspot formation and disappearance, nutrient mobilization and delivery to roots. A combination of laboratory studies on pairwise interactions, experiments using synthetic microbial communities with network analysis and imaging techniques is essential to unravel tangled webs of microbial associations. In summary, the interactions among microbial groups classified based on their interconnected ecological processes as miners, scavengers and carriers are important to uncover the true functional roles of microorganisms in ecosystems.
Coffee is a critical agricultural commodity and is used to produce premium beverages enjoyed by people worldwide. The microbiome of coffee beans has proven to be an essential tool that improves the flavor profile of coffee by creating aromatic flavor compounds through natural fermentation. Study of the microbial diversity of coffee beans has contributed to methods for rapid fermentation, as well as creating better quality of the final product. This study investigated the natural microbial consortium during wet process fermentation of coffee onsite in Thailand. Our study found 64 genera of bacteria and 59 genera of yeast/ fungi present during the fermentation process. A correlation between microbial diversity and biochemical characteristics including flavor, aroma and metabolic attributes was investigated.
The present work focuses on isolating, screening and biochemical characetization of laccase producing bacteria.Lignin is the most abundant aromatic polymer found as a major component of lignocellulose in plant cell walls and is extremely resistant to chemical and biochemical breakdown. Research on lignin biodegradation has accelerated greatly during the past 20 years, mainly because of the substantial potential applications of bio-ligninolytic systems in pulping, bleaching, converting lignins to useful products and treating of agricultural wastes using bacteria. Isolation and identification of environmental friendly bacteria for lignin degradation becomes an essential, because all the previous researches concentrated on using fungal treatments. However, bacteria seem to play a leading role in decomposing lignin because wood degrading bacteria have a wider tolerance of temperature, pH and oxygen limitations than fungi. Therefore, in this study soils were collected from wood industry and used for isolation of lignin degrading bacteria. Four bacterial strains were isolated by screening procedure based on their oxidative activity on ABTS (2,2'-azinobis(3-ethylbenzthiazoline-6-sulfonate) and by a indicator Bromo phenol blue and later by the biochemical characterization strains were identified as Enterobacter, E.coli and two strains of Serritia.
An ideal renewable resource is one that can be replenished over a relatively short timescale or is essentially limitless in supply. Improved resource utilisation can positively influence the profits of industry as well as enable new companies to start up, produce new growth and expand innovation opportunities by moving towards the ultimate sustainability goal of a zero-waste circular economy. Green chemistry emerged in the 1990s as a movement dedicated to the development of more environmentally benign alternatives to hazardous and wasteful chemical processes as a result of the increased awareness in industry of the costs of waste and of government regulations requiring cleaner chemical manufacturing. Three different types of biorefinery have been described in the literature: Phase I biorefinery (single feedstock, single process and single major product), Phase II biorefinery (single feedstock, multiple processes and multiple major products) and Phase III biorefinery (multiple feedstocks, multiple processes and multiple major products).
The lignin present in plant tissues is referred to as native or natural lignin. During the industrial delignification of lignocellulosic materials such as wood, lignin undergoes significant structural changes; so the lignins obtained under industrial conditions, the so-called technical lignins, are not identical with the native ones in their structures.
Cellulolytic microorganisms play an important role in the biosphere by recycling cellulose, the most abundant carbohydrate produced by plants. Cellulose is a simple polymer, but it forms insoluble, crystalline microfibrils, which are highly resistant to enzymatic hydrolysis. All organisms known to degrade cellulose efficiently produce a battery of enzymes with different specificities, which act together in synergism. The study of cellulolytic enzymes at the molecular level has revealed some of the features that contribute to their activity. In spite of a considerable diversity, sequence comparisons show that the catalytic cores of cellulases belong to a restricted number of families. Within each family, available data suggest that the various enzymes share a common folding pattern, the same catalytic residues, and the same reaction mechanism, i.e. either single substitution with inversion of configuration or double substitution resulting in retention of the β-configuration at the anomeric carbon. An increasing number of three-dimensional structures is becoming available for cellulases and xylanases belonging to different families, which will provide paradigms for molecular modeling of related enzymes. In addition to catalytic domains, many cellulolytic enzymes contain domains not involved in catalysis, but participating in substrate binding, multi-enzyme complex formation, or possibly attachment to the cell surface. Presumably, these domains assist in the degradation of crystalline cellulose by preventing the enzymes from being washed off from the surface of the substrate, by focusing hydrolysis on restricted areas in which the substrate is synergistically destabilized by multiple cutting events, and by facilitating recovery of the soluble degradation products by the cellulolytic organism. In most cellulolytic organisms, cellulase synthesis is repressed in the presence of easily metabolized, soluble carbon sources and induced in the presence of cellulose. Induction of cellulases appears to be effected by soluble products generated from cellulose by cellulolytic enzymes synthesized constitutively at a low level. These products are presumably converted into true inducers by transglycosylation reactions. Several applications of cellulases or hemicellulases are being developed for textile, food, and paper pulp processing. These applications are based on the modification of cellulose and hemicellulose by partial hydrolysis. Total hydrolysis of cellulose into glucose, which could be fermented into ethanol, isopropanol or butanol, is not yet economically feasible. However, the need to reduce emissions of greenhouse gases provides an added incentive for the development of processes generating fuels from cellulose, a major renewable carbon source.