ReviewLignocellulosic crop residue composting by cellulolytic nitrogen-fixing bacteria: A novel tool for environmental sustainability
Graphical abstract
Introduction
Lignocellulosic crop residues (LCCRs) are produced in large quantities worldwide and are effective carbon-rich materials for the production of soil conditioners. However, in many countries, LCCRs are frequently burnt after harvest to facilitate land preparation, which causes massive environmental pollution and loss of plant nutrients (Kim Oanh et al., 2018). The incorporation of LCCRs into soil reduces the amount of plant-available nitrogen as the microbial biomass which develops during decomposition of the lignocellulosic plant material needs more nitrogen than the amount that is provided by the substrate and the final breakdown products of LCCRs tend to be phytotoxic (Ocio et al., 1991).
In most developing countries, LCCRs are commonly used as a part of feeding ingredients for the ruminants. However, they have a low nutritional value due to their poor digestibility, nitrogen deficiency and high levels of anti-nutritional components (lignin and silica) (Van Soest, 2006; Aquino et al., 2020). The most commonly used practice to increase the nutritive value of LCCRs is treatment of the LCCRs with chemicals such as urea, ammonia or sodium hydroxide (Aquino et al., 2020), with sodium hydroxide being recommended by the Food and Agriculture Organization (FAO) (2008). However, these chemicals are expensive and hazardous, and can cause a variety of environmental effects such as sodium contamination of the soil coupled with air pollution and water pollution (Liu et al., 1999).
The search for cost-effective, fast, and sustainable alternative processes for the better management of LCCRs to solve environmental issues is therefore of paramount importance and one of the greatest challenges in agriculture. Aerobic composting has been extensively studied and the results have shown that it can be an eco-sustainable green approach for LCCR treatment and agricultural development. The bulk of research on aerobic composting can be found on the Web of Science Core Collection database (Fig. 1). This natural bioprocess enhances the long-term sustainability of agriculture by converting agriculture wastes into nutrient-rich compost (Kausar et al., 2016). Furthermore, the compost can be applied as a soil conditioner, organic fertilizer, and plant growth stimulator, thus reducing dependence on chemical fertilizers for crop production. The results of recent research on compost application have shown the positive effects of compost use on the environmental resilience and climate adaptation, that has been observed as improved plant growth, stabilization of soils, and reduced air pollution and water pollution (Lim et al., 2016; Xia Guo et al., 2019). The compost should be highly mature and stable in order to be used safely in agriculture without adverse effects on plants. Immature compost may produce phytotoxic compounds that may disrupt seed germination and plant growth (Makan, 2015).
The ordinary composting of LCCRs is intensely dilatory due to the low nitrogen content of the carbon-rich LCCRs. This limitation can be overcome by using microorganisms with both nitrogen-fixing and cellulose-degrading properties (Yu et al., 2017). Numerous nitrogen-fixing bacteria such as Azomonas agilis, Stenotrophomonas spp., Bacillus spp., Streptomyces spp., Pseudomonas spp., Paenibacillus azotofixans, and Gluconacetobacter spp. (Table 2) produce lignocellulolytic enzymes (Leschine et al., 1988; Kyaw et al., 2018; Latt et al., 2018). Furthermore, the inoculation of two cellulolytic nitrogen-fixing Bacillus strains in composting of rice straw has been shown to reduce the composting time by 40%–43% and increased the levels of total nitrogen, phosphorus, and potassium in the compost (Abdel-Rahman et al., 2016). Additionally, the application of different bacterial agents with both cellulolytic and nitrogen-fixing properties has been shown to boost lignocellulose degradation by increasing the activities of key enzymes during straw composting (Wei et al., 2019).
Unlike a fungal consortium, cellulolytic nitrogen-fixing bacteria (CNFB) do not need a nitrogen (N2) source partner as they have the ability to satisfy their nitrogen requirements through fixation of atmospheric N2 (Leschine and Canale-Parola, 1989). The completion of a composting process and subsequent use of the compost as a soil conditioner are extremely reliant on the capacity of the microflora present during the composting process. The addition of CNFB to the composting material showed several benefits in different domains like agriculture and waste management (Wei et al., 2019; Kausar et al., 2011; Abdulla, 2007).
Despite large number of past reviews on organic waste composting, this study is the first to present a detailed and comprehensive review of the potential application of CNFB in LCCR composting. Thus, various studies on CNFB, including screening of the microorganisms and methods for essays on the enzyme activity, have been reviewed. In addition, the effectiveness of compost application in sustainable agriculture has been discussed.
Section snippets
Worldwide production of lignocellulosic crop residues
LCCRs refer to the plant biomass such as rice straw, wheat straw, sorghum, corn stover, sugarcane bagasse, etc. Driven by agricultural industrialization and an increasing demand for food worldwide, billions of tons of LCCRs are produced every year and constitute the most abundant biomass on earth (Zheng et al., 2014).
Worldwide availability of LCCRs varies based on the plant species and this availability is different among countries and regions. Sugarcane is the leading agricultural plant in the
Carbon-rich components of the lignocellulosic agricultural residues
Lignocellulosic biomass predominantly consists of a complex mixture of three natural carbohydrate biopolymers - cellulose (30%–50%), hemicelluloses (20%–40%), and lignin (10%–30%), that are closely linked by physical forces and chemical forces. The amount of cellulose, hemicelluloses, and lignin in dry crop residues varies from species to species (Table 1) and also depends on the cultivation conditions, the geographical location and the age of plants (Pérez et al., 2002). In addition, cellulose
Pre-treatment of the lignocellulosic crop residues for composting
Lignocellulosic biomass is resistant to microbial degradation due to its inherent complexity and heterogeneity. Therefore, enhancement of LCCR composting requires pretreatment of LCCRs, which disrupts the tightly packed structure of the lignocellulosic biomass and exposes cellulose and hemicelluloses to enzymatic attack (Agbor et al., 2011).
We can classify the major pre-treatment methods for LCCR composting into three different categories: physical methods, chemical and biological approaches.
Microbial degradation of lignocellulosic crop residues
Several microorganisms have the ability to decompose lignocellulose, which is ultimately converted into carbon dioxide and water under aerobic conditions, and into carbon dioxide, methane, and water under anaerobic conditions. Most of the lignocellulolytic microorganisms are bacteria or fungi, but anaerobic lignocellulose-degrading protozoa have also been identified in the rumen (Gupta et al., 2012; Béguin and Aubert, 1994).
Based on an intensive research on the lignocellulolytic system of the
Definitions
CNFB are a group of microorganisms that produce cellulases to break down the cellulose molecules into simple sugars, and produce nitrogenase to catalyze the conversion of atmospheric nitrogen (N2) to fixed nitrogen (NH3). Such species are helpful in transforming lignocellulosic and other cellulosic resources into commodities and fertilizers with increased nutritional quality of carbohydrates and higher levels of assimilable nitrogen (Hardy and Wiley, 1990).
Waterbury et al. (1983) were the first
Definitions
Composting is the microbial transformation of different biodegradable materials into nutrient-rich products that can enhance the soil health, the soil productivity, and the soil's ability to absorb and retain water and crop nutrients. The composting process is controlled by physicochemical factors, physiological factors and microbiological factors. This ancient practice has long been used to treat solid wastes so that the organic material can be easily degraded through the natural process of
Lignocellulosic crop residue composting by CNFB
Studies have revealed that key microorganisms involved in nitrogen transformation during the composting process are mostly cellulose-decomposing bacteria. Nitrogen-fixing bacterial genera, such as Stenotrophomonas, Xanthomonas, Pseudomonas, Klebsiella, Alcaligenes, Achromobacter, and Caulobacter, isolated from the compost materials (Pepe et al., 2013), have been previously described to be involved in organic matter degradation during composting (Insam and de Bertoldi, 2007). While composting
Some applications of compost in sustainable agriculture
Compost is the final product of aerobic microbial decomposition of biodegradable materials. While chemical fertilizers improve the soil only by adding nutrients, the use of mature compost in agriculture improves the soil's organic matter content, resistance to soil erosion, groundwater keeping ability, carbon sequestration, nutrient content, and plant disease resistance (Pergola et al., 2018).
Compost is a natural, safe and environment-friendly option for the recovery of organic fertility in the
Conclusions and future perspectives
Inoculation of compost materials with CNFB has been shown to be the most environment-friendly and the quickest way to recycle lignocellulosic biomass back into the soil and enhance the physicochemical properties and the biological properties of the soil. Bacteria with both cellulolytic and nitrogen-fixing traits reduce the overall time required for composting, and accelerate the composting performance of the lignocellulosic waste by decreasing the C/N ratio, reducing odors and adding more value
Declaration of competing interest
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
Acknowledgments
This project was funded by the national first-class discipline program of the Light Industry Technology and Engineering (LITE2018-11). The authors wish to thank our all laboratory colleagues for their constructive advice and help.
References (173)
- et al.
Biotechnological application of thermotolerant cellulose-decomposing bacteria in composting of rice straw
Ann. Agric. Sci.
(2016) - et al.
Biomass pretreatment: fundamentals toward application
Biotechnol. Adv.
(2011) - et al.
Optimum moisture levels for biodegradation of mortality composting envelope materials
Waste Manag.
(2008) - et al.
Evaluation of thermophilic fungal consortium for organic municipal solid waste composting
Bioresour. Technol.
(2014) - et al.
Production of cellulases from Aspergillus niger NS-2 in solid state fermentation on agricultural and kitchen waste residues
Waste Management
(2012) - et al.
The biological degradation of cellulose
FEMS Microbiol. Rev.
(1994) - et al.
Importance of chemical pretreatment for bioconversion of lignocellulosic biomass
Renew. Sust. Energ. Rev.
(2014) - et al.
Chapter 1 - Introduction
Processing of biomass with hydrothermal and supercritical water
Hyperthermophilic composting reduces nitrogen loss via inhibiting ammonifiers and enhancing nitrogenous humic substance formation
Sci. Total Environ.
(2019)
Hyperthermophilic composting significantly decreases N2O emissions by regulating N2O-related functional genes
Bioresour. Technol.
Isolation of cellulolytic bacteria from the gastro-intestinal tract of Achatina fulica (Gastropoda: Pulmonata) and their evaluation for cellulose biodegradation
Int. Biodeterior. Biodegrad.
Electrogenerated alkaline hydrogen peroxide for rice straw pretreatment to enhance enzymatic hydrolysis
Bioresour. Technol.
Acetylene reduction by nitrogen-fixing preparations from Clostridium pasteurianum
BBA - Gen. Subj.
Impact of compost, vermicompost and biochar on soil fertility, maize yield and soil erosion in Northern Vietnam: a three year mesocosm experiment
Sci. Total Environ.
Sustainability of agricultural and rural waste management
Sustainable Industrial Design and Waste Management
The effect of aeration rate on forced-aeration composting of chicken manure and sawdust
Bioresour. Technol.
Municipal wastewater treatment
Environmental Microbiology
Vermicompost as a soil supplement to improve growth, yield and fruit quality of tomato (Lycopersicum esculentum)
Bioresour. Technol.
Carbon cycling by cellulose-fermenting nitrogen-fixing bacteria
Adv. Space Res.
Biological treatment of organic materials for energy and nutrients production—anaerobic digestion and composting
Adv. Bioenergy
Lignin
Cereal Straw as a Resource for Sustainable Biomaterials and Biofuels
Nitrogen fixation by Bacillus strains isolated from the rhizosphere of Ammophila arenaria
Plant Soil
Enhancement of rice straw composting by lignocellulolytic actinomycete strains
Int. J. Agric. Biol.
Plant Cell-Wall Degrading Hydrolytic Enzymes of Gluconacetobacter Diazotrophicus
Symbiosis
Isolation and characterization of cellulolytic nitrogen fixing Azotobacter species from wheat rhizosphere of Khyber Pakhtunkhwa
World Appl. Sci. J.
Optimization of parameters for the production of cellulase from Achromobacter xylosoxidans BSS4 by solid-state fermentation
Electron. J. Biol.
Comparison of chemical pretreatment methods for cellulosic biomass
APCBEE Procedia
Rice straw and wheat straw. Potential feedstocks for the biobased economy potential feedstocks for the biobased economy
Excretion of ammonium by a nifL mutant of Azotobacter vinelandii fixing nitrogen
Appl. Environ. Microbiol.
Ammonia in the atmosphere: a review on emission sources, atmospheric chemistry and deposition on terrestrial bodies
Environ. Sci. Pollut. Res.
The complex physiology of Cellvibrio japonicus xylan degradation relies on a single cytoplasmic β-xylosidase for xylo-oligosaccharide utilization
Mol. Microbiol.
Evolution of high cellulolytic activity in symbiotic Streptomyces through selection of expanded gene content and coordinated gene expression
PLoS Biol.
Caldicellulosiruptor kristjanssonii sp. nov., a cellulolytic, extremely thermophilic, anaerobic bacterium
Int. J. Syst. Bacteriol.
Hyperthermophilic pretreatment device and its application on improving decomposition effect for chicken manure and rice straw aerobic composting
Nongye Gongcheng Xuebao/Transactions Chinese Soc. Agric. Eng.
Spectroscopic evidence for hyperthermophilic pretreatment intensifying humification during pig manure and rice straw composting
Bioresour. Technol.
Composting of rice straw with effective microorganisms (EM) and its influence on compost quality
Iran. J. Environ. Heal. Sci. Eng.
High level expression of Acidothermus cellulolyticus β-1, 4-endoglucanase in transgenic rice enhances the hydrolysis of its straw by cultured cow gastric fluid
Biotechnol. Biofuels
Diversity of free-living nitrogen fixing Streptomyces in soils of the badlands of South Dakota
Microbiol. Res.
Assessment of biological nitrogen fixation
Fertil. Res.
Fungal bioconversion of lignocellulosic residues; opportunities & perspectives
Int. J. Biol. Sci.
Cellulase activities in biomass conversion: measurement methods and comparison
Crit. Rev. Biotechnol.
Field evaluation of source-separated compost and Coneg model procurement specifications for Connecticut Dot projects
Genetic engineering of Trichoderma reesei cellulases and their production
Microb. Biotechnol.
FAOSTAT Data
FAOSTAT, Crops
Treating Straw for Animal Feeding: The Beckmann Method
International Union of Pure Commission on Biotechnology: measurement of cellulase activities
Pure Appl. Chem.
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