Four different alkaline treatments for isolation of cellulose microfibrils from vascular bundles of banana rachis were comparatively studied. Isolated cellulose microfibrils were characterized using ...high performance anion exchange chromatography for neutral sugar composition, as well as attenuated total reflection Fourier transform infrared spectroscopy, transmission electron microscopy, X-ray and electron diffraction and solid-state
13C NMR. The cellulose microfibrils treated with peroxide alkaline, peroxide alkaline–hydrochloric acid or 5
wt% potassium hydroxide had average diameters of 3–5
nm, estimated lengths of several micrometers. Although the interpretation of their structure is difficult because of the low cristallinity, X-ray diffraction,
13C NMR and ATR-FTIR results suggested that cellulose microfibrils from banana rachis could be either interpreted as cellulose IV
1 or cellulose Iβ. The specimens treated with a more concentrated KOH solution (18
wt%) were still microfibrillated but their structure was converted to cellulose II.
Xylitol is a pentahydroxy sugar-alcohol which exists in a very low quantity in fruits and vegetables (plums, strawberries, cauliflower, and pumpkin). On commercial scale, xylitol can be produced by ...chemical and biotechnological processes. Chemical production is costly and extensive in purification steps. However, biotechnological method utilizes agricultural and forestry wastes which offer the possibilities of economic production of xylitol by reducing required energy. The precursor xylose is produced from agricultural biomass by chemical and enzymatic hydrolysis and can be converted to xylitol primarily by yeast strain. Hydrolysis under acidic condition is the more commonly used practice influenced by various process parameters. Various fermentation process inhibitors are produced during chemical hydrolysis that reduce xylitol production, a detoxification step is, therefore, necessary. Biotechnological xylitol production is an integral process of microbial species belonging to Candida genus which is influenced by various process parameters such as pH, temperature, time, nitrogen source, and yeast extract level. Xylitol has application and potential for food and pharmaceutical industries. It is a functional sweetener as it has prebiotic effects which can reduce blood glucose, triglyceride, and cholesterol level. This review describes recent research developments related to bioproduction of xylitol from agricultural wastes, application, health, and safety issues.
Thermomechanical pulp (TMP) has great potential in packaging paper production. However, the lack of raw materials and relatively low physical performance of TMP due to the high lignin content limit ...its large-scale application. In this study, we use thermomechanical pulping of plant residues combined with ozone treatment to cut costs and improve the physical performance of TMP. During TMP pulping, the effects of the ozone on the structure and physical properties of fibers were investigated. Changing the ozone dosage showed a distinct effect on the surface lignin content and morphology of fibers. In the oxidation process, the structure of lignin was damaged and the physical properties were improved significantly. Moreover, it also proved the feasibility of the mass production of this approach. The fibers of this type have a great future as complementary raw material to recycled fibers to produce packaging paper in applications of paper products of higher quality.
Display omitted
•The lignin content on the fiber surface reduced after ozone treatment.•The physical properties of the TMP were significantly improved by ozone treatment.•Energy consumptions declines in the pulping process after ozone treatment.•Mass-production of high-quality cellulose fibers from plant residues is possible.
Microplastics (MPs) are considered to influence fundamental biogeochemical processes, but the effects of plant residue-MP interactions on soil carbon turnover in urban greenspaces are virtually ...unknown. Here, an 84-day incubation experiment was constructed using four types of single-vegetation-covered soils (6 years), showing that polystyrene MP (PSMP) pollution caused an unexpectedly large increase in soil CO2 emissions. The additional CO2 originating from highly bioavailable active dissolved organic matter molecules (<380 °C, predominantly polysaccharides) was converted from persistent carbon (380–650 °C, predominantly aromatic compounds) rather than PSMP derivatives. However, the priming effect of PSMP derivatives was weakened in plant-driven soils (resistivity: shrub > tree > grass). This can be explained from two perspectives: (1) Plant residue-driven humification processes reduced the percentage of bioavailable active dissolved organic matter derived from the priming effects of PSMPs. (2) Plant residues accelerated bacterial community succession (dominated by plant residue types) but slowed fungal community demise (retained carbon turnover-related functional taxa), enabling specific enrichment of glycolysis, the citric acid cycle and the pentose phosphate pathway. These results provide a necessary theoretical basis to understand the role of plant residues in reducing PSMP harm at the ecological level and refresh knowledge about the importance of biodiversity for ecosystem stability.
The Paleolithic-Neolithic transition has been hotly debated for decades. In our study, plant starch residue analysis suggests that the occupants of Pigeon Mountain (Locality QG10) exploited several ...edible plant resources including cereals, legumes, nuts, and underground storage organs (USOs). A post-hunting-gathering living style could be observed, with advanced plant processing techniques, but without any cultivation. Here we propose an Organized Food Supply system, to interpret the development of cereal utilization in this part of North China in prehistory. In this system, the occupants gathered various edible plant materials, including a large proportion of cereals, returned to their base camp, processed and consumed them but left a surplus for the future consumption and logistic needs for each fieldwork team. On this model, they were reaping wild plants but were not sowing them as future crops. Among the food materials, cereals are easily prepared, stored, and transported, and were thus one of the first choices of high-mobility fieldwork teams. This strategy is more significant in arid or semi-arid environments because of the difficulty of instant food acquisition, and subsequently influenced the occupants’ exploitation of plant resources.
A major challenge of the 21st century will be to generate transportation fuels using feedstocks such as lignocellulosic waste materials as a substitute for existing fossil and nuclear fuels. The ...advantages of lignocellulosics as a feedstock material are that they are abundant, sustainable and carbon-neutral. To improve the economics of producing liquid transportation fuels from lignocellulosic biomass, the development of value-added products from lignin, a major component of lignocellulosics, is necessary. Lignins produced from black liquor through the fractionation of sugarcane bagasse with soda and organic solvents have been characterised by physical, chemical and thermal means. The soda lignin fractions have different physico-chemical and thermal properties from one another. Some of these properties have been compared to bagasse lignin extracted with aqueous ethanol.
Soil sickness (SS) is the rise of negative conditions for plant vegetative and reproductive performances induced into the soil by the plant itself. In natural ecosystems, plant ecologists refer to SS ...as negative plant-soil feedback (NPSF). Scope of this review is to provide an updated picture of the current SS understanding by an explicit comparison between agro-ecosystems and natural plant communities. By an extensive analysis of literature we found that SS is pervasive in agro-ecosystems, occurring in 111 cultivated plants belonging to 41 taxonomic families. Concerning NPSF in natural plant communities, we found evidence of this phenomenon for a total of 411 vascular plants belonging to 72 plant families. NPSF occurs in most of the terrestrial ecosystems, including tropical and temperate forests, coastal sand dunes, old fields and grassland, deserts, as well as heathland and tundra. Three main hypotheses have been proposed to explain SS: (i) soil nutrient depletion or imbalance; (ii) buildup of soilborne pathogen and parasite populations, coupled with a shift in soil microbial community composition; (iii) release of phytotoxic and autotoxic compounds during decomposition of crop residues. Evidences from both agroecosystems and natural plant communities undoubtedly ruled out the nutrient deficiency as a primary causal factor. Moreover, the massive use of mineral fertilizers, especially under intensive cultivation systems, appears an incorrect strategy that only exacerbates the decline of soil quality by inducing acidification and salinization. Soilborne pathogens are often isolated from symptomatic plants and many autotoxic compounds have been identified and quantified from sick soil. However, both the pathogenic and autotoxicity hypotheses are still unable to fully explain the species-specificity, as well as the long durability of SS observed in field conditions. The recent discovery that extracellular DNA (exDNA) has self-inhibitory effects, support the autotoxicity hypothesis, nevertheless this is a totally new topic, and more solid and systematic field investigations are needed. A better understanding of the causes of SS is a necessary step to develop eco-friendly solutions to overcome this problem.
Returning rice straw and leguminous green manure alone or in combination to soil is effective in improving soil fertility in South China. Despite the popularity of this practice, our understanding of ...the underlying processes for straw and manure combined application is relatively poor. In this study, rice straw (carbon (C)/nitrogen (N) ratio of 63), green manure (hairy vetch, C/N ratio of 14), and their mixtures (C/N ratio of 25 and 35) were added into a paddy soil, and their effects on soil N availability and C or N loss under waterlogged conditions were evaluated in a 100-d incubation experiment. All plant residue treatments significantly enhanced CO2 and CH4 emissions, but decreased N2O emission. Dissolved organic C (DOC) and N (DON) and microbial biomass C in soil and water-soluble organic C and N and mineral N in the upper aqueous layer above soil were also enhanced by all the plant residue treatments except the rice straw treatment, and soil microbial biomass N and mineral N were lower in the rice straw treatment than in the other treatments. Changes in plant residue C/N ratio, DOC/DON ratio, and cellulose content significantly affected greenhouse gas emissions and active C and N concentrations in soil. Additionally, the treatment with green manure alone yielded the largest C and N losses, and incorporation of the plant residue mixture with a C/N ratio of 35 caused the largest net global warming potential (nGWP) among the amended treatments. In conclusion, the co-incorporation of rice straw and green manure can alleviate the limitation resulting from only applying rice straw (N immobilization) or the sole application of leguminous green manure (high C and N losses), and the residue mixture with a C/N ratio of 25 is a better option because of lower nGWP.
Display omitted
•Effects of tree leaf and root residues on SOC mineralization were studied.•Root residue generally induced stronger negative priming than leaf residue.•Priming effect induced by ...residue input varied greatly with tree species.•Tree chemical composition controlled the magnitude of priming.
Changes in soil organic carbon (SOC) decomposition in response to fresh plant residue inputs (i.e., the priming effect) represent an important biogeochemical process controlling soil C dynamics. However, the variations in priming induced by the addition of leaf and root residues with different chemical compositions among tree species and their potential mechanisms are not yet well known. We conducted a 90-day incubation experiment and explored the responses of priming effect to the 13C-labelled leaf and root residues of Cyclobalanopsis glauca, Cunninghamia lanceolata, Acacia confusa and Manglietia fordiana and further examined the relationships between the priming and the chemical compositions of these tree residues. Our results show that tree residue inputs decreased native SOC mineralization by approximately 20–59%, and root residues induced more pronounced or comparable negative priming effects than leaf residues. Moreover, the intensities of the negative priming were greater in soils supplemented with C. glauca and C. lanceolata residues than in soils supplemented with A. confusa and M. fordiana residues. The magnitude of the negative priming effect was inversely correlated with K content in plant residues but positively correlated with lignin content, lignin/N ratio and C/N ratio. The structural equation model indicates that residue K content, lignin/N ratio, as well as plant-derived microbial biomass carbon (MBC) and dissolved organic carbon (DOC) were the key derivers of the priming, with these drivers together explaining approximately 82% of the variations in the cumulative priming effects. Overall, our study suggests that tree root residues generally induce a more negative priming than tree leaf residues, but the extent of priming varied with tree species. Chemical properties of tree residues can help to improve our understanding of the priming mechanisms that could lead to a more precise estimation of SOC dynamics.
The importance of food fibres has led to the development of a large and potential market for fibre-rich products and ingredients and nowadays there is a trend to find new sources of dietary fibre ...(DF), such as agronomic by-products that have traditionally been undervalued. Although there have been great achievements in this research field, further investigations are needed for designing ‘new food systems’ that consider the precise functionality of DF from both technological and physiological points of view.
Present knowledge about different aspects of DF and future potential applications of fibres and/or its components as functional foods or ingredients will be the focus of this report.
PDF
