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Abstract The macroscopic co-combustion characteristics of tobacco stalk, low rank coal, and their blends were investigated in a custom-designed macro-TGA. The interaction between tobacco stalk and coal during co-combustion, as well as effect of the proportion of the two, were also studied. The results showed that increasing the proportion of tobacco stalk was more effective in reducing the burnout temperature than the ignition temperature. The ignition temperature of the tobacco stalk (254 °C to 321 °C) varied greatly at different heating rates compared with coal (408 °C to 412 °C). The mixing of tobacco stalk and coal produced an inhibitory interaction before ignition, and gradually transformed into a promotion with the increase in temperature. The promoting interaction was most significant for the blends with tobacco stalk weight percentage of 70%. The results obtained in this study may be used to the understanding of the combustion of tobacco stalk/coal and also provide a basis for further applying tobacco stalks on industrial boilers with high efficiency. [ABSTRACT FROM AUTHOR]

Background: Tobacco stalk is one kind of abundant crop residues in China. The high lignification of tobacco stalk increases its reusing cost and the existing of nicotine will cause serious pollution. The biodegradation of lignocellulosic biomass has been demonstrated to be an environmental and economical approach for the utilization of plant stalk. Meanwhile, many nicotine-degrading microorganisms were found in nature. However, microorganisms which could degraded both nicotine and lignin haven't been reported. Therefore, it's imperative to find some suitable microorganisms to break down lignin and simultaneously remove nicotine in tobacco stalk. Results: The nicotine in tobacco stalk could be degraded effectively by Trametes versicolor, Trametes hirsute and Phanerochaete chrysosporium. The nicotine content in tobacco stalk was lowered to below 500 mg/kg (a safe concentration to environment) after 10 days of fermentation with Phanerochaete chrysosporium and Trametes versicolor, and 15 days with Trametes hirsute. The degradation rate of lignin in the fermented tobacco stalk was 37.70, 51.56 and 53.75% with Trametes versicolor, Trametes hirsute and Phanerochaete chrysosporium,respectively. Meanwhile, 24.28% hemicellulose was degraded by Phanerochaete chrysosporium and 28.19% cellulose was removed by Trametes hirsute. Through the enzyme activity analysis, the main and highest ligninolytic enzymes produced by Phanerochaete chrysosporium, Trametes hirsute and Trametes versicolor were lignin peroxidase (88.62 U x L-1), manganese peroxidase (100.95 U x L-1 ) and laccase (745.65 U x L-1 ). Meanwhile, relatively high and stable cellulase activity was also detected during the fermentation with Phanerochaete chrysosporium, and the highest endoglucanase, exoglucanase and filter paper enzyme activities were 0.38 U x mL-1, 0.45U x mL-1 and 0.35U x mL-1, respectively. Moreover, the products in the fermentation of tobacco stalk with P. chrysosporium were identified with GC-MS, besides the chemicals produced in the degradation of lignin and nicotine, some small molecular valuable chemicals and fatty acid were also detected. Conclusions: Our study developed a new method for the degradation and detoxification of tobacco stalk by fermentation with white rot fungi Phanerochaete chrysosporium and Trametes hirsute. The differentoxidative enzymes and chemical products detected during the degradation indicated a possible pathway for the utilization of tobacco stalk. [ABSTRACT FROM AUTHOR]

Tobacco stalks are an abundant biomass resource which are otherwise treated as waste. In this work, the effect of hydrothermal carbonization temperature and time on the structures, chemical compositions and combustion characteristics of hydrochars obtained from tobacco stalks were evaluated. The carbon content, higher heating value, and energy yield increased with accompanying decrease in hydrogen and oxygen contents with the increase of treatment temperature and time. The evolution of the H/C and O/C atomic ratios indicated dehydration and devolatilization processes occurred during hydrothermal carbonization. The weight loss, combustion range and characteristic temperatures of tobacco stalks were significantly modified after hydrothermal carbonization, resulting in higher ignition temperatures and higher energy density. The kinetics model, Coats–Redfern method revealed the activation energy of hydrochars in zone 2 and 3 were among 43.7–74.8 kJ/mol and 46.7–85.8 kJ/mol, respectively. Our results show that hydrothermal carbonization reaction can facilitate transforming tobacco stalks into energy-rich solid fuel. [ABSTRACT FROM AUTHOR]

Tobacco stalk (TS), which is one type of lignocellulosic material, has a xylan content of up to 21.9%. Lignocellulose can be used to produce xylooligosaccharides (XOs). XOs are dietary fibers that have prebiotic activity. This study aimed to produce XOs from tobacco stalk xylan using xylanase from Streptomyces sp. BO 3.2. After the TS was delignified, the xylan was extracted using the alkali method. The delignification process, which used 1% natrium hypoclorite (NaOCl), decreased the lignins from 32.93% to 18.15%. Xylan extraction was conducted using 10% natrium hydoroxide (NaOH); this extraction produced xylan of 15.53% (w/w). The xylanase produced by Streptomyces sp. BO 3.2 on a 0.5% TS medium had 5.92 U/mL of activity, with the optimum condition occurring at pH 5.5 and a temperature of 60 °C. The xylanase was stable, at temperature 4 °C and 30 °C for 120 hours. The xylanase Streptomyces sp. BO 3.2 was capable of hydrolyzing 2% TS xylan and 2% beechwood xylan during the first, third, sixth, and twelfth hours of incubation time; it also produced XOs with degrees of polymerization (DP) of 2.18 and 2.15, respectively. A Thin layer chomatography (TLC) analysis indicated that the hydrolysis products were XOs with the absence of xylose, glucose, and arabinose. [ABSTRACT FROM AUTHOR]

Abstract: The study investigated the termite resistance, physical and mechanical properties of particleboard made from waste tobacco (Nicotiana tabacum L.) stalk and Paraserianthes falcataria wood particles. Boards containing at least 25% tobacco stalk exhibited excellent termite resistance in laboratory no-choice feeding test against the Asian subterranean termite, Coptotermes gestroi Wasmann. Underground ground field exposure tests also showed that particleboard containing at least 50% tobacco stalk provided excellent protection against Philippine subterranean termites. Termite resistance of particleboard containing tobacco stalk is most likely due to the presence of residual nicotine in the samples. Addition of P. falcataria wood particles in all proportions used in this study resulted in boards with internal bond, stiffness and strength properties above the minimum set by the European standard EN 312-2 (1996) for general use particleboards. Boards containing 50–100% tobacco stalk showed high water absorption and thickness swelling after 24 h soaking in water. Results of the study showed that tobacco stalk can be used as an alternative material either alone or in combination with wood particles for the manufacture of particleboard with direct positive impact on disposal problem and efficient utilization of this waste biomass. [Copyright &y& Elsevier]

Although the essential role of bacteria in tobacco fermentation process, in Cuba never has been identified the genera present in the cured tobacco for wrapper, neither the variables that affect their populations. This knowledge will be aid to management the process in which the microorganisms are involved. The objective of this research was to determine the relationship between population density of the bacterial genera with dominant populations in cured tobacco leaves of different leaf positions of the stalk and nicotine concentrations and pH values in these environments. The isolation and generic identification of bacterial microbiota was done for each tobacco leaves positions and pH values and nicotine concentrations were obtained too. Members of the genus Bacillus were isolated in all leaf positions. Staphylococcus members were not isolated at the «leaf» tobacco stalk positions. Representatives of the Arthrobacter genus were isolated only in both leaves positions «cutters» and «leaf». Bacillus populations were always higher than the other genera isolated. Nicotine was significantly increase and pH was show a slight nonsignificant (p<0,01) decrease, the population density of bacteria isolated in all genres decreased from lowest to highest leaf positions. The regression model reveals that the decrease in population density of bacterial genera that is appraised to climb different leaves positions is more related to the increased of nicotine concentration in the leaves than with the variation of pH. [ABSTRACT FROM AUTHOR]

Folivory is the best studied plant-herbivore interaction, but it is unclear whether the signaling and resistance traits important for the defense of leaves are also important for other plant parts. Larvae of the tobacco stem weevil, Trichobaris mucorea, burrow into stems of Nicotiana attenuata and feed on the pith. Transgenic N. attenuata lines silenced in signaling and foliar defense traits were evaluated in a 2-year field study for resistance against attack by naturally occurring T. mucorea larva. Plants silenced in early jasmonic acid (JA) biosynthesis (antisense [as]-lipoxygenase3 [lox3]; inverted repeat [ir]-allene oxide cyclase), JA perception (as-coronatine insensitive1), proteinase inhibitors (ir-pi), and nicotine (ir-putrescine methyl-transferase) direct defenses and lignin (ir-cad) biosynthesis were infested more frequently than wild-type plants. Plants unable to emit C6 aldehydes (as-hpl) had lower infestation rates, while plants silenced in late steps in JA biosynthesis (ir-acyl-coenzyme A oxidase, ir-opr) and silenced in diterpene glycoside production (ir-geranylgeranyl pyrophosphate synthase) did not differ from wild type. Pith choice assays revealed that ir-putrescine methyl-transferase, ir-coronatine insensitive1, and ir-lox3 pith, which all had diminished nicotine levels, were preferred by larvae compared to wild-type pith. The lack of preference for ir-lox2 and ir-cad piths, suggest that oviposition attraction and vascular defense, rather than pith palatability accounts for the higher attack rates observed for these plants. We conclude that traits that influence a plant's apparency, stem hardness, and pith direct defenses all contribute to resistance against this herbivore whose attack can be devastating to N. attenuata's fitness. [ABSTRACT FROM AUTHOR]