Biodegradation of lignin and nicotine with white rot fungi for the delignification and detoxification of tobacco stalk

Abstract

BackgroundTobacco 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.ResultsThe 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 · L−1), manganese peroxidase (100.95 U · L−1) and laccase (745.65 U · 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 · mL−1, 0.45 U · mL−1 and 0.35U · 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.ConclusionsOur 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 different oxidative enzymes and chemical products detected during the degradation indicated a possible pathway for the utilization of tobacco stalk.Electronic supplementary materialThe online version of this article (doi:10.1186/s12896-016-0311-8) contains supplementary material, which is available to authorized users.

Enzymatic Degradation of Lignin in Soil: A Review

“…White-rot fungi are the most effective bio-degraders of lignocellulosic biomass (e.g., Phanerochaete chrysosporium) and can degrade lignin faster than other microorganisms. Su et al reported that the degradation rate of lignin by Phanerochaete chrysosporium in tobacco stalk was 53.75% in 15 days [33].…”

Lignin Degradation by Fungal Pretreatment: A Review

“…TUFC20056 50% of lignin removal [12] Milled wheat straw Penicillium chrysogenum 27.4% lignin mineralization [54] Milled wheat straw Fusarium oxysporum 23.5% lignin mineralization [54] Milled wheat straw Fusarium solani 22.6% lignin mineralization [54] involved in the fungal attack which decreases methoxy, phenolic, and aliphatic content of lignin. These reactions also cleave aromatic rings, and forms new carbonyl groups [40,41]. Selective type of degradations involves degradation of lignin and hemicellulose compared to cellulose.…”

“…White-rot fungi are identified to grow on woody and herbaceous plants. The most examined white-rot fungi for lignin reduction in a selective way are P. chrysosporium and Phlebia while in a non-selective way Trametes versicolor decrease lignin [10,11,41].…”

“…The best place for the growth of soft-rot fungi are compost, soil, piles of woodchips, straw [44]. Soft-rot fungi can reduce cellulose and hemicellulose of woody plants in a slowly way, whereas lignin reduction is somewhat slight [41,45]. The adaptation of soft-rot fungi in various temperature, different pH and limited oxygen is higher than other fungi.…”

Biotransformation of lignin: Mechanisms, applications and future work

“…These processes typically break down large molecules of lignin by applying harsh conditions, such as high temperature, high pressure, and extreme pH 33 while catalysts are usually used. Several classes of microorganisms have been found to possess lignin degradation capabilities, such as white rot fungi, [35][36][37] bacteria, 38,39 and protists. 34 Although the reaction rate and efficiency are high, intensive energy input is typically required.…”