Enhancing digestibility of Miscanthus using lignocellulolytic enzyme produced by Bacillus

Guo, Haipeng; Wu, Yanwen; Hong, Chuntao; Chen, Houming; Chen, Xuantong; Zheng, Bingsong; Jiang, Dean; Qin, Wensheng

doi:10.1016/j.biortech.2017.09.034

Cited by 26 publications

(24 citation statements)

References 47 publications

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“…The cellulose and hemicellulose contents were measured according to the method of Guo and colleagues (). Briefly, the sample (0.1 g) was extracted twice with 1.5 ml hot water, once with 1.5 ml absolute ethanol and once with 1.5 ml acetone at 65°C for 30 min.…”

Section: Experiments Proceduresmentioning

confidence: 99%

Pretreatment of Miscanthus with biomass‐degrading bacteria for increasing delignification and enzymatic hydrolysability

Guo

Zhao

Chen

et al. 2019

Microbial Biotechnology

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Summary Biomass recalcitrance is still a main challenge for the production of biofuels and high‐value products. Here, an alternative Miscanthus pretreatment method by using lignin‐degrading bacteria was developed. Six efficient Miscanthus‐degrading bacteria were first cultured to produce laccase by using 0.5% Miscanthus biomass as carbon source. After 1–5 days of incubation, the maximum laccase activities induced by Miscanthus in the six strains were ranged from 103 to 8091 U l−1. Then, the crude enzymes were directly diluted by equal volumes of citrate buffer and added Miscanthus biomass to a solid concentration at 4% (w/v). The results showed that all bacterial pretreatments significantly decreased the lignin content, especially in the presence of two laccase mediators (ABTS and HBT). The lignin removal directly correlated with increases in total sugar and glucose yields after enzymatic hydrolysis. When ABTS was used as a mediator, the best lignin‐degrading bacteria (Pseudomonas sp. AS1) can remove up to 50.1% lignin of Miscanthus by obtaining 2.2‐fold glucose yield, compared with that of untreated biomass. Therefore, this study provided an effective Miscanthus pretreatment method by using lignin‐degrading bacteria, which may be potentially used in improving enzymatic hydrolysability of biomass.

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Section: Experiments Proceduresmentioning

confidence: 99%

Pretreatment of Miscanthus with biomass‐degrading bacteria for increasing delignification and enzymatic hydrolysability

Guo

Zhao

Chen

et al. 2019

Microbial Biotechnology

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“…Fermenting at 30 • C in the incubator with a rotate speed of 200 rpm, 1.0 mL of each sample was taken for enzymatic activity analysis every 24 h. Cultured cells were centrifuged at 15,000× g for 10 min and the supernatants were obtained. Sodium azide (0.05%) was added to prevent the microbial contamination during the hydrolysis [55]. All of the experiments were performed in triplicates.…”

Section: Enzymatic Hydrolysismentioning

confidence: 99%

“…Enzymatic activities of CMCase were measured based on the microplate method [55] modified to 1ml volume with carboxymethyl cellulose as a substrate respectively. Briefly, 100 µL of diluted crude enzyme liquid was mixed with 200 µL 1.0% of various substance solution (pH 5.0) in 5ml test-tube, acting in the water bath at 50 • C for 30 min and instantly cooled down adding 600 µL of the DNS reagent and heated in boiling water for 5 min.…”

Section: Enzymatic Hydrolysismentioning

confidence: 99%

Genomic, Transcriptomic and Enzymatic Insight into Lignocellulolytic System of a Plant Pathogen Dickeya sp. WS52 to Digest Sweet Pepper and Tomato Stalk

et al. 2019

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Dickeya sp., a plant pathogen, causing soft rot with strong pectin degradation capacity was taken for the comprehensive analysis of its corresponding biomass degradative system, which has not been analyzed yet. Whole genome sequence analysis of the isolated soft-rotten plant pathogen Dickeya sp. WS52, revealed various coding genes which involved in vegetable stalk degradation-related properties. A total of 122 genes were found to be encoded for putative carbohydrate-active enzymes (CAZy) in Dickeya sp. WS52. The number of pectin degradation-related genes, was higher than that of cellulolytic bacteria as well as other Dickeya spp. strains. The CAZy in Dickeya sp.WS52 contains a complete repertoire of enzymes required for hemicellulose degradation, especially pectinases. In addition, WS52 strain possessed plenty of genes encoding potential ligninolytic relevant enzymes, such as multicopper oxidase, catalase/hydroperoxidase, glutathione S-transferase, and quinone oxidoreductase. Transcriptome analysis revealed that parts of genes encoding lignocellulolytic enzymes were significantly upregulated in the presence of minimal salt medium with vegetable stalks. However, most of the genes were related to lignocellulolytic enzymes, especially pectate lyases and were downregulated due to the slow growth and downregulated secretion systems. The assay of lignocellulolytic enzymes including CMCase and pectinase activities were identified to be more active in vegetable stalk relative to MSM + glucose. However, compared with nutrient LB medium, it needed sufficient nutrient to promote growth and to improve the secretion system. Further identification of enzyme activities of Dickeya sp.WS52 by HPLC confirmed that monosaccharides were produced during degradation of tomato stalk. This identified degradative system is valuable for the application in the lignocellulosic bioenergy industry and animal production.

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“…The rate of digestibility and accessibility is mainly determined by the factors of cellulose crystallinity, accessible surface area, and the amount of association between cellulose, hemicellulose, and lignin [ 3 ]. There are currently two main strategies that are used to change the specific surface area and crystallinity of cellulose via either hemicellulose removal or biomass delignification [ 4 , 5 ]. Biomass delignification has been extensively reported to expose the composition of polysaccharides via various pretreatments methods, such as microwave irradiation [ 6 ], alkaline [ 7 ], organic solvent [ 8 ], laccase pretreatment [ 9 ], and wet oxidation [ 10 ].…”

Section: Introductionmentioning

confidence: 99%

“…Biological pretreatments using microorganisms in nature have received growing attention as alternatives to physical and chemical pretreatments [ 16 ]. It has been reported that the digestibility of Miscanthus was enhanced by the removal of hemicellulose, after a bacterial xylanase pretreatment [ 4 ]. Xylan removal can also help to reduce the suppression of enzymes from xylo-oligomers, and the amount of required accessory enzymes [ 17 ].…”

Section: Introductionmentioning

confidence: 99%

Improving enzymatic digestibility of wheat straw pretreated by a cellulase-free xylanase-secreting Pseudomonas boreopolis G22 with simultaneous production of bioflocculants

Guo¹,

Hong²,

Zheng³

et al. 2018

Biotechnol Biofuels

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BackgroundXylan removal by bacterial pretreatments has been confirmed to increase the digestibility of biomass. Here, an effective xylan removal technique has been developed to enhance the digestibility of wheat straw and simultaneously produce bioflocculants by a cellulase-free xylanase-secreting strain, Pseudomonas boreopolis G22.ResultsThe results indicated that P. boreopolis G22 is an alkaliphilic strain which can secrete abundant amounts of xylanase. This xylanase had activity levels of 2.67–1.75 U mL−1 after an incubation period of 5–25 days. The xylanase showed peak activity levels at pH 8.6, and retained more than 85% relative activity in the pH range of 7.2–9.8. After 15 days of cultivation, the hemicellulose contents of the wheat straw were significantly decreased by 32.5%, while its cellulose contents were increased by 27.3%, compared to that of the control. The maximum reducing sugars released from the 15-day-pretreated wheat straw were 1.8-fold higher than that of the untreated wheat straw, under optimal enzymatic hydrolysis conditions. In addition, a maximum bioflocculant yield of 2.08 g L−1 was extracted from the fermentation broth after 15 days of incubation. The aforementioned bioflocculants could be used to efficiently decolorize a dye solution.ConclusionsThe results indicate that the cellulase-free xylanase-secreting P. boreopolis G22 may be a potential strain for wheat straw pretreatments. The strain G22 does not only enhance the enzymatic digestibility of wheat straw, but also simultaneously produces a number of bioflocculants that can be used for various industrial applications.

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Enhancing digestibility of Miscanthus using lignocellulolytic enzyme produced by Bacillus

Cited by 26 publications

References 47 publications

Pretreatment of Miscanthus with biomass‐degrading bacteria for increasing delignification and enzymatic hydrolysability

Pretreatment of Miscanthus with biomass‐degrading bacteria for increasing delignification and enzymatic hydrolysability

Genomic, Transcriptomic and Enzymatic Insight into Lignocellulolytic System of a Plant Pathogen Dickeya sp. WS52 to Digest Sweet Pepper and Tomato Stalk

Improving enzymatic digestibility of wheat straw pretreated by a cellulase-free xylanase-secreting Pseudomonas boreopolis G22 with simultaneous production of bioflocculants

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