De novo transcriptome assembly of the bamboo snout beetle Cyrtotrachelus buqueti reveals ability to degrade lignocellulose of bamboo feedstock

Abstract

BackgroundThe bamboo weevil Cyrtotrachelus buqueti, which is considered a pest species, damages bamboo shoots via its piercing–sucking mode of feeding. C. buqueti is well known for its ability to transform bamboo shoot biomass into nutrients and energy for growth, development and reproduction with high specificity and efficacy of bioconversion. Woody bamboo is a perennial grass that is a potential feedstock for lignocellulosic biomass because of its high growth rate and lignocellulose content. To verify our hypothesis that C. buqueti efficiently degrades bamboo lignocellulose, we assessed the bamboo lignocellulose-degrading ability of this insect through RNA sequencing for identifying a potential route for utilisation of bamboo biomass.ResultsAnalysis of carbohydrate-active enzyme (CAZyme) family genes in the developmental transcriptome of C. buqueti revealed 1082 unigenes, including 55 glycoside hydrolases (GH) families containing 309 GHs, 51 glycosyltransferases (GT) families containing 329 GTs, 8 carbohydrate esterases (CE) families containing 174 CEs, 6 polysaccharide lyases (PL) families containing 11 PLs, 8 auxiliary activities (AA) families containing 131 enzymes with AAs and 17 carbohydrate-binding modules (CBM) families containing 128 CBMs. We used weighted gene co-expression network analysis to analyse developmental RNA sequencing data, and 19 unique modules were identified in the analysis. Of these modules, the expression of MEyellow module genes was unique and the module included numerous CAZyme family genes. CAZyme genes in this module were divided into two groups depending on whether gene expression was higher in the adult/larval stages or in the egg/pupal stages. Enzyme assays revealed that cellulase activity was highest in the midgut whereas lignin-degrading enzyme activity was highest in the hindgut, consistent with findings from intestinal gene expression studies. We also analysed the expression of CAZyme genes in the transcriptome of C. buqueti from two cities and found that several genes were also assigned to CAZyme families. The insect had genes and enzymes associated with lignocellulose degradation, the expression of which differed with developmental stage and intestinal region.ConclusionCyrtotrachelus buqueti exhibits lignocellulose degradation-related enzymes and genes, most notably CAZyme family genes. CAZyme family genes showed differences in expression at different developmental stages, with adults being more effective at cellulose degradation and larvae at lignin degradation, as well as at different regions of the intestine, with the midgut being more cellulolytic than the hindgut. This degradative system could be utilised for the bioconversion of bamboo lignocellulosic biomass.Electronic supplementary materialThe online version of this article (10.1186/s13068-018-1291-9) contains supplementary material, which is available to authorized users.

Bamboo lignocellulose degradation by gut symbiotic microbiota of the bamboo snout beetle Cyrtotrachelus buqueti

“…From the co-cultures, 2-mL samples were withdrawn at 1, 2, 3, 4, 5 and 6 days for assays determining lignocellulolytic enzyme activity. Endoglucanase (EC 3.2.1.4), exoglucanase (EC 3.2.1.91), β-glucosidase (EC 3.2.1.21), lignin peroxidase (LiP)-like, laccase-like, and xylanase enzyme activities were analysed as previously described by Luo et al [18]. Briefly, carboxymethyl cellulose (CMC), microcrystalline cellulose (MCC), salicin, veratryl alcohol (VA), 2,2′-azino-bis (ABTS) and xylan were used as substrates to determine endoglucanase, exoglucanase, β-glucosidase, LiP-like, laccase-like and xylanase, respectively.…”

“…The bamboo snout beetle, Cyrtotrachelus buqueti , is a serious pest of bamboo species, which include Phyllostachys pubescens , Neosinocalamus affinis , Bambusa textilis and Dendrocalamus farinosus [17]. Cyrtotrachelus buqueti also exhibits high lignocellulolytic enzyme activity [18]. However, to date, no studies have investigated the role of snout beetle gut microbiota in lignocellulose degradation, as has been done for termites [8] and other species of beetles [4–7].…”

Evaluation of hydrolytic enzyme activities from digestive fluids of Anthonomus grandis (Coleoptera: Curculionidae)

“…This could explain the lower activities observed in the midgut in comparison to the other analyzed sections. In addition, the β‐glucosidase activity was mainly detected in the hindgut (S3), a section that harbors most of the gut symbionts and that usually displays most of cellulose degradation (Li & Brune, 2005; Luo, Li, Liao, & Yang, 2018; Pothula et al, 2019; J. Sun, S‐Y.…”

Comparative Genomics Uncovers the Genetic Diversity and Characters of Veillonella atypica and Provides Insights Into Its Potential Applications

“…Additionally, the differences in CAZymes among the nine V. atypica strains were attributed to the CAZyme components derived from the accessory clusters ( Figure 2C). For example, V. atypica NCTC11830, V. atypica ACS-134-V-Col7a, and V. atypica ACS-049-V-Sch6 were found to harbor one orthologous gene belonging to AA6, which is 1,4-benzoquinone reductase and involved in the biodegradation of aromatic compounds (Luo et al, 2018). CMW7756B harbored one orthologous gene belonging to GT83 (Figure 2C).…”