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

Chaobing Luo,Yaojun Yang,Wencong Long,Hong Liao,Ximeng Xiao,Ying Chen,Chun Fu,Yuanqiu Li

doi:10.1186/s13068-019-1411-1

Chaobing Luo, Yaojun Yang + Show 6 more

Open Access

https://doi.org/10.1186/s13068-019-1411-1

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Abstract

BackgroundGut symbiotic microbiota plays a critical role in nutrient supply, digestion, and absorption. The bamboo snout beetle, Cyrtotrachelus buqueti, a common pest of several bamboo species, exhibits high lignocellulolytic enzyme activity and contains various CAZyme genes. However, to date, no studies have evaluated the role of gut symbiotic microbiota of the snout beetle on bamboo lignocellulose degradation. Therefore, the present study investigated the role of gut symbiotic microbiota of C. buqueti on bamboo lignocellulose degradation.ResultsGut symbiotic microbiota of female (CCJ), male (XCJ), and larvae (YCJ) beetles was used to treat bamboo shoot particles (BSPs) in vitro for 6 days. Scanning electron microscopy (SEM) revealed significant destruction of the lignocellulose structure after treatment, which was consistent with the degradation efficiencies of CCJ, XCJ, and YCJ for cellulose (21.11%, 17.58% and 18.74%, respectively); hemicellulose (22.22%, 27.18% and 34.20%, respectively); and lignin (19.83%, 24.30% and 32.97%, respectively). Gut symbiotic microbiota of adult and larvae beetles was then identified using 16sRNA sequencing, which revealed that four microbes: Lactococcus, Serratia, Dysgonomonas and Enterococcus, comprise approximately 84% to 94% of the microbiota. Moreover, the genomes of 45 Lactococcus, 72 Serratia, 86 Enterococcus and 4 Dysgonomonas microbes were used to analyse resident CAZyme genes. These results indicated that gut symbiotic microbiota of adult and larvae C. buqueti is involved in the lignocellulose degradation traits shown by the host.ConclusionsThis study shows that the gut symbiotic microbiota of C. buqueti participates in bamboo lignocellulose degradation, providing innovative findings for bamboo lignocellulose bioconversion. Furthermore, the results of this study will allow us to further isolate lignocellulose-degrading microbiota for use in bamboo lignocellulose bioconversion.

Highlights

Gut symbiotic microbiota plays a critical role in nutrient supply, digestion, and absorption
In Costelytra zealandica (New Zealand grass grub), various hindgut bacteria participate in lignocellulose degradation [4] and some lignocellulose-degrading bacteria have been isolated from the larvae of the scarab beetle Pachnoda marginata [5]
The degradation of bamboo shoots (Bambusa emeiensis) by snout beetle gut microbiota was investigated in vitro, and the results revealed that the microbiota of both adult and larval C. buqueti has lignocellulose-degrading ability

Summary

Introduction

Gut symbiotic microbiota plays a critical role in nutrient supply, digestion, and absorption. To date, no studies have evaluated the role of gut symbiotic microbiota of the snout beetle on bamboo lignocellulose degradation. Many insects, including termites, wood-feeding roaches, beetles, wood wasps, leaf-shredding aquatic insects, silverfish and leaf-cutting ants, have been shown to exhibit lignocellulose degradation ability [1]. In phytophagous insects, such as termites, beetles and wood bees, lignocellulose digestion requires cooperation between insects and symbiotic microorganisms in the insect gut, especially bacteria, protozoa, fungi, and yeasts [3]. These studies show that there is significant involvement of insect symbiotic microbes in lignocellulose degradation

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