Isolation of aerobic cultivable cellulolytic bacteria from different regions of the gastrointestinal tract of giant land snail Achatina fulica

Abstract

The enzymatic hydrolysis of cellulose by cellulases is one of the major limiting steps in the conversion of lignocellulosic biomass to yield bioethanol. To overcome this hindrance, significant efforts are underway to identify novel cellulases. The snail Achatina fulica is a gastropod with high cellulolytic activity, mainly due to the abundance of glycoside hydrolases produced by both the animal and its resident microbiota. In this study, we partially assessed the cellulolytic aerobic bacterial diversity inside the gastrointestinal tract of A. fulica by culture-dependent methods and evaluated the hydrolytic repertoire of the isolates. Forty bacterial isolates were recovered from distinct segments of the snail gut and identified to the genus level by 16S rRNA gene sequence analysis. Additional phenotypic characterization was performed using biochemical tests provided by the Vitek2 identification system. The overall enzymatic repertoire of the isolated strains was investigated by enzymatic plate assays, containing the following substrates: powdered sugarcane bagasse, carboxymethylcellulose (CMC), p-nitrophenyl-β-D-glucopyranoside (pNPG), p-nitrophenyl-β-D-cellobioside (pNPC), 4-methylumbelliferyl-β-D-glucopyranoside (MUG), 4-methylumbelliferyl-β-D-cellobioside (MUC), and 4-methylumbelliferyl-β-D-xylopyranoside (MUX). Our results indicate that the snail A. fulica is an attractive source of cultivable bacteria that showed to be valuable resources for the production of different types of biomass-degrading enzymes.

Effect of Different Lignocellulosic Diets on Bacterial Microbiota and Hydrolytic Enzyme Activities in the Gut of the Cotton Boll Weevil (Anthonomus grandis)

“…Several researchers reported Stenotrophomona sp. as cellulolytic (Huang et al, 2012; Talia et al, 2012; Pinheiro et al, 2015). In addition, members of Micrococcus sp.…”

Biochemical Characterization of Streptomyces sp. I1.2 Secretome Reveals the Presence of Multienzymatic Complexes Containing Cellulases and Accessory Enzymes

“…I1.2 Cultivation for Enzyme Production Streptomyces sp. strain I1.2 was isolated from the intestinal lumen of the land snail A. fulica in a screening for cultivable cellulolytic aerobic bacteria [17]. Firstly, Streptomyces sp.…”

“…These include endo-glucanases from Helix pomatia [49], from Dolabella auricularia [50], and more recently, from Ampullaria crossean [51] and Pomacea canaliculata [52]. In addition to their endo-genous enzymatic repertoire, recent studies revealed that land snails contain a complex and adaptable microbiota that potentially accounts for their great digestive efficiency [17,53,54]. In addition, a metagenomic analysis of A. fulica crop-resident microbiota identified a great number of sequences coding for biomass-degrading enzymes (36 %), including cellulases and hemicellulases [45].…”

“…I1.2) from the intestinal tract of the giant snail Achatina fulica [17]. This strain is able to grow well in crystalline cellulose or sugarcane bagasse as sole carbon sources and secretes multiple endo-glucanases and cellobiohydrolases to the culture supernatant.…”

Novel Butyric Acid Fermentation Strains and Their Performance in Fermenting Rice Straw by Pure and Mixed Culturing

“…The colony formed on the solid medium of C4 strain is white and its diameter was about 1 mm. The edge of colony was zigzag, and there was a large degrading circle around it showing good degradability of cellulose [26] . As shown in Fig.…”