title: Comprehensive analysis of the cellulolytic system reveals its potential for deconstruction of lignocellulosic biomass in a novel Streptomyces sp.
abstract: The giant snail Achatina fulica is considered an invasive species in most territories in which it was introduced, due to its ability to process a large amount of lignocellulose as a consequence of the presence of a cellulolytic-associated microflora. Streptomyces are well known as crucial agents in the decomposition of complex polymers in soil environments and also as cellulolytic symbionts commonly associated with herbivore insects. Here, we employed a combination of genomic and biochemical tools for a detailed evaluation of the cellulolytic potential of Streptomyces sp. I1.2, an aerobic bacterium isolated from the intestinal lumen of A. fulica in a screening for cellulolytic bacteria. Genomic analysis revealed that the ratio and diversity of CAZy domains and GH families coded by Streptomyces sp. I1.2 are comparable to those present in other highly cellulolytic bacteria. After growth on crystalline cellulose or sugarcane bagasse as sole carbon sources, the functionality of several genes encoding endoglucanases, cellobiohydrolases, xylanases, CBMs, and one β-glucosidase were confirmed by the combination of enzymatic activity measurements, zymography, TLC, and cellulose-binding assays. The endoglucanases secreted by this isolate were stable at 50 °C and exhibited activity over a broad pH range between 4.0 and 8.0. The endoglucanases and cellobiohydrolases secreted by Streptomyces sp. I1.2 exhibited specific activities that were similar to the levels present in a commercial cellulase preparation from Trichoderma reesei, while I1.2 xylanase levels were even 350 % higher. The results presented here show that Streptomyces sp. I1.2 is promising for future biotechnological applications, since it is able to produce endoglucanases, cellobiohydrolases, and xylanases in appreciable amounts when grown on a low-cost residue such as sugarcane bagasse.
authors.affiliation: Diretoria de Metrologia Aplicada às Ciências da Vida, Instituto Nacional de Metrologia, Qualidade e Tecnologia - Inmetro, Rio de Janeiro, RJ, Brazil.|Laboratório de Ultraestrutura Celular Hertha Meyer, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, UFRJ, Rio de Janeiro, RJ, Brazil.
authors.forename: Guilherme L
authors.initials: GL
authors.lastname: Pinheiro
authors.affiliation: Laboratório de Metabolismo Macromolecular Firmino Torres de Castro, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil.
authors.forename: Allan C
authors.initials: AC
authors.lastname: de Azevedo-Martins
authors.affiliation: Instituto de Biologia Roberto Alcântara Gomes, Departamento de Bioquímica, Universidade do Estado do Rio de Janeiro, Rio de Janeiro, RJ, Brazil.
authors.forename: Rodolpho M
authors.initials: RM
authors.lastname: Albano
authors.affiliation: Laboratório de Ultraestrutura Celular Hertha Meyer, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, UFRJ, Rio de Janeiro, RJ, Brazil.
authors.forename: Wanderley
authors.initials: W
authors.lastname: de Souza
authors.affiliation: Laboratório de Ultraestrutura Celular Hertha Meyer, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, UFRJ, Rio de Janeiro, RJ, Brazil. susanafrases@biof.ufrj.br.
authors.forename: Susana
authors.initials: S
authors.lastname: Frases
mesh_terms: D000818:Animals; D002244:Carbon / Q000378:metabolism; D002482:Cellulose / Q000378:metabolism*; D049851:Gastropoda / Q000382:microbiology; D006026:Glycoside Hydrolases / Q000032:analysis*; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D013302:Streptomyces / Q000201:enzymology* / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D013696:Temperature
chemical_list: D002244:Carbon; D002482:Cellulose; C027433:bagasse; D006026:Glycoside Hydrolases
keywords: Achatina fulica; Cellobiohydrolases; Endoglucanases; Genomics; Streptomyces; Sugarcane bagasse