Purification and characterization of a thermostable alkaline cellulase produced by Bacillus licheniformis 380 isolated from compost

Abstract

During composting processes, the degradation of organic waste is accomplished and driven by a succession of microbial populations exhibiting a broad range of functional competencies. A total of 183 bacteria, isolated from a composting process, were evaluated for cellulase activity at different temperatures (37, 50, 60, and 70°C) and pH values. Out of the 22 isolates that showed activity, isolate 380 showed the highest cellulase activity. Its ability to produce cellulase was evaluated in culture medium supplemented with carboxymethyl cellulose, microcrystalline cellulose, wheat straw, and rice husk. The culture medium supplemented with carboxymethyl cellulose induced higher enzyme activity after 6 hours of incubation (0.12 UEA mL -1 min -1 ). For wheat straw and rice husk, the results were 0.08 UEA mL -1 min -1 for both, while for microcrystalline cellulose, 0.04 UEA mL -1 min -1 were observed. The highest carboxymethyl cellulase activity was observed at 60°C (0.14 UEA mL -1 min -1 ) for both crude and partially purified enzyme after 30 and 120 min of incubation, respectively. Alkalinization of the medium was observed during cultivation in all substrates. The cellulase had a molecular mass of 20 kDa determined by SDS-Page. Isolate 380 was identified as Bacillus licheniformis. This work provides a basis for further studies on composting optimization.

Novel Synergistic Mechanism for Lignocellulose Degradation by a Thermophilic Filamentous Fungus and a Thermophilic Actinobacterium Based on Functional Proteomics

“…For instance, high temperature can accelerate lignocellulose deconstruction and reduce potential contamination and pathogenic risk ( Li et al, 2011 ; Li, 2015 ). Some studies have been conducted to explore thermotolerant and/or alkaline-resistant enzymes with various industrial application potentials, such as xylanases and cellulases ( De Marco et al, 2017 ; Kumar et al, 2018 ; Zheng et al, 2018 ).…”

Thermotolerant glycosyl hydrolases-producing Bacillus aerius CMCPS1 and its saccharification efficiency on HCR-laccase (LccH)-pretreated corncob biomass

“…Alkaline cellulases from alkaliphilic Bacillus strain KSM-635, which is active at pH values higher than 8.0 under mesophilic conditions (30-37 °C), has already been reported [30]. Moreover, thermostable alkaline cellulases (pH 3.0-9.0) from Bacillus licheniformis 380, isolated from compost, have been purified and characterized [31]. In addition, acid-tolerant cellulases (pH 4.8) have been reported by several other studies on Nectria catalinensis [32].…”

Aceleração do Processo de Compostagem

“…A celulase, apesar de ter sido citada na literatura como uma substância bastante viável para acelerar o processo de compostagem, ainda não foi utilizada em muitos estudos com esta finalidade. Porém, devido à sua potencial aplicação nesta área (Liu et al, 2018;Marco et al, 2017;Reyes-Torres et al, 2018;Tuomela et al, 2000), foi tratada neste tópico separadamente.…”

“…De acordo com Reyes-Torres et al (2018) a aplicação de celulase na mistura de compostagem é uma forma inovadora de melhorar a degradação da celulose e promover a formação de substâncias húmicas, que é um dos principais requisitos para um produto final de alta qualidade Marco et al (2017), em seu trabalho sobre a purificação e caracterização de uma celulase alcalina termoestável, produzida por Bacillus licheniformis 380, isolado de um composto, concluíram que a mesma pode ter potencial aplicação em biotecnologia, acelerando a degradação da matéria orgânica, degradando resíduos celulósicos durante a fase de degradação primária, fornecendo também uma base para estudos sobre a otimização da compostagem. Liu et al (2018) avaliaram os efeitos da celulase e de um inóculo microbiano no processo de compostagem de resíduos verdes.…”