Solid-state production of cellulase by Melanoporia sp. CCT 7736: a new strain isolated from coconut shell (Cocos nucifera L.)

Abstract

Background:The use of residues in industrial processing is expanding due to their low cost and abundant availability. Coconut shell is generated in large amounts in tropical areas due to the fruit processing and the coconut water consumption. In the present work, a new microbial strain was isolated from the coconut shell powder, molecularly identified as Melanoporia sp. CCT 7736 and applied for cellulase production in solid-state fermentation using the green coconut shell powder as substrate. Results:The complete production process was optimized. Fermentation time was only 24 h, and the enzyme produced presented maximal activity at neutral pH (6.5) and 60 °C. The maximal enzyme activity after extraction optimization was 7.5 IU/gds (international units of enzyme activity per gram of dry solid). For the enzyme extraction, the rotation velocity, the extraction time, the temperature, and the solvent volume (buffer) were optimized using response surface methodology (RSM). The best results for the enzyme extraction were obtained at 250 rpm (orbital shaker) at 30 °C using 13.79 mL of a sodium acetate buffer (200 mM) at pH 6.5 after 10 min. Delignification pretreatment was not necessary since this fungus strain was able to degrade the lignin. Conclusions:To the best of our knowledge, this work is the first report of cellulase production by Melanoporia sp. CCT 7736. Good results were obtained without the need for expensive pretreatment usually applied to lignocellulosic residues because the strain was isolated from coconut shell powder, and it is well adapted to this kind of substrate. The enzyme presented maximum activity at neutral pH instead of acidic pH as reported for the majority of industrial cellulases. The use of lignified coconut shell and the optimal pH at neutral values are the main advantages of the enzyme produced by Melanoporia sp. CCT 7736. In addition, the enzyme showed good stability during storage even at the crude broth and without any cryoprotection.

Cellulases and xylanases production by endophytic fungi by solid state fermentation using lignocellulosic substrates and enzymatic saccharification of pretreated sugarcane bagasse

“…Several studies regarding cellulolytic enzymes production using different microorganisms, substrates and culture conditions are found in literature, with a wide variation in the activities obtained (Hansen et al, 2015;de Oliveira et al, 2016;Yadav et al, 2016).…”

Screening of cellulolytic bacteria from rotten wood of Qinling (China) for biomass degradation and cloning of cellulases from Bacillus methylotrophicus

“…Indeed, fungi exhibit a strong ability to secret considerable extracellular enzymes including multi-cellulases, which was the main reason why numerous studies had been conducted on fungi producing cellulases, such as Trichoderma reesei RUT-C30 [8], Trichoderma koningiopsis FCD3-1 [9], and Melanoporia sp. CCT 7736 [10]. However, it has also been found that the culture and genetically modification of fungi were relatively more difficult to achieve than bacteria, which seriously hindered the practical application of fungi and fungi-producing cellulases to celluloses hydrolyzation [11,12].…”

Optimization of high endoglucanase yields production from polypore fungus, Microporus xanthopus strain KA038 under solid-state fermentation using green tea waste

“…However, because of the higher cost, using a large amount of organic nitrogen source such as yeast extract was not the most efficient method for industrial enzyme production. Our research did not show the best result of endoglucanase production, however, it indicated the potential of polypore fungi M. xanthopus strain KA038 to produce better cellulolytic activity compared with other polypore fungi such as Melanoporia sp., Pycnoporus sanguineus , Pycnoporus coccineus and Coriolus versicolor (Montoya et al, 2015; Onofre et al, 2015; Chuwech et al, 2016; de Oliveira et al, 2016). Thus, this result demonstrated that M. xanthopus was a remarkable species of polypore fungi in producing endoglucanase activity.…”