Effect of highly branched hyphal morphology on the enhanced production of cellulase in Trichoderma reesei DES-15.

Ronglin He,Shulin Chen,Dongyuan Zhang,Chen Li,Lijuan Ma

doi:10.1007/s13205-016-0516-5

Abstract

The morphology of Trichoderma reesei is a vitally important factor for cellulase productivity. This study investigated the effect of hyphal morphology on cellulase production in the hyper-cellulolytic mutant, T. reesei DES-15. With a distinct morphology, T. reesei DES-15 was obtained through Diethyl sulfite (DES) mutagenesis. The hyphal morphology of DES-15 batch-cultured in a 5-L fermentor was significantly shorter and more branched than the parental strain RUT C30. The cellulase production of DES-15 during batch fermentation was 66 % greater than that of RUT C30 when cultured the same conditions. DES-15 secreted nearly 50 % more protein than RUT C30. The gene expression level of a set of genes (cla4, spa2, ras2, ras1, rhoA, cdc42, and racA) known to be involved in hyphae growth and hyphal branching was measured by quantitative real-time PCR. The transcriptional analysis of these genes demonstrated that a decrease in gene expressions might contribute to the increased hyphal branching seen in DES-15. These results indicated that the highly branching hyphae in DES-15 resulted in increased cellulase production, suggesting that DES-15 may be a good candidate for use in the large-scale production of cellulase.Electronic supplementary materialThe online version of this article (doi:10.1007/s13205-016-0516-5) contains supplementary material, which is available to authorized users.

Highlights

Much research has been performed with the aim of developing renewable energy sources as alternatives to fossil fuels
This study investigated the effect of hyphal morphology on cellulase production in the hyper-cellulolytic mutant, T. reesei Diethyl sulfite (DES)-15
4 College of Biotechnology, Tianjin University of Science and Technology, Tianjin 300457, People’s Republic of China these genes demonstrated that a decrease in gene expressions might contribute to the increased hyphal branching seen in DES-15. These results indicated that the highly branching hyphae in DES-15 resulted in increased cellulase production, suggesting that DES-15 may be a good candidate for use in the large-scale production of cellulase

Summary

Introduction

Much research has been performed with the aim of developing renewable energy sources as alternatives to fossil fuels. The high cost of lignocellulosic enzymes for lignocellulosic degradation is one of the most important limiting factors in the bio-refinery of lignocellulosic biomass (Wilson 2009). The enzymes are secreted into fermentation broths at high levels following submerged cultivation. Submerged cultivations permit the easy acquisition of secreted enzymes for downstream fermentation processes (Liu et al 2013). Submerged cultures are generally employed for the largescale production of filamentous fungi. Recognized as complex systems, submerged cultures could be influenced by many external factors, some of which can affect the hyphal morphology of filamentous fungi (Kaup et al 2008). In most filamentous fungal fermentation, it is generally believed that the level of productivity is dependent on the ability of the fungus to achieve an optimal

Methods

Results

Conclusion