Enhanced extracellular production of laccase in Coprinopsis cinerea by silencing chitinase gene.

Laccase, a copper-containing polyphenol oxidase, is an important green biocatalyst. In this study, Laccase Lcc5 was homologous recombinantly expressed in Coprinopsis cinerea and a novel strategy of silencing chitinase gene expression was used to enhance recombinant Lcc5 extracellular yield. Two critical chitinase genes, ChiEn1 and ChiE2, were selected by analyzing the transcriptome data of C. cinerea FA2222, and their silent expression was performed by RNA interference (RNAi). It was found that silencing either ChiEn1 or ChiE2 reduced sporulation and growth rate, and increased cell wall sensitivity, but had no significant effect on mycelial branching. Among them, the extracellular laccase activity of the ChiE2-silenced engineered strain Cclcc5-antiChiE2-5 and the control Cclcc5-13 reached the highest values (38.2 and 25.5 U/mL, respectively) at 250 and 150 rpm agitation speeds, corresponding to productivity of 0.35 and 0.19 U/mL·h, respectively, in a 3-L fermenter culture. Moreover, since Cclcc5-antiChiE2-5 could withstand greater shear forces, its extracellular laccase activity was 2.6-fold higher than that of Cclcc5-13 when the agitation speed was all at 250 rpm. To our knowledge, this is the first report of enhanced recombinant laccase production in C. cinerea by silencing the chitinase gene. This study will pave the way for laccase industrial production and accelerate the development of a C. cinerea high-expression system. KEY POINTS: • ChiEn1 and ChiE2 are critical chitinase genes in C. cinerea FA2222 genome. • Chitinase gene silencing enhanced the tolerance of C. cinerea to shear forces. • High homologous production of Lcc5 is achieved by fermentation in a 3-L fermenter.

Self-Compounded Nanocomposites: toward Multifunctional Membranes with Superior Mechanical, Gas/Oil Barrier, UV-Shielding, and Photothermal Conversion Properties.

Nanocomposites combine multiple favorable properties to achieve intriguing functionalities, but the formation of nanocomposites with only one constituent with the inclusion of multiple superior properties is still not known. Herein, novel self-compounded nanocomposite membranes from one single polymer-cellulose cinnamate (CCi)-with multiple outstanding properties are reported. The self-compounded membranes contain two distinct morphologies as CCi nanoparticles (CCi-NPs) and a CCi polymer matrix, while CCi-NPs are either firmly embedded in the CCi matrix or fused with adjacent CCi-NPs. The unique self-compounded nanostructure endows the membranes with a tensile strength of 94 MPa and Young's modulus of 3.1 GPa. The water vapor permeability, oxygen permeability, and oil permeability reach as low as (0.94 ± 0.03) × 10-11 g m-1 s-1 Pa-1, (8.48 ± 2.39) ×10-13 cm3·cm/cm2·s·cmHg, and 0.008 ± 0.003 g mm m-2 day-1, respectively. Moreover, self-compounded CCi nanocomposite membranes also demonstrate UV-shielding and photothermal conversion properties. UVB and UVC light are entirely blocked, while UVA light is partly blocked. The temperature increases from room temperature to 120 °C within 1 min under UV irradiation. In addition, CCi membranes also show remarkable thermal and humidity resistance. Based on these outstanding properties, CCi membranes are applied as food packaging materials. This work offers a new avenue to construct nanocomposites with multiple superior properties from one constituent, which is promising for diverse applications.

Facile fabrication of pH-responsive nanoparticles from cellulose derivatives via Schiff base formation for controlled release.

A controllable drug delivery system demonstrates a promising tool for diverse biomedical applications. In this work, a group of amphiphilic macromolecules was designed and prepared via Schiff base reactions between 2,3-dialdehyde cellulose (DAC) with oleylamine and amino-containing compounds. Benefiting from the self-assemble process of these amphiphilic macromolecules in the poor solvent, a group of novel pH-responsive nanoparticles (NPs) were facilely fabricated by using nanoprecipitation dropping technique. The high amount of aldehyde groups on DAC chains enabled immobilization of tunable amounts of amine compounds (up to 1.67 mmol/g) in the NPs. Furthermore, the Schiff base bonds in NPs allowed the efficient release of the drug in acidic tumor microenvironment by cleaving the Schiff base linkages. This study demonstrates the formation of a group of novel pH-sensitive and drug-loadable NPs, which provide a simple and efficient drug delivery system for the potential application for cancer treatment.