Encapsulation of Trichoderma harzianum with nanocellulose/carboxymethyl cellulose nanocomposite

Abstract

This study proposes the use of green matrices of cellulose nanocrystals (CNC) and a nanocomposite of CNC with carboxymethyl cellulose (CMC) for efficiently encapsulating the plant biocontrol agent Trichoderma harzianum. Beads containing spores of the microorganism were produced by dripping dispersions of the polymers into a CaCl₂ coagulation bath, resulting in the crosslinking of CNC chains by Ca²⁺ ions. SEM micrographs evidenced the T. harzianum spores in the encapsulation matrices. X-ray microtomography confirmed the random distribution of the microorganism within the polymeric matrix and the presence of internal pores in the CNC:CMC:spores beads. Encapsulation in the CNC:CMC nanocomposite favored growth of the fungus after 10 days of storage at room temperature, which could be attributed to the presence of internal pores and to the extra carbon source provided by the CMC. The results indicated that CNC:CMC nanocomposites are promising materials for protecting and delivering microbial inoculants for agricultural applications.

Keywords: Carboxymethyl cellulose; Cellulose nanocrystals; Encapsulation; Microbial inoculant.