Encapsulation of Trichoderma harzianum conidia as a method of conidia preservation at room temperature and propagation in submerged culture

ABSTRACT

The objective of the present work was to develop a method for the preservation of T. harzianum conidia at room temperature and the immobilised conidia propagation in submerged culture. This was accomplished by immobilising the strain in sodium alginate capsules (white capsules) and subsequently propagating them in a column bubble reactor (green capsules). Three capsule diameters were tested (micro, medium and large capsules), which were produced by emulsion internal gelation and dripping methods. Tested variables were the immobilised conidia propagation in submerged culture for free conidia production, the immobilised conidia viability throughout the time (two years), the resistance of the encapsulated conidia to the UV irradiation of short and long wavelength, and the antagonistic effect of the encapsulated T. harzianum against four phytopathogenic fungi. It was found that the medium capsules (1.5 ± 0.3 mm) favoured the massive production of released conidia in submerged culture and that the higher the density of conidia per capsule, the greater the protection against the ultraviolet irradiation. Regarding the conidia preservation in calcium alginate, a viability loss of around 30% was observed two years after storage at environmental temperature in both white and green capsules; along the two years that the viability of conidia was analyzed, the purity of the formulation was corroborated. The results presented here show the efficacy of the green and white capsules for T. harzianum preservation at room temperature for a long period of time.

KEYWORDS:

• Bubble column reactor
• Trichoderma harzianum preservation
• encapsulation
• phytopathogenic fungi

Acknowledgments

The authors would like to thank B. María de Lourdes Rojas Morales from the LANSE, for technical and steadfast help. The authors thank the comments of the reviewers; they helped us substantially to improve the presentation of our research.

Disclosure statement

No potential conflict of interest was reported by the authors.

ORCID

Jorge E. Ibarra http://orcid.org/0000-0002-1013-8260

Josefina Barrera-Cortés http://orcid.org/0000-0001-9348-4275

Additional information

Funding

Research supported by Consejo Nacional de Ciencia y Tecnología [grant number INFRA-2012-01-188339].