Trichoderma microsclerotia and methods of making
Inventors
Jackson, Mark A. • Mascarin, Gabriel M. • Kobori, Nilce Naomi
Assignees
Empresa Brasileira de Pesquisa Agropecuaria EMBRAPA • US Department of Agriculture USDA
Publication Number
US-9642372-B2
Publication Date
2017-05-09
Expiration Date
2035-07-17
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Abstract
Disclosed is an invention that relates to the formation of microsclerotial propagules by mycoparasitic fungi and the use of those microsclerotia for plant disease control. Representative microsclerotia propagules formed are from fungal species Trichoderma harzianum, Trichoderma lignorum, Trichoderma viridae, Trichoderma reesei, Trichoderma koningii, Trichoderma pseudokoningii, Trichoderma polysporum, Trichoderma hamatum, and Trichoderma asperellum.
Core Innovation
The invention relates to the formation of microsclerotial propagules by mycoparasitic fungi, specifically fungi of the genus Trichoderma, and the use of those microsclerotia for plant disease control. The microsclerotia are melanized, compact hyphal aggregates that are highly resistant to desiccation and can germinate hyphally or sporogenically to produce conidia, which are infective to target fungal plant pathogens.
The problem being solved arises from the constraints associated with existing Trichoderma biopesticide production methods, primarily the reliance on solid substrate-produced aerial conidia, which require weeks for production and drying, thus increasing production costs and complicating scale-up. Additionally, liquid culture methods for submerged conidia and chlamydospore production have suffered from low yields, long fermentation times, poor desiccation tolerance, and storage stability, limiting their commercial adoption. There is a need for an efficient, feasible liquid culture production technology to produce high quality, persistent Trichoderma-based products.
The invention addresses these challenges by disclosing isolated microsclerotia of Trichoderma species formed in liquid culture media, with defined carbon and nitrogen source concentrations conducive to microsclerotia formation. The invention includes compositions comprising these microsclerotia with agronomically acceptable carriers wherein upon rehydration the microsclerotia germinate to produce conidia. Methods for producing high concentrations of desiccation tolerant microsclerotia and submerged conidia through inoculation of liquid culture media, controlled incubation, aeration, and collection of biomass are disclosed. The microsclerotia demonstrate storage stability after drying and upon application to seeds and retain biocontrol efficacy against various plant pathogenic fungi.
Claims Coverage
The patent includes two independent claims covering a composition comprising Trichoderma microsclerotia and methods for producing fungi with high concentrations of microsclerotia and submerged conidia.
Composition comprising Trichoderma microsclerotia with agronomically acceptable carrier
A composition comprising microsclerotia of a Trichoderma species combined with an agronomically acceptable carrier, wherein said microsclerotia, upon rehydration, germinate hyphally or sporogenically to produce conidia.
Method for producing high concentration of desiccation tolerant fungal microsclerotia
A method comprising inoculating a liquid culture medium with fungal propagules of Trichoderma species, wherein the nitrogen source concentration is between 8 grams/liter and 40 grams/liter and the carbon source concentration is greater than 40 grams/liter, incubating to allow microsclerotia production, and collecting the resulting microsclerotia.
Method for producing fungi with high concentration of microsclerotia and submerged conidia using a bioreactor
A method comprising inoculating a liquid culture medium with fungal propagules of Trichoderma species, incubating in a bioreactor with aeration maintaining dissolved oxygen near or above zero and air flow at least 0.1 Vair/Vculture media to produce microsclerotia and submerged conidia, and collecting the resulting biomass, achieving about 10.8×10^6 microsclerotia per liter and about 1.9×10^12 submerged conidia per liter.
The independent claims focus on a composition of Trichoderma microsclerotia capable of germination to produce conidia and detailed methods for producing high concentrations of desiccation tolerant microsclerotia and submerged conidia via liquid culture fermentation using specific nutrient concentrations and controlled bioreactor conditions.
Stated Advantages
The microsclerotia are highly desiccation tolerant and storage stable after drying and application to seeds.
The liquid culture fermentation methods produce higher yields of microsclerotia and submerged conidia with improved storage viability compared to previous methods.
The microsclerotia-based compositions effectively control various plant pathogenic fungi and promote plant growth.
Production methods reduce fermentation times and overcome constraints of solid substrate fermentation, potentially lowering production costs and enabling scale-up.
Documented Applications
Use of Trichoderma microsclerotia compositions for controlling fungal plant diseases including Rhizoctonia, Sclerotinia, Sclerotiorum, Fusarium, Verticillium, Phytophthora, Castenea, Armillaria, Pythium, and Thielaviopsis.
Promotion of plant growth and health by application of Trichoderma microsclerotia compositions to soil, seeds, or plant surfaces.
Application of microsclerotia granules as a biocontrol agent in agricultural fields, orchards, greenhouses, gardens, lawns, ornamental plants, trees, and commercial or residential structures.
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