Conditions to optimize mass production of Metarhizium anisopliae (Metschn.) Sorokin 1883 in different substrates

Abstract

One of the best alternatives to reduce the amount of chemical insecticides released into the environment is biological agents. Metarhizium anisopliae (Metschn.) Sorokin 1883 (Hypocreales: Clavicipitaceae) is an entomopathogenic fungus with great potential as a biological pesticide to biologically control pests. However, the relatively high cost of the substrate needed for its mass production system increases product price and discourages its use. The objective of this study was to optimize the mass production conditions of M. anisopliae for use as a biological control agent using two solid substrates, new parboiled rice (NPR) and recycled parboiled rice (RPR). Conidial production was optimized by the response surface methodology (RSM). The effects of the temperature, time, and molasses variables and the interactions between them (conidia g -1 ) were determined. For the NPR substrate, it was determined that the significant variables were time and temperature, and the interactions were temperature × molasses and temperature × time. For the RPR substrate, the significant variables were temperature and time, and the interactions were time × molasses and temperature × time. Both substrates obtained the highest industrial yields at 25 °C for a period of 20 d. Given that the percentage of molasses was not critical for yields, it is recommended that it be set at 5% to reduce costs. Finally, it was possible to use the RPR substrate from the M. anisopliae produ9ction itself as an alternative to solid substrate; mean industrial performance (conidia g -1 ) was higher than values obtained with NPR and at a lower cost.

Characterization of a new strain ofMetarhizium novozealandicumwith potential to be developed as a biopesticide

“…Rice is the most often chosen substrate to produce conidia for formulation in biopesticides, because it has easily available sources of nutrients at high concentrations, large surface areas and maintains its physical structure during sterilisation and the fermentation process (Bhanu Prakash et al 2008 ). The maximum yield was obtained when AgR-F177 was grown for 20 days on rice (1.68 x 10 9 conidia/g), resulting in the same magnitude (10 9 conidia/g) to previous reports for other entomopathogenic fungi produced using SF on rice grains, such as M. anisopliae, B. bassiana, and Beauveria brongniartii (Nelson et al 1996 ; Sahayaraj and Namasivayam 2008 ; Barra-Bucarei et al 2016 ).…”

“…This is supported by the continuing increase in conidia production during the 20 days of fermentation, while only a non-significant increase was observed after day 10 using SSF. The relationship between conidia yield and available surface area has been demonstrated for conidia mass production of several fungi including B. bassiana (Xie et al 2012 ), M. anisopliae (Barra-Bucarei et al 2016 ) and Trichoderma harzianum (Mayo-Prieto et al 2020 ). Rice is the most often chosen substrate to produce conidia for formulation in biopesticides, because it has easily available sources of nutrients at high concentrations, large surface areas and maintains its physical structure during sterilisation and the fermentation process (Bhanu Prakash et al 2008 ).…”

Metarhizium robertsii protease and conidia production, response to heat stress and virulence against Aedes aegypti larvae

“…Thus, riboflavin supplementation was extremely important for optimization of fungal culture medium. The joint supplementation of riboflavin with sodium nitrate has shown to be efficient in inducing conidia production in the range of 10 10 conidia/mL, an amount considered optimal compared to other studies of production optimization of fungi of the genus Metarhizium (Loera-Corral et al 2016 ; Barra-Bucarei et al 2016 ; Prakash et al 2008 ).…”

“…Conidia production is a commonly performed analysis in media optimization work for entomopathogenic fungi production using response surface methodology (Loera-Corral et al 2016 ; Barra-Bucarei et al 2016 ; Prakash et al 2008 ; Bich et al 2018 ). This methodology is also used for optimization of media in solid fermentation for the production of chitinases and cellulases (Aita et al 2019 ).…”

“…The methodology used was an adaptation of that used by Dhar and Kaur ( 2010 ), Barra-Bucarei et al ( 2016 ) and Lopes ( 2016 ). For the experiment, nine groups were formed: two control groups, one positive and one negative, and seven treated groups.…”