Production of conidia of the entomopathogenic fungus Metarhizium anisopliae ICB 425 in a tray bioreactor

A Novel Model of Pathogenesis of Metarhizium anisopliae Propagules through the Midguts of Aedes aegypti Larvae

We assessed the effect of the entomopathogenic fungus Metarhizium anisopliae against Aedes aegypti. Conidia of M. anisopliae strains CG 489, CG 153, and IBCB 481 were grown in Adamek medium under different conditions to improve blastospore production. Mosquito larvae were exposed to blastospores or conidia of the three fungal strains at 1 × 10⁷ propagules mL^-1. M. anisopliae IBCB 481 and CG 153 reduced larval survival by 100%, whereas CG 489 decreased survival by about 50%. Blastospores of M. anisopliae IBCB 481 had better results in lowering larval survival. M. anisopliae CG 489 and CG 153 reduced larval survival similarly. For histopathology (HP) and scanning electron microscopy (SEM), larvae were exposed to M. anisopliae CG 153 for 24 h or 48 h. SEM confirmed the presence of fungi in the digestive tract, while HP confirmed that propagules reached the hemocoel via the midgut, damaged the peritrophic matrix, caused rupture and atrophy of the intestinal mucosa, caused cytoplasmic disorganization of the enterocytes, and degraded the brush border. Furthermore, we report for the first time the potential of M. anisopliae IBCB 481 to kill Ae. aegypti larvae and methods to improve the production of blastospores.

Current developments in the resistance, quality, and production of entomopathogenic fungi

There is a worldwide concern to achieve food security with a sustainable approach, including the generation and implementation of techniques for the production of high-quality chemical-free crops. This food revolution has promoted the development and consolidation of programmes for integrated pest management. Some of those programmes include the use of diverse organisms (biological control agents) to suppress populations of pests potentially harmful to the crops. Among these biological control agents are entomopathogenic fungi that are highly effective in suppressing a diversity of insects and have, therefore, been produced and marketed throughout the world. However, the bottleneck for applying entomopathogenic fungi is the production of propagules (blastospores and conidia) with resistance to environment conditions and abiotic factors, maintaining high quality in terms of virulence. Therefore, this manuscript presents recent studies related to increasing resistance and quality using different bioreactors to produce conidia. The above presents a global panorama related to current developments that contribute to improving the resistance, quality, and production of entomopathogenic fungal propagules.

Improving enzyme production by solid-state cultivation in packed-bed bioreactors by changing bed porosity and airflow distribution

Enzymes production by solid-state cultivation in packed-bed bioreactor needs to be improved by mathematical modeling and also by experimentation. In this work, a mixture of sugarcane bagasse and wheat bran was used for the growth of the fungus Myceliophthora thermophila I-1D3b, able to secrete endoglucanase and xylanase, enzymes of interest in the second-generation ethanol production. Bench and pilot-scale bioreactors were used for the experiments, while critical parameters as bed porosity and airflow distribution were evaluated. Results showed enzymes with higher activities for the most porous medium, even though the less substrate amount to be cultivated. For the pilot-scale bioreactor, only the most porous medium was evaluated using different airflow distribution techniques. Using an inner tube for air supply resulted in more homogeneous enzyme production, with higher activities. The results here presented will be helpful for the scale-up of this class of bioreactor into industrial apparatuses.