COMPARATIVO ENTRE MODELOS DE REATORES NA PRODUÇÃO DE BIOINSUMOS “ONFARM”

Abstract

Brazilian agriculture is highly technified and globally relevant; however, it is affected by a wide range of pests, diseases, and weeds that limit and/or reduce productivity. In addition, agricultural production is often conducted on soils considered chemically poor, as is the case for most soils in the Cerrado biome. To overcome these limitations, external inputs produced industrially—commonly referred to as pesticides or crop protection products, soil amendments, and fertilizers—are widely adopted to manage these constraints. In recent years, these chemical inputs have been gradually replaced or associated with biological inputs, known as bioinputs, which may be industrially produced by specialized companies or produced directly by farmers on their own farms. This latter process is commonly referred to as on-farm production of bioinputs. On-farm production is particularly used for the multiplication of bacteria, especially species of the genus Bacillus, using fermentation tanks with control of aeration, foam production, and temperature. On-farm production has the advantage of reducing production costs and increasing adoption by farmers; however, it also involves certain risks. Researchers have suggested that on-farm multiplication conditions may be inefficient, resulting in low microbial multiplication and a high risk of contamination, particularly by bacteria pathogenic to humans. Therefore, the objective of this study was to evaluate the on-farm multiplication of "Bacillus subtilis" and "Bacillus pumilus" using two types of reactors under different conditions. Samples from these fermentations were collected and submitted for microbial quantification. The presence of contaminants was detected in both multiplication processes. The values obtained for "B. subtilis" ranged from 6.22 × 10⁸ to 9.0 × 10⁹ CFU mL⁻¹, while those for "B. pumilus" ranged from 1 × 10⁶ to 1.3 × 10¹⁰ CFU mL⁻¹, depending on the condition evaluated. No identification of the contaminants present in these fermentations was performed. The results suggest that the microbial concentrations obtained are suitable for field application, provided that environmental conditions favorable for inoculum performance are respected. However, it should be noted that the detected contaminations were not investigated and may represent a risk to individuals handling this material. Quality control in the production of bioinputs, particularly those based on microorganisms, must be conducted rigorously to prevent contamination by pathogenic agents or failure in the multiplication of the desired species, which could ultimately result in agriculture losses.