Equipamentos de baixo custo para controle de qualidade de bioinsumos produzidos on farm

Abstract

Bioinputs are biological products capable of promoting enhanced growth, development, and response mechanisms in the metabolism of plants. Their use not only aims to reduce economic impacts but also seeks to mitigate the environmental effects associated with agricultural practices. When based on microorganisms, these bioinputs can be produced by specialized companies following rigorous quality standards, or alternatively, through local production on rural properties, a process known as "on-farm" bioinput production. However, this production is heterogeneous, ranging from highly technified facilities to rudimentary and improvised systems using resources such as drums and plastic boxes, due to the high costs associated with commercial bioreactors. Another bottleneck in "on-farm" bioinput production is the assessment of the quality of these bioinputs, which, when conducted, is often limited to imprecise phenotypic techniques, especially for prokaryotes. The use of DNA-based techniques, on the other hand, can be quite opportune for quality control of bioinputs due to their precision; however, the equipment needed to perform these analyses is costly. In this work, we investigated the feasibility of applying Open Science principles to the development of low-cost and open-access equipment capable of replicating the functionalities of commercial equipment as a way to facilitate the use of molecular methods for bioinput quality control. This includes the development of the necessary instrumentation to perform DNA extraction, DNA fragment amplification by PCR (thermocycler), and band analysis by agarose gel electrophoresis (electrophoresis power supply and gel box) using microcontrollers, low-cost electronic components, and 3D-printed parts. Using nitrogen-fixing nodular bacteria in legumes as a proof of concept, we developed a low- cost methodology that allowed the execution of barcode analysis with BOX-PCR to distinguish different strains, species, and genera of bacteria. For the thermocycler developed here, the adopted temperature control system showed good stability and an average absolute error of 0.015°C. This equipment successfully amplified DNA fragments through BOX-PCR. For the gel electrophoresis power supply and gel box, there was correct discrimination of band profiles, resulting in distinct profiles for different isolates. Although adaptations are needed to make the equipment more user- friendly, we demonstrated a viable approach for making these molecular techniques accessible to small laboratories. The project is freely available with an open license for the user community to make necessary adaptations.