Cultivo simultâneo de Paraburkholderia tropica e Gluconacetobacter diazotrophicus para a produção de inoculante

Abstract

A mixed inoculant was proposed for sugarcane in 2008 based on long-term studies of inoculation and performance of diazotrophic bacteria in promoting plant growth. However, this product is not available to producers probably because of the difficulty of developing bioprocesses for the industrial multiplication of microorganisms. Parameters associated with growth were tested to establish maximal cell biomass production by simultaneous cultivation of two strains comprising the mixed inoculant, Paraburkholderia tropica (strain BR 11366) and Gluconacetobacter diazotrophicus (BR 11281) for the production of commercial inoculants. It was established through growth curves in orbital shaker that the optimum growth temperature for the strains is 32 °C, with maximum growth specific velocity µmax = 0.77 h-1 and µmax = 0.87 h-1 for BR11281 and BR11366 respectively. The strains have distinct growth efficiency under the evaluated conditions. Even so, there was no inhibition of growth between the strains, being possible to cultivate them simultaneously. The maximum production of DNA copy number mL-1 in simultaneous culture was observed in a bench bioreactor, with aeration of 4 L min-1 and temperature at 32 °C, reaching 2.02·109 DNA copy number mL- 1 of BR11281 and 5.05·1010 DNA copy number mL-1 of BR11366.