Produção de biomassa de Bacillus stratosphericus em meio nutricional contendo diferentes fontes de carbono

Abstract

The growing demand of the agricultural sector for techniques that assist in plant development, instigates research in the biotechnological field for research on improvement processes, and in a sustainable and economically viable way, plant growth promoting bacteria (BPCP), appear as an alternative, for excreting substances as siderophores, molecules capable of sequestering Fe and making it available in a form suitable for plant nutrition. For the development of this bioprocess, attention was first paid to the nutritional environment, particularly the carbon source, which is essential for the production of cells and bacterial nutrition. Bacteria of the genus Bacillus are traditionally optimized with dextrose, but for this work, the aim was to investigate the biomass and siderophores production by Bacillus stratosphericus by varying the carbon source with sucrose and inverted sucrose. Initially, the growth curve was analyzed by inoculating 1 µL of the microorganism in 50 mL of the standard liquid medium NYD (nutrient-yeast-dextrose), incubated in a rotary oven operating at 30 ºC, 150 rpm for 24 hours. The exponential phase was observed between 3 and 9 hours of fermentation, with a maximum concentration of 2.97 g L-1. For the fermentation times of 9 to 18 hours, a phase of slow decline was observed, reaching 2.35 g L-1 in 18 hours of fermentation. After that time, the decline was rapid, reaching 0.62 g L-1 in 21 hours. The time of 18 hours was selected to study the variations of carbon sources in the concentrations of 5 g L-1, 10 g L-1 and 15 g L-1, replacing dextrose in the traditional NYD medium. The results obtained showed that for sucrose, the concentration of 5 g L-1 was more efficient for biomass production (3.7 g L-1). As for the inverted sucrose, the concentration of 15 g L-1 led to 4.28 g L-1 of biomass, both sources had higher biomass yield than the traditional composition with dextrose, which at 18h of cultivation, had a production of 2.35 g L-1 of biomass. The production of siderophores by the microorganism did not present satisfactory results.