Cinética de crescimento de Bacillus subtilis ATCC 6633 e atividades proteolítica e celulolítica em meios de cultura formulados a partir do hidrolisado ácido da macroalga vermelha Solieria filiformis

Abstract

In recent decades, the global challenges induced by climate and environmental changes have shown the need to develop environmentally friendly and chemical means of production. In this context, algal biomass, a renewable natural resource, cultivated in the sea and with great atmospheric carbon fixation, has aroused much research interest in recent years for energy generation and industrial inputs. The present work aims to use the thermal-acid hydrolyzate from the biomass of S. filiformis as a medium rich in carbohydrates for the production of Bacillus subtilis enzymes. Acid hydrolysis of algal biomass was performed at 121°C, 0.5 M H2SO4 for 20 min. After filtration and pH adjustment of the filtrate, the hydrolyzate was used to compose two fermentation media: undiluted hydrolyzate (HID) and diluted hydrolyzate (H1:1) with 0.15 M NaCl in a 1:1 ratio (v/v). The control medium was a nutrient broth containing glucose (CNglic). The inoculum was prepared in CNglic for 24 h in mandatory at 150 rpm and under incubation at 37 ºC. The fermentations were carried out in duplicates at 37 ºC under orbital of 150 rpm for 72 h. The plate viable cell count was performed. The enzymatic extract was obtained from centrifugation at 9,900 xg for 10 min of the media after fermentation. Proteolytic and cellulolytic activities were measured. The HID medium showed the best growth of B. subtilis, with a maximum cell concentration of 4.17 x 1013 CFU/mL at 48 h of fermentation. The H1:1, HID and CNglic media demonstrated, respectively, maximum activity of proteolytic enzymes of 4.90 U/mL, 28.05 U/mL and 45.20 U/mL in the culture times of 58h, 24h and 48h, and maximum activity of cellulolytic enzymes of 0,017 U/mL, 0,050 U/mL and 0,019 U/mL at 72h, 72h and 48h, respectively. The H1:1 and HID media are known to be promising media for fermentation processes and for the production of proteolytic and cellulolytic enzymes from B. subtilis.