Otimização do cultivo de Cunninghamella elegans para a produção de biomassa, quitina, quitosana e biossurfactante em meio de resíduo agroindustriail

Abstract

The advancement of technological, agricultural, and urban sectors increasingly requires the use of polymers for their activities to take place. The search for natural polymers emerges as a demand for these sectors, since conventional ones can have a high production cost, in addition to causing environmental damage. The production of these can be done through the cultivation of microorganisms, which in their structure have important biopolymers such as chitin and chitosan. Therefore, the objective of this work was to analyze the best cultivation conditions for C. Elegans DSM1255, to produce biomass, chitin, chitosan and biosurfactant. As a methodology, the best physicochemical cultivation conditions were determined using a Plackett-Burman planning with 7 variables (concentration of glucose, nitrogen, asparagine, spores, pH, temperature, and duration of cultivation). Followed by a Box-Behnken design to optimize glucose and peptone amounts. With the optimization, the microorganism was grown in corn steep liquor medium supplemented with glucose. The masses obtained in all experiments were used for the extraction of chitin and chitosan by the chemical method NaOH 1M 30:1v/m, at 121 °C for 15 minutes, CH₃COOH 2% 30:1 v/m, at 100 °C for 15 minutes and chitin with the NADES choline chloride and lactic acid at 80 ºC for 3 h with the powder mass. The biosurfactant was isolated from the broth resulting from the cultivation of cornstarch with a chloroform: methanol solution and the emulsification index was analyzed after 24 h of mixing the culture liquid with soybean oil, through the ratio of the height of the emulsifier layer with the total height, multiplied by 100. Statistical analysis was performed using the STATISTICA 6.0 software. As a result, the highest mass found in the PlackettBurman design was 11.93 g/L and the parameters glucose, peptone, asparagine, and temperature were considered relevant for the increment of biomass. In the Box-Behnken concentration of 40 g/L of glucose and 27.5 g/L of peptone there would be a greater production of biomass. With all the conditions optimized, the cultivation in corn steep liquor medium obtained a yield of 13.62 g/L of dry mass. The production of chitin and chitosan by chemical method showed lower results than those found in the literature, with 66.66 mg chitin/g of mass and 12.66 mg of chitosan/g of mass. Extraction with NADES obtained better chitin yields with 973 mg/g, a result superior to that found in the literature. The biosurfactant yield of 2.64 g/L was close to that reported in the literature, but the soybean oil emulsion index was low (22.78%). Therefore, the present work established the best cultivation conditions for C. Elegans DSM 1255, resulting in the highest biomass yield reported só far for this strain. The extraction of chitin with NADES showed great efficiency, but it still needs to be proven that the material is composed only of chitin. The biosurfactant showed good performance, but with a low emulsion index, requiring tests on other materials to test the stability of the emulsion.