Artificial lichens and the integration of high value-added products into a biorefinery

Author(s)

Savienne Maria Fiorentini Elerbrock Zorn

• Document type: Doctoral Thesis
• Press: Lorena.
• Institution: Universidade de São Paulo (USP). Escola de Engenharia de Lorena (EEL/ASDI)
• Defense date: 2023-02-10

Examining board members

Messias Borges Silva; Ana Karine Furtado de Carvalho; Carla Cristina Almeida Loures; Patrícia Caroline Molgero Da Rós

• Advisor: Messias Borges Silva

Abstract

Microbial consortia represent a clean alternative to cell harvesting, as well as the generation of high value-added bioproducts. In this sense, the present work evaluated the formation of artificial lichens with two microalgae species (Chlorella vulgaris BMAK 007 and Scenedesmus obliquus CCCMA-UFSCar604) and a filamentous fungus (Mucor circinelloides f. griseo-cyanus URM 4182). In the first stage of the research, four distinct lichenization strategies were evaluated between the species C. vulgaris, considered a model microalgae, and the filamentous fungus, in co-cultures carried out in an orbital shaker. The best condition resulted in an artificial lichen composed of 79% of microalgae biomass and cell recovery efficiency of 99.5%. In the second stage, the best result strategy was reapplied for the species S. obliquus and the filamentous fungus. The effect of supplementing the microalgae culture medium with sugarcane molasses (SM) was studied on the increase in biomass and lipids. Results from cultures with SMsupplemented medium showed that microalgae biomass and its microbial consortium doubled compared to cultures without supplementation and the accumulation of lipids in the biomass increased by 1.5 times. Furthermore, the cell recovery efficiency remained at 99.7%, with a contribution of 80% of algae biomass in the lichen composition, lipid content of the algae:fungus consortium equal to 38.2% by weight, and a balanced fatty acids composition (52.7% saturated and monounsaturated fatty acids, 47.4% polyunsaturated fatty acids). In the final stage of the research, co-cultures were carried out on an orbital shaker table, using larger volumes of culture medium, as well as a larger amount of cells and fungal mycelia. The lichenization experiments in this equipment had the main objective, to produce a greater amount of biomass, enabling its characterization and use for the synthesis of bioproducts. The concentrations obtained in dry lichen biomass were, on average, 2.71 g/L, twice as compared to the biomass grown in an orbital shaker (1.27 g/L). The lipid content of the formed lichens was 32.0 ± 0.4%, and the average contribution of algal biomass in the lichens was 61 ± 2.1%. Lichen biomass was characterized by scanning electron microscope (SEM) and spectroscopy in the infrared region (ATR-FTIR). The oleaginous biomass was applied for the synthesis of biolubricant and biodiesel: for the biolubricant, simulated fusel oil was used as acyl receptor; for biodiesel, ethanol as a solvent and reagent. The respective results were obtained, in ester contents: 96.8% for biolubricant and 98.8% for biodiesel. Based on the fatty acid composition of the oil extracted from lichenized biomass, the following properties for biodiesel were estimated: cetane number, iodine number, oxidation stability, specific gravity, and kinematic viscosity. The results demonstrated that artificial lichens can be an efficient alternative for bioremediation and low-cost cell harvesting, in addition providing an oilseed biomass for various industrial applications. Artificial lichens contain a very interesting biotechnological potential to be explored in biorefineries. (AU)

• FAPESP's process: 18/01386-3 - Artificial lichens and the integration of products with high added value to a biorefinery
• Grantee: Savienne Maria Fiorentini Elerbrock Zorn
• Support Opportunities: Scholarships in Brazil - Doctorate