Banca de DEFESA: RENATA ANDREIA DOS SANTOS

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
STUDENT : RENATA ANDREIA DOS SANTOS
DATE: 26/02/2025
TIME: 14:00
LOCAL: Google Meet
TITLE:

PRODUCTION OF PIGMENTS AND BIOSURFACTANT BY CO-CULTIVATION OF Serratia marcescens AND Tetradesmus obliquus

KEY WORDS:

Bacteria, Microalgae, Pigments, Co-culture, Biosurfactant.

PAGES: 185
BIG AREA: Outra
AREA: Multidisciplinar
SUBÁREA: Biotecnologia
SUMMARY:

Natural products such as microbial pigments and biosurfactants have attracted attention for being non-toxic, sustainable and renewable. However, the production of biopigments and biosurfactants is still limited due to low yield and high production costs. Serratia marcescens and Tetradesmus obliquus were investigated for the production of carotenoid, chlorophyll, prodigiosin and biosurfactant, in co-cultivation as a strategy to increase the productivity of pigments and biosurfactant. The production of these biomolecules was carried out in monoculture and co-cultivation using alternative media as a sustainable method in order to compare the cultivation mode. The monoculture of T. obliquus was carried out in standard BG 11 medium (Medium 1) and in BG 11 medium supplemented with wheat bran (5%) and post-fried soybean oil (OSPF) at 5% (Medium 2). Monoculture of S. marcescens was carried out in medium 2 and co-cultivation in medium 1 and 2, which were used to determine the kinetic parameters, cell concentration, maximum specific growth rate and maximum cell productivity. After 48h, the cell-free liquid was used to evaluate the surface tension and oil displacement area (ODA). From the best condition, the interfacial tension and emulsification index were analyzed. The biosurfactant was isolated by acid precipitation and subjected to preliminary characterization, stability and phytotoxicity tests and application in the removal of burnt engine oil from mollusk shells. At the end of the cultivation, the biomass was concentrated and the carotenoid pigments, chlorophyll and prodigiosin were extracted using different solvents (methanol, ethanol and acetone). After selecting the pigment extraction solvent, these were evaluated in relation to temperature (0, 10, 50, 70 and 100ºC), pH (2, 4, 6, 8, 10 and 12) and NaCl (5, 10, 15 and 20%) and phytotoxicity in cucumber (Cucumis sativus) and lettuce (Lactuca sativa) seeds. The microalgae T. obliquus in monoculture in the standard BG 11 medium showed a higher cell concentration (Xmax = 398 ± 3 104 cells/mL), with an Xmax value three times higher than the other cultivation conditions; specific growth rate (µmax = 0.131 d−1), maximum cell productivity (PX = 34.63 104 cells/mL/d) and carotenoid of 36 mg/g extracted with ethanol and chlorophyll 248 mg/g extracted with acetone. The bacterium S. marcescens showed greater growth in co-cultivation with T. obliquus in BG11, wheat bran and OSPF with Xmax (18 ± 1 104 CFU/mL) and a greater production of prodigiosin 760 mg/g with the ethanol solvent. It is worth noting that prodigiosin production was greater in co-cultivation than in monoculture. In addition to being stable at different values of temperature, pH and NaCl and non-toxic. The results demonstrated that co-cultivation presented better conditions for biodispersant production, with values of surface tension (26.6 mN/m), ODA (50.24 cm2), interfacial tension (1.0 mN/m) and emulsification index (96%). The biosurfactant yield was 1.75 g/L, and it presented anionic and lipopeptide nature, as well as stability at alkaline pH and in a wide range of temperature and salinity. In addition, it demonstrated to be non-toxic to cucumber and lettuce seeds and presented 100% efficiency in washing mollusk shells impregnated with burnt engine oil. Thus, the cocultivation of S. marcescens and T. obliquus using agroindustrial substrates represents an innovative and sustainable technology for the production of pigments and biodispersant with industrial application.

COMMITTEE MEMBERS:
Externo à Instituição - CLÁUDIO JOSÉ GALDINO DA SILVA JUNIOR - UFRPE
Externa à Instituição - DAYANA MONTERO RODRÍGUEZ - UNICAP
Interna - ***.451.344-** - JULIANA MOURA DE LUNA - UFPE
Presidente - RAQUEL PEDROSA BEZERRA
Externa à Instituição - RITA DE CASSIA FREIRE SOARES DA SILVA