| Congresso Brasileiro de Microbiologia 2023 | Resumo: 856-2 | ||||
Resumo:The search for low-cost, renewable and ecologically safe substrates for the formulation of bioproducts is a key factor for the implementation of sustainable technologies. In this sense, the manufacture of new biosurfactants, which are amphiphilic molecules, having surface-active, emulsifying, dispersing properties, among others, aims at using residues and agro-industrial by-products as raw material. Thus, the present study aimed to use the filamentous fungus Mucor circinelloides UCP 0017 to produce a biosurfactant from corn steep liquor and residual soybean oil from frying as a sustainable strategy and to evaluate its toxicity for future environmentally safe applications. For the production of the biosurfactant, a previously established production medium was used, consisting of corn steep liquor (6%) and residual frying oil (6%), plus 5% of a suspension of 107 spores/mL of the isolate of M. circinelloides UCP 0017. A submerged fermentation was carried out at 28 °C, pH 6.5 for 96 h under orbital stirring at 150 rpm. After this period, the cell-free metabolic liquid was used to determine the surface tension (ST) and the emulsification index (E24) in soybean oil, motor oil, corn oil and burnt motor oil. Then, a critical micellar dilution (CMD) of up to 1% was performed to determine the minimum amount of biosurfactant used to maximally reduce ST. For the phytotoxicity assays, the chemical surfactant SDS (sodium dodecyl sulfate) was used as a positive control and water as a negative control. Seeds of Eruca vesicaria ssp. sativa and Solanum lycopersicum var. Cerasiforme were used as bioindicators of toxicity, and then the germination index (GI) of the seeds was calculated. The results obtained, with the best reduction of the ST of the medium to 31.0 mN/m and the E24 to 51.66% of the emulsion with engine oil, confirmed the presence of surfactants produced by M. circinelloides in the medium. The best ST value was obtained in the 10% DMC with 30.5 mN/m. With the concentrated biosurfactant, GI of 10.27% and 66.40% were obtained for E. vesicaria ssp. sativa and S. lycopersicum var. Cerasiform, respectively. On the other hand, the 10% diluted biosurfactant showed a GI of 167.82% and 168% of E. vesicaria ssp. sativa and S. lycopersicum var. Cerasiform, respectively. Thus, the phytotoxicity revealed that both the concentrated and diluted biosurfactant at 10% did not show toxicity to the seeds of S. lycopersicum var. Cerasiform tested. The results obtained indicated that the biosurfactant produced by M. circinelloides is ecologically compatible when in contact with the environment. Thus, the biomolecule is considered promising for future environmental applicability like, for example, in the bioremediation of sites contaminated by hydrocarbons. Palavras-chave: superficial tension, toxicity, germination index, agroindustrial by-products Agência de fomento:Fundação Antônio dos Santos Abranches (FASA), Fundação de Amparo à Ciência e Tecnologia do Estado de Pernambuco (FACEPE) e Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) | |||||