This work aimed to obtain and characterize bacterial cellulose (BC) membranes obtained by cultivating Komagataeibacter hansenii ATCC 23769 using mannitol, glucose, fructose, lactose, glycerol, inulin, and sucrose as carbon sources, and corn steep liquor and Prodex Lac® as alternative sources of nitrogen. The formation of the BC´s gelatinous membrane was monitored for 12 days under static conditions and a temperature of 30 ºC. After purification, the membranes were dried and characterized by thermogravimetric analysis (TGA), Fourier-transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). The highest BC concentrations were found in the culture medium containing Prodex Lac® as the source of nitrogen. Among sugars, fructose and mannitol presented the best results. TGA analyzes indicate that all membranes have similar thermal behavior. The FTIR results show that the chemically synthesized membranes are equivalent to the structures cited in the literature. The micrographs obtained by SEM showed that the medium might influence BC´s morphology, but in general, all presented nanofibers, an essential feature in the membrane. Thus, the BC membranes synthesized in this study proved that the BC production using low-cost alternative means is feasible. The material obtained meets the expected thermal, physical, and chemical properties.
A new generation of functional healing membranes has been researched to avoid infection and improve wound healing, combining wound moisture maintenance properties, exudate removal, antimicrobial activity, and the absence of side effects. Thus, this work aims to synthesize wound dressing membranes of bacterial cellulose (BC) incorporated with different plant extracts with antimicrobial properties. The BC membranes are synthesized by the bacterium Komagataeibacter hansenii and are associated with the extracts through the ex situ incorporation technique. The barbatimão extract presents the most significant total phenolic content and antimicrobial activity of the extracts researched. The determination of tannins and flavonoids confirms the extracts’ incorporation into the samples’ structure. The thermogravimetric analysis of the membranes incorporated with the extracts shows a reduction in the thermal stability relative to BC. The results show a good final extract for developing healing membranes with antimicrobial properties.
Lactic acid (LA) is one of the most important organic acids, with a wide range of industrial and biotechnological applications and can be produced by chemical synthesis and microbial culture. However, the biotech pathway is generally preferred because it provides an optically pure product. In this context, the purpose of this work was to evaluate LA biosynthesis by Lactobacillus amylovorus using molasses as carbon source (CS) and corn steep liquor as nitrogen source (NS) in a central composite rotatable design (CCRD) varying the concentration CS and NS, as well as to validate the model. The method for microbial culture followed an experimental design of the CCRD type, conducted without agitation, at 37ºC in Erlenmeyer flask, with pH in spontaneous evolution. The results showed that, using molasses and corn steep liquor as alternative sources, LA production ranged from 2.8 to 4.6 g/L, respectively, with the most favourable condition being 40.0 g of molasses and 250 g of corn steep liquor. It was possible, from the experimental design, to ascertain the selection of the best conditions for the microbial culture, demonstrating the feasibility of replacing CS and NS by agro-industrial waste, thus reducing the cost of producing LA.
Lactic acid (LA) is one of the most important organic acids, with a wide range of industrial and biotechnological applications and can be produced by chemical synthesis and microbial culture. However, the biotech pathway is generally preferred because it provides an optically pure product. In this context, the purpose of this work was to evaluate LA biosynthesis by Lactobacillus amylovorus using molasses as carbon source (CS) and corn steep liquor as nitrogen source (NS) in a central composite rotatable design (CCRD) varying the concentration CS and NS, as well as to validate the model. The method for microbial culture followed an experimental design of the CCRD type, conducted without agitation, at 37ºC in Erlenmeyer flask, with pH in spontaneous evolution. The results showed that, using molasses and corn steep liquor as alternative sources, LA production ranged from 2.8 to 4.6 g/L, respectively, with the most favourable condition being 40.0 g of molasses and 250 g of corn steep liquor. It was possible, from the experimental design, to ascertain the selection of the best conditions for the microbial culture, demonstrating the feasibility of replacing CS and NS by agro-industrial waste, thus reducing the cost of producing LA.
A área rural de Joinville tem como característica principal a atividade de agricultores de pequeno e médio porte, juntamente com o turismo rural. A Estrada Bonita, localizada na Área de Proteção Ambiental Serra Dona Francisca, tem vários estabelecimentos relacionados ao turismo rural, tais como hotéis, trilhas e restaurantes. O Rio Pirabeiraba situa-se ao lado dessa estrada e recebe muitos visitantes e banhistas. Portanto, é importante monitorar o rio para saber se essas atividades adjacentes estão impactando o rio. O monitoramento foi realizado por meio da análise de parâmetros físico-químicos, microbiológicos e ecotoxicológicos em dois pontos distintos (A e B) do rio durante 12 meses, para verificar possíveis alterações nas características de acordo com a região e a sazonalidade. Para verificar se há despejo de efluentes domésticos, fez-se teste para detectar a presença de coliformes termotolerantes. Para verificar se há toxicidade ecológica, foi utilizado o microcrustáceo bioindicador Daphnia magna. Ambos os pontos se mostraram impactados e com alterações no ciclo de vida de Daphnia magna. A análise microbiológica mostrou que o ponto B tem mais incidência de coliformes em todos os meses de coleta, sendo o número superior ao estabelecido pela Resolução Conama n.º 357.
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