Preparation of Aspergillus niger 426 naringinases for debittering citrus juice utilization of agro-industrial residues / Preparación de naringinasas de Aspergillus niger 426 para el desamargado de jugo de cítricos aprovechamiento de residuos agroindustriales

Naringin, considered as the main bitter component of grapefruit, requires the use of enzymes to reduce the level of this substance during juice processing. For this reason, it has been the focus of many studies. In this study, to increase the production of naringinase by Aspergillus niger cultivated in solid-state fermentation (SSF), a three-component simplex-centric mixing design along with a response surface methodology (RSM) was applied to generate statistical models and analyze the dataset. First, grapefruit peel, rice bran, and wheat bran were used for substrate selection for naringinase production and, finally, selected the best of the three inducers or their mixtures to remove the bitterness of grapefruit juice. Cultivation with 2.3 g of grapefruit peel, 2.5 g of rice bran, and 5.2 g of wheat bran and medium supplementation with a mixture of naringin, rutin, and hesperidin in the concentration of 2, 5, 4.5, and 3.0 g/L, respectively, resulted in a maximum activity of 28 U/mL. The results indicate that the sequencing procedure, which allowed the definition of an optimal mixture of components, is a new way for microorganisms to have a high naringinase yield, in particular by SSF, since our data showed a 96% increase in the production of naringinase. This dataset can help other researchers apply a mixing design to increase enzyme production.(AU)

Preparation of Aspergillus niger 426 naringinases for debittering citrus juice utilization of agro-industrial residues.

Naringin, considered as the main bitter component of grapefruit, requires the use of enzymes to reduce the level of this substance during juice processing. For this reason, it has been the focus of many studies. In this study, to increase the production of naringinase by Aspergillus niger cultivated in solid-state fermentation (SSF), a three-component simplex-centric mixing design along with a response surface methodology (RSM) was applied to generate statistical models and analyze the dataset. First, grapefruit peel, rice bran, and wheat bran were used for substrate selection for naringinase production and, finally, selected the best of the three inducers or their mixtures to remove the bitterness of grapefruit juice. Cultivation with 2.3 g of grapefruit peel, 2.5 g of rice bran, and 5.2 g of wheat bran and medium supplementation with a mixture of naringin, rutin, and hesperidin in the concentration of 2, 5, 4.5, and 3.0 g/L, respectively, resulted in a maximum activity of 28 U/mL. The results indicate that the sequencing procedure, which allowed the definition of an optimal mixture of components, is a new way for microorganisms to have a high naringinase yield, in particular by SSF, since our data showed a 96% increase in the production of naringinase. This dataset can help other researchers apply a mixing design to increase enzyme production.

Nisin resistance in Gram-positive bacteria and approaches to circumvent resistance for successful therapeutic use.

Antibiotic resistance among bacterial pathogens is one of the most worrying problems in health systems today. To solve this problem, bacteriocins from lactic acid bacteria, especially nisin, have been proposed as an alternative for controlling multidrug-resistant bacteria. Bacteriocins are antimicrobial peptides that have activity mainly against Gram-positive strains. Nisin is one of the most studied bacteriocins and is already approved for use in food preservation. Nisin is still not approved for human clinical use, but many in vitro studies have shown its therapeutic effectiveness, especially for the control of antibiotic-resistant strains. Results from in vitro studies show the emergence of nisin-resistant bacteria after exposure to nisin. Considering that nisin has shown promising results for clinical use, studies to elucidate nisin-resistant mechanisms and the development of approaches to circumvent nisin-resistance are important. Thus, the objectives of this review are to identify the Gram-positive bacterial strains that have shown resistance to nisin, describe their resistance mechanisms and propose ways to overcome the development of nisin-resistance for its successful clinical application.

Utilization of agroindustrial byproducts for the production of lipase by a new strain of Pseudomonas sp / Utilização de subprodutos agroindustriais para a produção de lipase por uma nova cepa de Pseudomonas sp

This study aimed to evaluate the production of lipases by a new strain of Pseudomonas sp. using fermentation medium containing byproducts of poultry meat or soybean oil industry. The results indicate that chicken fat and soybean gum induced 48.3 U/mL and 93.3 of lipase activity, respectively. However, the higher lipase production was obtained when the crude lecithin gum was used, archiving 272.6 U/ml of activity after 24 hours. The partial biochemical characterization of the enzyme showed that the optimum reaction conditions were pH 9.0 and 35 °C. The enzyme was stable at temperatures between 25 to 75 °C and at pH from 6 to 9. The enzyme also showed good stability in organic solvents, such as acetronitrile, hexane, ethanol and isopropanol. This study indicates that the byproducts tested are promising for the production of lipase and can contribute to the reduction of enzymatic production costs on a large scale, increase the value of these byproducts and reduce potential environmental impacts caused by its accumulation in nature.(AU)

Este estudo teve como objetivo avaliar a produção de lipases por uma nova cepa de Pseudomonas sp. utilizando meio de fermentação contendo subprodutos de industrialização de carne de frango e óleo de soja. Os resultados indicaram que a gordura de frango e a goma de soja induziram 48,3 U/mL e 93,3 U/ml de atividade lipásica, respectivamente. No entanto, a produção de lipase mais elevada foi obtida quando a goma de lecitina bruta foi utilizada, induzindo 272,6 U/ml de atividade após 24 horas. A caracterização bioquímica parcial da enzima mostrou que as condições de reação ótimas foram de pH 9,0 e 35 °C. A enzima foi estável nas temperaturas entre 25 a 75 °C e pH de 6 a 9. A enzima mostrou boa estabilidade em solventes orgânicos, tais como acetonitrila, hexano, etanol e isopropanol. Este estudo indicou que os subprodutos testados são promissores para a produção de lipase e podem contribuir para a redução dos custos de produção enzimática em larga escala, aumentar o valor desses subprodutos e reduzir potenciais impactos ambientais causados por sua acumulação na natureza.(AU)