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)

Cyanobacterial extract-mediated synthesis of silver nanoparticles and their application in ammonia sensing

Green route for silver nanoparticle synthesis has gained increasing attention. Cyanobacteria are one of the promising organisms to produce a number of secondary metabolites that are capable of reducing silver ions to small-sized silver nanoparticles. In the present study, we employed an aqueous extract of the cyanobacterium Haloleptolyngbya alcalis KR2005/106 isolated from a soda lake for biosynthesis of silver nanoparticles (AgNPs). The extract acted as a reducing agent for AgNPs synthesis and resulted formation of nanoparticles <50 nm in size. In this study, synthesis of AgNPs obtained only in the sample exposed to photosynthetically active radiation (PAR) while the synthesis of AgNPs was not observed in the samples kept in dark. The biogenic fabrication of AgNPs was carried out by optimizing several governing parameters such as concentration of the silver nitrate solution, pH, temperature, and amount of biomass. Results obtained through different analytical techniques revealed that cyanobacterial taxon H. alcalis isolated from saline-alkaline habitat is a potential candidate for biosynthesis of optimum-sized spherical AgNPs. Surface plasmon resonance (SPR) property of AgNPs was exploited for aqueous ammonia sensing and revealed that AgNPs synthesized using aqueous extract of cyanobacterium H. alcalis could be employed for colorimetric detection of dissolved ammonia for monitoring quality of water

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