Optimization of xanthan gum production by demerara sugar using response surface methodology

Xanthan gum (XG) production using three Xanthomonas sp. strains (290, 472, and S6) was evaluated by applying a 23 full factorial central composite design response to study the interactive effects of the fermentation medium component concentrations as parameters to determine the efficiency of the gum production in batch experiments. The experimental variables were the carbon source (demerara sugar or sucrose), potassium phosphate dibasic, and magnesium sulfate. Experimental results showed the K2HPO4 concentration as the important parameter for XG production by using Xanthomonas axonopodis pv. manihotis IBSBF 290 and X. campestris pv. campestris IBSBF 472, while for the Xanthomonas sp. S6 strain, the MgSO4∙7H2O concentration was the determining factor in XG production using demerara sugar or sucrose as a carbon source. The strains of Xanthomonas 472 and S6, using demerara sugar and higher concentrations of salts, exhibited a higher yield of XG (36 and 32%) than when using sucrose and the same concentration of salts. The experimental outcomes highlighted demerara sugar as a suitable and efficient alternative carbon and micronutrient source for XG production. Despite the bacterial strain influence, the medium composition is crucial for this fermentation process. Therefore, the evaluated salts are important factors for XG production, and the demerara sugar can partially replace this mineral salt requirement as indicated by the face-centered composite experimental design due to its chemical composition. Overall, demerara sugar provides promising properties for XG production.The authors acknowledge the financial assistance from the Brazilian research funding agencies including the Co-ordination for the Improvement of Higher Education Personnel (CAPES) under Finance Code 001, a Brazilian foundation within the Ministry of Education (MEC); the National Council for Scientific and Technological Development (CNPq), a Brazilian foundation associated to the Ministry of Science, Technology, and Innovations (MCTI); the Foundation of Support to Research and Technological Innovation of the State of Sergipe (FAPITEC/SE); and the Regional Co-operative of Agrarian Reform Settlers of Sergipe’s Semi-Arid. The authors acknowledge the Foundation for Science and Technology (FCT, Portugal) for the financial support to the CISAS UIDB/05937/2020 and UIDP/05937/2020, including the postdoc grant and the contract of the two authors.info:eu-repo/semantics/publishedVersio

Use of Agro-Industrial Waste for Biosurfactant Production: A Comparative Study of Hemicellulosic Liquors from Corncobs and Sunflower Stalks

Biosurfactants have attracted considerable attention because of their lower toxicity, biocompatibility, and effectiveness over chemical surfactants. The use of renewable sources and the concept of sustainable production for such biomolecules supports the increased demand for eco-friendly products. Herein, the present study investigated corncobs (CC) and sunflower stalks (SS) as substitutes for conventional substrates in submerged fermentation with B. subtilis. The agro-industrial residues were submitted to an alkaline pretreatment to obtain hydrolysates rich in hemicelluloses, whose concentrations were determined at 48.8% and 65.7% for corncob and sunflower stalk liquors, respectively. The influence of different concentrations of glucose (0, 2.5, and 5%) and liquor (0, 20%, and 40%) were evaluated according to cell concentration, surface tension reduction rate (STRR), and emulsification index (EI24). Biosurfactants obtained with the hemicellulose liquor of sunflower stalk showed the highest cell concentration (4.57 g/L) and STRR (58.07%), whereas the maximum values of EI24 (56.90% in hexane, 65.63% in toluene, and 64.86% in kerosene) were achieved by using corncob liquor. All top results were observed at 2.5% glucose, 20% liquor (CC or SS), and 1% mineral salts. Notably, excess glucose or liquor (CC or SS) negatively affected cell growth and biosurfactant performance. The results indicated the potential of corncobs and sunflower stalks as low-cost substrates to produce a high added-value biosurfactant with promising tensoative and emulsifying properties

Obtenção de exopolissacarídeos tipo goma xantana por uso de licor obtido do pré-tratamento alcalino de sabugo de milho

CARTA PATENTE Nº BR 102014015027-7This Invention Patent (IP) concerns the use of the recipe liquid from the alkaline pre-treatment of agricultural residues or agro-industrial products, also known as liqueur, more specifically from cob corn, repaired by different compounds among which can be highlighted xyloses, arabinoses, glucose, cellobiose, hemicelluloses, lignin and micronutrients, as a culture medium, therefore being considered as an important source of carbon, micro and macronutrients to be used in the process fermentative, preferably using bacteria of the genus Xanthomonas sp., in the production of xanthan gum, which has wide application in the industry chemical, petrochemical, pharmaceutical and food industries.info:eu-repo/semantics/publishedVersio

Rare predicted loss-of-function variants of type I IFN immunity genes are associated with life-threatening COVID-19

BackgroundWe previously reported that impaired type I IFN activity, due to inborn errors of TLR3- and TLR7-dependent type I interferon (IFN) immunity or to autoantibodies against type I IFN, account for 15-20% of cases of life-threatening COVID-19 in unvaccinated patients. Therefore, the determinants of life-threatening COVID-19 remain to be identified in similar to 80% of cases.MethodsWe report here a genome-wide rare variant burden association analysis in 3269 unvaccinated patients with life-threatening COVID-19, and 1373 unvaccinated SARS-CoV-2-infected individuals without pneumonia. Among the 928 patients tested for autoantibodies against type I IFN, a quarter (234) were positive and were excluded.ResultsNo gene reached genome-wide significance. Under a recessive model, the most significant gene with at-risk variants was TLR7, with an OR of 27.68 (95%CI 1.5-528.7, P=1.1x10(-4)) for biochemically loss-of-function (bLOF) variants. We replicated the enrichment in rare predicted LOF (pLOF) variants at 13 influenza susceptibility loci involved in TLR3-dependent type I IFN immunity (OR=3.70[95%CI 1.3-8.2], P=2.1x10(-4)). This enrichment was further strengthened by (1) adding the recently reported TYK2 and TLR7 COVID-19 loci, particularly under a recessive model (OR=19.65[95%CI 2.1-2635.4], P=3.4x10(-3)), and (2) considering as pLOF branchpoint variants with potentially strong impacts on splicing among the 15 loci (OR=4.40[9%CI 2.3-8.4], P=7.7x10(-8)). Finally, the patients with pLOF/bLOF variants at these 15 loci were significantly younger (mean age [SD]=43.3 [20.3] years) than the other patients (56.0 [17.3] years; P=1.68x10(-5)).ConclusionsRare variants of TLR3- and TLR7-dependent type I IFN immunity genes can underlie life-threatening COVID-19, particularly with recessive inheritance, in patients under 60 years old