Assessment of artificial neural networks to predict red colorant production by Talaromyces amestolkiae.

Consumer choice is typically influenced by color, leading to an increase in the use of artificial colorants by industry. However, several artificial colorants have been banned due to their harmful effects on human health and the environment, leading to increased interest in colorants from natural sources. Natural colorants can be found in plants, insects, and microorganisms. The importance of evaluating the technical and cost feasibility for the production of natural colorants are important factors for the replacement of artificial counterpart. Therefore, it is highly beneficial to predict the productivity of microbial colorants. The use of statistical methods that generate polynomial models through multiple regressions can provide information of interest about a bioprocess. However, modeling and control of biological processes require complex systems models, because they are nonlinear and non-deterministic systems. In this regard, artificial neural networks are suitable for estimating bioprocess variables with systems modeling. In this work, two different strategies were developed to predict the production of red colorants by Talaromyces amestolkiae, namely simulation by artificial neural networks (ANN) and response surface methodology (RSM). The results showed that the colorant concentration predicted by ANN is closer to the experimental data than that predicted by polynomial models fitted by multiple regression. Thus, this work suggests that the use of ANN can identify the initial conditions of the culture parameters that have the greatest influence on colorant production and can be a tool to be employed to improve the production of biotechnological products, such as microbial colorants.

Anthraquinone encapsulation into polymeric nanocapsules as a new drug from biotechnological origin designed for photodynamic therapy.

Photodynamic therapy has been applied for the treatment of many diseases, especially skin diseases. However, poor aqueous solubility and toxicity of some photosensitizer drugs are the main disadvantages for their direct clinical applications. Thus, biotechnology and nanotechnology are important tools in the development of new ways of obtaining photoactive compounds that are biocompatible. We investigated the potential of a new nanostructured photosensitizer, an anthraquinone derivative produced by biotechnological process; then we associated nanotechnology to obtain a nanostructured anthraquinone active molecule. For this, it was prepared a classical nanocapsule formulations containing poly(lactide-co-glycolide) (PLGA) coating for encapsulation of anthraquinone derivative. These formulations were characterized by their physicochemical, morphological, photophysical properties, and stability. We performed in vitro biocompatibility and photodynamic activity assays of free and nanostructured anthraquinone. Nanocapsule formulations containing anthraquinone derivative showed a nanometric profile with particle size around 250 nm, negative zeta potential around -30 mV, and partially monodisperse. Besides that, characteristic spherical morphology of nanocapsules and homogeneous particle surface were observed by AFM analyses. The in vitro biocompatibility assay showed absence of cytotoxicity for all tested RD/NC concentrations and also for unloaded/NC in NIH3T3 cells. In vitro photoactivation assay using NIH3T3 cells showed that nanocapsules promoted greater drug uptake by NIH3T3 cells, around of 87%, of cell death compared to free drug showed around 48% of cell death. The anthraquinone derivative showed potential for use in PDT. Besides the association with nanocapsules improved cell uptake of photosensitizer resulting in increased cell death compared to free anthraquinone.

Extraction and Characterization of Hemicellulose from Eucalyptus By-product: Assessment of Enzymatic Hydrolysis to Produce Xylooligosaccharides.

Eucalyptus wood is the primary source of fibers to produce paper and cellulose in South American countries. The major by-product generated in the cellulose industry is sawdust derived from chip wood production, which is designated as Eucalyptus by-product (EB). The xylooligosaccharides (XOS) are xylose-based oligomers with proven effects over maintenance and stimulation of beneficial human gut bacteria. This study reported the EB extraction and characterization along with an assessment of hemicellulose hydrolysis using commercial xylanases to produce XOS. Hemicellulose derived from extracted and NaClO2 pretreated (HEEBPT) presented xylan content of 55%, which was similar to 58.5% found in commercial Birchwood hemicellulose (CBH). The enzymatic hydrolysis of HEEBPT and CBH presented 30% as maximum conversion of xylan into XOS without significant difference among the enzymatic extracts evaluated. The XOS production from EB was proven as a technically feasible alternative to recover a value-added product from hemicellulosic fraction generated in the cellulose industry. However, lignin removal with NaClO2 from EB affects the feasibility of an industrial process because they generate toxic compounds in the pretreatment step. Thus, further studies with alternative reagents, such as ionic liquids, are required to asses selectively lignin removal from EB. Graphical Abstract.

Bioreactor aeration conditions modulate growth and antigen expression during Erysipelothrix rhusiopathiae cultivation.

Erysipelothrix rhusiopathiae, the causative agent of swine erysipelas, was cultivated in a 5-L stirred and aerated bioreactor under different dissolved oxygen tensions (0%, 5%, and 30% of saturation) for evaluation of the influence of oxygen on cell growth as well as on the production of the main antigenic component of the vaccine against erysipelas, a 64-69 kDa protein (SpaA). The microorganism presented different growth profiles for different aeration conditions. However, at the end of the batch cultivations, similar cell concentrations were obtained under the studied conditions. In order to maximize biomass titers and antigen production, the microorganism was cultivated in fed-batch operation mode under aerobic conditions. Under this condition, there was a fivefold increase in biomass production in comparison to the results attained in batch cultivations. To follow up antigen expression, samples collected during batch cultivations were concentrated and treated with choline for antigen extraction. Antigen expression was then assessed by sodium dodecyl sulfate polyacrylamide gel electrophoresis and by murine immunization tests. It was observed a direct influence of oxygen availability upon antigen expression, which is favored in the presence of oxygen. Analysis of the samples collected throughout the fed-batch process also revealed that antigen production is growth associated.