Antifungal Activity Enhancement of Cell-Free Streptomyces griseus Extract Obtained by Fermentation with Magnetic Manganese Ferrite Nanoparticles.

The present study aims to obtain manganese ferrite nanoparticles functionalized with chitosan (C-MNP) or ethylenediamine (E-MNP) by coprecipitation and polyol one-step methods, characterize their interaction with S. griseus demonstrating cell immobilization, and evaluate the antimicrobial activity of the free cell extracts obtained from immobilized S. griseus fermentation in the presence of different concentrations of MNP. The adsorption isotherms were analyzed mathematically using Langmuir and Freundlich models. The highest coefficient of determination (R2) for the S. griseus cell adsorption isotherm with C-MNP was observed with a linear function of the Langmuir model. The adsorption isotherm of S. griseus cells with E-MNP was better fitted to the Freundlich model. Cell immobilization by adsorption on magnetic nanoparticles was demonstrated in both cases. Different concentrations of C-MNP and E-MNP were used in fermentations to prepare cell-free extracts with antifungal activity. The best results were obtained with E-MNP, with a 91.5% inhibition of radial fungal growth. Magnetic nanoparticles offer potential applications in different fields and easy biomass separation.

Recent trends and technological development in plasma as an emerging and promising technology for food biosystems.

The rising need for wholesome, fresh, safe and "minimally-processed" foods has led to pioneering research activities in the emerging non-thermal technology of food processing. Cold plasma is such an innovative and promising technology that offers several potential applications in the food industry. It uses the highly reactive, energetic and charged gas molecules and species to decontaminate the food and package surfaces and preserve the foods without causing thermal damage to the nutritional and quality attributes of food. Cold plasma technology showed promising results about the inactivation of pathogens in the food industry without affecting the food quality. It is highly effective for surface decontamination of fruits and vegetables, but extensive research is required before its commercial utilization. Recent patents are focused on the applications of cold plasma in food processing and preservation. However, further studies are strongly needed to scale up this technology for future commercialization and understand plasma physics for getting better results and expand the applications and benefits. This review summarizes the emerging trends of cold plasma along with its recent applications in the food industry to extend shelf life and improve the quality of food. It also gives an overview of plasma generation and principles including mechanism of action. Further, the patents based on cold plasma technology have also been highlighted comprehensively for the first time.

Penicillin G acylase production by Mucor griseocyanus and the partial genetic analysis of its pga gene.

Penicillin acylases (penicillin amidohydrolase, EC 3.5.1.11) are a group of enzymes with many applications within the pharmaceutical industry, and one of them is the production of semi-synthetic beta-lactam antibiotics. This enzyme is mainly produced by bacteria but also by some fungi. In the present study, the filamentous fungus Mucor griseocyanus was used to produce penicillin acylase enzyme (PGA). Its ability to express PGA enzyme in submerged fermentation process was assessed, finding that this fungal strain produces the biocatalyst of interest in an extracellular way at a level of 570 IU/L at 72 h of fermentation; in this case, a saline media using lactose as carbon source and penicillin G as inducer was employed. In addition, a DNA fragment (859 bp) of the pga from a pure Mucor griseocyanus strain was amplified, sequenced, and analyzed in silico. The partial sequence of pga identified in the fungi showed high identity percentage with penicillin G acylase sequences deposited in NCBI through BLAST, especially with the ß subunit of PGA from the Alcaligenes faecalis bacterium¸ which is a region involved in the catalytic function of this protein. Besides, the identification of domains in the penicillin G acylase sequence of Mucor griseocyanus showed three conserved regions of this protein. The bioinformatic results support the identity of the gen as penicillin G acylase. This is the first report that involves sequencing and in silico analysis of Mucor griseocyanus strain gene encoding PGA.

Production of Bioactive Peptides from Lactic Acid Bacteria: A Sustainable Approach for Healthier Foods.

Traditional fermented foods where lactic acid bacteria (LAB) are present have been associated with beneficial effects on human health, and some of those benefits are related to protein-derived products. Peptides produced by LAB have attracted the interest of food industries because of their diverse applications. These peptides include ribosomally produced (bacteriocins) and protein hydrolysates by-products (bioactive peptides), which can participate as natural preservatives and nutraceuticals, respectively. It is essential to understand the biochemical pathways and the effect of growth conditions for the production of bioactive peptides and bacteriocins by LAB, in order to suggest strategies for optimization. LAB is an important food-grade expression system that can be used in the simultaneous production of peptide-based products for the food, animal, cosmetic, and pharmaceutical industries. This review describes the multifunctional proteinaceous compounds generated by LAB metabolism and discusses a strategy to use a single-step production process, using an alternative protein-based media. This strategy will provide economic advantages in fermentation processes and will also provide an environmental alternative to industrial waste valorization. New technologies that can be used to improve production and bioactivity of LAB-derived peptides are also analyzed.

Purification and biochemical characterization of an Aspergillus niger phytase produced by solid-state fermentation using triticale residues as substrate.

In this study, an extracellular phytase produced by Aspergillus niger 7A-1, was biochemically characterized for possible industrial application. The enzyme was purified from a crude extract obtained by solid-state fermentation (SSF) of triticale waste. The extract was obtained by microfiltration, ultrafiltration (300, 100 and 30 kDa) and DEAE-Sepharose column chromatography. The molecular weight of the purified enzyme was estimated to be 89 kDa by SDS-PAGE. The purified enzyme was most active at pH 5.3 and 56 °C, and retained 50% activity over a wide pH range of 4 to 7. The enzymatic thermostability assay showed that the enzyme retained more than 70% activity at 80 °C for 60 s, 40% activity for 120 s and 9% after 300 s. The phytase showed broad substrate specificity, a Km value of 220 µM and Vmax of 25 µM/min. The purified phytase retained 50% of its activity with phosphorylated compounds such as phenyl phosphate, 1-Naphthyl phosphate, 2-Naphthyl phosphate, p-Nitrophenyl phosphate and Glycerol-2-phosphate. The inhibition of phytase activity by metal ions was observed to be drastically inhibited (50%) by Ca++ and was slightly inhibited (10%) by Ni++, K+, and Na+, at 10 and 20 mM concentrations. A positive effect was obtained with Mg++, Mn++, Cu++, Cd++ and Ba++ at 25 and 35% with stimulatory effect on the phytase activity.

Process alternatives for bioethanol production from mango stem bark residues.

Three alternatives for bioethanol production from pretreated mango stem bark after maceration (MSBAM) were evaluated as a biorefinery component for the mango agroindustry. These included separate hydrolysis and fermentation (SHF), simultaneous saccharification and fermentation (SSF), and pre-saccharification followed by simultaneous saccharification and fermentation (PSSF). The effects on ethanol concentration, yield and productivity of pretreated MSBAM solids loading, Tween 20 addition, and temperature were used for process comparisons. The highest yields for the SHF, SSF, and PSSF process alternatives were 58.8, 81.6, and 84.5%, respectively. Since saccharification and fermentation are carried out in the same vessel in the SSF alternative, and no significant SSF and PSSF differences in ethanol concentration were observed, SSF is recommended as the best process configuration.

Trichoderma sp. spores and Kluyveromyces marxianus cells magnetic separation: Immobilization on chitosan-coated magnetic nanoparticles.

In the present study, the interactions between chitosan-coated magnetic nanoparticles (C-MNP) and Trichoderma sp. spores as well as Kluyveromyces marxianus cells were studied. By Plackett-Burman design, it was demonstrated that factors which directly influenced on yeast cell immobilization and magnetic separation were inoculum and C-MNP quantity, stirring speed, interaction time, and volume of medium, while in the case of fungal spores, the temperature also was disclosed as an influencing factor. Langmuir and Freundlich models were applied for the mathematical analysis of adsorption isotherms at 30°C. For Trichoderma sp. spore adsorption isotherm, the highest correlation coefficient was observed for lineal function of Langmuir model with a maximum adsorption capacity at 5.00E + 09 spores (C-MNP g-1). Adsorption isotherm of K. marxianus cells was better adjusted to Freundlich model with a constant (Kf) estimated as 2.05E + 08 cells (C-MNP g-1). Both systems may have a novel application in fermentation processes assisted with magnetic separation of biomass.

Cellulases immobilization on chitosan-coated magnetic nanoparticles: application for Agave Atrovirens lignocellulosic biomass hydrolysis.

In the present study, Trichoderma reesei cellulase was covalently immobilized on chitosan-coated magnetic nanoparticles using glutaraldehyde as a coupling agent. The average diameter of magnetic nanoparticles before and after enzyme immobilization was about 8 and 10 nm, respectively. The immobilized enzyme retained about 37 % of its initial activity, and also showed better thermal and storage stability than free enzyme. Immobilized cellulase retained about 80 % of its activity after 15 cycles of carboxymethylcellulose hydrolysis and was easily separated with the application of an external magnetic field. However, in this reaction, K m was increased eight times. The immobilized enzyme was able to hydrolyze lignocellulosic material from Agave atrovirens leaves with yield close to the amount detected with free enzyme and it was re-used in vegetal material conversion up to four cycles with 50 % of activity decrease. This provides an opportunity to reduce the enzyme consumption during lignocellulosic material saccharification for bioethanol production.

Thermodynamics of chitinase partitioning in soy lecithin liposomes and their storage stability.

The goal of this study was to define the partitioning behavior of chitinase from Trichoderma spp. in soy lecithin liposomes, using a thermodynamic approach based on the partitioning variation with temperature. An effort has been made to define the liposomes, as well as free and immobilized enzyme stability during storage at 4 and 25 °C. The partition coefficients (K (o/w)) were greater than 1; therefore, the standard free energies of the enzyme transfer were negative, indicating an affinity of the enzymes for encapsulation in liposomes. The enthalpy calculation led to the conclusion that the process is exothermic. The presence of enzyme decreased the liposome storage stability from 70 days to an approximately 20 days at 25 °C and 30 days at 4 °C. Monitoring of the liposome's diameter demonstrated that their size and concentration decreased during storage. The liposome's diameters ranged from 1.06 to 3.30 µm. The higher percentage of liposome corresponded to a diameter range from 1.06 to 1.34 µm. This percentage increased during storage. There were no evidences for liposome fusion process. The stability of immobilized enzyme was increased in comparison with free chitinase.