In the present work, the biosynthesis of silver-nanoparticles (AgNP) was evaluated using the aqueous extract from Justicia spicigera. The obtained silver nanoparticles were characterized using UV-visible spectroscopic techniques, energy dispersive X-ray spectrometers (EDS), zeta potential and dynamic light scattering. The antimicrobial activity of biosynthesized AgNP was tested against foodborne bacteria (Bacillus cereus, Klebsiella pneumoniae and Enterobacter aerogenes) and phytopathogenic fungi (Colletotrichum sp., Fusarium solani, Alternaria alternata and Macrophomina phaseolina). The elemental profile of synthesized nanoparticles using J. spicigera shows higher counts at 3keV due to silver, confirming the formation of silver nanoparticles. Scanning electron microscopy (SEM) analysis showed a particle size between 86 and 100nm with spherical morphology. AgNP showed effective antibacterial and antifungal activity against the tested organisms principally with B. cereus, K. pneumoniae, E. aerogenes, A. alternata and M. phaseolina. Therefore, further studies are needed to confirm the potential of AgNP from J. spicigera in the control of indicator organisms under field conditions.

In the present study the characterization and properties of silver nanoparticles from Prosopis glandulosa leaf extract (AgNPs) were investigated using UV–Vis spectroscopic techniques, energy dispersive X-ray spectrometers (EDS), zeta potential and dynamic light scattering. The UV–Vis spectroscopic analysis showed the absorbance peaked at 487 nm, which indicated the synthesis of silver nanoparticles. The experimental results showed silver nanoparticles had Z-average diameter of 421 nm with higher stability (−200 mV). The EDS analysis also exhibited presentation of silver element. Additionally, the different concentrations of AgNPs (25, 50, 75 and 100 mg/mL) showed antibacterial activity against Acinetobacter calcoaceticus and Bacillus cereus. Finally, AgNPs from leaf extracts of P. glandulosa may be used as an agent of biocontrol of microorganism of importance medical. However, further studies will be needed to fully understand the antimicrobial activity of silver nanoparticles obtain from P. glandulosa.

Feathers are the most prevalent agricultural waste generated by chicken farms, polluting the environment and wasting protein resources as a result of the accumulation of large amounts of feathers. Therefore, keratinase-producing microorganisms represent a promising potential technique for the degradation of feather waste. Streptomyces netropsis A-ICA and Bacillus subtilis ALICA, previously isolated from the rhizosphere of desert plants (Larrea tridentata and Prosopis juliflora) respectively, were assessed for their feather-degradation ability. Keratinase activity was optimized using various parameters, including incubation time, pH, temperature, and feather concentration. The maximum keratinase activity of S. netropsis A-ICA and B. subtilis ALICA (113.6 ± 5.1 and 135.6 ± 4.1 U/mL) was obtained at the 5th and 3rd day of incubation with initial pH of 7.0 and 7.5 at 25 and 30 °C, and 1% (w/v) of chicken feather, respectively. Under the optimized conditions, the concentration of soluble protein in the feather hydrolysate reached 423.3 ± 25 and 565.3 ± 7.7 µg/mL, with feathers weight loss of 84 ± 2 and 86± 1.5% by S. netropsis A-ICA and B. subtilis ALICA, respectively. The highest disulphide bond reductase activity reached 10.7 ± 0.4 and 10.96 ± 1.1 U/mL, after five and three days of inoculation with S. netropsis A-ICA and B. subtilis ALICA, respectively. Furthermore, the antioxidant activity of feather protein hydrolysate obtained by S. netropsis A-ICA and B. subtilis ALICA was evaluated using DPPH radical-scavenging activity, which exhibited a significant antioxidant potential with an IC₅₀ value of 0.8 and 0.6 mg/mL. The 3D models of detected keratinases in both strains showed high similarity with subtilisin family. Further, the docking results clarified the importance of GSG and VVVFTP domains in B. subtilis and beta-keratin, respectively. The present study revealed the keratinolytic potential of S. netropsis A-ICA and B. subtilis ALICA in chicken feather degradation, which have potential application value and may be exploited as supplementary protein and antioxidant in animal feed formulations.

Hops contain a wide variety of polyphenolic compounds with diverse antimicrobial properties. This study aimed to evaluate the impact of temperature on the bioactive components of samples of aqueous extracts of hops with different characteristics. A central compound rotating design model was used in order to obtain optimal conditions of temperature and extract concentration to inhibit Fusarium oxysporum and Alternaria solani. At intermediate temperatures according to the design of experiments, significant effects on antifungal activity were observed. The optimal conditions with antifungal activity were at a concentration of 160 mg/mL and a temperature of 65 °C to obtain mycelial diameters ≤ 25 mm. The bioactive compounds were shown in the FT-IR spectrum after each heat treatment of both samples; significant changes were observed in the bands between 2786 to 3600 cm⁻¹ and 1022 to 1729 cm⁻¹. The content of total phenols and flavonoids showed a concentration increase of 4.54 to 6.24 mg GAE/g and 6.21 to 8.12 mg QE/g from an initial evaluation temperature of 25 °C to 57.5 °C, respectively, benefited by the heating temperature, enhancing antifungal activity. However, when increasing the temperature ≥90 °C, a tendency to decrease the concentration of bioactive compounds was observed, probably due to their denaturation due to the effect of temperature and exposure time, being non-thermolabile compounds at high temperatures. These aqueous extracts are an alternative to effective natural antifungals.

This study aimed to produce biochar with an energy value in the range of sub-bituminous carbon by investigating the effect of oxidative and non-oxidative torrefaction on the torrefaction yield and fuel properties of wheat straw. Three independent variables were considered at different levels: temperature (230, 255, 280, 305 °C), residence time (20, 40, 60 min), and reaction atmosphere (0, 3, 6 vol% O₂; N₂ balance); and three dependent variables: mass yield, energy yield, and percentage increase in higher heating value (HHV). The results showed that it is possible to produce a sub-bituminous carbon type C biochar using oxidative torrefaction, significantly reducing time and temperature compared with non-oxidative torrefaction. The optimum torrefaction conditions were 287 °C–20 min–6.0% O₂, which increased the HHV of wheat straw from 13.86 to 19.41 MJ kg⁻¹. The mass and energy yields were 44.11 and 61.78%, respectively. The physicochemical and fuel properties of the obtained biochar were improved compared with the raw biomass. The atomic O/C ratio was reduced from 1.38 to 0.86. In addition, the hydroxyl groups in the lignocellulosic structure decreased and the hemicellulose content decreased from 26.08% to 1.61%. This improved grindability, thermal stability, porosity, and hydrophobicity.