Appl. Biosci., Volume 3, Issue 2 (June 2024) – 4 articles

The utilization of microalgae as a green carbon source for chemical production has attracted attention for its potential use in sustainable and climate-friendly solutions. This study investigates the growth of Dunaliella salina, a unicellular green microalga, in response to salinity variations and water and seawater addition to compensate for evaporation in open cultures. The impact of continuous and non-continuous water addition, as well as seawater addition, on the growth of D. salina was analyzed though tank tests. The results showed that different water-addition methods did not significantly influence cell concentrations, indicating the organism’s resilience to salinity changes. Continuous water addition maintained stable salinity levels at 12%, but required continuous monitoring, while non-continuous addition reduced the intervention frequency. The overall results showed that a salinity range between 12 and 15% did not affect microalgae growth, suggesting flexibility in evaporation-loss compensation methods based on cultivation-system specifics and resource availability. Maintaining consistent biomass regardless of the water-addition method used suggests sustainable production within the tested salinity range, with seawater addition making microalgae cultivation more adaptable to regions with varying water availability. Further research, including outdoor pilot tests, is recommended to validate and extend these findings to natural environments. Full article

Growing demands for sustainable and ecological nanoparticle synthesis methods have incentivized the scientific community to develop new approaches to counteract these challenges. Green synthesis resorts to biocomponents obtained from plants, bacteria, fungi, and other organisms to synthesize nanostructures, with beneficial gains in the economic and ecological cost associated with the process, simplicity of the process, and resource efficiency. Moringa oleifera, a native plant originally from India with immense nutritive value, has long been used by researchers in the biosynthesis of nanoparticles. Leaves, flowers, bark, and seeds are among the “miracle tree” parts that can be used in nanoparticle green synthesis. Moringa oleifera seed cake, a by-product obtained from defatted seeds, is often overlooked due to its apparent low commercial value. The main objective of this review is to highlight the recent findings reported in the literature on nanoparticles/nanocomposites synthesized with seed cake biocompounds acting as reducing/capping agents. Furthermore, we analyzed the methods currently employed for the extraction of bioactive compounds. Moringa oleifera seed for industrial applications was also addressed. Full article

The emergence of bacteria resistant to bacteriophage (phage) infection may compromise the success and effectiveness of phage therapy. The aim of this study was to evaluate the in vitro antibacterial activity of five novel phages, as well as the emergence of bacterial resistance to phage infections. The antibacterial activity of lytic phages was evaluated against standard strains of Pseudomonas aeruginosa (ATCC 27853), Escherichia coli (ATCC 25927), Enterococcus faecalis (ATCC 29212) and Staphylococcus aureus (ATCC 6538). Phages were initially grown in the presence of host bacteria in an exponential growth phase, then purified and titrated. In a second exposure, 20 μL of each phage was inoculated with 10⁶ CFU/mL of P. aeruginosa/E. coli/E. faecalis/S. aureus, separately. In a third exposure, resistant colonies were isolated, cultivated and exposed again to the phages. Bacterial colonies resistant to phage infection after the third exposure were evaluated for their susceptibility profile to different antibiotics via the diffusion disk technique. The diameters of the inhibition halos were evaluated with Image J software (version 1.54g) and the definition of the susceptibility profile to antibiotics was determined according to the European Committee on Antimicrobial Susceptibility Testing (EUCAST) criteria. In addition, fourteen cocktails with different phages were formulated to evaluate the emergence of a bacterial resistance to phage infections. The phages exhibited specificity for P. aeruginosa and did not infect E. coli, E. faecalis and S. aureus. The presence of bacterial colonies resistant to phage infection in the three successive exposures was identified, and the bacterial resistance to phage infection was confirmed in all phages titrated at 10⁸ PFU/mL, in four phages titrated at 10¹⁰ PFU/mL and in one phage titrated at 10¹³ PFU/mL. The development of a resistance to infection by phages (~10⁸ PFU/mL) did not change the susceptibility profile of P. aeruginosa to antibiotics and, when evaluating the emergence of a resistance to infection by phage cocktails (~10⁸ PFU/mL, ~10¹⁰ PFU/mL, ~10¹³ PFU/mL), bacterial resistance to phage infection was confirmed in all cocktails with phages titrated at 10⁸ PFU/mL, in ten cocktails with phages titrated at 10¹⁰ PFU/mL and in seven cocktails with phages titrated at 10¹³ PFU/mL. In conclusion, the presence of resistant P. aeruginosa colonies to phage infection after successive exposures was evidenced, although some phages at title ~10¹⁰ PFU/mL and ~10¹³ PFU/mL were effective in inhibiting the growth of resistant colonies. The development of resistance did not change the susceptibility profile of P. aeruginosa to antibiotics. Variants of P. aeruginosa that were resistant to phage infection were isolated and their resistance to infection via the phage cocktail was demonstrated regardless of the viral titer, although some cocktails at title ~10¹⁰ PFU/mL and ~10¹³ PFU/mL were effective in inhibiting the growth of resistant colonies. Despite the emergence of bacterial variants resistant to phage infection, new studies involving the applicability of phages in the control of infections must be conducted. Full article

Introduction: Mortality from acute radiation syndrome is frequently caused by hematopoietic or gastrointestinal radiotoxicity, the latter of which currently has no effective treatment. Transforming growth factor-beta 3 (TGF-β3) may decrease the severity of radiation-induced gastrointestinal damage in mice. In addition, treatment with TGF-β3 may alleviate radiation-induced fibrosis. Objectives: The current study aimed to investigate the effect of TGF-β3 treatment on acute and late radiotoxicity in whole body irradiated mice. Methods: C57BL/6J mice were total body irradiated with 8.5 Gy X-rays with or without shielding of one hind leg to alleviate hematopoietic radiotoxicity. The effects of intravenous TGF-β3 treatment were investigated. Body weight and pain expression were monitored. Intestine, lung, and liver tissues were preserved and analyzed. Alpha smooth muscle actin (α-SMA) expression in MRC-5 cells after 3.5 Gy X-irradiation combined with TGF-β3 treatment was analyzed using flow cytometry. Results: All total body irradiated animals died within ten days after irradiation. Ninety-three percent of femur-shielded mice survived until sampling or termination. No effect of TGF-β3 treatment was observed in either group. No increase in collagen content was detected in the lungs or liver from irradiated mice regardless of TGF-β3 treatment. In vitro, α-SMA expression increased synergistically after irradiation and TGF-β3 treatment. Conclusions: Shielding of the femur during total body irradiation decreased acute gastrointestinal radiation toxicity and increased survival. TGF-β3 treatment did not impact symptoms or survival. TGF-β3 treatment and irradiation increased α-SMA expression in MRC-5 cells synergistically. Full article