Nanostructured materials (NSMs) of silver (Ag@TiO₂) and copper (TiO₂-Cu²⁺) doped titanium dioxide were synthesized, fully characterized, and evaluated for their antimicrobial efficiency and effects onArabidopsis thaliana. The NSMs were prepared using an environmentally benign route. The physicochemical properties of the materials were determined with analytical techniques. These materials are active under visible light, exhibit a small size (10–12 nm), are crystalline (anatase), and liberate metal ions (Ag⁺and Cu²⁺) in solution. Microbicide activity was observed inE. coliC600 andS. cerevisiaeW303 strains treated with several concentrations of Ag@TiO₂and TiO₂-Cu²⁺, radiated and nonradiated, and after different times. Higher inactivation was achieved with Ag@TiO₂inE. coli, with value of log inactivation of 2.2 with 0.5 mg/mL after 4 h, than inS. cerevisiae, with a log inactivation of 2.6 with 10 mg/mL after 24 h. The impact of these NSMs in plants was evaluated inArabidopsis thalianaCol-0 strain exposed to such materials at different conditions and concentrations, and physical and biochemical effects were analyzed. Seeds exposed to NSMs did not show effects on germination and growth. However, seedlings treated with these materials modified their growth and their total chlorophyll content.

Wastewater can be reused after a treatment process and compliance with high quality standards that guarantee its safe use. The wastewater treatment plant of the Autonomous University of Aguascalientes (AUA), like others, uses primary, secondary, and tertiary processes. The tertiary process followed is chlorination and is used to eliminate microorganisms from the secondary process. Although water of acceptable quality is obtained with chlorine, there is evidence that toxic substances are generated when reacting with organic matter, so alternatives to the use of chlorination have been analyzed. In the present study, silver nanoparticles were synthesized from the aqueous extract of the Opuntia ficus indica fruit peel (OfAgNPs), by reducing a 2 mM solution of AgNO₃. OfAgNPs were characterized by UV-visible spectroscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy, atomic absorption spectroscopy, and dynamic light scattering, in addition to his electrophoretic mobility. The OfAgNPs are spherical, with an average particle size distribution of nm, relatively stable at room temperature, negatively charged ( mV), and composed of 61.29% silver. The activity of OfAgNPs was evaluated in water from the effluent of the AUA treatment plant, before and after chlorination, and inhibition of bacteria Escherichia coli var 1, Enterobacter aerogenes var 1, Citrobacter freudi var 2, atypical E. coli, and aerobic mesophilic microorganism was tested.

Guava fruit softening is a crucial process during ripening and this process involves a number of enzymes that modifies the cell wall. Two of the enzymes that regulate this process are (a) the β-1, 4-endoglucanase 17 (BEG) which hydrolyze β-1, 4 bonds from cellulose and hemicellulose, and (b) β-galactosidase (BGA) that hydrolyzes pectin chains. Bioinformatics and expression analysis information on these genes is limited in guava fruit. A fragment of a β-1, 4-endoglucanase 17 (PgE17), and another of a β-galactosidase (PgGa1) were identified. These sequences have a similarity of more than 85% with those reported in the NCBI database. In the guava genome, one homologous sequence was found for PgE17 in Chr 4 and two homologous to PgGa1: one in Chr 3 and the other one in Chr 6. Putative protein PgE17 contains part of the glyco_hydro_9 domain. Putative protein PgGa1 has a part of the glyco_hydro_35 domain. Phylogenetic analysis of PgE17 and PgGa1 revealed that both are highly conserved inside the Myrtaceae family. In silico expression analysis showed that both PgE17 and PgGa1 work in a coordinated way with other cell wall modifier enzymes. Expression of these genes was found in all the guava samples analyzed. However, the highest expression was found in the fruit in the breaking and ripe states. A β-1, 4-endoglucanase 17, and β-galactosidase 1 sequences were identified. PgE17 and PgGa1 are expressed in all the plant tissues, and fruit ripening states. Although, the highest expression was on breaker and ripe states.

Silver nanoparticles (AgNPs) were produced by green synthesis using Raphanus sativus (RsAgNPs), Beta vulgaris (BvAgNPs), and Ocimum basilicum (ObAgNPs) leaf extracts as reducing agents. Plant phytochemical composition analysis indicated that they contain phenolic compounds that can participate in the synthesis reaction as flavonoids. Synthesized AgNPs presented maximal absorption peak at 430nm (RsAgNP), 440nm (BvAgNP), and 420nm (ObAgNP) in ultraviolet-visible spectrophotometry analysis. Scanning electron microscopy and energy dispersive X-ray spectroscopy analysis showed that RsAgNPs are 76nm diameter spheres made of up to 54.1 silver, the BvAgNPs are 78nm diameter spheres with 39.76 silver, and the ObAgNPs are cubes of 99nm edges with 69.74 silver. The found Z potential values indicate that all the obtained AgNPs are stable in phosphate buffer. A disinfection of 100 and 90 was achieved for the in vitro culture of Arabidopsis thaliana and Psidium guajava (guava) seeds, respectively, with all AgNPs synthesized. Treatment with these AgNPs showed no negative effects on germination, and on the contrary, in guava, a higher germination percentage was observed when the seeds were exposed to RsAgNPs. Only at high concentration (10mg/mL) of AgNPs, the growth of A. thaliana was decreased, while at low concentration (0.01mg/mL) of ObAgNP and BvAgNPs, higher growth was showed, specifically 60 and 40 more than the control, respectively. All AgNPs showed antimicrobial activity against Escherichia coli and Klebsiella oxytoca which are bacteria of clinical interest, and against Agrobacterium tumefaciens, a bacterium used in the genetic transformation of plants.