Detection of oxalyl-CoA decarboxylase (oxc) and formyl-CoA transferase (frc) genes in novel probiotic isolates capable of oxalate degradation in vitro.

Oxalate degradation is one of lactic acid bacteria's desirable activities. It is achieved by two enzymes, formyl coenzyme A transferase (frc) and oxalyl coenzyme A decarboxylase (oxc). The current study aimed to screen 15 locally isolated lactic acid bacteria to select those with the highest oxalate degradation ability. It also aimed to amplify the genes involved in degradation. MRS broth supplemented with 20 mM sodium oxalate was used to culture the tested isolates for 72 h. This was followed by an enzymatic assay to detect remaining oxalate. All isolates showed oxalate degradation activity to variable degrees. Five isolates demonstrated high oxalate degradation, 78 to 88%. To investigate the oxalate-degradation potential of the selected isolates, they have been further tested for the presence of genes that encode for enzymes involved in oxalate catabolism, formyl coenzyme A transferase (frc) and oxalyl coenzyme A decarboxylase (oxc). Three strains showed bands with the specific OXC and FRC forward and reverse primers designated as (SA-5, 9 and 37). Species-level identification revealed Loigolactobacillus bifermentans, Lacticaseibacillus paracasei, and Lactiplantibacillus plantarum. Preliminary results revealed that the tested probiotic strains harbored both oxc and frc whose products are putatively involved in oxalate catabolism. The probiotic potential of the selected strains was evaluated, and they showed high survival rates to both simulated gastric and intestinal fluids and variable degrees of antagonism against the tested Gram-positive and negative pathogens and were sensitive to clarithromycin but resistant to both metronidazole and ceftazidime. Finally, these strains could be exploited as an innovative approach to establish oxalate homeostasis in humans and prevent kidney stone formation.

Assessing the effectiveness of green synthesized zinc oxide nanoparticles in controlling multidrug-resistant clinical bacteria.

Multi-drug resistant pathogenic bacteria are life threaten agent associated with the misuse and overuse of antibiotics. The biological synthesis of metal oxide nanoparticles is a promising alternative treatment. The current study reported the synthesis of zinc oxide nanoparticles (ZnONPs) using different plants extracts of garlic (Allium sativum), ginger (Zingiber officinale), and lemon (Citrus lemon). The plant extracts not only acts as reducing agents but as stabilizing agents for the produced nanoparticles. Biosynthesized zinc oxide nanoparticles (ZnONPs) were confirmed by transmission electron microscopy (TEM), scanning electron microscopy (SEM) with energy-dispersive X-ray studies (EDX), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and ultraviolet-visible (UV-vis) spectroscopy. XRD analysis confirmed the production of pure ZnONPs. UV-vis spectroscopy revealed the presence of ZnONPs and reported the characteristic absorption peak of ZnONPs at 370 nm. SEM and TEM confirmed the shape and size of nanoparticles, with an average mean size of 0.3-11.40 nm. This study reported the antibacterial activity and minimum inhibitory concentration of biosynthesized ZnONPs using the broth microdilution method against some clinical pathogenic bacteria. This study also reported the antimicrobial activity of ZnONPs prepared with garlic extract against Enterococcus sp. and Pseudomonas sp. While, those prepared with ginger extract were effective against Enterococcussp. and methicillin-resistant Staphylococcus aureus. ZnONPs synthesized by garlic extract were more powerful and effective than ZnONPs synthesized by ginger and lemon extracts. Supplementary Information: The online version contains supplementary material available at 10.1007/s12088-022-01048-3.

Biofertilizer effect of some zinc dissolving bacteria free and encapsulated on Zea mays growth.

Crop nutrition depends on zinc for enzymatic, oxidative, and metabolic processes. In the current study 20 different bacteria were isolated from five soil samples collected from different fields in Egypt. Bacterial isolates were screened for their ability to solubilize insoluble zinc oxide and zinc carbonate. The ability of selected isolates to tolerate soluble zinc was determined using different concentrations of (ZnSO4). Three bacterial isolates were selected with efficiency in solubilizing zinc oxide and zinc carbonate while tolerating high levels of soluble zinc. Molecular identification by 16S rRNA sequencing of the chosen isolates identified them as B3 (Acinetobacter calcoaceticus), B5 (Bacillus proteolyticus) and C6 (Stenotrophomonas pavanii). Sodium alginate beads formulated with the isolated bacteria were tested for stability under different storage conditions for 3 months. A pot experiment was conducted to study and compare the effect of using chosen isolates as an in vivo Zn solubilizer with amended ZnCO3 either alone or embedded in beads as carrier in the soil and its effect on growth parameters of Zea mays after 2 months. There was an increase in Zn uptake in all treatments compared to the control. However, plants grown in a pot treated with ZnCO3 and Acinetobacter calcoaceticus showed the highest zinc content and plant dry weight as compared to the control. Finally, selected isolates in both free and encapsulated forms showed improved plant growth parameters and higher zinc content and can be applied as biofertilizers to enhance soil fertility.