Fungal carbonatogenesis process mediates zinc and chromium removal via statistically optimized carbonic anhydrase enzyme.

INTRODUCTION: With rapid elevation in population, urbanization and industrialization, the environment is exposed to uncontrolled discharge of effluents filled with broad-spectrum toxicity, persistence and long-distance transmission anthropogenic compounds, among them heavy metals. That put our ecosystem on the verge or at a stake of drastic ecological deterioration, which eventually adversely influence on public health. Therefore, this study employed marine fungal strain Rhodotorula sp. MZ312369 for Zn2+ and Cr6+ remediation using the promising calcium carbonate (CaCO3) bioprecipitation technique, for the first time. RESULTS: Initially, Plackett-Burman design followed by central composite design were applied to optimize carbonic anhydrase enzyme (CA), which succeeded in enhancing its activity to 154 U/mL with 1.8-fold increase comparing to the basal conditions. The potentiality of our biofactory in remediating Zn2+ (50 ppm) and Cr6+ (400 ppm) was monitored through dynamic study of several parameters including microbial count, CA activity, CaCO3 weight, pH fluctuation, changing the soluble concentrations of Ca2+ along with Zn2+ and Cr6+. The results revealed that 9.23 × 107 ± 2.1 × 106 CFU/mL and 10.88 × 107 ± 2.5 × 106 CFU/mL of cells exhibited their maximum CA activity by 124.84 ± 1.24 and 140 ± 2.5 U/mL at 132 h for Zn2+ and Cr6+, respectively. Simultaneously, with pH increase to 9.5 ± 0.2, a complete removal for both metals was observed at 168 h; Ca2+ removal percentages recorded 78.99% and 85.06% for Zn2+ and Cr6+ remediating experiments, respectively. Further, the identity, elemental composition, functional structure and morphology of bioremediated precipitates were also examined via mineralogical analysis. EDX pattern showed the typical signals of C, O and Ca accompanying with Zn2+ and Cr6+ peaks. SEM micrographs depicted spindle, spherical and cubic shape bioliths with size range of 1.3 ± 0.5-23.7 ± 3.1 µm. Meanwhile, XRD difractigrams unveiled the prevalence of vaterite phase in remediated samples. Besides, FTIR profiles emphasized the presence of vaterite spectral peaks along with metals wavenumbers. CONCLUSION: CA enzyme mediated Zn2+ and Cr6+ immobilization and encapsulation inside potent vaterite trap through microbial biomineralization process, which deemed as surrogate ecofriendly solution to mitigate heavy metals toxicity and restrict their mobility in soil and wastewater.

Antibacterial, Antifungal and Antibiofilm Activities of Silver Nanoparticles Supported by Crude Bioactive Metabolites of Bionanofactories Isolated from Lake Mariout.

Lake Mariout is one of the polluted coastal marine ecosystems in Egypt which is considered to be a reservoir of serious effluents from different anthropogenic activities. Such selective pressure enforces indigenous microbial populations to acquire new advantageous themes. Thus, in this study, two Streptomyces strains were screened, from Lake Mariout's sediment for bioreduction of 5 mM AgNO3. Both strains were identified molecularly; their biochemical and physiological characterization revealed their ability to secrete bioactive metabolites with antagonistic activity. The cultural and incubation conditions influencing AgNPs productivity were evaluated. Subsequently, the physicochemical properties of the biofabricated AgNPs were pursued. UV-Vis spectroscopy detected surface plasmon resonance at range 458-422 nm. XRD indicated crystalline, pure, face-centered cubic AgNPs; EDX demonstrated strong silver signal at 3.5 keV. Besides, FT-IR and TGA analysis unveiled self-stabilization and functionalization of AgNPs by bioorganic molecules. However, electron microscopy micrographs depicted numerous uniform spherical AgNPs (1.17-13.3 nm). Potent bactericidal and fungicide activity were recorded by zone of inhibition assay at 50 µg/mL. Further, the antibiofilm activity was exerted in a dose-dependent manner. Moreover, the conjugation of AgNPs with the crude bioactive metabolites of both bionanofactories ameliorated the antimicrobial potency, reflecting a synergistic efficiency versus examined pathogens (free-living and biofilm).

Revealing detrimental effects of various DC electrical energy conditions on different multidrug resistant bacteria: a comprehensive study.

The arbitrary discharge of contaminated wastes, especially that encompass multidrug resistant microbes (MDR), would broaden the circle of epidemic diseases such as COVID-19, which in turn deteriorate definitely the whole socioeconomics. Therefore, the employment of electrical stimulation techniques such as direct current (DC) with low energy considers being effective tool to impede spontaneous changes in microbial genetic makeup, which increases the prevalence of MDR phenomenon. Herein, the influence of different electric energies generated by DC electric field, volts and time on MDR-bacteria that are categorized among the highly ranked nosocomial pathogens, was scrutinized. Wherein, Pseudomonas aeruginosa, Escherichia coli, Staphylococcus aureus and Enterococcus faecalis were examined as paradigms of Gram-negative and Gram-positive pathogens. The results declared the significant superior antagonizing potency of electric energy in a dose-dependent modality rather than the applied volts or exposure time. Notably, the exposure of bacterial cultures to140 J inhibited the bacterial count by > 78% and the range of 47-73% for Gram-negative and Gram-positive, respectively. While the suppression in their metabolic activity assessed by > 75% and 41-68%, respectively; reflecting the capability of electrical energy to induce viable but non-culturable (VBNC) state. Similarly, the results of total protein, extracellular protein content and lactate dehydrogenase activity emphasized the cell wall deterioration and losing of cell membrane integrity. Additionally, the elevating in ROS upon DC-exposure participated in DNA fragmentation and plasmid decomposability by the range of 33-60%. Further, SEM micrographs depicted drastic morphological deformations after electrical treatment. Strikingly, DC-treatment impaired antibiotic resistance of the examined strains against several antibiotics by > 64.2%. Generally, our comparative detailed study revealed deleterious potentiality of different DC-protocols in defeating microbial pollution, which could be invested as efficient disinfectant alternative in various sectors such as milk sterilization and wastewater purification.

Unveiling the anticancer potentiality of single cell oils produced by marine oleaginous Paradendryphiella sp. under optimized economic growth conditions.

Bioprospecting about new marine oleaginous fungi that produce advantageous bioproducts in a green sustainable process is the key of blue bioeconomy. Herein, the marine Paradendryphiella sp. was utilized for single cell oils (SCOs) production economically, via central composite design, the lipid content enhanced 2.2-fold by 5.5 g/L lipid yeild on seawater-based media supplemented with molasses concentration 50 g/L, yeast extract, 2.25 g/L at initial pH value (5.3) and 8 days of static incubation. Subsequently, the fatty acid methyl esters profiles of SCOs produced on optimized media under different abiotic conditions were determined; signifying qualitative and quantitative variations. Interestingly, the psychrophilic-prolonged incubation increased the unsaturation level of fatty acids to 59.34%, while ω-6 and ω-3 contents representing 23.53% and 0.67% respectively. Remarkably, it exhibited the highest EC100 dose by 677.03 µg/mL on normal human lung fibroblast Wi-38 cells. Meanwhile, it showed the highest inhibiting proliferation potential on cancer cell lines of A549, MDA-MB 231 and HepG-2 cells by 372.37, 417.48 and 365.00 µg/mL, respectively. Besides, it elevated the oxidative stress, the expression of key apoptotic genes and suppressed the expression of key oncogenes (NF-κB, BCL2 and cyclin D); implying its promising efficacy in cancer treatment as adjuvant drug. This study denoted the lipogenesis capacity of Paradendryphiella sp. under acidic/alkaline and psychrophilic/mesophilic conditions. Hereby attaining efficient and economic process under seasonal variation with different Egyptian marine sources to fill the gap of freshwater crisis and simultaneously preserve energy.