Microbial-Physical Synthesis of Fe and Fe3O4 Magnetic Nanoparticles Using Aspergillus niger YESM1 and Supercritical Condition of Ethanol

Magnetic Fe and Fe3O4 (magnetite) nanoparticles are successfully synthesized using Aspergillus niger YESM 1 and supercritical condition of liquids. Aspergillus niger is used for decomposition of FeSO4 and FeCl3 to FeS and Fe2O3, respectively. The produced particles are exposed to supercritical condition of ethanol for 1 hour at 300∘ C and pressure of 850 psi. The phase structure and the morphology measurements yield pure iron and major Fe3O4 spherical nanoparticles with average size of 18 and 50 nm, respectively. The crystal size amounts to 9 nm for Fe and 8 nm for Fe3O4. The magnetic properties are measured to exhibit superparamagneticand ferromagnetic-like behaviors for Fe and Fe3O4 nanoparticles, respectively. The saturation magnetization amounts to 112 and 68 emu/g for Fe and Fe3O4, respectively. The obtained results open new route for using the biophysical method for large-scale production of highly magnetic nanoparticles to be used for biomedical applications

Biofilm Formation by Marine Cobetia marina alex and Pseudoalteromonas spp: Development and Detection of Quorum Sensing N-Acyl Homoserine Lactones (AHLs) Molecules

Surfaces submerged in seawater are colonized by various microorganisms, resulting in the formation of heterogenic marine biofilms. This work aims to evaluate the biofilm formation by Cobetia marina alex and doing a comparative study between this promising strain with the two bacterial strains isolated previously from the Mediterranean seawater, Alexandria, Egypt. Three strains; Cobetia marina alex, Pseudoalteromonas sp. alex, and Pseudoalteromonas prydzensis alex were screened for biofilm formation using the crystal violet (CV) quantification method in a single culture. The values of biofilm formed were OD600= 3.0, 2.7, and 2.6, respectively leading to their selection for further evaluation. However, factors affecting biofilm formation by C. marina alex were investigated. Biofilm formation was evaluated in single and multispecies consortia. Synergistic and antagonistic interactions proved in this work lead to the belief that these bacteria have the capability to produce some interesting signal molecules N-acyl Homoserine Lactones (AHLs

Characterization of Biofilm Forming Marine Pseudoalteromonas spp

Biofilm forming bacteria are omnipresent in the marine environment. Pseudoalteromonas is one of the largest within the γ-proteobacteria class, and a member of marine bacteria. Species of Pseudoalteromonas are generally found in association with marine eukaryotes. In this work, we present the isolation and characterization of two strains forming biofilm on rock surface and associated with marine sponge. They were identified using 16SrDNA as Pseudoalteromonas prydzensis alex, and Pseudoalteromonas sp. alex. They showed the highest titer in biofilm formation quantified using the test tube method using crystal violet

Agarase Production by Marine Pseudoalteromonas sp. MHS: Optimization, and Purification

Agar is an essential polysaccharide that has been utilized in numerous fields. Many kinds of literature have been published regarding agarolytic microorganisms’ isolation and agarases biochemical studies. In this search, a local marine agarolytic bacterium associated with marine alga Ulva lactuca surface was isolated and identified as Pseudoalteromonas sp. MHS. The agarase production was parallel to the growth of Pseudoalteromonas sp. MHS as cells displayed a lag phase (2 h), subsequently an exponential growth that prolonged till 10 h where maximum growth (OD550nm = 3.9) was achieved. The enzyme activity increased rapidly as cells increased exponentially where the maximum activity of 0.22 U/mL was achieved after 8h and remained constant till 12 h during the stationary phase of growth. Agarase production was optimized using Plackett-Burman statistical design by measuring enzyme activity as a response and the design was validated using a verification experiment; the activity of the enzyme increased from 0.22 U/mL to 0.29 U/mL. Pseudoalteromonas sp. MHS agarase was partially purified and its molecular weight (MW) was determined by SDSPAGE (15-25 kDa). Agarase showed approximately 94% of its activity at 40 °C. The enzyme stability decreased as the temperature increased; the enzyme could retain about 98, 90, 80, 75, and 60% of its activity at 20, 30, 40, 50, and 60 °C, respectively. Biomass of the red alga Pterocladia capillacea proved to be a suitable substrate for agarase production using Pseudoalteromonas sp. MHS; the enzyme activity recorded after 24 h of incubation was 0.35 U/mL compared to 0.29 U/mL from the optimized medium

Isolation and identification of a prodigiosin-like pigment producer Vibrio sp. isolate from a sea snail Thais sp

Marine bacteria associated with Mediterranean Sea snails have not been explored intensively. The aim of the study was to explore marine pigmented bacteria associated with the sea snail Thais sp. commonly found in Alexandria seashores where a red-pigmented bacterium was isolated and identified as Vibrio sp. based on phenotypic traits and 16S rRNA gene sequence analysis. Based on ultraviolet-visible (UV-vis) spectral and liquid chromatography-mass spectrometry (LC-MS) analysis, the red pigment was identified as a prodigiosin-like pigment. To our knowledge, this is the first report on the isolation of a Vibrio strain from a gastropod able to synthesize prodigiosin. Maximum production (7 mg/L) was achieved after two days in MZM cultures containing 0.5% mannitol and 2.5% soybean meal, pH 7 and statically incubated at 30 °C, using Plackett-Burman factorial design. RT-qPCR revealed that pks-1 and nrps responsible for the biosynthesis of prodigiosin and other bioactive compounds were up-regulated by the addition of sublethal concentrations of imipenem, DMSO, and the heavy metals copper oxide and chromium VI oxide. Through this work it can be concluded that marine invertebrates should be further explored for bacteria producing bioactive compounds whose synthesis can be enhanced or blocked depending on the carbon and nitrogen sources adopted in the fermentation medium. Moreover, the mRNA expression of the genes responsible for prodigiosin-like pigment production can be up-regulated through adopting sub-lethal concentrations of stress inducing compounds as well as co-cultivatio

Potential Egyptian bacterial consortium for oil spill treatment: A laboratory simulation

The purpose of the study was to reach high efficiency of an oil-degrading bacteria to be used in oil-spill treatment separately or with bacterial consortium. The consortium effect on crude oil was examined by GC-MS. The consortium degraded 99.2% of crude oil after 7 days, while Enterobacter sp. ASH, as individual culture, degraded 80% only. This isolate was identified based on 16S rRNA gene sequence analysis, morphological, physiological, and biochemical characterization. ANOVA analysis showed that medium volume and crude oil concentration are the significant factors. The results showed that the mixed consortium showed better biodegradation abilities than E. sp. ASH

Statistical Optimization and Characterization of Prodigiosin from a Marine Serratia rubidaea RAM-Alex

This research sought to determine optimal conditions to maximize prodigiosin production by an indigenous Egyptian marine bacterial strain Serratia rubidaea RAM_Alex. Serratia rubidaea RAM_Alex isolated from bivalve samples of Temsah Lake, Ismailia, Egypt was used to investigate the production of the natural red pigment prodigiosin. Pigment production was assayed in different growth conditions using Nutrient broth as production medium. The water insoluble red pigment was extracted using ethanol and further purified by organic solvents. The pigment extract showed absorbance with a UV-Vis spectrophotometer at 535 nm and further characterized using TLC, FTIR and 1H-NMR. A statistical screening procedure was adopted to select the main factors affecting production. Analyses of Plackett- Burman design results demonstrated that peptone, NaCl, and culture volume were the most important independent variables. The near optimum medium contained (g/L): peptone 7, beef extract 5, yeast extract 1, NaCl 10, pH 6, using 25 ml culture volume, 100 ¼l inoculum size and incubation statically for 48 h at 30oC. When this condition was employed, a two fold increase in pigment yield was achieved reaching ~1600.511 mg/l

Biosynthesis, characterization and optimization of TiO2 nanoparticles by novel marine halophilic Halomonas sp. RAM2: application of natural dye-sensitized solar cells

Abstract Background Metal oxide nanoparticles (NPs) are becoming valuable due to their novel applications. The green synthesis of TiO2 NPs is more popular as a flexible and eco-friendly method compared to traditional chemical synthesis methods. TiO2 NPs are the most commonly used semiconductor in dye-sensitized solar cells (DSSCs). Results The biogenic TiO2 NPs were produced extracellularly by the marine halophilic bacterium Halomonas sp. RAM2. Response surface methodology (RSM) was used to optimize the biosynthesis process, resulting in a starting TiO2 concentration of 0.031 M and a pH of 5 for 92 min (⁓15 nm). TiO2 NPs were well-characterized after the calcination process at different temperatures of 500, 600, 700 and 800 °C. Anatase TiO2 NPs (calcined at 500 °C) with a smaller surface area and a wider bandgap were nominated for use in natural dye-sensitized solar cells (NDSSCs). The natural dye used as a photosensitizer is a mixture of three carotenoids extracted from the marine bacterium Kocuria sp. RAM1. NDSSCs were evaluated under standard illumination. After optimization of the counter electrode, NDSSCBio(10) (10 layers) demonstrated the highest photoelectric conversion efficiency (η) of 0.44%, which was almost as good as NDSSCP25 (0.55%). Conclusion The obtained results confirmed the successful green synthesis of TiO2 NPs and suggested a novel use in combination with bacterial carotenoids in DSSC fabrication, which represents an initial step for further efficiency enhancement studies

Effects of pre-operative isolation on postoperative pulmonary complications after elective surgery: an international prospective cohort study an international prospective cohort study

We aimed to determine the impact of pre-operative isolation on postoperative pulmonary complications after elective surgery during the global SARS-CoV-2 pandemic. We performed an international prospective cohort study including patients undergoing elective surgery in October 2020. Isolation was defined as the period before surgery during which patients did not leave their house or receive visitors from outside their household. The primary outcome was postoperative pulmonary complications, adjusted in multivariable models for measured confounders. Pre-defined sub-group analyses were performed for the primary outcome. A total of 96,454 patients from 114 countries were included and overall, 26,948 (27.9%) patients isolated before surgery. Postoperative pulmonary complications were recorded in 1947 (2.0%) patients of which 227 (11.7%) were associated with SARS-CoV-2 infection. Patients who isolated pre-operatively were older, had more respiratory comorbidities and were more commonly from areas of high SARS-CoV-2 incidence and high-income countries. Although the overall rates of postoperative pulmonary complications were similar in those that isolated and those that did not (2.1% vs 2.0%, respectively), isolation was associated with higher rates of postoperative pulmonary complications after adjustment (adjusted OR 1.20, 95%CI 1.05–1.36, p = 0.005). Sensitivity analyses revealed no further differences when patients were categorised by: pre-operative testing; use of COVID-19-free pathways; or community SARS-CoV-2 prevalence. The rate of postoperative pulmonary complications increased with periods of isolation longer than 3 days, with an OR (95%CI) at 4–7 days or ≥ 8 days of 1.25 (1.04–1.48), p = 0.015 and 1.31 (1.11–1.55), p = 0.001, respectively. Isolation before elective surgery might be associated with a small but clinically important increased risk of postoperative pulmonary complications. Longer periods of isolation showed no reduction in the risk of postoperative pulmonary complications. These findings have significant implications for global provision of elective surgical care. We aimed to determine the impact of pre-operative isolation on postoperative pulmonary complications after elective surgery during the global SARS-CoV-2 pandemic. We performed an international prospective cohort study including patients undergoing elective surgery in October 2020. Isolation was defined as the period before surgery during which patients did not leave their house or receive visitors from outside their household. The primary outcome was postoperative pulmonary complications, adjusted in multivariable models for measured confounders. Pre-defined sub-group analyses were performed for the primary outcome. A total of 96,454 patients from 114 countries were included and overall, 26,948 (27.9%) patients isolated before surgery. Postoperative pulmonary complications were recorded in 1947 (2.0%) patients of which 227 (11.7%) were associated with SARS-CoV-2 infection. Patients who isolated pre-operatively were older, had more respiratory comorbidities and were more commonly from areas of high SARS-CoV-2 incidence and high-income countries. Although the overall rates of postoperative pulmonary complications were similar in those that isolated and those that did not (2.1% vs 2.0%, respectively), isolation was associated with higher rates of postoperative pulmonary complications after adjustment (adjusted OR 1.20, 95%CI 1.05–1.36, p = 0.005). Sensitivity analyses revealed no further differences when patients were categorised by: pre-operative testing; use of COVID-19-free pathways; or community SARS-CoV-2 prevalence. The rate of postoperative pulmonary complications increased with periods of isolation longer than 3 days, with an OR (95%CI) at 4–7 days or ≥ 8 days of 1.25 (1.04–1.48), p = 0.015 and 1.31 (1.11–1.55), p = 0.001, respectively. Isolation before elective surgery might be associated with a small but clinically important increased risk of postoperative pulmonary complications. Longer periods of isolation showed no reduction in the risk of postoperative pulmonary complications. These findings have significant implications for global provision of elective surgical care