Enhanced desulfurization activity in protoplast transformed Rhodococcus erythropolis

Petro-chemically derived fuels may contain a range of organosulfur compounds that produce sulfur dioxide when combusted, culminating in atmospheric and soil pollution. Sulfur constituents include thiophenes, such as Benzothiophene and Dibenzothiaphene(DPT), with the latter often used as a model for the isolation of bacteria capable of selective removal of sulfur for potential use in the desulfurization of fuel oils. A bacterium capable of desulfuring DBT was isolated from a gasoline-contaminated soil in Isfahan,Iran. Desulfurization employs the 4S metabolic pathway that leads to the production of 2-hydroxybiphenyl (HBP) as an end product. Biochemical analyses and 16S rRNA gene sequencing identified the organism as Rhodococcus erythropolis(strain R1) with a rapid capability to desulfurize DBT when using it as its sole sulfur source. Plasmids from R.erythropolis strain R1 (HBP-positive) were used to produce a stable desulfurizing mutant (mut23) of a HBP-negative strain by polyethylene glycol (PEG)-mediated protoplast transformation. R.erythropolis strain R1 and transformed Rhodococcus strain (mut23) were able to degrade 100% of the original DBT after 72h. However, mut23 desulfurized DBT and produced HBP more efficiently than wild type R1 strain

Enhanced desulfurization activity in protoplast transformed Rhodococcus erythropolis

Petro-chemically derived fuels may contain a range of organosulfur compounds that produce sulfur dioxide when combusted, culminating in atmospheric and soil pollution. Sulfur constituents include thiophenes, such as Benzothiophene and Dibenzothiaphene(DPT), with the latter often used as a model for the isolation of bacteria capable of selective removal of sulfur for potential use in the desulfurization of fuel oils. A bacterium capable of desulfuring DBT was isolated from a gasoline-contaminated soil in Isfahan,Iran. Desulfurization employs the 4S metabolic pathway that leads to the production of 2-hydroxybiphenyl (HBP) as an end product. Biochemical analyses and 16S rRNA gene sequencing identified the organism as Rhodococcus erythropolis(strain R1) with a rapid capability to desulfurize DBT when using it as its sole sulfur source. Plasmids from R.erythropolis strain R1 (HBP-positive) were used to produce a stable desulfurizing mutant (mut23) of a HBP-negative strain by polyethylene glycol (PEG)-mediated protoplast transformation. R.erythropolis strain R1 and transformed Rhodococcus strain (mut23) were able to degrade 100% of the original DBT after 72h. However, mut23 desulfurized DBT and produced HBP more efficiently than wild type R1 strain

Antimicrobial Effect of Copper Oxide Nanoparticles on Some Oral Bacteria and Candida Species

Statement of Problem: Acid producing bacteria including Streptococcus mutans and lactobacilli cause tooth demineralization and lead to tooth decay. Also, oral colonization of the species of Candida has been reported in many studies that are resistant to antifungal agents. Objectives: In this study, antibacterial and antifungal effects of nano-CuO were studied against some oral bacteria and yeast fungi. Materials and Methods: The minimum inhibitory concentrations (MICs) of copper oxide nanoparticles (CuO NPs) for oral bacterial and fungal test strains were determined in 96-well microtiter plate technique. The agar diffusion test (ADT) was employed to assess the antifungal properties of nystatin. Results: The MIC50 value of CuO NPs was determined at the range of 1–10 µg/ml for S. mutans, < 1 µg/ml for L. acidophilus, and 10 µg/ml for L. casei. Higher concentrations of CuO NPs (100-1000 µg/ml) were effective on the bacterial cell growth, resulting in 100% reduction in the optical density in TSB medium. The cells of Candida albicans, C. krusei and C. glabrata were treated with CuO NPs and the results showed a decrease in fungal growth at a concentration of 1-1000 µg/ml in TSB medium. The MIC50 value of CuO NPs was determined 1000 µg/ml for three species of Candida. The diameter of growth inhibition zones of 1100 µg/ml nystatin was obtained 15-21 mm for clinical isolates of three species of Candida. Conclusions: With respect to the potential bactericidal activity of CuO NPs on various cariogenic bacteria examined in this study, these NPs could be introduce as a candidate control agent for preventing dental caries or dental infections. In our study, on the other hand, Nano copper oxide had a weak effect on the candida species

Enhancement of biomass and total carotenoid content of a UV-resistant strain of Dietzia maris in response to different carbon and nitrogen sources

In the present study, the effect of various fermentation media on the production of carotenoid pigment in a radiation-resistant strain of Dietzia maris was reported. The biomass and pigment production of this strain was evaluated using various sources of carbon and nitrogen as well as different concentrations of whey medium. The antioxidant and cytotoxic activities of the extracted pigment were also determined using ferric reducing antioxidant power (FRAP), 2,2-diphenyl-1-picrylhydrazyl radicals (DPPH), and MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide) assays. The antibacterial activity of the carotenoid pigment was also evaluated. All carbon sources increased the pigment production of D. maris in the following order: glucose > raffinose = starch = xylose> sorbitol > sucrose. However, only glucose, xylose, and sorbitol significantly increased the microbial biomass as compared to the control. Moreover, all organic nitrogen sources and ammonium sulfate enhanced the pigment production of the studied strain by approximately 6–9 folds. The free radical scavenging capacity and FRAP of the D. maris carotenoid extract were reported as half-maximal effective concentration or EC50= 3.30 mg/ml and EC50 =28.46 μg/ml, respectively. The maximum amount of biomass and carotenoid pigment produced by D. maris was obtained in the fermentation medium containing 1 g/l glucose and 1 g/l yeast extract (18 mg/l). This strain can be considered as a promising biocatalyst for the commercial production of natural carotenoids due to its antioxidant capacity and noncytotoxic activity

Efficacy of polyextremophilic Aeribacillus pallidus on bioprocessing of beet vinasse derived from ethanol industries

This work aimed to evaluate the applicability of Aeribacillus pallidus for the aerobic treatment of the concentrated beet vinasse with high chemical oxygen demand (COD 685 g.L−1) that is defined as an environmental pollutant. This bacterium is a polyextremophilic strain and grow aerobically up to 7.5% vinasse at high temperature (50 °C). In the bioreactor and under controlled conditions, A. pallidus reduced the soluble COD content of 5% vinasse up to 27% during 48 h and utilized glucose and glycerol, completely. Furthermore, a reduction of manganese, copper, aluminum, and nickel concentrations was observed in the treated vinasse with A. pallidus. The obtained results make this strain as an appropriate alternative to be used for the aerobic bioprocessing of the vinasse. © 2020 The Author(s

Mussel inspired bacterial denitrification of water using fractal patterns of polydopamine

© 2019 Elsevier Ltd Nitrate is currently one of the most significant causes of water pollution in many parts of the world due to its detrimental effects on humans and the environment. The purpose of this study was to find a novel immobilization method based on bacterial adsorption to adhesive coating material, for use in water denitrification. The fractal formation capability of polydopamine (PDA) allowed coating of the surface of in-house asymmetric polyethersulfone (PES) beads (1.65–2.35 mm in diameter), and immobilizing the denitrifying bacteria Pseudomonas stutzeri with noticeable denitrification potential, on the surface of hyper-branched PDA coated beads. For surface characterization, SEM, wettability measurement, and ATR-FTIR spectroscopy were performed. Nitrate and nitrite concentrations were measured by APHA standard method 4500-NO3−-B and a colourimetric method using two reagents respectively. The effects of temperature, pH and different carbon sources (Acetic acid, methanol, and ethanol) on the denitrification process were also investigated. The results revealed that the bacterial immobilization on PES surface with fractal patterns of PDA (with fractal dimension (Df) value of 1.57) was successful, and the optimum parameters for nitrate removal were established as 25 °C, pH = 8, and 420 mg/L ethanol as the carbon source. Finally, this research showed that under the optimum conditions the immobilized bacteria exhibited 100 % removal efficiency for 28 mg of NO3–N in 22 h (removal rate: 8.06 mg NO3-N/h/mg biomass of bacteria). We found that the immobilization of bacteria on the PDA coated beads is practicable and that the denitrification rate is adequate

Microbial diversity in the hypersaline Lake Meyghan, Iran

Lake Meyghan is one of the largest and commercially most important salt lakes in Iran. Despite its inland location and high altitude, Lake Meyghan has a thalassohaline salt composition suggesting a marine origin. Inputs of fresh water by rivers and rainfall formed various basins characterized by different salinities. We analyzed the microbial community composition of three basins by isolation and culturing of microorganisms and by analysis of the metagenome. The basins that were investigated comprised a green ~50 g kg−1 salinity brine, a red ~180 g kg−1 salinity brine and a white ~300 g kg−1 salinity brine. Using different growth media, 57 strains of Bacteria and 48 strains of Archaea were isolated. Two bacterial isolates represent potential novel species with less than 96% 16S rRNA gene sequence identity to known species. Abundant isolates were also well represented in the metagenome. Bacteria dominated the low salinity brine, with Alteromonadales (Gammaproteobacteria) as a particularly important taxon, whereas the high salinity brines were dominated by haloarchaea. Although the brines of Lake Meyghan differ in geochemical composition, their ecosystem function appears largely conserved amongst each other while being driven by different microbial communities