Photocatalytic decolorization of bromothymol blue using biogenic selenium nanoparticles synthesized by terrestrial actinomycete Streptomyces griseobrunneus strain FSHH12

The aim of the present study was to isolate and identify a terrestrial actinomycete bacterial strain capable to produce selenium nanoparticles (Se NPs) followed by purification of the biogenic Se NPs and evaluation of their photocatalytic degradation compared to selenium dioxide. Among 30 actinomycete bacterial strains obtained from environmental soil samples, one isolate (identified as Streptomyces griseobrunneus strain FSHH12 based on the 16S rDNA gene sequence analysis) was selected and used for production of Se NPs. The biologically synthesized Se NPs was consequently purified by an organic–aqueous partitioning system and characterized using scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray, UV–visible spectroscopy, Fourier transform infrared spectroscopy, and X-ray diffraction spectroscopy. The obtained results of photocatalytic degradation of bromothymol blue using the purified Se NPs (64 μg/mL) revealed 62.3% of dye removal under UV illumination (15 W) after 60 min incubation of dye solution

Partial Purification and Characterization of a Thermoalkalophilic Lipase Originated from Bacillus atrophaeus FSHM2 and its Application for Ester Synthesis

A thermoalkalophilic lipase producing bacterial strain, identified as Bacillus atrophaeus FSHM2 using 16S rDNA sequencing analysis was isolated from salty soil and its lipase was partially purified and characterized. The obtained results revealed that glucose, hazelnut oil, urea and calcium ion positively affected the lipase production by increasing the lipolytic activity to 13582.5, 6270, 4442 and 5505 U LG1, respectively compared to that of basal medium (4150 U LG1). The partially purified lipase acted optimally at pH 9 and retained 88.2% of its initial activity after 1 h of incubation at 100°C. A two fold increase in the relative activity of the partially purified lipase was obtained in the presence of 4 M of NaCl. Application of the partially purified lipase for the synthesis of ethyl and methyl valerate in the organic solvent medium (xylene) resulted in 81.6 and 62.4% esterification, respectively, after 24 h of incubation

Thermoalkalophilic lipase from an extremely halophilic bacterial strain <i>Bacillus atrophaeus</i> FSHM2: Purification, biochemical characterization and application

<p>The present study was designed to isolate and identify an extremely halophilic lipase-producing bacterial strain, purify and characterize the related enzyme and evaluate its application for ethyl and methyl valerate synthesis. Among four halophilic isolates, the lipolytic ability of one isolate (identified as <i>Bacillus atrophaeus</i> FSHM2) was confirmed. The enzyme (designated as <i>Ba</i>L) was purified using three sequential steps of ethanol precipitation and dialysis, Q-Sepharose XL anion-exchange chromatography and SP Sepharose cation-exchange chromatography with a final yield of 9.9% and a purification factor of 31.8. The purified <i>Ba</i>L (Mw∼85 kDa) was most active at 70 °C and pH 9 in the presence of 4 M NaCl and retained 58.7% of its initial activity after 150 min of incubation at 80 °C. The enzyme was inhibited by Cd²⁺ (35.6 ± 1.7%) but activated by Ca²⁺ (132.4 ± 2.2%). Evaluation of <i>Ba</i>L's stability in the presence of organic solvents showed that xylene (25%) enhanced the relative activity of the enzyme to 334.2 ± 0.6% after 1 h of incubation. The results of esterification studies using the purified <i>Ba</i>L revealed that maximum ethyl valerate (88.5%) and methyl valerate (67.5%) synthesis occurred in the organic solvent medium (xylene) after 48 h of incubation at 50 °C.</p