4 research outputs found
Investigating the effects of various additives on surface activity and emulsification index of biosurfactant resulting from broth media of Bacillus subtilis PTCC 1023
Surfactants are amphipathic molecules which reduce surface tension and are widely used in
pharmaceutical, cosmetic and food industries. In the present study, the production of biosurfactant by
Bacillus subtilis PTCC 1023 was studied. B. subtilis was grown in the nutrient broth medium and
biosurfactant production was evaluated by measuring the surface tension and emulsification index (E24)
each 24 h. The bacterium’s biosurfactant production was investigated in different status with variable
factors such as incubation time, temperature, aeration rate and presence of several additives. Then the
best fermentation condition was investigated for maximum biosurfactant production and finally
biosurfactant identity was investigated using some chemical and spectroscopy methods. The maximum
biosurfactant production by B. subtilis PTCC 1023 was obtained when it was grown in brain-heart broth
medium containing FeSO4 (4×10-3 M), MnSO4 (1.3×10-3 M), starch (4%) and castor oil (4%) which
incubated in a 300 rpm rotary shaker at 30°C for 24 h. Lipopepetide natures in this biosurfactant was
confirmed by biochemical and spectroscopic methods
Investigation of cellular hydrophobicity and surface activity effects of biosynthesed biosurfactant from broth media of PTCC 1561
Biosurfactants as surface active molecules that are synthesized by microorganisms. These substances
include many advantages in comparison with chemical surfactants. For instance they have lower
toxicity, higher biodegradability, better environmental compatibility, higher foaming activity, and
specific activity at extreme temperatures, pH ranges, and the ability to be synthesized from renewable
feed stocksin. In this study, the production of biosurfactant, produced by PTCC 1561 was studied. This
bactrium was grown in a nutrient broth medium and the production of biosurfactant was evaluated by
the surface tension and emulisification index (E24), each 24 h. The production of biosurfactant was
studied in different conditions, including time of incubation, temperature, aeration rate and presence of
several additives containing mineral salts and hydrocarbons. Finally, the optimum condition for
production of the biosurfactant was determined and the biosurfactant identity was investigated using
chemical and spectroscopy methods. The maximum biosurfactant production by Pseudomonas
aeruginosa PTCC 1561, was exhibited when it was grown in Brain Hearth Broth medium containing
Fecl3, ZnSO4, FeSO4, starch and olive oil incubated in a 200 rpm shaker incubator at 37°C for 24 h . The
structure of produced biosurfactant sugar-lipid was confirmed by chemical and spectroscopy methods
Antitumor and antibacterial activity of four fractions from Heracleum persicum Desf. and Cinnamomum zeylanicum Blume
At the present study tumor inhibition and antibacterial activity of the essential oils of Heracleum
persicum and Cinnamomum zeylanicum was investigated. Methanol and petroleum ether were
extracted from C. zeylanicum by potato disk method. These fractions showed cytotoxic effects in brine
shrimp lethality assay (BSL). The authors found both H. persicum (57.16%) and C. zeylanicum (72.90%)
had inhibition effects on Agrobacterium tumefaciens which induced crown gall tumor on potato disk.
These oils also exhibited antitumor activity where IC50 was applied and the values were 2.24 and 1.20
mg/mL, respectively, for H. persicum and C. zeylanicum. C. zeylanicum also inhibited the growth of all
tested Gram- positive and Gram-negative strains. In all, the findings of the present study completely
correspond to the results obtained in brine shrimp lethality
Folding Thermodynamics of the Hybrid-1 Type Intramolecular Human Telomeric GQuadruplex
Guanine-rich DNA sequences that may form
G-quadruplexes are located in strategic DNA loci with
the ability to regulate biological events. G-quadruplexes
have been under intensive scrutiny owing to their potential
to serve as novel drug targets in emerging anticancer
strategies. Thermodynamic characterization of
G-quadruplexes is an important and necessary step in
developing predictive algorithms for evaluating the conformational
preferences of G-rich sequences in the presence
or the absence of their complementary C-rich
strands. We use a combination of spectroscopic, calorimetric,
and volumetric techniques to characterize the
folding/unfolding transitions of the 26-meric human telomeric
sequence d[A3G3(T2AG3)3A2]. In the presence of
K1 ions, the latter adopts the hybrid-1 G-quadruplex
conformation, a tightly packed structure with an unusually
small number of solvent-exposed atomic groups. The
K1-induced folding of the G-quadruplex at room temperature
is a slow process that involves significant accumulation
of an intermediate at the early stages of the
transition. The G-quadruplex state of the oligomeric
sequence is characterized by a larger volume and compressibility
and a smaller expansibility than the coil state.
These results are in qualitative agreement with each other
all suggesting significant dehydration to accompany the
G-quadruplex formation. Based on our volume data,
432619 water molecules become released to the bulk
upon the G-quadruplex formation. This large number is
consistent with a picture in which DNA dehydration is
not limited to water molecules in direct contact with the
regions that become buried but involves a general
decrease in solute–solvent interactions all over the surface
of the folded structure. VC 2013 Wiley Periodicals, Inc.
Biopolymers 101: 216–227, 2014.
Keywords: G-quadruplexes; conformational transitions;
volume; compressibility; expansibilit