Abstract: Kefir is a traditional fermented refreshing beverage which is known for its valuable and beneficial properties for human health. Mainly yeast species, lactic acid bacteria (LAB) strains and fewer acetic acid bacteria strains live together in a natural matrix named “kefir grain”, which is formed from various proteins and polysaccharides. Different microbial species live together in slimy kefir grain and it has been thought that synergetic effect could take place between microorganisms, which belong to different genera and species. In this research, yeast and LAB were isolated from kefir samples obtained from Uludag University Food Engineering Department. The cell morphology of isolates was screened by microscopic examination. Gram reactions of bacteria isolates were determined by Gram staining method, and as well catalase activity was examined. After observing the microscopic/morphological and physical, enzymatic properties of all isolates, they were divided into the groups as LAB and/or yeast according to their physicochemical responses to the applied examinations. As part of this research, the antagonistic/synergistic efficacy of the identified five LAB and five yeast strains to each other were determined individually by disk diffusion method. The antagonistic or synergistic effect is one of the most important properties in a co-culture system that different microorganisms are living together. The synergistic effect should be promoted, whereas the antagonistic effect is prevented to provide effective culture for fermentation of kefir. The aim of this study was to determine microbial interactions between identified yeast and LAB strains, and whether their effect is antagonistic or synergistic. Thus, if there is a strain which inhibits or retards the growth of other strains found in Kefir microflora, this circumstance shows the presence of antagonistic effect in the medium. Such negative influence should be prevented, whereas the microorganisms which have synergistic effect on each other should be promoted by combining them in kefir grain. Standardisation is the most desired property for industrial production. Each microorganism found in the microbial flora of a kefir grain should be identified individually. The members of the microbial community found in the glue-like kefir grain may be redesigned as a starter culture regarding efficacy of each microorganism to another in kefir processing. The main aim of this research was to shed light on more effective production of kefir grain and to contribute a standardisation of kefir processing in the food industry.
Abstract: As 3D video is explored as a hot research topic in the last few decades, free-viewpoint TV (FTV) is no doubt a promising field for its better visual experience and incomparable interactivity. View synthesis is obviously a crucial technology for FTV; it enables to render images in unlimited numbers of virtual viewpoints with the information from limited numbers of reference view. In this paper, a novel hybrid synthesis framework is proposed and blending priority is explored. In contrast to the commonly used View Synthesis Reference Software (VSRS), the presented synthesis process is driven in consideration of the temporal correlation of image sequences. The temporal correlations will be exploited to produce fine synthesis results even near the foreground boundaries. As for the blending priority, this scheme proposed that one of the two reference views is selected to be the main reference view based on the distance between the reference views and virtual view, another view is chosen as the auxiliary viewpoint, just assist to fill the hole pixel with the help of background information. Significant improvement of the proposed approach over the state-of –the-art pixel-based virtual view synthesis method is presented, the results of the experiments show that subjective gains can be observed, and objective PSNR average gains range from 0.5 to 1.3 dB, while SSIM average gains range from 0.01 to 0.05.
Abstract: In this study, antimicrobial effect of Greek clover was determined with usage of MIC (minimum inhibition concentration) and agar diffusion method. Moreover, pH, water activity and microbial change were determined during storage of fenugreek paste. At first part of our study, microbial load of spices was evaluated. Two different fenugreek pastes were produced with mixing of Greek clover, spices, garlic and water. Fenugreek pastes were stored at 4 °C. At the second part, antimicrobial effect of Greek clover was determined on Escherichia coli, Staphylococcus aureus, Bacillus subtilis, Debaryomyces hansenii, Aspergillus parasiticus, Candida rugosa, Mucor spp., when the concentrations of Greek clover were 8%, 12% and 16%. According to the results obtained, mould growth was determined at 15th and 30th days of storage in first and second fenugreek samples, respectively. Greek clover showed only antifungal effect on Aspergillus parasiticus at previously mentioned concentrations.
Abstract: Medicinal plants are now gaining attractiveness in
treatment of bacterial infections and food preservation. The objective
of this study was to assess antibacterial activity of some medicinal
plants on pathogenic bacteria. Screening of antibacterial activity of
aqueous and methanol extracts of some plants: Jojoba, Ginger, Sage,
Thyme and Clove against Bacillus cereus, Salmonella typhimurium,
Staphylococcus aureus, Clostridium perfringens and Escherichia coli
were investigated. Antibacterial activity was performed by agar
diffusion and disc diffusion method. Jatropha, Jojoba, Clove and
Ginger extracts showed notable bacterial activity in the first
screening step then selected to be tested against Bacillus cereus
(Gram+), Staphylococcus aureus (Gram+) and Salmonella
typhimurium (Gram−) and their effect was compared using
antibiotics as control. Screening results showed potential antibacterial
activity of the tested plant extracts against the screened bacterial
strains. It was found that methanol extracts exhibited higher
antibacterial activity than aqueous extracts. Methanol extract of
Jatropha showed the highest inhibition zone against Staphylococcus
aureus (Gram+) with 24.00 mm diameter, compared to the other
plant extracts followed by clove. Meanwhile, the inhibition zones of
methanol extracts of Jojoba and Ginger were the same (12mm).The
Gram-positive bacteria were found to be more sensitive to aqueous
and methanol extracts than Gram-negative bacteria.
Abstract: The present study was done to evaluate the presence
of tetracycline resistance genes in Lactococcus garvieae isolated
from cultured rainbow trout, West Iran. The isolates were examined
for antimicrobial resistance using disc diffusion method. Of the 49
strains tested, 19 were resistant to tetracycline (38.7%), 32 to
enrofloxacin (65.3%), 21 to erythromycin (42.8%), 20 to
chloramphenicol and trimetoprim-sulfamethoxazole (40.8%). The
strains were then characterized for their genotypic resistance profiles.
The results revealed that all 49 isolates contained at least one of the
tetracycline resistance genes. Tet (A) was found in 89.4% of
tetracycline resistant isolates and the frequency of other gene were as
follows: tet (E) 42.1%, tet (B) 47.3%, tet (D) 15.7%, tet (L) 26.3%,
tet (K) 52.6%, tet (G) 36.8%, tet (34) 21%, tet (S) 63.1%, tet (C)
57.8%, tet (M) 73.6%, tet (O) 42.1%. The results revealed high levels
of antibiotic resistance in L. garvieae strains which is a potential
danger for trout culture as well as for public health.
Abstract: Alcohol and water extracts of Cymbopogon citratus
was investigated for anti-bacterial properties and phytochemical
constituents. The extract was screened against four gram-negative
bacteria Escherichia coli, Klebsiella pneumoniae, Pseudomonas
aeruginosa, Proteus vulgaris) and two grampositive bacteria Bacillus
subtilis and Staphylococcus aureus at four different concentrations
(1:1, 1:5, 1:10 and 1:20) using disc diffusion method. The antibacterial
examination was by disc diffusion techniques, while the
photochemical constituents were investigated using standard
chemical methods. Results showed that the extracts inhibited the
growth of standard and local strains of the organisms used. The
treatments were significantly different (P = 0.05). The minimum
inhibitory concentration of the extracts against the tested
microorganisms ranged between 150mg/ml and 50mg/ml. The
alcohol extracts were found to be generally more effective than the
water extract. The photochemical analysis revealed the presence of
alkaloids and phenol but absence of cardiac and cyanogenic
glycosides. The presence of alkaloid and phenols were inferred as
being responsible for the anti-bacterial properties of the extracts.
Abstract: The antimicrobial, antiplasmid and cytotoxic activities of marine algae Halimeda opuntia and Sarconema filiforme were investigated. Antimicrobial bioassay against some human pathogenic bacteria and yeast were conducted using disc diffusion method. Halimeda extract exhibited antibacterial activity against six species of microrganisms, with significant inhibition against Staphylococcus aureus. While Sarconema extract was better potent as antifungal against Candida albicans. Comparative antibacterial studies showed that Halimeda extract showed equivalent or better activity as compared with commercial antibiotic when tested against Staphylococcus aureus. Further tests conducted using dilution method showed both extracts as having bacteriostatic mode of action against the tested microorganisms. Methanol extract of two species showed significant cytotoxicity (LC50
Abstract: Antibacterial activity of Plumeria alba (Frangipani)
petals methanolic extracts were evaluated against Escherichia coli,
Proteus vulgaris,Staphylococcus aureus, Klebsiella pneumoniae,
Pseudomonas aeruginosa, Staphylococcus saprophyticus,
Enterococcus faecalis and Serratia marcescens by using disk
diffusion method. Concentration extracts (80 %) showed the highest
inhibition zone towards Escherichia coli (14.3 mm). Frangipani
extract also showed high antibacterial activity against
Staphylococcus saprophyticus, Proteus vulgaris and Serratia
marcescens, but not more than the zones of the positive control used.
Comparison between two broad specrum antibiotics to frangipani
extracts showed that the 80 % concentration extracts produce the
same zone of inhibition as Streptomycin. Frangipani extracts showed
no bacterial activity towards Klebsiella pneumoniae, Pseudomonas
aeruginosa and Enterococcus faecalis. There are differences in the
sensitivity of different bacteria to frangipani extracts, suggesting that
frangipani-s potency varies between these bacteria. The present
results indicate that frangipani showed significant antibacterial
activity especially to Escherichia coli.
Abstract: The aim of the study was to investigate phytochemical
properties, antimicrobial activity and cytotoxicity of Aloe vera. The
phytochemical screening of the extracts of leaves of A. vera revealed
the presence of bioactive compounds such as alkaloids, tannins,
flavonoids phenolic compounds, and etc. with absence of cyanogenic
glycosides. Three different solvents such as methanol, ethanol and
Di-Methyl sulfoxide were used to screen the antimicrobial activity of
A. vera leaves against four human clinical pathogens by agar well
diffusion method. The maximum antibacterial activities were
observed in methanol extract followed by ethanol and Di-Methyl
sulfoxide. It was also found that remarkable antibacterial activities
with methanolic and ethanolic extracts of A. vera compared with the
standard antibiotic, tetracycline that was not active against E. coli
and S. boydii and supported the view that A. vera is a potent
antimicrobial agent compared with the conventional antibiotic.
Moreover, the brine shrimps (Artemia salina) toxicity test exhibited
LC50 value was 569.52 ppm. The resulting data indicated that the A.
vera plant have less toxic effects on brine shrimp. Hence, it is
signified that Aloe vera plant extract is safe to be used as an
antimicrobial agent.
Abstract: The present research was designed to investigate the
anti-microbial activity of aristolochic acid from the root of
Aristolochia bracteata. From the methanolic & ethyl extract extracts
of Aristolochia bracteata aristolochic acid I was isolated and
conformed through IR, NMR & MS. The percentage purity of
aristolochic acid I was determined by UV & HPLC method. Antibacterial
activity of extracts of Aristolochia bracteata and the
isolated compound was determined by disc diffusion method. The
results reveled that the isolated aristolochic acid from methanolic
extract was more pure than the compound from ethyl acetate extract.
The various extracts (500μg/disc) of Aristolochia bracteata showed
moderate antibacterial activity with the average zone of inhibition of
7-18 mm by disc diffusion method. Among the extracts, ethyl acetate
& methanol extracts were shown good anti-microbial activity and the
growth of E.coli (18 mm) was strongly inhibited. Microbial assay of
isolated compound (Aristolochic acid I) from ethyl acetate &
methanol extracts were shown good antimicrobial activity and the
zone of inhibition of both at higher concentration 50 μg/ml was
similar with the standard aristolochic acid. It may be concluded that
the isolated compound of aristolochic acid I has good anti-bacterial
activity.