Atieh Sadat Razavi; Parisa Tajer Mohammad Ghazvini; javad hamedi
Abstract
Biomineralization of selenium by bacteria not only has the potential to remove toxic selenium oxyanions from the environment, but can also produce nano- scale elemental selenium. In this work, the response surface method (RSM) based on the Box- Behnken design was used for evaluation and optimization ...
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Biomineralization of selenium by bacteria not only has the potential to remove toxic selenium oxyanions from the environment, but can also produce nano- scale elemental selenium. In this work, the response surface method (RSM) based on the Box- Behnken design was used for evaluation and optimization of the different process parameters effect on the bioreduction process of selenate. The proposed second order model with a correlation coefficient R2 = 0.96 appropriately predicted the process behavior and determined the 41.25 percent reduction of selenate by Bacillus sp. Strain TR-6 at 5.24 percent initial bacterial inoculation, process time of 24 h and 3.8 mM concentration of sodium selenate as the optimum condition. Scanning electron microscope (SEM) with the Energy Dispersive X-ray spectroscopy (EDX) confirmed the ability of the selected bacteria to produce selenium nanospheres. Finally, Bacillus sp. Strain TR-6 is determined as a valuable candidate for nano- technologies and selenium biomineralization processes.
Microbiology
Javad Hamedi; Fatemeh Yazdiyan
Abstract
Nisin is the first FDA-approved food preservative produced by Lactococcus lactis at industrial scale. The negative effect of lactic acid produced by metabolism of Lactococcus lactis subsp. lactis, on nisin production, was removed by co-culture of Lactococcus lactis with Yarrowia lipolytica yeast. In ...
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Nisin is the first FDA-approved food preservative produced by Lactococcus lactis at industrial scale. The negative effect of lactic acid produced by metabolism of Lactococcus lactis subsp. lactis, on nisin production, was removed by co-culture of Lactococcus lactis with Yarrowia lipolytica yeast. In the present study, the co-culture of Lactococcus lactis subsp. lactis and Yarrowia lipolyticawas performed for the first time inmolasses-based medium at 30°C, pH 6, 100 rpm, 0.15 vvm was applied in a laboratory scale bioreactor. Nisin production was measured as 920 IU/mL. The results showed that co-culture fermentation increased biomass and nisin production up to 63% and 78%, respectively. Other factors such as extracellular proteolytic activity of the yeast should be taken into consideration, which in turn make the culture nutrients more available to the bacterium.
Sara Mavaddati; Javad Hamedi; Bahman Zeynali
Abstract
The microbiota of breast-fed infants are mainly consists of Bifidobacterium and Lactobacillus. Normal vaginal delivery has an important role in the colonization of beneficial bacteria and proper development of the immune system and gastrointestinal tract in comparison with infants born through cesarean ...
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The microbiota of breast-fed infants are mainly consists of Bifidobacterium and Lactobacillus. Normal vaginal delivery has an important role in the colonization of beneficial bacteria and proper development of the immune system and gastrointestinal tract in comparison with infants born through cesarean section. In this study we examined the effect of microbiota of a 4-month-old breastfeeding infant born with normal vaginal delivery, without history of taking antibiotics and gastrointestinal disorders on the cell viability of two types of cells with different growth features including colon cancer cells (Caco-2) and Unrestricted Somatic Stem Cells (USSCs). After fecal sampling, the microbiota was extracted by ethyl acetate. After removing the solvent, the result of extraction was solved in a few volume of DMSO. The effects at concentrations of 2.5 and 5 µg/ ml on the following cells were determined after 72 hours of incubation using MTT assay. The results showed that the cell viability of USSCs was significantly increased as the concentration elevated. While at the same conditions, the viability of Caco-2 cells was decreased at the higher concentration significantly.
