A study on Inhibitory Effects of Titanium Dioxide Nanoparticles and its Photocatalytic Type on Staphylococcus aureus, Escherichia coli and Aspergillus flavus

Backgrounds and Objectives: Photocatalyst titanium dioxide nanoparticles can oxidize organic and inorganic compounds of microorganisms in aqueous solutions after exposure to UV light. In the present study, the inhibitory effect of titanium dioxide and its photocatalyst type on Aspergillus flavus, Escherichia coli and Staphylococcus aureus is investigated. Materials and Methods: Toxicogenic strains of Staphylococcus aureus, Escherichia coli and Aspergillus flavus were cultured in their selective media and two groups of samples both included three different concentrations of nanoparticles (0.1, 0.5 and 1 g l-1) and two control samples without any nanoparticles were considered. The first category of samples was placed on the shaker for 20 min, and the second category was irradiated by a UV lamp while shaking for 20, 40 and 60 min on a rotary shaker. Thereafter, they were cultured by using pour plate method in agar and after incubation the colonies were counted. Results and Conclusion: Based on obtained results the photocatalyst titanium dioxide had an inhibitory effect at concentration of 1 g l-1 at the highest timeframe (60 min). In addition, the test variables i.e. the type of bacteria, concentration of nanoparticles and time had a significant effect on the growth inhibition of microorganisms. Regarding the economic aspects of contamination control and its importance in dairy products, application of photocatalystic nanoparticles of titanium dioxide is recommended.

Influencing factors on single-cell protein production by submerged fermentation: A review

Since more than twenty years ago, some species of bacteria and fungi have been used to produce protein biomass or single-cell protein (SCP), with inexpensive feedstock and wastes being used as their sources of carbon and energy. The role of SCP as a safe food and feed is being highlighted more because of the worldwide protein scarcity. Even though SCP has been successfully commercialized in the UK for decades, study of optimal fermentation conditions, various potential substrates, and a broad range of microorganisms is still being pursued by many researchers. In this article, commonly used methods for the production of SCP and different fermentation systems are briefly reviewed, with submerged fermentation being highlighted as a more commonly used method. Emphasis is given to the effect of influencing factors on the biomass yield and productivity in an effort to provide a comprehensive review for researchers in related fields of interest.How to cite: Reihani SFS, Khosravi-Darani K. Influencing factors on single cell protein production by submerged fermentation: A review. Electron J Biotechnol 2019;37. https://doi.org/10.1016/j.ejbt.2018.11.005. Keywords: Aeration, Agricultural waste, Algae, Bacteria, Biomass, Fermentation condition, Fungi, Population growth, Poverty, Protein demand, Single-cell protein, Submerged fermentatio

A study on Inhibitory Effects of Titanium Dioxide Nanoparticles and its Photocatalytic Type on Staphylococcus aureus, Escherichia coli and Aspergillus flavus

Backgrounds and Objectives: Photocatalyst titanium dioxide nanoparticles can oxidize organic and inorganic compounds of microorganisms in aqueous solutions after exposure to UV light. In the present study, the inhibitory effect of titanium dioxide and its photocatalyst type on Aspergillus flavus, Escherichia coli and Staphylococcus aureus is investigated. Materials and Methods: Toxicogenic strains of Staphylococcus aureus, Escherichia coli and Aspergillus flavus were cultured in their selective media and two groups of samples both included three different concentrations of nanoparticles (0.1, 0.5 and 1 g l-1) and two control samples without any nanoparticles were considered. The first category of samples was placed on the shaker for 20 min, and the second category was irradiated by a UV lamp while shaking for 20, 40 and 60 min on a rotary shaker. Thereafter, they were cultured by using pour plate method in agar and after incubation the colonies were counted. Results and Conclusion: Based on obtained results the photocatalyst titanium dioxide had an inhibitory effect at concentration of 1 g l-1 at the highest timeframe (60 min). In addition, the test variables i.e. the type of bacteria, concentration of nanoparticles and time had a significant effect on the growth inhibition of microorganisms. Regarding the economic aspects of contamination control and its importance in dairy products, application of photocatalystic nanoparticles of titanium dioxide is recommended. </p