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Although biosurfactants have great advantages over chemical surfactants, their wider industrial applications have been constrained by their relatively high production cost. Using renewable, sustainable and cheap substrates such as different industrial by-products and wastes maybe decrease biosurfactant production costs. Since in different countries, there are a variety of by-products and wastes so use of these substrates rely on their types and concentrations in countries. In addition to hydrocarbon compounds, molasses has been considered as a dominant by-product in Iran. In this study, among 16 crude oil degrading isolates, strain Pseudomonas aeruginosa ZN was selected as an efficient biosurfactant producer by screening methods for detection of biosurfactant producing bacteria. For investigation of molasses concentrations effect on bacterial growth and biosurfactant production, a wide range of molasses concentrations from 2-12% (v/v) were used. This strain was able to grow and produce biosurfactant in all range of molasses concentrations while the best concentrations were 4-6%. Also, at the optimum molasses concentration, reduction of surface tension from 70 to 32-34 mN/m was observed. The concnetrations more than these values decreased the growth and production process. Acid precipitation and solvent extract (ethyl acetate: hexane) methods were carried out for recovery of biosurfactant from the culture broth, then results of spraying on developed TLC and staining fermentation broth without bacterial cells showed the two produced biosurfactants were glycolipid.

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Gold nanoparticles (GNPs) with unique optical properties, such as easy operation and visualized assay, have a great ability to detect different types of analytes. Today, the use of gold nanoparticles has wide applications in the field of medicine and biotechnology, including the detection of microorganisms that cause contamination in water, air and food and it is considered a suitable alternative for chemical and physical methods. New technologies in the design of biosensors based on GNPs provide the ability to identify biological compounds accurately and quickly. One of these technologies is a detection sensor based on surface plasmon resonance (SPR), which based on its optical properties, is capable of very sensitive and specific measurement of biomolecule interactions without time delay. This technology can quantify in a short time the properties of biomolecular mediators (such as oligonucleotides, proteins and bacteria) on the surface, including reaction speed, tendency and concentration of surface mediators. In this review, while investigating the surface plasmon properties of gold nanoparticles, the simple diagnostic applications of gold nanoparticles based on the localized surface plasmon (LSPR) method and detection in biomedicine.