sharareh harirchi

Fossil fuels are the main sources of water, soil, and air pollution that threaten human life and other organisms on Earth. Nowadays, the climate change and pollution are critical issues; however, many countries still use polluting fossil fuels. Therefore, finding alternative and clean fuels is a concern for many environmental activists and scientists. One of these alternative fuels is ethanol, which ignites cleaner due to its higher hydroxyl groups and lack of sulfur and nitrogen in its formula. Ethanol can be produced both chemically and biologically. Till now, four generations of bioethanol have been introduced. In the second generation, lignocellulosic materials are used as the main source for bioethanol production. These materials are frequently found in plant biomasses and agricultural residues, which are inexpensive and environmentally sustainable. Therefore, it is of importance to improve the production process and find novel techniques that increase final yields and process efficacy. In this study, the structural properties of lignocellulosic materials, pretreatment techniques, the second-generation bioethanol production process, and the effective bacterial and fungal strains in this procedure are investigated.

This review study is a narrative review in which a logical search approach was selected. For data analysis, a comparative approach between the different methods was expressed in each section.

Among four bioethanol generations, the second generation has received remarkable attention due to its non-competition with human food and its industrial potential rather than other generations. Therefore, it is of particular significance to improve the production process of bioethanol second generation. A deep understanding of lignocellulosic components, pretreatment methods optimization, and increasing hydrolysis and fermentation processes efficiency make bioethanol production industrially possible and cost-effective.

However, despite extensive studies to select the most suitable microorganisms during the fermentation stage, Saccharomyces cerevisiae and Zymomonas mobilis are still at the forefront of studies.

Antimicrobial resistance is one of the major characteristics of infectious agents. Silver nanoparticles (AgNPs) have been introduced as novel antibacterial agents in accordance with the traditional treatments. Our purpose of this study was to evaluate the antimicrobial activity of AgNPs on the Pseudomonas aeruginosa (P. aeruginosa) that are resistant to antibiotics.
During a cross-sectional study, we tried to evaluate 20 strains of P. aeruginosa isolated from the urine cultures of patients admitted to the hospital due to urinary tract infections. The AgNPs were commercially purchased. The minimum inhibitory concentration (MIC) of AgNPs in different concentrations was determined by the dilution in wells on bacteria. The antibiotic susceptibility pattern of P. aeruginosa was evaluated by the Kirby-Bauer disk diffusion standard.
Current study indicated that P. aeruginosa were resistant to four types of agents including ampicillin (85%), nitrofurantoin (65%), nalidixic acid (65%), and ciprofloxacin (15%) and result of nanosilver indicated that the most MIC was 100 ppm concentration, and six strains of P. aeruginosa were inhibited by it.
Our study presented a new type of silver nanoparticle and indicated that they can be embedded in bone cement to prevent infections once synthetic conditions are tailored for such applications.