نشریه دانش زیستی ایران
سال شانزدهم شماره 1 (بهار 1400)

The increasing use of antibiotics and the prevalence of resistant strains have necessitated the use of new antimicrobial drugs. Combination therapy is an effective strategy to combat antibacterial resistance. The aim of this study was to investigate the antibacterial synergistic effect of Origanum vulgare essential oil and silver nanoparticles on gram-positive and gram-negative bacteria. In this study, O. vulgare essential oil was extracted from the plant branch. A colloidal solution of silver nanoparticles with an average particle diameter of 68 nm was purchased. The antibacterial effect of O. vulgare essential oil and silver nanoparticles was investigated alone and then in combination by broth microdilution method and their minimum inhibitory concentration (MIC) against gram-positive and gram-negative bacteria was determined. The bacteria studied were Escherichia coli, Salmonella enterica, Bacillus subtilis and Staphylococcus aureus. Based on the obtained results, the synergistic effect of O. vulgare essential oil and silver nanoparticles had significant antimicrobial effects on all studied bacteria. The results showed that the synergistic effect of O. vulgare essential oil and silver nanoparticles was effective in inhibiting and killing the studied bacteria. And they can be useful in developing new drugs against these bacteria.

Due to the high consumption of amylase, the use of amylase-producing strains and optimizing the production conditions of this enzyme is an efficient way to produce this enzyme. Due to the fact that the amylase gene of Bacillus alkalitelluris has not been identified so far, it is important to achieve stable enzyme production conditions by the bacteria that produce these enzymes. One of the most important methods is to immobilization of the bacteria in suitable support so that the ability of these bacteria to produce enzymes is maintained. In this study, Bacillus alkalitelluris was first cultured in LB broth culture medium containing starch. The bacteria were then immobolized on agar and the amount of enzyme produced was measured using the DNS method. Finally, the amount of enzyme production when re-use stabilized cells in successive cultures was evaluated. According to the results, the bacterium Bacillus alkalitelluris immobilized in agar support is still able to produce alpha-amylase enzyme. Maximum alpha-amylase production was obtained after 24 hours. In addition, the immobilized bacteria remain after 4 times of changing the culture medium and are able to produce amylase enzyme so that up to 72 hours no significant change in enzyme production is observed. Due to the fact that the immobilized of Bacillus alkalitelluris in agar leads to the maintenance of alpha-amylase production capacity, so this method can be used in mass production of amylase enzyme.

Biofilms are microbial aggregates that adhere to a substrate as a surface and are surrounded by an exopolysaccharide matrix. The bacteria that make up biofilms are so resistant to antimicrobials and antibiotics that this has led to concerns in the medical community.The aim of this study was effect of silver nanoparticles on surface hydrophobicity and biofilm formation in Staphylococcus aureus, Acinetobacter baumannii, Pseudomonas aeruginosa and Escherichia coli. This study was performed on 40 bacterial strains including Pseudomonas aeruginosa, Staphylococcus aureus, Escherichia coli and Acinetobacter baumannii isolated from Milad Hospital in Tehran. The strains were identified by biochemical tests. Also, biofilm formation by microtiter plate method, surface hydrophobicity by MATH method and sensitivity of strains to silver nanoparticles were evaluated. According to the results obtained in this study, all strains were able to form biofilms and no strains with negative biofilms were observed in the study. The highest effect of silver nanoparticles in this study was observed on strains at concentrations of 0.5, 1 and 2 μg / ml. Also, only 20% of Pseudomonas aeruginosa strains in this study were observed with moderate hydrophobicity and the others of the bacteria were weakly hydrophobic. silver nanoparticles in low concentrations with the effect of low toxicity had the ability to inhibit the biofilm formation of Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa and Acinetobacter baumannii. Hydrophobicity in the studied bacteria were weak.

Breast cancer is the most common type of invasive cancer and the second cause of cancer-related death in women. Therefore, evaluating the molecular mechanisms is of crucial importance in this respect. the CCND1 gene encodes the Cyclin D1 protein and Cyclin D1 overexpression has been shown to correlate with early cancer onset and tumor progression. Cyclin D1 overexpression can also down-regulate Fas expression, leading to increased chemotherapeutic resistance and protection from apoptosis. In addition, Integrin beta-1 (ITGB1), is a cell surface receptor that in humans is encoded by the ITGB1 gene. Abnormal levels of integrin beta-1D have been found in limb girdle muscular dystrophy and polyneuropathy.Sample from tissues of 30 patients with breast cancer and the normal margin of tissues were bought from Imam Khomeini hospital. Afterwards, genomic RNA extraction and cDNA synthesis using quantitative real-time PCR method was implemented and after primer design for CCND1 and ITGB1 genes, gene expression was analyzed. The CCND1 and ITGB1 genes demonstrated a significant expression increase in breast cancer tumor samples compared to adjacent normal samples (P <0.0001). The increased expression of CCND1 and ITGB1 genes may enhance the process of cell cycle and this condition can develop tumorigenesis; however more research is needed to confirm these findings.

Millions of tons of plastics are produced annually in the world, which are very durable and take hundreds of years to decompose on their own. Bioplastics are a special type of plastic that is produced from sources of vegetable oils, starches, cellulose or bacterial derivatives and is very different from ordinary plastics in this regard, which will be a good alternative to plastics in the future. 70 samples were collected from waste recycling site, cultured and purified on nutrient agar and these samples were stained with blue indigo staining method to detect polyhydroxy butyrate (PHB) generating isolates And cultured for 2 days at 37 ° C in Minimal Broth Davis medium.After placing the samples on the slide and staining according to the intensity of the color that was created, it was used to produce bioplastics. The results of this study showed that the microorganism Bacillus cereus produces abundant poly-3-hydroxybutyrate in both environments (wastewater and soil), which is used to produce bioplastics on both laboratory and industrial scales. According to the results, the production of bioplastics is possible through bacilli isolated from bacterial isolates.

Turtles are reptiles of Testudines order and they are considered as key species in the habitat, their presence contributes to the survival and sustainability of biodiversity. The aim of this study was to investigate the distribution and species diversity of turtles in the southeast of Tehran province. Turtle sampling was done in from spring to the end of summer 2015 was done monthly and based on field work in 12 stations but turtles were present in only 5 stations, there was a turtle, so that no turtles were found in Pishva and Pakdasht counties.56 turtles were collected from 5 stations in the southeast of the province. After complete biometry and sex determination, they were measured by identification keys. From the 56 collected sample, 36 were male and 20 were female. All species belonged to Mauremys caspica caspica subspecies. After identification, statistical analysis of data was performed using Excel and Spss software. Although numerically the highest number of samples was related to Shahzadeh Mohammad-Ijdan and Bahram Lake stations and the lowest number was observed at Davoodabad village station, but statistically it was found that there is no significant difference in the distribution of this species between stations that the sample was found (p>0.05). The male to female sex ratio was 1: 1. There was also a significant difference between sex and tail length, distance from Plastron to cloaca and distance from cloaca to end of tail (p<0.01).