فصلنامه زیست شناسی میکروارگانیسم ها
پیاپی 41 (بهار 1401)

Tyrosol (2-(4-Hydroxyphenyl) ethanol) is one of the natural phenolic compounds in olive which has antioxidant and anticancer effects. During the olive oil mill process, a lot of the phenolic compounds are released into the water which can contaminate the environment.However, these can be converted into useful ingredients and valuable dietary supplements. In the present study, tyrosol was converted to hydroxytyrosol by spore displayed tyrosinase and the anticancer effect of hydroxyl tyrosol was studied on MCF-7 breast cancer cells.

Spore suspension of the recombinant Bacillus subtilis DB104 (pSDJH-cotE-tyr), constructed in our previous research by genetic engineering methods and surface display technique, was prepared in sporulation medium. The spores were used in the bioconversion of tyrosol to hydroxytyrosol and the reaction was assayed by high-performance liquid chromatography. The anticancer effect of hydroxytyrosol on the MCF-7 breast cancer cell line was studied by a flow-cytometer.

The results of the study revealed that 1mM of tyrosol was converted to 1mM of hydroxytyrosol after 60 min. The anticancer effect of hydroxytyrosol on MCF-7 was determined more than 80% after 48 h incubation.

According to the obtained results, spore displayed tyrosinase as an active enzyme is able to produce useful compounds with anti-cancer properties from olive oil derivatives. The anti-cancer effects of hydroxytyrosol produced by biotransformation of tyrosol on MCF-7 breast cancer cells are confirmed by previous studies.

Clavulanic acid is the first B-Lactamase inhibitor that has been used clinically since 1981. This inhibitor is the natural product of the fermentation of Streptomyces clavuligerus and is useful for protecting B-lactams against lots of important B-lactamases such as Group A B-lactamases and Group D Cloxacillin lysis enzymes. The aim of this study was to optimize the composition of the fermentation medium in terms of the carbon source in the production of clavulanic acid.

In this experiment, the influence of different concentrations of glycerol 15 g/L, wheat bran 17 g/L, and glucose 18.1 g/L on the production of clavulanic acid was tested. After passing the levels of sporulation, seeding, and fermentation, the influence of different concentrations of glucose, wheat bran, and glycerol on pH rates, biomass, and morphology of Streptomyces clavuligerus was tested by the light microscope. The concentration of clavulanic acid produced was measured by spectrophotometry.

According to the results, the highest production of clavulanic acid in all substrates was on the eighth day. The use of glycerol at a concentration of 15 g/l produced 238.3 mg/l clavulanic acid, which had the highest production rate and also reduced production costs.

Due to the price, availability, and also increasing the production of glycerol and wheat bran (compared to corn oil), the production of clavulanic acid in environments containing glycerol and wheat bran is easier and more convenient.

Due to the increasing trend of industrial development and also the industrial production, the presence of heavy metals along with industrial wastewater is undeniable. Despite the various ways to remove heavy metals, choosing biological methods can be the best way to control them. Using bacteria in this field can be very useful and inexpensive with less harm.

In the present study, various aquatic environments including rivers, ponds, industrial effluents, and activated sludge were sampled. Bacteria were identified based on the growth in iron-specific culture medium in terms of shape and 16S rRNA gene. These bacteria were cultured in specific culture media for iron-oxidizing bacteria, Luria-Bertoni (LB) and PHG II, containing 2 ppm of mercury chloride and cadmium chloride. The samples were then examined for the reduction or non-change of mercury and cadmium concentrations by atomic absorption spectrometry.

The results of the present study showed that the isolated bacteria were rod-shaped and chemoorganotrophic belonging to the genus Bacillus. The average percentages of mercury and cadmium removal by the isolated bacteria were about 95% and 40%, respectively.  The highest percentage of the removal of both heavy metals was observed in the effluent sample of iron factory wastewater.

Iron oxidizing bacteria were identified as reducing agents of heavy metals in the laboratory environment. These bacteria grew in both LB medium and iron-specific culture medium. The highest percentage of the removal of both heavy metals was observed in the effluent sample of the iron processing plant. Based on the results, it can be said that the bacteria of each environment have adapted to the compounds of that place and are the best option to remove compounds such as heavy metals.

Tyrosine oxidizing enzymes or tyrosinases have various applications in medicine, nutritional, and environmental disciplines. By considering actinobacteria’s impacts as one of the most promising bacteria in producing bioactive compounds and valuable enzymes with medical, industrial, and environmental applications, the current study was performed to screen and identify tyrosinase-producing isolates soil samples of the Maranjab Desert, the Hampoeil cave, and the Hormoz Island.

In this research, the soil samples collected from the Maranjab Desert (10 samples) and Hormuz Island (10 samples) were cultured in ISP2 agar, and the actinobacterial colonies were isolated. The isolates and the previously-isolated strains from the Hampoeil cave were qualitatively screened by culturing on tyrosine agar medium. The result of primary screening was confirmed by culturing in tyrosine broth. Then, the tyrosinase activity of the selected isolates was quantitatively evaluated. Finally, these isolates were identified by sequencing and analyzing the 16S rRNA gene.

Among the 89 screened actinobacteria, 17 colonies showed clear zone and brown-black pigmentation around their colonies on tyrosine agar and were subjected to secondary qualitative screening. The results of secondary screening confirmed that 11 isolates produced tyrosinase. Also, the quantitative test results revealed that the strains designated UTMC 3165 and UTMC 3233 had the most enzyme activity, as 33 and 35 unit/ml, respectively. In the molecular identification, the isolates showed 99.67% and 99.88% similarity to Streptomyces tendae and Streptomyces thermocarboxydus, respectively. 

The results of the present study showed that the soils in Iran possess promising actinobacteria with the ability to produce tyrosinase enzymes. These strains were the members of the Streptomyces genus.

Some tissues of the body such as the amniotic membrane and cheap and available medicinal plants such as Arnebia euchroma can be effective in treating burn wounds, reducing its infection, and healing time. The aim of the present study was to investigate the antimicrobial effects of a combination of amniotic membrane, Arnebia Euchroma (AE) extract, sesame oil, and bee wax on the growth of gram-positive and gram-negative bacteria in second-degree burn wounds. After receiving amniotic membrane tissue from pregnant women, this tissue was mixed with sesame oil, bee wax, and Arnebia Euchroma extract and applied to the burn wounds of mice model infected with E. coli, Staphylococcus aureus, Pseudomonas aeruginosa, and Acinetobacter baumannii. This combination was applied in case and control groups, and microbial counting was then performed. According to the findings of the present study, the number of pathogens in wound samples of mice treated with this combination was less than in control mice. The results of this study also showed that the use of a combination of amniotic membrane, AE plant extract, sesame oil, and bee wax had a therapeutic effect on second-degree burn wounds. The use of this compound after further research is recommended for the treatment of burn wounds.

Copper nanoparticles (CuNPs) are used in various industries, including pharmaceutical and biomedical sciences, agricultural and food chemistry, electronics and environmental applications, due to their novel optical, chemical, photoelectrochemical, and electronic properties as well as antimicrobial activities. The aim of the present study was to evaluate the ability of endophytic bacteria to synthesize CuNPs.

Eighteen endophytic bacteria (CN1-CN18) were isolated from the root and crown rot of the bean. The agar dilution method was used to determe the intrinsic tolerance of endophytic bacterial isolates to copper ions. Characterization of CuNPs was performed using different methods including ultraviolet–visible spectroscopy (UV–Vis), field emission scanning electron microscope (FE-SEM), Fourier transform infrared (FTIR), X-ray energy diffraction spectroscopy (EDS), and powder X-ray diffraction (XRD). The antimicrobial activity of the copper nanoparticles was investigated by the agar well diffusion method.

The results of the study indicated that isolate CN10 was able to reduce CuCl2 to CuNPs. Based on the obtained phenotypic data and 16s rDNA sequence analysis (similarity above 99%), the isolate was identified as Pseudomonas grimontii. Additionally, spherical CuNPs with an average size of 24.8 nm were synthesized by resting cells of strain CN10 under 3 mM of copper chloride, pH 7.0, agitation 100 rpm, and 96 hours of incubation. The results of antimicrobial tests showed that the produced CuNPs exhibited the highest inhibitory effects on Xanthomonas campestris (19.2 mm) and the lowest inhibitory effects on Staphylococcus aureus (9.4 mm).

The current study is the first report on the synthesis of CuNPs using a resting cell of Pseudomonas grimontii. The results suggested the synthesis of CuNPs using endophytic bacteria as a promising tool for the production of CuNPs in a controlled shape and size.