فصلنامه زیست شناسی میکروارگانیسم ها
پیاپی 43 (پاییز 1401)

All plants in natural ecosystems seem to symbiose with fungal endophytes. This highly diverse group of fungi can have profound effects on plant communities by helping to tolerate abiotic and biological stresses, increasing biomass, and reducing water consumption or changing resource allocation.

In this study, the spatio-temporal biodiversity of fungal endophytes of Fusarium sp. and Thielavia sp. isolated from six species of halophyte plants was examined. The spatio-temporal biodiversity of these two fungal endophytes in different tissues of halophyte plant species was assessed by PAST software using Simpson, Shannon, and Margalf richness indices. The ITS-specific primer was used for the molecular identification of fungi.

The results of the study showed that the highest frequency was related to the fungal endophyte Thielavia sp. 21.75% in the stem. Examination of the Simpson, Shannon, and Margalf richness indices showed that the highest fungal endophyte diversity for these indices were 0.498, 0.691, and 0.445 in the stem of Bienertia cycloptera, respectively. Also, the results of the Simpson and Shannon diversity index showed that the highest fungal endophyte diversity of 0.500 and 0.693 was observed in the plant species of Abu Musa Island, and for the Margalf richness index, the highest fungal endophytic diversity of 0.455 was observed in Sirik port.

The results of this study showed the high spatio-temporal diversity of the two fungal endophyte species in the six saline plant species studied. Based on this information, it can be concluded that the supply of endophytes from geographical areas in which plant species are highly diverse, can be effective in the success of the plant colonization program.

Tolerance to ethanol is a key characteristic of the yeast Saccharomyces cerevisiae. Any increase in ethanol tolerance in the industrial strains could lead to faster and more complete fermentations, and may also allow the production of more alcohol. Due to the complex nature of ethanol tolerance, it appears that a large increase in ethanol tolerance requires several changes in the yeast’s genome. Several approaches that rely on the effect of (random) variation generated by evolutionary engineering or mutagenesis have successfully yielded strains with increased ethanol tolerance.

In the present study, to improve the ethanol tolerance phenotype in the industrial Ethanol Red strain, the parent strain was mutated physically and chemically. The mutants were screened using 1-butanol containing medium. The primary parent and the mutants were evolved within 144 days with evolutionary engineering strategy, while ethanol production of the selected strains was investigated

According to the increase in the maximum growth rate, 8 strains were selected including parental strain and mutants, and the amounts of ethanol production of these strains were evaluated after evolutionary adaptation tests. Ethanol production of ER 103 and ER 106 which were mutated with EMS before the adaptive evolution test and then evolved at 11 and 9% v/v ethanol was improved from 103.44 ± 0.5 g/L to 112.45 ± 1 and 112.3 ± 0.9 g/L, respectively.

Due to the extensive capabilities of the evolutionary engineering method in creating capable strains in order to increase ethanol tolerance in industrial strains, the evolutionary engineering strategy was used. To increase the genetic diversity of the primary population, before starting the adaptive evolution experiments, mutation with ethyl methane sulfonate was used, which was more efficient than ultraviolet radiation in accelerating the evolution process to achieve the desired phenotype.

Cervical cancer is the leading cause of morbidity and cancer mortality in women throughout the world and persistent infection with human papillomavirus (HPV) is the main etiology for the development of this cancer. Peptide vaccines derived from E6 and E7 oncogenes are promising candidates for HPV vaccine production due to their safety, high stability, and ease of production. In the current study, expression strains such as Escherichia coli BL21 (DE3), BL21 (DE3)-AI, Rosetta, C41 (DE3), and BL21 (DE3)-pLysS were applied for poly epitopic E6 expression and the effects of temperature, induction time, and inducer concentration on the expression level of recombinant HPV16-E6 polypeptide protein were examined in the mentioned strains.

In the present study, the optimized gene of E6 recombinant protein was cloned into pET28a vector under the control of T7 promoter and the resulting plasmid was successfully transformed into Escherichia coli strains BL21 (DE3), BL21 (DE3)-AI, Rosetta, C41 (DE3), and BL21 (DE3)-pLysS. Then, the ability of these strains to express the desired recombinant protein in different conditions was compared.  Two temperatures of 25 ° C and 37 ° C, IPTG concentrations between 0.1 and 1.0 mM, and different incubation times were selected to examine the expression level of recombinant E6 protein in these strains.

The highest level of expression was obtained in Escherichia coli BL21 (DE3) -AI strain inducing at Optical Density (OD) of 0.9, 0.1 mM IPTG, and 16 hours induction at 25 °C.

The results of this study can be used to produce E6 protein as a vaccine candidate in the treatment of HPV-related cancers.

Electronic wastes are the remnants of electronic devices buried in the soil without processing and contain toxic substances such as heavy metals. Lead is one of the heavy metals in many electronic goods that, if not properly processed, can cause toxicity in the soil and may harm living things in very low concentrations. Therefore, the aim of the present study was to investigate the biosorption of lead metal by Bacillus tropicus isolated from soils containing electronic wastes in Isfahan.

In this cross-sectional study, sampling of contaminated soils in several areas of the Zainal Pass hills of Isfahan, which is the landfill of electronic wastes, was performed. After measuring the temperature, pH, TOC, and the amount of metals in the soil sample, lead-resistant bacteria were isolated. The growth rate of bacteria was evaluated at concentrations of 5 to 35 mM of lead. Then, the minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) were determined. The morphology, antibiogram, and molecular identification of the bacteria were performed by colony-polymerase chain reaction method and bioabsorption of bacteria was evaluated by ICP-OES. Finally, XRD, SEM images, and EDS were evaluated to investigate the fabrication of lead nanoparticles. The raw data were analyzed by SPSS software, using an independent t-test.

Based on the findings of this study, the pH of the evaluated soil was 9.4, its temperature was 27.8 ° C, the TOC of the sample was 1.8%, and the amount of soil lead was measured at 658.4 ppm based on ICP-OES analysis. It was significantly higher than normal. The lead-resistant bacterial strain isolated to lead had 99/69% genetic affinity with Bacillus tropicus, which had a high biological removal potential (56.35%) of lead metal.  The XRD, SEM, and EDS results showed the conversion of adsorbed lead metal to nanoparticles.

Considering that Bacillus tropicus showed high resistance and adsorption to lead metal, it can be a suitable option for the bio-removal of lead from electronic and other industrial wastes in the future after the removal of antibiotic resistance genes.

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.

Hydrogen gas has great potential as a renewable energy source. Although hydrogen gas is obtained from fossil fuels, there is a demand for its production by chemical methods and electrolysis of water, and its extraction from oil sands is currently being studied. Its biological production is one of the cleanest types of hydrogen fuel production due to the consumption of greenhouse gases such as carbon dioxide and/or aerobic and anaerobic fermentation of agricultural wastes, and it can be considered as a solution for simultaneous production of the fuel and elimination of environmental pollutions.

The present study briefly explains the hydrogen-producing microorganisms, the mechanisms, and the effective enzymes in their production. For this purpose, authoritative articles published between 2006 and 2021 and information in the Scopus database have been used to draw graphs and write this review article. In addition, some limitations and the ways to overcome them for increasing biohydrogen production are described in detail.

The results show that carbon dioxide fixation, fermentation, nitrogen fixation, aerobic and anaerobic photosynthesis are some ways of biological production of this fuel.

Important elements in biological production are the effective enzymes in these reactions and the possibility of using these enzymes in the continuous production of gas, and the purification of hydrogen from other gases. The stabilization of these enzymes under their conditions is of particular importance for the mass production of this gas. Purification of bio-produced hydrogen gas is essential for consumption as fuel, and some technologies, including nanomembranes such as polysulfonate, are very helpful in purifying this gas from other gases such as oxygen, nitrogen, ammonium, hydrogen sulfide, and oxygen.