فصلنامه دنیای میکروب ها
سال چهاردهم شماره 1 (پیاپی 46، بهار 1400)

TcpA protein and B subunit of cholera toxin are the most important virulence factors of Vibrio cholorea. In the current survey, we applied the C-terminal of   clostridium perferingenes toxin as a delivery system to bind the CtxB-TcpA fusion as an antigen,      cloning it in a prokaryote vector, evaluated the level of  expression.

In experimental survey, the ability of a constructs based on  CtxB-TcpA-C-CPE with complete protein sequences of each protein was studied. After amplification of tcpA, ctxB, and c-cpe genes using PCR, they were cloned in expression plasmids. For fusion protein, all of the three protein sequences were constructed with linker. After  expression, the proteins were purified and then confirmed using immunoblot methods.  

This fusion protein consists of 484 amino acids. PCR amplification for the c-cpe, tcpA and ctxB genes amplified 381, 375 and 675 bp; respectively. The result of enzymatic restrictions and sequencing indicated the exact homology of the synthesized proteins and the others submitted in NCBI. According to the SDS-PAGE results, the TcpA, CtxB, and C-CPE proteins were 15, 25 and 25 kD respectively.

According to physicochemical results, this fusion protein may be suitable candidate as a vaccine, however; further experimental trials are needed to approve this conclusion.

Despite of widely use of pesticides in agricultural industry, their ecotoxicological impacts on the ecosystems has not been well understood. In the present study, the effects of chlorpyrifos and deltamethrin as a representative of organophosphorus on soil microbial diversity in different salinities were investigated.

soil samples with different salinities (0, 1%, 2% and 4%) were contaminated with 200 mg/kg of chlorpyrifos and deltamethrin. Then, the effects of these compounds were investigated by microbial cultivation and Next Generation Sequencing (NGS) methods. The dominant bacterial strains were isolated and compared with the results of the NGS method.

Remarkable groups of active soil species were destroyed. The main groups at the phylum level were, Firmicutes, Proteobacteria, bacteriodes and actinobacteria. Examination of the pattern of operational taxonomic unit (OTU) showed that the lowest abundance belonged to the group of soil samples contaminated with chlorpyrifos and the highest abundance belonged to the non-contaminated sample. Alpha diversity analysis revealed that the highest number of strains was observed in non-saline and uncontaminated soil microcosms, and the lowest number of strains was observed in the presence of deltamethrin (1% salinity) and chlorpyrifos (0% salinity).

The results indicated that soil salinity had significant impact on the resistance of soil microorganisms to the chlorpyrifos and deltamethrin. Every soil samples will have its own microbial composition based on its physicochemical conditions under the influence of pesticide contamination. By comparison of microbial composition by culture-dependent and molecular-based methods, almost similar findings were obtained.

The use of nanoparticles is one of the newest methods of making vaccines. Nano-vaccines based on biodegradable polymers produce stronger immune system responses. The aim of this study was to design a Haemophilus influenzae type b nanovaccine in an animal model.

In this study, PRP of Haemophilus influenzae was loaded in the structure of PLGA-Chitosan nanoparticles. Confirmation of AFM, FT-IR size and charge, percentage of release and loading of antigens from the structure of nanoparticles were calculated and the toxicity and antigenicity of nanovaccines were tested by ELISA method. Four groups of female mice were selected and grouped for vaccination. Vaccination and blood sampling were performed from mice’s heart and serum samples were collected and antibody responses against PRP were measured for total IgG and IgM. Pathological examination was performed to evaluate the extent of tissue damage.

Increasing the particle size from 167 ± 47.3 to 209 ± 4.2 and AFM electron microscope images before and after antigen loading showed the success of antigen encapsulation in the nanoparticle structure with 78% efficiency. The results of ELISA and vital organ pathology showed an increase in the titer of total IgG and IgM antibodies in the HIB nanovaccine compared to PRP and the lack of toxicity of the nanovaccine in the vital organs of mice.

The results indicate that resulting nanovaccine has far more absorption and immunogenicity and can act as an effective vaccine against Haemophilus influenzae type b diseases.

Type 6 secretory system (T6SS) and the presence of a strong efflux pump due to membrane purine are important indicators of pathogenicity of Acinetobacter baumannii. This study aimed to track the secretory system of T6SS and membrane purine as well as the pattern of antibiotic resistance in clinical isolates.

This cross-sectional descriptive study was performed on 33 strains of A. baumannii isolated from clinical samples including blood, urine, respiratory trachea, and wound. Antibiotic susceptibility of isolates was evaluated by the disk diffusion method according to CLSI protocol. Also, the frequency of genes encoding the effector proteins secreted from the type 6 secretory system and membrane purine was determined using Multiplex PCR.

31 strains of A. baumannii were identified, using the molecular method. A. baumannii isolates showed 93.55% sensitivity to colistin sulfate. The lowest susceptibility was related to five classes of antibiotics: fluoroquinolones (12.9%), cephalosporins (6.45%), aminoglycosides (6.45%), macrolides (16.1%), and inhibitory antibiotics (12.1%). The results showed that in addition to the MDR phenotype (100% of isolates), 20 isolates (64.52%) had the XDR phenotype. The frequency of the hcp gene was confirmed in 18 isolates (58%) and ompC in all isolates (100%). Also, the frequency of the ompC gene in MDR and XDR isolates was 100%. However, the hcp gene was observed only in the XDR phenotype with 90% frequency.

The results of this study showed the possible effect of the hcp gene on the compatibility of A. baumannii isolates with unfavorable conditions and the occurrence of resistance phenotype.

Pollution of the environment with metals is a serious treatment to    human health and the environments. The purpose of this study of arsenic biosorption was from     several industrial effluents.

This cross-sectional study was carried out by sampling in May 2018 from one of the natural habitats of birch trees Batula Pendula in Alborz Province, Iran. After isolation of yeasts using selected media and purification of yeast colonies with various pink to red colors, yeasts genomic nucleic acids were extracted and molecular screening for astaxanthin-producing detection of isolates was performed by multiple polymerase chain reaction (Multiplex-PCR).

The concentrations of arsenic in effluents (1) and (2) were 0.730 and 1.895 mg/L, respectively and the pH of both effluents was neutral. The effluent BOD and COD effluent (2)was within the standard range, but the BOD and COD effluent (1) was somewhat higher. The number of heterotrophic bacteria in effluent (1) was higher than effluent (2), but there was no significant difference between these two effluents . Arsenic-resistant isolates in both effluents were Bacillus syphenis OPL, Pseudomonas aeruginosa IAUF-11ZBK, Stenotrophomonas maltophilia IR-Isfahan (G) and 5633. Pseudomonas aeruginosa ZBK showed the highest sensitivity to antibiotics, which was able to biosorption  of arsenic from  municipal wastewater up to 1.4 mg/L in vitro.

Pseudomonas aeruginosa  ZBK had a good ability to biosorption  of arsenic and low resistance to antibiotics. This strain is recommended for biosorption of arsenic from effluents.

Climate change is one of the most important issues that has attracted a great deal of attention and caused many environmental problems for health systems and global economy. Studies have shown that during climate change, microorganisms can change and cause many problems including the recurrence and spread of infectious diseases, emerging diseases (COVID-19 pandemic), and antibiotic resistance. Besides, it will lead to famine, drought, floods, and global warming that threatens the lives of many people. Reducing greenhouse gas emissions, especially the use of less fossil fuels in industry, can be a preventative way. Therefore, it is significant to have plans to deal with climate change consequences in the environment. In this article, 71 articles from 1992 to 2020 were reviewed by mentioned keywords. Some specific extreme environments that are rich in valuable secondary metabolites and microorganisms but are fragile to climate change and also their microorganism’s diversity and population which have been changed during climate change were reviewed.