فصلنامه دنیای میکروب ها
سال سیزدهم شماره 4 (پیاپی 45، زمستان 1399)

Helicobacter pylori is a Gram-negative bacterium that colonizes the gastric tissue of more than half of the world's population and is the major risk factor for the development of gastric cancer.  H. pylori is the most common bacterial pathogen in humans, and there is a significant association  between H. pylori infection and gastric cancer. Autophagy is a protective process used by  eukaryotic cells to maintain cell homeostasis and defend against the attack of pathogenic    microbes. H. pylori can induce autophagy in epithelial cells of the stomach and professional  phagocytes such as macrophages and dendritic cells. Tumor inhibitory proteins including   phosphatases, PTEN, P53, and retinoblastoma protein have a positive effect on autophagy   regulation. In comparison, oncogenic products such as BCL-2 and AKT/TOR pathways play an inhibitory role on autophagy. However, the relationship between regulation of autophagy and   tumorigenesis is still unclear. During H. pylori infection and after the induction of autophagy, the bacterium can escape this process by downregulation of autophagy-related proteins, and/or use the autophagosome as a suitable niche for intracellular survival. In addition, autophagy can cause cell survival or cell death through the gastric cancer process. In conclusion, the role of H. pylori  infection in induction or inhibition of autophagy process, and its impact on gastric carcinogenic related pathways are a matter of controversy, which need further studies to understand the   interactions between the microbe and autophagy.

Spirulina is a photosynthetic cyanophyte that can grow in high intensity sunlight and very alkaline conditions and high temperatures. This algae contains vitamin supplements in the diet. Spirulina will be introduced as a complete food source in the near future. In fact, one of the most important problems in the food industry is the use of synthetic preservatives and synthetic food additives that increase the risk of cancer. Therefore, efforts are being made around the world today toisolate new and safe antioxidants from natural sources. Among these, the natural products (secondary metabolites) of cyanobacteria are an important source of new drug compounds.  Natural products not only have medicinal value themselves, but are also used as building models to create synthetic analogues. The chemical composition of Spirulina includes protein (70-55%), carbohydrates (25-25%), essential fatty acids (18%), vitamins, minerals and pigments such as   carotene, chlorophyll a and phycocyanin. Because there is great potential for exploiting this algae and turning it into a dietary supplement in the production of a variety of food products such as cookies and biscuits, ice cream and cream cheese, and that in a small volume of this algae, it can be used as a golden key in nutrition. In this article, considering the potential potential of  Cyanobacterium Spirulina, the morphological structure, life cycle, nutritional composition,  antiviral activity, anti-cancer, anti-inflammatory, safety, anti-nephrotoxicity properties, increased visual acuity, weight loss and Blood lipids are treated. Obviously, the introduction of valuable properties of cyanobacteria Spirulina can be a suitable substitute for many antimicrobial compounds and synthetic antioxidants that not only pose no risk to the consumer, but can also  improve consumer health. On the other hand, since the present study reviews the latest findings on cyanobacteria Spirulina, it is hoped that this study could pave the way for the introduction of    edible microalgae with healing properties that can be used in the food industry.

The carotenoid-producing yeasts have a widespread distribiution  worldwide. However, isolation of carotenoid-producing yeasts with valuable astaxanthin have been only reported from limited areas and specific habitats. The aim of this study was to apply the multiple polymerase chain reaction method for faster molecular screening of isolates for the yeasts in the exudation sap from birch trees (Betula pendula Roth.) in Alborz Province of Iran with astaxanthin production capacity and toevaluate its efficiency.

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).

Out of 42 pigmented colonies during sampling and isolation in one cross-sectional study, 23 pink to red colonies were evaluated by Multiplex-PCR method. Of these isolates, three were positive and the rest were negative. The results were validated by determining the ribosomal gene sequencing.

The present study demonstrates the specificity of the multiple polymerase chain     reaction method in fast and cost-effective molecular screening of astaxanthin-producing yeast   isolates and the applicability of this method to study other natural habitats of these yeasts.

β -lactamase -producing E. coli is the most important agent causing   urinary tract infections both in community and hospitals. Strain typing including MLVA and PFGE are the most common epidemiologically   tools not only for detecting the cross transmission of nosocomial pathogens but also for determining the source of infection.

The present study was carried of for comparison of discriminatory power of MLVA and PFGE methods. A Total of 230 isolates of E. coli from patients with urinary tract infections were examined for identifying and antimicrobial susceptibility testing MLVA and PFGE methods were used for molecular typing of all isolates.

Out of 230 isolates, 130 ( 56.5%) β -lactamase -producing E. coli isolates were found in this study. The diversity indices of the VNTR loci showed an average diversity of 0.48 and 0.54 for 7-loci and 10-loci respectively. The discriminatory power of PFGE showed a value of 0.87.

Our study showed that PFGE is more discriminatory than MVLA. MLVA is a     PCR- based method and generates unmistakable data, in contrast to PFGE. Optimization of      polymorphic VNTR is essential to improve the discriminatory power of MLVA basis on  geographical region.

Silver nanoparticles (Ag-np) have high penetration and antimicrobial effect due to their high    surface-to-volume ratio. The aim of this study was to biosynthesize silver nanoparticles with red algae extract, Gracilaria gracilis, and to investigate their antibacterial activity against a number of standard and drug-resistant pathogenic bacteria.  First, Ag-np were synthesized. To confirm the structure and size of Ag-np, was used X-Ray diffraction spectroscopy, FE-SEM electron microscopy, and X-ray energy dispersive spectroscopy (EDS). The antimicrobial effects of algae extract on bacteria were determined by sequential dilution method. The size of nanoparticles under electron microscopy was between 12 and 46 nm. The nanoparticles were able to inhibit most of standard and antibiotic resistant bacteria, Ag-np at a concentration of 29 μg /ml, on the standard bacteria: S. typhimorium, E. coli, K. pneumonia and the clinically resistant bacteria, E. coli and           K. pneumonia, they had the most inhibitory effect. In contrast, standard and clinically resistant isolates of S. aureus and    standard strain S. pneumonia were resistant to Ag-np. The results of this research showed that the G. gracilis red algae as a bio-source that can be useful for green synthesis of silver nanoparticles at very low cost applications, these nanoparticles can be used as candidates for drug composition.

The recombinant human IL-11 is the only approved medicine used for treating chemotherapy-induced side effects. Platelet count decreases (thrombocytopenia) in cancer patients who undergo chemotherapy. Interleukin-11 (IL-11) is a platelet increasing cytokine. This study aimed to use two shuttle vectors of pHT43 and pMR12 for cloning the IL-11 gene and     expression of its protein in Bacillus. subtilis and the expression level in these two vectors was   investigated.

In this study, the IL-11 gene was designed and synthesized as a closed structure with two restriction sites for BamH1 and XbaI enzymes and a final length of 609 bp. Then the gene was cloned in two shuttle vectors of pHT43 and pMR12 and transferred to   B. subtilis WB 600. The expression level of the recombinant IL-11 was evaluated with the      Bradford incubation, the pMR12-int11-carrying bacteria expressed higher levels of the protein(75 µg/mL) than pHT43-int11-carrying bacteria.

The results of PCR indicated that the IL-11 gene existed in shuttle vectors pHT43 and pMR12. The expression of this protein was about 75 /g / mL using pMR12 vector, which is higher than the bacterium carrying pHT43-int11.

The expression level of the recombinant IL-11 protein with pMR12 vector was higher than pHT43 vector. This amount has not been reported so far for IL-11. B. subtilis can express and produce IL-11 and can be used as a source for drug production