فصلنامه دنیای میکروب ها
سال سیزدهم شماره 1 (پیاپی 42، بهار 1399)

Microbial biofilms are one of the most important microorganism’s forms of life in the environment. The aim of this study was to use native Pseudomonas aeruginosa in biofilm form to clean up phenanthrene.

Among 63 Pseudomonas isolates from Iranian soil, bacterial isolate with high potency in biofilm formation and crude oil degradation was selected and genetically identified. The effect of inorganic (raw pumice, processed pumice and perlite) and organic (biochar and sugarcanes bagasse) carriers on biofilm formation was investigated. Biofilm structure was studied by scanning electron microscopy. Also, the effects of two growth form (biofilm, planktonic) on biochar carrier on laccase production and phenanthrene degradation in liquid media was investigated.

Purified Pseudomonas isolates were screened based on biofilm formation and crude oil degradation. B59 (Pseudomonas aeruginosa) with 56.62% showed the highest percentage of crude oil degradation. Highest and lowest CFU belonged to biochar and processed pumice with 8.8 and 2.9 respectively. Laccase activity was measured in biofilm form and planktonic form 39.8 and 33.1 Um-1 respectively. Biofilm form of Pseudomonas aeruginosa led to 97.17% phenanthrene degradation where planktonic form reached 91.37%.

Results showed that biofilm form of Pseudomonas aeruginosa compared to planktonic form by significant increase in CFU and laccase activity result in more phenanthrene degradation in liquid media.

Polyhydroxybutyrate is a biopolymer Produced by bacteria. Also, with having chemical and physical characteristics similar with artificial plastics are completely biodegradable and compatible with life-environment. This study has been done with the purpose of separating and knowing one local strain with the ability of high-production for industrial purposes.

In the present analytical research, the sampling from petrochemical wastewater has been done. The existence of polyhydroxybutyrate in separations has been studied with Sudan black staining. One separation of bacillus was chosen to increase the production of polyhydroxybutyrate. This separation was distinguished with biochemical methods and determining 16S rRNA gene sequencing. The final confirmation of Polyhydroxybutyrate synthesis was done through Fourier transform infrared spectroscopy and Proton nuclear magnetic resonance. To increase more production of polyhydroxybutyrate, the effect of different factors including carbone, nitrogen, pH and temperature were assessed.

As a whole, eight bacterial isolation producing polyhydroxybutyrate were separated that among them the one novel strain of bacillus cereus was chosen as better separation. The best conditions to increase more production of polyhydroxybutyrate, was the application and use of glucose as carbon source, ammonium sulphate as nitrogen source, 7 pH and 30°C temperature.

Valuable data on optimized conditions for PHB production has been obtained through the present research that can be used at industrial level for PHB production, so it can be called a quick appearing alternation for petroleum based on synthetic plastic.

Enterohemorrhagic Escherichia coli is one of the major reasons for the bacterial diarrhea. Despite the vast development, there is still no comprehensive treatment for this infection. Vaccine development is the first strategy against bacterial resistance. Due to the pathogenicity of Escherichia coli, the present study was aimed to investigate the role of different adjuvants for vaccination against this bacteria.

The bacteria were cultured and inactivated by formaldehyde for antigen preparation and injection into the mice. Female Balb/c mice were injected subcutaneously with four different bacterial groups including, bacteria with alum adjuvant (AO), montanide adjuvant (MO), non-adjuvant bacteria (O) and control group. Following, the reminder dose was injected after 14 days and blood samples were collected during 7 weeks. The Elisa test was used for evaluation of antibody titer. 28 days after post immunization, the mice were challenged and were evaluated for 72 h. Statistical analysis was accomplished using ANOVA and SPSS software.

The results suggested that while the highest antibody titer was obtained for the AO group, but the MO group has more antibody titer in the first month. Also, challenge results exposed that the AO group protected 100 % of the challenge group mice.

consequently, the produced antibody of the alum adjuvant keep higher the animal’s immune system for a longer period. Since vaccine design to prevent infectious diseases requires effective antigen delivery system, this study could be a new strategy to produce the E. Coli O157:H7 vaccine.

Cytochrome P450 enzymes are a large family of proteins containing haem and play an important role in metabolism of various compounds. Entomopathogenic fungus, Beauveria bassiana also contains these enzymes for targeting insect alkanes. The aim of this study was to investigate the properties and protein structure of seven cytochrome P 450 enzymes in this fungus and to predict the three-dimensional structure of these enzymes by homology modeling method.

Predicting possible situations with intracellular helices was performed with the TMHMM program. SignalP4.1 program was used to predict the probability of the presence and location of shear sites of signal peptides in amino acid sequences. Some of the physical and chemical parameters of the proteins were performed with the ProtParam program. The modeling was conducted in the Modebase database.

In all sequences, a motif was identified and had about 200 amino acids that were related to P450. The motif was in the sequence of 96-45 to about 477-520. CYP539B5 and CYP52G11 proteins were stable. CYP584Q1 had the highest and CYP617N1 had the lowest hydrophilic acid of all. Among the selected models, the model with lowest e-value and the highest coverage was selected as the best model. CYP5337A1 and CYP52G11 lacked helix and CYP617N1 had two helices. Number of estimated amino acids in the helices, in all cases except CYP584Q1, CYP5337A1 and CYP52G11, was greater than 18. No signal peptide was detected.

In this study, the modeled structures of seven cytochrome P450 enzymes were reported for the first time in the fungus B. bassiana. The enzymes' stability and their resistance to adverse environmental factors such as temperature and UV can increase the fungal pathogenicity against the pests.

Pollution of the environment with petroleum and its derivatives is a serious threat to human health and the environment, so treatment of these substances is of great importance. The bioremediation process is defined as the use of microorganisms to remove many industrial effluents, including petroleum products. The aim of this research is isolation and characterization of crude oil degrading bacteria from some industrial sewage at Shiraz province

This study was performed to isolate crude oil degrading bacteria from some industrial areas of Shiraz. To investigate the effect of crude oil on the frequency and variety of microbial populations of Soil and water sampling, identification and counting of crude-oil degrading bacteria and heterotrophic bacteria were performed by CFU and MPN methods. Preliminary identification of the strains was carried out based on gram staining, colony shape and microscopic characteristics. Then properties such as oil-spreading,emulsifying activity and growth and degradation rate of these bacteria were investigated.

After screening, it was found that 20 strains were capable of growing and decomposing crude oil The highest oil-spreading,bacterial adhesion to hydrocarbon, emulsifying activity were related to PE3, SN1, DS1, 23%, 16% and 22%, respectively. Using these results seven suitable strains were selected and crude oil removal rates were determined by spectrophotometric and gravimetric methods for each strain. One strain with the highest rate of crude oil degradation was identified molecularly. This strain belonged to the genus Cellulosimicrobium cellulans. The highest percentage of degradation by this strain was in the concentration of 1.5% at 67%. Percentage of oil degradation of this strain by analyzing the effects of mixture culture, excess carbon source, excess nitrogen source, excess carbon and nitrogen source, time was 75%, 71%, 100%, 81%, 100%, respectively.

The results of this study showed that the use of these microorganisms by creating optimal conditions can be an important step in the removal and control of oil pollution.

Cadmium is one of the most important heavy metals in the soil that is environmentally important in humans and causes numerous health effects for humans. The aim of this study was to evaluate the effect of cyanobacteria  Spirulina platensis (arthrospira platensis) on reduction of cadmium accumulation in liver and kidney of C57 mice.In this study, 16 C57 mice were randomly divided into 4 control and treatment groups. The control group was treated with physiological saline and the groups were treated with 1000 µg / ml cadmium chloride , 1% spirulina in diet and mixture cadmium and spirulina . On day 24, mices were killed after anesthesia with ether and cadmium levels in the feces, liver and kidney were measured by atomic absorption spectrophotometry.Cyanobacteria Spirulina platensis increased concentration of x percent cadmium excretion in the feces and reduce the heavy metal accumulation in mouse kidney C57 Y percent respectively.According to the findings of this study, it can be concluded that the use of this bacterium has a significant effect on decreasing digestive uptake of cadmium.

Finegoldia magna is a potential opportunistic pathogen for humans. F. magna as the most frequent pathogenic species of gram positive anaerobic cocci accounts for up to 5-12% of all anaerobic infections. F. magna possess Protein L super antigen and Type IV Pilin PilA as invaluable proteins for designing multi epitope peptide vaccines in current study.

In this study, immunoinformatics tools were used to predict B and T cell epitopes of Protein L and Type IV Pilin PilA. The epitopes were evaluated for antigenicity, allergenicity and binding energy to appropriate HLA alleles and then were fused together by GPGPG and EAAAK spacers. Vibrio cholera Toxin B Subunit was introduced at N-terminus of the constructed vaccine as adjuvant, and with an eye on further identification and purification, a 6×HisTag was introduced at C-terminus. Codon optimization performed for further expression in Escherichia coli host. The amino acid sequence of the multi epitope peptide vaccine used for 3D structure prediction and refinement. Then structural evaluation via ramachandran plot analysis performed. Physicochemical properties and solubility of the constructed vaccine was also studied.

Results showed the selected epitopes with high antigenicity and no allergenicity. These epitopes manifest high affinity toward recommended HLA alleles. The predicted 3D model of constructed vaccine showed high stability, solubility and half-life for expression in E. coli host.

In this study, Protein L and Type IV Pilin PilA used for in-silico designing an effective vaccine against F. magna. Further in-vitro/vivo studies are recommended.

Actinomycetes are commonly known as exceptionally prolific source of secondary metabolites with diverse biological activities. The aim of this study was to identify some actinomycete isolates from Malaysia marine environment and evaluate for type-I polyketide synthase (PKS-I) and nonribosomal peptide synthetase (NRPS) genes as well as antimicrobial activity.

Selected isolates were identified based on their morphology and molecular properties. PKS-I and NRPS genes were detected using specific primers and the potential of their antimicrobial activity was investigated by disc diffusion method.

The isolates varied morphologically on the basis of colony morphology, spore chain shape, aerial and substrate mycelium formation. Based on 16S rRNA gene sequences analysis, isolates Sdstm3k, Sdtm108 and Sdts4 were highly similar to Streptomyces sp. (95 %), whereas isolates Bvpd17e and SctgJI demonstrated highest similarity to Micrococcus sp. M2-19 (99 %) and Micrococcus leteus (95 %) respectively. While isolate Sdsb2k1a and Sdts46 were unidentified. The detection of PKS-I and NRPS genes revealed that only isolates SctgJI and Sdsb2k1a had both genes. Isolates Streptomyces sp. Sdst3k1 and Streptomyces sp. Sdts4 demonstrated the strongest and broadest spectrum of antimicrobial activity against 10 human pathogens tested.

The present study indicated that actinomycetes isolated from marine environment in Malaysia can be a good source of the discovery of new bioactive compounds.