فصلنامه دنیای میکروب ها
سال چهاردهم شماره 2 (پیاپی 47، تابستان 1400)

Background &

Laccases are enzymes that belong to the group of oxidases that have different applications in various industries. The aim of this study was to evaluate the activity and stability of the laccase enzyme produced by a native Aspergillus spp. isolated from olive oil waste. High inducer phenolic compounds content of these wastes is main reason of their selection as substrate. Materials &

In this study, 12 different fungal strains were isolated from olive oil wastes and the best strains with the highest enzyme activity was selected as the best strain and was     identified based on phenotypic and genotypic characterization. Enzyme purification was           performed using dialysis and zymographic analysis methods. Finally, the effect of various       physic-chemical factors such as incubation time (6-216 h), temperature (20-40 C) and pH (5, 6, 7 and 8) on the enzyme stability and activity was evaluated.

The results showed that the best productive strain belongs to the genus Aspergillus spp. The highest enzyme activity was observed at 30 °C (1.57 IU/ml), pH = 6 (1.86 IU/ml) and after 6 days (1.53 IU/ml). Stability studies showed that the enzyme activity was stable for 6 minutes at  30-35 °C and pH = 6-7 and about 90% of the enzyme activity was maintained under the above conditions.

The laccase enzyme with significant activity and stability produced by a native strain of Aspergillus spp. isolated from olive oil waste due to its high activity and stability can be an  acceptable candidate for industrial use.

Background & Calcite precipitation by microbial stimulation (MICP) is the new method which used for soil stabilization and solidity. Biocementation is an ecological process based on microbial urease enzyme activity. The present study aimed to isolation and identification of Bacillus spp. with MICP potential from various ecosystems of Iran.Materials & This cross-sectional study was conducted on 200 soil samples collected from arid and desert ecosystems of Iran. Bacillus were isolated and characterized by conventional microbiology tests and molecular methods include the amplification and sequences analysis of gyrA and 16S rRNA genes. Growth in presence of urea, different salinity, pH and temperature, also SEM, XRD and wind tunnel analysis were used to determine biocementation ability. A total of 5 Bacillus isolate with strong urease activity belonging to 4 different species include B. amyloliquefaciens, B. thuringiensis, B. carboniphilus and B. oleos were identified. Optimum conditions for MICP by isolates are 35°C, pH 8.8 and 6% salinity. Moreover, the results of wind tunnel after MICP showed a 100-fold reduction in soil loss at a flow rate of 100 km/h. The results showed that indigenous Bacillus spp. have a significant potential to produce bio-cement. Therefore, its suggest the MICP process have been used to reduce soil losses due to wind erosion, stabilization of loose sands and ground consolidation in the desert soils of the country.

Cumin )C uminum cyminum L.) is an annual plant belonging to Apiaceae family. One of the major diseases of cumin is Fusarium wilt caused by a soil-borne, vascular wilt pathogen Fusarium oxysporum f.sp. cumini which is a devastating disease that occurs in major cumin growing areas of the world; while plants reach to 0.5- 2.5 cm in height, they die as the result of the disease. In the current research, 80 isolates of Streptomyces spp. isolated from the rhizosphere soil of Astragalus sp. and screened against Fusarium under laboratory condition. Three out of 80 isolates including M15, M26 and M80 revealed having the highest antagonistic activity, hence, selected for further evaluation under greenhouse conditions. After emergence of cumin seedlings, mortality and growth indices were compared between different treatments weekly and results were recorded. Plants were harvested after teen weeks and growth indices such as plant height and weight were recorded. The Streptomyces sp. Isolate No. M15 was showed the strongest effects on plant growth and suppression of the wilt disease as compared to the controls. The present research is an attempt to control cumin Fusarium wilt disease using Streptomyces spp. The final goal of this research is to introduce an effective biological agent for controlling managing Fusarium wilt disease under field condition. this pathogen.

Background & Chlamydia spp. is an obligate intracellular agent that causes           chlamydiosis in animals and humans. Chlamydia infections in cows can cause abortion, infertility and other symptoms. The aim of this survey was to investigate the frequency of chlamydia        infection in sperm used by artificial insemination.Materials & In This survey semen samples were collected from semen supply centers. Then DNA was extracted using Cinnagen company kit. The samples were Analysed for the     chlamydial agent by Nested polymerase chain reaction (Nested PCR) by 16SrRNA gene primer and then the PCR product was electrophoresed and positive samples were identified by genus and species. The finding of this survey indicated the prevalence of infection of different chlamydial species in the sperm samples. A Total of 100 samples were tested, 23 samples were positive for chlamydia spp.which are 12 positive samples separately for Chlamydia Pecorum,Chlamydia   abortus 7 positive samples and 4 positive samples were identified for Chlamydia Psitassi. The present survey showed that sperm samples can be an important source of      chlamydial infection transmission in bulls.

Proteus is one of the most important causes of UTI and nosocomial infections. Nowadays, the focus is on the antibacterial effects of natural products. The aim of this study was to investigate the effect of myristic acid and iron nanoparticles on the expression of Proteus Mirabilis pathogenic genes isolated from urine samples. In this cross-sectional study, urine samples were collected from outpatients and patients admitted to hospitals and clinics during six months. After identification of Proteus mirabilis using standard methods, these isolates were tested for antibiotic resistance. After identification of the target gene bacteria, iron nanoparticles and myristic acid were treated and the expression of flaA and ureA genes in these bacteria were evaluated. Finally, 6219 positive urine samples were collected from which 3937 (63.3%) were female and 2282 (36.7%) were male (mean age 16 69 69 years). Sixty Proteus mirabilis strains were isolated. Out of 60 clinical samples, flaA gene was present in 100% and UreA gene in 91.65% of isolated bacteria. The results showed that the expression level of flaA gene in isolates treated with mixture of myristic acid and iron nanoparticles decreased by one quarter of normal in isolates (p = 0.002). The data showed that iron oxide and meristic acid nanoparticles have strong antibacterial activity against Proteus mirabilis strains with flaA gene. In addition, these compounds decreased flagellin gene expression, which may indicate regulatory systems responsive to external signals. Therefore, these two substances can be considered as grounds for further studies on infection control.

Background & Tomato yellow leaf curl disease (TYLCD) is one of the most common and important tomato diseases in Iran. Sequences of viral genomes help to find and interbreed    resistant plant varieties. This study aimed to sequence the complete genome of an isolate of the TYLCV, determine its strain and taxonomic status.Materials & For this purpose, a viral isolate from Assaluyeh was selected and studied. Using degenerate primers of begomoviruses (BC/PCRV 181) a fragment (500bp) of the genome was amplified in a polymerase chain reaction (PCR). According to the sequence of this fragment (500bp), a primer pair was designed (FarsC/FarsV) to achieve the full genome sequence of the virus. By utilizing a combination of primers (FarsC/PAL1V 1978) / (FarsV/TYLCV-[Ab] 1997C) complete sequence of Asalooyeh isolate was amplified and the taxonomic position of that isolate was determined. Phylogenetic analysis showed that this isolate had a one-part genome and was more than 93% similar to the Omani strain. Therefore, this isolate is an Omani variant of the virus. In other researches, was stated that there is only TYLCV-IL strain in Bushehr province, while the results of this study prove the existence of TYLCV-OMN strain. According to the results of this study Asalooyeh isolate of TYLCV belongs to the Omani strain of TYLCV that produces severe yellowing in host plants.