جستجوی مقالات مرتبط با کلیدواژه « bacillus » در نشریات گروه « زیست شناسی »

With the increase of antibiotic resistance, the effort to reduce the consumption of antibiotics by replacing natural active compounds has received much attention in recent years. Cyanobacteria are highly diverse and contain metabolites with medicinal, nutritional and antimicrobial properties.

I In this study, the effect of Spirulina platensis extract on two Gram-positive bacteria Staphylococcus aureus subsp.marcescens and Bacillus subtilis subsp.subtilis (bscillus natto), two Gram-negative bacteria Escherichia coli and Klebsiella pneumoniae and two fungi Penicillium and Aspergillus niger. was investigated. Spirulina platensis hydroalcoholic extract was prepared by maceration method and its antimicrobial activity was evaluated by disk and agar well diffusion methods.

The results showed that the growth of Gram-positive Bacillus was inhibited by Spirulina extract and Staphylococcus aureus showed no sensitivity to the existing Spirulina. Generally, gram positive bacteria were more sensitive than gram negative bacteria. Also, Aspergillus niger showed more antifungal activity than Penicillium. The supernatant showed better results than the hydroalcoholic extract, and diameter the inhibition zone was from 1 to 15 mm.

In general, due to the increasing resistance of pathogenic fungi to common antifungals, it is recommended that with more research on Spirulina microalgae, the antimicrobial compounds of this algae can be used in the treatment of infectious and fungal diseases.

The escalating consumption of chemical fertilizers has imposed severe environmental and economic burdens on the society. Studies have shown the detrimental effects of these chemical agents on human health, necessitating a shift towards alternative fertilization practices. Research has focused on harnessing the potential of naturally occurring soil microorganisms as a sustainable and environmentally friendly solution to enhance plant growth. Biofertilizers, soil amendments enriched with beneficial microorganisms such as fungi, protozoa, actinomycetes, or algae, collectively known as plant growth-promoting bacteria (PGPB), represent a promising alternative to chemical fertilizers. Studies have shown that Bacillus-based biofertilizers can enhance nutrient uptake and regulate phytohormone metabolism within plants. Moreover, Bacillus strains exhibit remarkable resilience under environmental stress and secrete enzymes that disrupt the cell walls of pathogenic bacteria, viruses, fungi, and nematodes, thereby protecting plants from disease and promoting healthy growth and yield. In light of the aforementioned benefits, this study aims to isolate and molecularly identify native Bacillus strains with plant growth-promoting properties. The potential of these strains for incorporation into biofertilizers derived from Iranian native strains will be investigated.

In this study, rhizospheric and rhizoplane Bacillus strains from Iranian agricultural soils with Nitrogen-fixing ability were isolated and characterized for their plant growth-promoting properties. Strains with higher growth capacity were screened by 5% overnight culture in 100 ml NFB medium completed with 0.5% yeast extract. The strains were streaked onto Pikovskaya agar containing insoluble tricalcium phosphate. Quantitative analysis of phosphate solubilization was performed by culturing the strains in the mentioned liquid medium.  For the screening of (IAA) producer strains, the overnight culture of bacteria inoculated to a 250 ml Erlenmeyer-containing nutrient broth fortified with L-tryptophan. Then 2 ml of the supernatant was mixed with 2 ml Salkowski reagent. The optical absorbance was measured at 535 nm and the produced IAA was measured by standard curve graph. Production of ammonia was assayed by inoculation e of strains into peptone water. Nessler’s reagent was added to the medium. The development of yellow color showed the production of ammonia by the strain. The ability of HCN production was assayed by overnight culture of strain inoculated in nutrient agar slant fortified with glycine. The color change of the paper filter soaked in 0.5% picric acid and 2% sodium carbonate from yellow to brown indicated the production of HCN. Evaluation of antifungal activity against aspergillus niger, verticillium dahlia, and fusarium graminearum was performed on potato agar (MPA) plates, and calculated according to the following formula I= [(C-T)/C]*100. Quantitative measurement of ACC-deaminase activity of bacillus isolates was carried out using a modified NFB-ACC medium. siderophore production from cultural variables analyzed by CAS agar plate in reference to the change of color of CAS medium when microorganisms were grown in CAS agar plates. Phylogenetic relationships among the strains were established using 16S rDNA gene sequencing.  GraphPad Prism 6 software was used for statistical analysis. Data analysis was performed using one-way ANOVA and t-test and statistically significant was considered as p<0.05.

In the intricate realm of soil microbiology, the rhizosphere and rhizoplane stand out as vibrant microbial hotspots, teeming with life and playing pivotal roles in plant health and nutrition. The rhizosphere, the narrow zone of soil surrounding plant roots, is a dynamic environment enriched in root exudates, serving as a nutrient-rich haven for a diverse array of microorganisms. Within this intricate ecosystem, nitrogen-fixing bacteria emerge as crucial players, converting atmospheric nitrogen into a form usable by plants, thereby supporting their growth and productivity. Nitrogen-fixing growth-promoting bacteria isolated from the rhizosphere play a crucial role in regulating soil nitrogen availability for plants. Among the nitrogen-fixing bacteria that inhabit the rhizosphere, Bacillus strains have garnered attention for their exceptional ability to fix nitrogen and promote plant growth. These beneficial microbes possess a suite of plant growth-promoting traits, making them valuable assets for sustainable agricultural practices.

This study focused on isolating nitrogen-fixing bacteria. Over 80% of the isolated nitrogen-fixing bacilli were obtained from the rhizoplane, likely due to the high concentration of root exudates and microbial accumulation in this region. Despite previous studies indicating higher bacterial diversity in the rhizosphere, our findings suggest a distinct microbial niche within the rhizoplane supporting nitrogen-fixing bacteria. To select Bacillus strains with the highest plant growth-promoting potential, we screened them based on their growth ability, resulting in the selection of five promising strains. Phosphorus, a critical nutrient for plant growth, is often limiting. Bacillus strain S3 demonstrated the highest phosphate dissolution capacity (278.3 µg/mL). Bacilli secrete organic acids and produce siderophores that chelate iron bound to mineralized phosphates, making them accessible to plants. Moreover, studies have shown that bacilli can convert insoluble inorganic and organic phosphorus compounds into soluble forms via ACC deaminase enzyme production. Most strains exhibited ACC deaminase activity, enabling them to utilize 1-aminocyclopropane-1 as a nitrogen source. Siderophores, known for their biocontrol potential against plant pathogens, were produced by all strains except S3. Indole-3-acetic acid, a key plant hormone that promotes plant growth and germination, was produced in significant amounts by Bacillus strain S3. IAA production varies among species depending on nutrient availability. Bacillus indirectly enhances root growth by producing ammonia, a nitrogen source. Bacillus strains S3 and S5 exhibited the highest ammonia production, corroborating previous studies. Additionally, all strains demonstrated over 70% growth inhibition against fungal strains. Collectively, the obtained results underscore the promising potential of the native Bacillus strains isolated in this study for biofertilizer development. Their diverse plant growth-promoting traits, including nitrogen fixation, phosphate solubilization, ACC deaminase activity, siderophore production, IAA synthesis, ammonia production, and antifungal activity, make them valuable candidates for sustainable agricultural practices.

Aflatoxin in pistachios and some other foods and feeeds causes diseases in human and animals. Aspergillus flavus has been reported as an important producer of aflatoxin. In this research, antagonistic bacterial agents were isolated from pistachio orchards in Yazd province, Iran, and their antagonistic properties were investigated on A. flavus isolates.

Different isolates of Bacillus sp. and Aspergillus sp. were isolated from different pistachio orchards in Yazd. A. flavus species were identified and various biochemical and molecular characteristics of bacterial isolates were investigated. Also, the antibiosis properties and production of antibiotics and effect of extracellular secretion, antifungal volatile substances and siderophore of the isolates were evaluated on A. flavus.

According to the results of biochemical and molecular tests, all isolates were identified as Bacillus. Strain Pr3 had the most effect with 95% and strains Pr5 and Pr7 had the least effect on A. flavus with 50%. The results of the antibiotic production test using chloroform method showed that isolates Pr3 and Pr7 had the highest and lowest antibiotic production with 84.35 and 38%, respectively. In this study, isolates Pr1, Pr2, Pr3 and Pr9 significantly produced extracellular     secretion, siderophore and antifungal volatile substances and showed different amounts of effect on A. flavus.

According to the results obtained from this research and the findings of other related researches, different Bacillus species and their metabolites have high antagonistic properties against A. flavus, which can be used as an effective and promising method to inhibit the growth of the fungus and to prevent the production of aflatoxin.

Plant growth-promoting rhizobacteria (PGPR) is an alternative to chemical pesticides against harmful microorganisms especially soil-borne diseases. Fusarium oxysporum is one of the important pathogenic fungi of tomato wilt that causes serious damage to agricultural products.

The purpose of this research is to investigate the inhibition of the growth of Fusarium oxysporum with bacteria isolated from soil in laboratory conditions.

In order to isolate biological inhibitors, isolates were screened based on the ability to auxin and phosphorus solubilization, siderophore production and fungal growth inhibition. Molecular identification of selected isolates was done by 16SrDNA gene amplification. Investigating the ability of bacteria to control the pathogen Fusarium oxysporum. It was done under greenhouse conditions.In this study, to screen successful bacterial isolates, the inhibition of pathogen growth was evaluated in-vitro.

Moreover,. Among the 80 isolates studied, seven isolates had the ability to produce auxin, ten isolates had the ability to P solubility, six isolates had the ability to produce siderophore, and seven isolates had the ability to inhibition pathogen growth. Among the isolates 56 and 83 had the highest amount of auxin production and the P solubility and the fungal growth inhibition. Multiple alignment of the 16SrDNA sequence of two selected bacteria with other 16SrDNA sequences in the NCBI gene bank showed that isolates 56 and 83 with 98 and 99.9 percent similarity belong to Bacillus amyloliquefaciens and Bacillus atrophaeus, respectively.

Among the isolates, seven isolates in vitro conditions showed a good ability to inhibit the growth of F. oxysporum. In greenhouse experiments, all 5 isolates as significantly (P<0.05) they controlled the disease, and the most control was related to isolate 56.

In this study, the effect of dietary butyrate monoglyceride and probiotic (Bacillus subtilis and Bacillus licheniformis) supplementation were evaluated on growth performance and the enzymatic antioxidant activity of Nile tilapia (Oreochromis niloticus). Fish were divided into 4 treatments with 3 replications including control, 10g/kg butyrate monoglyceride (AB1), 5g/kg probiotic Bacillus (AB2), 10g/kg butyrate monoglyceride and 5g/kg probiotic Bacillus (AB3). 144 fish with an average weight of 12±0.58g were fed for 8 weeks. This study showed that applying butyrate monoglyceride and probiotic Bacillus in the feeding of Nile tilapia significantly improved the growth indices of final weight gain (FWG), daily weight gain (DWG), protein efficiency ratio (PER), and FCR compared to control (P<0.05). All experimental diets had higher levels of catalase, glutathione peroxidase and superoxide dismutase activity compared to control (P<0.05). However, the highest levels of superoxide dismutase activity were measured in treatment AB3. The present study indicated that singular and combined dietary administration of butyrate monoglyceride and probiotic Bacillus had a significant impact on growth performance, and liver and serum enzymatic antioxidant activity of Nile tilapia.

Microbes that reside inside the plant tissues are known as endophytes. These microbes produce an array of compounds that have the potential to be used in modern medicine and agriculture. The aim of this study was to isolate, screen, and identify endophytic bacteria that have antimicrobial activity toward phytopathogenic bacteria. Aromatic plants such as Satureja khuzestanica are used in traditional medicine due to their secondary metabolites but information regarding their naturally occurring bacterial endophytes is limited.

In the present study, 27 strains of endophytes were isolated from S. khuzestanica. Based on the sequencing of the 16S rRNA gene, isolated bacterial strains with the highest activity against phytopathogenic bacteria belong to Bacillus, Streptomyces, and Pseudomonas genera. The bioactive secondary metabolites of these endophyte bacteria were extracted using ethyl acetate, followed by Gas Chromatography-Mass Spectrometry (GC-MS) analysis under standard conditions. The minimum inhibitory concentration (MIC) values were determined for five species of bacteria via the microbroth dilution technique. The crude extracts of the five selected bacterial endophytes indicated an antimicrobial activity against five phytopathogenic species.

Data analysis showed significant differences in antimicrobial activity that ranged from 0.312 mg/ml to 2. 5 mg/ml. The minimum bactericidal concentrations ranged from 0.625 mg/ml to 10 mg/ml.

The major compounds in GC-MS analysis of endophyte bacteria in this study were 2,4-di-tert-butylphenol, beta-d-glucopyranose, hexadecane, tetradecane,  eicosane, and dibutyl phthalate. This study reports for the first-time bacterial endophytes of S. khuzestanica, with antimicrobial activity against bacterial phypathogens. Our findings provide new insights into the antimicrobial activities of natural bacteria endophytes from S. khuzestanica.

The aim of this study was to isolate and identify a-amylase-producing bacteria present in mangrove ecosystems on Qeshm Island, Hormozgan, Iran. Samples of mangrove leaves and roots were screened for a-amylase activity using Lugol’s solution. Crude extracts were prepared of positive samples, and their a-amylase activity was determined by the Bernfeld method. The two strains with the highest activity were identified by molecular analysis of their 16S rRNA genes. a-Amylase production and activity were optimized by varying temperature and pH. 46 bacterial strains were isolated from mangrove tree leaf and root samples. Of these, 28 strains were capable of producing a-amylase. 16S rRNA gene sequence analysis of two strains with the highest enzyme production identified them as Bacillus sp. strain HR10 and Bacillus sp. strain HR11. The optimum temperature for enzyme production was 35 and 30 °C for strains HR10 and HR11, respectively, and the optimum pH was pH 8 for both strains. The highest enzyme activity was observed at 70 °C and 60 °C for the HR10 and HR11 strains, respectively, and the optimum pH was pH 8 for both strains. In conclusion, we have shown that bacteria isolated from mangrove leaf and root samples are potential source of a-amylases, tolerating a wide range of temperature and pH. Such a-amylases may be of interest for use in environmentally friendly industries.

Improper use of soil resources leads to reduced fertility and soil degradation, and ultimately reduced crop production. Chemical fertilizers are a very strong competitor to biofertilizers because they are cheaper, easier to access, and faster return on investment. Accordingly, the aim of this study was conducted to evaluate the rhizosphere bacteria that stimulate plant growth and provide biosecurity with the approach of modifying the root structure of plants. The study showed that the rhizosphere supports the development and activity of a large and diverse community of microbial organisms, including organisms in plant growth, which can be used in the biological control of plant diseases. Bacillus sp. and Pseudomonas sp. It also causes an increase in all biological diseases. These microorganisms are investigated in the present study. Findings showed that reducing production costs on a large scale is a difficult task but can be achieved with careful research. In addition, the analysis of the benefits, risks, and limitations of the use of Rhizobacteria requires a more comprehensive and detailed investigation. Because the choice of appropriate method of plant disease control is based on balance.

Enzymes are selective proteins that catalyze all metabolic reactions found in living organisms. Millions of enzymes are produced by prokaryotes and eukaryotes. Marine sponges have developed a enormous quantity of diverse microorganisms such as bacteria, fungi, viruses, protozoa, and single-celled algae and the nature of the sponge-microbe interaction is diverse. Marine sponge's symbiotic bacteria can comprise as much as 40% of sponge tissue volume. At least 32 bacterial phyla and candidate phyla were described from marine sponges by both cultivation-dependent and cultivation-independent techniques. Symbiotic microorganisms in sponges can be sources of various natural products, because metabolites previously ascribed to sponges have recently been demonstrated to be biosynthesized by symbionts. If symbiotic microorganisms from which some natural products are derived can be cultured, the microorganism could be used in a mass production of the bioactive comopounds. The goal of this research is isolation of Amylolytic bacteria from marine sponges and optimization of bacterial growth and amylase production in most amylolytic isolate. Symbiot bacteria were isolated using serial dilution method and differential analyses done for isolated bacteria. Most effective isolate was selected by using qualitative starch hydrolysis method.

Morphological and biochemical characteristics were studied using Bergey’s manual of systematic bacteriology. Differential analyses were performed by catalase and Gram test TSI, H2S, VP, MR tests. Preliminary screening and quantification of amylase activities were analysed in selected isolates by starch agar plate and dinitrosalicylic acid (DNS) method respectively. In order to optimize the enzyme production, the fermentation process was carried out under M9 medium using various sodium chloride concentrations (2–14%). To evaluate the effect of pH on the production of Amylase, the best amylase producer isolate was cultured at M9 medium with different pH rang 4-8. After incubation time it was subjected to amylase activity assay. Isolate SS1 was grown in M1 medium at 28°C for 7 days. DNA extraction was done using Cinnapure DNA Kit for isolation of DNA from gram positive bacteria. PCR amplification of 16S rRNA gene was performed, the specific actinomycete primers, F27 and R1492 were used to amplify 16S rDNA. The resultant 16S rRNA gene sequences were aligned manually with corresponding almost complete sequences. The 16S rRNA gene sequence search was performed using the BLAST program available from the National Centre for Biotechnology Information (NCBI) and the isolate was identified to generic level Using the CLUSTAL-X Multiple Sequence Alignment Program (Strasburg, France), The Phylogenetic tree was constructed by Neighbor-Joining method using MEGA 6.06. The reliability of the phylogenetic tree was tested by bootstrap analysis using 1,000 replicates.

Biochemical analyses showed that all tests were catalase and Gram positive none of them produced H2S and TSI, MR, VP tests were negative. According to 16S rRNA sequences result the most effective isolate was belong to Bacillus genus and Optimum growth condition was found at 12% NaCl concentration, 35˚C temperature and pH 12. Maximum amylase activity in optimum condition was 109 Unit (one Unit is amount of enzyme that release one microgram of glucose in a minute).

The results showed that enzyme production is related to growth of bacteria conditions and the amylase gene should amplify from selected isolate and clone in suitable host for more studies.

Salinity stress is an important challenge for wheat production in the world. Plant growth promoting rhizosphere bacteria, isolated from halophytic plants, can increase the tolerance of crop plants to salinity by direct and indirect mechanisms. In this study, plant growth-promoting traits of bacterial strains (Bacillus safensis, Bacillus pumilus and Zhihengliuella halotolerans), isolated from the rhizosphere of several halophyte plants, were deterimined and their effects on some vegetative traits and ionic content of wheat plant irrigated with saline water ( 0.2, as control,  4, 8 and 16 dS/m) were measured. Result showed that all three bacteria were able to produce auxin, hydrogen cyanide, siderophore, 1-aminocyclopropane-1-carboxylic acid deaminase and soluble phosphate. The increase in salinity levels caused increase in the concentration of sodium and decrease in the concentration of potassium, calcium and phosphorus in wheat leaves, as well as decrease in stem length, shoot and root dry weight, root to shoot dry weight ratio and total biomass. In wheat plants irrigated with saline water and inoculated with the bacterial strains, sodium concentration decreased up to 17.7% and concentrations of potassium, calcium, phosphorus and potassium to sodium ratio increased up to 33, 25.7, 200.4 and 41%, respectively. The most efficient bacterium was found to be Z. halotolerans. All bacterial isolates also increased stem length, shoot and root dry weight, root to shoot dry weight ratio and total biomass by 17, 58.6, 137, 88 and 66 %, respectively. The results of this study showed that the plant growth-promoting bacteria of rangeland halophytic plants potentionally improve the growth indices of wheat plants in saline conditions. These results also showed that the rhizosphere of halophytic plants in rangelands can be a good source for the isolation of salinity-resistant bacteria to improve the resistance of wheat plants to salinity.

Millions of tons of plastics are produced annually in the world, which are very durable and take hundreds of years to decompose on their own. Bioplastics are a special type of plastic that is produced from sources of vegetable oils, starches, cellulose or bacterial derivatives and is very different from ordinary plastics in this regard, which will be a good alternative to plastics in the future. 70 samples were collected from waste recycling site, cultured and purified on nutrient agar and these samples were stained with blue indigo staining method to detect polyhydroxy butyrate (PHB) generating isolates And cultured for 2 days at 37 ° C in Minimal Broth Davis medium.After placing the samples on the slide and staining according to the intensity of the color that was created, it was used to produce bioplastics. The results of this study showed that the microorganism Bacillus cereus produces abundant poly-3-hydroxybutyrate in both environments (wastewater and soil), which is used to produce bioplastics on both laboratory and industrial scales. According to the results, the production of bioplastics is possible through bacilli isolated from bacterial isolates.

In this study, the role of probiotic and halophilic bacteria were studied in biofloc system using different carbon sources including corn starch (treatments 1 and 4), beetroot molasses (treatments 2 and 5), rice-bran (treatments 3 and 6), with sugar cane vinasses (used in all treatments) at presence of commercial probiotics (Bacillus subtilis and Bacillus coagulans) (treatments 1, 2 and 3) and combination of probiotics and halophylic bacteria (treatments 4, 5 and 6) at salinity of 60±5g/L during 42 days. Minimum concentrations of nitrite and nitrate were recorded in treatment 6 and lowest ammonia in treatment 1. The highest floc volume were produced in treatments 2 and 5 (41-48mL/L). In terms of nutritional value, significantly higher protein (20-25%) and ash (75-80%) were detected in treatments 2, 3, 5 and 6. But significantly higher carbohydrate (64%) was detected in treatments 1 and 4. Fatty acid analysis of the bioflocs showed that treatments 2 and 5 had highest PUFA n-3 (32%) and treatments 3 and 6 had significantly higher MUFA (22-25%). Results of this research showed that different carbon sources had significant effect on biofloc quality, but the use of probiotics separately or in combination with halophilic bacteria had no significant effect on biofloc quality.

Folic acid or vitamin B9 is one of the most essential vitamins, which plays a key role in the transport of carbon and many biochemical pathways and its deficiency can lead to neurological diseases, anemia and developmental problems in children. The present study aimed to take a step towards producing this vitamin from native strains by isolating and sequencing the folic acid production gene from soil isolated bacillus and cloning it in Escherichia coli.

In this study, 40 samples were collected from 5-10 cm depth from different areas around Sirjan city. Bacillus bacteria were isolated by molecular and biochemical methods. By PCR method, bacteria with FOLA gene were identified and the amplified gene was cloned into E. coli and sequenced. Gene expression was then evaluated by Real time PCR and its phylogenetic relationships were determined.

As a result of screening of 40 soil samples sent to the laboratory, a total of 12 suspected colonies were isolated from Gram-positive bacilli which were identified based on morphological, microscopic and biochemical characteristics and all species were identified as having FOLA gene. FOLA cloning was performed successfully and confirmed its gene expression.

In the present study, the FOLA gene from Bacillus Halotolerance isolated from the soils of the surrounding areas of Sirjan was successfully cloned into PTG19-T expression vector and its successful expression showed that it could be expanded by this method for industrial production of Folate.

Nattokinase is an enzyme extracted from Japanese food produced in the fermentation process. This enzyme has significant positive effects in the treatment of cardiovascular diseases, the treatment or prevention of amyloid diseases such as Alzheimer disease and the reduction of blood cholesterol. This genomic study aimed to investigate the Nattokinase isolated from soil bacilli in areas around Tehran and its cloning in Escherichia coli bacteria for medicinal use.

In this study, 60 samples were collected from 5-10 cm depth of soil of different areas around Tehran and their Bacillus bacteria were isolated by molecular and biochemical methods. By the PCR method, the bacteria with the Nattokinase gene were identified and the amplified gene was cloned into E. coli and sequenced. The gene expression was then evaluated by Real Time PCR and its phylogenetic relationships were determined.

As a result of screening soil samples sent to the laboratory, a total of 12 suspected colonies were isolated from Gram-positive bacilli which were identified based on morphological, microscopic, and biochemical tests. Then, 11 species was determined as target genes. The cloning and expression of Nattokinase gene were successfully performed and the homology of 99-100% with other enzymes was observed.

In the present study, the Nattokinase gene from Bacillus subtilis RH5 isolated from soils around Tehran was successfully cloned into PTG19-T expression vector. The successful expression of its gene showed that it could be expanded by this method for industrial production.