جستجوی مقالات مرتبط با کلیدواژه « bacillus licheniformis » در نشریات گروه « پزشکی »

 Antibiotic resistance is the ability of microbes to survive antibiotic exposure with standard doses. Regular updating of antibiotics is one solution to overcome antibiotic resistance. One source with potential new antibiotics is moonmilk from caves because it contains various bacteria proven to have antibacterial activity. The objective of the present study is to explore the potential of moonmilk microbes from Pindul cave, Indonesia, as a source of new antibiotic compounds.

 The antibiotic potency test was divided into six groups with various concentrations of isolated moonmilk bacteria (IMM) supernatant 25%, 50%, 75%, 100%, negative control (-), and positive control (+). All groups were further tested for antibiotic susceptibility using the disk diffusion (Kirby and Bauer) method to pathogenic resistant bacteria Escherichia coli ATCC 25922 and Staphylococcus aureus ATCC 25923 on Mueller Hinton agar medium. PCR and Sanger sequencing method using 16S rRNA primers was performed to identify species of isolated moonmilk bacteria.

 The 16S rRNA sequence analysis showed that the IMM shared a 99,64% (1399 nucleotide match) similarity with Bacillus licheniformis strain IND706. The results showed that moonmilk bacteria had antibacterial activity against E. coli ATCC 25922 and S. aureus ATCC 25923. The highest inhibition zone was observed for the bacterial extract concentration of 75% (42 mm) in E. coli ATCC 25922 and 100% (23 mm) in S. aureus ATCC 25923 medium.

 IMM supernatant extract from Pindul cave, Indonesia, has the potential to control antibiotic-resistant bacterial pathogens.

 The present study aimed to evaluate the optimum conditions for extracting and purifying penicillinase enzyme. The enzyme source was Bacillus licheniformis 6346 obtained from the Iranian Research Organization for Science and Technology.

 B. licheniformis was cultured in a medium containing mineral salts, nitrogen compounds, and cultured carbon sources. Following the harvesting and preparation of bacterial suspension, the destruction of the bacterial cell wall and crude cell extraction was completed using a combination of lysozyme and weak ultrasonication. Afterward, enzyme amount was determined utilizing chromatography and electrophoresis. Furthermore, the optimum growth temperature and incubation time were assessed based on the absorbance of samples at 240 nm, enzyme activity, aerification intensity optimization, enzyme production time, and optimum pH.

 Approximately 8 g of cells were retrieved in one liter of culture. The optimum pH was determined as 6.8. The heat stability evaluation of the enzyme at different times revealed that the enzyme was stable for more than 1 h at 20°C-45°C, while it is inactivated in 10 min at 60°C. Moreover, the best incubation time for this bacterium was obtained as 9 h at 30°C. In terms of aerification intensity, the highest enzyme production rate of 2394 U/mL was achieved in a 250 mL Erlenmeyer flask with a 50 mL culture medium at 200 RPM. More aerification led to the inhibitory effect of oxygen and reduced enzyme activity.

 Our findings showed that the bacterium B. licheniformis 6346 can be used for producing penicillinase enzyme in optimum conditions.

Increased usage and improper management of electronic wastes result in immense environmental pollution. Although conventional techniques are well known for heavy metals removal from the environment, their high cost and severe environmental consequences indicate the urgent requirement of cost-effective methods of heavy metals uptake. Bioaccumulation can be considered as an alternative to the traditional methods in terms of their cost-effectiveness and maximum recovery of the metal ions. This study deals with the isolation of heavy metals tolerant Gram-positive bacterial strain, Bacillus licheniformis JAJ3, and its application in bioaccumulation of copper, lead, and nickel and bioleaching of heavy metals from electronic waste. 16S rRNA sequencing was performed to identify the bacterial strain. The accumulation study was carried out in a liquid medium and analyzed using atomic absorption spectroscopy. Bioleaching activity was checked using the one-step procedure. For bioleaching studies of heavy metals, printed circuit boards (PCBs) were used as a source of electronic wastes. Scanning electron microscopy and energy dispersive spectroscopy were used to record the changes before and after experimental procedures. The organism was able to accumulate 98.6% copper, 64.6% lead, and 57.3% nickel. The bioaccumulation reaction followed pseudo-second order kinetics model (R2 value 0.92, 0.92, 0.99 for copper, lead, and nickel bioaccumulation respectively). Efficient bioleaching activity was shown by the strain. The experimental analyses confirmed that the strain is efficient in the bioleaching of heavy metals from electronic wastes and thus can be used in management of the electronic wastes.

Bacillus licheniformis is a potential cause of spoilage in pasteurized products. The aim of this study was to identify and isolate B. licheniformis from commercial pasteurized fruit juices distributed in the West Azarbaijan Province, Iran. Sixteen fruit juice samples including four apple juice and 12 orange juice samples were collected from five fruit juice manufacturing companies in Iran. The samples were tested for the presence of B. licheniformis by culture in specific media and biochemical testing. Suspected samples were also investigated for the presence of the bacterium by polymerase chain reaction using specific primer for the gyrB gene. Three samples (18.75%) from the 16 tested fruit juice samples were found as positive. In other words, one apple juice sample (25%) and two orange juice samples (16.66%) were contaminated with B. licheniformis. Isolation of this bacterium indicates the unsuitable manufacturing conditions and ineffective bacterial decontamination, which might also be favorable for the growth of other fruit juice spoilage bacteria

Proteases are often used as catalysts for peptide synthesis. To shift the thermodynamic equilibrium in favor of the peptide synthesis, reaction media should contain organic solvent. However, known enzymes are usually inactivated by adding organic solvents to reaction media. In this study, we reported a bacterium isolated from soil of Ahvaz, Iran contaminated by crude oil producing an organic solventstable protease, and the effect of organic solvents on proteolytic activity was investigated. Isolated bacterium was cultured in mineral salt medium containing glucose and peptone. After 48 hours incubation at 35 °C and 130 rpm, culture media were centrifuged and resulted supernatant filtered using 0.22 μm nitrocellulose membrane filter. Proteolytic activity of supernatant was determined by Keay and Wildi method (1970) by using casein as substrate. The effects of different concentrations of various organic solvents including acetone, ethanol, pentanol, cyclohexane, benzene, n-hexane, and n-decane and, also, the effects of temperature and pH on protease stability and activity were examined. According to 16SrDNA sequencing, strain ISA9 was identified as a new strain of Bacillus licheniformis. This strain was able to produce an extracellular organic solvent- tolerant protease. After 30 minutes incubation at 37 °C, caseinolytic activity of crude protease was increased in 25 and 50% of acetone, ethanol, benzene, cyclohexane, and hexane compared to non-solvent control. The enzyme was also activated 1.64, 1.23, and 1.17 times by 75% (v/v) of benzene, decane, and hexane, respectively. The protease was active in a broad range of pH (from 6 to 10) with the optimum pH 10. The optimum temperature for the activity of this protease was 70 °C and the enzyme remained active after incubation at 30-50 °C for 30 minutes. In this study, we isolated B. licheniformis producing an organic solvent-stable protease from oil-contaminated soil. The protease was stable and active in various organic solvents. By purification, the protease could be used as a biocatalyst for organic solvent-based enzymatic synthesis.